RU2259240C1 - Method for purifying gas from dust - Google Patents

Abstract

FIELD: processes for purifying of gas from dust in heat engineering, ferrous and non-ferrous metallurgy.

SUBSTANCE: method involves introducing gas to be purified into cyclone provided with axial discharge branch pipe for gas to be purified; purifying gas from dust by the action of centrifugal forces upon progressive motion of rotating gas flow from the top to the bottom, followed by turning of purified gas flow upward; supplying flow of auxiliary wetted gas into zone where purified gas flow turns in upward direction; introducing solid coagulant such as natural snow mass or chipped ice or mixture thereof into gas flow in an amount of 0.1-10.0 kg/m³ of gas under purification process. With an increase in dustiness of gas under purification process, consumption of natural snow mass, chipped ice or mixture thereof per each 0.2 g/m³ of gas is increased by 0.5-1.0 kg/m³ of gas under purification process.

EFFECT: increased extent of purifying gas from dust.

1 dwg, 1 tbl

Description

The invention relates to a technology for cleaning gases from dust in the power industry, ferrous and non-ferrous metallurgy.

A known method of cleaning gases from dust, which consists in the tangential supply of dusty gas, cleaning gas from dust due to the action of centrifugal forces, separating dust from gas in the sweep of the purified gas (see Dust collection in metallurgy. Reference book / V.M. Aleshina, A. Yu. Waldberg, G.M. Gordon et al., M.: Metallurgy, 1984, p. 48-52). The disadvantage of this method is the low efficiency of the dust collection process.

The closest in technical essence and the achieved result is a method of cleaning gases from dust, including introducing a gas to be cleaned into a cyclone with an upper axial exhaust pipe, cleaning gas from dust due to the action of centrifugal forces during the translational movement of a rotating stream from top to bottom with a turn of the cleaned stream up, supply a solid coagulant is introduced into the reversal zone of the auxiliary humidified gas stream, while a solid coagulant is introduced into the compressed gas stream (see Patent No. 2091175, Russia, IPC 6 В 04 С 5/18, 1997).

The disadvantage of this method of gas purification is the low degree of gas purification from dust. This is due to the low specific surface area of the coagulant solid particles. It contains a small number of pores, protrusions, hooks and other irregularities, which reduces the coagulating ability of mineral solid particles. Moreover, it is difficult to utilize the resulting sludge.

The objective of the invention is to increase the degree of purification of gases from dust.

The problem is solved in a method of cleaning gases from dust, including introducing a gas to be cleaned into a cyclone with an upper axial exhaust pipe, cleaning gas from dust due to the action of centrifugal forces during translational movement of a rotating stream from top to bottom with a turn of the cleaned stream up, supplying an auxiliary stream to the reversal zone humidified gas, wherein the gas stream is introduced into a solid coagulant, which is used as natural snow ground or crushed ice or a mixture thereof in an amount of 0.1-10.0 kg / m ³ of gas to be purified, wherein m with increasing dust purified gas per 0.2 g / m ³ of their flow is increased by 0.5-1.0 kg / m ³ of gas to be purified.

The essence of the invention is to use as a coagulant natural snow mass, ice crumbs and mixtures thereof. Snow mass and snow-ice mixture are located in the Russian Federation in the form of natural precipitation and snow cover for 7-11 months. Moreover, the calendar time for finding the snow mass coincides with the heating season, during which there is a need to clean the flue gases from dust at communal and domestic boiler houses, TPPs using coal and brown coal as fuel. The stocks of snow mass in winter are practically inexhaustible, its cost is minimal and is due only to the cost of its transportation to steam generators. The main advantage of the snow mass is its high coagulating ability. Particles of snow mass have an exceptionally developed surface, replete with tiny ice strands, cobwebs, and hooks, which are an effective mesh trap (filter) for dust particles. A feature of dust coagulation by snow particles is the possibility of trapping particles not only by the surface of snow lumps, but also by their deep layers. This happens when the captured dust particle has a higher speed and it penetrates into the body of the snow particle to a greater depth.

Since the snow mass is in the negative region of the temperature scale, the interaction of hot particles and cold snow mass forms a water shirt on the surface of the snow particles, which forms capillary adhesion forces between adjacent solid particles, enhancing the coagulating ability of the snow mass. When dust particles interact with ice chips or dense snow particles, the effect of freezing of solid dust with a coagulant through a liquid (water) cuff occurs. If a massive dust particle has a high speed, it "melts" the channel inside the ice crumbs, getting stuck inside the ice. Such winding channels formed on the surface and in the depths of particles of snow or snow-ice mass from shock interaction with dust particles, further enhance the coagulating ability of the proposed coagulant. The snow mass, saturated with particles of captured dust, intensively falls out of the dusty stream of gases, which increases the efficiency of dust collection of the proposed method of gas purification. The resulting snow and dust sludge is removed from the cyclone dust collector by conventional hydraulic washing, without creating technical difficulties for the subsequent disposal (recycling) of sludge. The advantage of the invention is the possibility of utilizing snow mass removed from the territory of settlements in the winter, for which there is a need to clean the flue gases from dust during the heating period.

The method of cleaning gases from dust is effectively carried out if the amount of snow mass, ice crumbs or mixtures thereof is 0.1-10.0 kg / m ^{3 of} the gas to be cleaned. If the amount of snow mass, ice crumbs or their mixtures is less than 0.1 kg / m ³ , the concentration of coagulant in the working space of the cyclone will be insufficient and the dust collection efficiency will be close to the level of the prototype. If the amount of snow mass, ice crumbs or their mixtures is more than 10.0 kg / m ³ , then the cost of spraying snow mass increases significantly. If the dust content of the gas to be purified increases, then the flow rate of snow mass, ice crumbs or their mixtures must be increased by 0.5-1.0 kg / m ^{3 of} gas to be purified with an increase in gas dust content for every 0.2 g / m ³ .

Thus, due to distinctive features from the prototype, the claimed method acquires new properties: high coagulating ability of snow and snow-ice mass, ice crumbs; capture of dust particles by the surface and volume of snow particles; enhancing the effect of capillary wetting of particles; the occurrence of freezing of dust particles and snow-ice mass; modification (formation of channels, pores) of the bulk structure of snow particles during the interaction of snow with dust; the possibility of rational utilization of the snow cover of settlements in the winter; increasing the efficiency of dust collection of a gas purification method.

A method of cleaning gases from dust is implemented using the device shown in the drawing. It contains a steam generator 1 with a furnace 2, in which dusty flue gases are formed. The flue gases are concentrated in the chimney 3 of the steam generator. The flue gases are cleaned of dust in the cyclone 4. The cyclone contains an inlet pipe 5, a housing 6, an exhaust pipe 7, a dust collector 8, a dust water wash system 9. For supplying a snow coagulant to the cyclone, an inkjet apparatus 10 is installed on the housing, the nozzle nozzle 11 is located on its axis auxiliary gas. The inkjet apparatus is equipped with a loading hopper 12, in which a drum feeder 13 is installed. The supply of snow coagulant to the hopper of the jet apparatus is carried out by a screw batcher 14 having a loading box 15.

The method of cleaning gases from dust is as follows. In boiler unit 1, solid fuel is burned. In the furnace 2, flue gases dusted with ash, slag and unburned fuel are formed, which are sent to the collection chimney 3. They are cleaned in a cyclone 4. For this, dusty gases are fed through a tangentially installed pipe 5 into a cylindrical body 6, where dust is separated from the gas behind account of the action of centrifugal forces. The purified gas is removed into the atmosphere through the exhaust pipe 7. The dust enters the cyclone body into the dust collector 8 and is removed by the hydraulic wash system 9. An increase in the dust collection efficiency in the cyclone is achieved by irrigating the cyclone working space with snow mass or ice crumbs or snow-ice mixtures. To do this, a jet apparatus 10 is installed tangentially and tangentially to the dusty stream in the upper part of the cyclone body. Compressed or high-pressure fan air is used as auxiliary gas supplied through the nozzle pipe 11. Snow coagulant from the loading box 15 is fed by a screw batcher 14 into the hopper 12 of the jet apparatus 10, where large pieces of snow, ice are crushed with the help of a drum feeder 13 and dosed loading of crushed snow coagulant into the housing of the jet apparatus 10. The snow coagulant sprayed by compressed air intensively coagulates the dust in the housing 6 of the cyclone 4 and falls into the dust collector 8 of the cyclone in the form of snow-dust slurry and is removed by the hydraulic wash system 9 for disposal.

Experimental development of a method for cleaning gases from dust was carried out on a flaming laboratory boiler according to the proposed technical scheme. The fuel used was steam coal from the Yerunakovskoye deposit with a flow rate of 20 kg / h. Snow coagulant was sprayed with compressed air at a pressure of 0.2 MPa and a flow rate of 0.6 m ³ / min. Measurement of dust content of flue gases in the smoke path was carried out using the method of external filtration. The dust collection efficiency was calculated by a known method. In experiments, the optimum amount of snow coagulant was worked out depending on the dust content of the flue gases. The experimental data are presented in the table.

Table No. p. Coagulant consumption, kg / m ^{3 of} gas to be purified Dust collection efficiency,% 1 0.1 63.6 2 5,0 71.1 3 10.0 77.4 Prototype Data 4 - 60.0

It was found that the objective of the invention is achieved with a flow of snow mass in the amount of 0.1-10.0 kg / m ^{3 of} purified gas, and with an increase in dust content of the purified gas for every 0.2 g / m ^{3, the} flow of snow mass must be increased by 0.5 -1.0 kg / m ^{3 of} purified gas. These parameters can improve the efficiency of gas purification by 6-29% (rel.).

Claims (1)

A method for cleaning gases from dust, including introducing a gas to be cleaned into a cyclone with an upper axial exhaust pipe, purifying gas from dust due to the action of centrifugal forces during the translational movement of a rotating stream from top to bottom with a turn of the purified stream upward, supplying a humidified auxiliary gas stream to the cyclone, a stream of pressurized gas is introduced solid coagulant, wherein the coagulant is used as the natural snow mass or the crushed ice or a mixture thereof in an amount of 0.1-10.0 kg / m ³ of gas to be purified, and grown with ohm dusty gas to be cleaned for every 0.2 g / m ³ of their flow is increased by 0.5-1.0 kg / m ³ of gas to be purified.