Do you always feel confident when selecting heat treating equipment? ¿Se siente siempre seguro cuando selecciona equipos de tratamiento térmico?
There are many factors involved when making a purchase. Often, key considerations may be missed. Read this guide on how to select and buy new equipment by Carlos Carrasco, founder of Carrasco Hornos Industriales.
This original content article was originally published inHeat TreatToday’s November 2021 Vacuum Furnaceprint edition in English and Spanish.
Carlos Carrasco Founder Carrasco Hornos Industriales
Why Is This Guide Helpful?
There are many reasons to select industrial furnaces carefully. One is the cost of the furnace. Another is realizing heat treating will affect the product and the bottom line. There is more specialized engineering in heat treating equipment than is apparent from the outside.
The purpose of this guide is to help engineers make the best equipment selection. The decision will affect not only the project, its budget, and results, but will also reflect the buyer’s knowledge. After the heat treating equipment is selected, the realization may occur that perhaps insufficient thought was given to potential maintenance problems or the work required to keep it in top working condition.
The following steps, gathered from more than 50 years of experience in the fields of manufacturing, sales, and maintenance, will be a useful guide to selecting heat treating equipment that will please both management and operators.
Vacuum high-pressure hardening furnace
Step One: Quote Request
When requesting a quote, management knows the exact requirements the heat treated products must have. A reliable supplier should be able to understand all requirements for a quote. Requests must be clear, concise, and contain at least the following information:
Heat treating processes that will be carried out on the equipment
Shape, general dimensions, and weights of the product(s) to be heat treated
Production volumes per hour, day, or month
Number of hours available for heat treating
Part material
Fuel type, or if the heating will be done with electricity
Voltage available in the plant
Space available for installation of equipment
Special considerations for handling loading and unloading
Furnace manufacturers need the above information to begin to create a series of options for the equipment that will be most suitable for the required processes. For example, hourly production defines: the dimensions of the space to heat the load, the type of furnace (continuous or batch), the amount of heat to be released in the furnace, the loading and unloading method, and the devices for accommodating or transporting the load such as trays, baskets, or conveyor belts. All these considerations influence both the initial cost and the operating cost, because in the end, the cost of the proposed equipment and its functionality are directly related to the specifications of the request for a quote.
It is difficult to attempt to use one furnace for all heat treating processes or to attempt to take into account future production needs that may not be necessary. It is impractical to carry out several processes that require different temperatures or have different production volumes. Trying to do so leads to oversized and over-budget equipment.
Vacuum low-pressure carburizing furnace
Step Two: Supplier Selection
Quote requests should only be submitted to manufacturers with the technical capacity and experience to prepare an offer that satisfies the request. Always use references from previous installations with similar quote requirements.
Considering the potential for financial gain, the cost of heat treating equipment can be appealing. The design and construction of heat treating equipment involves a considerable amount of engineering resulting from expensive investments in research and development. This research and development is influenced by user feedback detailing equipment failure. This feedback creates opportunities for manufacturers to fix equipment issues. Without the added benefit of other heat treater’s feedback, equipment failure is more likely. Finding a manufacturer with experience is crucial.
Only suppliers with experience and solid technical capacity will be able to guarantee results from the start. The goal is to receive equipment that requires no corrections after the first load leaves the furnace and to not have to rework the design.
Step Three: Study and Evaluation of Offers
A failed project is too much to risk, and so the responsible supplier will invest time and money in the study and preparation of the offer.
Every responsible supplier has been disappointed by an offer read backwards — when the potential customer reads the price first. Is the overriding need to stay within a certain budget or for heat treating equipment that is capable of processing parts to meet specifications? A careful reading of the offer may justify the cost of the furnace in relation to production needs. If there is a confusing section of the offer, it is important to clarify with the supplier. Investment in production equipment is very important, but it is even more important that the investment be profitable.
The heat treating equipment must satisfy a production need and certain metallographic specifications. Consequently, the dimensions of the space where the parts will be placed may be the main factor in the design of the furnace. This is because metals are only capable of heating up to a certain temperature at a rate that is determined by the heating method, geometry, and load arrangement. Only experienced vendors can make the correct calculations to meet the production needs of the project. Be sure to understand the calculations that lead to the sizing of the proposed system.
How are the parts supported and/or transported within the furnace? This is a point of great importance for the initial cost of these components and for the costs of future maintenance. Keep in mind that any mechanism that works at high temperatures will always be problematic for maintenance and replacement. Cast link belts, for example, have a higher initial cost, but they withstand heavy loads longer than metal mesh belts. However, there is a notable difference in the cost of components made of chromium-nickel alloy and those of carbon steel. Since chromium-nickel materials are able to withstand higher temperatures, their use is recommended and almost essential.
Furnaces tend to deteriorate rapidly where the heat is being lost. Make sure the door design is the best possible to avoid heat loss. Be sure that all doors included in the design are necessary. Doing so will save maintenance costs.
When it comes to quenching, oil or water circulation systems are extremely important, as is tank capacity. Otherwise, the quenching medium may overheat, causing unsatisfactory results.
In an oven intended for low temperature operations 356°F–1,112°F (180°C–600°C), for example tempering processes, it is necessary to have a fan to recirculate the hot air from the furnace. The uniformity of the temperature in the parts and the speed at which they heat up depends on the speed of recirculation, the weight of the air, and the design of the furnace, which must force the passage of air optimally through the load with the use of deflectors, screens, or distribution plenums. In high temperature furnaces, 1,292°F–2,192°F (700°C–1200°C), the heat transfer depends on the radiation toward the load and its exposed surface, so a recirculation fan is not necessary. Heat treatment is a critical process and temperature pyrometers must have the necessary precision.
List any doubts about the offer and ask the supplier to clarify at length in writing. The answers will make it easier to do a second analysis of the offer and compare it with other offers. In addition, the written clarifications will be a record for review by other collaborators on the project. Ask for feedback and observations on the proposals to get a second opinion.
Ask suppliers to provide a list of similar installations. Industry colleagues are generally unbiased in their comments about their experience with a particular supplier.
Finally, make a comparison chart in the most objective way possible. Keep in mind the fact that offers often do not include some subjective issues that may be important for a final selection. For example, some vendors are likely to have greater knowledge and experience in certain processes, simply because they have invested time and money to fi nd the best solutions to the process and those experiences could be beneficial.
Step Four: The Price
Understanding the scope of the received proposals that meet production and quality requirements is not all that goes into selecting heat treating equipment. After all this, there are still significant differences between various suppliers. Price is one of these differences. At this stage, the industrial furnace manufacturer will need to justify costs. It will be easy to tell if the manufacturer is thinking of the buyer as a future satisfied customer, or only of the economic benefits the sale will bring.
Conclusion
There are innumerable cases in which the equipment was poorly selected: “The substation and/or the cooling tower did not have the capacity;” or “The equipment is not what we expected;” or “They never told us that the furnace needed gas in those capabilities.” These are just a few of the possible comments everyone has heard.
Selecting heat treating equipment should be done slowly, analyzing all the options, weighing the differences between providers, and seeking clarification. Ask the supplier for multiple equipment options like requesting spare parts for the first year of operation.
Ultimately, time will tell if the furnace selected was the right choice. These recommendations provide a guide to making that decision. We sincerely hope that these recommendations will guide you in the selection of industrial furnaces for heat treating.
About the Author:
In addition to being the founder of Carrasco Hornos Industriales — furnace experts, consultants, and independent sales representatives for various furnace companies and spare parts — Carlos Carrasco is the founder and former president of ASM International, Mexico Chapter with more than 50 years of experience in the heat treat industry.
¿Se siente siempre seguro cuando selecciona equipos de tratamiento térmico? Do you always feel confident when selecting heat treating equipment?
There are many factors involved when making a purchase. Read this guide on how to select and buy new equipment by Carlos Carrasco, founder of Carrasco Hornos Industriales. The Spanish version is below, or you can check out both the Spanish and the English translation of the article where it was originally published: Heat Treat Today'sNovember 2021 Vacuum Furnaceprint edition.
¿Se siente siempre seguro cuando selecciona equipos de tratamiento térmico? Hay muchos factores involucrados cuando se hace una compra. Consulte este artículo para conocer los pautas que lo ayudarán en el proceso de selección y compra. Autor: Carlos Carrasco, fundador de Carrasco Hornos Industriales.
Carlos Carrasco Fundador Carrasco Hornos Industriales
¿Por qué es conveniente esta guía?
Este artículo ayuda a los ingenieros a comprar equipos de tratamiento térmico. Hay muchas razones para seleccionar cuidadosamente los hornos industriales. Uno, es el costo del horno en sí y otro, es que el producto que se está tratando térmicamente afectará los resultados de su empresa.
En un equipo para tratamiento térmico, hay más ingeniería especializada de lo que parece en el exterior. Hay varias y muy sólidas razones, para hacer una cuidadosa selección de estos equipos, pues sus componentes son inherentemente de alto precio y en la mayoría de los casos, los resultados del tratamiento térmico tienen un importante efecto en la economía de su empresa.
El objetivo de esta guía es el de tratar de ayudarle a hacer la mejor selección del equipo; porque su decisión afectará no sólo al proyecto, su presupuesto y resultados, sino también a su capacidad como ejecutivo. No será la primera vez que escuche usted comentarios respecto a equipos adquiridos por la empresa en etapas anteriores a la suya o en la misma, y es común en la industria, tanto nacional como internacional, que los operadores o el personal de mantenimiento, comenten: “Cuando adquirieron este horno, nadie pensó en los problemas de mantenimiento [. . .] Como ellos no son los que lo usan día con día, no se dieron cuenta de cuánto trabajo se requiere para mantenerlo o bien para trabajar confi ablemente con él”.
Déjese ayudar, pues como ingenieros consultores en hornos y experiencia de más de 50 años en este ramo; tanto en la fabricación, venta y mantenimiento, con buenos resultados, los comentarios siguientes seguramente pensamos le serán útiles.
Horno de temple al vacío
Primer paso: solicitud de la cotizacion
Al solicitar una cotización, nadie mejor que Ud. puede conocer los requisitos que deben tener sus productos tratados térmicamente. Un proveedor confiable, debe ser capaz de entender todas sus necesidades de tratamiento térmico a partir de la solicitud de cotización que le presente. Consecuentemente, su solicitud deberá ser clara, concisa y tendrá como mínimo los siguientes datos:
Proceso de tratamiento térmico a efectuarse en el equipo.
Forma, dimensiones generales y pesos del (los) producto(s) a tratar térmicamente.
Volúmenes de producción por hora, día o mes.
Número de horas disponibles para el trabajo de tratamiento térmico.
Material del que están construidas las partes.
Combustible disponible o en su caso, si la calefacción será por medio de electricidad.
Tensión eléctrica disponible en la planta.
Espacio disponible para la instalación del equipo.
Consideraciones especiales del manejo de la carga y la descarga.
Es conveniente que Ud. sepa que los fabricantes de hornos necesitan la información anterior para empezar a definir una serie de opciones del equipo que podría ser el más adecuado para sus procesos. Por ejemplo, la producción horaria define: Las dimensiones del espacio para calentar la carga, el tipo de horno, continuo o por lotes, la cantidad de calor a ser liberada en el horno, así como el método de carga y descarga y los dispositivos para acomodar o transportar la carga como charolas, canastillas o bandas transportadoras. Todo lo anterior influye, tanto en el costo inicial como en el de operación, porqué, a fin de cuentas, el costo del equipo propuesto y su funcionalidad, están en relación directa a las especificaciones de su solicitud de cotización.
Ah, y por favor, no trate de llevar a cabo todos los procesos de tratamiento térmico habidos y por haber en un único horno, ni tampoco quiera tomar precauciones de futuras necesidades de producción, de las cuales no tiene ahora ninguna certeza, ya que es difícil llevar a cabo en un solo horno varios procesos que involucran diferentes temperaturas, volúmenes de producción, etc. Un enfoque en este sentido conduce a equipos sobredimensionados y posiblemente fuera de su presupuesto.
Horno de vacío para carburizado a baja presión
Segundo paso: selección de proveedores
Presente su solicitud de cotización, solamente a quien tenga la capacidad técnica y experiencia para preparar una oferta, que satisfaga dicha solicitud. Utilice siempre referencias de instalaciones previas, y de preferencia similares, o mejor aún, iguales a la que usted requiere.
El costo de los equipos para tratamiento térmico es elevado y representa un atractivo a empresas e individuos que consideran la posibilidad de obtener beneficios económicos. La verdad, es que el diseño y construcción de estos equipos involucra una considerable cantidad de ingeniería, resultado de costosas inversiones en investigación y desarrollo con retroalimentación de casos prácticos (los fracasos enseñan) que han sido aprovechados en beneficio de los clientes potenciales. En suma, no permita que sus necesidades sean el método de aprendizaje de un proveedor. Aquí es donde no hay sustituto a la experiencia.
De hecho, el proveedor con experiencia y sólida capacidad técnica es el único que estará en posibilidad de garantizar resultados desde el principio. Desde luego, a Ud. le interesa obtener resultados dentro de especificaciones, desde la primera carga que sale del horno, y no comprar excusas, promesas y retrabajos para corregir lo que de inicio está mal hecho. Quizá, con buenas intenciones, pero poca y en algunos casos, nula experiencia.
Tercer paso: estudio y evaluación de las ofertas
El proveedor responsable invertirá tiempo y dinero en el estudio y preparación de la oferta, porque no puede correr el riesgo de que su proyecto no cumpla su cometido. Ahora la responsabilidad de evaluar las propuestas recae sólo en Ud.
No hay proveedor responsable, que no haya sufrido la decepción de que su oferta sea leída de atrás para adelante. Nos referimos a que el precio es la primera línea que lee el cliente potencial. Hágase una pregunta: ¿Su necesidad primordial es, un precio o un equipo de tratamiento térmico que sea capaz de procesar las piezas para que cumplan sus especificaciones de su tratamiento térmico? La lectura cuidadosa de la oferta, le dará la respuesta a sus necesidades de producción y a la justificación del costo del horno. Si hubiese alguna sección que no sea de su completa comprensión, no dude en llamar al proveedor para que haga las aclaraciones correspondientes. Por favor, no malentienda. La inversión en equipos de producción es muy importante, pero más importante será que la inversión sea rentable.
El equipo para tratamiento térmico debe satisfacer una necesidad de producción y de ciertas especificaciones metalográficas. Consecuentemente, las dimensiones del espacio en donde serán colocadas las partes, quizá sea el factor principal en el diseño del horno. Esto se debe, a que los metales sólo son capaces de calentarse hasta una cierta temperatura, a una razón que está determinada por el método de calefacción, la geometría y acomodo de la carga. Sólo los proveedores experimentados, pueden hacer los cálculos correctos para que su propuesta satisfaga las necesidades de producción del proyecto, del que Ud. es responsable. Solicite al proveedor le muestre y explique la memoria de cálculo que conduce al dimensionamiento del sistema propuesto.
¿Cómo se soportan y/o transportan las partes dentro del horno? Éste es un punto de gran importancia, por el costo inicial de estos componentes y también por los costos del mantenimiento futuro. Conviene tener en cuenta que, cualquier mecanismo que trabaje a alta temperatura, siempre será problemático su mantenimiento y reposición. Las bandas de eslabones fundidos, por ejemplo, (de mayor costo inicial) soportan mejor y durante mayor tiempo, cargas pesadas en comparación con las bandas de malla metálica. Sin embargo, hay notable diferencia en los costos de componentes de aleación Cromo-Níquel, comparados con los de acero al carbón, pero su uso es prácticamente imperativo.
Los hornos tienden a deteriorarse rápidamente en cualquier lugar en donde haya fuga del calor. Asegúrese de que el diseño de las puertas sea el mejor posible para evitar esta fuga de calor y también de que su horno no tenga puertas que no necesita. Esto le ahorrará costos de mantenimiento.
Por lo que respecta al temple, los sistemas de circulación de agua o aceite son de extrema importancia, lo mismo que la capacidad del tanque. De lo contrario, el medio de temple puede sobrecalentarse y los resultados de su proceso, podrían no ser satisfactorios.
En un horno destinado a operaciones de baja temperatura (180 a 600° C), por ejemplo, procesos de revenido, es necesario disponer de un ventilador para la recirculación del aire caliente del horno. La uniformidad de la temperatura en las partes y la rapidez a la que se calientan las mismas, depende de la velocidad de la recirculación, del peso del aire y del diseño del horno que debe forzar el paso del aire en forma óptima, a través de la carga, con la utilización de mamparas deflectoras o plenos de distribución. En los hornos de alta temperatura (700 a 1200° C), la transferencia de calor depende de la radiación de éste hacia la carga y su superficie expuesta, por lo que un ventilador de recirculación no es necesario. El tratamiento térmico, es un proceso crítico en lo que se refiere a temperatura. Los pirómetros reguladores de temperatura deben tener la precisión necesaria.
Escriba sus dudas sobre la oferta y pida al proveedor que las aclare en forma extensa y por escrito. Las respuestas le facilitarán el hacer un segundo análisis de la oferta y compararla con otras ofertas; además, tendrá un registro para revisión por parte de otros colaboradores en el proyecto. Pida opinión sobre sus observaciones a las propuestas, pues uno tiende a pensar en círculos.
Solicite a los proveedores, le entreguen una lista de instalaciones similares a la suya en las que hayan intervenido. Generalmente, los colegas industriales se muestran imparciales en sus comentarios sobre la experiencia que hayan tenido con un determinado proveedor.
Finalmente, haga un cuadro comparativo, en la forma más objetiva posible. No pierda de vista que, frecuentemente las ofertas no incluyen algunas cuestiones subjetivas, que pueden ser importantes para una selección final. Por ejemplo, es probable que algunos proveedores tengan mayores conocimientos y experiencia en ciertos procesos, sencillamente porque han invertido tiempo y dinero para encontrar las mejores soluciones al proceso y Ud. podría verse beneficiado con esas experiencias.
Cuarto paso: el precio
Seguramente, ahora que ha comprendido el alcance de las propuestas que ha recibido y que cumplen con sus necesidades de producción y calidad, se dará cuenta que aún así habrá diferencias entre sus distintos proveedores que podrían llegar a ser significativas.
Este es el momento en que un fabricante de hornos industriales podrá justificar sus costos. Y usted sabrá si ha realizado su oferta pensando en Ud. como un futuro cliente satisfecho o únicamente en los beneficios económicos que la venta le reportará.
Conclusiones
Son innumerables los casos en que los equipos fueron mal seleccionados: “La sub-estación y/o la torre de enfriamiento no tuvieron capacidad”, “El equipo no es lo que esperábamos”, “Nunca nos dijeron que el horno necesitaba gas en esas capacidades”. Estos son sólo algunos de los comentarios que todos hemos escuchado.
Tómese todo el tiempo que requiera para analizar sus opciones, piense el porqué hay diferencias de un proveedor a otro y solicite que le sean aclaradas. Pida a sus proveedores las opciones a las que puede acceder con el equipo que está solicitando y que éstas sean cotizadas como eso: opciones. No se olvide de solicitar las refacciones que pudieran ser utilizadas durante el primer año de operación de su horno.
Para finalizar, sólo el tiempo dirá si al seleccionar sus hornos, éstos funcionaron como se esperaba.
Sinceramente, esperamos que estas recomendaciones le orienten en la selección de hornos industriales para tratamiento térmico y estamos seguros, que así será. Seguro que debe haber más preguntas relacionadas con este tema, no dude en contactarnos para obtener ayuda.
Sobre el autor:
Expertos en hornos. Representantes de diversas compañías fabricantes de hornos industriales, partes de refacción y equipo de combustión. Con más de 55 años de experiencia en la industria y consultores. Carlos Carrasco es fundador y expresidente del capítulo México de la ASM International.
For Ovako, a centuries old manufacturer of engineering steel, innovative approaches to producing their product has taken the form of electrifying their roller hearth furnaces over the course of the past decade.
The process of converting to electric heating began in 2014, each furnace installed with up to 86 Tubothal® metallic heating elements from Kanthal. Now, 14 roller hearth furnaces are electrified. The estimated CO2 savings is around 1,400 to 2,000 tons per year per furnace.
“[In] our heat treatment shop in Hofors,” shares Anders Lugnet, a furnace technology specialist at Ovako (pictured above), “we originally had around 450 gas burners, and there was always a problem somewhere in one of them. Since replacing them with 300-odd Tubothal® elements, the daily maintenance is simply not there. Occasionally, an element needs to be replaced, but it is nothing compared to the way it was.”
He continues that, previously, NOx and CO2 emissions were problematic. But with green electricity, emissions are zero, and with no flue-gas losses, total efficiency has improved significantly.
Safety shutoff valves are the last line of defense against a potentially catastrophic incident. When conditions require, they interrupt the flow of fuel to the burner(s) and oven. There are many options when selecting fuel safety shutoff valves for your application. The construction and application of these devices is highly regulated by interlocking standards created by many different organizations. The goal of this article is to clarify how to comply with the most common standard affecting the reader: NFPA 86.
This column appeared in Heat Treat Today’s2021 Trade Show September print edition. John Clarke is the technical director at Helios Electric Corporation and is writing about combustion related topics throughout 2021 for Heat Treat Today.
John B. Clarke Technical Director Helios Electric Corporation Source: Helios Electric Corporation
To start, we must define our terms. The 2019 edition of NFPA 86* defines a safety shutoff valve as a “normally closed valve installed in the piping that closes automatically to shut off the fuel, atmosphere gas, or oxygen in the event of abnormal conditions or during shutdown.”1 A valve is “normally closed” (NC) if it closes automatically when power is removed. A furnace or oven typically has as few as two or more safety shutoff valves. [Author’s note: If the system uses radiant tubes for heating, and all the criteria are met, it may be acceptable to use only one valve in series, but this exception is not recommended by the author and will not be covered in this article.] There are two common arrangements for safety shutoff valve arrays—the Simple Double Block (Illustration 1) and the Double Block and Vent (Illustration 2). While both arrangements are compliant with the current version of NFPA 86, the vent is NOT required. In other words, Illustration 1 and Illustration 2 below are both acceptable.
The simple double block arrangement consists of two automatic, normally closed (NC) valves piped in series. It provides redundancy—both valves must leak for fuel gas to pass to the burner system. A double block and vent has two automatic, NC valves piped in series with a third automatic normally open (NO) valve installed between the NC valves. The purpose of the NO valve is to provide a path for any fuel gas leaking past the first NC valve to move to a safe location. Whether one should deploy a double block and vent approach depends on several considerations: Is the NO valve supervised? Is the selected vent location safe? And how will the system be inspected?
Illustration 1
Illustration 2
To start with, if the NO vent valve’s coil or wiring fails, it will remain open even when the system is operating—venting fuel gas. This is not only expensive, but high concentrations of vented fuel gas are an environmental and safety hazard. The solution to this concern is installing a monitored vent valve that only opens the NC valves after the vent valve is proven to be closed. This is typically accomplished with a proof-of-closure position switch that only closes after the vent valve is fully closed.
The next concern is the location and maintenance of the vent. The vent must terminate at a safe location that can accept the entire flow of fuel gas in the event of a failure. Therefore, hazards such as fresh air intakes and sources of ignition must be avoided at all costs. It is also important to periodically inspect the vent piping to ensure it remains unobstructed—insects and rodents may find the vent line a comfortable place to nest and bring up their young.
The last challenge is the periodic inspection of the vent valve and the vent piping—it is generally a challenge to test whether a vent line meets the design criteria, and leaking fuel gas can be vented without excessive backpressure.
A simple double block provides redundancy without the complexity of the vent. Good design practice, with proper valve selection, combined with proper fuel filtration greatly improves the reliability and longevity of both systems.
Valves used for safety shutoff valve applications must be listed by an approval agency for the service intended.2 Furthermore, depending on the flow rate, the valves must be equipped with either a local indicator showing the valve position and a means to prove the valve is closed.
For fuel gas flows below or equal to 150,000 BTU/hour, two safety shutoff valves in series will suffice. See Illustration 3 below. This is very typical for pilot lines.
Illustration 3
For fuel gas flows greater than 150,000 BTU/hour and less than or equal to 400,000 BTU/hour, two safety shutoff valves in series with local position indication are required. Local indication is generally a window where an operator can see the actual position of the valve—open or closed—without relying on any electrical circuit or pilot light. See Illustration 4 below.
Illustration 4
For fuel gas flows greater than 400,000 BTU/hour, NFPA 86 requires two safety shutoff valves in series with local position indication. One valve must be equipped with a valve closed switch (VCS) that closes after the valve is fully closed, or a valve proving system (VPS) that runs a tightness check which must be utilized. The signal from either this VCS or VPS must be included in the burner management system’s (BMS) purge permissive string to ensure no fuel gas is flowing during the system preignition purge. The VCS must not actuate before the valve is fully closed. This is typically accomplished by using valve overtravel, where the valve closes first, then the mechanism continues to move until the VCS is actuated. This arrangement is depicted in Illustration 5 below.
Illustration 5
For the arrangement depicted in Illustration 5, NFPA only requires one valve be supervised with a VCS—the additional costs of supervising both valves are very low and will enhance safety.
Whatever the method used to shut off the fuel to burners or pilots, the array of valves must be inspected and tested annually or per the manufacturer’s recommendations, whichever period is the shortest. All systems must be designed to be tested—with provision provided to cycle valves in test mode and the ability to measure any potential leakage. We will explore how a fuel train should be “designed to be tested” in an upcoming article.
The one thing to always remember—safety shutoff valves are always deployed to provide redundancy, so that any one component failure will not prevent a safe interruption of fuel gas; but, as with all systems, there may be unforeseen events that can lead to complete failure. Only qualified people should design, operate, and maintain combustion systems.
References
[1] National Fire Protection Association – NFPA 86 Standard for Ovens and Furnaces 2019 Edition (NFPA, Quincy, Massachusetts, May 24, 2018) 3.3.82.2 pp 86-14.
[2] National Fire Protection Association – NFPA 86 Standard for Ovens and Furnaces 2019 Edition (NFPA, Quincy, Massachusetts, May 24, 2018) 13.5.11.1 pp 86-49.
About the Author:
John Clarke, with over 30 years in the heat processing area, is currently the technical director of Helios Electric Corporation. John’s work includes system efficiency analysis, burner design as well as burner management systems. John was a former president of the Industrial Heating Equipment Association and vice president at Maxon Corporation.
In June, we spent a good deal of time discussing a simple pressure switch to emphasize the many considerations that are necessary for proper installation. Now we will expand the discussion to how the switch works and what steps we can take to detect a failure that is likely to occur sometime in the future.
This column appeared in Heat TreatToday’s2021 Automotive August print edition. John Clarke is the technical director at Helios Electric Corporation and is writing about combustion related topics throughout 2021 for Heat TreatToday.
John B. Clarke Technical Director Helios Electric Corporation Source: Helios Electric Corporation
A pressure switch is a Boolean device — it is either on or off — so how can we evaluate its performance in a manner where a potential failure can be detected before it occurs? The simple answer is time — how long does it take for the switch to respond to the condition it is intended to sense? What is the period between starting an air blower and the pressure switch closing? Has this time changed? Is a change in this time period to be expected, or does it portend a future failure?
A simple approach to evaluating this pressure switch’s time is to create predetermined limits — if the switch responds either too rapidly or too slowly — an alarm is set and the operator is alerted. Graph 1 illustrates this approach.
In Graph 1, the black band represents the time between the action (the start of the air blower) and the pressure switch closing. There is a warning band (yellow) — both high and low — that provides the early warning of a system performance problem. There is also a critical band (red) — both high and low — that provides the point at which the feedback for the pressure switch is determined to be unreliable. If the switch is part of a safety critical interlock, the system should be forced to a safe condition (in the case of a combustion system, with the burner off and a post purge being executed) if required.
Graph 1
Graph 2 depicts when a switch closing time exceeds the warning level. It could be the result of a problem with the blower and/or the pressure switch, but the deviation is not sufficiently large as to undermine confidence in the switch’s ultimate function.
Programmatically, if the time exceeds the warning band, and an alarm is registered, the responsible maintenance person is notified. If that is in the warning band, it can be addressed as time allows.
Graph 2
The warning bands give us the crystal ball to potentially see a problem before it causes a shutdown. As it is continuously monitored by the programmable logic controller (PLC), it may provide an increased level of safety, but that is dependent on a number of factors that are beyond the scope of this article.
The switch can be not only too slow to respond: an unusually fast response is a reason to be concerned as well. It could be that the pressure switch setpoint has been set too low — so low that it no longer provides useful feedback. Graph 3 is an example with an unusually fast response.
If the time is less than the “Critical Low” preset value, the switch’s feedback is determined to be unreliable. In this case, the setpoint may have been changed during a maintenance interval or even worse — the switch may be jumpered (this assumes we have an interlock string wired in series). The critical values are NOT intended to provide forward looking estimates of required maintenance — they are simply an enhanced safety measure.
This scenario assumes that the response of a component is consistent. In our example of a pressure switch monitoring an air blower, we can assume the time the blower required to reach full speed, the time for a pressure rise time in the air piping, and the responsiveness of the switch is consistent. These time intervals may not be consistent. The air supplied to the blower could be sourced from outside the building (temperate climate), which could cause air density changes between a cool, dry day and a hot, moist day. In this instance, what can be done to detect a failure?
An approach where we see fluctuations in the timing even in instances where all the components are operating properly would be to run a moving average of the time based on the last n operations. Then we compare the moving average to the last time and confirm that any change falls within a specific range.
Step 1 would be to average the last n values for the time required for the switch to trip. Then compare this value (ta) to the last time and see if the deviation exceeds the preset values. Let us assume if the time varies by more than 20% a warning should be issued to the maintenance staff.
Now this method will accommodate rapid fluctuations – but if the performance of the component degrades in a near linear fashion, this formula will not detect a premature failure.
An alternate approach would be to execute this routine on the first n cycles, as opposed to continuously updating the average. Using this method, the performance of the specific component is captured. Or this averaging can be executed on demand or based on the calendar or Hobbs timer.
These concepts are far from new, and it has only been because of the recent expansion in PLC memory storage capacity and processing power that it has been reasonable to perform this analysis on dozens of components on a furnace or oven. Remember, it is a shame to waste PLC processing time and memory!
One or more of these approaches, or similar approaches analyzing time, can indeed be a crystal ball that gives us warning of any of a number of potential failures — warning before a system shutdown is required.
About the Author:
John Clarke, with over 30 years in the heat processing area, is currently the technical director of Helios Electric Corporation. John’s work includes system efficiency analysis, burner design as well as burner management systems. John was a former president of the Industrial Heating Equipment Association and vice president at Maxon Corporation.
Last month we began the discussion about the relationship between combustion safety and uptime, highlighting how combustion safety, reliability, emissions, and efficiency are inseparable. This month, we will explore the subject in greater detail and outline a path that can both reduce the risk of an incident and protect the bottom line.
This article written by John Clarke, technical director at Helios Electric Corporation, appears in the annual Heat TreatToday 2021 Buyer's Guide June print edition. Return to our digital editions archive on Monday June 21, 2021 to access the entire print edition online!
John B. Clarke Technical Director Helios Electrical Corporation Source: Helios Electrical Corporation
How many times have we heard the tale about the man with the leaky roof? He cannot fix his roof when it is raining, and the roof doesn’t need repaired when it is not. This story is also applicable to heating system maintenance, perhaps more so than other plant maintenance activities because it so seldom “rains.” Ovens and boilers tend to be very reliable. (This statement is true for equipment operating at low or moderate temperatures, less so for equipment operating above 1832°F (1000°C).) It is exactly when the machine is properly producing parts that the planning for combustion safety, availability, and performance must occur.
The first critical step we must take is to understand that combustion safety, routine maintenance, tuning, and calibration are parts of a larger work strategy. To focus solely on the annual inspection of safety components while ignoring system tuning will not only compromise tuning and efficiency, but also the safety. We have seen how managerial reactions to high profile incidents have caused some firms to dispatch teams to annually examine valves and pressure switches. This effort is highly compromised if it does not include all aspects of system maintenance as well as capturing what is learned each time to improve future inspections and equipment designs. There is data beyond pass and fail that is valuable if we wish to optimize the performance of our equipment
Let us assume it is a clear sunny day, and we are ready to invest some time in preparing to improve our combustion system starting with a deep dive examination of two pressure switches: the low fuel gas pressure switch (LFGPS) and high fuel gas pressure switch (HFGPS). These ubiquitous components are present on nearly every fuel train and are vital for safe operation. As their names imply, they monitor the fuel pressure and shut the safety valves if the fuel gas pressure is either too high or too low.
These switches must be listed for the service they provide by an agency independent of the manufacturer – UL, TUV, FM, etc. Simply looking for a stamp may not be enough; take the time to read the file or standard being applied by the agency and determine if it describes the application. Next, ask if the pressure switch carries the basic ratings expected, like the enclosure rating (Nema or IP). Is a Nema 1 switch operating in a Nema 12 area? Temperature ratings must be confirmed. All too often a component rated for 32°F (0°C) is applied in an outdoor environment in cold climates, or one with a maximum rating of 120°F (50°C) is applied next to the hot wall of a furnace. The component may operate out of specified environmental ranges for some time, but to apply a component in this manner is betting against the house – sooner are later we are going to lose. Ask the people of Texas if the bet against sustained cold temperatures in early 2021 was worth it.
"John Clarke, Technical Director, Helios Electrical The first critical step we must take is to understand that combustion safety, routine maintenance, tuning, and calibration are parts of a larger work strategy"
Next, let us look at the contact(s) rating of the switch and how it is applied to the burner management circuit. More often than not, these switches are in control circuits fused for more current than the contact rating. If the switch rating is too low, the electrical designer has an option to use an interposing relay to increase the current carrying capacity to this device. This relay is an added component, and as such, adds yet another possible point of failure. If the relay is interposed, is it dedicated to this one switch? Multiple devices being interposed by a single relay is prohibited by NFPA 86, for good reason. Is the relay designed to fail safely? That is, will a relay coil burn out or wiring fault close the critical safety valves? Is the wire gauge suitable for the current carried and protection device used?
Next, is the switch mounted in a safe location free from possible vibration or the foot of an eager furnace operator? If the switch must be changed, are clearances provided to perform this maintenance? What is the mean time to replace (MTTR) the component? Is the way the device is wired providing a path for combustible gas to enter the control enclosure and cause an explosion? Flexible conduit, without a means to seal the connection, is a very common error. Use a properly specified cord and consider using some type of connector to terminate the wiring at the switch. A simple 7/8-16 or DIN connector not only provides additional protection from combustion gas getting into the electrical conduit but is also a great benefit when changing the component in a rush and helps to isolate the component’s control circuit during testing and calibration.
Is the pressure switch suitably protected from bad “actors” in the fuel gas? Perhaps soot is present that could foul narrow passages or H2S that could result in corrosion. These are rare conditions, but coke oven gas may not be as clean as purchased natural gas. Do we need to specify stainless steel components? Would a filter make sense to protect the switch and increase the intervals between maintenance?
Finally, let’s discuss pressure ratings. Unfortunately, nomenclature varies by manufacturer. What is the maximum pressure the device can sustain and not fail, i.e., leak fuel gas into the environment? Many switches can experience a pressure surge without risk of leakage, but the high-pressure event will damage the switch internally. It is important when determining if this rating is adequate to consider possible failure modes that might expose the pressure switch to excessive pressure. As a rule of thumb, a pressure switch must be able to sustain a surge pressure delivered to the inlet of the pressure reducing regulator immediately upstream of the device. Think of it this way, if the upstream regulator experiences a failure, the full pressure delivered to this regulator will pass to the pressure switch in question.
Other obvious pressure ratings are the maximum and minimum set points. The pressure switch should be set to trip as close to the middle of the range as possible and should never be set close to either the minimum or maximum setpoint. Is the pressure switch manually or automatically reset after a trip? In general, it is best practice that the LFGPS resets automatically, and the HFGPS requires a reset by the operator. This recommendation is because LFGPS trips each time pressure is removed from the system, and it is generally understood that the system needs fuel to operate. On the other hand, a high-pressure event is exceedingly rare, and the operator should be made aware of this unusual event.
This article has discussed a lot about the simple pressure switch. It appears to be a heavy lift to perform this analysis on every pressure switch in a facility, but take comfort, once the exercise has been completed on the first system, it is much easier to replicate what has been learned to properly assess other systems. We should most definitely insist that our OEM provides this data, in detail, when new equipment is supplied. Why did we review all these specifications? Because I have been around for a while and have seen nearly every one of these errors in the application of pressure switches on operating combustion equipment.
Next month, we will expand on the pressure switch discussion to describe the tune/calibration and testing processes. I hope this deep and specific dive has been of value. If you have any questions or comments, please let me know.
About the Author:
John Clarke, with over 30 years in the heat processing area, is currently the technical director of Helios Corporation. John’s work includes system efficiency analysis, burner design as well as burner management systems. John was a former president of the Industrial Heating Equipment Association and vice president at Maxon Corporation.
Heat treaters know the importance of keeping current with advancing technologies when it comes to combustion. But tragedy can strike if the necessary standards and training aren't in place.
Written by Robert Sanderson P.E., director of business development at Rockford Combustion Solutions, Heat Treat Today is pleased to bring this Original Content article to you this Technical Tuesday.
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Robert Sanderson P.E. Director of Business Development Rockford Combustion Solutions (Source: Rockford Combustion Solutions)
When you hear about large-scale combustion explosions and loss of human life, you wonder how such a tragedy could happen. And, yet, the number one cause of industrial fuel and combustion system explosions is human error. Therefore, the most critical element of every combustion safety system is not a pressure gauge or shut-off valve, but rather knowledgeable, well-trained operators.
Case History
On June 18, 2007, one of two boilers at a manufacturing plant in Tennessee exploded, causing extensive damage to the facility and surrounding area, and seriously injuring one employee. The 2000-built high-pressure firetube boiler was operating concurrently with a second high-pressure boiler to handle the steam demand of plant operations.
Tennessee state officials concluded that there were a number of factors that contributed to the accident: lack of standard training and boiler operation procedures, inadequate boiler attendance and record keeping, inadequate and improper boiler maintenance, and inoperative and improper operating controls and safety devices. As part of its recommendations, officials stated, the plant “should develop procedures for the training and certification of all boiler operators.”
National Fire Protection Association Standards
Training is so critical that the National Fire Protection Association (NFPA) requires that “all operating, maintenance, and supervisory personnel shall receive regularly scheduled retraining and testing.”
The NFPA publishes multiple prescriptive sets of standards to help keep your staff and combustion equipment safe, and each of these standards stress the value of operator training. Among these standards are:
NFPA 54 — National Fuel Gas Code
NFPA 85 — Boiler and Combustion Systems Hazards (> 12.5 MMBtu/hr)
NFPA 86 — Standard for Ovens and Furnaces
NFPA standards apply to new installations and modifications of existing equipment, and some insurance underwriters apply the current standards retroactively. Operations that use heat are nearly limitless, but larger, common combustion applications include pulp and paper processing, tempered glass production, tire manufacturing, paint/drywall/shingle manufacturing, power plants, coating operations, ethanol and asphalt production, wastewater and sewage treatment, plastic bottle manufacturing, college campuses and breweries to list just a few. Understanding and enforcing applicable NFPA standards is paramount to the safety of every business using a combustion or heat treatment system.
Each NFPA standard has hundreds of pages covering the necessities for safe design, installation, operations, and maintenance of the respective equipment. This article gives a cursory overview of NFPA 54, 85 and 86, and provides guidelines to obtain safety training. When it comes to fuel-fired equipment operation, training is literally a life and death issue.
Consider this: The National Board of Boiler and Pressure Vessel Inspectors and the NFPA have identified that 83% of boiler/pressure vessel accidents, 69% of injuries and 60% of recorded deaths were a direct result of human oversight or lack of knowledge. Poor training also leads to production outages that cost millions of dollars in business interruption, supply chain delays, lost orders and competitiveness. Many companies only learn the value of combustion system training after an accident or expensive shutdown has occurred.
NFPA 54 — National Fuel Gas Code
Also known as ANSI Z223.1, the NFPA 54 standard details minimum safety requirements for the installation of gas piping systems, appliances and equipment supplied with LP-gas, natural gas or manufactured gas. Basically, NFPA 54 addresses the "how’s" and "why’s" of:
Piping system design, materials, and components
Piping sizing
Installing pipes, outlets, and inside concealed spaces
Inspection, testing and purging procedures
Installation and venting of appliances.
NFPA 54 is specific; it does not apply to natural gas systems operating at pressures above 125 psi, propane systems operating over 50 psi, gas/air mixes within the flammable range at pressures over 10 psi, and several other types of systems.
Checking pressure gauges on combustion equipment. (Source: iStockphotos.com)
NFPA 85 — Boiler and Combustion Systems Hazards
NFPA 85 gives those involved with large boiler installations and combustion systems the information they need for fire safety compliance, from system design and installation to inspection. Specifically, the standard addresses single burner boilers, multiple burner boilers, stokers, and atmospheric fluidized bed boilers with a fuel input rating of 12.5 million Btu/hr or greater. It also covers pulverized fuel systems at any heat input rate, fired or unfired steam generators, and other combustion turbine exhaust systems.
NFPA 85 offers guidelines as to the strength of a structure, operation and maintenance procedures, combustion and draft control equipment, safety interlocks, alarms, trips, and other related controls that are essential to safe equipment operation.
NFPA 86 — Industrial Ovens and Furnaces
NFPA 86 outlines the safe operation of Class A, Class B, Class C and Class D ovens, dryers, furnaces, thermal oxidizers, and many other heated enclosures used for processing materials. NFPA 86 guidelines set standards as to how industrial furnaces and ovens are to be designed and operated in order to promote safety, with each class of operation organized into four main categories: location and construction, heating systems, operational requirements, and safety equipment. Beyond these basic categories, each class may have unique conditions addressed for distinct hazards, such solvents or special atmospheres.
NFPA 86 specifically states that personnel who operate, maintain, or supervise the oven or furnace shall be thoroughly instructed and trained in their job functions, demonstrate an understanding of safe operation procedures, be kept current with changes in the equipment and operating procedures, and shall receive regular refresher training.
Training your staff to understand and comply with NFPA 54, 85 and 86 standards will minimize the risk of a catastrophic event. In addition, training enhances overall productivity and helps cut costs. For example, having in-house staff with the skills to recognize defects will lead to better fuel efficiency, fewer interruptions, and the avoidance of outages and downtime. And of course, training is a compliance requirement to be completed on an annual basis.
There are four common ways for your staff to obtain training, all of which can meet requirements to varying degrees.
First, attend a combustion workshop. Doing so will offer a more in-depth experience for your staff since workshops typically include hands-on training and face-to-face instruction. Also, you’ll be able to network with combustion safety and design engineers during breaks and lunches. Workshops normally award attendees with the documentation needed to supply proof of completion. They are held on-site at a training facility, or the instructor may go to the customer’s site to train staff on the plant’s fuel-fired systems and what ancillary equipment is required to support its operation.
Second, in this age of COVID-19, utilize online or remote training programs for a smart choice. Pre-recorded webinars are available 24/7, so attendees can learn at their own pace and convenience. Remote live workshops can be broadcast on Zoom, Cisco, Webex or other digital platforms. This lets attendees interact with the instructor and participate in simulations, so they’ll be equipped with the knowledge & skills required to operate combustion systems without leaving their office.
Third, take OEM instruction. NFPA 86 requires manufacturers to provide instruction upon installation of new ovens, dryers, thermal oxidizers, furnaces and boilers. However, OEMs are not required to return to installation sites to educate operators on the newest changes in national and international regulations, or in equipment design. While the OEM’s initial training may suffice to get the new equipment up-and-running, it is not enough to guarantee ongoing safety. If process changes have been made after installation, the original OEM training may be out of date.
Fourth, develop your own program. This endeavor entails an investment in time, research, continuous improvement, and the participation of dedicated team leaders. If you take this path, you’ll likely need to hire outside experts to ensure that the training curriculum encompasses all NFPA requirements including general safety, operation of equipment, and the latest code protocols.
Valve Inspection (Source: iStockphotos.com)
Conclusion: Training is Essential
Human error is the largest cause of industrial fuel and combustion system accidents, explosions, fires and outages. Fuel-fired equipment incidents can be extremely dangerous and necessitate special attention, engineering know-how, experience and especially, training. Understanding and complying with national codes, along with establishing a safety culture, will save lives and improve the competitiveness of any company using fuel-fired equipment.
About the Author: Robert Sanderson is the Director of Business Development at Rockford Systems dba Rockford Combustion Solutions and is a registered Professional Engineer with over 25 years of combustion safety industry experience. Mr. Sanderson has expanded the business to provide standard and custom combustion safety solutions, ventless valve trains, safety inspections, and training.
One of the great benefits of a community of heat treaters is the opportunity to challenge old habits and look at new ways of doing things. Heat TreatToday’s101 Heat TreatTipsis another opportunity to learn the tips, tricks, and hacks shared by some of the industry’s foremost experts.
Today’s tips are the 1 – 2 – 3! They come to us from Dry Coolers with a word on cooling system growth capability; Bloom Engineering Company Inc. on the importance of careful spending; and Rick Kaletsky, Safety Consultant about clear content labeling.
Heat TreatTip #1
Buy a Cooling System Capable of Growth
Plan for future growth. It is more cost effective to provide additional capacity while equipment is being installed. Simple planning for the addition of future pumps (e.g. providing extra valved ports on tanks) and space for heat transfer equipment (e.g. pouring a larger pad or adding extra piers) can save considerable money down the road with little upfront expenditure. Consider installing one size larger piping for the main distribution supply and return; if this is not possible, make sure you can add an additional piping run on the hangers you will install now. Above all, be sure to include all necessary drains, vents, isolation valves, and plenty of instrumentation. These items are critical aids in maintenance, troubleshooting, and future system expansion. (Dry Coolers)
Thinking about future growth will help you choose the right cooling system.
Heat TreatTip #2
Never Go Cheap on These Two Things
There are 2 things in life you should never go cheap on: Toilet paper and combustion equipment! When upgrading or looking at new systems, spend the money to do it right. Designing on the cheap will only lead to operational and maintenance headaches. And trying to reuse the ancient artifacts when upgrading just to save a buck will cost you 10x that down the road. You don’t have to break your budget to do a quality job! (Bloom Engineering Co. Inc.)
Heat TreatTip #3
Container Clarity Counts!
Assure that container label wording (specifically for identifying chemical contents) matches the corresponding safety data sheets (SDS). Obvious? I have seen situations where the label wording was legible and accurate and there was a matching safety data sheet for the contents, but there was still a problem. The SDS could not be readily located, as it was filed under a chemical synonym, or it was filed under a chemical name, whereas the container displayed a brand name. A few companies label each container with (for instance) a bold number that is set within a large, colored dot. The number refers to the exact corresponding SDS. (Rick Kaletsky, Safety Consultant)
Unclear labeling of chemical materials creates a hazardous situation.
Welcome to another episode of Heat Treat Radio, a periodic podcast where Heat Treat Radio host, Doug Glenn, discusses cutting-edge topics with industry-leading personalities. Below, you can either listen to the podcast by clicking on the audio play button, or you can read an edited version of the transcript. To see a complete list of other Heat Treat Radio episodes, click here.
In this conversation, Heat Treat Radio host, Doug Glenn, interviews Carl Nicolia, President of PSNergy, to learn about how applying efficient combustion can drastically improve the performance of your machines. Click below to hear about high value solutions and where we stand in the "evolution" of combustive techniques.
The following transcript has been edited for your reading enjoyment.
DougGlenn (DG): Today's topic is combustion. It is not only an important feature, but also the core to heat treat as the key to high value solutions; that is, according to today's guest, Carl Nicolia (CN), the president of PSNergy. Carl wrote an article that appeared in a recent edition of Heat TreatToday entitled, The Science of Combustion in an Era of Uncertainty. Several of the points Carl dealt with in that article, we'll deal with today. Get ready to read why not all fire is created equal and why your company needs to evolve with the times and take advantage of the recent combustion efficiency technologies.
First page of Carl Nicolia's article from the June Automotive Issue, The Science of Combustion in an Era of Uncertainty: Darwin was right...Evolve or Perish.
DG: Carl, tell us about your background.
CN: I had a great career in larger global businesses - folks like GE and Chrysler Corporation. After that run, I had met several very smart people that had been in the combustion industry for some time and they had some unique ideas on how we could really truly help elevate the performance of heat treating operations. After doing some homework on the industry, the technology, and the opportunity there, we started PSNergy in May of 2013. Since then, we have been helping customers, really throughout North America, solve combustion issues and help deliver productivity to combustion operations. We are primarily focused on radiant tube combustion systems. We do some open fire work as well. The team itself brings over 40 years of combustion experience to the table. We were really formed on innovation around the fundamental sciences, mostly physics and heat treat, and with a huge obsession for customer satisfaction. We really like to take the approach of becoming part of the customer's team, not really being considered an outside resource, but more of a team member with them, and really develop and play for the long term. That's the background on how we got into the combustion industry.
DG: The immediate reason for us talking with you today is because in our June 2020 issue, on page 37, we had a very interesting article or column written by yourself entitled The Science of Combustion in an Era of Uncertainty: Darwin was right, Evolve or Perish. That was the name of the column. A little bit provocative and an interesting column. And, for those who might be reading this at a later point, we are on the, I want to say, the tail end of a Covid-19 pandemic, but some people might say we're in the middle of it. Nonetheless, that's why the article says, “in an era of uncertainty.” I want to talk to you a little about that column. You make this comment in there, and there are a couple of comments I want to ask you about, and then we'll move on to the more substantive stuff. You say, “All fire is not created equal.” This is an interesting comment. What did you mean by that?
CN: Our team has been having a lot of fun with the caveman references and the whole concept of evolution and when we thought about it, it really did apply well, especially in today's times. We won't get into whether we're at the beginning, middle or end of the Covid thing, but thinking about going from fire at the end of a club to modern combustion systems is a huge leap forward. It was a good way for us to think about and highlight the concept that all fire is not created equal. Just because the burners are firing and the furnace is hot, doesn't mean that you're burning efficiently. There is a big difference between well-tuned, well-balanced combustion systems, and not well-tuned and well-balanced. So in that reference, we talk about setting combustion appropriately: getting the right air/fuel ratio can mean the difference between, in a heat treater's case, profitability and loss or high quality and scrap. Balancing that combustion across the entire system can mean the difference in getting customers and providing the turnaround times that they need. Getting that combustion system balanced and tuned, and keeping that system balanced and tuned, are really essential to “getting the most out of your fire,” if you will. So we had some fun with that reference. You will see that carry through some our advertising in the months to come, as well.
(photo source: PSNergy)
DG: You make one other reference to Charles Darwin and a quote that he mentioned. The quote is not all that brief, but I wanted you to comment on it, if you could. It says “It is not the strongest of the species that survive, nor the most intelligent that survive. It's the one that is most adaptable to change. Intelligence is based on how efficient a species became at doing the things they need to survive.”
CN: That's a great quote, and again, we're having a little bit of fun with it, but especially in today's world. I know that many of your readers have been in operation for generations and those companies have found a way to get a little better, a little smarter, every day, every year, and have not gone through Covid-19, but I'm sure other different issues. I think having them focus on what's critical, really making smart investments, these are the type of things that help move their operations forward, help evolve their operation. That's the type of evolution we're talking about.
Evolution to us is small, impactful changes that make a big difference. Although today it might be difficult to imagine, end customers in automotive, construction, and off-highway vehicles are going to be back. And there is going to be pent-up demand. Productivity is going to be an issue in the months ahead. Our end customers, as they come back online and look for suppliers that can meet that rate with high quality and responsiveness, that's going to be a differentiator. And so, we think that thinking about that evolution now is really important. Making the changes now while you can and be responsive when the time comes, is the right move for us; that's the evolutionary piece.
DG: PSNergy, as you've already mentioned, really focuses in on combustion, combustion efficiency, furnace efficiency and that type of thing. On the second page of this article (page 38 in the June 2020 issue), you mention a case study in there where your crew went in and helped a contract commercial heat treater to improve some efficiency. Can you run down through that case study quickly and tell us what you guys were able to do to help them adapt and improve the type of fire they had in their organization?
CN: Sure. And this is a great story, but it is not a unique story for us. We have quite a few of these success stories around our products and services. We had a Midwest contract heat treating company that was interested in the ceramic waste heat recovery inserts. These are patented devices that we design here at PSNergy. They go into the exhaust leg of the radiant tube and they capture that energy that is normally lost out the exhaust, keeping that energy inside the furnace. In the process, it balances the tube temperature and really increases the productivity of the process.
[blocktext align="left"]Their recovery cycle was reduced by 25% ... And in that total cycle, they dropped gas consumption 5% which eventually led to an increase in output of that furnace by 10% ... the total cost to implement this was less than $10,000.[/blocktext]So, in this particular example, it was a 9-ft IQ furnace and it had four U-tubes, probably a pretty typical type of furnace that we might see in a lot of the contract heat treating manufacturers, like your audience. What we did was install inserts in the exhaust legs of the four tubes and then balanced and tuned the system. This entire process took less than one 8-hour shift to finish. As you can see, the results were really impressive. I always like to say at this point, this is not our data, this is customer data. Their recovery cycle was reduced by 25%. Now, a recovery cycle is from the time I close the door to the time I start my controlled cycle. 25% reduction. And in that total cycle, they dropped gas consumption 5% which eventually led to an increase in output of that furnace by 10%. What we love about this, and this is kind of the theme of the article really, is that the total cost to implement this was less than $10,000. This is a perfect example of high value solution. I hate to say 'low cost' because cost is relative, but this is high value. If I can deliver 25% improvement with less than $10,000, or if I can deliver 10% double-digit output increases for less than $10,000, that's a high value solution.
DG: At $2500/tube, and you had four tubes you were 'upgrading,' if you will, that's pretty impressive.
CN: The beauty of this was there were no piping changes, no construction, and no long downtime. By using the patented technology, the new technology that's out there, combined with our tech-enabled services (balancing and tuning), again using the latest in sensing technology and cloud computing, this customer was able to achieve significant performance improvement. What's awesome is that this is a pretty common story for us. When we do this, these are the types of numbers we can achieve.
DG: We kind of skimmed over a little bit about the inserts. Let’s take just a minute and make clear what exactly you're providing as far as the inserts primarily, and the services as well.
CN: The radiant tube inserts, we like to call them ceramic waste heat recovery devices or waste heat recovery inserts, are primarily silicon carbide and they are in a patented configuration that provides significant improvement in delivering energy through the tube into the load. And they do that by being the right material, (silicon carbide has a very high emissivity, having the right shape, where we take advantage of radiant energy transfer to the tube because of the shape of the insert, and having a wide open cross-section which does not put a lot of back pressure on the combustion system; we allow the combustion system to breathe. Inserts have been around for a long time. The big technology improvement here is having the right material and having it in the right configuration to maximize the amount of energy that is delivered in a radiant tube and minimize the effect on the combustion system.
DG: And are these inserts only for U-tubes?
CN: No, they can be applied on any radiant tube. We've applied them on straight tubes (or I-tubes), U-tubes, Trident® tubes, and W-tubes.
DG: You talk in the article about combustion efficiency and furnace efficiency. Can you elaborate on that and the difference between the two?
CN: We think about this relatively broadly. Combustion efficiency is getting the most energy out of the fuel you purchase, and ensure that you continue to get that same level of performance. This is happening at the combustion system level, the burners, if you will. This goes back to achieving optimal air/fuel ratios. And it is so important, yet often overlooked by a lot of people. The difference between 7% excess oxygen in the exhaust and 3% excess oxygen is significant. If you're at 7% excess oxygen, you're delivering 20% less energy to the furnace than you are at 3%. 20% is a huge, huge number. Especially when you're talking about the core process for heat treating operations, making heat. I think often times we forget that in heat treating, combustion is the core process. Anytime we're running through a heat treat operation, you have to have optimal combustion. And there are high value, easily implemented solutions out there that help you maintain and achieve the optimum combustion.
When we think about furnace efficiency, furnace efficiency is what our customers get paid for - getting energy from the combustion system to the product. And how well we do that, in our view, is furnace efficiency. Think about it this way: You could have a perfectly balanced and tuned combustion system (those four tubes on our example furnace can be tuned perfectly), but we can let, in that system, 40% of the energy escape out of the exhaust. So combustion efficiency might be high, but furnace efficiency is not optimal. That's where we think about implementing the ceramic waste heat recovery devices, for example. You could talk about textured tubes or bubble tubes as another example to help you get that energy from the combustion system into the load. Getting more of the energy produced in efficient combustion for that product being processed – that's the name of the game, and that's furnace efficiency as we see it.
DG: You and I were talking about a recent report that came out from ArcelorMittal regarding their “green movement.” Can you recap that, and maybe hit on the ability for small companies to also embrace the technology that some of these bigger companies are able to embrace?
CN: We found this very informative. ArcelorMittal issued their 2019 “integrated report,” where they discuss their corporate responsibility and sustainability initiatives in the US. They have ten sustainability development outcomes, and energy management is one of those ten key outcomes. ArcelorMittal highlighted the development of a low-cost oxygen sensor for furnaces that reduce fuel consumption by allowing plants to see that combustion performance and then tune for optimization. This goes back to our discussion: Furnace combustion performance is the core to these operations, and they're highlighting the value of getting combustion balanced and tuned correctly and keeping it correct.
Not everyone listening and reading, I'm sure, has the resources of ArcelorMittal, so luckily, PSNergy has developed this technology for everyday heat treating operations and any one of us can now apply this. In fact, the same leading edge sensing technology and cloud computing technology is what our service team uses to deliver our combustion engineering services, or balance and tuning, and that is also incorporated into our combustion monitoring and alerting system. We like to call that CMA. And installing CMA on your furnace is like having a dedicated technician taking combustion measurements every day. If something is starting to go out of tune, actions can be taken immediately before furnace performance is affected and alerts can be sent through the system. Daily reports are issued on combustion and so you know combustion is running well. And if it's not, you're deploying resources to get that out.
DG: So this combustion monitoring and alerting system is a cloud-based system?
CN: Yes, it is, but fundamentally, it is a sensor. It's oxygen monitoring and pressure monitoring that is installed on each individual tube of the furnace that records excess oxygen in the stack just as if you would stand there as a technician with a handheld meter, but this is all connected through the cloud which allows it to be accessible, which allows it to store the data for future trend analysis. We've been able to use that tool to identify failing motorized control valves, declining performance on combustion air fans, etc. There is so much that you can see over and above when you're starting to look at data over time versus a single point in time and that's where the cloud piece comes in. It starts with pulling the sample from the right spot in situ from the exhaust and having the highest level of sensing technology available on the oxygen side and then sending all of that up to the cloud for the analysis for the reporting. It basically is a tech standing there taking measurements every day and then you're able to then get a report that says this is where our combustion is, and I can take steps to do that.
DG: I've got a question about that. So you've got 24/7, 365 monitoring of the system, cloud-based, the reports are coming back to the people in the company only – and only to those people that need to know. Are these things that you guys are alerted to so that you call if something goes wrong, or is it basically just held in-house?
CN: It can be either. You have the option of adding our team into it and we can provide input. The one thing we have decided though is any time the system is deployed, we never want to see that system not functioning properly. We keep a close eye on it. The combustion measurements are only a small piece. There are also a lot of help measurements around the system itself, so we're able to keep an eye on the system. If something started to go wrong from a system standpoint, we haven't seen that yet, but if it ever does, we're able to send our technicians out to make sure that you don't get a break in that monitoring.
DG: Have you had any issues with companies being concerned about cybersecurity?
[blocktext align="right"]Get it right and keep it right and then get the most out of the gas that you purchase. Stop throwing away energy. [/blocktext]CN: Not yet. We deal with that in two ways. Number one is that the data we're taking is relatively agnostic. I'm going to see basically pressures and excess oxygen readings and it's not really associated with anything else. Typically, when we get an output through the customer's system, that is usually on the other side of their firewall so the system security is in place and we can have a clean channel out to our cloud. When customers are uncomfortable with that, we'll use cell technology to deliver that, so there is no interconnectivity to their system. We have thought that through. Some customers are more uncomfortable than others, but we've done it both ways, where we've connected through a portal in their system to get out to the internet and then we've also connected through cellular.
DG: Is it possible to have a completely contained system where there is no internet connectivity?
CN: No. Because a lot of the calculations and analysis is done in the cloud. It's not to say that we haven't been asked for that, and we are working on local displays for let's say a technician that just wants to walk up to the furnace and see how things are running; we do have provisions for that as well.
DG: “All fire is not created equal” we know that, so it sounds like PSEnergy has got some good options for people to help improve and maintain not only combustion efficiency but also furnace efficiency. The example you had in the article was for a commercial heat treater, but obviously this also applies to anybody who's doing any type of combustion heating, captive heat treaters, manufacturers or commercial.
What exactly would you emphasize to these manufacturers with their own in-house heat treating, or in the commercials, about the importance of combustion in the heat treating process?
CN: Combustion is really the core of their process. If I could leave you with a message that there are high value easily implemented solutions for achieving and maintaining that optimal combustion, then I think we've given the listeners and readers a little bit of value here. Get your combustion right and keep it right, and then look for that technology that is available out there that can help you get the most out of every BTU that you burn.
DG: Exactly. And the payback is almost a no-brainer in a lot of situations. Obviously, each situation is going to be unique, but the example you gave in the article, the payback was enormously good. It's certainly worth investigating.
CN: It is. It's always worth investigating when it's about achieving more output. When you can achieve more output and ring the cash register more and create more opportunities for selling additional product or new product capacity, those are easier ROIs. If we're just looking at wanting to save fuel, well sure, that pencils out in that case, it's just not the same sort of three-month turnaround or as quick.
In our case, we recommend three areas: Get combustion right and keep it right, with a tech-enabled service team and monitoring. I really wanted to point out, and we've heard this a hundred times– if it's not measured, it's not sustained. The core of heat treating is combustion, yet very few of us actually measure the performance of combustion. We might measure the output (temperature), but we don't measure excess oxygen, which is really the necessary metric to achieve the efficiency. The big steel example there kind of guides us. You should never wonder how well your combustion system is running. You should know with data. That's the core of your process.
So, get it right and keep it right and then get the most out of the gas that you purchase. Stop throwing away energy. Utilize these high value, easily implemented solutions and get the most out of it.
And the piece that we really didn't talk about was- train your team. There are combustion trainings out there. Ours is specifically geared towards combustion and really for heat treating operations, but train your team and talk about a common understanding and a common language around combustion. That dispels a lot of myths around combustion and exposes the team to the latest technologies and best practices.
Lastly, keep reading and listening to Heat TreatToday and Heat TreatRadio because that's the best way to stay informed on the latest technologies. You've got to keep up on it. All kidding aside, it is a really great way, the information that you guys provide is significant towards staying up on the technology.
DG: I appreciate that shameless promotion there. ~chuckles~
If someone wanted to get a little more information, what are you comfortable giving out as far as contact information for people to get a hold of you?
Carl Nicolia, President of PSNERGY, LLC (photo source: Carl Nicolia)
“There was a time when the caveman’s torch was the top end of heat treating technology. We have since learned that all fire is not created equal. Heat treat technology has evolved from fire to combustion and from combustion to efficient combustion.”
Join Carl Nicolia, president of PSNERGY, LLC, as he challenges industry leaders to evolve with viable and proven solutions to achieve combustion and furnace efficiency in this original Heat Treat Today article.
This article appears in the June edition of Heat Treat Today’sAutomotive Heat Treating magazine.
As a technical professional, engineer, and self-proclaimed geek, in times of uncertainty I take comfort in going back to fundamentals. Going back to basic concepts defined by fundamental scientific principles of physics and heat transfer brings us to a point where we know what will happen, and this can give us all some comfort in these uncertain times. We can take comfort in knowing that when we combine the right mix of air and fuel with an ignition source, we will get fire! And as the caveman said, “Fire good!”
There was a time when the caveman’s torch was the top end of heat treating technology. We have since learned that all fire is not created equal. Heat treat technology has evolved from fire to combustion and from combustion to efficient combustion. We have learned how to optimize the delivery of energy produced by fire to achieve remarkable results. There is high-value technology available today (i.e. low cost with high impact) that can be quickly and easily implemented on existing furnaces, regardless of size or age.
Businesses are moving through some of the most challenging times in modern history. Even though a few months ago the economy was booming, we are now being pushed to respond in new and unique ways. Many businesses, though, have existed for generations and have overcome other challenging market conditions. How did they survive? They evolved!
Darwin was right; “It is not the strongest of the species that survives, not the most intelligent that survives. It is the one that is most adaptable to change. Intelligence is based on how EFFICIENT (my emphasis) a species became at doing the things they need to survive.”
Industries coming back online after extended down times and lost production days, are driving new customer demands for quality parts produced faster and cheaper. End customers are executing plans to ramp-up their plants to run at maximum efficiency. They are securing additional critical inventory and capacity from their supply chain. The productivity ante has been raised! Have your operations evolved to meet these demands?
Combustion efficiency and furnace efficiency are the heart of all gas-fired heat treating operations. Combustion and furnace efficiency can mean the difference between profit and loss, high quality and scrap, survival and extinction. Now more than ever, finding low-cost, easily-implemented technologies to increase efficiency is critical to your business’s evolution. Good news: Products and services enabled by revolutionary technology exist today and can improve the efficiency of your business. Because the technology is revolutionary, the implementation is simple.
Case Study
To understand the impact of this type of innovative technology, let’s look at an example from a contract heat treating company with a 9’ IQ box furnace. This batch annealing furnace is heated by four 5” ID x 65” U-tubes with bayonet recuperators. The company installed the latest technology of radiant tube inserts (RTI) into the exhaust legs of the radiant tubes. Once the RTI’s were installed, the combustion system was tuned, utilizing the latest sensing technology. The results are impressive:
Recovery cycle time reduced by 25%
Total gas consumption per load reduced by 5%
Furnace output increased by 10%
Total time to implement this solution was one day. Total cost to implement this solution was less than $10,000. Payback on this installation was less than three months!
Combustion Efficiency
Combustion efficiency is getting the most energy out of the gas purchased and ensuring you continue getting that same level of performance. Most talk about the importance of proper tuning, yet how many recognize the likelihood they are not running optimally today and can quantify the impact? A furnace running just two points out of tune at 5% excess oxygen is delivering 8% less energy to the system. Jump that to 7% excess oxygen and you are throwing away over 20% of the energy. Keeping the combustion system in tune is critical (Figure 1).
Figure 1: Impact of proper combustion tuning. (photo source: Carl Nicolia)
Just like the caveman, gone are the days of running through the burners with a handheld meter once a year, making adjustments based on a single point in time. There are combustion engineering service teams utilizing the latest technology to achieve higher levels of system performance. It is no longer acceptable to take a burner view of combustion: It must be at the combustion system level. If your service team is still working with single handheld meters, it is time to evolve. At a minimum, service teams today should be equipped with the latest sensing technology that allows them to view combustion in entire zones, if not entire furnaces, record data over the range of operation, and store this data for trending and preventive maintenance.
Once the combustion system is tuned, it is necessary to ensure the system stays tuned. Technology that monitors combustion across the entire furnace multiple times per day is available. Utilizing the latest sensing equipment, along with leading edge controls and IIOT technology, these systems seamlessly collect, analyze, and store combustion data and provide simple actionable alerts that keep your combustion system operating at maximum efficiency. Utilizing this type of technology allows you to stay ahead of combustion efficiency in real time and prevent your operation from throwing away profits.
Furnace Efficiency
Getting and keeping maximum combustion efficiency is certainly the first step in your evolution; however, the only thing you get paid for is getting that energy to product. How well the energy provided through efficient combustion is transmitted to the product being processed is called furnace efficiency. Again, there is low-cost, high-value technology available to increase furnace efficiency.
Waste heat recovery technology continues to evolve. Recuperators have been a great first step that many in the industry have incorporated into their systems, but there is more that can be done.
Ceramic inserts are waste heat recovery devices that work alone, or in conjunction with recuperators, balancing the energy delivered across the entire length of the radiant tube, significantly improving furnace efficiency as well as increasing radiant tube life. Recent technological advancements in ceramic insert design and material have increased the effectiveness of ceramic inserts. Additionally, alternative radiant tube designs, such as bubble tubes and textured tubes, help deliver more energy to the product.
Don't let your radiant tube furnace be the caveman of your operations. Take comfort in understanding that all fire is not created equal, and many combustion technology advancements are based in fundamental scientific principles. Get more information on these low-cost and easily implemented technologies available to the heat treating industry today. Recognize that utilizing these revolutionary technologies is the key to evolving your business to measurably higher levels of responsiveness and performance and will allow your business to thrive in this environment.
Will you evolve?
About the Author: Carl Nicolia is president of PSNERGY, LLC, which provides modern solutions to combustion problems, improving equipment life, enhancing productivity, and reducing emissions through smart application of proprietary products, services, and technology.
Do you always feel confident when selecting heat treating equipment? ¿Se siente siempre seguro cuando selecciona equipos de tratamiento térmico?
The heat treating equipment must satisfy a production need and certain metallographic specifications. Consequently, the dimensions of the space where the parts will be placed may be the main factor in the design of the furnace. This is because metals are only capable of heating up to a certain temperature at a rate that is determined by the heating method, geometry, and load arrangement. Only experienced vendors can make the correct calculations to meet the production needs of the project. Be sure to understand the calculations that lead to the sizing of the proposed system.
