Waste-to-energy industries are incineration installations whose gas emissions are limited by strict regulations. To optimize the energy efficiency, protect the environment and ensure the safety of the technical process, the use of reliable and accurate measuring instruments, and gas analyzers is essential.
The central control room is where the incineration plants are monitored and operated.
Based on the output values of each device, the ACC (Automatic Combustion Controller) controls the amount of fuel and air to ensure complete combustion and to suppress the production of toxic gases such as dioxin. It also controls the speed of the movable grate to optimize the combustion position of the waste.
Utilities such as wastewater treatment facilities, water supply facilities, substation equipment, waste loading facilities are controlled by the DCS (Distributed Control System).
An incinerator is a furnace in which waste is burned. Waste transported to a hearth incinerator is burned until it turns to ash. A fixed hearth incinerator consists of a drying hearth, a combustion hearth and an afterburner hearth.
The waste is first transported to a drying chamber to be dried with hot air at over 200 ° C and ignite. Then, the waste is conveyed to a combustion device, the delivery speed of which is controlled to keep the combustion position constant. Finally, in a post-combustion furnace, the waste is burned at a temperature between 850 ° C and 950 ° C in order to prevent the formation of dioxin.
A cooling tower is the equipment that lowers the temperature of the flue gases to 150 °C by spraying water into the flue gases. The temperature of the flue gases during the waste incineration process is above 800 °C. It is then cooled below 250 °C as the gas passes through boilers and pipes. The reason for lowering the temperature of the flue gases is to prevent the resynthesis of dioxin in this temperature zone. Dioxins are generated from frying ash and Cl.
A baghouse filter, also called a baghouse dust collector, contains many fabric filters. The number of filters varies from 10 to several hundred depending on the scale of the installations. A bag filter is capable of filtering particles of about 0.2 µm. When the filtered gas contains dust, slaked lime is added at the same time. Then the slaked lime absorbs chlorine and harmful ash. Passing through all the filters, the gas is cleaned before being emitted through the chimney. As the surface of the filters becomes dusty, it is necessary to remove the dust regularly.
NOX in exhaust gases produces a harmful substance called a photochemical oxidizer in response to ultraviolet light radiation. If the photochemical oxidizer stays in the air and turns into smog, it is called photochemical smog. NOx diffused in the air binds with H2O or 02 to form HN03. This causes acid rain which pollutes rivers and soils. In denitrification equipment, NH3 is added to the flue gases so that the NOx is reduced to N and H20. The catalytic unit has a honeycomb type catalyst which helps NOx and NH3 to bind together. To save energy and reduce costs, it is important to measure the concentration of NH3 and control the amount of NH3 used.