An antioxidant tail gas recovery and treatment system

Abstract

The invention discloses an antioxidant tail gas recovery and treatment system, comprising a comprehensive absorption tower, a finished hydrochloric acid tank, a vacuum unit and an alkali solution preparation tank; the comprehensive absorption tower comprises a finished liquid intermediate tank, a primary absorption section metal cylinder, a gas-liquid collector, a secondary absorption section metal cylinder, a gas-liquid mixer, a gas-liquid mixing chamber and a tertiary absorption tower which are sequentially connected from bottom to top; the invention can recycle byproduct hydrogen chloride gas to prepare hydrochloric acid, thus turning waste into treasure; at the same time, the reaction pressure of the antioxidant 168 preparation process is controlled, and then the control of the reaction pressure is realized to achieve the control of the hydrogen chloride gas generation rate and the effective control of the reaction rate of the antioxidant 168 preparation process, thereby improving the product quality of the antioxidant 168; in addition, the system of the invention has the characteristics of compact structure, small space occupation, low investment cost, simple operation, low running cost, free switching of the pressure system and the absorbent system, and easy compliance of tail gas emission.

Description

Technical Field

[0001] The invention relates to a tail gas treatment system, in particular to an antioxidant 168 tail gas recovery system. Background Art

[0002] Antioxidant 168 is a phosphite antioxidant with excellent performance. It is an indispensable heat stabilizer in resin processing. It can effectively prevent the generation of hydrogen halide during processing, thereby greatly reducing the corrosion of the mold, and can decompose the hydroperoxides formed during polymer degradation to play a good synergistic role. It is one of the commonly used phosphite auxiliary antioxidants in the world. It has good hydrolysis resistance, high temperature resistance, low volatility, strong extraction resistance, and can significantly improve the light stability of the product. At the same time, antioxidant 168 is also a relatively safe heat-stabilizing additive. It has been approved by the US FDA, and Germany, Switzerland, Japan, Italy and other countries have also allowed it to be used in food contact products. It is widely used and has good development prospects. The domestic market demand is about 1400-1600t / a, and it is growing continuously. At present, there are more than 10 units in my country that research and produce antioxidant 168 products, but most of them are small in scale and low in yield, especially the problem of tail gas recovery of by-product hydrogen chloride has not been solved.

[0003] The solubility of hydrogen chloride in water is quite large (1:450); the technology of producing hydrochloric acid by absorbing hydrogen chloride with water is relatively mature and is the most common method for treating industrial by-product hydrogen chloride. At present, the most complete hydrogen chloride absorption and tail gas treatment process system is a comprehensive absorption system consisting of: a first-stage falling film absorber, a second-stage falling film absorber, a third-stage tail gas absorption tower, a fourth-stage hydraulic jet pump, and a fifth-stage alkali washing tower; it has the advantages of strong absorption capacity and thorough tail gas treatment. Its disadvantages are: the system is huge; the one-time investment and operation costs are high.

[0004] In actual production, because this system is generally not the main process route, in order to save investment and reduce later operating costs, few companies have established a complete set of systems. Especially for process units with small production scale and unstable hydrogen chloride output, on the premise of meeting process requirements, users have higher requirements for one-time investment, space occupied, operating costs, ease of operation, etc., and have high demands and expectations for single-machine equipment with integrated design. Summary of the invention

[0005] The purpose of the present invention is to provide a tail gas recovery and treatment system in the production process of antioxidant 168. The by-product hydrogen chloride gas is recovered and utilized to produce hydrochloric acid, turning waste into treasure; at the same time, the reaction pressure in the preparation process of antioxidant 168 is controlled, and then the control of the generation rate of hydrogen chloride gas and the effective control of the reaction rate in the preparation process of antioxidant 168 are achieved through the control of the reaction pressure, thereby improving the product quality of antioxidant 168; in addition, the system of the present invention has the characteristics of compact structure, small space occupation, low investment cost, simple operation, low running cost, free switching of pressure system and absorbent system, and easy compliance of tail gas emission standards.

[0006] The technical solution of the present invention: the antioxidant tail gas recovery and treatment system comprises a comprehensive absorption tower, a finished hydrochloric acid tank, a vacuum unit and an alkali solution preparation tank;

[0007] The comprehensive absorption tower comprises a finished liquid intermediate tank, a primary absorption section metal cylinder, a gas-liquid collector, a secondary absorption section metal cylinder, a gas-liquid mixer, a gas-liquid mixing chamber and a tertiary absorption tower which are sequentially connected from bottom to top;

[0008] An absorption liquid circulation outlet and a finished liquid outlet are provided at the bottom of the finished liquid intermediate tank. The finished liquid outlet is connected to the finished hydrochloric acid tank via a first pipeline. A concentrated hydrochloric acid pump is provided on the first pipeline. An absorption liquid inlet is provided in the middle. A first hydrogen chloride gas inlet is provided on the upper part. The first hydrogen chloride gas inlet is connected to the antioxidant tail gas outlet via a ninth pipeline. A pressure regulating valve is provided on the ninth pipeline.

[0009] A first floating tube sheet is provided inside the connection between the primary absorption section metal cylinder and the finished liquid intermediate tank, and a first graphite heat exchange tube is connected to the flow hole of the first floating tube sheet. A first circulating water inlet and a first sewage outlet are provided at the lower end of the primary absorption section metal cylinder, and a first venting port and a first circulating water outlet are provided at the upper end.

[0010] The gas-liquid collector is connected to the metal cylinder of the primary absorption section via a first fixed tube sheet, the lower side of the flow hole of the first fixed tube sheet is connected to the first graphite heat exchange tube, and the upper side of the flow hole of the first fixed tube sheet is connected to the first liquid redistribution film forming device;

[0011] A second floating tube sheet is provided inside the connection between the secondary absorption section metal cylinder and the gas-liquid collector, and a second graphite heat exchange tube is connected to the flow hole of the second floating tube sheet. A second circulating water inlet and a second sewage outlet are provided at the lower end of the secondary absorption section metal cylinder, and a second vent and a second circulating water outlet are provided at the upper end; the first circulating water inlet and the second circulating water inlet are respectively connected to the circulating water inlet pipe, and the first circulating water outlet and the second circulating water outlet are respectively connected to the circulating water drain pipe;

[0012] The gas-liquid mixer is connected to the metal cylinder of the secondary absorption section via a second fixed tube sheet, the lower side of the flow hole of the second fixed tube sheet is connected to the second graphite heat exchange tube, the upper side of the flow hole of the second fixed tube sheet is connected to a second liquid redistribution film-forming device, a liquid inlet is provided at the lower side of the gas-liquid mixer, the liquid inlet is connected to the absorption liquid circulation outlet via a second pipeline, a dilute hydrochloric acid pump is provided on the second pipeline, a water supply pipeline is also connected to the second pipeline between the dilute hydrochloric acid pump and the liquid inlet, and a gas outlet is provided at the upper side of the gas-liquid mixer;

[0013] The gas-liquid mixing chamber and the gas-liquid mixer are blocked and connected, an absorption liquid outlet is provided at the lower side of the gas-liquid mixing chamber, and a second hydrogen chloride gas inlet is provided at the upper side; the absorption liquid outlet is connected to the alkali solution preparation tank via a sixth pipeline, and the gas outlet and the second hydrogen chloride gas inlet are connected to the vacuum unit via a third pipeline and a fourth pipeline respectively, valves are provided on the third pipeline and the fourth pipeline, and a fifth pipeline with a valve is provided between the third pipeline and the fourth pipeline on the side of the valve close to the comprehensive absorption tower;

[0014] The three-stage absorption tower is conductively connected with the gas-liquid mixing chamber, a packing support plate is provided at the connection, a packing layer is provided above the packing support plate, a pressing plate is provided above the packing layer, a sprayer is provided above the pressing plate, one end of the sprayer is connected with a spray liquid inlet, the spray liquid inlet is connected with the alkali solution preparation tank through a seventh pipeline, an alkali solution pump is provided on the seventh pipeline, and a waste alkali solution discharge pipe with a valve is also connected to the seventh pipeline between the alkali solution pump and the spray liquid inlet; an upper cover plate is provided on the top of the three-stage absorption tower, and an exhaust gas outlet is provided on the upper cover plate.

[0015] In the aforementioned antioxidant tail gas recovery and treatment system, the first and second baffles are respectively provided on the outer sides of the first and second graphite heat exchange tubes in the primary absorption section metal cylinder and the secondary absorption section metal cylinder.

[0016] In the aforementioned antioxidant tail gas recovery and treatment system, the first liquid redistribution film-forming device and the second liquid redistribution film-forming device are short graphite tubes, and four V-shaped notches are opened at the upper ends of the short graphite tubes.

[0017] In the antioxidant tail gas recovery and treatment system, the first floating tube sheet and the second floating tube sheet are connected to the outer tube wall in a sliding and sealing manner, and the structural form of the sliding and sealing connection is an O-ring circumferential sealing structure.

[0018] In the aforementioned antioxidant tail gas recovery and treatment system, a first liquid level gauge is provided on the finished liquid intermediate tank.

[0019] In the aforementioned antioxidant tail gas recovery and treatment system, a second liquid level gauge is provided on the gas-liquid mixing chamber.

[0020] In the aforementioned antioxidant tail gas recovery and treatment system, the packing layer is a graphite Raschig ring random packing layer.

[0021] In the aforementioned antioxidant tail gas recovery and treatment system, the flow holes of the first fixed tube sheet and the second floating tube sheet are staggered.

[0022] The above antioxidant tail gas recovery and treatment system, the vacuum unit is provided with a circulating water cooling inlet pipe and a circulating water cooling outlet pipe, and the circulating water cooling inlet pipe and the circulating water cooling outlet pipe are respectively connected to the circulating water inlet pipe and the circulating water drain pipe.

[0023] In the antioxidant tail gas recovery and treatment system, the alkali solution preparation tank is provided with an alkali solution feed pipe, and the feed pipe is provided with a stop valve assembly to realize the switching between the alkali solution and the desalted water.

[0024] The above-mentioned antioxidant tail gas recovery and treatment system, the finished hydrochloric acid tank is provided with a finished hydrochloric acid discharge pipe, and the finished hydrochloric acid discharge pipe is provided with a finished hydrochloric acid pump; the top of the finished hydrochloric acid tank is connected to the alkali solution preparation tank through an eighth pipeline, and the end of the eighth pipeline extends below the liquid surface in the alkali solution preparation tank.

[0025] Beneficial effects of the present invention

[0026] 1. Since the reaction speed is too fast in the early stage of the reaction and too slow in the later stage during the preparation of the antioxidant, both of which will affect the quality of the antioxidant, the present invention configures a vacuum unit in the tail gas recovery and treatment system and installs it at a suitable position. In the early stage of the reaction, the positive pressure value of the reaction system is controlled by a pressure regulating valve, and in the later stage, the pipeline is cut and the stop valve is changed to start the vacuum unit to provide and control the negative pressure value, so that the reaction process of the antioxidant can be reasonably controlled and adjusted to improve the quality of the antioxidant. At the same time, the negative pressure generated by the vacuum unit in the later stage can timely remove the hydrogen chloride gas in the tail gas, so that the reaction proceeds in a direction that is conducive to the formation of the product. On the basis of improving the quality, the reaction speed can also be increased to improve the production efficiency.

[0027] When the antioxidant process system cannot recycle hydrogen chloride, by-product hydrochloric acid is the most economical and effective method. The antioxidant tail gas recovery and treatment system of the present invention can recycle antioxidant 168 to prepare by-product hydrogen chloride gas and produce hydrochloric acid, turning waste into treasure.

[0028] 2. The integrated absorption tower of the present invention is a new product designed and developed in accordance with the idea of ​​"shortening the process flow by strengthening the functional design of the equipment". It integrates multiple operation units such as the traditional three-stage absorption and tail gas treatment into one device and completes them at the same time; it saves a lot of auxiliary equipment and external pipelines. It is an integrated environmentally friendly graphite equipment with the advantages of compact equipment structure, small space occupation, low investment cost, low operating cost, stable operation, simple operation, and convenient installation and maintenance.

[0029] 3. The present invention realizes the process functions of a primary falling film absorber, a secondary falling film absorber, a tertiary water absorption and a tertiary alkali washing. One device independently completes the absorption of hydrogen chloride and realizes the functions of tail gas reaching the standard and high-altitude emission. The present invention can also realize the instantaneous switching function between the tertiary alkali washing and the tertiary water absorption, and realizes the instantaneous switching function between the positive pressure and the negative pressure of the process system.

[0030] 4. The present invention has a built-in floating tube sheet structure, which effectively releases the thermal stress load of the equipment and improves the stress state of the graphite heat exchange tube bundle. The graphite material parts only bear the internal pressure load, and all the external loads of the high tower are dispersed to the metal parts, avoiding the problem of low strength of the graphite material, thereby realizing the design of the graphite material high tower.

[0031] 5. In the internal floating tube sheet structure of the present invention, the graphite tube bundle slides internally when it expands or contracts due to heat, and the overall dimensions of the equipment are not affected, and external pipes and equipment are not restricted.

[0032] 6. The graphite tube bundles in the secondary absorption section and the graphite tube bundles in the primary absorption section of the present invention have a structure design in which the centers of the flow holes on the tube sheet are arranged in an interlaced manner, which effectively realizes the functions of liquid collection and remixing without the need for a separate rain cap, further simplifying the structure of the equipment.

[0033] 7. The absorption liquid in the three-stage absorption tower of the present invention adopts a circulating absorption method and a countercurrent absorption method, so that the gas absorption effect is better and the concentration of the finished hydrochloric acid is easier to control.

[0034] The antioxidant tail gas recovery and treatment system of the present invention is also suitable for the treatment of waste gases such as ammonia, chlorine, sulfur dioxide, sulfur trioxide, etc., and is a core equipment of a "waste gas treatment type" environmental protection process system with a relatively wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Attached Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0036] Attached Figure 2 It is a structural schematic diagram of the comprehensive absorption tower of the present invention;

[0037] Attached Figure 3 This is a schematic diagram of the structure of the finished liquid intermediate tank;

[0038] Attached Figure 4 It is a structural schematic diagram of the metal cylinder of the first-stage absorption section;

[0039] Attached Figure 5 It is a structural schematic diagram of the metal cylinder of the secondary absorption section;

[0040] Attached Figure 6 It is a schematic diagram of the structure of a three-stage absorption tower;

[0041] Attached Figure 7 is a schematic structural diagram of a second liquid redistribution film-forming device;

[0042] Attached Figure 8 It is a structural schematic diagram of an existing exhaust gas treatment system.

[0043] Explanation of reference numerals: 1-absorption liquid circulation outlet; 2-first liquid level gauge; 3-finished liquid intermediate tank; 4-first hydrogen chloride gas inlet; 5-first floating tube sheet; 6-first circulation water inlet; 7-first baffle; 8-first vent; 9-first fixed tube sheet; 10-gas-liquid collector; 11-second circulation water inlet; 12-second baffle; 13-second vent; 14-liquid inlet; 15-gas-liquid mixer; 16-absorption liquid outlet; 17-gas-liquid mixer chamber; 18-pressing plate; 19-sprinkler; 20-upper cover; 21-gas outlet; 22-spraying liquid inlet; 23-packing layer; 24-third-stage absorption tower; 25-packing support plate; 26-second liquid level gauge; 27-second hydrogen chloride gas inlet; 28-gas outlet, 29-second liquid redistribution film-forming device; 30-second fixed tube sheet; 31-second circulating water outlet; 32-secondary absorption section metal cylinder; 33-second graphite heat exchange tube; 34-second sewage outlet ; 35-second floating tube sheet; 36-first liquid redistribution film former; 37-first circulating water outlet; 38-first absorption section metal cylinder; 39-first graphite heat exchange tube; 40-first sewage outlet; 41-upper pipe flange; 42-absorption liquid inlet; 43-finished liquid outlet, 44-comprehensive absorption tower, 45-finished hydrochloric acid tank, 46-vacuum unit, 47-alkali solution preparation tank, 48-circulating water inlet pipe, 49-circulating water drain pipe, 50-second pipeline, 51 -dilute hydrochloric acid pump, 52-water supply pipeline, 53-fourth pipeline, 54-third pipeline, 55-fifth pipeline, 56-circulating water cooling inlet pipe, 57-circulating water cooling outlet pipe, 58-seventh pipeline, 59-waste alkali liquid discharge pipe, 60-alkali liquid pump, 61-sixth pipeline, 62-alkali liquid feed pipe, 63-first pipeline, 64-finished hydrochloric acid discharge pipe, 65-concentrated hydrochloric acid pump, 66-finished hydrochloric acid pump, 67-eighth pipeline, 68-ninth pipeline, 69-pressure regulating valve. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0045] Embodiments of the present invention

[0046] An antioxidant tail gas recovery and treatment system, as shown in the attached Figure 1-7As shown, it includes a comprehensive absorption tower 44, a finished hydrochloric acid tank 45, a vacuum unit 46 and an alkali solution preparation tank 47; the comprehensive absorption tower 44 includes a finished liquid intermediate tank 3, a primary absorption section metal cylinder 38, a gas-liquid collector 10, a secondary absorption section metal cylinder 32, a gas-liquid mixer 15, a gas-liquid mixing chamber 17 and a tertiary absorption tower 24 connected in sequence from bottom to top; the finished liquid intermediate tank 3, the primary absorption section metal cylinder 38, the gas-liquid collector 10, the secondary absorption section metal cylinder 32, the gas-liquid mixer 15, the gas-liquid mixing chamber 17 and the tertiary absorption tower 24 are all made of steel lined polymer materials, and the upper end of the finished liquid intermediate tank 3 is connected through an upper pipe The flange 41 is connected to the primary absorption section metal cylinder 38, and the primary absorption section metal cylinder 38 and the gas-liquid collector 10, the gas-liquid collector 10 and the secondary absorption section metal cylinder 32, the secondary absorption section metal cylinder 32 and the gas-liquid mixer 15, and the gas-liquid mixer 15 and the gas-liquid mixing chamber 17 are all flange-connected; the bottom of the finished liquid intermediate tank 3 is provided with an absorption liquid circulation outlet 1 and a finished liquid outlet 43, the finished liquid outlet 43 is connected to the finished hydrochloric acid tank 45 through a first pipeline 63, a concentrated hydrochloric acid pump 65 is provided on the first pipeline 63, an absorption liquid inlet 42 is provided in the middle, a first hydrogen chloride gas inlet 4 is provided on the upper part, and the first hydrogen chloride gas The inlet 4 is connected to the antioxidant tail gas outlet via a ninth pipeline 68, and a pressure regulating valve 69 is provided on the ninth pipeline 68; a first floating tube sheet 5 is provided inside the connection between the primary absorption section metal cylinder 38 and the finished liquid intermediate tank 3, and a first graphite heat exchange tube 39 is connected to the flow hole of the first floating tube sheet 5; a first circulating water inlet 6 and a first sewage outlet 40 are provided at the lower end of the primary absorption section metal cylinder 38, and a first vent 8 and a first circulating water outlet 37 are provided at the upper end; the gas-liquid collector 10 is connected to the primary absorption section metal cylinder 38 via a first fixed tube sheet 9, and the lower side of the flow hole of the first fixed tube sheet 9 is connected to the first graphite heat exchange tube 39, A first liquid redistribution film former 36 is connected to the upper side of the flow hole of the first fixed tube sheet 9; a second floating tube sheet 35 is provided inside the connection between the secondary absorption section metal cylinder 32 and the gas-liquid collector 10, and a second graphite heat exchange tube 33 is fixedly connected inside the flow hole of the second floating tube sheet 35; a second circulating water inlet 11 and a second sewage outlet 34 are provided at the lower end of the secondary absorption section metal cylinder 32, and a second vent 13 and a second circulating water outlet 31 are provided at the upper end; the first circulating water inlet 6 and the second circulating water inlet 11 are respectively connected to a circulating water inlet pipe 48, and the first circulating water outlet 37 and the second circulating water outlet 31 are respectively connected to a circulating water drain pipe 49;The gas-liquid mixer 15 is connected to the secondary absorption section metal cylinder 32 via a second fixed tube sheet 30. The lower side of the flow hole of the second fixed tube sheet 30 is fixedly connected to the second graphite heat exchange tube 33. The upper side of the flow hole of the second fixed tube sheet 30 is connected to the second liquid redistribution film forming device 29. The lower side of the gas-liquid mixer 15 is provided with a liquid inlet 14. The liquid inlet 14 is connected to the absorption liquid circulation outlet 1 via a second pipeline 50. The second pipeline 50 is provided with a dilute hydrochloric acid pump 51. The dilute hydrochloric acid pump 51 is connected to the absorption liquid circulation outlet 1 via a second pipeline 50. A water supply pipe 52 is also connected to the second pipe 50 between the liquid inlets 14, a gas outlet 28 is provided on the upper side of the gas-liquid mixer 15, and the upper part of the second liquid redistribution film-forming device 29 is higher than the liquid inlet 14150-200mm; the gas-liquid mixing chamber 17 and the gas-liquid mixer 15 are blocked and connected, an absorption liquid outlet 16 is provided on the lower side of the gas-liquid mixing chamber 17, and a second hydrogen chloride gas inlet 27 is provided on the upper side; the absorption liquid outlet 16 is connected to the alkali solution preparation tank 47 through a sixth pipe 61, and the gas outlet 28 and the second hydrogen chloride gas inlet 27 are connected to the vacuum unit 46 through a third pipe 54 and a fourth pipe 53 respectively, and valves are provided on the third pipe 54 and the fourth pipe 53, and a fifth pipe 55 with a valve is provided between the third pipe 54 and the fourth pipe 53 on the side of the valve close to the comprehensive absorption tower 44; the three-stage absorption tower 24 is connected to the gas-liquid mixing chamber 17, and a packing support plate 25 is provided at the connection, and a packing layer 23 is provided above the packing support plate 25, and the packing layer A pressing plate 18 is arranged above the pressing plate 18, a sprayer 19 is arranged above the pressing plate 18, one end of the sprayer 19 is connected to a spray liquid inlet 22, the spray liquid inlet 22 is connected to the alkali solution preparation tank 47 via a seventh pipeline 58, an alkali solution pump 60 is arranged on the seventh pipeline 58, and a waste alkali solution discharge pipe 59 with a valve is also connected to the seventh pipeline 58 between the alkali solution pump 60 and the spray liquid inlet 22; an upper cover plate 20 is arranged at the top of the three-stage absorption tower 24, and an exhaust gas outlet 21 is arranged on the upper cover plate 20. ;

[0047] The working process of the above embodiment is:

[0048] 1. Gas flow path

[0049] The hydrogen chloride tail gas continuously enters the upper space of the finished liquid intermediate tank 3 through the first hydrogen chloride gas inlet 4. In the early stage of the reaction, the discharge speed of the byproduct hydrogen chloride gas is controlled by the pressure regulating valve 69, thereby controlling the positive pressure value of the antioxidant reaction system. The hydrogen chloride tail gas further flows upward into the first graphite heat exchange tube 39 of the graphite heat exchange tube bundle of the primary absorption section, and performs countercurrent contact mass transfer with the absorption liquid film flowing down along the inner wall of the first graphite heat exchange tube 39. While the hydrogen chloride gas is absorbed, absorption heat is released, and the absorption heat is taken away by the shell cooling water on the service side of the primary absorption section through the partition wall heat exchange method, so that the absorption proceeds in a favorable direction.

[0050] The unabsorbed hydrogen chloride gas continues to enter the gas-liquid manifold 10 upward, is mixed and redistributed, and flows upward into the second graphite heat exchange tube 33 of the graphite heat exchange tube bundle of the secondary absorption section, and performs countercurrent contact mass transfer with the absorption liquid film flowing down along the inner wall of the second graphite heat exchange tube 33. While the hydrogen chloride gas is absorbed, absorption heat is released, and the absorption heat is taken away by the shell-side cooling water on the service side of the secondary absorption section through inter-wall heat exchange, so that the absorption proceeds in a favorable direction.

[0051] The remaining unabsorbed trace hydrogen chloride gas and impurity tail gas continue to enter the gas-liquid mixer 15 upward, and after being collected and mixed, they flow out of the gas-liquid mixer 15 through the gas outlet 28, and then enter the gas-liquid mixing chamber 17 at the bottom of the three-stage absorption tower 24 through the third pipeline 54, the fifth pipeline 55, the fourth pipeline 53 and the second hydrogen chloride gas inlet 27 in sequence; further upward through the graphite Raschig ring random packing layer 23, countercurrent contact, mass transfer and heat transfer are carried out with the absorption liquid on the surface of the packing, the residual trace hydrogen chloride gas in the tail gas is absorbed, and the released heat energy is also taken away by the absorption liquid, and the impurity tail gas that is difficult to dissolve is discharged at high altitude through the gas outlet 21 provided on the upper cover plate 20; the tail gas is completed. The process tasks of absorbing hydrogen chloride gas and treating tail gas are as follows; in this process, when the antioxidant reaction is in the initial stage, the tail gas is discharged by relying on the internal positive pressure and flows through the above-mentioned path. At this time, the vacuum unit 46 does not need to work, that is, the valves on the third pipeline 54 and the fourth pipeline 53 are closed, and the valve on the fifth pipeline 55 is opened, and the tail gas flows naturally; when the reaction proceeds to the later stage, the tail gas generated in the reaction device is insufficient, and the hydrogen chloride gas is very little, but it needs to be discharged in time. At this time, the vacuum unit 46 and the valves on the third pipeline 54 and the fourth pipeline 53 are opened, and the valve on the fifth pipeline 55 is closed, and the negative pressure generated by the vacuum unit 46 is used to extract the tail gas in time and treat it.

[0052] 2. Absorption liquid flow path

[0053] Deionized water enters the gas-liquid mixer 15 through the water supply pipe 52. The liquid level rises by 150-200 mm and then gradually stabilizes. It reaches the upper end of the liquid film distributor 29, enters the second liquid and is then divided into the inner wall of the film distributor 29 to form an acidic absorption liquid film. It further descends and enters the second graphite heat exchange tube 33 of the graphite heat exchange tube bundle of the secondary absorption section, and performs countercurrent contact mass transfer with the tail gas that continues to flow upward in the second graphite heat exchange tube 33 and has not been absorbed by the primary absorption section. After the acidic absorption liquid film absorbs the hydrogen chloride gas, the concentration of hydrochloric acid gradually increases, and gradually becomes dilute hydrochloric acid and flows downward into the gas-liquid collector 10.

[0054] In this process section, the absorption heat is released while the hydrogen chloride gas is absorbed, and the temperature of the dilute hydrochloric acid rises. At the same time, the shell-side cooling water on the service side of the secondary absorption section enters the secondary absorption section metal cylinder 32 through the second circulating water inlet 11, and performs inter-wall heat exchange between the inner and outer walls of the second graphite heat exchange tube 33 of the graphite heat exchange tube bundle in the secondary absorption section, so as to take away the absorption heat in time and control the temperature of the dilute hydrochloric acid from continuing to rise, so that the absorption process proceeds in a favorable direction. The shell-side cooling water on the service side that completes the heat exchange process task flows out of the secondary absorption section metal cylinder 32 through the second circulating water outlet 31.

[0055] After the dilute hydrochloric acid flows into the gas-liquid collector 10, the liquid collection and remixing function is realized.

[0056] After the liquid level rises, it gradually stabilizes and reaches the upper end of the first liquid redistribution film-forming device 36. It enters the inner wall of the first liquid redistribution film-forming device 36 through the upper end to form a downward dilute hydrochloric acid liquid film, and further descends into the first graphite heat exchange tube 39 of the graphite heat exchange tube bundle of the primary absorption section, and performs countercurrent contact mass transfer with the upward hydrogen chloride gas to be treated in the first graphite heat exchange tube 39. After the dilute hydrochloric acid liquid film absorbs the hydrogen chloride gas, the concentration of hydrochloric acid gradually increases, and gradually becomes slightly concentrated hydrochloric acid and flows downward into the finished liquid intermediate tank 3, completing the process task of absorbing hydrogen chloride.

[0057] In this process section, the absorption heat is released while the hydrogen chloride gas is absorbed, and the temperature of the concentrated hydrochloric acid rises. At the same time, the shell-side cooling water on the service side of the primary absorption section enters the metal cylinder 38 of the primary absorption section through the first circulating water inlet 6, and performs inter-wall heat exchange between the inner and outer walls of the first graphite heat exchange tube 39 of the graphite heat exchange tube bundle of the primary absorption section, so as to take away the absorption heat in time and control the temperature of the concentrated hydrochloric acid from continuing to rise, so that the absorption process proceeds in a favorable direction. The shell-side cooling water on the service side that completes the heat exchange process task flows out of the metal cylinder 38 of the secondary absorption section through the first circulating water outlet 37.

[0058] Initially, the hydrochloric acid solution flowing into the finished liquid intermediate tank 3 does not meet the standard of concentrated hydrochloric acid, so the hydrochloric acid solution in the finished liquid intermediate tank 3 is pumped into the gas-liquid mixer 15 through the dilute hydrochloric acid pump 51 to repeatedly absorb hydrogen chloride. When it reaches the standard, it is transported to the finished hydrochloric acid tank 45 for storage through the finished hydrochloric acid pump 66. At the same time, when the tail gas enters the tertiary absorption tower 24, the alkali in the alkali preparation tank 47 is transported to the sprayer 19 through the alkali pump 60 to spray the tail gas so that the tail gas reaches the final emission standard. The alkali solution is then returned to the alkali solution preparation tank 47 through the sixth pipeline 61. When the alkali solution cannot be reused, it is discharged from the waste alkali solution discharge pipe 59. However, this is only limited to the case where the tail gas enters the tertiary absorption tower 24 and contains a lot of hydrogen chloride or other harmful acidic gases. The use of alkali solution can improve the effect of tail gas treatment; when the hydrogen chloride or other harmful gases entering the tertiary absorption tower 24 can be absorbed by water, the alkali solution in the alkali solution preparation tank 47 can be replaced with deionized water, and water washing can be carried out according to the alkali washing process.

[0059] Preferably, the first baffle 7 and the second baffle 12 are respectively provided on the outer sides of the first graphite heat exchange tube 39 and the second graphite heat exchange tube 33 in the first absorption section metal cylinder 38 and the second absorption section metal cylinder 32. Under the action of the first baffle 7 and the second baffle 12, the flow direction of the cooling water can be controlled and the heat exchange efficiency can be improved.

[0060] Preferably, the first liquid redistribution film forming device 36 and the second liquid redistribution film forming device 29 are short graphite tubes with four V-shaped notches at the upper end. The absorption liquid enters the inner wall of the liquid redistribution film forming device tangentially and vertically through the liquid flow channel with four V-shaped notches at the upper end, forming an acid absorption liquid film that swirls downward.

[0061] Preferably, the first floating tube sheet 5 and the second floating tube sheet 35 are connected to the outer tube wall in a sliding and sealing manner, and the structural form of the sliding and sealing connection is an O-ring circumferential sealing structure.

[0062] Preferably, the finished liquid intermediate tank 3 is provided with a first liquid level meter 2. The flow rate and liquid level of the acidic absorption liquid in the finished liquid intermediate tank 3 are observed and controlled by the first liquid level meter 2.

[0063] Preferably, a second liquid level meter 26 is provided on the gas-liquid mixing chamber 17. The flow rate and liquid level of the acidic absorption liquid in the gas-liquid mixing chamber 17 are observed and controlled by the second liquid level meter 26.

[0064] Preferably, the flow holes of the first fixed tube sheet 9 and the second floating tube sheet 35 are staggered. Since the flow holes of the first fixed tube sheet 9 and the second floating tube sheet 35 are staggered, after the 17% dilute hydrochloric acid flows into the gas-liquid collector 10, it can directly fall to the bottom of the gas-liquid collector 10 without the need for a rain cap, thereby realizing the liquid collection and remixing function.

[0065] Preferably, the vacuum unit 46 is provided with a circulating water cooling inlet pipe 56 and a circulating water cooling outlet pipe 57, and the circulating water cooling inlet pipe 56 and the circulating water cooling outlet pipe 57 are respectively connected to the circulating water inlet pipe 48 and the circulating water drain pipe 49. When the exhaust gas passes through the vacuum unit 46, the circulating water cooling inlet pipe 56 and the circulating water cooling outlet pipe 57 take away the heat from the vacuum unit 46 in time.

[0066] Preferably, the alkali solution preparation tank 47 is provided with an alkali solution feeding pipe 62 .

[0067] Preferably, the finished hydrochloric acid tank 45 is provided with a finished hydrochloric acid discharge pipe 64, and the finished hydrochloric acid discharge pipe 64 is provided with a finished hydrochloric acid pump 66; the top of the finished hydrochloric acid tank 45 is connected to the alkali solution preparation tank 47 via an eighth pipe 67, and the end of the eighth pipe 67 extends below the liquid surface in the alkali solution preparation tank 47. During the storage of concentrated hydrochloric acid, a small amount of hydrogen chloride gas will be generated. If it is directly discharged from the finished hydrochloric acid tank 45, it will cause air pollution. Therefore, the hydrogen chloride gas is introduced below the liquid surface in the alkali solution preparation tank 47 through the eighth pipe 67 to complete the water seal and avoid overflow.

[0068] By comparison Figure 1 and Figure 8 It can be seen that the structural integrity of the system of the present application is stronger; the exhaust gas recovery and treatment system of model DN400×9500 designed and developed by the present application is compared with the existing system in terms of cost performance in 13 aspects, see Table 1 for details.

[0069] Table 1: Performance comparison between the system of the present invention and the existing system

[0070]

[0071]

[0072]

[0073] Note: Based on the performance comparison of the above 13 factors, the system of the present invention has superior performance and low cost, and has more comprehensive advantages compared with similar functional products on the market.

[0074] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An antioxidant tail gas recovery and treatment system, characterized in that: It includes a comprehensive absorption tower (44), a finished hydrochloric acid tank (45), a vacuum unit (46) and an alkali solution preparation tank (47); The integrated absorption tower (44) comprises a finished liquid intermediate tank (3), a primary absorption section metal cylinder (38), a gas-liquid collector (10), a secondary absorption section metal cylinder (32), a gas-liquid mixer (15), a gas-liquid mixing chamber (17) and a tertiary absorption tower (24) which are sequentially connected from bottom to top; The bottom of the finished liquid intermediate tank (3) is provided with an absorption liquid circulation outlet (1) and a finished liquid outlet (43); the finished liquid outlet (43) is connected to the finished hydrochloric acid tank (45) via a first pipeline (63); a concentrated hydrochloric acid pump (65) is provided on the first pipeline (63); an absorption liquid inlet (42) is provided in the middle; a first hydrogen chloride gas inlet (4) is provided on the upper part; the first hydrogen chloride gas inlet (4) is connected to the antioxidant tail gas outlet via a ninth pipeline (68); and a pressure regulating valve (69) is provided on the ninth pipeline (68); A first floating tube sheet (5) is provided inside the connection between the primary absorption section metal cylinder (38) and the finished liquid intermediate tank (3), a first graphite heat exchange tube (39) is connected to the flow hole of the first floating tube sheet (5), a first circulating water inlet (6) and a first sewage outlet (40) are provided at the lower end of the primary absorption section metal cylinder (38), and a first venting port (8) and a first circulating water outlet (37) are provided at the upper end; The gas-liquid collector (10) is connected to the primary absorption section metal cylinder (38) via a first fixed tube sheet (9), the lower side of the flow hole of the first fixed tube sheet (9) is connected to the first graphite heat exchange tube (39), and the upper side of the flow hole of the first fixed tube sheet (9) is connected to a first liquid redistribution film forming device (36); A second floating tube sheet (35) is provided inside the connection between the secondary absorption section metal cylinder (32) and the gas-liquid collector (10); a second graphite heat exchange tube (33) is connected to the flow hole of the second floating tube sheet (35); a second circulating water inlet (11) and a second sewage outlet (34) are provided at the lower end of the secondary absorption section metal cylinder (32); a second vent (13) and a second circulating water outlet (31) are provided at the upper end; the first circulating water inlet (6) and the second circulating water inlet (11) are respectively connected to a circulating water inlet pipe (48); and the first circulating water outlet (37) and the second circulating water outlet (31) are respectively connected to a circulating water drain pipe (49); The gas-liquid mixer (15) is connected to the secondary absorption section metal cylinder (32) via a second fixed tube sheet (30); the lower side of the flow hole of the second fixed tube sheet (30) is connected to the second graphite heat exchange tube (33); the upper side of the flow hole of the second fixed tube sheet (30) is connected to a second liquid redistribution film forming device (29); a liquid inlet (14) is provided on the lower side of the gas-liquid mixer (15); the liquid inlet (14) is connected to the absorption liquid circulation outlet (1) via a second pipeline (50); a dilute hydrochloric acid pump (51) is provided on the second pipeline (50); a water supply pipeline (52) is also connected to the second pipeline (50) between the dilute hydrochloric acid pump (51) and the liquid inlet (14); and a gas outlet (28) is provided on the upper side of the gas-liquid mixer (15); The gas-liquid mixing chamber (17) and the gas-liquid mixer (15) are blocked and connected. An absorption liquid outlet (16) is provided at the lower side of the gas-liquid mixing chamber (17), and a second hydrogen chloride gas inlet (27) is provided at the upper side. The absorption liquid outlet (16) is connected to the alkali solution preparation tank (47) via a sixth pipeline (61). The gas outlet (28) and the second hydrogen chloride gas inlet (27) are connected to the vacuum unit (46) via a third pipeline (54) and a fourth pipeline (53), respectively. Valves are provided on the third pipeline (54) and the fourth pipeline (53). A fifth pipeline (55) with a valve is provided between the third pipeline (54) and the fourth pipeline (53) on the side of the valve close to the comprehensive absorption tower (44); The three-stage absorption tower (24) is connected to the gas-liquid mixing chamber (17), and a packing support plate (25) is provided at the connection point. A packing layer (23) is provided above the packing support plate (25), and a material pressing plate (18) is provided above the material pressing plate (18). A sprayer (19) is provided above the material pressing plate (18), and one end of the sprayer (19) is connected to a spray liquid inlet (22). The spray liquid inlet (22) is connected to the alkali solution preparation tank (47) via a seventh pipeline (58). An alkali solution pump (60) is provided on the seventh pipeline (58), and a waste alkali solution discharge pipe (59) with a valve is also connected to the seventh pipeline (58) between the alkali solution pump (60) and the spray liquid inlet (22); an upper cover plate (20) is provided at the top of the three-stage absorption tower (24), and an exhaust gas outlet (21) is provided on the upper cover plate (20); The first baffle plate (7) and the second baffle plate (12) are respectively disposed on the outer sides of the first graphite heat exchange tube (39) and the second graphite heat exchange tube (33) in the first absorption section metal cylinder (38) and the second absorption section metal cylinder (32); The flow holes of the first fixed tube sheet (9) and the second floating tube sheet (35) are arranged in a staggered manner.

2. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The first liquid redistribution film-forming device (36) and the second liquid redistribution film-forming device (29) are short graphite tubes, and four V-shaped notches are formed at the upper ends of the short graphite tubes.

3. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The first floating tube sheet (5) and the second floating tube sheet (35) are connected to the outer tube wall in a sliding and sealing manner, and the structural form of the sliding and sealing connection is an O-ring circumferential sealing structure.

4. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The finished liquid intermediate tank (3) is provided with a first liquid level meter (2); the gas-liquid mixing chamber (17) is provided with a second liquid level meter (26).

5. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The packing layer (23) is a graphite Raschig ring random packing layer.

6. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The vacuum unit (46) is provided with a circulating water cooling inlet pipe (56) and a circulating water cooling outlet pipe (57), and the circulating water cooling inlet pipe (56) and the circulating water cooling outlet pipe (57) are respectively connected to the circulating water inlet pipe (48) and the circulating water outlet pipe (49).

7. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The alkali solution preparation tank (47) is provided with an alkali solution feeding pipe (62).

8. The antioxidant tail gas recovery and treatment system according to claim 1, characterized in that: The finished hydrochloric acid tank (45) is provided with a finished hydrochloric acid discharge pipe (64), and the finished hydrochloric acid discharge pipe (64) is provided with a finished hydrochloric acid pump (66); the top of the finished hydrochloric acid tank (45) is connected to the alkali solution preparation tank (47) via an eighth pipeline (67), and the end of the eighth pipeline (67) extends below the liquid level in the alkali solution preparation tank (47).

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