Wet gas cleaning apparatus

Abstract

This utility model relates to contact mass-transfer and reaction apparatus and can be used, in particular, for wet gas cleaning of acids, organic solvents, solid particles, aerosols, and other contaminants. The technical result is the creation of a reliable wet cleaning apparatus.The device's efficiency is enhanced by its two-stage processing. The first stage includes two inlet nozzles, each containing a confuser, a throat, a diffuser, a straight section, and a spray system. The second stage comprises a cylindrical housing. The inlet nozzles are positioned tangentially relative to the cylindrical housing. Local flow accelerators, formed as separate plates, and an exhaust pipe are mounted on the end surface of the housing in the straight section area of ​​one inlet nozzle. A baffle plate is installed in the area of ​​the other inlet nozzle. A sludge water drain nozzle is fixed in the side wall of the housing. The proposed device increases the efficiency of wet gas cleaning in a counter-current flow system.

Description

[0001] Technical field

[0002] The utility model relates to contact mass-exchange and reaction apparatus and can be used, in particular, for wet cleaning of gases from acids, organic solvents, solid particles and aerosols, as well as other pollutants.

[0003] Technology Level

[0004] A design of a hollow spray absorber is known [see Dytnersky Yu.I. Processes and apparatuses of chemical engineering: Textbook for universities. 3rd ed. In 2 books: Part 2. Mass exchange processes and apparatuses. Moscow: Chemistry, 2002. - 368 p.: ill. T8VM 5-7245-1232-7 (Book 2)], which is a hollow column in which the gas moves from the bottom up, and the liquid is supplied through nozzles located in the upper part of the column with the direction of the spray torch usually from top to bottom. Hollow spray absorbers are distinguished by their simple design and low cost, they have low hydraulic resistance and can be used with heavily contaminated gases, although this causes difficulties with the operation of the nozzles.Disadvantages: low productivity, which is caused by gas mixing along the column height, difficulty in operating nozzle devices with high spray quality (clogging of their holes in the presence of solid inclusions in circuits with recirculation of the working fluid), uneven distribution of the gas flow, low quality of cleaning.

[0005] A known device is a packed absorber (RU Patent No. 2650930, 2017), comprising a housing with nozzles for dust-laden and purified gas, a sprinkler, support grates between which the packing is located, and a sludge removal device. The packing is made in the form of hollow balls with a helical groove cut into their spherical surface. The packing can be made of porous polymeric materials, glass, porous rubber, composite materials, wood, stainless steel, titanium alloys, and precious metals. The sprinkler is designed as a nozzle. Disadvantages of this device include relatively high hydraulic resistance due to the packing layer, clogging of the packing with solid inclusions, difficulty in cleaning it or the high cost in the case of regular packing, and the high cost of packing bodies that are stable in acidic environments and at high temperatures.

[0006] Various techniques are used to intensify the separation of liquid droplets from a gas flow, most commonly the creation of a centrifugal field. For example, a well-known design for a two-stage wet gas cleaning apparatus with a vortex chamber and a dip plate (patent RU 125880, 2013) comprises a vertical cylindrical body with a tangentially located nozzle at its bottom for swirling the gas-liquid flow, a perforated irrigation pipe located along the axis of the body, and a guide device adjacent to it on the outside for additional swirling of said flow. The apparatus is equipped with a second cleaning stage in the form of an additional compartment adjacent to its upper section with an independent supply of cleaning fluid, the lower section of which contains a perforated dip plate open into the apparatus body.Disadvantages: insufficient intensity of interaction between the absorbent and the gas flow due to the presence of two guide devices with different directions of flow, uneven distribution of the absorbent along the height of the irrigation pipe, since the liquid is supplied to it by creating a water seal in the lower part of the housing, and not directly.

[0007] The closest in technical essence is a multifunctional device with counter-swirling flows of processed gas (RU Patent No. 2,339,436, 2007), comprising a housing, lower and upper inlet pipes, an outlet pipe, and a liquid supply system. The device consists of two processing stages, where the first stage of the device includes upper and lower inlet pipes equipped with tangential swirl devices and centrifugal tangential nozzles, while the second stage includes a centrifugal mixing chamber with an inlet pipe equipped with a tangential swirl device, a diffuser, a confuser, a de-swirl device, and an outlet pipe. The device is essentially a wet cleaning device with counter-swirling flows and possesses all the advantages of counter-swirling flow devices (CSFD).In VZP units, special attention is paid to the design of the upper and lower gas-dust mixture inlets and the development of devices such as swirl traps, fairings, and baffle plates, the use of which increases flow loading. All these techniques accelerate the separation of the dispersed phase from the dispersion medium, but from a wet cleaning perspective, the cleaning efficiency is primarily determined by the wettability of the particles and their contact with the particles being captured from the flow. This is ensured by the correct nozzle type, spray angle, and installation location. In a multifunctional unit with counter-swirling gas flows, atomization is achieved by centrifugal nozzles installed inside the housing. The best humidification efficiency in the unit is achieved with a nozzle tilt angle of α relative to the horizontal. фequal to 30-40° and with a relative height of its location in the working chamber h / H=0.4-0.5. When capturing fine dust or absorbing impurities dissolved in the gas, this will not be sufficient for the effective operation of the device.

[0008] The problem that the claimed invention is aimed at solving is to ensure effective purification of gases from various impurities, including those dissolved in the gas.

[0009] Technical result - creation of a reliable wet cleaning apparatus.

[0010] Increasing the efficiency of the device during its use is achieved by the fact that the apparatus consists of two processing stages, wherein the first stage of the apparatus includes two inlet pipes 1 and 2, each of which contains a confuser 3, a neck 4, a diffuser 5, a straight section 6, an irrigation system 7, the second stage includes a cylindrical body 8, inlet pipes 1 and 2 are located tangentially relative to the cylindrical body 8, on the end surface of which, in the installation zone of the straight section 6 of one inlet pipe 1, local flow accelerators 9 are fixed, made in the form of separate plates, and an exhaust pipe 10, in the installation zone of the other inlet pipe 2 a baffle washer 11 is installed, in the side wall of the body 8 a pipe for draining sludge waters 12 is fixed.

[0011] The device is essentially a wet cleaning device with counter swirling flows and has all the advantages of counter swirling flow devices (CSFD).

[0012] The apparatus consists of two processing stages. The first stage of the apparatus includes two inlet pipes 1 and 2 for contaminated gas, located outside the housing 8 and tangentially relative to it. Each pipe contains a confuser 3, a throat 4, a diffuser 5, a straight section 6, and an irrigation system 7. A irrigation device consisting of a water supply pipeline and a nozzle is located in the confuser 3. Each pipe 1 and 2 is a Venturi tube, in which, according to Bernoulli's law, large droplets are broken into smaller ones by a turbulent gas flow, dust particles are captured by the water droplets, their subsequent coagulation, and subsequent sedimentation in the second stage. In this case, the Venturi tube functions only as a coagulator for highly efficient absorption of impurities dissolved in the gas by smaller droplets of absorbent before subsequent separation, so the speed in the throat can be reduced to 50÷100 m / s, which significantly reduces energy costs.The consumption of contaminated gas varies: one of the pipes (conditionally the left one) receives 2 / 3 of the total volume of incoming gases, the other (conditionally the right one) - 1 / 3.

[0013] Entering tangentially through two pipes 1 and 2 into the housing 8, the gas flow swirls. In the zone where the conventionally left flow enters the housing 8, local flow accelerators 9 are installed on its end surface. These accelerators form a stable rotating annular layer of dispersed particles, preventing their accumulation in the zone of maximum resistance to their movement and directing them toward the central zone of the housing 8. In this zone, the liquid particles are thrown toward the inner surface of the cylindrical housing 8. The flows rotate in the same direction. Upon meeting each other, the conventionally left flow experiences additional swirl, increasing the centrifugal forces acting on the particles, which enter through pipe 12 into the sludge water receiver 13.The gas, cleared of particles, rests against the conical top of the baffle washer 11, turns around and, having created a vortex paired with the main flow in the central part of the housing 8, moves towards the exhaust pipe 10 from the cylindrical housing 8.

[0014] The sludge receiver 13 is a gravity settling tank. As the sludge and solids settle, some of the absorbent can be returned to the apparatus as reflux through a closed-loop pressure circulation system consisting of a pipeline system 14, a mixing tank 15 with clean absorbent, and a pump 16.

[0015] The design is distinguished by its simple internal structure. Since wet cleaning processes use a highly corrosive medium—most often water—as the cleaning fluid, water becomes even more corrosive after contact with gases containing acidic flue gas components, particularly sulfur dioxide (SO2). The fewer internal components the device contains, the easier it will be to operate. The housing of the device (8) can be made of corrosion-resistant or chemically inert materials (depending on the operating temperature conditions).

[0016] The proposed device is shown in the drawing (Fig. 1 - general sectional view, Fig. 2 - sectional view of the dusty gas flow supply unit with guide inserts).

[0017] The device consists of two processing stages, wherein the first stage of the apparatus includes two inlet pipes 1 and 2, each of which contains a confuser 3, a neck 4, a diffuser 5, a straight section 6, an irrigation system 7, the second stage includes a cylindrical body 8, inlet pipes 1 and 2 are located tangentially relative to the cylindrical body 8, on the end surface of which, in the installation zone of the straight section 6 of one inlet pipe 1, local flow accelerators 9 are fixed, made in the form of separate plates, and an exhaust pipe 10, in the installation zone of the other inlet pipe 2 a baffle washer 11 is installed, in the side wall of the body 8 a pipe for draining sludge waters 12 is fixed.

[0018] The device operates as follows.

[0019] The contaminated gas flow is supplied to the device in two streams through the inlet pipes 1 and 2, and the flow rate of the contaminated gas is different: 2 / 3 of the total volume of incoming gases enters one of the pipes (conditionally left), and 1 / 3 enters the other (conditionally right). Each pipe contains a confuser 3, a throat 4, a diffuser 5, a straight section 6, and an irrigation system 7. The contaminated gas passes sequentially through the confuser 3, the throat 4 and the diffuser 5, and the straight section 6. The irrigation liquid enters the confuser 3 through the irrigation nozzle of the irrigation system 7. At the outlet of the nozzle, the liquid is broken up into droplets and the gas is wetting. In this case, the Venturi tube functions only as a coagulator for highly efficient absorption of impurities dissolved in the gas by smaller droplets of absorbent before subsequent separation, so the speeds in the throat can be up to 50÷100 m / s, which results in low energy consumption.

[0020] A high-flow stream (conventionally left) along with liquid droplets tangentially enters the internal volume of housing 8. Local flow accelerators 9 are mounted on the end surface of the housing, in the area where the inlet pipe is installed, to form a stable rotating annular layer of dispersed particles, preventing their accumulation in the zone of maximum resistance to their movement and directing them into the central zone of the housing. A second gas stream, containing finely divided liquid droplets, also swirls within housing 8 due to the tangential inlet. The streams rotate in the same direction. Upon encountering each other, the conventionally left stream experiences additional swirl, increasing the centrifugal forces acting on the particles, which pass through baffle plate 11 and enter sludge water receiver 13 through pipe 12.The gas, cleared of particles, rests against the conical top of the baffle washer 11, turns around and, having created a vortex paired with the main flow in the central part of the housing 8, moves towards the exhaust pipe 10 from the cylindrical housing 8.

[0021] The sludge receiver 13 is a gravity settling tank. As the sludge and solids settle, some of the absorbent can be returned to the apparatus as reflux through a closed-loop pressure circulation system consisting of a pipeline system 14, a mixing tank 15 with clean absorbent, and a pump 16.

[0022] Positive effect - the proposed device ensures an increase in the efficiency of the wet gas cleaning process in a counter-flow apparatus.

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