Tail gas condenser capable of providing acid-free steam

Abstract

The invention provides a tail gas condenser capable of providing acid-free steam. The tail gas condenser comprises a tank body, a steam outlet formed in the top of the tank body, an acid liquid outlet formed in the bottom of the tank body, a tee joint used for supplying waste gas into the tank body and a water inlet pipe used for supplying cooling water into the tank body. A sealing plate structure for isolating waste gas and cooling water is arranged in a tank body, so that the sealing plate structure comprises a pipe plate spanning in the tank body and a plurality of independent heat pipes penetrating through the pipe plate in a sealing manner, the pipe plate is connected with the inner wall of the tank body in a sealing manner, and the pipe plate is higher than a tee joint and lower than a water inlet pipe; the heat pipe is a straight pipe which extends up and down and is provided with two closed ends, and the heat pipe is filled with a heat exchange medium and a capillary object, so that the upper part of the heat pipe extends into the upper cavity to be in contact with cooling water, and the lower part of the heat pipe extends into the lower cavity to be in contact with waste gas; heat in waste gas can be transmitted through the heat pipe, cooling water is changed into steam, and acidic substances in the waste gas are prevented from entering the steam.

Description

Technical Field

[0001] The present invention relates to the technical field of tail gas treatment, and in particular to a tail gas condenser capable of providing acid-free steam. Background Art

[0002] The tail gas condenser is one of the core equipment in the rare metal mineral resource extraction system. It is widely used in the extraction of lithium metal, titanium metal, nickel metal and zirconium metal. In the rare metal mineral resource extraction system, the tail gas condenser is generally connected to the preheater and reactor to recover the acid and heat in the acidic tail gas to reduce the overall energy consumption of the system.

[0003] The extraction process of rare metal mineral resources is usually as follows: after the ore is crushed, it enters the grinding process and is ground into slurry. The slurry is heated to a certain temperature. The heating equipment is low-temperature, medium-temperature, and high-temperature slurry preheaters. In these equipment, the slurry is continuously heated. After being heated to a certain temperature, it enters the reactor to react with dilute sulfuric acid. The metal undergoes a chemical reaction in the dilute acid to generate NiSO4 and other sulfate metal salts. Under the action of the catalyst, it continues to react. In this process, acidic gases are volatilized in the reactor and the low-temperature, medium-temperature, and high-temperature slurry preheaters. Since the preheater uses steam for heating, the steam and acidic gases in the reactor are both heat energy sources in the system. These steam and acidic gases are introduced into the tail gas condenser, condensed by the tail gas condenser, and the heat and acidic substances are recovered and returned to the system for secondary use.

[0004] The existing tail gas condenser structure is as follows Figure 1 As shown, it includes a tank body 1, a water inlet structure 30 for supplying cooling water to the tank body 1, a common tee 29 for supplying exhaust gas to the tank body, a plurality of baffles 28 staggered in the tank body, an acid outlet 3 provided at the bottom of the tank body, and a steam outlet 2 provided at the top of the tank body. The cooling water flows in from the upper part of the tank body 1, and from top to bottom, it is continuously deflected back and forth on these baffles 28 to form a shape similar to a waterfall. The acidic high-temperature exhaust gas from the low-temperature, medium-temperature, and high-temperature preheaters and reactors enters from the lower part of the tank body 1, and from bottom to top, it is fully in contact with the cooling water forming the waterfall. The acid gas in the acidic high-temperature exhaust gas is quickly cooled. Water contacts and forms a mixed solution which is discharged from the bottom acid outlet 3. Part of the cooling water is heated and evaporated by the acid-containing high-temperature exhaust gas to form steam which is discharged from the top steam outlet 2. Due to the mixing of cooling water, the concentration of acidic substances in the mixed liquid is low and needs to be further purified before it can be used for the second time, which is inefficient. For steam, the evaporated cooling water will also take away part of the acidic substances to form acid-containing steam. At the same time, the acid-containing high-temperature exhaust gas will also tear the waterfall and rush directly upward during the rising process, which increases the acid content of the discharged steam. When it is used for the second time, it is easy to cause corrosion to subsequent equipment, which brings risks to the safe operation of the equipment. Summary of the Invention

[0005] The object of the present invention is to overcome one or more disadvantages in the prior art and to provide a tail gas condenser capable of providing acid-free steam.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is to provide an acid-free steam exhaust condenser, comprising a tank body, a steam outlet provided at the top of the tank body, an acid liquid outlet provided at the bottom of the tank body, a tee for supplying exhaust gas to the tank body, and a water inlet pipe for supplying cooling water to the tank body; a sealing plate structure is provided in the tank body for isolating exhaust gas and cooling water, the sealing plate structure comprises a tube sheet across the tank body, and a plurality of independent heat pipes sealed and passed through the tube sheet, the tube sheet is sealedly connected to the inner wall of the tank body, and its height is higher than the tee and lower than the water inlet pipe, dividing the cavity in the tank body into an upper cavity connected to the water inlet pipe and a lower cavity connected to the tee, the heat pipe is a straight pipe extending up and down and closed at both ends, and its interior is filled with heat exchange medium and capillary, the upper part of the heat pipe extends into the upper cavity and contacts with the cooling water supplied by the water inlet pipe, and the lower part of the heat pipe extends into the lower cavity and contacts with the exhaust gas supplied by the tee.

[0007] Preferably, the heat pipe further comprises a spiral fin spirally wound around the outer side of the upper portion thereof, the spiral angle of the spiral fin is 30-42 degrees, and the overall smoothness of the heat pipe is not greater than 1.6 microns.

[0008] Preferably, the heat exchange medium is sodium and potassium salts, and the capillaries are polytetrafluoroethylene fibers and aromatic fibers.

[0009] Preferably, the internal cavity of the tee includes a horizontal cavity and an inclined cavity arranged to be inclined from top to bottom, one end of the horizontal cavity is connected to the reactor, and the other end is connected to the lower cavity, the upper end of the inclined cavity is connected to the preheater, and the lower end is connected to the horizontal cavity.

[0010] Further preferably, the horizontal cavity is larger at both ends and smaller in the middle, dividing the horizontal cavity into a high-pressure gas zone at the inlet end, a lafayette throat zone in the middle section, and a diffusion injection zone at the outlet end. When the reactor introduces acid-containing high-temperature exhaust gas into the high-pressure gas zone, a vacuum zone is formed in the diffusion injection zone near the lafayette throat zone. There are multiple inclined cavities to distinguish and connect to the low-temperature, medium-temperature and high-temperature preheaters, and the lower ends of multiple inclined cavities are all connected to the vacuum zone.

[0011] Further preferably, the diffusion spray zone extends along the tangential direction of the tank body, so that the acid-containing high-temperature exhaust gas ejected from the diffusion spray zone forms a circumferential airflow in the tank body, and drives the acid liquid condensed at the bottom of the tank body to produce a circumferential flow, thereby enhancing the convective heat transfer coefficient.

[0012] Preferably, a shell and tube superheater is further provided in the tank body, the shell and tube superheater is located above the heat pipe, the inlet of the shell and tube superheater is connected to the high-temperature preheater, and the outlet of the shell and tube superheater is connected to the lower cavity.

[0013] Preferably, the water inlet pipe is arranged close to the inner wall of the tank body, the water inlet pipe is semi-annular or annular, the port of the water inlet pipe inside the tank body is closed, and the outer wall of the water inlet pipe facing the heat pipe is provided with multiple water spray holes.

[0014] Preferably, the tank body includes a cylindrical barrel, an elliptical head connected to the top of the barrel and a lower cone connected to the bottom of the barrel, the steam outlet is opened at the center of the elliptical head, the lower cone is located below the tee, a skirt is provided on the outside of the lower cone, and the acid outlet is opened at the bottom center of the lower cone.

[0015] Further preferably, the cylinder is provided with a first liquid level tube and a second liquid level tube extending up and down, the two ends of the first liquid level tube are connected to the upper cavity, and are used to detect the coolant level in the upper cavity, the middle part of the first liquid level tube is connected to an overflow pipe, and the end of the overflow pipe away from the first liquid level tube is connected to the water inlet pipe, and the two ends of the second liquid level tube are connected to the lower cavity, and are used to detect the acid liquid level in the lower cavity.

[0016] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0017] 1. It can realize the separation and efficient collection of heat and acidic substances in acid-containing high-temperature exhaust gas.

[0018] 2. It can prevent the entry of acidic substances in acid-containing high-temperature exhaust gas, so that the steam formed by heating the cooling water is completely acid-free, obtaining acid-free steam, thereby extending the service life of the equipment.

[0019] 3. It can prevent the mixing of cooling water into the condensed acid solution, thereby maintaining the concentration of the acid solution and facilitating subsequent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of a tail gas condenser in the prior art.

[0021] Figure 2 It is a structural diagram of a preferred embodiment of the present invention.

[0022] Figure 3 yes Figure 2 Schematic diagram of two structures of medium heat pipe, where the left one is the inferior solution and the right one is the superior solution.

[0023] Figure 4 yes Figure 2 A partial enlarged schematic diagram of the middle tee.

[0024] Figure 5 yes Figure 2 Schematic cross-section of the middle and lower cavity.

[0025] Figure 6 yes Figure 2 A partial enlarged schematic diagram of the middle water inlet pipe.

[0026] Among them: 1. Tank body; 2. Steam outlet; 3. Acid outlet; 4. Tee; 5. Water inlet pipe; 6. Tube sheet; 7. Heat pipe; 8. Upper cavity; 9. Lower cavity; 10. Flat fins; 11. Spiral fins; 12. Horizontal cavity; 13. Inclined cavity; 14. High-pressure gas area; 15. Lafa tube throat area; 16. Diffusion injection area; 17. Vacuum area; 18. Shell and tube superheater; 19. Gas-liquid separator; 20. Water spray hole; 21. Cylinder; 22. Elliptical head; 23. Lower cone; 24. Skirt; 25. First liquid level pipe; 26. Second liquid level pipe; 27. Overflow pipe; 28. Baffle; 29. Ordinary tee; 30. Water inlet structure. DETAILED DESCRIPTION

[0027] like Figures 2 to 6 As shown, the tail gas condenser capable of providing acid-free steam provided by the present invention comprises a tank body 1, a steam outlet 2 provided at the top of the tank body 1, an acid liquid outlet 3 provided at the bottom of the tank body 1, a tee 4 for supplying exhaust gas to the tank body 1, and a water inlet pipe 5 for supplying cooling water to the tank body 1; wherein, a sealing plate structure is provided in the tank body 1 for isolating the exhaust gas supplied by the tee 4 and the cooling water supplied by the water inlet pipe 5, the sealing plate structure comprises a tube sheet 6 spanning the tank body 1, a plurality of independent heat pipes 7 sealed and passed through the tube sheet 6, and the tube sheet 6 is sealed against the inner wall of the tank body 1. The sealed connection is higher than the tee 4 and lower than the water inlet pipe 5, dividing the cavity in the tank body 1 into an upper cavity 8 connected to the water inlet pipe 5 and a lower cavity 9 connected to the tee 4. The heat pipe 7 is a straight tube extending up and down and closed at both ends. The interior is filled with a heat exchange medium and capillaries. Specifically, the heat exchange medium is sodium and potassium salts, and the capillaries are polytetrafluoroethylene fibers and aromatic fibers. The upper part of the heat pipe 7 extends into the upper cavity 8 and contacts with the cooling water supplied by the water inlet pipe 5, and the lower part of the heat pipe 7 extends into the lower cavity 9 and contacts with the exhaust gas supplied by the tee 4.

[0028] The benefits of this setting are:

[0029] 1. It can realize the separation and efficient collection of heat and acidic substances in acid-containing high-temperature exhaust gas.

[0030] 2. It can prevent the entry of acidic substances in acid-containing high-temperature exhaust gas, so that the steam formed by heating the cooling water is completely acid-free, obtaining acid-free steam, thereby extending the service life of the equipment (more than 15 years).

[0031] 3. It can prevent the mixing of cooling water into the condensed acid solution, thereby maintaining the concentration of the acid solution and facilitating subsequent use.

[0032] To further improve the heat exchange efficiency, the heat pipe also includes fins wrapped around the outer side of its upper portion. The fins include flat fins 10 and spiral fins 11. Compared with the flat fins 10, the spiral fins 11 are more conducive to the discharge of acid-free steam. Preferably, the spiral angle of the spiral fins 11 is 30-42 degrees. To avoid scaling, in this embodiment, the overall smoothness of the heat pipe 7 (including the fins) is not greater than 1.6 microns.

[0033] Due to the pressure difference between the preheater and the reactor, if an ordinary tee is used, the phenomenon of acid-containing high-temperature exhaust gas backflow is likely to occur. To solve this problem, the tee 4 in this embodiment adopts a Rafael tube structure. Specifically, the internal cavity of the tee 4 includes a horizontal cavity 12 and an inclined cavity 13 arranged from top to bottom. One end of the horizontal cavity 12 is connected to the reactor, and the other end is connected to the lower cavity 9. The upper end of the inclined cavity 13 is connected to the preheater, and the lower end is connected to the horizontal cavity 12. The two ends of the horizontal cavity 12 are large and the middle is small. It is divided into a high-pressure gas zone 14 at the inlet end, a lafayette throat zone 15 in the middle section, and a diffusion injection zone 16 at the outlet end. The angle of the diffusion injection zone 16 is 9-14 degrees. During production, a separate simulation calculation is required to determine whether the injection angle is appropriate. When the reactor introduces acid-containing high-temperature exhaust gas into the high-pressure gas zone, a vacuum zone 17 is formed in the diffusion injection zone 16 near the lafayette throat zone 15. There are three inclined cavities 13 to distinguish the low-temperature, medium-temperature and high-temperature preheaters. The lower ends of these three inclined cavities 13 are all connected to the vacuum zone 17.

[0034] In this embodiment, a valve (not shown in the figure) is connected to the acid liquid outlet 3. At the initial stage of use of the tail gas condenser, the valve is closed, so that the condensed acid liquid is gathered in the lower part of the tank body 1 (the acid liquid level immerses the entire diffusion injection area 16 or immerses a part of the diffusion injection area 16) to fully collect the heat in the acid liquid. At the same time, the diffusion injection area 16 extends along the tangential direction of the tank body 1, so that the acid-containing high-temperature exhaust gas ejected from the diffusion injection area 16 forms a circumferential airflow in the tank body 1, and drives the acid liquid condensed at the bottom of the tank body 1 to produce a circumferential flow, thereby enhancing the convective heat transfer coefficient and improving the heat exchange efficiency. During use, the valve is opened from time to time to discharge the acid liquid according to parameters such as the acid liquid level and air pressure in the tank body 1.

[0035] In order to further improve the quality of acid-free steam, in this embodiment, a shell and tube superheater 18 is further provided in the tank body 1. The shell and tube superheater 18 is located above the heat pipe 7. The inlet of the shell and tube superheater 18 is connected to the high-temperature preheater, and the outlet of the shell and tube superheater 18 is connected to the lower cavity 9. At the same time, a gas-liquid separator 19 is further provided in the tank body 1, and the gas-liquid separator 19 is docked at the steam outlet 2; the shell and tube superheater 18 is calculated according to the evaporation amount of the upper cavity, and its load and evaporation amount are matched. The length of the heat exchange tube of the shell and tube superheater 18 is controlled within the range of 800-1500mm, and the tube specifications are ⌀19X2, ⌀25X2, ⌀32X2, ⌀38X2, ⌀48X3, and ⌀57X3, which can improve the quality of steam.

[0036] In order to further improve the heat exchange efficiency and accelerate the generation of acid-free steam, in this embodiment, the water inlet pipe 5 is arranged close to the inner wall of the tank body 1. The water inlet pipe 5 is annular, and the end of the water inlet pipe 5 located in the tank body 1 is closed, and a plurality of water spray holes 20 are provided on the outer wall of the water inlet pipe 5 facing the heat pipe 7.

[0037] In this embodiment, the tank body 1 includes a cylindrical barrel 21, an elliptical head 22 connected to the top of the barrel 21 and a lower cone 23 connected to the bottom of the barrel 21. A steam outlet 2 is opened in the center of the elliptical head 22, the lower cone 23 is located below the tee 4, a skirt 24 is provided on the outer side of the lower cone 23, and an acid outlet 3 is opened in the bottom center of the lower cone 23; in order to facilitate the observation of the cooling water and acid liquid levels in the tank body 1, the barrel 21 is further provided with a first liquid level tube 25 and a second liquid level tube 26 extending up and down, and the two ends of the first liquid level tube 25 are connected to the upper cavity 8 for detecting the coolant level in the upper cavity 8. An overflow pipe 27 is connected to the middle of the first liquid level tube 25, and the end of the overflow pipe 27 away from the first liquid level tube 25 is connected to the water inlet pipe 5, and the two ends of the second liquid level tube 26 are connected to the lower cavity 9 for detecting the acid liquid level in the lower cavity 9.

[0038] In this embodiment, the sealing plate structure is manufactured as follows: first, a hole is drilled on the partition to form a tube plate, and then the heat pipe is inserted into the hole, and then the heat pipe is welded to the hole; for the heat pipe, a spiral fin is first wrapped around the outer side of the light pipe on the upper part of the heat pipe to allow the generated steam bubbles to flow out smoothly. After welding the spiral fins and the light pipe on the heat pipe, the overall polishing treatment is performed to reduce the overall smoothness of the heat pipe to 1.6 microns. The heat pipe with smooth finish has higher anti-scaling performance. When welding, the spiral angle of the spiral fin is adjusted to between 30-42 degrees, which can smoothly exhaust the air and allow the bubbles generated on the fin surface to be discharged smoothly. Compared with the traditional light pipe, its efficiency can be increased by 25-30%, which enhances the heat transfer effect. Specifically, the specifications of the heat pipe can be Etc., the materials are acid-resistant alloy steel pipes such as super duplex steel, monel alloy, nickel-based alloy, Hastelloy alloy, etc. After filling is completed, the two ends of the heat pipe are sealed with pipe caps and sealed with argon arc welding. The heat pipe can withstand a pressure of at least 30 kg.

[0039] This application adopts the split-chamber heat pipe technology to isolate the acid-containing high-temperature exhaust gas in the lower part of the tail gas condenser tank, so that the heat is transferred to the upper part of the tank through the heat conduction of the heat pipe to heat the clean cooling water, thereby forming acid-free steam, completely eliminating the problem of steam containing acid; This application adopts a tee with a Rafael tube structure, which can achieve step-by-step pressure reduction, and cooperates with the injection of the diffusion injection area and the siphon technology of the vacuum area to avoid the backflow and gas channeling phenomenon of high-pressure materials to the low-pressure side. There is no need to set components such as check valves on the low-pressure side, and the overall structure is simpler and more effective. At the same time, the tee is made by pressing, and the material can be selected from acid-resistant alloy steel pipes such as super duplex steel, monel alloy, nickel-based alloy, Hastelloy alloy, etc. The thickness is 4-8mm, which can avoid the uneven metal structure and poor toughness reserve of the welded tee, and the right-angle connection of the outer wall of the tee adopts a smooth transition structure, which can ensure that the stress distribution at each angle is smaller and less likely to be concentrated; the design of the water spray hole type water inlet pipe adopted in this application can make the cooling water supplied to the upper cavity of the tank body in a thin column and spray it to the upper end of the heat pipe at high speed, which can not only improve the heat transfer effect with the heat pipe, but also flush the surface of the heat pipe to avoid scaling; the design of the split-cavity heat pipe technology + Rafael tube structure tee + water spray hole type water inlet pipe can not only realize the separate collection of acid and heat to obtain acid-free steam, but also improve the collection efficiency and ensure the concentration of the collected acid.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tail gas condenser capable of providing acid-free steam, comprising a tank body, a steam outlet provided at the top of the tank body, an acid liquid outlet provided at the bottom of the tank body, a tee for supplying exhaust gas to the tank body, and a water inlet pipe for supplying cooling water to the tank body; characterized in that: A sealing plate structure is provided inside the tank body to isolate the exhaust gas and cooling water. The sealing plate structure includes a tube plate that spans the tank body and a plurality of independent heat pipes that are sealed and pass through the tube plate. The tube plate is sealed and connected to the inner wall of the tank body. Its height is higher than the tee and lower than the water inlet pipe, dividing the cavity in the tank body into an upper cavity connected to the water inlet pipe and a lower cavity connected to the tee. The heat pipe is a straight pipe that extends up and down and is closed at both ends. The interior of the heat pipe is filled with heat exchange medium and capillary. The upper part of the heat pipe extends into the upper cavity and contacts with the cooling water supplied by the water inlet pipe, and the lower part of the heat pipe extends into the lower cavity and contacts with the exhaust gas supplied by the tee.

2. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: The heat pipe further includes a spiral fin spirally wound on the outer side of the upper portion thereof, the spiral fin having a spiral angle of 30-42 degrees, and the overall smoothness of the heat pipe is no greater than 1.6 microns.

3. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: The heat exchange medium is sodium and potassium salt, and the capillary material is polytetrafluoroethylene fiber and aromatic fiber.

4. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: The internal cavity of the tee includes a horizontal cavity and an inclined cavity arranged from top to bottom. One end of the horizontal cavity is connected to the reactor, and the other end is connected to the lower cavity. The upper end of the inclined cavity is connected to the preheater, and the lower end is connected to the horizontal cavity.

5. The tail gas condenser capable of providing acid-free steam according to claim 4, characterized in that: The horizontal cavity is larger at both ends and smaller in the middle, dividing the horizontal cavity into a high-pressure gas zone at the inlet end, a lafayette throat zone in the middle section, and a diffusion injection zone at the outlet end. When the reactor introduces acid-containing high-temperature exhaust gas into the high-pressure gas zone, a vacuum zone is formed in the diffusion injection zone near the lafayette throat zone. There are multiple inclined cavities to distinguish and connect the low-temperature, medium-temperature and high-temperature preheaters, and the lower ends of multiple inclined cavities are connected to the vacuum zone.

6. The tail gas condenser capable of providing acid-free steam according to claim 5, characterized in that: The diffusion spray zone extends along the tangential direction of the tank body, so that the acid-containing high-temperature exhaust gas ejected from the diffusion spray zone forms a circumferential airflow in the tank body, and drives the acid liquid condensed at the bottom of the tank body to generate a circumferential flow, thereby enhancing the convective heat transfer coefficient.

7. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: A shell and tube superheater is further provided in the tank body. The shell and tube superheater is located above the heat pipe. The inlet of the shell and tube superheater is connected to the high-temperature preheater, and the outlet of the shell and tube superheater is connected to the lower cavity.

8. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: The water inlet pipe is arranged close to the inner wall of the tank body, and is semi-annular or annular. The end of the water inlet pipe located inside the tank body is closed, and a plurality of water spray holes are provided on the outer wall of the water inlet pipe facing the heat pipe.

9. The tail gas condenser capable of providing acid-free steam according to claim 1, characterized in that: The tank body includes a cylindrical barrel, an elliptical head connected to the top of the barrel and a lower cone connected to the bottom of the barrel. The steam outlet is opened at the center of the elliptical head. The lower cone is located below the tee. A skirt is provided on the outside of the lower cone. The acid outlet is opened at the bottom center of the lower cone.

10. The tail gas condenser capable of providing acid-free steam according to claim 9, characterized in that: The cylinder is provided with a first liquid level tube and a second liquid level tube extending up and down. The two ends of the first liquid level tube are connected to the upper cavity and are used to detect the coolant level in the upper cavity. The middle part of the first liquid level tube is connected to an overflow pipe, and the end of the overflow pipe away from the first liquid level tube is connected to the water inlet pipe. The two ends of the second liquid level tube are connected to the lower cavity and are used to detect the acid level in the lower cavity.

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