RU2166980C2 - Mass-transfer plant - Google Patents

Abstract

FIELD: chemical water treatment at thermal power stations and boiler; chemical engineering, manufacture of sulfuric acid. SUBSTANCE: mass-transfer plant consists of 1st stage and 2nd stage apparatus. First stage is centrifugal vortex mass exchanger. Second stage of plant is made in form of reservoir with unit ensuring contact of liquid medium with gaseous medium. Innovation of invention consists in availability of shell (length of pipe) mounted inside housing on its lower cover and branch pipe feeding medium to second-stage reservoir; both stages are connected in liquid and gas flows by means of pipes; reservoir of device is provided with liquid dispersing unit. EFFECT: improved quality of desorption of gases from liquid or adsorption of definite gases by liquid from common gas flow. 7 cl, 2 dwg

Description

 The invention relates to the field of power engineering and can be used in chemical water treatment systems at thermal power plants and boiler houses as a decarbonizer. In addition, the invention relates to chemical technology and can be used as an absorber, for example, in the production of sulfuric acid and as a stripper.

 Mass transfer apparatuses are known and are widely used, which are a column filled with Raschig rings, in which liquid is contacted in countercurrent and gas / liquid is supplied from above and gases from below /. "Processes and Apparatuses of Chemical Technology", publishing house "Chemistry", Moscow, 1963, p. 599, Fig. 17-6, L. 2. Handbook of an energy chemist edited by V. Golubtsov et al. State Energy Publishing House, Moscow, Leningrad, 1958, Volume Two, pp. 156, 157, FIG. 9-11, 9-12, decarbonizers.

 The disadvantage of these devices is their bulkiness, high metal and material consumption.

 They are less bulky and have significantly lower metal and material consumption of the apparatus without aggregate / Rashig rings /, especially centrifugal-vortex devices. For example, a degassing installation protected by the USSR copyright certificate N 1402582, cl. C 02 F 1/20. It is small-sized, has a low metal consumption.

 However, in this installation there is no forced air supply, and the ejection capacity of the water was insufficient / an order of magnitude lower than the norm N: cubic meters. m air per ton of water. But even so, the decrease in carbon dioxide in water was up to 6 mg / l at a rate of 4 mg / l, but this was not enough.

 As a prototype of the entire installation, a degassing installation protected by the USSR copyright certificate N 1402582, class. C 02 F 1/20, containing as a first stage a centrifugal vortex mass exchanger, as a second stage - a contact device in the form of an ejector connected to a container.

 The known centrifugal vortex-type mass exchanger, selected as a prototype, has a cylindrical body with upper and lower end caps having central holes, a centrifugal contact device (cyclone) made in the form of a shell of a larger diameter, covering the lower part of the body, liquid inlet and outlet pipes and gaseous media (the inlet pipe of the liquid medium is connected tangentially to the upper part of the housing, the inlet pipe of the gaseous medium to the cyclone, the outlet pipe of the liquid medium - to the cyclone, and the outlet pipe of the gaseous medium to the upper housing cover).

 A prototype (centrifugal-vortex-type mass exchanger) was manufactured and tested as a decarbonizer for a productivity of 450 t / h. Tests showed a number of shortcomings. The calculated quality of carbon dioxide removal (desorption) has not been achieved. The reason was that on the bottom cover with a central hole there was no rim around the hole. The water flow had a helical motion from top to bottom, while the vertical component of the velocity (due to gravity) was no less than the horizontal. As a result, not all water got into the holes and was broken into jets. Up to half the amount of water merged into the opening of the lower cover, almost without dispersion and poorly in contact with the air stream.

 Drops of moisture were carried through a pipe with a stream of exhaust air, which could lead to icing up of the apparatus in winter.

 The disadvantage is also the large diameter of the casing in which the water is swirling, while for a small diameter the gas throughput is insufficient. (With a diameter of 1 meter, the circumference is 3.14 m. With such a long path, the water loses its kinetic energy and speed and increases the vertical component of the water velocity).

 The aim of the invention is to eliminate the disadvantages of the prototype, namely: to improve the quality of desorption and absorption of gases and the creation of an installation that allows a method of mass transfer between a liquid and gas, namely to improve the quality of desorption of gases from a liquid or absorption of certain gases by a liquid (for example, during decarbonization of water or absorption sulfur compounds from the gas stream in the production of sulfuric acid), minimizing drip entrainment of liquids without installing an additional droplet eliminator, reducing loss of speed water while spinning water to use this speed to better contact media.

 This goal is achieved by the fact that in the known mass transfer apparatus of a centrifugal vortex type containing a cylindrical (or composed of two cylinders of different diameters) body with upper and lower end caps having central holes (caps in the form of washers), a centrifugal contact device (cyclone) made in the form of a shell of a larger diameter, covering the lower part of the body, inlet and outlet pipes of liquid and gaseous media, of which at least the supply pipes (pipe) of the liquid medium dsoedineny tangentially housing to the bottom cap is attached along the edge of the hole shroud diameter smaller than the body diameter (pipe section) forming a threshold that prevents drainage of water through the hole in the lid. Moreover, the specified device is only the first stage of installation. In addition, the proposed installation has an apparatus used as a second stage of media contact, made in the form of a vertical round-shaped container (cylindrical) with free discharge of liquid into another container (or a container with an adjustable level), in the upper part of which there is a device for dispersing liquid ( for example, made in the form of a perforated pipe or a pipe with slots connected to a pipe that discharges liquid from the first stage of the installation). If necessary, a hole plate (another dispersing device) may be placed below this dispersing device.

 This tank has a gaseous medium supply pipe and a gaseous medium removal pipe connected to a gaseous medium supply pipe of the apparatus of the first installation stage. The second stage of the installation is the only one, and the devices of the first stage can be several (one, two, three or four).

 In FIG. 1 shows the proposed mass transfer installation, a longitudinal section.

 In FIG. 2 - a variant of the first installation stage (centrifugal vortex mass exchanger).

 The mass-exchange installation contains two apparatuses connected in series: a centrifugal-vortex mass exchanger (the first stage of the installation, which may be several, connected in parallel), consisting of parts 1-13, and a drip-jet mass exchanger, consisting of parts 14-21. The first stage of the installation (centrifugal vortex mass exchanger) contains a cylindrical housing 1 (or a housing composed of two cylindrical shells of different diameters) with upper 2 and lower 3 end caps having central openings, a pipe 4 for exhausting the gaseous medium, threshold 5 (shell , pipe segment), tangential pipe 6 (there can be two or more), holes 7 in the lower part of the body (holes can be of circular cross section, in the form of longitudinal slots or in the form of short tangential pipes 7a, centrob a hedgehog contact device (cyclone) having a shell 8 larger than the diameter of the housing, into which the lower part of the housing 1, the upper cover 9, the lower cover 10, the pipe for supplying a gaseous medium 11, which is a pipe section passed through the lower cover 10, are lowered the formation of the bead, and connected by a pipe 21 to the apparatus of the second stage, a branch pipe for discharging a liquid medium 12, connected to the housing tangentially (it is possible to connect the pipe 12 to the bottom cover 10a, if it is conical, and if the gaseous medium is supplied n by a pipe 21 connected tangentially to the shell 8, see the variant in FIG. 2) washer 13.

 The second stage of the installation contains a vertical cylindrical free discharge tank 14 (or a container with an adjustable liquid layer in the lower part), in the upper part of which there is a dispersing device 15, made in the form of a perforated pipe or pipe with slots, connected to the outlet pipe 12 of the apparatus of the first stage, the second dispersing device 16, made in the form of a plate with holes and with a side 17. A pipe 18 for supplying a gaseous medium is attached to the lower part of the tank 14 (tangentially to provide atelnoe movement of the gaseous medium within the container 14), and pipe 19 for returning a liquid in the storage tank (not shown) after its contact with the gases. In the upper part of the tank 14 there is a central pipe 20 for discharging the spent gaseous medium, to which pipes 21 are connected for supplying the gaseous medium from the second stage of the installation to the first. Pipes 21 connecting in a gaseous medium the second stage of the installation with all the devices of the first stage can be connected tangentially to the pipe 20 in order to better use the rotational energy of the gaseous medium.

 We consider the operation of the mass transfer installation first when using it as a stripper (water decarbonizer).

 Water saturated with carbon dioxide obtained by softening it in hydrogen cation-exchange filters is fed into the housing 1 through the tangential pipe 6 and the water acquires a rotational movement, due to which free carbon dioxide is separated by centrifugal forces and carried away by the air stream (through pipe 4). Next, water, coming in contact with air and moving downward in a spiral, overcomes the washer 13 (the installation of the washer is optional, however, it creates a certain thickness of the rotating layer of liquid) and enters the annular space between casing 1 and the shell 5 and further through the holes 7 or through short tangential connections 7a (see FIG 2..) enters the annular space between the housing 1 and the shroud 8 (misses the centrifugal contact device - cyclone). When passing through holes 7 (nozzles 7a), the water is crushed into separate jets and droplets (dispersed) and ejects air. Intensive contact of water with air occurs. Next, the water, preserving the rotational motion, is pressed against the wall 8 and is separated from the air. There is a separation. The separated air is returned to the housing 1 through the shell 5 together with the air coming from the pipe 21. The partially decarbonized water, which maintains the dynamic pressure of the rotational movement, is supplied through the pipe 12 to the second stage of the installation - to the dispersing device 15 and is sprayed inside the container 14 in contact with a rotating stream of air. Next, the water flows down the walls into the plate 16 and is once again dispersed and in contact with a rotating stream of air. The water finally freed from carbon dioxide flows through the pipe 19 into the storage tank or is supplied directly to the consumer if a certain water level is held in the lower part of the tank 14. Air from the blower fan is supplied to the mass transfer unit through the tangential pipe 18 and acquires a rotational movement inside the container 14, in contact with the streams of dispersed water before and after the plate 16. (The gaseous medium can be sucked off by the suction fan if it is connected to the pipe 4). Further, partially exhaust air is supplied through the pipe 20, through pipes 21 to one or several centrifugal-vortex mass exchangers (in the first stage of installation) and is in contact with water (described above). Depending on the performance, one, two, three or four devices of the first stage are included in the work. For example, the productivity of one unit of the first stage is 120 t / h, and the entire installation is up to 480 t / h. With a load of 200 t / h, you can turn on two devices. On each device, locking devices for liquid and gas are installed.

 The operation of the installation as absorption is similar to that of desorption. For example, in the production of sulfuric acid, sulfuric acid is supplied to the tangential nozzles 6, and gases are injected into the nozzle 18 (or, if there is a suction fan connected to the nozzle 4) instead of a blower, gases containing sulfur compounds. With repeated contact of sulfuric acid with gases, sulfuric gases are absorbed by acid. The concentration of sulfuric acid increases.

 The connection of the supply pipe of the gaseous medium to the container and the connection of the container with a gas duct (pipe) with the pipe for supplying the gaseous medium of the centrifugal vortex apparatus of the first stage make it possible to use a blower or suction fan to supply a gaseous medium and to carry out a deeper mass transfer between the liquid and gas (to carry out desorption or absorption) by increasing the amount of gaseous medium and the organization of a two-stage process of mass transfer.

 The presence of one or more dispersing plates inside the tank allows for a deeper mass transfer process between the liquid and the gases (gas desorption or absorption).

 The presence of several, connected in parallel, centrifugal-vortex devices of the first stage and the connection of each of them with a gas duct and a liquid pipe with a second-stage device allow achieving a wide range of load regulation (increasing the depth of load regulation) from 5 to 100 percent.

 The presence of a threshold (pipe section, shell) with a diameter equal to the diameter of the hole in the bottom cover of the centrifugal vortex apparatus body and located inside the body, allows you to direct the entire fluid flow through the holes or tangential nozzles and subject it to dispersion and cause this fluid flow to eject a gaseous medium and intensively carry out contact and mass transfer between them.

 The passage of the gaseous medium supply pipe (from the second stage apparatus to the first apparatus) through the lower cover of the centrifugal contact device and its installation with a gap from the lower housing cover (from the lower edge of the shell forming the threshold), allows to reduce and minimize droplet entrainment of gaseous liquid Wednesday. (For example, in the embodiment of the apparatus of Fig. 2 this ablation will be greater, since all the jets of liquid will intersect the intense gas stream, and in the embodiment of Fig. 1 a small gas stream).

 The execution of the second stage of the installation in the form of a vertical tank, the tangentially connecting the gaseous medium inlet pipe and the presence of the gaseous medium outlet pipe in the center of the upper cover allow this apparatus to work like a cyclone, i.e. to separate the liquid to the periphery, and to release the gaseous medium from moisture drops, which significantly reduces the entrainment of moisture from the installation and will allow you to do without special drop eliminators.

Claims (7)

 1. Mass-transfer installation having two stages of mass-exchangers connected in series, the first stage includes a centrifugal-vortex-type apparatus containing a cylindrical body having openings or tangential nozzles in the lower part, with upper and lower end caps having central openings, inlet and outlet nozzles liquid and gaseous media, of which the inlet pipes of the liquid medium are connected tangentially to the housing of the first stage, the second stage includes an apparatus, which is a free discharge or storage tank in which a liquid dispersing device is placed, to which a pipe for discharging a liquid medium from a first-stage apparatus is connected, characterized in that a pipe for supplying a gaseous medium is connected to a container of a second stage and this container is connected by a pipe or duct to a gaseous supply port the medium of the centrifugal-vortex-type apparatus of the first stage, while the lower part of the housing of the centrifugal-vortex-type apparatus of the first stage is covered by a larger diameter shell with the upper th and lower lids.  2. Mass transfer apparatus according to claim 1, characterized in that at least one more dispersing device in the form of a perforated plate is located inside the second stage vessel below the dispersing device, made in the form of a perforated pipe or a pipe with slots.  3. Mass transfer installation according to claim 1, characterized in that the container with dispersing devices, which is the second stage of the mass transfer installation, is connected through the gaseous and liquid media flows with several centrifugal-vortex type devices installed in parallel, which are the first stage of the mass transfer installation.  4. The mass transfer installation according to claim 1, characterized in that a shell with a diameter smaller than the diameter of the housing is attached to the bottom cover of the centrifugal-vortex type apparatus body along the edge of the hole, forming a threshold that prevents water from draining through the opening in the bottom cover.  5. Mass-transfer installation according to claims 1 and 4, characterized in that the pipe for supplying a gaseous medium is passed inside the centrifugal contact device and is installed with a gap between the bottom cover of the housing.  6. The mass transfer apparatus according to claim 1, characterized in that the container body is made in the form of a vertical cylinder with upper and lower end caps, the gaseous medium supply pipe is connected tangentially to the container body, and a gas outlet pipe is connected in the center of the upper container cover.  7. Mass transfer installation according to claim 1, characterized in that the casing of the centrifugal vortex apparatus is made up of two cylinders.

Images