RU2095125C1 - Heat-and-mass exchanger - Google Patents

Abstract

FIELD: heat-and-mass exchangers. SUBSTANCE: heat exchanger relates to heat power engineering used as decarbonizer (desorber of carbon dioxide from water) in the system of water chemical treatment at thermal power stations and boiler houses as utilizer of heat of flue gases (economizer of contact pipe) and as contact steam water heater; additionally, heat-and-mass exchanger is used in the field of chemical technology as absorber and desorber, for instance, in production of sulfuric acid and in other chemical production processes. Exchanger has vertical cylindrical vessel with hole in upper cover where control centrifugal device is partially lowered. It is a shell with upper and lower end covers with tangential inlet of liquid and holes in shell lower part, and gas branch pipe in center of upper cover. Novelty of heat-and-mass exchanger is availability of hole in lower cover of contact centrifugal device. EFFECT: higher specific productivity of apparatus due to reduced aerodynamic resistance and its extended function application. 6 cl, 2 dwg

Description

 The invention relates to a power system and can be used in chemical water treatment systems at thermal power plants and boiler houses as a decarbonizer, thermal deaerator, contact vapor cooler in deaeration plants, as a contact water economizer for recovering heat from the exhaust gases of boilers and furnaces. 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 and heat transfer devices are known and widely used. They 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 /.

 These are absorbers and strippers / see L.I. A.N. Planovsky, V.M. Ramm, S.E. Kagan "Processes and Apparatuses of Chemical Technology", publishing house "Chemistry", Moscow, 1963, p. 59E, 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, p. 156, 157, FIG. 9-11, 9-12 decarbonisers. Contact economizer see L.Z.E.F. Pantyusheva, E.B. Stolper "Adjustment of gas-fired boilers, p. 32, Fig. 3, Nedra Publishing House, Leningrad, 1974.

 These are contact water heaters / see L. 4. E.P. Sosnin "Contact Water Heaters", Moscow, Stroyizdat, 1974, p. 250, Fig. 105 /.

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

 This disadvantage is eliminated in devices without a filler / without Rashig rings /. Such is the apparatus described in L. 5 "Mass transfer apparatus", ed. St. USSR N 186975, class B 01 D 53/18 and in [1] This apparatus is selected as a prototype.

 The known heat and mass exchanger, selected as a prototype, has a housing with inlet and outlet pipes of liquid and vase-like media, made of coaxially arranged shells of various diameters. The upper shell of a smaller diameter has an upper and lower cover, and the lower cover is solid, and the upper has a neutral hole with an inlet of a gaseous medium. In the upper part of the shell, a nozzle for supplying a liquid medium is tangentially connected, and in the lower part there are tangential nozzles. This shell is a centrifugal contact device, placed with the lower part / of the tangential nozzles / inside the larger shell, this larger shell can be described as a container, closed on top and having a number of devices / devices / to ensure multiple contact of liquid and gaseous media. This tank has outlet pipes for liquid and gaseous media.

 Heat and mass transfer in this apparatus occurs by contacting liquid and gaseous media with their parallel movement inside the upper shell and with multiple intersections of the media after leaving this shell.

 However, the selected prototype has some drawbacks, in particular, a sufficiently high aerodynamic drag for a gaseous medium, caused by insufficient flow capacity for the gaseous medium of the lower tangential nozzles of the centrifugal contact device / liquid and gaseous medium pass through these nozzles simultaneously, by multiple intersections of the media and numerous changes in the direction of movement wednesday For this reason, it is difficult to use the prototype as a contact economizer, wait for a contact water heater. The furnace geys in the furnaces and furnaces are formed in large quantities and are sucked off by low-pressure smoke exhausters.

 The aim of the invention is to remedy these disadvantages, namely reducing aerodynamic drag, increasing the throughput of the apparatus in a gas environment / increasing specific productivity /, simplifying the design, expanding the range of functional use of the apparatus.

 This goal is achieved by the fact that in a known heat and mass exchanger containing a housing with inlet and outlet nozzles of liquid and gaseous media, made in the form of a cylindrical vertical tank with a top cover having a central opening through which is partially lowered inward, with a gap from the bottom, a centrifugal contact device made in the form of a shell about the lower and upper end caps, the last of which has a central hole with a pipe of the gas medium, and to the upper part of the side wall of the shell the nozzles / nozzle / fluid supply are connected in angularly, in the lower part of the shell located inside the container, there are holes connecting it to the space of the container, characterized in that in the lower end cover of the centrifugal contact device there is a central hole connecting the centrifugal contact device with the internal space capacity, and the pipe of the gaseous medium is connected to the wall of the container above the holes in the centrifugal contact device.

 There are additional differences that contribute to the achievement of the goal. The gaseous medium nozzle is connected tangentially to the wall of the outer container and is the inlet of the gaseous medium, and the outlet nozzle of the gaseous medium is connected to the top cover of the centrifugal contact device. In the annular space between the walls of the tank and the centrifugal contact device below the gas medium nozzle and above the holes in the centrifugal contact device there is an annular partition / washer / that overlaps part of the annular space, this partition can be made equal to the cross section of this annular space i.e. completely overlapping it, if the heat and mass exchanger will be used as a contact steam-water heater.

 The holes in the lower part of the wall of the contact device are made in the form of horizontal slots.

 The centrifugal contact device is made of two shells / pipes / of different diameters, connected to each other in series, and the shell / pipe / of a larger diameter is located on top.

 In FIG. 1 shows the proposed heat exchanger, a longitudinal section; in FIG. 2 shows a variant of a heat exchanger that can only be used as a contact steam-water heater.

 The heat and mass exchanger comprises a housing consisting of a tank 1 made of a cylindrical shell with a bottom 2, an upper cover 3, a centrifugal contact device made of two shells / pipes / 4 and 4a / in FIG. 2 - on one shell 4 /, joined together by a ring / washer / 5. This device has a top cover 6 and a bottom cover 7 with central holes. Attached to the top cover / to the hole / pipe 9 of the gas medium. The centrifugal contact device has tangentially connected nozzles 9 / nozzle / fluid supply in the upper part, and holes 10 made in the form of horizontal slots in the lower part. In the annular space between the wall of the tank 1 and the shell 4A there is an annular partition / washer / 12, which reduces this annular space. In the upper part of the cylindrical tank 1, a gaseous medium 11 pipe is tangentially or radially connected. In the lower part of the tank 1 there is a tangential pipe 15 for discharging the contacted liquid. The number 14 denotes a vertical rotating fluid level / media interface /. 15 additional holes in the casing 4 in the embodiment of the heat and mass exchanger shown in FIG. 2.

 Let us consider the operation of a heat and mass exchanger first when using it as a decarbonizer / stripper, which extracts free carbon dioxide from water using air /. See FIG. one.

 The carbon dioxide-containing water is fed through the nozzles 3. Due to the tangential supply, the water acquires a rotational movement inside the shells 4.4a, forming an annular interface. According to the law of conservation of angular momentum, the water pressure decreases with decreasing spin radius / from the periphery to the center /, and the water rotation speed increases. Better twist contributes to the increased diameter of the shell 4 in comparison with the shell 4a. The highest speed of rotation of water at the interface / 14 /. The movement of water is spiraling from top to bottom. In the lower part of the centrifugal contact device, water meets holes 10 in its way. The thickness of the rotating layer of water is determined by the width of the ring of the washer 7 and the section of the holes 10. When the water moves from the center to the periphery / to the wall 4a / its rotation speed decreases, and the pressure increases. Most of the water passes through the holes 10, and part through the edge of the washer 7. Or 100% of the water passes through the holes 10 / depending on the cross section of the holes and on the diameter of the hole on the washer 7 /. From the holes 10, water enters the annular space of the container 1. Due to the horizontal arrangement of the slots 10, the direction of water movement along the tangent to the shell 4a. Water is divided into small jets and drops, breaking the annular space of the tank 1, the water continues to rotate / due to the tangential component of the movement / along the wall of the tank. Then it enters the outlet pipe 13. The air participating in the process of decarbonization of water is blown by the blower fan into the tangential pipe 11. If you attach a suction fan to the pipe 8, then air will flow through the pipe 11 due to vacuum. The air acquires a rotational movement and, bypassing the washer 12, enters the root of the dispersed fluid stream exiting the openings 10. Intensive media contact occurs. The air flow additionally spins the flow of water droplets, increasing the path and contact time of the media. Water gives off carbon dioxide to air. There is a desorption of carbon dioxide from water / decarbonization of water /. Rotating air flow, breaking the washer 7, enters the centrifugal contact device / this is the second stage of media contact /. Intensive media contact occurs at the interface. The turbulence of the flow of media contributes to the intense mass transfer. The exhaust air is removed from the heat and mass exchanger through the pipe 8.

 The operation of the apparatus as an absorber is similar to that of a desorber. For example, in the production of sulfuric acid, sulfuric acid is supplied to the tangential nozzles 9, and gases, the content of the sulfur compound, are pumped or sucked into the nozzle 11. Upon contact of the acid with the gases, sulfur dioxide is absorbed by the acid. The concentration of sulfuric acid increases.

 The work of the heat and mass exchanger as a contact water heater or contact economizer. The pipe 11 is connected to the flue gas duct coming from the boiler or furnace, and the pipe 8 to the exhaust fan. / If the firebox is designed specifically for a heat and mass exchanger, then it will not be an economizer, but a water heater /. The pipe 9 is connected to a source of cold water. The contact of water and flue gases occurs in the same way as in the above desorber and absorber. Gases give water not only the heat of gas heating, but also the heat of condensation of the driving vapors generated during the combustion of fuel hydrocarbons. The contact economizer increases the efficiency of the boiler by 11% compared with boilers equipped with surface economizers. Heated water is used in the boiler room scheme or for production needs / for example, in hosiery / production.

The work of the heat and mass exchanger as a steam and gas generator. A steam-gas generator is an apparatus in which, upon contact of water with flue gases, a steam-gas mixture is obtained and directed to a heat exchanger where the vapors condense and give off heat to the water (for example, to the heat supply system). The principle of a steam and gas generator is described in Russian patent N 2045696 "System for the utilization of heat of combustion products" MKI G 22 and 1/18. The heat and mass exchanger serving as a steam and gas generator is connected directly to the furnace when the flue gases have a high temperature / 1200 2000 ^o C /. Therefore, the supply of flue gases is best done to the pipe 8, and the exhaust gas is exhausted from the pipe 11. Otherwise, the housing 1 will burn through from high temperature. The walls of the 4 contact centrifugal device are cooled by water. In the steam and gas generator, as in the prototype, a parallel flow of gases and water is used, and in the previous apparatuses a countercurrent flow pipe 11 can be made here both tangential and radial.

 The work of the heat and mass exchanger as a thermal deaerator. The deaerated medium / water / is supplied to the nozzles 9, and the deaerated medium / steam / is supplied to the nozzle 8. Steam and deaerated water are contacted first in a centrifugal contact device, then in the annular gap between the wall of the tank 1 and the shell 4a. Water is heated and deaerated, steam condenses. Non-condensable gases and part of the steam / vapor / are discharged through the nozzle 11. Deaerated water is discharged through the nozzle 13. Heating of the water to the saturation temperature is not accompanied by hydroshocks, even if the water is not preheated.

 The work of the heat and mass exchanger as a contact cooler for the vapor of the deaeration plant.

 Cooling water intended for condensation of water vapor is supplied to nozzles 9, and vapor from the deaerator to nozzle 8 / parallel medium flow / or to nozzle 11 / countercurrent media /. Non-condensable gases are removed into the atmosphere through the pipe 11 or through pipe b in counterflow. Cooling water heated in contact with the vapor and mixed with the condensate of the vapor is discharged through a pipe 13 to a special tank or fed to a deaerator for deaeration.

 The work of the heat and mass exchanger as a contact steam-water heater / cm. FIG. 2 /. Pipe 8 must be plugged. That is, the lid 6 is overshot due to the lack of exit from the apparatus of a gaseous medium. The heated water is supplied through the nozzles 9, and the heating steam through the nozzle 11. The process of media contact is carried out in the same way as in previous cases, the water is heated and discharged through the nozzle 13, and the steam is completely condensed. The heat and mass exchanger may be under a pressure of 5 7 or more atmospheres. Therefore, in the centrifugal contact device, the interface between media disappears. Unlike previous apparatuses, steam enters the centrifugal contact device through openings 15, since the partition / washer / 12 is continuous, without holes.

 The presence of a central hole in the bottom end cover of the centrifugal contact device significantly reduces the aerodynamic drag for the passage of the gas medium, this allows you to increase the throughput of the device in the gas environment and use it as a contact economizer and water heater, allows you to increase the unit power of the device with a relative decrease in metal consumption, reduces dimensions apparatus, allows to simplify the design of the apparatus.

 The installation of a gas medium pipe in the upper part of the tank, tangentially to the wall of the tank, makes it possible to swirl the gas stream, which increases its path and the contact surface of the media. The interchanging of the inlet and outlet pipes of the gaseous medium makes it possible to replace the parallel current of the media with a countercurrent, which intensifies the contact process of the phae / medium /. In addition, it reduces droplet entrainment of the liquid by the exhaust gas medium.

 The presence in the annular space between the vessel wall and the centrifugal contact device of the annular partition blocking a part of the annular space section allows directing the gas flow to the root of the dispersed fluid flow and thereby ensuring better media contact. The implementation of the same partition of the opaque / completely overlapping annular gap / allows the use of this apparatus as a shockless steam contact water heater, provided that additional holes are made in the shell wall of the centrifugal contact device / above the partition 12 / and the solid top cover of this device is made.

 The holes in the lower part of the side walls of the centrifugal contact device in the form of horizontal slots allow better dispersion of the liquid and preserve the tangential component of the fluid motion in the annular space, which allows for the rotational movement of the fluid at the walls of the tank and use the energy of the rotational motion to drain the spent fluid from the apparatus through the tangential branch pipe / 13 /.

 The implementation of the centrifugal contact device of two shells of different diameters, the upper of which is larger in diameter, allows for greater performance with less metal consumption. If, for an apparatus of the same gas output, it was made with a centrifugal contact device of the same diameter, then it would be equal to the diameter of the upper shell and there should be a washer at the height of the cover 3. Capacity 1 would have to do a larger diameter.

Claims (6)

 1. Heat and mass exchanger containing a housing with inlet and outlet pipes of liquid and gaseous media, made in the form of a cylindrical vertical tank with end caps, the upper of which has a Central hole, in which a centrifugal contact device, including a smaller diameter shell, is partially lowered with a gap from the bottom, having upper and lower end caps, the first of which is connected through the central hole to the gas pipe, and to the side wall, in its upper part, the tangential a fluid supply pipe in the lower part of the sleeve situated inside the tank, there are through-holes, characterized in that the bottom end cap of the centrifugal contact device has an opening that connects it with the container.  2. The heat and mass exchanger according to claim 1, characterized in that the gaseous medium nozzle is connected tangentially to the upper part of the tank above the openings of the centrifugal contact device and is the inlet of the gaseous medium, and the outlet nozzle of the gaseous medium is a nozzle on the top cover of the centrifugal contact device.  3. The heat and mass exchanger according to claim 1, characterized in that in the annular space between the walls of the tank and the centrifugal contact device at an altitude below the nozzle of the gas medium and above the holes in the centrifugal contact device there is an annular partition that overlaps part of the annular space.  4. The heat and mass exchanger according to claim 1, characterized in that the annular partition is completely overlapping the annular space, and in the housing of the centrifugal contact device above the annular partition there are additional through holes.  5. The heat and mass exchanger according to claim 1, characterized in that the holes in the lower part of the centrifugal contact device are made in the form of horizontal slots.  6. The heat and mass exchanger according to claim 1, characterized in that the centrifugal contact device has two shells of different diameters, connected to each other in series, and the shell of a larger diameter is located on top.

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