RU2453770C1 - Combined ash catcher - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: proposed device comprises filtration element and moving packing working in fluidised bed mode. Set of elements arranged along gas flow comprises cyclone, apparatus with circulating fluidised layer and return cyclone, filtration ceramic element. Disperse particles with capillary-porous structure and size, at least, one order larger than that of ash particles fed with gases from cyclone into apparatus are fluidised. Gas velocity in said apparatus is defined subject to dancing of said particles, their capillary-porous structure being filled with ash particles so that their averaged bulk density makes, at least, 50% of ash density. Particles capillary-porous structure filled with ash particles are drained from layer bottom while these new particle are added to the layer.

EFFECT: improved design.

1 dwg

Description

The invention relates to the field of power engineering, in particular to boiler plants burning solid fuel.

Known combined ash collector installed in a boiler with a fluidized bed under pressure [1], in which the cyclone is used as the first stage, and a ceramic filter is used as the second stage.

A disadvantage of the known combined ash collector is the increased load of ash collection on the ceramic filter. Since the maximum cyclone efficiency does not exceed 95%, the ash remaining in the gases after the cyclone will be captured in a ceramic filter. This will necessitate a more frequent regeneration of the ceramic filter and ultimately reduce the reliability and efficiency of the combined ash collector.

Closest to the claimed ash collector is a filter dust collector Sh.V. [2] containing a filter element and a movable nozzle, which is in the process of working in the fluidized bed mode.

The disadvantage of this filtration ash collector is the increased wear of the filter element and the elements of the movable nozzle during the impacts of the elements of the movable nozzle on the surface of the filter element. This leads to a decrease in the efficiency and reliability of the ash collector.

The technical result of the claimed invention is to increase the reliability and efficiency of gas purification from ash in a combined ash collector.

The inventive combined ash collector has a three-stage design: a cyclone for the primary collection of ash particles, an apparatus with a circulating fluidized bed and an integrated return cyclone and a ceramic filter. The gases that have undergone preliminary treatment in the first stage - the cyclone, enter the fluidized bed apparatus. To create a movable nozzle, dispersed particles with a capillary-porous structure and size not less than an order of magnitude higher than the weighted average size of dispersed ash particles carried by gases from a cyclone are also fed into the apparatus. The gas velocity in the apparatus takes on a value calculated according to the conditions of the flow of capillary-porous particles, the capillaries and pores of which are filled with dispersed ash particles so that the density of these particles is not less than 50% of the ash density. The capillary-porous particles removed from the layer are sent to the recovery cyclone, captured there, and then returned to the layer. The gases purified in the apparatus after the return cyclone are final cleaned in a ceramic filter.

Combined ash collector operates as follows. Gases together with dispersed ash particles come from the boiler furnace to a cyclone, in which, due to the action of centrifugal forces, the gases are preliminarily purified from dispersed particles with an equivalent diameter exceeding about 40 microns. Smaller dispersed particles of ash and layer material are carried out by the gas stream from the cyclone and enter the apparatus with a circulating fluidized bed. In the apparatus as dispersed particles forming a fluidized bed, particles having a capillary-porous structure, which are fed into the layer, are used. In the apparatus, the lifting motion of capillary-porous particles and dispersed particles of ash is carried out by a stream of gases with different speeds. This leads to the fact that due to the uneven flow of particles with a capillary-porous structure, the flow of gases carrying particles of ash, capillaries and pores of the particles are filled with ash particles and held in this position. Capillary-porous particles filled with dispersed ash particles and unable to be held by the flow of gases in suspension are lowered into the lower part of the layer and merged from the layer. Capillary-porous particles, which under the conditions of soaring move with the gas flow upward, at the outlet of the apparatus enter the return cyclone. In the return cyclone, capillary-porous particles are separated from the gases and returned to the lower part of the apparatus with a fluidized bed, and the gases are sent to a ceramic filter for final cleaning.

The analysis of technical solutions carried out by the applicant in similar constructions using available sources of information did not reveal analogues that are characterized by the entire set of essential (or identical) attributes inherent in it. Revealed the closest analogue of the claimed ash collector allowed us to highlight the set of significant in relation to the applicant specified technical result of the distinguishing features set forth in the claims.

Therefore, the inventive combined ash collector meets the eligibility condition "novelty."

An additional search by the applicant for known solutions in related fields did not reveal the prominence of using the distinguishing features of the claimed ash collector to solve the same or similar problems. This proves that the claimed ash collector does not follow for specialists explicitly from the prior art.

Since for the practical use of the inventive combined ash collector there are no obstacles of a technical, technological or other order, the inventive ash collector meets the eligibility condition "industrial applicability".

A specific example of the implementation of the inventive ash collector installed behind the boiler with a fluidized bed under pressure is shown in the figure. The gases leaving the furnace 1 of the boiler with a fluidized bed under pressure enter cyclone 2, in which the gases are preliminarily purified from ash particles. Particles of ash trapped in the cyclone are returned to the furnace or fed to the hopper 8. From cyclone 2, gases as a fluidizing agent are supplied to the apparatus with a circulating fluidized bed, including the apparatus 3 itself and return cyclone 4. As a movable nozzle forming a layer in the apparatus use dispersed particles with a capillary-porous structure and a size not less than an order of magnitude greater than the size of the ash particles. Particles with a capillary-porous structure are fed into the layer from the hopper 6 through the gateway 9 or poured from the layer through the gateway 9 into the hopper 7. The dispersed particles with the capillary-porous structure captured in the return cyclone are returned to the layer, and the gas previously purified from ash fed to the ceramic filter 5. In the ceramic filter, the final gas purification takes place.

Combined ash collector operates as follows. Dispersed particles of ash and material of the layer of fractions 0 ÷ 4 mm, removed from the furnace of the boiler with a fluidized bed under pressure and having a temperature of 850 ÷ 900 ° C, are sent to the cyclone. In a cyclone, due to the action of centrifugal forces, gases are 90% purified from coarse ash fractions with a size of at least 40 μm. Coarse ash particles trapped in the cyclone are returned back to the boiler furnace or discharged into the hopper, and gases carrying small suspended ash particles are sent to the apparatus with a circulating fluidized bed in which they play the role of a fluidizing agent. Dispersed particles having a capillary-porous structure and size no less than an order of magnitude higher than the weighted average particle size of the ash are fed into the apparatus as a movable nozzle. The size of the capillaries and pores of the particles corresponds to the size of the particles of ash removed from the cyclone. In an apparatus with a circulating fluidized bed, the gas velocity is set at a level exceeding the rate of movement of particles with a capillary-porous structure. (So, the calculations [3] show that for dispersed particles with a diameter of 30 mm and having a density of 50 kg / m ³ liquefied by gases with a pressure of 1.2 MPa at a temperature of 850 ° C, the speed of movement is 3.2 m / s.) In the process of lifting movement in the apparatus of particles with a capillary-porous structure, an uneven flow of these particles through a gas stream carrying ash particles occurs. In this case, dispersed ash particles penetrate into the capillaries and pores and are held there. Particles with a capillary-porous structure carried out from the apparatus enter the recovery cyclone, from which they return back to the apparatus. During the circulation of particles with a capillary-porous structure through the apparatus and the return cyclone, these particles are saturated with ash. As a result, at a certain critical value of the density of particles with a capillary-porous structure, which is at least 50% of the ash density, the gas flow is no longer able to hold these particles in suspension. As a result of this, these particles will be concentrated in the lower part of the apparatus, forming a fluidized bed itself. For continuous operation of the apparatus, these particles are discharged from the layer through the gateway into the storage hopper. The gases that have been cleaned in a circulating fluidized bed apparatus are sent to a ceramic filter, in which the final gas purification is performed. At the same time, the quality of gas purification meets the requirements established for the purity of gases supplied to gas turbine plants.

Thus, the use of the claimed invention allows to purify gases having a high temperature and pressure from dispersed ash particles, while ensuring high quality cleaning for a long period of time. As a result of this, the reliability and efficiency of the combined ash collector are increased.

Literature

1. Gas-turbine and combined-cycle plants of thermal power plants: a textbook for universities / S.V. Tsanev, V.D. Burov, A.N. Remezov; under the editorship of S.V. Tsaneva. - 2nd ed. stereotype. - M.: Publishing House MPEI, 2006, pp. 538-540.

2. Patent RU 2035207. Filtration dust collector Sh.V.

3. Calculations of fluidized bed apparatus: a Handbook / Ed. I.P. Mukhlenova, B.S. Sazhin, V.F. Frolov. - L .: Chemistry, 1986, pp. 243-245.

Claims (1)

Combined ash collector containing a filter element and a movable nozzle operating in a fluidized bed mode, characterized in that the combination of ash collector elements along the gas makes up a cyclone, a device with a circulating fluidized bed and a recovery cyclone, a filter element in the form of a ceramic filter, in a device with a circulating fluidized bed dispersed particles having a capillary-porous structure and a size not less than an order of magnitude larger than the size of the ash particles are fluidized by a bed supplied for gas cleaning; falling with gases from the cyclone into the apparatus, the speed of gases in the apparatus is determined from the condition of dispersed particles with a capillary-porous structure soaring, the capillaries and pores of which are filled with ash particles so that the average bulk density of the particles is at least 50% of the ash density, dispersed particles , the capillaries and pores of which are filled with ash particles, merge from the bottom of the layer, and new particles with a capillary-porous structure are added to the layer.