Cement Industry Heat Recovery
Reduced Operating Costs for Cement Factories
Cement plants that have 4 and 5 stage preheaters have a significant amount of available energy that can be recovered from the kiln exhaust. Most also have available energy from the hot air produced in the clinker cooler. By installing waste heat boilers in these hot gas streams, steam can be produced and used to power a generator (producing electricity) or to drive a fan (offsetting electricity consumption). With temperatures in excess of 600°F, these systems can be cost effective.
Customized Cement Kiln Heat Recovery Solutions
Every cement plant has unique characteristics – whether it is the type of fuel fired in the kiln, the number of preheater stages, utility incentives, cost of power – these are different at every plant. As a result, the system design needs to be customized to maximize the benefit for the plant.
Steam-based Systems: Steam is normally the fluid of choice for these systems. There are hundreds of waste heat systems in Europe and Asia using steam. These plants use the steam produced to turn a turbine generator to produce electricity. However, there are times when utility incentives are available for reducing motor driven loads. In these cases, driving ID fans with steam turbines might be a better system design to take advantage of those incentives. In either case, AirClean has designs that can achieve the highest return for the cement plant.
Organic Rankine Cycle (ORC): Organic fluids are used in lieu of steam when energy is available at low temperatures. These fluids boil at a lower temperature, allowing them to be used in lower temperature applications. This makes them useful, especially in the clinker cooler when the exhaust temperature can be quite low. AirClean partners with ORC equipment providers to integrate these systems in the cement plant. While there are considerably less ORC systems installed compared to steam, they are still a viable alternative. AirClean provides design/build turnkey systems to provide guaranteed returns for the cement plant.
- Cement Preheater Heat Recovery
- Clinker Cooler Heat Recovery
In addition to the power which can be produced by capturing the heat from the downcomer, this will also reduce or eliminate the need for dilution air prior to the baghouse. This reduction in air flow passing through the ID fans translates to additional savings with the help of new sheaves or VFD’s. The existing fans can be slowed down, which will substantially reduce the power they require to operate.
Clinker coolers produce large amounts of heated gas, which is typically released into the atmosphere. Waste heat from the preheater exhaust and clinker cooler can be captured to supply low temperature plant heating needs or for power generation, which can reduce purchased power or fuel expense.