System for removing acid from a gas

Abstract

The utility model relates to chemical device technical field especially, more particularly to a kind of gas deacidification system, the gas deacidification system includes absorption tower, flash tank, lean rich liquid heat exchanger, regeneration tower, first cooler, reflux tank, first reflux pump, booster pump, lean liquid cooler, reboiler, compressor and first throttle valve, gas deacidification is carried out using the gas deacidification system provided by the utility model, energy consumption reduction depth is big, especially under high acid gas condition, lean liquid heat recovery rate is close to 100%, while more energy is not needed for lean liquid cooling consumption, low-grade heat source or waste heat is not needed in the field or nearby, application range is more extensive, and the gas deacidification system device provided by the utility model is simple, and investment cost is not increased.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, and in particular to a gas deacidification system. Background Technology

[0002] Amine-based deacidification utilizes a reversible reaction between an alkaline absorbent and acidic gas to generate a compound containing the acidic gas. This compound regenerates the alkaline absorbent under high temperature and low pressure conditions, simultaneously releasing the acidic gas, which is then sent to a subsequent tail gas treatment unit. Amine-based deacidification (such as MEA, DEA, MDEA, etc.) is the most widely used CO2 capture and gas deacidification technology in industry, but its high energy consumption has always been a major bottleneck restricting its economic viability.

[0003] Current alkanolamine deacidification units suffer from persistently high energy consumption, with limited energy reduction methods, restricted application scenarios, and insufficient depth of energy reduction. For example, the lean-rich liquor heat exchange (recovering regeneration heat) technology, especially for units with high acid gas content, is problematic because the absorption reaction is exothermic, and the temperature of the rich amine solution exiting the absorber is already very high. Lean-rich liquor heat exchange can only recover 30%-60% of the heat from the high-temperature lean liquor, resulting in still high regeneration energy consumption. Furthermore, the high-temperature lean liquor needs further cooling to 40-50°C before returning to the absorber, and current technologies cannot reduce this cooling energy consumption.

[0004] The energy consumption of the amine-based deacidification process is mainly concentrated in the solvent regeneration (desorption) stage, accounting for 60% to 80% of the total energy consumption, with the remaining energy consumption distributed in auxiliary systems such as compression, pumping, and cooling. Therefore, it is desirable to provide a new low-energy-consumption gas deacidification system. Utility Model Content

[0005] To address the aforementioned technical problems, this invention provides a gas deacidification system. Utilizing this system for gas deacidification significantly reduces energy consumption, especially under high acid content gas conditions, achieving a near 100% heat recovery rate for lean liquor. Furthermore, it eliminates the need for additional energy consumption for cooling the lean liquor, and requires no low-grade heat sources or waste heat on-site or nearby, thus broadening its application range. Moreover, the gas deacidification system provided by this invention is simple to install and does not increase investment costs.

[0006] In a first aspect, this utility model provides a gas deacidification system, which includes an absorption tower, a flash tank, a lean and rich liquid heat exchanger, a regeneration tower, a first cooler, a reflux tank, a first reflux pump, a booster pump, a lean liquid cooler, a reboiler, a compressor, and a first throttling valve.

[0007] The absorption tower is used to chemically absorb acidic gases from a lean amine solution to obtain a rich amine solution;

[0008] The flash tank is used to flash evaporate the amine-rich solution flowing out of the absorption tower;

[0009] The regeneration tower is used to heat the rich amine solution after flash evaporation in the flash tank to regenerate a poor amine solution and an acidic gas containing trace amounts of amine solution.

[0010] The rich and lean amine solution heat exchanger is installed between the flash tank and the regeneration tower to exchange heat and raise the temperature of the rich amine solution after flashing in the flash tank, and to exchange heat and lower the temperature of the lean amine solution flowing out of the regeneration tower.

[0011] The first cooler is used to cool the acidic gas containing trace amounts of amine liquid after regeneration in the regeneration tower to obtain a mixture of acidic gas and amine liquid;

[0012] The reflux tank is used to separate the mixture of acidic gas and amine liquid obtained by cooling the first cooler to obtain acidic gas and amine liquid;

[0013] The first reflux pump is used to reflux the amine solution in the reflux tank back to the regeneration tower;

[0014] The lean liquid cooler and the reboiler are connected in series through a first pipe to form a loop, and the first pipe contains refrigerant. The lean liquid cooler is used to further cool the lean amine solution after it has been cooled by the lean-rich liquid heat exchanger. The reboiler is used to supply heat to the regeneration tower. The refrigerant is used to transfer heat between the lean liquid cooler and the reboiler. The lean liquid cooler of this invention acts as an evaporator in a heat pump system to further recover the heat of the lean amine solution and reduce the energy consumption of the entire system.

[0015] The compressor is located between the lean liquid cooler and the reboiler, and is used to compress the refrigerant that has absorbed heat and vaporized in the lean liquid cooler and then introduce it into the reboiler; the form of the compressor is not limited, as long as it can meet the purpose.

[0016] The first throttle valve is installed on the first pipeline to reduce the pressure of the refrigerant that condenses after heating in the reboiler and allows it to enter the lean liquid cooler.

[0017] The booster pump is used to return the lean amine solution, which has been cooled by the lean solution cooler, to the absorption tower.

[0018] Furthermore, the gas deacidification system also includes a second throttling valve, which is disposed between the absorption tower and the flash tank, for depressurizing the amine-rich solution flowing out of the absorption tower.

[0019] Furthermore, the absorption tower has a lean amine solution inlet, an acidic gas inlet, a purified gas outlet, and a rich amine solution outlet. The height of the lean amine solution inlet is higher than the height of the acidic gas inlet. The purified gas outlet is located at the top of the absorption tower, and the rich amine solution outlet is located at the bottom of the absorption tower.

[0020] Furthermore, the purified gas outlet of the absorption tower is connected to a second pipeline, and a third throttle valve is installed on the second pipeline.

[0021] Furthermore, the flash tank has a rich amine solution inlet, a rich amine solution outlet, and a flash gas outlet. The height of the rich amine solution inlet is higher than the height of the rich amine solution outlet, and the flash gas outlet is located at the top of the flash tank.

[0022] Furthermore, the reflux tank has an inlet for a mixture of acidic gas and amine liquid, an outlet for acidic gas, and an outlet for amine liquid. The acidic gas outlet is located at the top of the reflux tank, and the amine liquid outlet is located at the bottom of the reflux tank.

[0023] Secondly, this utility model provides a gas deacidification process, which utilizes the gas deacidification system described in the first aspect and includes the following steps:

[0024] Acidic gas and lean amine solution are chemically absorbed by countercurrent contact in an absorption tower to obtain a rich amine solution. The rich amine solution enters a flash tank for flash evaporation. The flash-evaporated rich amine solution enters a lean-rich solution heat exchanger for heat exchange and temperature increase. The heated rich amine solution enters a regeneration tower for heating and regeneration to obtain acidic gas containing trace amounts of amine solution and a lean amine solution.

[0025] The acidic gas containing trace amounts of amine solution is cooled by the first cooler and then enters the reflux tank for separation to obtain acidic gas and amine solution. The acidic gas is discharged, and the amine solution is returned to the regeneration tower by the first reflux pump to complete the cycle.

[0026] The regenerated lean amine solution in the regeneration tower enters the lean-rich liquid heat exchanger for heat exchange and cooling. After cooling, the lean amine solution enters the lean liquid cooler for heat exchange and cooling again. Then, it is pressurized by the booster pump and returned to the absorption tower to complete the cycle.

[0027] The refrigerant absorbs heat from the lean liquid cooler to form a gaseous refrigerant. After being compressed by the compressor, it enters the reboiler to heat the regeneration tower and then condenses to form a liquid refrigerant. The liquid refrigerant is depressurized by the first throttling valve and then enters the lean liquid cooler again to complete the cycle.

[0028] Furthermore, the purified gas obtained after the acidic gas and the lean amine solution undergo countercurrent contact for chemical absorption in the absorption tower flows out from the purified gas outlet, and enters the downstream device after being stabilized by the third throttle valve.

[0029] Furthermore, the rich amine solution is depressurized by a second throttling valve before entering the flash tank for flash evaporation.

[0030] Furthermore, the acidic gas includes CO2 and / or H2S.

[0031] Furthermore, the refrigerant includes any one or more of the following refrigerants: R1233zd(E), R245fa, R601a, and R1336mzz(Z).

[0032] The technical solution provided by this utility model has the following advantages compared with the prior art:

[0033] The gas deacidification system provided by this invention significantly reduces energy consumption, especially under high acid content gas conditions, with a lean liquid heat recovery rate approaching 100%. At the same time, it does not require more energy to cool the lean liquid, and no low-grade heat source or waste heat is needed on-site or nearby, making its application range wider. Moreover, the gas deacidification system provided by this invention is simple to install and will not increase investment costs. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0035] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the gas deacidification system described in Embodiment 1 of this utility model. Detailed Implementation

[0037] To better understand the above-mentioned objectives, features, and advantages of this utility model, the solution of this utility model will be further described below. It should be noted that, unless otherwise specified, the embodiments of this utility model and the features thereof can be combined with each other.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the present invention, and not all embodiments.

[0039] Example 1

[0040] This embodiment provides a gas deacidification system, which is an alcohol amine method coupled with a heat pump system, and its structural schematic diagram is shown below. Figure 1 As shown.

[0041] Specifically, the gas deacidification system includes an absorption tower 10, a flash tank 11, a lean and rich liquid heat exchanger 12, a regeneration tower 13, a first cooler 14, a reflux tank 15, a first reflux pump 16, a booster pump 17, a lean liquid cooler 18, a reboiler 19, a compressor 20, a first throttle valve 21, a second throttle valve 22, and a third throttle valve 23;

[0042] The absorption tower 10 has a lean amine solution inlet, an acid gas inlet, a purified gas outlet, and a rich amine solution outlet. The height of the lean amine solution inlet is higher than the height of the acid gas inlet. The purified gas outlet is located at the top of the absorption tower 10, and the rich amine solution outlet is located at the bottom of the absorption tower 10. The purified gas outlet is connected to a second pipeline, and a third throttle valve 23 is installed on the second pipeline. The absorption tower 10 is used to chemically absorb the acid gas with the lean amine solution to obtain a rich amine solution.

[0043] The second throttle valve 22 is used to depressurize the rich amine solution flowing out of the absorption tower 10; the flash tank 11 has a rich amine solution inlet, a rich amine solution outlet, and a flash gas outlet. The height of the rich amine solution inlet is higher than the height of the rich amine solution outlet, and the flash gas outlet is located at the top of the flash tank 11. The flash tank 11 is used to flash the depressurized rich amine solution; the regeneration tower 13 is used to heat the rich amine solution flashed in the flash tank 11 to regenerate a lean amine solution and an acidic gas containing trace amounts of amine solution.

[0044] The rich and lean amine solution heat exchanger 12 is installed between the flash tank 11 and the regeneration tower 13. It is used to exchange heat and raise the temperature of the rich amine solution after flashing in the flash tank 11, and to exchange heat and lower the temperature of the lean amine solution flowing out of the regeneration tower 13.

[0045] The first cooler 14 is used to cool the acidic gas containing trace amounts of amine liquid after regeneration in the regeneration tower 13; the reflux tank 15 has an inlet for a mixture of acidic gas and amine liquid, an acidic gas outlet, and an amine liquid outlet. The acidic gas outlet is located at the top of the reflux tank 15, and the amine liquid outlet is located at the bottom of the reflux tank 15. The reflux tank 15 is used to separate the mixture of acidic gas and amine liquid obtained by cooling in the first cooler 14 to obtain acidic gas and amine liquid; the first reflux pump 16 is used to reflux the amine liquid in the reflux tank 15 back to the regeneration tower 13;

[0046] The lean liquid cooler 18 and the reboiler 19 are connected in series through a first pipe to form a loop, and the first pipe contains refrigerant. The lean liquid cooler 18 is used to further cool the lean amine solution after it has been cooled by the lean and rich liquid heat exchanger 12. The reboiler 19 is used to heat the regeneration tower 13. The refrigerant is used to transfer heat between the lean liquid cooler 18 and the reboiler 19.

[0047] The compressor 20 is located between the lean liquid cooler 18 and the reboiler 19, and is used to compress the refrigerant that has absorbed heat and vaporized in the lean liquid cooler 18 into the reboiler 19.

[0048] A first throttling valve 21 is installed on the first pipeline. The first throttling valve 21 is used to reduce the pressure of the refrigerant that condenses after heating in the reboiler 19 and allow it to enter the lean liquid cooler 18.

[0049] The booster pump 17 is used to return the lean amine solution cooled by the lean solution cooler 18 to the absorption tower 10.

[0050] Comparative Example 1

[0051] This comparative example provides a gas deacidification system with the same structural schematic as Example 1. The difference from Example 1 is that the heat pump system is not coupled in this comparative example, that is, there is no compressor 20 and first throttle valve 21, and there is no pipeline connection between the lean liquid cooler 18 and the reboiler 19. The lean liquid cooler 18 uses air cooling to cool the lean amine solution after heat exchange and cooling by the lean and rich liquid heat exchanger 12. The reboiler 19 provides heat to the regeneration tower 13 through electric heating.

[0052] Example 2

[0053] This embodiment provides a gas deacidification process, which utilizes the gas deacidification system described in Embodiment 1, and includes the following steps:

[0054] After compression and cooling pretreatment, the acidic gas is introduced into the absorption tower 10 and chemically absorbed by the lean amine solution in the countercurrent contact in the absorption tower 10 to obtain purified gas and rich amine solution. The purified gas is then pressure-stabilized by the third throttle valve 23 and enters the downstream device. The rich amine solution is depressurized by the second throttle valve 22 and enters the flash tank 11 for flash evaporation. The flash vapor is discharged from the flash vapor outlet and enters the downstream treatment device. The flashed rich amine solution enters the lean-rich liquid heat exchanger 12 for heat exchange and temperature increase. The heated rich amine solution enters the regeneration tower 13 for heating and regeneration to obtain acidic gas containing trace amounts of amine solution and lean amine solution.

[0055] The acidic gas containing trace amounts of amine solution is cooled by the first cooler 14 and then enters the reflux tank 15 for separation to obtain acidic gas and amine solution. The acidic gas is discharged and the amine solution is returned to the regeneration tower 13 by the first reflux pump 16 to complete the cycle.

[0056] The regenerated lean amine solution in regeneration tower 13 enters lean-rich liquid heat exchanger 12 for heat exchange and cooling. After cooling, the lean amine solution enters lean liquid cooler 18 for heat exchange and cooling to about 45°C. Then, it is pressurized by booster pump 17 and returned to absorption tower 10 to complete the cycle.

[0057] The lean liquid cooler 18 serves as the evaporator of the heat pump system, and the reboiler 19 serves as the condenser of the heat pump system. The refrigerant absorbs heat from the lean liquid cooler 18 to form a gaseous refrigerant. After being compressed by the compressor 20, it enters the reboiler 19 to heat the regeneration tower 13 and then condenses to form a liquid refrigerant. The liquid refrigerant is depressurized by the first throttling valve 21 and then re-enters the lean liquid cooler 18 as a two-phase gas-liquid mixture to complete the cycle.

[0058] The acidic gas is a wellhead gas, and its specific composition is shown in Table 1:

[0059] Table 1

[0060] Components <![CDATA[CH4]]> <![CDATA[C2H6]]> <![CDATA[N2]]> <![CDATA[CO2]]> <![CDATA[O2]]> <![CDATA[H2S]]> ∑ Content % (V) 48.5 1.1 5 44.3 1.1 <![CDATA[15000mg / m 3 ]]> 100

[0061] Gas volume of the device: 8.5 × 10 4 m 3 / d (standard conditions);

[0062] Requirement: The H2S content of the purified gas should be ≤10mg / m³ 3 CO2 concentration > 90%.

[0063] Methane pressure: 0.6 MPa, methane concentration > 80%.

[0064] Comparative Example 2

[0065] This comparative example provides a gas deacidification process, which is carried out using the gas deacidification system described in Comparative Example 1, wherein the specific composition of the acidic gas is the same as that in Example 2.

[0066] The comparison revealed that, based on the fact that both the lean and rich liquid heat exchangers in Example 2 and Comparative Example 2 recover 1300KW of heat, the regeneration tower requires 2200KW of regeneration energy, and the lean liquid cooler has a load of 1350KW.

[0067] In Example 2, after coupling the heat pump system, the lean liquid cooler can recover 1350KW of lean liquid heat, the heat pump system compressor power is 700KW, the heat pump system heating load is 2050KW, and 150KW of auxiliary heat needs to be regenerated.

[0068] In contrast, in the uncoupled heat pump system of Comparative Example 2, the lean liquid cooler load of 1350KW of heat (which is lost) requires the consumption of 20KW of electrical energy.

[0069] Therefore, the actual energy saving of Example 2 compared to Comparative Example 2 is 2200+20-(700+150)=1370KW.

[0070] It is evident that the gas deacidification system provided by this invention significantly reduces energy consumption.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas deacidification system, characterized in that, The gas deacidification system includes an absorption tower (10), a flash tank (11), a lean and rich liquid heat exchanger (12), a regeneration tower (13), a first cooler (14), a reflux tank (15), a first reflux pump (16), a booster pump (17), a lean liquid cooler (18), a reboiler (19), a compressor (20), and a first throttle valve (21). The absorption tower (10) is used to chemically absorb acidic gases from a lean amine solution to obtain a rich amine solution; The flash tank (11) is used to flash evaporate the rich amine solution flowing out of the absorption tower (10); The regeneration tower (13) is used to heat the rich amine solution after flash evaporation in the flash tank (11) to regenerate a poor amine solution and an acidic gas containing trace amounts of amine solution; The lean and rich liquid heat exchanger (12) is located between the flash tank (11) and the regeneration tower (13) for heat exchange and heating of the rich amine solution after flash evaporation in the flash tank (11) and heat exchange and cooling of the lean amine solution flowing out of the regeneration tower (13). The first cooler (14) is used to cool the acidic gas containing trace amounts of amine liquid after regeneration by the regeneration tower (13) to obtain a mixture of acidic gas and amine liquid; The reflux tank (15) is used to separate the mixture of acidic gas and amine liquid obtained by cooling the first cooler (14) to obtain acidic gas and amine liquid; The first reflux pump (16) is used to reflux the amine solution in the reflux tank (15) back to the regeneration tower (13); The lean liquid cooler (18) and the reboiler (19) are connected in series through a first pipe to form a loop, and the first pipe contains refrigerant; the lean liquid cooler (18) is used to further cool the lean amine solution after it has been cooled by the lean-rich liquid heat exchanger (12); the reboiler (19) is used to supply heat to the regeneration tower (13); the refrigerant is used to transfer heat between the lean liquid cooler (18) and the reboiler (19); The compressor (20) is located between the lean liquid cooler (18) and the reboiler (19) and is used to compress the refrigerant that has absorbed heat and vaporized in the lean liquid cooler (18) and put it into the reboiler (19). The first throttle valve (21) is installed on the first pipeline to reduce the pressure of the refrigerant that condenses after heating in the reboiler (19) and allow it to enter the lean liquid cooler (18); The booster pump (17) is used to return the lean amine solution cooled by the lean solution cooler (18) to the absorption tower (10).

2. The gas deacidification system according to claim 1, characterized in that, The gas deacidification system also includes a second throttle valve (22), which is disposed between the absorption tower (10) and the flash tank (11) for depressurizing the amine-rich solution flowing out of the absorption tower (10).

3. The gas deacidification system according to claim 1 or 2, characterized in that, The absorption tower (10) has a lean amine solution inlet, an acid gas inlet, a purified gas outlet and a rich amine solution outlet. The height of the lean amine solution inlet is higher than the height of the acid gas inlet. The purified gas outlet is located at the top of the absorption tower (10) and the rich amine solution outlet is located at the bottom of the absorption tower (10).

4. The gas deacidification system according to claim 3, characterized in that, The purified gas outlet of the absorption tower (10) is connected to the second pipeline, and a third throttle valve (23) is installed on the second pipeline.

5. The gas deacidification system according to claim 1 or 2, characterized in that, The flash tank (11) has a rich amine solution inlet, a rich amine solution outlet and a flash gas outlet. The height of the rich amine solution inlet is higher than the height of the rich amine solution outlet, and the flash gas outlet is located at the top of the flash tank (11).

6. The gas deacidification system according to claim 1 or 2, characterized in that, The reflux tank (15) has an inlet for a mixture of acidic gas and amine liquid, an outlet for acidic gas and an outlet for amine liquid, with the acidic gas outlet located at the top of the reflux tank (15) and the amine liquid outlet located at the bottom of the reflux tank (15).

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