EA039146B1 - Method for wet gas purification and device for its implementation - Google Patents

Abstract

The invention relates to wet gas purification and can be used in power industry, metallurgy and chemical production. A device for wet gas purification comprises a cylindrical casing (1), a gas supply pipe (17) with a flushing device (20) and flushing nozzles (19), a gas outlet pipe (13) and a drain pipe (18). The casing contains rotary table liquid feeders (2 and 9), vane swirlers (3 and 10), their twist being opposite to the inlet pipe, placed in annular slots. Outer ends of the vane swirlers are raised above their inner ends. Above the vane swirlers (3 and 10), annular inserts (14 and 16) are mounted; they can be removed or shifted to vary the area of the slot. The feeders (2 and 9) of the irrigation liquid are made with a double bottom, and the irrigation liquid supply pipes (4 and 11) are equipped with units for supplying chemical reagents (5 and 12). Between the vane swirlers (3 and 10) which are installed one above the other, a constriction device (6) is inserted which forms an annular channel (7) with the casing wall or with a special annular expansion of the casing (8), the annular channel being provided with a drain pipe (15). To carry out wet cleaning and separate disposal of the trapped pollutants, the gases swirled by the tangential pipe (17) are passed through two annular swirlers (3 and 10) over which the liquid with chemical reagents supplied in countercurrent is emulsified, and interact with the reagents. The slurry downstream of the lower swirler (3) is removed from the gas cleaner through a branch pipe (18), and the slurry downwards of the upper one (10) is drained into the annular channel (7), from where it is removed from the gas cleaner through the drain pipe (15). Separate cleaning of gases from harmful inclusions and their separate utilization are provided.

Description

The invention relates to wet cleaning of gases from solid, liquid and gaseous toxic inclusions and can be used in energy, metallurgy, chemical production and other industries.

In non-ferrous metallurgy and chemical technology, a method is known for cleaning gases from ash and sulfur oxides, which consists in bubbling contaminated gas through a layer of liquid. Cleaning is carried out in foam apparatus with overflow and failure plates (Handbook of dust and ash collection. Edited by A.A. Rusanov, M., Energoatomizdat, 1983, p. 94-104).

The method is characterized by a relatively low degree of gas purification from fine dust fractions due to the formation of large gas bubbles during bubbling, passing at high speed through the liquid layer. As a result, fine dust particles do not have time to separate to the phase interface during the passage of the foam layer, and gaseous components (sulfur oxides) do not react with reagents in the liquid phase.

A known method of wet scrubbing of gases, including the supply of a gas stream into the cylindrical body of the gas cleaner, the interaction of the gas stream with the supplied countercurrent liquid when passing through the annular slot in a wide range of speeds.

The method is implemented in a device for wet cleaning of gases, containing a cylindrical body, pipes for supplying and discharging gases, located coaxially with the body above the gas supply pipe with the formation of an annular gap with respect to the wall of the body, a dosing liquid dispenser with a pipe placed above it for supplying an irrigating liquid, annular blade swirler (AS USSR No. 1212515, class B 01 D 47/04, 1986).

The disadvantage of the method and apparatus is insufficiently high productivity, which is confirmed by the low gas velocity at the exit from the working space (foam layer), i.e. in the full section of the apparatus, which is 2.0-2.5 m/s, the instability of the foam layer and the low degree of gas purification.

Closest to the proposed invention is a method of wet cleaning of gases and a device for its implementation (RF patent No. 2635626).

The method includes supplying a gas flow to the gas cleaner housing in a swirled tangential branch pipe, supplying a gas flow through an annular slot in a swirling form, interaction of the swirling gas flow with a countercurrent supplied liquid in a wide range of speeds and emulsification, swirling the gas flow in the annular slot in the opposite direction, acceleration /deceleration of the gas flow in the annular slot by overlapping/opening part of the slot area adjacent to the inner perimeter of the slot.

The method is implemented in a device containing a cylindrical body, pipes for supplying and discharging gases, a pipe for supplying irrigating liquid, a poppet dispenser of irrigating liquid, a vane swirler placed in the annular slot, having a swirl direction opposite to the swirl of the gas to be purified by the tangential inlet, the outer ends of the trailing edges of the blades the swirlers are raised above the internal ones adjacent to the poppet dispenser of the liquid, to a height whose ratio to the width of the annular gap lies in the range of 0.2-3.7; equipped with a float and a valve associated with it for closing-opening the impulse pipe connected to the pipeline, the gas cleaner body is made in the form of a regular prism with at least four side faces, and the irrigating liquid poppet dispenser is made in the form of a polygon, similar to the base of the prism, above the blade h an annular slot is installed with a swirler in the annular slot, covering a part of the slot area adjacent to the inner perimeter of the slot, with the possibility of removal or movement in the axial and / or radial direction to change the area covered by the annular slot, the irrigating liquid poppet dispenser is made with a double bottom, and at the inlet pipes for supplying irrigating liquid, at least one unit for supplying chemicals is installed.

One of the main disadvantages of the method and device is the inability to separately remove the trapped dust and products of chemical reactions from the gas cleaner.

The present invention is directed to a method and device in which the gas is passed sequentially through at least two annular slots with vaned swirlers, where it emulsifies liquids that are fed to the vaned swirlers in the annular slots and are removed after them separately.

The problem is solved due to the fact that the gases are sequentially passed through two annular slots with paddle swirlers, which are separately supplied with irrigating liquids and, after passing through the emulsion layers, are separately removed from the gas cleaner. To do this, two blade swirlers are installed one above the other in the annular gap in the gas cleaner housing, each of which is equipped with pipes for supplying irrigating liquid, in front of which at least one chemical reagent supply unit is installed to neutralize harmful impurities in the gases being cleaned. A narrowing device is installed between the bladed swirlers, which forms an annular channel with the housing wall, equipped with at least one drain pipe for draining

- 1 039146 from the upper vane liquid swirler. The passage diameter of the constriction device must be less than the inner diameter of the upper annular slot, so that all the liquid after the upper swirler enters the annular channel and does not fall on the lower swirler. To do this, the upper part of the housing above the annular channel can be expanded. The size of the annular channel depends on the flow rate of the irrigating liquid supplied for irrigating the upper swirler. To prevent liquid overflow from the annular channel to the lower swirler, at high flow rates, the gas cleaner body can have a special annular expansion that increases the volume of the annular channel, as well as an inclination of the bottom of the annular channel towards the drain pipe. The cross section of the annular channel can be conical, cylindrical, etc.

The need for solving this problem can be explained by the example of cleaning flue gases from coal combustion. The proposed device will allow in the first layer of emulsion along the gas flow above the lower annular bladed swirler with high efficiency. to catch the ash and throw it into the dump with the ash pulp, and in the second (upper) layer of the emulsion from the gases cleaned from ash, using reagents in the irrigation liquid, extract sulfur oxides into the pulp and remove them from the gas cleaner separately from the ash. Depending on the chemical reagent used to neutralize sulfur oxides, direct the resulting pulp to the production of gypsum, sulfur, acid or fertilizers.

In the case of using lime milk for sulfur trapping, a multiple increase in the water consumption for irrigating the upper vane swirler is required in comparison with the fluid flow required for ash trapping in the lower emulsion layer above the vane swirler. This is due to the need to dissolve the amount of poorly soluble lime necessary to neutralize sulfur oxides and obtain lime water as a reagent. If the gas cleaner is intended only for cleaning flue gases from ash and sulfur oxides, and gypsum extraction is not provided, then the proposed device allows organizing the recirculation of the pulp after the upper vane swirler and dumping the reaction products into the ash dump with a low specific consumption of irrigating liquid. In this case, the liquid after the upper vane swirler can be drained into a circulation tank, from where it can be pumped, for example, into a hydrocyclone, from which the clarified large part returns to irrigate the upper vane swirler, and the smaller part of the liquid condensed in the hydrocyclone is sent to irrigate the lower vane swirler of the gas cleaner, after which it is removed to the dump. The flow of liquid to the dump is compensated by replenishing the circulation tank with milk of lime. As a result of the organization of liquid recirculation at the upper stage, the total water consumption for cleaning flue gases from ash and sulfur oxides remains low, and the degree of gas cleaning from ash and sulfur oxides increases.

A similar result can be achieved with two scrubbers installed in series with a single swirler, but in this case the cost of the scrubbers will be almost twice as expensive and require twice the area for the gas scrubber, which is usually not found in existing coal-fired power plants.

The invention is illustrated by drawings.

In FIG. 1 shows a device for wet gas cleaning with two vane swirlers and pipes for supplying irrigating liquid, with a conical constriction device installed above the lower vane swirler and forming an annular channel with a wall of the gas cleaner housing, equipped with a drain pipe.

In FIG. 2 - gas scrubber with an annular channel between the swirlers, formed by a cylindrical constriction device and a rectangular annular extension of the housing with a drain pipe.

The device for wet cleaning of gases (Fig. 1) contains a cylindrical body 1, a gas supply pipe 17 with a flushing device 20 and flush nozzles 19, a gas outlet pipe 13 and a drain pipe 18. In the body, two poppet-shaped liquid dispensers 2 and 9 are installed one above the other with bladed swirlers 3 and 10 placed in the annular slots with a swirl opposite to the inlet pipe 17. The outer ends of the swirler blades are raised above the inner ones. Above the bladed swirlers 3 and 10 in the annular slots there are annular inserts 14 and 16 with the possibility of removal or movement to change the area of the slot. Disc dispensers of irrigating liquid 2 and 9 are made with a double bottom, and irrigating liquid supply pipes 4 and 11 are equipped with units for supplying chemical reagents 5 and 12. . It forms with the housing wall an annular channel 7 for the draining liquid, which is equipped with a drain pipe 15. drain pipe 15. The proposed device works as follows: in the body 1 of the gas cleaner (Fig. 1 and 2) contaminated gas flows in a swirling flow through the tangential or chordal gas supply pipe 17. Then the gas passes through the lower bladed swirler 3 installed in the annular slot, where twists in the opposite direction. Irrigating liquid, in which, if necessary, the mixer 5 can be added chemical

- 2 039146 chemical reagent, through pipe 4 enters the poppet dispenser of the irrigating liquid 2, forming a bath, which is untwisted by the gas rotating above it and due to centrifugal forces begins to break off in the form of a film from the edges of the poppet dispenser 2 to the wall of the housing 1. Above the slot, the liquid meets with a swirling gas flow aligned due to a turn in the swirler and forms a stable, intensively rotating layer of a gas-liquid emulsion through which the gases entering the device are washed. Liquid with harmful impurities trapped in the lower layer of the gas-liquid emulsion flows down to the bottom of the housing and is removed from the gas cleaner through pipe 18. possible dust deposits. The gases purified in the lower emulsion layer pass through the constriction device 6 into the upper annular swirler 10. Here they meet with the flow of liquid mixed with the chemical reagent in the mixer 12, which flows through the pipe 11 to the poppet dispenser 9 and creates a rotating emulsion layer. After washing in this emulsion layer, the purified gases are removed from the gas cleaner through the outlet pipe 13, and the liquid with trapped harmful impurities flows into the annular channel 7 formed by the constriction device 6 and the housing or the expansion of the housing 8 (Fig. 2), and then through the drain pipe 15 removed from the gas cleaner. Annular liners 14 and 16, mounted above the annular bladed swirlers 3 and 10, allow you to change the flow area of the swirlers to optimize the operation of the scrubber in a wide range of gas flow rates.

The proposed method and device allow in one gas cleaner with two annular bladed swirlers and a narrowing device between them to separate the capture of dust and gaseous or two different gaseous impurities and their separate removal from the device for further disposal.

Thus, the above information shows that when using the claimed method and device, the following set of conditions is met:

a tool that embodies the claimed method and device in its implementation, is intended for use in industry, namely in energy, metallurgy, chemical production;

for the claimed group of inventions in the form as it is characterized in the independent claims of the stated claims, the possibility of its implementation using the means described in the application is confirmed.

Therefore, the claimed group of inventions meets the condition of industrial applicability.

Claims (2)

1. A device for wet cleaning of gases, containing a cylindrical body, inlet and outlet pipes with a flushing device with flushing nozzles in the inlet pipe, a pipe for supplying irrigating liquid, a poppet dispenser of irrigating liquid with a double bottom and a vane swirler in the annular slot, having a twist direction gases, opposite to swirling by a gas supply pipe, with blades, the outer ends of which are raised above the inner ones, with an annular insert above the bladed swirler in the annular slot, covering part of the slot area adjacent to the inner perimeter of the slot, with the possibility of removal or movement in the axial and / or radial direction to change the overlapping area of the annular gap, and at the inlet of the pipe for supplying the irrigating liquid, at least one unit for supplying chemical reagents is installed, characterized in that a narrowing device with an inner diameter, m with a smaller internal diameter of the upper annular slot with a vaned swirler, which forms an annular channel for the liquid draining from the upper vaned swirler with at least one drain pipe with the housing wall or housing extension. 2. The method of wet cleaning of gases using the device according to claim 1, including supplying a gas stream to the gas cleaner housing in a swirling tangential branch pipe, passing the gas stream through the annular slot, swirling the gas stream in the annular slot in the opposite direction, interacting the swirling gas stream with the supplied liquid counterflow and emulsification, acceleration/deceleration of the gas flow in the annular gap by closing/opening a part of the area of the gap adjacent to the inner perimeter of the gap, characterized in that in order to obtain suitable for further separate disposal of the reaction products carried out in the gas cleaner, the gas is passed sequentially, at least at least through two annular slots and a narrowing device installed between them, and emulsifies the liquids that are fed to the annular slots and removed after them separately.