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IEE . Enviromnental Info. 40f9 J , I " { ;~ http://www.ieeco.comlenviron2.htm 18000 F) before they are allowed to exhaust to the atmosphere. In many installations, retention time is insufficient to meet current standards. Increasing the afterchamber's volume increases the likelihood that the exhaust gases will be sufficiently exposed to these temperatures, thereby reducing the amount of pOllutants exhausted to the atmosphere. Maintaining Adequate and Steady Temperatures Adequate and steady temperature levels are virtually important to maintaining the quality of exhaust gases. Typically, the desired range of operating temperatures is from 14000F to 18000F depending on local environmental requirements. In cremation, temperatures higher than 18000 F are not necessarily better for pollution control and can, in fact, create more pollution. When the temperature in the cremation equipment exceeds the designed level, the body burns faster and the exhaust gases expand to a greater volume. This overloads the afterchamber, which then cannot destroy the pollutants as quickly as they are being produced. Unfortunately, this results in higher emissions of pollutants. low chamber temperatures can be just as much a problem. If temperatures are too low, the pollutants entering the afterchamber will not be suffICiently combusted. low temperatures reduce the effectiveness of the afterchamber to destroy particulate matter and convert gaseous pollutants to a less harmful gaseous exhaust. Therefore, proper controls to maintain adequate and steady temperature levels are important. Turbulence Turbulence is created in the crematory exhaust flow by physical obstacles such as baffles and perforated walls, which cause the exhaust gases to twist, turn, change directions and squeeze their way through the passages in the system. This forces the exhaust gases to mix thoroughly with the oxygen introduced into the system, while exposing them to the temperatures maintained in the afterchamber. As with temperature, too much turbulence can cause other problems. Some of these problems are overheating of the cremation chamber and the puffing of smoke out of the charging door at the entrance to the cremation chamber. Controlling Controlling usually refers to the ability of a device to measure process variable (temperature, opacity, CO, 02) compare it to a desired setpoint specified by the operator, and take action to maintain the setpoint. The device can automatically perform the action, such as adjusting a valve position, as necessary to alter the equipment's operation. These devices often display the selected set point as well as the actual level of the process variable. More sophisticated control equipment may also have the ability to record on paper the action being taken to maintain the process variable, and send this information to a computer and printer. Wet Scrubbers A wet scrubber is an add-on pollution control device attached to the cremator exhaust stack. It is similar to a large shower with an entrance and an exit. Exhaust gases from the cremator are ducted into the wet scrubber, where they are subjected to water sprayed from different directions by several nozzles. Water droplets capture the particles or solids in the 8111018:04 AM