Obiettivo To burn efficiently a wide range of types of coal (high volatile lignites, bituminous coals, anthracite coals) in run-of-mine small sizes difficult to use commercially (0-15 mm), with high content of ashes and sulphur, in small equipment which must operate automatically, and able to be installed in the premises of a very ample range of users with low energy needs: small industries, public buildings.Further innovative aspects :Easy start-up procedure; no need to build up the fluidised bed prior to start-up; few fixtures needed.Vey low pressure drop in the combustion chamber as only a small bed of ashes is accumulated.Stable combustion at start-up in spite of lack of a stabilising inert bed; efficient use of coal dust by solids recirculation.Adequate desulphurization reached by a thorough blending and recirculation of calcium-containing additive.Low NOx emissions reached by means of low temperature maintained in the combustion chamber, and two stage combustion air injection.The overall results are satisfactory. The main issues are:Both lignite and bituminous coal were used successfully. The feed size was in the range 0 to 7 mm. This means that run-of-mine coals or refuse products from coal preparation operations can be used in this process.Low NOx and SO2 emissions were achieved, in compliance with German Regulations for Emissions to Air. Rhine lignite with low sulphur content and high Ca and Mg content could be used without need of additive.The plant operates under full automatic control, just like an oil or gas plant, excepting of course ash removal which must be made periodically by manual means.Several important modifications and ajustments had to be made to the plant after the initial tests. The problems encountered were related to the positioning of the secondary air nozzles, the emissions of SO2 were slightly increased by two-stage combustion, the oil startup phase was rather long due to insufficient thermal insulation. This can be corrected in the future.In summary, the SFBC boiler technology is ready to be replicated at the 400/500 kW size, and ready to be demonstrated at larger sizes, such as 2500 kW (th).Coal is normally burned in three ways; grid firing, pulverised coal firing or fluidised bed combustion (FBC). The pulverised coal system has the advantages of good heat transmission, high specific capacity. The FBC has the advantages of controlled NOx and SO2 emissions.The Small Fluidised Bed Combustion (SFBC) aims at obtaining most of the advantages of the two other mentioned technologies. The SFBC was tested first at laboratory scale (100 kW -th), and was then scaled to industrial size (400 kW-th) in this project. The main features are : a Fluidised Bed Combustion chamber, surrounded by an annular space serving as a recirculation/heat control device, a spiral-shaped heat exchanger heats up secondary air. A pre-heating chamber receives all combustion air, and is fitted with an oil burner which heats the boiler prior to coal feed. The boiler start-up takes place automatically without need of intensive human attendance. The combustion device is separated from the heat recovery device, operation is thus more effective and less prone to failure (heat exchanger tube damage). The combustion temperature, 1.050 deg. C, is higher than the usual FBC temperature (about 900-950 deg. C). This has heat transmission efficiency advantages.Hot gas is recirculated to improve combustion efficiency and SO2 absorption by calcium-containing additive. Downstream the combustion chamber, a filter removes particulate matters, prior to releasing flue gases to the stack. The feed coal and limestone additive are stored in a storage bin, from which a screw conveyor feeds the boiler.All the system is operated under automatic control.Other outstanding features of the SFBC :Simple design : there are no complicated arrays of fuel injection nozzles or heat exchange areas in the fluidised bed.Stable combustion; this is obtained through several devices in the reaction chamber and the recirculation loop.High desulphurization ratio through intensive additives blending and recirculation. Programma(i) ENG-THERMIE 1 - Programme (EEC) for the promotion of energy technology in Europe (THERMIE), 1990-1994 Argomento(i) 7.1 - ATMOSPHERIC FLUIDIZED BED COMBUSTION Invito a presentare proposte Data not available Meccanismo di finanziamento DEM - Demonstration contracts Coordinatore GERHARD PRUEFLING GMBH Contributo UE Nessun dato Indirizzo PFISTERMEISTERSTRASSE 53 8450 Amberg Germania Mostra sulla mappa Costo totale Nessun dato
