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.
Ernesto Perez, Director of Engineering, Nutec Bickley
In today’s Heat Treat TodayTechnical Tuesday feature, Ernesto Pérez, Director of Engineering, at Nutec Bickley, introduces readers to different options when it comes to furnace temperature control.
The main aim of the temperature control function is to keep a furnace operating within certain predefined values and it is composed of two main parts:
Electronic control element, usually a PID (proportional–integral–derivative) controller
Mechanical components
In this article we will look at the various control modes used in industrial furnaces, and their applications for various heat treatment processes.
Back to the Beginning: “Zero Control” Mode
Figure 1
Before considering the modes currently used, we should briefly mention the “zero control” mode found in earlier furnace models, employed some time back, also known as “atmospheric mode.”
This mode operates by taking air from the environment by means of the venturi effect to perform combustion without controlling the air flow, resulting in an inefficient use of energy. (Figure 1)
Fuel-Only Control System
Figure 2
This operates in a similar way to zero mode, where only the gas is controlled. However, instead of the air being introduced by the venturi effect, there is a turbo fan that provides a constant flow to the process, while the gas is regulated during the different stages of combustion. (Figure 2)
Economic system having a single line of control.
It provides good temperature uniformity in applications where all items being fired in the furnace need to be at the same temperature.
Ideal for low temperature furnaces, kilns for ceramics and applications that require high-level heating homogeneity.
Possible Disadvantages This technique leads to high gas consumption due to the heating of all the air present, irrespective of the size of the load in the furnace.
Proportional Control System
Figure 3
With this control mode, the air and the gas are controlled proportionally. (Figure 3)
The operation starts with a small flame, and as the temperature rises, it grows as the air and gas levels increase.
This system allows you to adjust the amount of gas based on the air present in order to achieve perfect combustion and optimal fuel consumption.
Ideal for any type of furnace, for example for heat treatments such as aging, tempering, forging and normalizing.
Possible Disadvantages At the beginning of the heating process, it can be the case that temperature uniformity across the entire furnace is not so good due to the small flame, so it is not a system recommended for the treatment of very fragile pieces that can break.
Mass Flow Control System
Figure 4
This system controls air/gas in the same as the previously described method, but it also gives allowance to vary the air/gas ratio during combustion process in order to optimize the fuel. (Figure 4)
It enables for the achievement of optimal combustion conditions with less energy input.
If more air is needed in a particular heat treatment stage (usually at the beginning), it can be temporarily increased.
Ideal for any type of furnace, like heat treatments such as aging, tempering, forging, normalizing and applications involving fragile products.
Possible Disadvantages Because of the technology behind the system, it is more expensive.
Pulse Control System
Figure 5
This is one of the most recently introduced methods that provides a fixed air/gas ratio, but unlike the previous mentioned systems, flame velocity for product heating is always high, which generates ideal temperature uniformity right from the beginning of the cycle. (Figure 5)
The burners pulse from high-fire to low-fire, repeating this cycle every 15 to 60 seconds.
It is cheaper to operate than the mass flow system, allowing users to handle the entire range of products with a smaller investment.
It provides greater fuel efficiency by heating the product evenly from the beginning.
Ideal for any furnace, for example for heat treatments such as aging, tempering, forging, normalizing and applications involving fragile ceramic products.
Possible Disadvantages The radiation of the flame can affect certain products; however, by installing an additional instrument it is possible to control this effect and to reduce flame radiation.
Experts in Temperature Control
Nutec Bickley can offer all current systems, advise on the most appropriate choice with the best cost benefits, update old systems with current technology, and provide repair and spare parts services for existing temperature control systems.
About the author: Ernesto has been sharing his expertise at Nutec for 18 years. As an electronic system engineer with a master’s degree in artificial intelligence, the 25-year industry veteran has been focused on the control aspect of software and hardware.
Climate change and fossil fuels are topics that can spur many lively conversations. In today’s Heat Treat TodayTechnical Tuesday feature, explore their connection as it relates to heating industrial furnaces in the future with Dr. Joachim G. Wüenning, president, WS Inc. and an expert in clean efficient combustion.
Many people view climate change as the biggest threat to mankind. Technical and social efforts will be required to meet the goals, formulated in the “Paris Climate Agreement,” to limit global warming to less than 35.6° F (2° C).
Combustion of fossil fuels is by far the largest human contribution to global warming. Fossil fuel-fired power plants and internal combustion engines are already in the public focus. The transformation to alternative drives for vehicles has just started, and the days of coal-fired power plants are numbered.
Combustion of fossil fuels for industrial furnaces is also a large contributor to greenhouse gases and air pollution. The industrial heating sector is not in the public focus yet, but that will change soon; therefore the topic should be addressed proactively.
For mid- to long-term future industrial process heating, there are three main scenarios:
heating with renewable electricity, or
heating with non-fossil fuels, or
a combination of both.
Humans used non-fossil fuels for hundreds of thousands of years and are returning to that habit after a short period of about 250 years where fossil fuels were primarily used.
Reducing CO2 Now and In the Future
Heating a furnace using electricity is locally CO2 free, but an even greater amount of CO2 is emitted at power plants since the majority of electricity is generated by burning fossil fuels. For every kilowatt hour (kWh) produced, roughly one pound (~0.45kg) of CO2 is emitted into the atmosphere [1]. This is true for Germany, and the figures for the United States are in the same range.
Heating an industrial furnace with a typical temperature of around 1832°F (1000°C) with natural gas produces about 0.4kg CO2 for every kWh of available heat for a cold air burner, and less than 0.25kg/kWh CO2 when using a recuperative or regenerative burner where waste heat is recovered using a heat exchanger.
So, the short-term measure to reduce CO2 emissions is to use an efficient burner with heat recovery or to switch from electric to natural gas heating, which can cut CO2 emissions by 50% or more.
For a further reduction, we have to wait until electricity generation becomes predominantly regenerative, or we have to use green, non-fossil fuels. The possible paths to non-fossil heating of industrial furnaces are drafted in Figure 1. It shows that the short-term action should be improving the efficiency of burner systems or a switch from electric to gas heating. In the mid- to long-term future, there should be a healthy competition between non-fossil fuel gas and electricity, driving the prices for non-fossil energy down.
Figure 1
Changing Fuel Compositions
The most relevant characteristic for the interchangeability of fuel gases is the Wobbe Index (Figure 2), with the lower or upper heating value (Hi, Hs), the density of the fuel gas (r) and the density of dry air (r0). Fuel gases with the same temperature, pressure, and the same Wobbe Index will provide the same energy output from a burner. If the Wobbe Index is changing, the flow must be corrected by changing the fuel gas pressure or a flow throttle device to keep the burner power constant.
Figure 2
In most cases, the air does not need to be corrected since the ratio between stoichiometric air ratio and lower heating value is about 0.95 m3/kWh for common hydrocarbons. That means that a burner with a given heating power needs the same amount of air even when different fuel gases are used. A good rule of thumb is that one cubic meter per hour of air is required for every kilowatt of heating power.
If hydrogen is used as a fuel, about 15% less air is required. So, when hydrogen is added to natural gas and the fuel gas flow is corrected but the air flow is left unchanged, the system would be operated with somewhat more excess air, slightly less efficient but safe.
If gas fluctuations will occur in the future, adjusting the burners with more excess air would be an easy measure to ensure safe operation. With an effective heat recovery system and low exhaust gas temperatures, efficiency losses would be minimal.
Fuel Gases With High Hydrogen Content or Pure Hydrogen
The flame speed of hydrogen is much faster compared to hydrocarbons. That can cause some problems, especially in premixed burners where a flashback can occur. Another challenge resulting from faster combustion could be higher flame peak temperature leading to higher thermal NOx emissions. Modern low NOx methods are available to address this problem.
A positive effect of hydrogen can be a more reliable and easier ignition of burner systems. Many industrial burner systems can be operated with high percentages of hydrogen or with pure hydrogen with little or reasonable modifications.
Fuel Gases Containing Fuel Bound Nitrogen
Using ammonia or bio-gases with fuel bound nitrogen will produce excessive amounts of NOx-emissions when burned in most burner systems. There are a number of options to achieve low NOx-combustion with fuel bound nitrogen.
One method is fuel conditioning where fuel bound nitrogen is broken up into molecular nitrogen. This was successfully demonstrated using a stainless steel reactor in combination with a flameless oxidation burner system.[2] Another method would be exhaust gas cleaning by selective (SCR) or non-selective (SNCR) catalytic exhaust gas cleaning. Both processes require large investments and operating costs and should only be used if other options are not available.
The development of combustion systems with integrated treatment of fuel bound nitrogen would be the preferred method and will be an important topic for combustion research in the coming years. One approach is multi-stage flameless oxidation [3].
Fuel Conditioning
Fuel conditioning might be required to keep fuel gas properties within regulated limits inside the gas transport and distribution grid or for certain customers with special requirements. Fuel conditioning can be performed by blending different gases or by changing their compositions by using reformers or gas separation units like pressure swing adsorption (PSA) or membrane technology.
If future regulations propose a certain hydrogen content in the fuel gas grid, strategically placed steam reformers could keep the hydrogen content within certain ranges, even if there is no regenerative electricity available to operate electrolysers.
Reformers could also crack ammonia, ethanol, or methanol before being used as fuel gas to heat processes.
Outlook
There are several options towards non-electric, fossil-free industrial process heating. All these options have to be thoroughly investigated to keep a number of options open for future energy systems. The energy system of the future will be based on regenerative power generation but it will involve additional energy carriers to store and transport the energy. There are some challenges for combustion but there is no doubt that these can be overcome.
A fair and open competition between the different energy options will create the best solutions for society and the planet. A planned economy will not provide the fertile soil for innovations and entrepreneurship necessary to meet the challenges.
References
[1] German Environment Agency, CO2 Grid Emission Factors from 1990 – 2018 for the German Energy Mix, March 2019
[2] Domschke T., Becker C., Wüenning J.G., Thermal Use of Off‐Gases with High Ammonia Content – a Combination of Catalytic Cracking and Combustion, Chem. Eng. Technol., 21: 726-730
About the Author: Joachim G. Wüenning is president of WS Wärmeprozesstechnik GmbH and his area of expertise is in clean efficient combustion, FLOX—flameless oxidation, heat recovery, radiant tubes, and recuperative, regenerative burners. This article originally appeared in Heat Treat Today’sMarch 2020 Aerospace print edition.
This article on the critical role of valve safety trains in the prevention of catastrophic fuel-delivery accidents at heat treating facilities is authored by Robert Sanderson, P.E., Director of Business Development in the Combustion Safety division of Rockford Systems, LLC, based in Rockford, Illinois. Valve safety trains require regular inspections, maintenance, and training.
Heat treating, a thermal process used to alter the physical, and sometimes chemical, properties of a material or coating, is a high-temperature operation that involves the use of heating or chilling, normally to extreme temperatures, to modify a material’s physical properties — making it harder or softer, for example. Applications for heat treating are virtually endless, but at the heart of all thermal processes is the valve safety train.
These fuel-delivery devices maintain consistent conditions of gasses into furnaces, ovens, dryers, and boilers, among others, making them crucial in assuring safe ignition, operation, and shutdown. Equally important, they keep gas out of the system whenever equipment is cycled or shut off.
A valve safety train isn’t a single piece of equipment. Instead, it has many components including regulators, in-line strainers (“sediment traps”), safety shut-off valves (SSOV), manual valves (MV), pressure switches, and test fittings logically linked to a burner management system.
Flame-sensing components make sure that flames are present when they are supposed to be, and not at the wrong time. Other components may consist of leak-test systems, gauges, and pilot gas controls. At a minimum, there are two crucial gas pressure switches in a valve safety train, one for low pressure and one for high pressure. The low gas pressure switch ensures the minimum gas pressure necessary to operate is present. As you would assume, it will shut off fuel to the burner if the gas pressure is below the setpoint. The high gas pressure switch ensures excessive pressure is not present. It too will shut off fuel if the gas pressure is too high. Both switches must be proven safe to permit operation. Additionally, there will be an air pressure switch to ensure sufficient airflow is present to support burner operation.
Some systems have supplementary pressure switches, such as a valve-proving pressure switch. Switches such as these are typically used to enhance safety or provide other safety aspects specific to that application’s needs. A multitude of sensors within the valve safety train — pressure switches, flame detectors, position indicators — and isolation and relief valves work together in concert to prevent accidents.
Valve safety trains must be compliant with all applicable local and national codes, standards, and insurance requirements. The most common of these for North America are NFPA, NEMA, CSA, UL, FM. Annual testing and preventive maintenance are not only an NPFA requirement, but also oftentimes required by insurance agencies, equipment manufacturers, and national standards, including ANSI, ASME, and NEC.
Set Your Trap
The primary function of a valve safety train is to reliably isolate the inlet fuel from the appliance. Safety shut-off valves are purposely selected to do this. To protect these valves, the initial section of a safety train is used to condition the fuel and remove debris that could potentially damage or hinder all downstream safety components.
The first conditioning step is a sediment trap (a.k.a. dirt leg, drip leg). This trap captures large debris and pipe scale and provides a collection well for pipe condensates. The proper orientation of a sediment trap is at the bottom of a vertical feed. This downwards flow arrangement promotes the capture of debris and condensate into the trap. A horizontal feed across a sediment trap is an improper application. The second conditioning step is a flow strainer or filter element. These devices are fine particulate sieves. The removal of fine particulates from the fuel stream further protect the downstream safety devices from particulate erosion and abrasion. Taken together these conditioning steps remove particulates and condensates that might block, hinder, erode, or otherwise compromise the safety features of the downstream devices.
The Explosive Force of a Bomb
Owing to the presence of hazardous vapors and gases, a poorly designed or inadequately maintained safety train can lead to catastrophic accidents, ranging from explosions and fires to employee injuries and death. When this explosive force is unleashed, the shock wave carries equipment, debris, materials, pipes, and burning temperatures in all directions with tremendous force.
The following incidences provide just a few examples of why it is important to purchase the highest quality valve safety train and to keep it professionally maintained, inspected, and tested.
In 2018, a furnace explosion at a Massachusetts vacuum systems plant killed two men and injured firefighters as a result of fuel malfunction.
In Japan, an automobile manufacturer lost tens of millions of dollars when it was forced to shut down production for nearly a month after a gas-fueled furnace exploded due to flammable fumes building up in the tank.
In a Wisconsin bakery, an employee was seriously injured when he ignited an oven’s gas and was struck by a door that was blown off. A malfunctioning valve had allowed natural gas to build up inside the oven.
In 2017, a van-sized boiler exploded at a St. Louis box company, killing three people and injuring four others. The powerful, gas-fueled explosion launched the equipment more than 500 feet into the air.
In 2016, a boiler explosion in a packaging factory in Bangladesh enveloped the five-story building in flames, killing 23 people.
Two Dangers: Valves and Vents
Valves are mechanical devices that rely upon seats and seals to create mechanical barriers to control flow. Over time, these barriers wear out for a variety of
Glassblowing Furnace with Pipes
reasons, whether it is age, abrasion, erosion, chemical attack, fatigue or temperature. Increased wear contributes to leaks, and leaks lead to failures and hazards. Defective valves can allow gas to leak into a furnace even when the furnace is not in operation. Then, when the furnace is later turned on, a destructive explosion could occur.
Testing a valve’s integrity is an evaluation of current barrier conditions and may be used to identify a valve that is wearing out prior to failure. As such, annual valve leakage tests are an important aspect of a safety valve train inspection program. Along with annual testing, valves should be examined during the initial startup of the burner system, or whenever the valve maintenance is performed. Only trained, experienced combustion technicians should conduct these tests.
Improper venting is another danger. Here is the problem: Numerous components in a valve safety train require an atmospheric reference for accurate operation. Many of these devices, however, can fail in modes that permit fuel to escape from these same atmospheric points. Unless these components are listed as “ventless,” vent lines are necessary. Vent lines must be correctly engineered, installed, and routed to appropriate and approved locations. In addition, building penetrations must be sealed, pipes must be supported, and the vent terminations must be protected from the elements and insects. In short, vent lines are another point of potential failure for the system.
Even when vent lines are properly installed, building pressures can vary sufficiently enough that they prevent optimal burner performance. Building pressures often vary with seasonal, daily weather, and manufacturing needs, further complicating matters. Condensate in vent lines can collect and drain to low points or into the devices themselves. Heating, cooling, and building exhausters are known to influence building pressures and device responses, but so can opening and closing of delivery doors for shipping and receiving. Hence a burner once tuned for optimal operation might not be appropriately tuned for the opposite season’s operation.
The smart alternative to traditional vented valve trains is a ventless system that will improve factory safety and enhance burner operation. Ventless systems reference and experience the same room conditions where the burners are located, resulting in more stable year-round operating conditions, regardless of what is happening outside. Additionally, ventless designs typically save on total installation costs, remove leaky building penetrations, eliminate terminations that could be blocked by insects, snow or ice, improve inspection access, and ensure a fail-safe emergency response.
Final Thoughts
Valve safety trains are critical to the operation of combustion systems. Despite being used daily in thousands of industrial facilities, awareness of their purpose and function may be dangerously absent because on-site training is minimal or informal. To many employees on the plant floor, this series of valves, piping, wires, and switches is simply too complex to take the time to understand. What is known can be dangerously misunderstood.
Understanding of fuel-fired equipment, especially the valve safety train, is necessary to prevent explosions, injuries, and property damage. The truth is, although valve safety trains are required to be check regularly, they are rarely inspected, especially when maintenance budgets are cut. And while codes require training, they offer very little in terms of specific directions.
As a safety professional, the onus is on you. You and your staff must have a core level of knowledge regarding safe practices of valve safety trains, even if a contractor will be doing the preventive maintenance work. Most accidents and explosions are due to human error and a lack of training when an unknowing employee, for example, attempts to bypass a safety control. Preventive maintenance is essential to counter equipment deterioration, as is the documentation of annual inspection, recording switch set points, maintaining panel drawings, and verifying purge times. Accidents happen when this type of documentation is not available. Don’t wait for a near-miss or accident to upgrade your valve safety train.
During the day-to-day operation of heat treat departments, many habits are formed and procedures followed that sometimes are done simply because that’s the way they’ve always been done. One of the great benefits of having a community of heat treaters is to challenge those habits and look at new ways of doing things. Heat TreatToday‘s 101 Heat TreatTips, tips and tricks that come from some of the industry’s foremost experts, were initially published in the FNA 2018 Special Print Edition, as a way to make the benefits of that community available to as many people as possible. This special edition is available in a digital format here.
Today, we offer one of the tips published under the Combustion category.
Combustion
Heat TreatTip 50
Effect of Exhaust Gas Temperature vs. O2 on Efficiency
Tuning a burner properly is important for safety. Tuning can also have a significant effect on efficiency in some but not all cases.
The efficiency of a conventional cold air burner varies significantly with the amount of excess air (related to % O2 in the exhaust products). Since a cold air burner does not use the exhaust gas to preheat the combustion temperature, the exhaust gas temperature is essentially equal to the furnace temperature. For a cold air burner operating at a 1,850°F, reducing excess air from 20% to 10% (reducing O2 from 4% to 2%) will increase efficiency by almost 5%.
Modern high-efficiency burners use the exhaust gas to preheat the combustion air as it enters the burner. Therefore, the temperature of the exhaust gas leaving the burner is significantly lower. The lower the exhaust gas temperature, the smaller the effect of a change in excess air on efficiency. For example, a self-regenerative burner operating at 1,850°F may have an exhaust gas temperature around 480°F. In this case, reducing excess air from 20% to 10% (reducing O2 from 4% to 2%) will only increase efficiency by about 1%.
As a general rule of thumb, reducing exhaust gas temperature by 180°F will increase efficiency by about 5%. So while proper tuning is important for many reasons, it does not have a significant effect on the efficiency of burners with advanced heat recovery systems.
During the day-to-day operation of heat treat departments, many habits are formed and procedures followed that sometimes are done simply because that’s the way they’ve always been done. One of the great benefits of having a community of heat treaters is to challenge those habits and look at new ways of doing things. Heat TreatToday‘s101 Heat TreatTips, tips and tricks that come from some of the industry’s foremost experts, were initially published in the FNA 2018 Special Print Edition, as a way to make the benefits of that community available to as many people as possible. This special edition is available in a digital format here.
In today’s Technical Tuesday, we continue an intermittent series of posts drawn from the 101 tips. The category for this post is Combustion, and today’s tip is #23.
Combustion
Heat TreatTip #23
Burner adjustment to nominal gas and air ratios is a typical component of your combustion equipment maintenance. However, this process cannot be minimized in importance as any adjustment can affect operation, efficiency, exhaust emissions & equipment life. Factors to consider and address during any burner adjustment:
Burner adjustment should always be done when possible at normal furnace operating temperature under typical production to maintain best conditions for final calibration.
Provide clean combustion air: maintain blower filter & consider the source of any plant air.
An increase of gas may not increase power to the system due to heat transfer or throughput issues.
A decrease in combustion air will not create a hotter flame or add power to the system as this may only create a gas-rich operation resulting in reduced power and CO in the exhaust.
Verify gas & combustion supply pressures & consider creating a monthly log of incoming pressures.
While a visual inspection of flame can help to verify operation or proper combustion, burner gas /air adjustment can not accurately be performed by simply looking at color or size of a flame.
A working understanding of burner system is important to determine and verify values to gas/air and excess O² to a specific application.
If you have any questions, feel free to contact the expert who submitted the Tip or contact Heat TreatToday directly. If you have a heat treat tip that you’d like to share, please send to the editor, and we’ll put it in the queue for our next Heat TreatTipsissue.
Running a heat treat shop is more than just firing up a furnace to treat components; it’s doing so in a way that is both efficient and safe.
Today’s Technical Tuesday is a helpful article from Control Engineering about burners for gas-fired heat treating furnaces, their differences and how they are best utilized in different heat treating applications, technological advances in controls engineering, and combustion safety. The article draws on the skills and knowledge of several in the industry who have contributed to the advances and development in burner manufacturing, operation, and safety.
A couple of excerpts:
“With a careful engineering analysis, it often is possible to obtain more efficiency by optimizing either process or system control. As an added benefit, in many cases, such optimization does not require substantial physical hardware upgrades.” ~ Michael Cochran, marketing engineer, combustion systems at Bloom Engineering Company Inc.
“The goal of both regenerative and recuperative designs is to capture heat energy that would otherwise be wasted.” ~ Control Engineering
Nico Schmitz, Christian Schwotzer, and Herbert Pfeifer with the Department for Industrial Furnaces and Heat Engineering (IOB) in Germany have collaborated on an analysis of metallic recirculating radiant tubes, their purpose in the heat treating process, and their design and installation. In particular, the authors, with access to a furnace-equipped pilot plant operated by IOB, investigate the factors that affect tube productivity and contribute to tube failures. They have reported on these findings in an exclusive paper published at heat processing online, the official publication of the European Committee of Industrial Furnace and Heating Equipment Association (CECOF).
An excerpt:
“It is common to assume a homogeneous temperature distribution for construction calculations. In real operation, inhomogeneous temperature distributions occur. The temperature gradients induce thermal stresses that can substantially influence the lifetime of the tubes. In addition to that, higher furnace temperatures come along with an increasing thermal load.”
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 Treat Today’s 101 Heat Treat Tips is another opportunity to learn the tips, tricks, and hacks shared by some of the industry’s foremost experts.
