A method of treating shale gas

Abstract

This invention discloses a method for processing shale gas, relating to the field of natural gas development and processing technology. The method includes using a three-phase separator to separate cooled raw shale gas to obtain a gas phase; using an absorbent to decarbonize the reheated gas phase of the raw shale gas in a deacidification unit; selecting a dehydration unit comprising three adsorption towers, each containing an adsorbent; injecting the decarbonized raw shale gas phase into any one of the adsorption towers for dehydration; introducing regenerated gas into any one of the remaining two adsorption towers, allowing heat from that tower to enter the regenerated gas; subsequently heating the regenerated gas; and injecting the heated regenerated gas into the last adsorption tower for desorption of the adsorbent in that tower, thereby obtaining purified natural gas. This method reduces energy consumption in the dehydration step of shale gas post-processing.

Description

Technical Field

[0001] This invention relates to the field of natural gas development and processing technology, and in particular to a method for processing shale gas. Background Technology

[0002] Shale gas post-processing technologies mainly involve gas purification, dehydration, desulfurization, and condensate recovery, aiming to improve the purity and commercial value of shale gas. Dehydration is a core step, removing moisture from the extracted gas to prevent pipeline corrosion, hydrate blockage, and reduced calorific value, ensuring safe transportation and combustion efficiency. This technology must balance energy consumption, environmental friendliness, and economic viability, and is a crucial guarantee for the industrial application of shale gas.

[0003] Shale gas extraction is accompanied by large amounts of formation water and condensate, with a water content significantly higher than conventional natural gas. Traditional dehydration technologies mainly include triethylene glycol (TEG) absorption, solid adsorption (such as molecular sieves), and cryogenic condensation. The TEG method has become mainstream due to its low cost and high stability, regenerating and recycling water through solvent absorption, but it suffers from high energy consumption and solvent degradation issues. Molecular sieves offer high dehydration efficiency, but require large equipment investments and frequent adsorbent replacements. Cryogenic condensation is suitable for high-pressure environments but lacks flexibility. Existing technologies generally face challenges such as high energy consumption, secondary pollution, or insufficient adaptability, necessitating optimization and innovation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing shale gas to solve the above-mentioned problems.

[0005] This invention is achieved through the following technical solution:

[0006] A method for processing shale gas includes:

[0007] S1: Using a compressor to pressurize the raw shale gas:

[0008] S2: The pressurized raw shale gas is lightly cooled, and a three-phase separator is used to separate the cooled raw shale gas to obtain the gas phase of the raw shale gas. The gas phase temperature of the raw shale gas is then reheated.

[0009] S3: Select a deacidification unit, use an absorbent to decarbonize the gas phase of the reheated original shale gas through the deacidification unit, and produce carbon dioxide;

[0010] S4: Select a dehydration unit, which includes three sets of adsorption towers, each equipped with an adsorbent. Inject the decarbonized raw shale gas phase into any one set of adsorption towers for dehydration. Introduce regenerated gas into any one of the remaining two sets of adsorption towers. The heat from that set of adsorption towers enters the regenerated gas, which is then heated. The heated regenerated gas is then injected into the last set of adsorption towers, where the adsorbent is heated and desorbed. Repeat the above steps until all the decarbonized gas phases are dehydrated to obtain purified natural gas.

[0011] S5: Select a light hydrocarbon recovery unit to recover light hydrocarbons from purified natural gas and purify the carbon dioxide discharged from the deacidification unit to obtain liquid carbon dioxide.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] This invention, through the design of three sets of adsorption towers, ensures that one set of adsorption towers remains operational throughout the dehydration unit's operation. Compared to existing technologies, the adsorption time in this solution is the heating time within the combined heating and cooling adsorption time, effectively reducing the amount of adsorbent required per tower, thereby reducing equipment weight and the need for equipment disposal. Furthermore, the reduced amount of adsorbent per tower also effectively lowers the heating and cooling loads, reducing the consumption of regeneration heat and cooling circulating water, thus significantly reducing the energy consumption of this solution.

[0014] Furthermore, the design of the circulating regenerated gas in this scheme enables the reuse of heat during the heating and cooling processes, further reducing energy consumption during implementation. Compared with the existing two-tower or two-and-a-half-tower isobaric processes, it has unique advantages.

[0015] Further, in step S4, before injecting the decarbonized raw shale gas phase into any set of adsorption towers, the raw shale gas phase is divided into two equal parts. One part is selected and fed into an adsorption tower for dehydration treatment. The other part of the raw shale gas phase is used as circulating regeneration gas and enters an adsorption tower that is currently being cooled to absorb heat from the adsorption tower. Then, this part of the gas phase is heated and, after heating, is fed into the last set of adsorption towers for heating treatment. After heating treatment, a cooler is used to cool this part of the gas phase, and a gas-liquid separator is used to remove the liquid phase from this part of the raw shale gas phase. This part of the raw shale gas phase is then mixed with the other part of the raw shale gas phase to complete the dehydration treatment of the raw shale gas phase after decarbonization.

[0016] Beneficial effects: In this scheme, the gas phase of the original shale gas is divided into two parts. One part is directly dehydrated, and the other part is used as circulating regeneration gas to cool and heat the adsorption tower. Compared with the existing technology, this scheme can further utilize the heat during the heating and cooling process. At the same time, this scheme can achieve staged dehydration of the gas phase of the original shale gas, reducing the corrosion of metal components in the reaction system caused by the excessive dryness of the original shale gas phase, thus reducing its service life.

[0017] Furthermore, in S5, the light hydrocarbon recovery unit includes a demethanizer. The steps for light hydrocarbon recovery are as follows: cooling the purified natural gas and using a liquid hydrocarbon separator to separate the cooled purified natural gas into gas and liquid products, obtaining gaseous and liquid products, selecting a demethanizer, using the gaseous product as the middle feed of the demethanizer and the liquid product as the top feed of the demethanizer, and obtaining a mixed liquid hydrocarbon product through the distillation of the demethanizer.

[0018] Beneficial effects: Compared with existing technologies, this solution obtains mixed liquid hydrocarbon products by cooling and separating purified natural gas, which helps to enhance the value of raw shale gas products. At the same time, separating light hydrocarbons can reduce the dew point of natural gas and effectively prevent the precipitation of liquid hydrocarbons during transportation.

[0019] Furthermore, in step S5, after obtaining the mixed liquid hydrocarbon product, an ethane stripper, a propane stripper, and a butane stripper are selected, and the mixed liquid hydrocarbon product is passed through the ethane stripper, propane stripper, and butane stripper in sequence to obtain the top distillate gas. After the top distillate gas is throttled and depressurized, an active heat exchanger is used to reheat the throttled and depressurized top distillate gas.

[0020] Beneficial effects: Compared with existing technologies, this solution can obtain commercial natural gas by extracting ethane, propane, and butane, and then mixing the purified ethane, propane, and butane with methane in the required proportions, thereby further enhancing the economic value of raw shale gas.

[0021] Furthermore, in step S5, a mixed refrigerant is used to cool the purified natural gas. Before cooling the purified natural gas, a booster compressor is used to pressurize and separate the mixed refrigerant to obtain a gaseous refrigerant and a liquid refrigerant. The gaseous and liquid refrigerants are cooled separately, and a flash tank is selected. The liquid refrigerant is throttled and depressurized before being introduced into the flash tank, and the gaseous refrigerant is throttled and depressurized before being introduced into the demethanizer to cool the gas in the demethanizer. After cooling, the gaseous refrigerant is introduced into the flash tank to merge with the liquid refrigerant. After the merged refrigerant is reheated, the refrigerant is injected back into the booster compressor.

[0022] Beneficial effects: This solution utilizes refrigerant recycling to construct a closed-loop refrigeration system. Compared with existing technologies, this solution effectively reduces refrigerant consumption during the operation of the reaction system, thereby reducing reaction costs. Furthermore, compared with open cooling systems, this solution has lower maintenance costs and more significant economic advantages.

[0023] Furthermore, the absorbent used in S3 is a complex amine.

[0024] Beneficial effects: Because the compound amine solution can undergo a rapid and reversible reaction with carbon dioxide, the absorption rate of this solution is greatly improved compared to the solution using traditional physical solvents. At the same time, operators can adjust the concentration of the compound amine solution and other parameters as needed to meet different carbon dioxide partial pressure requirements, thus making this solution adaptable.

[0025] Furthermore, in S3, the deacidification unit includes a first absorption tower, with a first regeneration tower fitted outside the first absorption tower. A heating component is installed inside the outer wall of the first regeneration tower to heat the first regeneration tower. The bottom wall of the first absorption tower is connected to the bottom wall of the first regeneration tower. A conveying component is connected to the input end of the first absorption tower. The conveying component is used to inject absorbent into the first absorption tower and to inject the gas phase of the original shale gas into the first absorption tower. The first absorption tower is used to allow the absorbent to react with carbon dioxide in the gas phase and to transfer the heat of reaction to the first regeneration tower. The first regeneration tower is used to perform gas stripping regeneration of the absorbent that has absorbed carbon dioxide. The conveying component is also used to inject absorbent into the first absorption tower when the lean liquid degree of the absorbent in the first regeneration tower reaches a preset value.

[0026] Beneficial effects: This scheme utilizes the absorption characteristics of the absorbent during the desorption of carbon dioxide to cool the absorbent in the first absorption tower, effectively preventing the absorbent from degrading due to a sharp increase in temperature caused by the heat of reaction. At the same time, the temperature of the absorbent in the first regeneration tower rises, thereby preheating the absorbent before regeneration and preventing partial degradation of the absorbent that may occur due to a sudden increase in temperature.

[0027] Furthermore, the heating assembly includes a reboiler, which is connected to a heat exchange tube. The heat exchange tube contains heat transfer oil. The reboiler is used to heat the heat transfer oil, and the heat transfer oil is used to transfer heat to the absorbent. The heat exchange tube is also connected to a circulation pump, which is used to drive the heat transfer oil to circulate in the heat exchange tube.

[0028] The deacidification unit also includes a control system, which is used to collect temperature information at various locations in the first regeneration tower, determine the temperature distribution of the fluid in the first regeneration tower based on the temperature information, and control the reboiler and the circulating pump to work based on the temperature distribution in the first regeneration tower.

[0029] Beneficial effects: Compared with existing technologies, this solution can monitor the liquid level of the absorbent in the first regeneration tower by using temperature information, thereby achieving precise control of the reboiler and circulating pump, and reducing the energy consumption of the reboiler and circulating pump during the implementation of the solution.

[0030] Furthermore, the control system obtains the rate of rise of the absorbent liquid level based on the temperature distribution in the first regeneration tower, and determines whether the heat exchange tube is leaking based on the rate of rise of the absorbent liquid level. When the heat exchange tube is leaking, the control system shuts down the circulation pump and the reboiler.

[0031] Beneficial effects: Compared with existing technologies, this solution can monitor whether the heat exchange tube is leaking by judging the rate of rise of the absorbent liquid level, thereby improving the safety of the solution implementation.

[0032] Furthermore, a cooling component is provided on the conveying assembly. The cooling component is used to reduce the temperature of the absorbent entering the first absorption tower. The cooling component includes a main pipe, the input end of which is connected to the conveying assembly, and the output end of which is connected to the input end of the first absorption tower. A branch pipe is provided on either side of the main pipe, and both ends of the branch pipe are connected to the side wall of the main pipe. A semiconductor cooling chip is installed on the side wall of the branch pipe.

[0033] Beneficial effects: This solution uses the design of main pipe and branch pipes to divert the absorbent, resulting in a greater temperature difference when the two converge. This promotes the efficiency of heat transfer during the mixing process, improves the uniformity of the internal temperature of the absorbent, and reduces the thermal degradation of the absorbent that may be caused by excessively high local temperatures in the existing technology. Attached Figure Description

[0034] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a flowchart of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0038] Figure 4 This is an isometric view of the first absorption tower and the regeneration tower in this invention;

[0039] Figure 5 This is a top view of the first absorption tower and the regeneration tower in this invention;

[0040] Figure 6 for Figure 4 Cross-sectional view along the AA direction;

[0041] Figure 7 for Figure 4 Cross-sectional view along the BB direction.

[0042] The reference numerals in the attached figures represent: 1. Compressor; 2. Refrigeration unit; 3. Three-phase separator; 4. Deacidification unit; 41. Flash tank; 42. First regeneration tower; 421. Channel; 43. First absorption tower; 44. Heating assembly; 441. Reboiler; 442. Circulating pump; 443. Heat exchange tube; 45. Cooling assembly; 451. Main pipe; 452. Branch pipe; 46. Second regeneration tower; 47. Second absorption tower; 5. Dehydration unit; 51. Adsorption tower; 52. Heat exchanger; 53. Steam heater; 54. Electric heater; 55. Cooler; 56. Gas-liquid separator; 6. Light hydrocarbon recovery unit; 61. Demethanizer; 62. Deethaner; 63. Debutanizer; 7. Heat exchange cooler. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. It should be noted that this invention is already in the actual research and development stage.

[0044] Example 1

[0045] like Figures 1 to 2 As shown, this embodiment includes:

[0046] S1: After separating free water and impurities from the raw shale gas, compressor 1 is used to pressurize the raw shale gas to 2.6 MPa(g):

[0047] S2: The pressurized raw shale gas is lightly cooled. After the temperature of the raw shale gas is lowered to 20 degrees Celsius using refrigeration unit 2, the cooled raw shale gas is separated using three-phase separator 3 to obtain the gas phase of the raw shale gas. The temperature of the gas phase of the raw shale gas is then reheated to 35 degrees Celsius.

[0048] S3: Select deacidification unit 4 and use absorbent to decarbonize the reheated gas phase. In this embodiment, deacidification unit 4 uses second absorption tower 47 and the absorbent is a compound amine solution. The reheated gas phase passes through the second absorption tower 47 from bottom to top, and the absorbent passes through the second absorption tower 47 from top to bottom. During this process, the original shale gas phase reacts with the absorbent in the second absorption tower 47. The carbon dioxide in the gas enters the conventional absorbent, and the unabsorbed part of the gas leaves from the top of the second absorption tower 47 and enters the heat exchange cooler 7. The heat exchange cooler 7 cools it to complete the decarbonization of the gas. The absorbent that absorbs carbon dioxide becomes rich liquid. The rich liquid flows out from the bottom of the second absorption tower 47. Then, the rich liquid is heated and desorbed using the second regeneration tower 46 to obtain carbon dioxide gas. After the lean liquid obtained after heating and desorption in the second regeneration tower 46 reaches the preset value, it is injected into the second absorption tower 47.

[0049] S4: Select dehydration unit 5, which includes three sets of adsorption towers 51. In this embodiment, each set of adsorption towers 51 contains one adsorbent. The decarbonized gas phase is injected into any set of adsorption towers 51 for dehydration. Circulating regeneration gas is introduced into any set of adsorption towers 51 from the remaining two sets of adsorption towers 51. The heat in this set of adsorption towers 51 enters the circulating regeneration gas (i.e., the circulating regeneration gas is used to cold-purge this set of adsorption towers 51). Then, a heat exchanger 52, a steam heater 53, and an electric heater 54 are used to heat the temperature of the circulating regeneration gas to 200-220 degrees Celsius. The heated circulating regeneration gas is then injected into the last set of adsorption towers 51 to heat and desorb the adsorbent in this set of adsorption towers 51. The above steps are repeated until all the decarbonized gas phases are dehydrated to obtain purified natural gas.

[0050] Compared to existing technologies, this solution utilizes three adsorption towers 51 working in tandem, ensuring that at least one adsorption tower 51 is always in the adsorption and dehydration state during the dehydration process. Therefore, compared to conventional two-tower or two-tower semi-dehydration solutions, the adsorption time per tower in this solution is the heating time within the combined heating and cooling time of conventional solutions (i.e., at any given time during adsorption, one adsorption tower 51 is in operation, eliminating the need for separate cooling or heating of any single adsorption tower 51). This effectively improves adsorption efficiency. While maintaining the same efficiency as existing technologies, this solution reduces the amount of adsorbent required per tower, thereby reducing the overall weight of the equipment and lowering the initial equipment cost. Furthermore, the reduction in adsorbent and equipment weight lowers the heating and cooling loads in the entire reaction system, which is beneficial for reducing the consumption of regeneration heat and cooling circulating water, thus reducing the overall energy consumption of the reaction system and achieving energy conservation.

[0051] Before the decarbonized gas phase is injected into any set of adsorption towers 51, the gas phase is divided into two parts. One part is selected and fed into adsorption tower 51 for dehydration treatment. The other part of the gas phase is used as circulating regeneration gas and enters a set of adsorption towers 51 that is being cooled to absorb heat from the adsorption towers 51. Then, the gas phase is heated and fed into the last set of adsorption towers 51 for heating treatment. After the heating treatment is completed, the gas phase is cooled using a cooler 55 and the liquid phase in the gas phase is removed using a gas-liquid separator 56. The gas phase is then mixed with the other part of the gas phase to complete the dehydration treatment of the decarbonized gas phase.

[0052] Compared to existing technologies, this scheme divides the gaseous phase of the decarbonized raw shale gas into two parts. One part is directly dehydrated, while the other part undergoes heating and cooling regeneration in adsorption tower 51. This allows for the reuse of energy during heating and cooling, further reducing the heat energy consumption of the reaction system. Simultaneously, this scheme avoids excessive drying of the raw shale gas, preventing corrosion of pipes and other metal components within the reaction system and extending their service life.

[0053] S5: Select light hydrocarbon recovery unit 6. Use light hydrocarbon recovery unit 6 to recover light hydrocarbons from purified natural gas. Light hydrocarbon recovery unit 6 includes a demethanizer 61. The steps for light hydrocarbon recovery are as follows: Cool the purified natural gas and use a liquid hydrocarbon separator to separate the cooled purified natural gas into gaseous and liquid products. Select demethanizer 61, use the gaseous product as the middle feed of demethanizer 61, and the liquid product as the top feed of demethanizer 61. After distillation in demethanizer 61, obtain liquid hydrocarbon products. After obtaining liquid hydrocarbon products, they can be cooled and liquefied as needed, and then stored and transported in a mixed hydrocarbon storage tank.

[0054] Alternatively, after obtaining the mixed hydrocarbon product, an ethane stripper 62, a propane stripper, and a butane stripper 63 can be selected, and the mixed hydrocarbon product can be passed through the ethane stripper 62, the propane stripper, and the butane stripper 63 in sequence to obtain the overhead distillate. After the overhead distillate is throttled and depressurized, an active heat exchanger is used to reheat the throttled and depressurized overhead distillate. At this time, high-purity ethane, propane, and butane are obtained. After mixing according to requirements, it can be introduced into the natural gas pipeline network.

[0055] The purified natural gas is cooled using a mixed refrigerant. Before cooling the purified natural gas, the mixed refrigerant is pressurized and separated using a booster compressor to obtain a gaseous refrigerant and a liquid refrigerant. The gaseous and liquid refrigerants are cooled separately. A flash tank 41 is selected, and the liquid refrigerant is throttled and depressurized before being introduced into the flash tank 41. The gaseous refrigerant is throttled and depressurized before being introduced into the demethanizer 61 to cool the gas in the demethanizer 61. After cooling, the gaseous refrigerant is introduced into the flash tank 41 to merge with the liquid refrigerant. After the merged refrigerant is reheated, it is injected back into the booster compressor to form a closed-loop refrigeration system that continuously cools the purified natural gas (i.e., the gas at the top of the demethanizer 61).

[0056] Compared to existing technologies, this solution reduces the demand for refrigerant during the cooling process through the components of a closed-loop cooling system. At the same time, compared to open-loop cooling systems, this solution has no pollution emissions and lower maintenance costs, resulting in significant economic advantages.

[0057] Simultaneously, the carbon dioxide gas discharged from the deacidification unit 4 is purified. During the purification process, the carbon dioxide is pressurized using compressor 1, and then cooled using a cooler to liquefy the moisture and heavy hydrocarbons. A gas-liquid separator is then used to separate the moisture and heavy hydrocarbons from the carbon dioxide gas, which is subsequently liquefied to obtain liquid carbon dioxide. After separation, the top non-condensable gas can be returned to the outlet of compressor 1 for recycling, which helps to increase the output of this scheme.

[0058] This scheme purifies the carbon dioxide gas discharged from deacidification unit 4, enabling the recovery and utilization of reaction byproducts and improving the economic efficiency of the scheme. Simultaneously, after obtaining liquid carbon dioxide, a carbon dioxide reinjection operation can be performed. Utilizing the liquid carbon dioxide to drive water-based fracturing fluid helps reduce water waste during shale gas extraction and also reduces damage to the formation during extraction. Furthermore, carbon dioxide can compete with methane for adsorption, promoting shale gas release and increasing shale gas production.

[0059] Example 2

[0060] Image attached Figure 3 -Appendix Figure 7As shown, the difference from the above embodiment is that in S3, the deacidification unit 4 includes a first absorption tower 43, a first regeneration tower 42 is sleeved on the outside of the first absorption tower 43, and a plurality of channels 421 are provided inside the first absorption tower 43. The channels 421 are arranged vertically, and both ends of the channels 421 are connected to the first regeneration tower 42. The channels 421 are all spiral-shaped. A heating assembly 44 is installed inside the outer wall of the first regeneration tower 42. The heating assembly 44 is used to heat the first regeneration tower 42. The heating assembly 44 includes a reboiler 441, which is connected to a heat exchange tube 443. The heat exchange tube 443 contains heat transfer oil. The reboiler 441 is used to heat the heat transfer oil. The heat transfer oil is used for... The heat exchange tube 443 is installed on the upper part of the first regeneration tower 42 to transfer heat to the absorbent. The heat exchange tube 443 is also connected to a circulation pump 442, which is used to drive the heat transfer oil to circulate in the heat exchange tube 443. The deacidification unit 4 also includes a control system, which includes an infrared thermal imager and a controller. The reboiler 441, the circulation pump 442 and the infrared thermal imager are all electrically connected to the controller. The infrared imager is used to collect temperature information at various locations in the first regeneration tower 42. The controller judges the temperature distribution of the fluid in the first regeneration tower 42 based on the temperature information and controls the operation of the reboiler 441 and the circulation pump 442 based on the temperature distribution in the first regeneration tower 42.

[0061] The deacidification unit 4 also includes a condensation assembly, which is used to cool the absorbent in the first absorption tower 43. The condensation assembly includes a condenser tube installed in the first absorption tower 43. The condenser tube contains condensate and is connected to a flash tank 41.

[0062] The controller can also obtain the rate of rise of the absorbent liquid level based on the temperature distribution in the first regeneration tower 42, and determine whether there is a leak in the heat exchange tube 443 based on the rate of rise of the absorbent liquid level. When there is a leak in the heat exchange tube 443, the controller shuts down the circulating pump 442 and the reboiler 441.

[0063] The bottom wall of the first absorption tower 43 is connected to the bottom wall of the first regeneration tower 42. The input end of the first absorption tower 43 is connected to a conveying assembly, which includes a lean liquid pump (not shown in the figure). The conveying assembly is used to inject absorbent into the first absorption tower 43 and inject the gas phase of the original shale gas into the first absorption tower 43. The first absorption tower 43 is used to allow the absorbent to react with carbon dioxide in the gas phase and to transfer the heat of reaction to the first regeneration tower 42. The first regeneration tower 42 is used to perform gas stripping regeneration on the absorbent that has absorbed carbon dioxide. The conveying assembly is also used to inject absorbent into the first absorption tower 43 when the lean liquid level of the absorbent in the first regeneration tower 42 reaches a preset value. The input end of the lean liquid pump is connected to the output end of the first regeneration tower 42. The input ends of the first regeneration tower 42 and the first absorption tower 43 are both connected to the output end of the lean liquid pump. Solenoid valves are provided at the connection points between the first regeneration tower 42 and the first absorption tower 43 and the lean liquid pump.

[0064] The specific implementation method is as follows: When using this scheme, the operator opens the solenoid valve corresponding to the connection between the lean liquid pump and the first absorption tower 43, and starts the lean liquid pump at the same time. The lean liquid pump is used to inject the gas phase of the original shale gas into the first absorption tower 43 from the bottom. At the same time, the lean liquid pump is used to inject the absorbent into the first absorption tower 43 from the top. Since the main component of shale gas under normal conditions is methane, and the density of methane is less than that of air, when the gas phase of the original shale gas enters the first absorption tower 43, the gas phase of the original shale gas moves upward, while the absorbent moves downward under the action of gravity. The two converge in the first absorption tower 43. At this time, the absorbent reacts with the carbon dioxide in the gas phase of the original shale gas to capture the carbon dioxide. The other part of the gas phase of the original shale gas leaves the first absorption tower 43 from the top and enters the next processing flow.

[0065] During this process, heat of reaction is generated during the reaction between the absorbent and carbon dioxide. When the absorbent enters the bottom of the first regeneration tower 42 from the bottom of the first absorption tower 43 (at this time, the absorbent after absorbing carbon dioxide is a rich liquid), the surface of the rich liquid gradually moves upward. As the surface of the liquid moves, when the surface of the rich liquid moves to the bottom of the lowest channel 421, under the action of gravity, surface tension of the liquid, etc., the rich liquid enters the channel 421. When the rich liquid enters the first absorption tower 43 through the channel 421, the absorbent radiates heat to the first absorption tower 43 and the external environment during its movement, making the temperature of the rich liquid lower than the temperature of the absorbent in the first absorption tower 43. This allows the rich liquid to help cool down the absorbent in the first absorption tower 43, preventing it from degrading due to excessive temperature caused by the heat of reaction. At the same time, the temperature of the rich liquid also rises.

[0066] In the first absorption tower 43, the carbon dioxide at the top is almost completely reacted, while the absorbent at the bottom is nearing saturation. This results in less intense reactions at the top and bottom of the tower, generating significantly less heat than in the lower middle sections. However, in the first regeneration tower 42, as the rich liquid level moves, the heat gradually diffuses towards the tower wall and the outside, causing the temperature at the rich liquid level to gradually decrease. Thus, as the rich liquid level rises, its temperature also decreases. Therefore, before the rich liquid level reaches the lower middle section of the first absorption tower 43, the cooling effect of the rich liquid on the absorbent gradually increases, adapting to the changing heat of reaction from the bottom to the lower middle sections of the tower. This reduces the probability of decomposition of the absorbent in the most intensely reacting lower middle section of the tower due to the heat of reaction.

[0067] Meanwhile, before the liquid level of the rich liquid rises to the middle and lower part of the first absorption tower 43, the temperature inside the first absorption tower 43 rises in a stepwise manner. As a result, the heat transferred to the rich liquid through the channel 421 also rises in a stepwise manner, thereby achieving preheating for subsequent regeneration of the rich liquid and avoiding the decrease in the stability of the reaction system and the reduction in the activity of the absorbent that may be caused by sudden heating.

[0068] Furthermore, the spiral channel 421 design in this embodiment can further increase the contact area between the channel 421 carrying the hot liquid and the absorbent in the first absorption tower 43, thereby improving the efficiency of heat transfer.

[0069] During this process, the infrared thermal imager works continuously to collect temperature information at various locations in the first regeneration tower 42. As the temperature of the rich liquid gradually changes, there is a certain temperature difference between the surface of the rich liquid and the temperature of the rich liquid. Therefore, based on the temperature values ​​and isotherms, the temperature difference between the upper and lower isotherms is calculated. The isotherm with the largest difference is the surface of the rich liquid.

[0070] When the liquid level of the rich liquid reaches the location of the heat exchange tube 443, the controller controls the reboiler 441 and the circulating pump 442 to gradually increase their working power in order to gradually heat the rich liquid and promote its regeneration.

[0071] Meanwhile, the controller obtains the liquid level of the absorbent based on the temperature distribution and monitors the upward movement speed of the absorbent liquid level. When the speed at which the absorbent enters and leaves the first absorption tower 43 is uniform, the speed at which the absorbent liquid level rises should also be uniform.

[0072] Furthermore, due to the design of the heat exchange tube 443 in this scheme, heat is indirectly transferred between the heat transfer oil and the absorbent. During the heating process, no other substances enter the absorbent. The change in the absorbent liquid level is only caused by the absorbent continuously entering the first regeneration tower 42. If the absorbent liquid level changes abnormally at this time, it may be due to the heat transfer oil entering the first regeneration tower 42 (i.e., the heat exchange tube 443 is leaking). When the absorbent liquid level rises rapidly, it may be due to the absorbent foaming caused by the leak in the heat exchange tube 443. At this time, the controller shuts down the circulating pump 442 and the reboiler 441 to prevent the subsequent heat transfer oil from continuing to enter the first regeneration tower 42, causing absorbent loss and pollution, thereby increasing the implementation cost of the scheme.

[0073] Compared to existing technologies, this solution, through the design of channel 421, fully utilizes the heat of reaction during the absorbent's capture of carbon dioxide and cools the absorbent in the first absorption tower 43 using a rich liquid, reducing energy consumption in the reaction system. Simultaneously, since channel 421 penetrates the first absorption tower 43, the rich liquid can cool the center of the first absorption tower 43, helping to reduce degradation caused by excessively high temperatures in the most reactive areas of the first absorption tower 43. Furthermore, because the viscosity of the absorbent increases after absorbing carbon dioxide, this solution introduces the rich liquid from the bottom of the first regeneration tower 42. Compared to top-entry solutions, this reduces the increased viscosity of the absorbent after carbon dioxide absorption, which causes it to adhere to the sidewalls of the first regeneration tower 42 during flow, hindering the movement of the rich liquid and making it difficult for the rich liquid to enter channel 421 to cool the absorbent in the first absorption tower 43.

[0074] Example 3

[0075] The difference from the above embodiment is that a cooling component 45 is provided on the conveying assembly. The cooling component 45 is used to reduce the temperature of the absorbent entering the first absorption tower 43. The cooling component 45 includes a main pipe 451. The input end of the main pipe 451 is connected to the lean liquid pump, and the output end of the main pipe 451 is connected to the input end of the first absorption tower 43. A branch pipe 452 is provided on any side of the main pipe 451, and both ends of the branch pipe 452 are connected to the side wall of the main pipe 451. A semiconductor cooling chip is installed on the side wall of the branch pipe 452.

[0076] The specific implementation method is as follows: During the use of this solution, when the semiconductor cooling chip is started, as the absorbent enters the main flow tube 451, it is diverted by the branch tube 452 near the connection between the main flow tube 451 and the branch tube 452. Part of the absorbent enters the branch tube 452. At the same time, as the semiconductor cooling chip works, the temperature of the absorbent in the branch tube 452 drops rapidly, and a significant temperature difference appears between it and the absorbent in the main flow tube 451. When the absorbent in the branch tube 452 re-enters the main flow tube 451, it impacts the absorbent in the main flow tube 451. The two streams of absorbent hinder each other, slowing down the flow of absorbent, thereby prolonging the contact time between the semiconductor cooling chip and the absorbent, thus improving the cooling effect.

[0077] Meanwhile, since there is a significant temperature difference between the absorbent in the branch pipe 452 and the main pipe 451, according to the laws of thermodynamics, the greater the temperature difference between substances, the stronger the driving force for heat transfer, and the efficiency of heat conduction, heat convection and heat radiation is significantly improved. This allows the temperatures of the two absorbents to reach equilibrium quickly, thus ensuring that the internal temperature of the absorbent that subsequently re-enters the first absorption tower 43 is uniform. This results in a more stable absorption rate for the absorbent and reduces the thermal degradation that may result from local overheating of the absorbent.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of treatment in relation to shale gas, characterised in that: include: S1: Pressurize the raw shale gas using compressor (1): S2: The pressurized raw shale gas is lightly cooled and separated by a three-phase separator (3) to obtain the gas phase of the raw shale gas and reheat the gas phase temperature of the raw shale gas. S3: Select the deacidification unit (4), use an absorbent to decarbonize the gas phase of the reheated original shale gas through the deacidification unit (4), and produce carbon dioxide; S4: Select a dehydration unit (5). The dehydration unit (5) includes three sets of adsorption towers (51), and each adsorption tower (51) is equipped with an adsorbent. Inject the gas phase of the original shale gas after decarbonization treatment into any set of adsorption towers (51) for dehydration treatment. Introduce circulating regeneration gas into any set of adsorption towers (51) of the remaining two sets of adsorption towers (51). The heat in the set of adsorption towers (51) enters the circulating regeneration gas. Then, heat the circulating regeneration gas and inject the heated circulating regeneration gas into the last set of adsorption towers (51). Heat the adsorbent in the set of adsorption towers (51) for desorption. Repeat the above steps until all the decarbonized gas phases are dehydrated to obtain purified natural gas. S5: Select the light hydrocarbon recovery unit (6), use the light hydrocarbon recovery unit (6) to recover the light hydrocarbons in the purified natural gas, and purify the carbon dioxide discharged from the deacidification unit (4) to obtain liquid carbon dioxide; In S3, the deacidification unit (4) includes a first absorption tower (43), and a first regeneration tower (42) is fitted outside the first absorption tower (43). The first absorption tower (43) is provided with several channels (421), the channels (421) are arranged vertically, and both ends of the channels (421) are connected to the first regeneration tower (42). A heating component (44) is installed inside the outer wall of the first regeneration tower (42). The heating component (44) is used to heat the first regeneration tower (42). The bottom wall of the first absorption tower (43) is connected to the bottom wall of the first regeneration tower (42). The input end of the first absorption tower (43) is connected to a conveying component. The conveying component is used to inject absorbent into the first absorption tower (43) and inject the gas phase of the original shale gas into the first absorption tower (43). The first absorption tower (43) is used to allow the absorbent to react with carbon dioxide in the gas phase and to transfer the heat of reaction to the first regeneration tower (42). The first regeneration tower (42) is used to perform gas stripping regeneration of the absorbent that absorbs carbon dioxide. The conveying component is also used to inject absorbent into the first absorption tower (43) when the lean liquid degree of the absorbent in the first regeneration tower (42) reaches a preset value. The heating assembly (44) includes a reboiler (441) connected to a heat exchange tube (443). The heat exchange tube (443) contains heat transfer oil. The reboiler (441) heats the heat transfer oil, which then transfers heat to the absorbent. A circulation pump (442) is also connected to the heat exchange tube (443), which drives the heat transfer oil to circulate within the heat exchange tube (443). The deacidification unit (4) also includes a control system, which collects data from various points on the first regeneration tower (42). The system obtains the temperature information of the set temperature, judges the temperature distribution of the fluid in the first regeneration tower (42) based on the temperature information, and controls the operation of the reboiler (441) and the circulating pump (442) based on the temperature distribution in the first regeneration tower (42). The system obtains the absorbent liquid level rise rate based on the temperature distribution in the first regeneration tower (42), and judges whether the heat exchange tube (443) is leaking based on the absorbent liquid level rise rate. When the heat exchange tube (443) is leaking, the system shuts down the circulating pump (442) and the reboiler (441).

2. The method for processing shale gas according to claim 1, characterized in that: In step S4, before injecting the gas phase of the decarbonized raw shale gas into any set of adsorption towers (51), the gas phase of the raw shale gas is divided into two parts, and any one part is selected and passed into the adsorption tower (51) for dehydration treatment. The other part of the raw shale gas gas is used as circulating regeneration gas and enters the set of adsorption towers (51) that are being cooled to absorb the heat in the set of adsorption towers (51). Then, the gas phase is heated and after the heating is completed, it is passed into the last set of adsorption towers (51) for heating treatment. After the heating treatment is completed, the gas phase is cooled using a cooler (55), and the liquid phase in the gas phase of the raw shale gas is removed using a gas-liquid separator (56). The gas phase of the raw shale gas is then mixed with the gas phase of the other raw shale gas to complete the dehydration treatment of the gas phase of the raw shale gas after decarbonization treatment.

3. The method for processing shale gas according to claim 1, characterized in that: In S5, the light hydrocarbon recovery unit (6) includes a demethanizer (61). The steps for light hydrocarbon recovery are as follows: the purified natural gas is cooled and the cooled purified natural gas is separated into gas and liquid by a liquid hydrocarbon separator to obtain gas products and liquid products. The demethanizer (61) is selected, and the gas products are used as the middle feed of the demethanizer (61) and the liquid products are used as the top feed of the demethanizer (61). After the distillation of the demethanizer (61), a mixed liquid hydrocarbon product is obtained.

4. A method for processing shale gas according to claim 3, characterized in that: In step S5, after obtaining the mixed liquid hydrocarbon product, an ethane removal tower (62), a propane removal tower, and a butane removal tower (63) are selected, and the mixed liquid hydrocarbon product is passed through the ethane removal tower (62), the propane removal tower, and the butane removal tower (63) in sequence to obtain the top distillate gas. After the top distillate gas is throttled and depressurized, an active heat exchanger is used to reheat the top distillate gas after throttled and depressurized treatment.

5. A method for processing shale gas according to claim 4, characterized in that: In S5, a mixed refrigerant is used to cool the purified natural gas. Before cooling the purified natural gas, a booster is used to pressurize and separate the mixed refrigerant to obtain a gaseous refrigerant and a liquid refrigerant. The gaseous refrigerant and the liquid refrigerant are cooled separately, and a flash tank (41) is selected. The liquid refrigerant is throttled and depressurized and then introduced into the flash tank (41). The gaseous refrigerant is throttled and depressurized and then introduced into the demethanizer (61) to cool the gas in the demethanizer (61). After cooling, the gaseous refrigerant is introduced into the flash tank (41) to merge with the liquid refrigerant. After the merged refrigerant is reheated, the refrigerant is injected into the booster again.

6. A method for processing shale gas according to claim 1, characterized in that: The absorbent used in S3 is a complex amine.

7. A method for processing shale gas according to claim 1, characterized in that: A cooling component (45) is provided on the conveying assembly. The cooling component (45) is used to reduce the temperature of the absorbent entering the first absorption tower (43). The cooling component (45) includes a main pipe (451). The input end of the main pipe (451) is connected to the conveying assembly, and the output end of the main pipe (451) is connected to the input end of the first absorption tower (43). A branch pipe (452) is provided on any side of the main pipe (451), and both ends of the branch pipe (452) are connected to the side wall of the main pipe (451). A semiconductor cooling chip is installed on the side wall of the branch pipe (452).

Images