Overview
Waste storage, preparation and incineration in waste incineration
Instruments for waste reception and combustion
The waste collected for incineration is stored in a waste bunker. Odors escaping from the bunker are prevented by keeping the bunker at a slight vacuum, by taking the combustion air for the boiler out of the bunker section. Pre-mixed waste is fed by crane to the feeder hopper, then via a chute to the inlet section of the boiler grate. The staged combustion takes place in the different zones of the grate. It is controlled by the primary air flow to the different zones of the grate. The grate is air or water cooled. Oil or gas burners exist to ignite and supplement the combustion process. Spray water is used to control the temperature in the gas path as well as the temperature in the steam pipes in order to control the steam temperature. Slag/ash is removed by the furnace bottom ash receiver which cools the ash and seals the furnace vacuum against the environment with water. Measurement of bulk solid materials is not a trivial task; uneven surfaces, different moisture levels and high levels of dust reflect only some of the challenges. KROHNE pioneered radar level measurement technology for process applications and today offers a broad range of sophisticated FMCW and TDR based technologies for level measurement of liquids and all kinds of solids - for almost every application.
The OPTIWAVE-series are FMCW radar level meters for liquids and solids, with operating ranges from 6 to 80GHz. The patented drop antenna at the OPTIWAVE 6400 securely avoids dust build-up that can occur in metallic horns, and drastically improves the reliability and availability of the instrument. This is very useful for dusty environments. In the area of waste storage and preparation, OPTIWAVE 6400 and OPTIWAVE 6500 are used within the entire handling chain, including the waste bunker, during the transportation via conveyor belts and in the waste hopper, where the instrument is often used to replace older level meters based on nucleonic technology.
The OPTISONIC 7300 ultrasonic gas flowmeter measures the natural gas flow for ignition, or supplemental burners, giving immediate response to flow changes. It also works without moving parts and consequently is maintenance free. With a high turndown ratio the flowmeter is suitable for measuring low load and high flex operation and virtually measures down to zero flow. It is unaffected by frequent starts/ stops of the flow - which was not the case with older flow technologies.
The bottom primary air flow through the different combustion zones of the grate needs to be controlled. OPTIBAR DP 7060 C with a 10 mbar cell is ideally suited for this low dP application as it is fully 3D-factory linearized over a wide dP, static pressure and temperature range offering superb long term field performance for any dP-Flow application. The grate is air or water cooled. The flow of the cooling medium needs to be monitored by an OPTIFLUX 2000 magnetic flowmeter for water or an OPTISWIRL vortex meter for cooling air.