Composite absorption tower and gas treatment system and method

Abstract

The invention discloses a composite absorption tower and a gas treatment system and method. The process strengthening unit and the pressure energy recovery unit are arranged below the conventional absorption tower, the pressure energy of the pressurized fluid is fully utilized, and the pressurized fluid impacts the power impeller and pushes the impeller to rotate, so that the rotor assembly which is coaxially mounted is driven to rotate, and a strong centrifugal field is provided for the process strengthening reaction unit; the gas-liquid two-phase mass transfer process is greatly enhanced, and the gas absorption effect is promoted. The energy of the recovery system is used for strengthening the gas-liquid process, the gas absorption and purification effect is improved, meanwhile, the use amount of an absorption solvent is reduced, the regeneration load and the energy consumption of a circulating system are reduced, and it is ensured that the device operates safely and stably for a long period, and gas purification treatment is achieved efficiently at low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of process intensification and relates to a composite absorption tower, in particular to an energy recovery type composite absorption tower, a gas processing system and a method. Background Art

[0002] In the process of petrochemical production and natural gas processing, there are many gas treatments under medium and high pressure conditions, such as desulfurization and decarbonization in natural gas purification, and the process of removing acidic components such as hydrogen sulfide and carbon dioxide from catalytic / coking dry gas, circulating hydrogen, and hydrogenation low-fraction gas in refining enterprises. At present, the above processes generally adopt mature alcohol amine absorption process, that is, amine liquid "absorption-regeneration" complete set technology, and the absorbent is mainly alkaline aqueous solution such as DEA, MEA, MDEA, DEPA, etc. The typical absorption and regeneration process flow is that the raw gas enters from the bottom of the absorption tower, and contacts with the solution flowing down from the top of the tower in the packing layer in reverse, the acid gas in the gas phase is absorbed by the absorbent, and the tail gas after absorption is discharged from the top of the tower, and the rich liquid after absorbing the acid gas enters the regeneration tower. The rich liquid is thermally regenerated in the regeneration tower, releasing the acid gas, and is discharged from the top of the regeneration tower. The rich liquid is regenerated into lean liquid and circulated back to the absorption tower after cooling.

[0003] At present, the following problems are common in the amine liquid absorption and regeneration process. First, the above absorption process generally adopts tower equipment, that is, it is carried out in a packed tower / plate tower. The traditional absorption tower has the disadvantages of poor mass transfer effect, uneven gas-liquid flow, high resistance, easy clogging of fillers and unstable operation. In addition, due to the impurities such as light hydrocarbon droplets and rust entrained in the gas, the absorption liquid will have serious foaming phenomenon, which seriously affects the long-term, safe and stable operation of the desulfurization device. At the same time, due to the low desulfurization efficiency of the absorption tower, the content of acidic components in the rich liquid is far lower than the equilibrium value. Therefore, in order to ensure the treatment effect, the amount of amine liquid is often large, the regeneration load is large, and the energy consumption is high. Therefore, the development of high-efficiency absorption equipment and treatment processes, while ensuring the absorption and purification effect, reduces the amount of solvent, reduces the regeneration load and the energy consumption of the circulation system, and improves the foaming phenomenon of the solvent absorption system, is of great significance for improving the treatment effect of such gases and saving energy and reducing consumption.

[0004] Patent CN112159695A discloses an energy-saving natural gas MDEA decarbonization system and method. The thermal grade of the analytical gas output from the top of the regeneration tower is improved by pressurizing the analytical gas, which is used to heat the rich amine liquid entering the regeneration tower, so that the low-grade heat is reasonably recycled. At the same time, the analytical gas is cooled and then separated into gases, and the liquid is returned to the regeneration tower. There is no need to set up an additional regeneration tower top cooler, thereby reducing the amount of refrigerant and energy consumption. However, this technology requires the addition of analytical gas compressor equipment, which increases power consumption. In addition, traditional tower equipment still has problems such as low mass transfer efficiency, low absorption liquid concentration, large absorption liquid consumption, and easy foaming of the absorption liquid.

[0005] As a highly efficient process intensification equipment, the ultra-gravity reactor can achieve mass transfer process intensification through centrifugal force. Compared with the traditional mass transfer method, the mass transfer efficiency can be improved by an order of magnitude. It has the advantages of high efficiency, small equipment size, easy operation and convenient equipment maintenance. At present, ultra-gravity technology has been applied in engineering in the fields of selective H2S removal, flue gas desulfurization and dust removal, nano-powder preparation, extraction, and distillation. In addition to its efficient purification effect, this technology can also eliminate the foaming of amine liquid when used in the amine liquid absorption system. It can increase the concentration of amine liquid to a certain extent, thereby reducing the circulation volume of amine liquid, greatly reducing the regeneration load of amine liquid and the energy consumption of the circulation system. However, the drive of the ultra-gravity reactor bed (rotor) of this technology requires a motor to provide power, which increases the energy consumption problem.

[0006] Patent CN105385479A discloses a super-gravity desulfurization and decarbonization device that integrates the hydrate method and the membrane method. By combining the hydrate method with the membrane separation method and introducing super-gravity technology on this basis, the natural gas is deeply desulfurized and deacidified, which greatly improves the removal rate of acid gases such as H2S and CO2 in the natural gas. The upper part of the device is a super-gravity membrane separation unit, and the lower part of the device is a stirred hydrate reactor. The overall structure is complex, and the rotating parts of the super-gravity steering mechanism and the magnetic stirring of the stirred hydrate reactor both need to be driven by electric motors, which increases power consumption. Patents such as CN104826468A, CN104826469A, CN104826463A, CN104826466A, CN104826465A, and CN104826560A use a rotating bed reactor as a gas-liquid reactor to treat acid gas and produce NaHS products, which can achieve the dual goals of acid gas purification and pollutant resource utilization. However, the energy consumption of the rotating bed reactor operating motor is not considered during the treatment process. Summary of the invention

[0007] The present invention provides a composite absorption tower, a gas treatment system and a method. The composite absorption tower recovers system energy for the enhancement of the gas-liquid process, improves the gas absorption and purification effect, and reduces the amount of absorption solvent, thereby reducing the regeneration load and the energy consumption of the circulation system, ensuring the long-term, safe and stable operation of the device, and realizing gas purification treatment with high efficiency and low cost.

[0008] To achieve the above objectives, the first aspect of the present invention provides a composite absorption tower.

[0009] The composite absorption tower comprises a tower body, a first baffle, a second baffle, a tower absorption unit, a process intensification unit and an energy recovery unit; the first baffle and the second baffle are arranged inside the tower body, and the tower body is divided into three parts from top to bottom, namely, the tower absorption unit, the process intensification unit and the energy recovery unit; The tower absorption unit comprises a gas outlet, a demister, a first liquid inlet, a liquid distributor, an absorption tower section, a liquid collecting tower plate and a liquid collecting tray; The process intensification unit includes an air inlet, a first liquid discharge port, a liquid redistributor, a rotor assembly and a drive shaft; The pressure energy recovery unit includes a second liquid inlet, a second liquid outlet, a power impeller and a rotating shaft.

[0010] Furthermore, in the above-mentioned composite absorption tower, the driving shaft of the process intensification unit and the rotating shaft of the pressure energy recovery unit are coaxially connected through the second partition.

[0011] Furthermore, in the above-mentioned composite absorption tower, the first liquid discharge port and the second liquid inlet are connected through a pipeline.

[0012] Furthermore, in the above-mentioned composite absorption tower, the gas outlet of the tower absorption unit is arranged at the top of the tower body, the demister is arranged below the gas outlet, the first liquid inlet and the liquid distributor are arranged below the demister, the liquid distributor inlet is connected to the first liquid inlet, the absorption tower section is arranged below the liquid distributor, and the liquid collecting tower plate and the liquid collecting tray are arranged below the absorption tower section.

[0013] Furthermore, in the above-mentioned composite absorption tower, the absorption tower section is in the form of conventional fillers or tower plates.

[0014] Furthermore, in the above-mentioned composite absorption tower, the liquid collecting tower plate is a tower plate with an air riser hole. The air riser hole is not limited in form and can be a bubble cap, a float valve or other forms to ensure that the gas can pass smoothly. The center of the liquid collecting tower plate is a hollow structure, and an overflow weir is provided on the hollow edge. The lower edge of the hollow in the middle of the liquid collecting tower plate is connected to the upper edge of the liquid collecting tray.

[0015] Furthermore, in the above-mentioned composite absorption tower, the air inlet of the process intensification unit is arranged in the middle position of the tower body of this unit, the center of the inlet is radially horizontal with the rotor assembly, the first liquid discharge port is arranged at the lower position of the tower body of this unit, the rotor assembly is arranged in the middle of the tower body of this unit, the liquid redistributor is vertically arranged at the center position of the rotor assembly, and the upper end of the liquid redistributor is connected to the lower end of the liquid collecting tray.

[0016] Furthermore, in the above-mentioned composite absorption tower, the liquid accumulation tray is connected to the upper end of the liquid redistributor through the first partition plate, and a gas phase channel is left between the liquid accumulation tray and the first partition plate.

[0017] Furthermore, in the above-mentioned composite absorption tower, the rotor structure of the rotor assembly can be a packing type, a disc type, a spiral type, a baffle type or a composite type, and the rotor assembly is installed on a driving shaft.

[0018] Furthermore, in the above-mentioned composite absorption tower, the second liquid inlet of the pressure energy recovery unit is arranged on the side of the tower body of this unit, the center of the inlet is radially horizontal with the power impeller assembly, and the second liquid discharge port is located at the lower part or bottom of the tower body.

[0019] Furthermore, in the above composite absorption tower, the power impeller of the pressure energy recovery unit may be a single-stage or multi-stage impeller, and the power impellers are evenly arranged along the circumference and mounted on the rotating shaft.

[0020] Furthermore, in the above-mentioned composite absorption tower, the rotor assembly rotates following the driving shaft, the driving shaft rotates following the rotating shaft, the rotating shaft is driven by a power impeller, and the strong centrifugal force field generated by the rotation of the rotor is used to enhance the gas-liquid mass transfer process.

[0021] Furthermore, in the composite absorption tower, sealing components are arranged between the rotor assembly and the reactor shell, and between the rotating shaft and the partition plate to ensure that there is no leakage between the mutual areas.

[0022] The second aspect of the present invention provides a gas processing system, which contains the composite absorption tower described above.

[0023] A gas processing system, the system comprising a composite absorption tower, a flash tank, a lean and rich liquid heat exchanger, a regeneration tower, a lean liquid pump, a lean liquid cooler and a filtration system; wherein, The gas inlet of the composite absorption tower is connected to the raw gas pipeline, the gas outlet of the composite absorption tower is connected to the external gas pipeline, the first liquid inlet of the composite absorption tower is connected to the filter outlet, and the second liquid outlet of the composite absorption tower is connected to the liquid inlet of the flash tank; The liquid outlet of the flash tank is connected to the liquid inlet of the regeneration tower via a lean-rich liquid heat exchanger; The gas phase outlet of the regeneration tower is connected to the regeneration gas pipeline, and the liquid phase outlet of the regeneration tower is connected to the inlet of the lean liquid cooler after passing through the lean liquid pump and the lean-rich liquid heat exchanger in sequence; The lean liquid cooler outlet is connected to the filter system inlet.

[0024] Furthermore, the lean-rich liquid heat exchanger is a liquid-liquid heat exchanger, and the form of the heat exchanger is not limited.

[0025] Furthermore, a condenser is provided at the top of the regeneration tower, and a reboiler is provided at the bottom of the tower.

[0026] Furthermore, the first liquid discharge port of the composite absorption tower process intensification unit is connected to the second liquid inlet of the pressure energy recovery unit.

[0027] According to a third aspect of the present invention, the present invention provides a gas processing method, wherein the above-mentioned gas processing system is applied.

[0028] Specifically, the gas processing method comprises the following steps: (1) The gas to be treated first enters the process intensification unit of the composite absorption tower. The gas contacts the lean absorption liquid from the liquid redistributor in the rotor assembly area, undergoes the gas-liquid two-phase mass transfer intensification process and completes the initial absorption of the gas. The treated gas rises to the liquid collecting tower plate through the gas phase channel between the liquid collecting plate and the first partition plate, and then passes through the tower absorption unit of the composite tower from bottom to top through the gas rising holes of the liquid collecting tower plate. In this area, the gas is further absorbed and treated by the lean amine absorption liquid. The lean absorption liquid enters from the liquid inlet and passes through the liquid distributor, absorption tower section, liquid collecting plate, liquid redistributor and rotor assembly from top to bottom. After absorbing the components to be treated, it becomes rich absorption liquid and is discharged from the first liquid discharge port of the process intensification unit. (2) The rich absorbent discharged in step (1) enters the pressure energy recovery unit of the composite absorber, and the pressure energy of the rich absorbent is converted into kinetic energy. The pressurized liquid impacts the power impeller and drives the impeller to rotate, thereby driving the coaxially mounted rotor assembly to rotate. The depressurized fluid enters the flash tank from the second liquid discharge port of the pressure energy recovery unit; (3) The rich absorbent entering the flash tank in step (2) flashes off the dissolved hydrocarbons and then passes through the lean-rich liquid heat exchanger to be heated and enter the regeneration tower. In the regeneration tower, the rich absorbent is heated and decomposed to release the absorbed components to become lean absorbent, completing the regeneration of the absorbent. The high-concentration component gas released by the regeneration is subsequently treated. The regenerated lean absorbent is pressurized by a lean liquid pump, cooled by a lean-rich liquid heat exchanger, cooled by a lean liquid cooler, and filtered by a filtration system before returning to the composite absorber for recycling.

[0029] Furthermore, the gas to be treated in step (1) may be natural gas, liquefied gas, dry gas, low-fraction gas or circulating hydrogen for the purpose of removing acidic components such as H2S and CO2, or may be natural gas or other gas for the purpose of removing moisture, and the components to be treated are H2S, CO2 and H2O respectively.

[0030] Furthermore, the operating pressure of the composite absorption tower in step (1) is 0.3-20 MPa, and the operating temperature can be determined according to the specific treatment system.

[0031] Furthermore, the rotation speed of the rotor assembly in step (1) is 50 to 5000 rpm, preferably 200 to 2000 rpm.

[0032] Furthermore, the operating pressure of the regeneration tower in step (3) is 0.1-15 MPa, which is lower than the operating pressure of the process intensification reactor, and the operating pressure difference is 0.2-20 MPa, preferably 0.2-10 MPa; the operating temperature can be determined and adjusted according to the specific treatment system.

[0033] The gas treatment method of the present invention can be used in absorption-regeneration gas treatment fields with certain pressure drop conditions such as gas desulfurization, gas decarbonization, natural gas absorption dehydration, circulating hydrogen desulfurization and selective dehydrogen sulfide, such as amine liquid desulfurization, amine liquid decarbonization, MDEA selective dehydrogen sulfide, natural gas glycol dehydration and other processes.

[0034] Compared with the prior art, the present invention has the following beneficial effects: 1. A process intensification unit and a pressure energy recovery unit are arranged below the conventional absorption tower to fully utilize the pressure energy of the pressurized fluid. The pressurized liquid impacts the power impeller and drives the impeller to rotate, thereby driving the coaxially installed rotor assembly to rotate, providing a powerful centrifugal field for the process intensification reaction unit, greatly enhancing the gas-liquid two-phase mass transfer process and promoting the gas absorption effect.

[0035] 2. Compared with the existing tower equipment, the process intensification unit of the composite absorption tower of the present invention greatly enhances the gas-liquid mass transfer process, which is equivalent to adding a pre-absorption section before the conventional absorption tower treatment, adding a centrifugal field to enhance the absorption process, reducing the load of the absorption tower, greatly reducing the volume of the absorption tower equipment, and saving infrastructure and equipment investment.

[0036] 3. The present invention fully recovers the pressure energy of the pressurized rich absorption liquid before depressurization and regeneration and uses it as energy to drive the rotor assembly to enhance the absorption process. This not only makes the composite absorption tower have the advantages of supergravity equipment, but also solves the motor energy consumption problem of the supergravity reactor by utilizing the system pressure energy, thus realizing gas treatment with high efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of a composite absorption tower according to the present invention.

[0038] In the figure, 1-tower body, 2-first baffle, 3-second baffle, 4-tower absorption unit, 5-process intensification unit, 6-energy recovery unit; 7-gas outlet, 8-demister, 9-first liquid inlet, 10-liquid distributor, 11-absorption tower section, 12-liquid collecting tower plate, 13-liquid collecting tray, 14-gas inlet, 15-first liquid discharge port, 16-liquid redistributor, 17-rotor assembly, 18-drive shaft, 19-second liquid inlet, 20-second liquid discharge port, 21-power impeller, 22-rotating shaft, 23-air lifting hole, 24-overflow weir.

[0039] Figure 2 This is a schematic diagram of a gas processing system according to the present invention.

[0040] In the figure, 51-raw gas pipeline, 52-composite absorption tower, 53-exhaust gas pipeline, 54-filter, 55-flash tank, 56-rich absorption liquid pipeline, 57-lean and rich liquid heat exchanger, 58-regeneration tower, 59-regeneration gas pipeline, 60-lean liquid pump, 61-lean absorption liquid pipeline, 62-lean liquid cooler, 63-flash gas pipeline. DETAILED DESCRIPTION

[0041] The composite absorption tower, gas treatment system and method of the present invention are described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited thereto. Example 1

[0042] This embodiment describes a composite absorption tower of the present invention in detail. Figure 1 As shown, a composite absorption tower structure of the present invention is as follows: The composite absorption tower includes a tower body 1, a first baffle 2, a second baffle 3, a tower absorption unit 4, a process intensification unit 5 and an energy recovery unit 6; the first baffle 2 and the second baffle 3 are arranged inside the tower body 1, and the tower body is divided into three parts from top to bottom, namely the tower absorption unit 4, the process intensification unit 5 and the energy recovery unit 6; the tower absorption unit 4 includes an air outlet 7, a demister 8, a first liquid inlet 9, a liquid distributor 10, an absorption tower section 11, a liquid collecting tower plate 12 and a liquid collecting tray 13; the process intensification unit 5 includes an air inlet 14, a first liquid discharge port 15, a liquid redistributor 16, a rotor assembly 17 and a drive shaft 18; the energy recovery unit 6 includes a second liquid inlet 19, a second liquid discharge port 20, a power impeller 21 and a rotating shaft 22. The driving shaft 18 of the process intensification unit 5 is coaxially connected with the rotating shaft 22 of the energy recovery unit 6 through the second partition plate 3; the first liquid discharge port 15 is connected with the second liquid inlet 19 through a pipeline; the gas outlet 7 of the tower absorption unit 4 is arranged at the top of the tower body 1, the demister 8 is arranged below the gas outlet 7, the first liquid inlet 9 and the liquid distributor 10 are arranged below the demister 8, the inlet of the liquid distributor 10 is connected with the first liquid inlet 9, the absorption tower section 11 is arranged below the liquid distributor 10, and the liquid collecting tower plate 12 and the liquid collecting tray 13 are arranged below the absorption tower section 11; the liquid collecting tower plate 12 in the composite absorption tower is a tower plate with an air lifting hole 23, the center of the liquid collecting tower plate 12 is a hollow structure, and an overflow weir 24 is arranged on the hollow edge, and the lower edge of the middle hollow is connected to the upper edge of the liquid collecting tray 13; the gas inlet 14 of the process intensification unit 5 It is arranged in the middle position of this unit tower body, and the center of the inlet is radially horizontal with the rotor assembly 17. The first liquid discharge port 15 is arranged at the lower position of this unit tower body, and the rotor assembly 17 is arranged in the middle of this unit tower body. The liquid redistributor 16 is vertically arranged at the center position of the rotor assembly 17, and the upper end of the liquid redistributor 16 is connected with the lower end of the liquid collecting plate 13; the liquid collecting plate 13 is connected with the upper end of the liquid redistributor 16 through the first partition plate 2, and a gas phase channel is left between the liquid collection plate 13 and the first partition plate 2; the rotor assembly 17 is installed on the drive shaft 18; the second liquid inlet 19 of the pressure energy recovery unit 5 is arranged on the side of the unit tower body, and the center of the inlet is radially horizontal with the power impeller 21 assembly, and the second liquid discharge port 20 is located at the lower part or bottom of the tower body; the power impeller 21 of the energy recovery unit 6 is evenly arranged along the circumference and installed on the rotating shaft 22. When the composite absorption tower is working, the rotor assembly 17 rotates following the driving shaft 18, and the driving shaft 18 rotates following the rotating shaft 22. The rotating shaft 22 is driven by the power impeller 21, and the strong centrifugal force field generated by the rotation of the rotor is used to enhance the gas-liquid mass transfer process. Example 2

[0043] This embodiment describes a gas processing system of the present invention in detail.

[0044] like Figure 2 As shown, the present invention provides a gas processing system, which contains the composite absorption tower mentioned above. The system includes a composite absorption tower 52, a flash tank 55, a lean-rich liquid heat exchanger 57, a regeneration tower 58, a lean liquid pump 60, a lean liquid cooler 62 and a filtering system 54; the gas inlet of the composite absorption tower 52 is connected to the raw gas pipeline 51, the gas outlet of the composite absorption tower 52 is connected to the external exhaust gas pipeline 53, the first liquid inlet 9 of the composite absorption tower 52 is connected to the outlet of the filter 54, and the second liquid outlet 20 of the composite absorption tower is connected to the liquid inlet of the flash tank 55; the liquid outlet of the flash tank 55 is connected to the liquid inlet of the regeneration tower 58 through the lean-rich liquid heat exchanger 57; the gas phase outlet of the regeneration tower 58 is connected to the regeneration gas pipeline 59, and the liquid phase outlet of the regeneration tower 58 is connected to the inlet of the lean liquid cooler 62 after passing through the lean liquid pump 60 and the lean-rich liquid heat exchanger 57 in sequence; the outlet of the lean liquid cooler 62 is connected to the inlet of the filtering system 54; the first liquid discharge port 15 of the process intensification unit 5 of the composite absorption tower 52 is connected to the second liquid inlet 19 of the pressure energy recovery unit 6. Example 3

[0045] This embodiment describes the gas treatment method of the present invention in detail. Figure 1-2 The working process of a gas treatment system and method provided by the present invention is as follows: The gas to be treated first enters the process intensification unit 5 of the composite absorption tower 52 through the air inlet pipeline 51. The gas contacts the lean absorption liquid from the liquid redistributor 16 in the rotor assembly 17 area, performs the gas-liquid two-phase mass transfer intensification process and completes the initial absorption of the gas. The treated gas rises to the liquid collecting tower plate 12 through the gas phase channel between the liquid collecting plate 13 and the first partition plate 2, and then passes through the tower absorption unit 4 of the composite tower from bottom to top through the gas rising holes 23 of the liquid collecting tower plate 12. In this area, the gas is further absorbed and treated by the lean amine absorption liquid. The lean absorption liquid enters from the liquid inlet 9 and passes through the liquid distributor 10, the absorption tower section 11, the liquid collecting plate 13, the liquid redistributor 16 and the rotor assembly 17 from top to bottom. After absorbing the components to be treated, it becomes a rich absorption liquid and is discharged from the first liquid discharge port 15 of the process intensification unit 5. The discharged rich absorption liquid The collected liquid enters the pressure energy recovery unit 6 of the composite absorption tower 52, and the pressure energy of the rich absorption liquid is converted into kinetic energy. The pressurized liquid impacts the power impeller 21 and drives the impeller to rotate, thereby driving the coaxially installed rotor assembly 17 to rotate, and the depressurized fluid enters the flash tank 55 from the second liquid discharge port 20 of the pressure energy recovery unit 6; the rich absorption liquid entering the flash tank 55 flashes out the dissolved hydrocarbons and is heated by the lean-rich liquid heat exchanger 57 to enter the regeneration tower 58, in the regeneration tower 58, the rich absorption liquid is heated and decomposed to release the absorbed components to become lean absorption liquid, completing the regeneration of the absorption liquid, and the high-concentration component gas released by the regeneration is subsequently processed, and the regenerated lean absorption liquid is pressurized by the lean liquid pump 60, cooled by the lean-rich liquid heat exchanger 57, cooled by the lean liquid cooler 62, and filtered by the filtration system 54, and then returned to the composite absorption tower 52 for recycling. Example 4

[0046] This embodiment provides a specific application example of a gas processing system of the present invention.

[0047] use Figure 1 The present invention provides a composite absorption tower, and uses Figure 2A gas processing system shown is used to decarbonize natural gas from a gas field. The CO2 concentration in the natural gas is about 8% (V). A mixed amine absorption liquid of MDEA35%+DEA10%+H2O55% (mass concentration) is used for treatment. The absorption pressure is 8 Mpa, the absorption temperature is 45°C, the regeneration pressure is 0.8 Mpa, and the regeneration temperature is 130°C. The carbon-containing natural gas first enters the process intensification unit 5 of the composite absorption tower 52. The gas contacts the lean amine absorption liquid from the liquid redistributor 16 in the rotor assembly 17 area, and performs an intensified process of gas-liquid two-phase mass transfer to complete the initial absorption of CO2 gas. The treated natural gas rises through the liquid collecting tower plate 12 and passes through the tower absorption unit 4 of the composite tower. In this area, the gas is further absorbed and treated by the lean amine absorption liquid, and the CO2 concentration in the treated natural gas can be less than 0.5% (V). The lean absorption liquid passes through the liquid distributor 10, the absorption tower section 11, the liquid collecting plate 13, the liquid redistributor 16 and the rotor assembly 17 from top to bottom. After absorbing the CO2 gas, it becomes a rich absorption liquid and is discharged from the first liquid discharge port 15 of the process intensification unit 5, and then enters the pressure energy recovery unit 6 of the composite absorption tower 52. The rich absorption liquid is reduced in pressure from 8 MPa to 1.2 Mpa, and converts the pressure energy it possesses into kinetic energy, and impacts the power impeller 21 with pressurized liquid and drives the impeller to rotate, thereby driving the coaxially mounted rotor assembly 17 to rotate, and the rich absorption liquid after decompression enters the flash tank 55 to flash out the dissolved hydrocarbons, and then is heated up by the heat exchanger 57 and enters the regeneration tower 58, in which the rich absorption liquid is heated and decomposed to release the absorbed components to become lean absorption liquid, completing the regeneration of the absorption liquid, and the high-concentration CO2 gas released by the regeneration is subsequently treated, and the regenerated lean absorption liquid is pressurized, heat exchanged, cooled and filtered, and then returned to the composite absorption tower 52 for recycling.

[0048] Comparative Example 1 The same as Example 1, except that the natural gas decarbonization equipment adopts traditional tower equipment, and the whole process of gas-liquid contact in the traditional tower is carried out under normal gravity field. Due to the limitation of gravity field, the gas-liquid contact flow is slow, and the mass transfer coefficient is not high, resulting in low mass transfer rate, and the content of acidic components in the rich liquid is far lower than the equilibrium value. Compared with Example 1, when achieving the same treatment effect, the tower height of this comparative example is increased by 30%, and the amount of amine liquid used and the regeneration energy consumption are increased by about 20%.

[0049] Comparative Example 2 The same as Example 1, except that the natural gas decarbonization equipment adopts conventional supergravity equipment, and the drive of the conventional supergravity reactor bed (rotor) requires power from a motor. Under the same operating conditions as in Example 1, the system operating power consumption increases by more than 30%. In Example 1, a process intensification unit and a pressure energy recovery unit are arranged under the conventional absorption tower, and the system pressure energy is used to solve the motor energy consumption problem caused by the centrifugal field provided by the supergravity equipment, thereby realizing natural gas purification with high efficiency and low cost.

Claims

1. A composite absorption tower, characterized in that: The composite absorption tower comprises a tower body, a first baffle, a second baffle, a tower absorption unit, a process intensification unit and an energy recovery unit; The first baffle and the second baffle are arranged inside the tower body, dividing the tower body from top to bottom into three parts, namely, a tower absorption unit, a process intensification unit and an energy recovery unit; The tower absorption unit comprises a gas outlet, a demister, a first liquid inlet, a liquid distributor, an absorption tower section, a liquid collecting tower plate and a liquid collecting tray; The process intensification unit includes an air inlet, a first liquid discharge port, a liquid redistributor, a rotor assembly and a drive shaft; The pressure energy recovery unit includes a second liquid inlet, a second liquid outlet, a power impeller and a rotating shaft.

2. The composite absorption tower according to claim 1, characterized in that: The driving shaft of the process intensification unit and the rotating shaft of the pressure energy recovery unit are coaxially connected through the second partition plate.

3. The composite absorption tower according to claim 1, characterized in that: The first liquid discharge port is communicated with the second liquid inlet through a pipeline.

4. The composite absorption tower according to claim 1, characterized in that: The gas outlet of the tower absorption unit is arranged at the top of the tower body, the demister is arranged below the gas outlet, the first liquid inlet and the liquid distributor are arranged below the demister, the liquid distributor inlet is connected to the first liquid inlet, the absorption tower section is arranged below the liquid distributor, and the liquid collecting tower plate and the liquid collecting tray are arranged below the absorption tower section.

5. The composite absorption tower according to claim 1, characterized in that: The liquid collecting tower plate is a tower plate with air riser holes, the center of the liquid collecting tower plate is a hollow structure, an overflow weir is arranged on the hollow edge, and the lower edge of the hollow part in the middle of the liquid collecting tower plate is connected to the upper edge of the liquid collecting tray.

6. The composite absorption tower according to claim 1, characterized in that: The air inlet of the process intensification unit is arranged in the middle of the unit tower body, and the center of the inlet is radially horizontal to the rotor assembly. The first liquid discharge port is arranged at the lower position of the unit tower body, and the rotor assembly is arranged in the middle of the unit tower body. The liquid redistributor is vertically arranged at the center of the rotor assembly, and the upper end of the liquid redistributor is connected to the lower end of the liquid collection tray.

7. The composite absorption tower according to claim 1, characterized in that: The liquid accumulation tray passes through the first partition plate and is connected to the upper end of the liquid redistributor, and a gas phase channel is left between the liquid accumulation tray and the first partition plate.

8. The composite absorption tower according to claim 1, characterized in that: The rotor assembly is mounted on the drive shaft.

9. The composite absorption tower according to claim 1, characterized in that: The second liquid inlet of the pressure energy recovery unit is arranged on the side of the tower body of the unit, the center of the inlet is radially horizontal with the power impeller assembly, and the second liquid discharge port is located at the lower part or bottom of the tower body.

10. The composite absorption tower according to claim 1, characterized in that: The power impeller of the pressure energy recovery unit may be a single-stage or multi-stage impeller, and the power impellers are evenly arranged along the circumference and mounted on the rotating shaft.

11. The composite absorption tower according to claim 1, characterized in that: Sealing components are arranged between the rotor assembly and the reactor housing, and between the rotating shaft and the partition plate to ensure that there is no leakage in the mutual areas.

12. A gas processing system, characterized in that: It comprises the composite absorption tower described in any one of claims 1-11.

13. The gas processing system according to claim 12, characterized in that: The system includes a composite absorption tower, a flash tank, a lean and rich liquid heat exchanger, a regeneration tower, a lean liquid pump, a lean liquid cooler and a filtration system; wherein, The gas inlet of the composite absorption tower is connected to the raw gas pipeline, the gas outlet of the composite absorption tower is connected to the external gas pipeline, the first liquid inlet of the composite absorption tower is connected to the filter outlet, and the second liquid outlet of the composite absorption tower is connected to the liquid inlet of the flash tank; The liquid outlet of the flash tank is connected to the liquid inlet of the regeneration tower via a lean-rich liquid heat exchanger; The gas phase outlet of the regeneration tower is connected to the regeneration gas pipeline, and the liquid phase outlet of the regeneration tower is connected to the inlet of the lean liquid cooler after passing through the lean liquid pump and the lean-rich liquid heat exchanger in sequence; The lean liquid cooler outlet is connected to the filter system inlet.

14. The gas processing system according to claim 12, characterized in that The first liquid discharge port of the composite absorption tower process intensification unit is connected to the second liquid inlet of the pressure energy recovery unit.

15. A gas treatment method, characterized in that: A gas treatment system as described in any one of claims 12 to 14 is used.

16. The gas processing method according to claim 15, characterized in that: The steps include: (1) The gas to be treated first enters the process intensification unit of the composite absorption tower. The gas contacts the lean absorption liquid from the liquid redistributor in the rotor assembly area, undergoes the gas-liquid two-phase mass transfer intensification process and completes the initial absorption of the gas. The treated gas rises to the liquid collecting tower plate through the gas phase channel between the liquid collecting plate and the first partition plate, and then passes through the tower absorption unit of the composite tower from bottom to top through the gas rising holes of the liquid collecting tower plate. In this area, the gas is further absorbed and treated by the lean amine absorption liquid. The lean absorption liquid enters from the liquid inlet and passes through the liquid distributor, absorption tower section, liquid collecting plate, liquid redistributor and rotor assembly from top to bottom. After absorbing the components to be treated, it becomes rich absorption liquid and is discharged from the first liquid discharge port of the process intensification unit. (2) The rich absorbent discharged in step (1) enters the pressure energy recovery unit of the composite absorber, and the pressure energy of the rich absorbent is converted into kinetic energy. The pressurized liquid impacts the power impeller and drives the impeller to rotate, thereby driving the coaxially mounted rotor assembly to rotate. The depressurized fluid enters the flash tank from the second liquid discharge port of the pressure energy recovery unit; (3) The rich absorbent entering the flash tank in step (2) flashes off the dissolved hydrocarbons and then passes through the lean-rich liquid heat exchanger to be heated and enter the regeneration tower. In the regeneration tower, the rich absorbent is heated and decomposed to release the absorbed components to become lean absorbent, completing the regeneration of the absorbent. The high-concentration component gas released by the regeneration is subsequently treated. The regenerated lean absorbent is pressurized by a lean liquid pump, cooled by a lean-rich liquid heat exchanger, cooled by a lean liquid cooler, and filtered by a filtration system before returning to the composite absorber for recycling.

17. The gas processing method according to claim 15, characterized in that: The gas to be treated contains one or more of H2S, CO2 and H2O.

18. The gas processing method according to claim 15, characterized in that: The operating pressure of the composite absorption tower in step (1) is 0.3~20 MPa.

19. The gas processing method according to claim 15, characterized in that: The operating pressure of the regeneration tower in step (3) is lower than the operating pressure of the process intensification reactor, and the operating pressure difference is 0.2~20 MPa.

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