If you think pollution control can be very expensive, you may be right. With ever-increasing pressure to reduce emissions of gaseous pollution -- and a company's carbon footprint -- many are choosing to install fume-abatement systems on process exhausts where pollutants are present. In fact, regulations require pollution control equipment for many industries.
The popularity of the thermal oxidization process for pollution control is, for the time being, high enough that it is considered the norm. Some companies have to endure the cost of cleaning exhausts for the environment. That is the responsibility element companies have to get used to. But it doesn't have to be all bad news.
Process exhaust heat recovery can offer exceptional payback. An industrial-grade, air-to-air heat exchanger -- correctly designed, engineered and built for an application -- can reduce the negative impact on the environment and your operational energy costs.
For instance, suppose you have a regenerative thermal oxidizer (RTO) abatement system. You know the final outgoing oxidizer exhaust temperature is higher than the incoming process air temperature. So, if, for example, you have 200° F (93° C) air entering the oxidizer from your process, the oxidizer exhaust air temperature could be as high as 400° F (204° C) or even higher if the bypass is open. When oxidizers are purchased with high thermal efficiency expectations, companies may overlook the energy recovery potential.
What's Coming In?When looking at energy recovery for industrial thermal applications, first concentrate on where you are pulling fresh air into your process (the fresh air or cold process air inlets) because those places present real opportunities for energy recovery. Much of the cold air pulled into your process could be preheated using the exhaust from a boiler or oxidizer, or even from the process exhaust itself.
Therein lays a win-win opportunity: the same BTUs can be used for both fume preheating for pollution control and energy savings through secondary heat recovery. The win-win is available for OEM and end user processes in industries like printing, paint drying, varnish drying, curing, metal finishing, paper, gypsum, pharmaceuticals, milk drying and plastics.
With natural gas prices as volatile as they have been, this topic certainly warrants some attention. Gas prices may fall a little in the short-term, but the trend is unquestionably up.
Reducing the Cost of Environmental ResponsibilityCountless process engineers have found that by incorporating a gas-to-gas heat exchanger into the oxidation system, the exhaust can be preheated, raising the temperature to the point where the burner has little more to do than give the temperature a boost. This can represent a tremendous reduction in the amount of energy used by the burner. In the case of pollution control equipment such as thermal oxidizers and catalytic oxidizers, this is without a doubt essential.
But, what if you do not need pollution control equipment on your exhaust? With mandates to reduce operating costs, it still makes sense to look seriously at using a heat exchanger to recover heat from the exhaust air and gases and turn it into usable energy for your process. A competent thermal engineering team knows how to match the right design, size and material to fit each application. A correctly sized and specified heat recovery system can deliver increased efficiency and impressive payback. On some applications, it is possible to achieve payback in as little as three months.
Automotive Industry Led the Way. "General Motors was the first auto manufacturer to recover process exhaust," explains Ron Leon, national automotive industry manager for combustion solutions provider Eclipse Inc., Rockford, Ill. "That was back in the 1970s. Then Chrysler and Ford saw the wisdom in investing in heat exchangers. Now, you can't find an automotive manufacturer who's not utilizing this powerful technology."
What is it that the automotive industry saw that caused them to invest in heat recovery during a fairly unstable economic time? Payback. They saw the ability to capture process exhaust and use it to drive the very manufacturing processes it came from -- and dramatically reduce energy costs.
They also saw the opportunity to be environmentally responsible. Even though the topic of environmental responsibility was fairly young in the 1970s, the automakers saw in heat recovery a win-win proposition. It's a tough decision when times are tough. No one would argue that. But, they have realized such tremendous payback, they've multiplied the decision over and over, until every possible process has incorporated a heat recovery system.
Hang on to Your CashThere isn't a plant manager in North America who hasn't been challenged to reduce operating costs. An effective heat recovery system can be a key component in that successful effort. To look at heat recovery only makes good fiscal sense. While it may not be easy to let go of your company's capital during hard economic times, does it really make sense to hang on to a dollar for three, six or twelve months when, at the end of that time, that dollar could be paying you $2 or $3 every year in return, for more than 10 years down the road? That, of course, is for you to decide.
One important thing to remember is that once the initial capital expenditure has been recuperated, heat recovery projects provide ongoing savings in the terms of cost reductions year after year. It's important enough to mention again: When a heat exchanger has been correctly engineered and built, depreciation can be based on terms of 10 years or more.
Imagine a world where no one overlooks the potential for reducing pollution -- and for heat recovery.
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