Environmental considerations for preheater design

In June 2002 the new MACT (Maximum Achievable Control Technology) rules will go into effect. These new rules represent the tightest emissions regulations to date and will have an effect on new and upgraded cement production lines hereafter. The MACT rules do not regulate NO_x or SO₂ and CO is only regulated when firing waste fuels; however, each state regulates these emissions for a new cement production line. It is important to note that states can mandate even lower limits than those given in the MACT rule and add additional emission requirements. As the emission limits get tighter and tighter, it becomes critical to be able to accurately predict gaseous emissions and incorporate the proper system design to meet permit requirements. A number of possibilities exist to minimize gaseous emissions. These include systems designs, like the low NO calciner, and "tailpipe" designs, like the wet scrubber. Some methods are much simpler and less expensive than others. In some instances the viability of a new production line can depend on the extent of added costs required to achieve environmental compliance. This paper focuses on emissions of NO _x SO₂, CO, and THC, and the various methods that can be used to control these emissions within current limits