How to Build a Waste Heat Recovery System Tailored to Your Business

When one thinks of wasted resources, the mind tends to picture certain things: sheet metal, wood, food stuffs, etc. We tend to pigeon hole ourselves into very physical representations of “waste” and focus on mitigating lost profit through eliminating these sources of physical waste. And while this is a valid approach towards waste mitigation and efficient plant management, there are less corporeal forms of waste that can also be addressed. 

Waste Heat, for example, runs rampant in a manufacturing industry that runs on large pieces of machinery that generate massive amounts  of heat — heat that could be repurposed into energy for other processes within a factory! 

Before you disregard these claims as bogus, a study performed by researchers at UC Berkeley just 3 years ago found that the US consumes an average of 100 quadrillion Btus of energy in a given year and, of those Btus, as much as 60% of that energy is dissipated as waste heat.

So, what is waste heat? And, even more importantly, how can that heat be repurposed into usable energy with hardware such as heat exchangers and industrial grade computers? 

What is Waste Heat

To make an abstract term a little more concrete, “waste heat” is energy (heat) produced during the industrial process that is not used in any productive capacity and is then wasted into the environment.

As we mentioned, this waste heat can be produced across many disparate steps during manufacturing. Radiation from industrial equipment, heat discharged from combustion processes, even heated water and steam being expelled are all examples of energy that could be repurposed with the right waste heat recovery system. 

What is Waste Heat Recovery

 A waste heat recovery system, like the name aptly implies, is a system designed to capture this wasted heat and use it to generate electrical or mechanical power or even be reused for other processes that require heating. 

As an example, consider the average furnace in a steel working plant. The furnace heats incoming materials and, in the process, emits heat that is dissipated from its walls and openings. This heat is also often thrown out into the environment through chimneys and smoke stacks. With a waste heat recovery system, a heat exchanger is installed which, instead of sending this heat out into the atmosphere, uses it to perform other tasks such as pre-heating combustion air needed to burn fuel like liquid propane. Many times, this heat can even be recycled and used to heat incoming air that is then pumped back into the furnace, prolonging its operation without needing to waste money on energy needed to heat incoming air.

Unfortunately, as impressive as this sounds, not all heat can be repurposed and converted into usable energy. Higher temperatures of waste heat conventionally provide more energy when repurposed, meaning manufacturers that perform processes that only give off low levels of heat may not see a return on their waste heat recovery investments. 

Thus, there are a few recommended practices inherent to both learning whether your facility gives off enough heat to even warrant building a waste heat recovery system and building said system.  

Building a Waste Heat Recovery System

Building a waste recovery system requires three key things. Firstly, you need to know what kind of heat you’re dealing with — what temperature, how often it’s being produced, and when/where it’s available. All of these variables will have a direct impact on how you build your waste heat recovery system (and may even rule out building one in the first place). 

Secondly, a heat exchanger like the one we mentioned in our furnace example is the tool that will actually perform the capturing and repurposing of heat. There are several types, each fit for different types of manufacturers, and picking the right one is essential to building a waste heat recovery system that provides value. 

And finally, you’ll need a plan for what to do with that waste heat once it has been captured.

Track and Define Your Waste Heat

There is a surprising variety in the types of heat that are produced in any given industrial process. Depending on your industry, heat can be given off as steam, heated water, combustion, etc. Not only that, heat can be produced in a variety of temperatures that determine just how viable it is for use in other areas of production. 

All that said, having industrial hardware capable of reading and reporting temperatures and heat dissipation is an absolute requirement. Thankfully, IoT enabled hardware with sensors able to pick up on these readings are in no short supply within manufacturing. As far as the workstations that house this data, you’ll want to ensure they are built industrial-grade and rugged since they will be deployed near machinery that give off waste heat and debris.

Something like an IP65 certified HMI Interface is highly recommended since it is properly fortified against moisture ingress which can be a common issue for waste heat recovery systems. Steam and heated water are very common forms of waste heat and these workstations will be deployed near the machines that give off this moisture, making these certifications even more essential to the heat recycler than they already are to manufacturers as a whole.    

Pick the Right Heat Exchanger

Once you’ve determined where in your facility usable heat is being wasted and what temperature of heat waste you’re dealing with thanks to your industrial grade panel PCs and sensors, you can pick a heat exchanger best fit for capturing and repurposing that specific grade of heat.

Just like waste heat, there is a surprising amount of variance to be observed in heat exchangers. Picking the right one for your operation specifically becomes much easier once you’ve done the legwork of defining your heat waste like we mentioned in the previous step. ScienceDirect has a wonderful resource that breaks down the multiple types of heat exchangers, how they work, and what industries they are the best fit for. We highly recommend checking that resource out once you’ve defined the kind of waste heat recovery system you wish to build.   

Have a Plan for Your New Heat Energy

Now that you have this new resource in your grasp, deciding what to do with it to maximize efficiency and profit is the logical next step.

Let’s return to the example of the furnace. Heat captured from that furnace with a waste heat recovery system can be used for a dozen different use cases. It could be captured and used to heat incoming air that is then pumped back into the furnace, making its own operations more efficient. That same heat can also be diverted to an industrial boiler in order to aid in the boiling process. What matters most is picking the use case that best benefits your bottom line. 

Where is there fluctuation in available heat that’s causing you to invest in more electrical energy? Can the new heat you’ve captured be used to supplement these practices? Is there a way to divert your newly captured waste heat to a different process that seems to be struggling? These are all questions you can ask and answer by consulting with your IoT sensors and smart hardware. And once you’ve found answers for these questions, you can ensure you build a waste heat recovery system designed to meet all of your individual pain points. 

Before You Start, Make Sure Waste Heat Recovery Systems are Right For You

Many times, when we discuss new methods of smart manufacturing and industrial tech, we speak about innovations such as artificial intelligence, collaborative robotics, predictive maintenance, things that all industries and manufacturers can benefit from. With waste heat recovery systems, however, it’s important to truly understand whether your business can profit from it before starting investment. Pay attention to the grade of heat your factory floor wastes. Not only that, consider how many operations in your facility are tied specifically to heat as a resource. If you’re only wasting very low grade heat, you aren’t really losing a potent resource that can benefit your business. And if you only have one tangential process that is tied to heat as a resource, you may not receive the return on investment you think you will implement a waste heat recovery system. 

All that said, for those who know waste heat is a significant concern for their operations, the benefits of capturing and repurposing that heat can’t be understated as we see more and more manufacturers embracing lean, green efforts to prepare for more tumultuous times in the industry. For more information on the hardware needed to build these waste heat recovery systems, contact an expert from Cybernet’s team today.