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Contenido archivado el 2022-12-27

IMPROVED CYCLONIC PARTICULATE REMOVAL EQUIPMENT FOR USE WITH COAL-FIRED INDUSTRIAL BOILER PLANT

Objetivo

To demonstrate, at full scale, the technical and economic viability of improved designs of inertial separators for use with a coal fired boiler plant. Cyclones do not result in energy savings. Their advantage is that the lower capital cost of the gas cleaning package will result in the total coal fired boiler package being more competitive with alternative liquid/gaseous fuels.
The commercial demonstration of the Mk VII cyclone has now been completed with 5,700h of operation (+/- two years of normal industrial usage). For this period the cyclone controlled flue gas solids levels well within UK statutory limits. The only problem throughout the demonstration period was a single blockage within the VCP 1, resulting from failure of the grit removal system.
At the termination of the demonstration, metal thickness measurements were taken by ultrasound, and show that metal errosion continued to be low except in areas of high dust loading, especially in the entry annulus and in the solids exit from the main cell.
Errosion rates in terms of mm metal loss/10,000h, even in the more susceptible region of the cyclone continued to be less than 2mm. As the utilisation of industrial boilers is typically 40%/y, 10,000h operation represents three years normal industrial use. Therefore measurements indicate that metal wastage is likely to be acceptable for this type of cyclone in industrial coal-fired boiler applications.
Due to the inaccessibility of the inner components, the knife edges, weir and the main cell throat, wear on these components was not measured during the demonstration period.
Laboratory support studies at the University College Cardiff, and have re-examined scale-up criteria by measuring collection efficiencies for Mk VII cyclones. Analysis of data obtained from cyclones with outer tube diameters of 30 to 600 mm illustrated the effects of scale-up. For outlet tube diameters up to 300 mm, a scaling factor of 10, the performance data falls onto one common curve: however, beyond this size, there is no agreement. Deviations are especially large for the sub 5 micron particles, adding to the predicted deterioration in particle separation performance obtained from the Sprint 4 computer models and laser anemometry measurements on the 30 mm outlet tube size perspex cyclones.
It is felt that these effects are related to specific design features of the Mk VII type Cardiff cyclone, namely:
- the VCP
- the vortex weir
- the flat bottom centre section
To assess the effect of the weir, cyclones with and without inlet weirs were tested, and the one without the inlet weir achieved higher collection efficiencies especially for sub 10 micron particles. This work resulted in the development of the Mk VIII cyclone (VCP Concentrator).
This device has an scroll inlet (for higher gas flow capacity per unit pressure drop) and a single VCP. Its compact size and simplicity of design makes it ideally suited to industrial applications.
Phase 1 : performing, testing and modification as necessary, to novel cyclone installed at the Coal Research Establishment, commencing June 1, 1984
Phase 2 : long term demonstration of installation, as commissioned under Phase 1, commencing October 1, 1984, to be completed mid-1986 Phase 3 : covers construction, installation and commercial demonstration of second novel cyclone : planning commenced late 1985.
The first cyclone to be demonstrated is the novel Cardiff MK VII cyclone developed at University College, Cardiff under support from the Science and Engineering Research Council and National Coal Board.
The measurement programme consists of the following :. measurements of solids separation performance by determination of mass
flows and size distributions of cyclone catchments and stack solids. variation of above, with gas throughput. wear characteristics. reliability of operation. capital and maintenance costs
The principal measurement is of cyclone metal thickness against hrs on stream, especially for high risk areas. Operational temperatures and pressures drops are also recorded for several positions in the demonstration cyclone system.
Cardiff cyclones incorporate Vortex collector pocket (VCP) technology which exhibit better particle separation, reduced choking tendency, smaller unit size and improved operational flexibility over a wide range of gas flows in comparison with conventional designs of similar throughput.
Rotating dust laden gases in the cyclone body induce, by viscous drag, a contra rotating gas Vortex in the VCP which overlaps the cyclone body. Particles within the gas flow are thrown towards the cyclone walls and, at the overlap with the VCP, proceed tangentailly under their own inertia, passing into the VCP.
Then, falling away under gravity, they are removed via a rotary valve. This differs from the "shave-off" type device in that there is no net gas flow between the main cyclone and the VCP, obviating the need to clean a secondarygas stream.
Total project costs are projected at UKL 350,600.
A major component breakdown prevented completion of a commissioning programme on the 2. 8 MW water tube boiler to which the 2nd Demonstration Cyclone is attached. The Mk VIII cyclone has sufficient technical merit to warrant demonstration, and will be fitted to a 2. 5 MW (8,400 lb/h) shell boiler in the CRE Test Boiler House Facility. The boiler is a 2. 4 m in diameter, of overall 6. 6 m length and fitted with a vibrating grate stoker.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

BRITISH COAL CORPORATION (RESEARCH ESTABLISHMENT
Aportación de la UE
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Dirección
COAL RESEARCH ESTABLISHMENT STOKE ORCHARD
GL52 4RZ CHELTENHAM
Reino Unido

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Coste total
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