Isothermal reactor system

Abstract

The utility model provides an isothermal reactor system which comprises an isothermal reactor and a heat exchanger, the isothermal reactor comprises a shell pass and a tube pass, the isothermal reactor comprises a plurality of reaction units, and each reaction unit comprises an upper-layer air inlet area, a middle reaction area and a lower-layer exhaust area. The middle reaction area is provided with a plurality of reaction tubes which are regularly arranged, the upper end ports of the reaction tubes are fixed on the partition plate and are communicated with the upper-layer gas inlet area, and the lower end ports of the reaction tubes are fixed on the grid layer. According to the utility model, an isothermal reactor system and a heat exchanger structure are reasonably designed, process conditions are coordinated, SO2 oxidation under isothermal conditions is realized, the reaction temperature in the reactor is always kept in a continuous reaction temperature interval, the problem that the reaction temperature is continuously increased due to reaction heat release in the traditional process is avoided, the SO2 conversion rate is greatly improved, and the production cost is reduced. Catalyst bed layers are reduced, and the process is simplified, so that actual production requirements are met.

Description

Technical Field

[0001] The utility model belongs to the technical field of sulfuric acid production, and in particular relates to an isothermal reactor system. Background Art

[0002] At present, industrial sulfuric acid production equipment or industrial waste sulfuric acid incineration and regeneration equipment using sulfuric acid gas from refineries or oil and gas fields, low-temperature methanol-washed acid gas from coal chemical industry, smelting tail gas, and liquid sulfur as raw materials need to be equipped with a reactor for converting SO2 into SO3. The existing process usually uses an adiabatic reactor. In order to meet the SO2 conversion rate requirements, 2-3 layers of catalyst beds need to be set. The process gas containing sulfur dioxide and oxygen reacts through the first layer of catalyst bed, releasing heat, so that the temperature of the bed is close to thermodynamic equilibrium, causing the reaction to stop. The reaction conditions need to be changed, such as lowering the temperature, so that the reaction can continue. Therefore, a heat exchanger is set after the reactor bed to take away the reaction heat. After cooling, the process gas enters the next level of catalyst bed to continue the reaction. Since an adiabatic reactor is used, the conversion rate of each catalyst bed is not high. Therefore, after 2-3 layers of catalyst conversion, the total conversion rate of SO2 can reach about 98-99%. It is not very meaningful to increase the total conversion rate by simply increasing the number of catalyst beds. Usually, it is necessary to change the composition of the process gas and then set up a secondary reactor for catalytic conversion to obtain a high SO2 conversion rate; and to change the composition of the process gas, a condenser system needs to be set up for the "wet" process, and an absorption system needs to be set up for the "dry" process. This results in a cumbersome process and increased energy consumption and production costs.

[0003] To this end, it is necessary to further optimize the process methods and reactor systems for preparing sulfuric acid from sulfuric acid-containing gases such as refineries, oil and gas fields, and coal chemical low-temperature methanol washing, so as to increase the yield of single-layer or single reaction, simplify the process, and reduce energy consumption and costs. Utility Model Content

[0004] In order to solve the above problems, the utility model provides an isothermal reactor system for preparing sulfuric acid with sulfuric acid-containing gas and a method for preparing sulfuric acid using the system. In the utility model, the isothermal reactor is reasonably designed to transfer the reaction heat to the cooling medium, so that the temperature inside the reactor is constant, and the reaction gas is kept for isothermal reaction, thereby greatly improving the conversion rate of a single catalyst bed, which can reach 99.5%. The heat exchange of the isothermal reactor is continuously maintained by a heat exchange unit to achieve a stable reaction process. Compared with conventional adiabatic reactors, the isothermal reactor system of the utility model has a simpler process flow, smaller equipment size, less investment, and longer catalyst life at the same conversion rate for new projects; for renovation projects, it can increase production capacity and reduce the operating energy consumption of the device.

[0005] The utility model aims to provide an isothermal reactor system, which comprises an isothermal reactor and a heat exchanger.

[0006] The isothermal reactor comprises a shell side and a tube side. The process gas is introduced into the tube side of the isothermal reactor, and the cooling medium is introduced into the shell side.

[0007] The isothermal reactor comprises a plurality of reaction units, which are connected in series or in parallel. The reaction unit comprises an upper air inlet zone, a middle reaction zone and a lower exhaust zone.

[0008] The middle reaction zone is provided with a number of regularly arranged reaction tubes, the upper end ports of the reaction tubes are fixed on the partition plate and are connected with the upper air inlet zone. The lower end ports of the reaction tubes are fixed on the grid layer, and a support brick layer is provided close to the lower portion of the grid layer. The reaction tubes are filled with catalysts, and the process gas first enters the upper air inlet zone and then enters the reaction tubes. The process gas after the reaction with the catalyst passes through the grid layer and the support brick layer and enters the lower exhaust zone.

[0009] The isothermal reactor system provided by the utility model has the following beneficial effects:

[0010] (1) The isothermal reactor system provided in the utility model reasonably designs the isothermal reactor, uses an array of reaction tubes filled with catalysts to achieve single-bed catalytic oxidation of sulfur dioxide, reasonably optimizes process conditions, and uses shell-side heat exchange in real time to exchange the reaction heat out of the reactor, thereby reducing the reactor temperature and ensuring the continuous progress of the oxidation reaction.

[0011] (2) The isothermal reactor system provided by the utility model can replace the adiabatic reactor system used in traditional industrial sulfuric acid production or waste sulfuric acid regeneration, and can be used for new construction or renovation projects. The utility model uses an isothermal reactor and sets a single bed layer to meet a total reaction conversion rate of more than 99.5%, while conventional adiabatic reactors require two stages, and each stage of the reactor needs to be set up with 2-3 layers of catalyst beds. The reaction heat can be used to take heat from molten salt once to the heat exchange system to recover heat, making the heat exchange system simpler and the heat recovery efficiency higher.

[0012] (3) Compared with conventional adiabatic reactors, the isothermal reactor system of the utility model has a simpler process flow, smaller equipment size, less investment, and longer catalyst life for new projects at the same conversion rate; for renovation projects, it can increase production capacity and reduce operating energy consumption of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A process flow chart of an isothermal reactor system of the utility model is shown;

[0014] Figure 2 A schematic front view of the structure of an isothermal reactor 1 of the utility model is shown;

[0015] Figure 3A left view of an isothermal reactor 1 of the utility model is shown;

[0016] Figure 4 A schematic diagram showing the structure of a longitudinal baffle 29 in an upper baffle area 27 of an isothermal reactor 1 of the present invention;

[0017] Figure 5 The schematic diagram of the structure of the longitudinal baffle 29 in the lower baffle area 28 of an isothermal reactor 1 of the present invention is shown.

[0018] Description of Figure Numbers

[0019] 1-isothermal reactor;

[0020] 2-Heat exchanger;

[0021] 1011-upper air intake area;

[0022] 1012- middle reaction area;

[0023] 1013-lower exhaust area;

[0024] 1014-partition;

[0025] 11-Process gas inlet;

[0026] 12-process gas outlet;

[0027] 21- reaction tube;

[0028] 22- grid layer;

[0029] 23- supporting brick layer;

[0030] 24-shell side import;

[0031] 25-shell side outlet;

[0032] 26- transverse baffle;

[0033] 27-upper baffle area;

[0034] 28-lower baffle area;

[0035] 29- longitudinal baffle;

[0036] 2901-Exit on both sides;

[0037] 2902-Middle exit;

[0038] 2601- transverse baffle outlet;

[0039] 201- pump;

[0040] 202-heater;

[0041] 3- Cooler. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below through specific implementation modes, and the features and advantages of the present invention will become clearer and more explicit with these descriptions.

[0043] The utility model provides an isothermal reactor system, which comprises an isothermal reactor 1 and a heat exchanger 2. Figure 1 shown.

[0044] The isothermal reactor 1 comprises a shell side and a tube side. The process gas is introduced into the tube side of the isothermal reactor 1, and the cooling medium is introduced into the shell side.

[0045] The isothermal reactor system in the utility model is suitable for preparing sulfuric acid from various process gases, such as producing industrial sulfuric acid using sulfuric acid-containing gas from refineries or oil fields, low-temperature methanol-washed acid gas from coal chemical industry or liquid sulfur as raw materials. It can also be used for regenerating industrial waste sulfuric acid. There is no limit on the upper limit of SO2 concentration and production can be achieved.

[0046] The volume fraction of SO2 in the process gas is greater than 8%, preferably greater than 10%, and more preferably 12%-25%.

[0047] The cooling medium is a hot molten salt, such as a hot molten salt mixture of potassium nitrate, sodium nitrate and sodium nitrite.

[0048] The isothermal reactor 1 includes a plurality of reaction units, which are connected in series or in parallel. The reaction unit includes an upper air inlet zone 1011, a middle reaction zone 1012 and a lower exhaust zone 1013. A partition 1014 is provided between the upper air inlet zone 1011 and the middle reaction zone 1012; a grid layer 22 and a support brick layer 23 are provided between the middle reaction zone 1012 and the lower exhaust zone 1013. Figure 2 shown.

[0049] The upper gas inlet area 1011 is provided with a process gas inlet 11, and the lower gas exhaust area 1013 is provided with a process gas outlet 12. Figure 2 and Left View Figure 3 As shown, the process gas containing SO2 enters the upper gas inlet zone 1011 through the process gas inlet 11. A gas flow distributor is provided at the process gas inlet 11 to evenly disperse the gas flow. The temperature of the process gas is 370-440°C, preferably 390-430°C, and more preferably 410-420°C.

[0050] The middle reaction zone 1012 is provided with a number of regularly arranged reaction tubes 21, the upper end ports of the reaction tubes 21 are fixed on the partition 1014, and are connected to the upper gas inlet zone 1011, preferably arranged vertically. The ratio of the number of the reaction tubes 21 to the area of ​​the partition is (3000-5500) tubes: 30m 2 , preferably (3500-5000) roots: 30m 2 , more preferably (4000-4500) roots: 30m 2 The ratio of the sum of the end areas of the reaction tube 21 to the area of ​​the partition is (6-17):30, preferably (8-15):30, and more preferably (10-13):30. The lower end of the reaction tube 21 is fixed on the grid layer 22, and a support brick layer 23 is arranged close to the lower part of the grid layer 22. The reaction tube 21 is filled with a catalyst, and the process gas first enters the upper gas inlet area 1011 and then enters the reaction tube 21. The process gas after contacting and reacting with the catalyst passes through the grid layer 22 and the support brick layer 23 and enters the lower gas exhaust area 1013, and is discharged from the reaction unit through the process gas outlet 12.

[0051] The catalyst is one or more vanadium-based catalysts, such as BASF O4-110 and O4-111.

[0052] The upper air inlet zone 1011, the reaction tube 21 and the lower exhaust zone 1013 constitute the tube side, and the area between the reaction tube 21 and the shell of the middle reaction zone 1012 constitutes the shell side. The upper part of the side of the middle reaction zone 1012 is provided with a shell side inlet 24, and the lower part is provided with a shell side outlet 25. The cooling medium enters through the shell side inlet 24 and flows out through the shell side outlet 25. Preferably, the shell side inlet 24 and the shell side outlet 25 are arranged on the same side of the middle reaction zone 1012, so that the route of the cooling medium baffle flow in the shell side is the longest.

[0053] A transverse baffle 26 is disposed in the middle of the middle reaction zone 1012 to separate the shell side inlet 24 and the shell side outlet 25 into an upper baffle 27 and a lower baffle 28 of the middle reaction zone 1012, respectively. Figure 2 shown.

[0054] The upper baffle area 27 and the lower baffle area 28 are also provided with longitudinal baffles 29, respectively. Two adjacent longitudinal baffles 29 are provided with two side outlets 2901 or a middle outlet 2902, respectively, so that the cooling medium flows out from the two side outlets 2901 of the longitudinal baffle 29 and then flows out from the middle outlet 2902 of the next longitudinal baffle 29, forming a wave-shaped baffle to increase the heat transfer efficiency. Figure 4 and Figure 5 shown.

[0055] The last longitudinal baffle plate 29 of the upper baffle zone 27 is provided with outlets 2901 on both sides, so that the cooling medium flows out from the outlets 2901 on both sides of the longitudinal baffle plate 29 and then flows to the lower baffle zone 28 from the transverse baffle outlet 2601 in the middle of the transverse baffle plate 26. Figure 4 shown.

[0056] The width ratio of the two side outlets 2901 to the corresponding longitudinal baffle 29 is 3585:(250-370), preferably 3585:(270-350), more preferably 3585:(290-330); the width ratio of the middle outlet 2902 to the corresponding side longitudinal baffle 29 is (560-680):1800, preferably (580-660):1800, more preferably (600-640):1800. The area ratio of the transverse baffle outlet 2601 to the transverse baffle 26 is 1:(24-38), preferably 1:(26-36), more preferably 1:(28-34).

[0057] In the utility model, by reasonably designing the tube-side distribution and the shell-side molten salt deflection, the molten salt can be fully and timely heat exchanged with the middle reaction zone 1012, so that the reaction temperature of the middle reaction zone 1012 is always maintained at 430-490°C, preferably at 440-480°C, and more preferably at 450-470°C, to carry out constant temperature reaction, thereby improving the conversion rate of SO2.

[0058] The inlet and outlet of the heat exchanger 2 are respectively connected to the shell outlet 25 and the shell inlet 24 of the isothermal reactor 1 to realize the closed-loop circulation of the cooling medium. The cooling medium is a hot molten salt, and its temperature entering the isothermal reactor 1 is 250-300°C, preferably 260-290°C, more preferably 270-280°C, and the temperature flowing out of the isothermal reactor 1 is 400-450°C, preferably 410-440°C, more preferably 420-430°C. The heat exchange medium used to cool the hot molten salt in the heat exchanger 2 is saturated steam of 4-5MPag to ensure the temperature of the hot molten salt used to keep the isothermal reactor 1 constant.

[0059] A pump 201 is provided between the heat exchanger 2 and the shell inlet 24 of the isothermal reactor 1 to pressurize the molten salt, control the pressure and flow rate of the molten salt, and thus control the reaction temperature in the isothermal reactor 1. The pump 201 increases the pressure to 4-9 barg, preferably 5-8 barg, and more preferably 6-7 barg.

[0060] Preferably, a heater 202 is also provided between the heat exchanger 2 and the shell inlet 24 of the isothermal reactor 1 to meet the demand for heating the cooling medium molten salt when the system is started. The heater 202 is heated by a line fuel gas burner to make the temperature of the molten salt reach 250-300°C, preferably 260-290°C, and more preferably 270-280°C.

[0061] The isothermal reactor system is also provided with a cooler 3, whose air inlet is connected to the process gas outlet 12. It is used to cool and recover the heat of the process gas containing SO3 coming out of the isothermal reactor 1. The temperature of the process gas containing SO3 coming out of the isothermal reactor 1 is 430-490°C, preferably 440-480°C, more preferably 450-470°C, and the temperature of the process gas coming out of the cooler 3 is 260-310°C, preferably 270-300°C, more preferably 280-290°C. The cooling medium of the cooler 3 is hot molten salt, and its temperature is 260-285°C, preferably 270-275°C.

[0062] The utility model also provides a sulfuric acid production method, which is carried out by utilizing the isothermal reactor system.

[0063] In the sulfuric acid production method, the raw materials are sulfuric acid gas from refineries or oil fields, low-temperature methanol-washed acid gas from coal chemical industry, smelting tail gas, waste sulfuric acid process gas or liquid sulfur.

[0064] The isothermal reactor system provided in the utility model reasonably designs the isothermal reactor and the heat exchange structure, coordinates the process conditions, realizes the conversion of SO2 to SO3 under isothermal conditions, keeps the reaction temperature in the reactor in the continuous reaction temperature range, avoids the problem of continuous increase in reaction temperature due to reaction exotherm in the traditional process, greatly improves the SO2 conversion rate, reduces the catalyst bed, simplifies the process, and meets the needs of actual production.

[0065] Example

[0066] Example 1

[0067] Sulfuric acid is produced using smelting tail gas as process gas, with a volume concentration of SO2 of 15%.

[0068] The heater 202 (molten salt electric heater of Wuxi Borui Oak Electric Co., Ltd.) was started to heat the hot molten salt to 275° C. The above process gas at 415° C. was introduced into the isothermal reactor system for reaction. The isothermal reactor system is specifically as follows Figure 1 As shown. The process gas inlet 11 of the isothermal reactor 1 is equipped with a distributor (commercially available), and the process gas is 18000Nm 3 / h flow rate, enters the reaction tube 21 through the upper air inlet area 1011, contacts and reacts with the catalyst, passes through the grid layer 22 and the supporting brick layer 23, enters the lower exhaust area 1013, and is discharged through the process gas outlet 12. The process gas temperature here is 460°C, enters the cooler 3 to be cooled to 285°C, and enters the subsequent process.

[0069] The isothermal reactor 1 has 4232 reaction tubes 21 regularly distributed, the diameter of the reaction tube 21 is φ60 mm, the length of the partition 1014 is 7340 mm, and the width is 4215 mm. The catalyst is BASF O4-111, and the total filling volume is 17.6 m 3 . In the shell side, a mixture of potassium nitrate, sodium nitrate and sodium nitrite with a mass ratio of 53:7:40 is used as the molten salt, with a total mass of 130t. The temperature of the molten salt entering the shell side is 275°C, and the circulating shell side temperature is 430°C. Three longitudinal baffles 29 are respectively arranged in the upper baffle area 27 and the lower baffle area 28, which divide the upper baffle area 27 and the lower baffle area 28 into four equal spaces, wherein the width of the two side outlets 2901 and the width of the corresponding longitudinal baffle 29 are about 3585:315, and the width of the middle outlet 2902 and the width of the corresponding side longitudinal baffle 29 are about 630:1792.5. The area ratio of the transverse baffle outlet 2601 to the transverse baffle 36 is about 1:32.7.

[0070] The 430°C molten salt releases heat through heat exchanger 2 (BKU type heat exchanger, pipe length 6m), and the temperature is reduced to 275°C. Heat exchanger 2 uses 4.3MPag saturated steam to cool the molten salt; the molten salt is then pressurized to 7barg by pump 201 and returned to the isothermal reactor 1.

[0071] According to the test, the molar conversion rate of sulfur dioxide is 99.8%.

[0072] The present invention is described in detail above in combination with specific implementations and / or exemplary examples and drawings, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, the technical solution of the present invention and its implementation methods may be subjected to various equivalent substitutions, modifications or improvements, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. An isothermal reactor system, comprising an isothermal reactor (1) and a heat exchanger (2), characterized in that: The isothermal reactor (1) comprises a shell side and a tube side, The isothermal reactor (1) comprises a plurality of reaction units, each of which comprises an upper gas inlet zone (1011), a middle reaction zone (1012) and a lower gas exhaust zone (1013). The middle reaction zone (1012) is provided with a plurality of regularly arranged reaction tubes (21), the upper ends of the reaction tubes (21) are fixed on the partition plate (1014) and are connected to the upper gas inlet zone (1011). The lower port of the reaction tube (21) is fixed on the grid layer (22).

2. The isothermal reactor system according to claim 1, characterized in that A supporting brick layer (23) is arranged closely below the grid layer (22).

3. The isothermal reactor system according to claim 1, characterized in that The upper air inlet zone (1011), the reaction tube (21) and the lower exhaust zone (1013) constitute a tube side, and the area between the reaction tube (21) and the shell of the middle reaction zone (1012) constitutes a shell side. The upper air intake area (1011) is provided with a process gas inlet (11), and the lower air exhaust area (1013) is provided with a process gas outlet (12).

4. The isothermal reactor system according to claim 1, characterized in that A shell-side inlet (24) is arranged at the upper part of the side of the middle reaction zone (1012), and a shell-side outlet (25) is arranged at the lower part; a transverse baffle (26) is arranged in the middle of the middle reaction zone (1012) to separate the shell-side inlet (24) and the shell-side outlet (25) into an upper baffle area (27) and a lower baffle area (28) of the middle reaction zone (1012), respectively.

5. The isothermal reactor system according to claim 4, characterized in that The upper baffle area (27) and the lower baffle area (28) are also provided with longitudinal baffles (29) respectively, and two adjacent longitudinal baffles (29) are provided with two side outlets (2901) or a middle outlet (2902) respectively.

6. The isothermal reactor system according to claim 4, characterized in that The last longitudinal baffle plate (29) of the upper baffle zone (27) is provided with two side outlets (2901), so that the cooling medium flows out from the two side outlets (2901) of the longitudinal baffle plate (29) and then flows to the lower baffle zone (28) from the transverse baffle plate outlet (2601) in the middle of the transverse baffle plate (26).

7. The isothermal reactor system according to claim 6, characterized in that The width ratio of the two side outlets (2901) to the corresponding longitudinal baffle (29) is 3585:(250-370), the width ratio of the middle outlet (2902) to the corresponding side longitudinal baffle (29) is (560-680):1800; the area ratio of the transverse baffle outlet (2601) to the transverse baffle (26) is 1:(24-38).

8. The isothermal reactor system according to claim 4, characterized in that The inlet and outlet of the heat exchanger (2) are respectively connected to the shell side outlet (25) and the shell side inlet (24) of the isothermal reactor (1), so as to realize the closed-loop circulation of the cooling medium.

9. The isothermal reactor system according to claim 4, characterized in that: A pump (201) is arranged between the heat exchanger (2) and the shell side inlet (24) of the isothermal reactor (1).

10. The isothermal reactor system according to claim 1, characterized in that The isothermal reactor system is also provided with a cooler (3), the air inlet of which is connected to the process gas outlet (12).

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