Recovery system and method for triethylene glycol regeneration waste gas

Abstract

The invention discloses a system and a method for recycling triethylene glycol regenerated waste gas. The system comprises a lean-rich liquid heat exchanger, a pretreatment device, a rich liquid regenerator and a waste gas treatment device, the rich solution regenerator is used for heating the received triethylene glycol rich solution; the pretreatment device, the lean and rich solution heat exchanger and the rich solution regenerator form a closed loop path, the pretreatment device receives the heated triethylene glycol rich solution and performs flash evaporation and filtration treatment on the heated triethylene glycol rich solution, so that the heated triethylene glycol rich solution reaches a preset rectification condition, and the triethylene glycol rich solution reaching the rectification condition flows through the lean and rich solution heat exchanger and then flows through the lean and rich solution regenerator; feeding into a rich solution regenerator for rectification treatment to obtain a triethylene glycol barren solution and regenerated waste gas; and the waste gas treatment device is connected with the rich liquid regenerator, receives the regenerated waste gas, performs condensation and pressurization treatment on the regenerated waste gas, generates water and first fuel gas, and sprays out the first fuel gas. Energy consumption can be reduced, pollution of regenerated waste gas to the environment is effectively eliminated, and zero emission of the natural gas solvent absorption dehydration process is achieved.

Description

Technical Field

[0001] The present invention relates to the field of waste gas treatment, and particularly to a recovery system and method for the regeneration waste gas of triethylene glycol. Background Art

[0002] In the process of natural gas dehydration, the process of using triethylene glycol solution to dehydrate natural gas is simple. Among them, the triethylene glycol solution can be regenerated at atmospheric pressure, is convenient for operation and maintenance, and the processing scale of the process device has a large elasticity and a wide adaptation range to changes in gas quality conditions. Therefore, it is most widely used in dehydration treatment. However, in the process of regenerating the triethylene glycol solution in the triethylene glycol dehydration process, regeneration waste gas is generated. If the regeneration waste gas is directly discharged, it will pollute the environment, and the regeneration waste gas has a strong odor. If the regeneration waste gas is incinerated, it will cause waste of fuel and increase in carbon emissions, and will also increase the factory operation cost and equipment investment. To solve the problem of discharging the regeneration waste gas, the existing technology introduces the regeneration waste gas into the reboiler at the lower part of the triethylene glycol regenerator and directly uses it as fuel. However, this method has the following disadvantages, resulting in unstable operation of the burner: 1. Due to the high water vapor content in the regeneration waste gas, the burner often has problems of flameout or water dripping; 2. The change in the stripping gas volume has a very obvious impact on the fuel gas volume.

[0003] In addition, in the process of regenerating the triethylene glycol solution, the triethylene glycol rich solution enters the top coil of the triethylene glycol regenerator. The top coil of the existing technology mainly adopts the inner coil type, which not only has low heat exchange efficiency, but also the outlet temperature is uncontrollable. If the outlet temperature is too high, the triethylene glycol component carried by the flash gas increases, resulting in an increase in the loss of the triethylene glycol solution; if the temperature is too low, it is not conducive to the flash separation of non-condensable gas. In addition, the filtration process of the triethylene glycol solution during regeneration is complex and there are many filtration devices, which is not conducive to the integration of the device.

[0004] Therefore, it is very necessary to provide a triethylene glycol regeneration integrated device that solves the problems of difficult recovery and utilization of triethylene glycol regeneration waste gas, and complex filtration and large loss of triethylene glycol regeneration solution. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a recovery system and method for the regeneration waste gas of triethylene glycol that overcomes the above problems or at least partially solves the above problems.

[0006] In a first aspect, an embodiment of the present invention provides a recovery system for triethylene glycol regeneration waste gas, including a rich and lean liquid heat exchanger, and further including: a pretreatment device, a rich liquid regenerator, and a waste gas treatment device;

[0007] The rich liquid regenerator is used to heat the received triethylene glycol rich liquid;

[0008] The pre-treatment device, the lean-rich liquid heat exchanger, and the rich liquid regenerator form a closed-loop path. The pre-treatment device is used to receive the heated triethylene glycol rich liquid, and perform flash evaporation and filtration on the heated triethylene glycol rich liquid, so that the heated triethylene glycol rich liquid meets the preset rectification conditions. After the triethylene glycol rich liquid that meets the rectification conditions flows through the lean-rich liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regenerated waste gas;

[0009] The waste gas treatment device is connected to the rich liquid regenerator, and is used to receive the regenerated waste gas, and perform condensation and pressurization treatment on the regenerated waste gas to generate water and first fuel gas, and eject the first fuel gas.

[0010] In one embodiment, the waste gas treatment device includes a waste gas cooling and separation unit and an ejector waste gas device;

[0011] The waste gas cooling and separation unit is respectively connected to the rich liquid regenerator and the ejector waste gas device. The waste gas cooling and separation unit is used to receive the regenerated waste gas and perform condensation treatment on the regenerated waste gas to obtain second fuel gas;

[0012] The ejector waste gas device is used to receive the second fuel gas, perform pressurization treatment on the second fuel gas to generate first fuel gas, and eject the first fuel gas. The pressure of the second fuel gas is lower than that of the first fuel gas.

[0013] In one embodiment, the rich liquid regenerator includes a rich liquid heater and a rectification column;

[0014] The rich liquid heater is respectively connected to the pre-treatment device, the rectification column, and the waste gas cooling and separation unit. The rich liquid heater is used to heat the received triethylene glycol rich liquid;

[0015] The rectification column is also connected to the lean-rich liquid heat exchanger; the rectification column is used to receive the triethylene glycol rich liquid that meets the rectification conditions, and perform rectification treatment on the triethylene glycol rich liquid that meets the rectification conditions to obtain triethylene glycol lean liquid and regenerated waste gas. After the regenerated waste gas flows through the rich liquid heater, it enters the waste gas cooling and separation unit.

[0016] In one embodiment, the rich liquid heater adopts a tube bundle heat exchanger.

[0017] In one embodiment, the pre-treatment device includes a rich liquid flash tank and a filter skid;

[0018] One end of the rich liquid flash tank is connected to the rich liquid heater, and is used to receive the heated triethylene glycol rich liquid and perform flash evaporation on the received heated triethylene glycol rich liquid;

[0019] The other end of the rich liquid flash tank is connected to the filtration skid, and is used to receive the triethylene glycol rich liquid after gas-liquid separation and filter the triethylene glycol rich liquid after gas-liquid separation.

[0020] In one embodiment, the filtration skid includes a first mechanical filter element, activated carbon, and a second mechanical filter element, and the first mechanical filter element, activated carbon, and second mechanical filter element are integrally integrated.

[0021] In one embodiment, the lean-rich liquid heat exchanger is further used to be connected to the bottom of the rich liquid regenerator to receive the triethylene glycol lean liquid.

[0022] In one embodiment, a three-way valve is arranged between the pretreatment device and the rich liquid regenerator, and the three-way valve is used to control the temperature of the triethylene glycol rich liquid.

[0023] In a second aspect, an embodiment of the present invention provides a natural gas dehydration treatment system, including a raw gas filtration unit, a dehydration absorption tower, a dry gas-lean liquid heat exchanger, a dry gas coalescing and liquid separation unit, and a lean liquid circulation pump group, characterized in that it further includes the aforementioned triethylene glycol regeneration waste gas recovery device:

[0024] The dehydration absorption tower, the triethylene glycol regeneration waste gas recovery device, the lean liquid circulation pump group, and the dry gas-lean liquid heat exchanger form a closed loop;

[0025] The raw gas filtration unit is used to receive natural gas and filter the natural gas raw material;

[0026] The dehydration absorption tower is connected to the raw gas filtration unit and is used to receive the filtered natural gas, so that the triethylene glycol lean liquid inside dehydrates the filtered natural gas to obtain triethylene glycol rich liquid and dehydrated natural gas;

[0027] The triethylene glycol regeneration waste gas recovery device is connected to the dehydration absorption tower, and the triethylene glycol regeneration waste gas recovery device is used to receive the triethylene glycol rich liquid and perform dehydration regeneration treatment on the triethylene glycol rich liquid to generate triethylene glycol lean liquid and a first raw gas;

[0028] The dry gas-lean liquid heat exchanger is respectively connected to the dehydration absorption tower and the dry gas coalescing and liquid separation unit, and is used to receive the dehydrated natural gas and perform heat exchange treatment on the dehydrated natural gas. The heat-exchanged natural gas enters the dry gas coalescing and liquid separation unit, and the dry gas coalescing and liquid separation unit is used to perform coalescing and liquid separation treatment on the heat-exchanged natural gas; the dry gas-lean liquid heat exchanger is further used to receive triethylene glycol lean liquid, and the triethylene glycol lean liquid enters the dehydration absorption tower;

[0029] The lean liquid circulation pump group is respectively connected to the triethylene glycol regeneration waste gas recovery device and the dry gas-lean liquid heat exchanger.

[0030] In a third aspect, an embodiment of the present invention provides a method for recovering the regenerated waste gas of triethylene glycol. The method is implemented through the aforementioned triethylene glycol regenerated waste gas recovery system, and includes:

[0031] The rich liquid regenerator receives the triethylene glycol rich liquid and heats the triethylene glycol rich liquid.

[0032] The pretreatment device receives the heated triethylene glycol rich liquid, performs flash evaporation and filtration on the heated triethylene glycol rich liquid, so that the heated triethylene glycol rich liquid meets the preset rectification conditions. After the triethylene glycol rich liquid that meets the rectification conditions flows through the rich and lean liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regenerated waste gas.

[0033] The waste gas treatment device receives the regenerated waste gas, condenses and pressurizes the regenerated waste gas to generate water and first fuel gas, and ejects the first fuel gas.

[0034] In a fourth aspect, an embodiment of the present invention provides a method for dehydrating natural gas. The method is implemented through the aforementioned natural gas dehydration treatment system, and includes:

[0035] The raw gas filtration unit receives natural gas and filters the natural gas raw material.

[0036] The dehydration absorption tower receives the filtered natural gas, so that the triethylene glycol lean liquid inside dehydrates the filtered natural gas to obtain triethylene glycol rich liquid and dehydrated natural gas.

[0037] The triethylene glycol regenerated waste gas recovery device receives the triethylene glycol rich liquid and performs dehydration and regeneration treatment on the triethylene glycol rich liquid to generate triethylene glycol lean liquid and first raw gas.

[0038] The dry gas-lean liquid heat exchanger receives the dehydrated natural gas and performs heat exchange on the dehydrated natural gas. The heat-exchanged natural gas enters the dry gas coalescing and liquid separation unit; the dry gas coalescing and liquid separation unit performs coalescing and liquid separation treatment on the heat-exchanged natural gas.

[0039] The dry gas-lean liquid heat exchanger receives triethylene glycol lean liquid, and the triethylene glycol lean liquid enters the dehydration absorption tower.

[0040] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0041] The triethylene glycol regeneration waste gas recovery system provided by the embodiment of the present invention includes a lean-rich liquid heat exchanger, a pretreatment device, a rich liquid regenerator, and a waste gas treatment device; the pretreatment device, the lean-rich liquid heat exchanger, and the rich liquid regenerator form a closed-loop path. The rich liquid regenerator is used to receive the triethylene glycol rich liquid and heat-treat the triethylene glycol rich liquid. The pretreatment device is used to receive the heated triethylene glycol rich liquid and perform flash evaporation and filtration on the heated triethylene glycol rich liquid to make the heated triethylene glycol rich liquid meet the preset rectification conditions. After the triethylene glycol rich liquid meeting the rectification conditions flows through the lean-rich liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regeneration waste gas. The pretreatment device can flash off methane and various hydrocarbon substances dissolved in the triethylene glycol rich liquid, and the flashed methane and various hydrocarbon substances can be used as fuel and enter the whole-plant fuel gas system; the waste gas treatment device is connected to the rich liquid regenerator and is used to receive the regeneration waste gas and perform condensation and pressurization treatment on the regeneration waste gas to generate water and first fuel gas, and eject the first fuel gas. An exhaust gas treatment device is arranged at the outlet of the rich liquid regenerator, and the exhaust gas treatment device is used to condense the regeneration waste gas at the outlet of the rich liquid regenerator, so that the liquid in the regeneration waste gas is condensed and separated, reducing the influence of the liquid on the fuel quality; the exhaust gas treatment device is used to pressurize the regeneration waste gas at the outlet of the rich liquid regenerator, ejecting the separated regeneration waste gas to a high-pressure state, and the regeneration waste gas enters the whole-plant fuel gas system and can be used as fuel for the whole plant. It solves the problem of waste gas emission during the regeneration of triethylene glycol, realizes the recovery and utilization of the regeneration waste gas, reduces the energy consumption required for incinerating the regeneration waste gas, effectively eliminates the pollution of the regeneration waste gas to the surrounding environment, saves the regeneration waste gas incineration facility, reduces the regeneration waste gas emission, and achieves the purpose of energy conservation and emission reduction.

[0042] In addition, the filter skid used in the triethylene glycol regeneration waste gas recovery system provided by the embodiment of the present invention includes a first mechanical filter element, activated carbon, and a second mechanical filter element. The first mechanical filter element, activated carbon, and second mechanical filter element are an integrated filter. Compared with the filters used in the prior art, it can effectively remove pipeline rust slag, triethylene glycol degradation products, and other solid impurities. It simplifies the filtration process, reduces the number of equipment, saves valves and pipelines, and is conducive to the skid-mounted, modular, and integrated layout of the filtration system.

[0043] And the rich liquid heater adopts the form of a tube bundle heat exchanger. Compared with the traditional inner coil type, the tube bundle heat exchanger has high heat transfer efficiency, is easy to control the outlet temperature, and utilizes the flash separation of non-condensable gas.

[0044] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the written specification, claims, and drawings.

[0045] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0046] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0047] Figure 1 is a schematic structural diagram of a triethylene glycol regeneration waste gas recovery system in an embodiment of the present invention;

[0048] Figure 2 is one of the schematic structural diagrams of a natural gas dehydration treatment system in an embodiment of the present invention;

[0049] Figure 3 is another schematic structural diagram of a natural gas dehydration treatment system in an embodiment of the present invention;

[0050] Figure 4 is yet another schematic structural diagram of a natural gas dehydration treatment system in an embodiment of the present invention;

[0051] Figure 5 is a flowchart of a method for recovering triethylene glycol regeneration waste gas in an embodiment of the present invention;

[0052] Figure 6 is a flowchart of a natural gas dehydration method in an embodiment of the present invention;

[0053] Description of the Reference Numerals:

[0054] 101 - rich liquid flash tank; 102 - filter skid; 103 - rich and lean liquid heat exchanger; 104 rich liquid heater; 105 distillation column; 106 - waste gas cooling and separation unit; 107 - ejector waste gas device; 201 - raw gas filtration unit; 202 - dehydration absorption tower; 203 - dry natural gas - lean liquid heat exchanger; 204 - lean liquid circulation pump; 205 - dry gas coalescing and liquid separation unit. Detailed Embodiments

[0055] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0056] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] The inventors of the present invention have found that since the triethylene glycol dehydration process is simple, the triethylene glycol solution can be regenerated at normal pressure, and the operation and maintenance are convenient, the process equipment has a large processing scale flexibility, and the adaptability to changes in gas quality conditions is wide, so it is widely used in natural gas dehydration treatment. However, the regeneration waste gas generated during the regeneration of triethylene glycol has a strong odor and cannot be discharged directly. At present, a gas incinerator is used to incinerate the regeneration waste gas before discharging it into the atmosphere. However, incineration of the regeneration waste gas, on the one hand, causes fuel waste, increases carbon emissions and factory operating costs, and on the other hand, increases the investment in incineration equipment. In order to effectively utilize the regeneration waste gas, the current technology introduces the regeneration waste gas into the reboiler of the triethylene glycol regenerator (rich liquid regenerator) and uses it directly as fuel. However, due to the high water vapor content in the regeneration waste gas, the reboiler often has problems such as flameout or "puff, puff" dripping. At the same time, the change of gas lift gas volume has a very obvious impact on the fuel gas volume. These problems make the reboiler unable to operate stably. In addition, during the regeneration of triethylene glycol, the triethylene glycol rich liquid enters the top coil of the rich liquid regenerator and is heated. The current top coil generally adopts an inner coil type, which has the disadvantages of low heat exchange efficiency and uncontrollable outlet temperature. If the outlet temperature is too high, it is easy to cause an increase in the triethylene glycol carried by the flash gas and increase the solution loss. If the outlet temperature is too low, the non-condensable gas flash separation is not used. In addition, the process of filtering the triethylene glycol rich liquid is complicated and requires many equipments, which is not conducive to the integration of the triethylene glycol dehydration device.

[0059] Based on the above problems, the embodiment of the present invention provides a recovery system of triethylene glycol regeneration waste gas, the structure of which is as follows: Figure 1As shown, it includes: a rich / lean liquid heat exchanger 103, a pretreatment device, a rich liquid regenerator, and an exhaust gas treatment device. In the assembled state of the system:

[0060] The rich liquid regenerator is used to heat the received triethylene glycol rich liquid.

[0061] The pretreatment device, the rich / lean liquid heat exchanger 103, and the rich liquid regenerator form a closed-loop path. The pretreatment device is used to receive the heated triethylene glycol rich liquid and perform flash evaporation and filtration on the heated triethylene glycol rich liquid, so that the heated triethylene glycol rich liquid meets the preset rectification conditions. After the triethylene glycol rich liquid that meets the rectification conditions flows through the rich / lean liquid heat exchanger 103, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regenerated exhaust gas.

[0062] The exhaust gas treatment device is connected to the rich liquid regenerator and is used to receive the regenerated exhaust gas, and perform condensation and pressurization treatment on the regenerated exhaust gas to generate water and a first fuel gas, and eject the first fuel gas.

[0063] In this system, an exhaust gas treatment device is provided. The exhaust gas treatment device is connected to the rich liquid regenerator, receives the regenerated exhaust gas at the outlet of the rich liquid regenerator, performs condensation and pressurization treatment on the regenerated exhaust gas, condenses the water vapor in the regenerated exhaust gas to obtain a first fuel gas. The first fuel gas is pressurized and sprayed outside the system for use as fuel, solving the problem that the reboiler cannot operate stably caused by directly recycling the regenerated exhaust gas, realizing the efficient recycling of the regenerated exhaust gas. This system eliminates the exhaust gas incineration facility, reduces the energy consumption required for incinerating and discharging the regenerated exhaust gas, and at the same time reduces exhaust gas emissions and effectively eliminates the pollution of the regenerated exhaust gas to the surrounding environment.

[0064] In some alternative embodiments, the exhaust gas treatment device includes an exhaust gas cooling and separation unit 106 and an ejector exhaust gas device 107. The exhaust gas cooling and separation unit 106 is respectively connected to the rich liquid regenerator and the ejector exhaust gas device 107. The exhaust gas cooling and separation unit 106 is used to receive the regenerated exhaust gas and perform condensation treatment on the regenerated exhaust gas to obtain a second fuel gas. The ejector exhaust gas device 107 is used to receive the second fuel gas, perform pressurization treatment on the second fuel gas to generate a first fuel gas, and eject the first fuel gas. The pressure of the second fuel gas is lower than that of the first fuel gas.

[0065] Specifically, one end of the waste gas cooling and separation unit 106 is connected to the rich liquid regenerator, and the other end of the waste gas cooling and separation unit 106 is connected to the waste gas ejecting device 107. The waste gas cooling and separation unit 106 is used to receive the regenerated waste gas from the outlet of the rich liquid regenerator, cool the regenerated waste gas to a preset temperature, optionally, cool it to 40 - 50 °C, and separate the liquid in the cooled regenerated waste gas to obtain the first fuel gas. The waste gas ejecting device 107 is used to receive the first fuel gas, and use high-pressure natural gas in the waste gas ejecting device 107 to eject the regenerated waste gas to a preset pressure, for example, eject it to 500 kPa - 600 kPa. The pressurized first fuel gas is ejected to the outside of the system and enters the plant-wide fuel gas system for use as fuel throughout the plant.

[0066] The waste gas cooling and separation unit 106 includes a waste gas cooler (not shown in the figure) and a waste gas liquid separation tank (not shown in the figure);

[0067] The waste gas cooler is respectively connected to the waste gas liquid separation tank and the rich liquid regenerator. The waste gas cooler is used to receive the regenerated waste gas from the outlet of the rich liquid regenerator and cool the regenerated waste gas to a preset temperature;

[0068] The waste gas liquid separation tank is also connected to the waste gas ejecting device 107. The waste gas liquid separation tank is used to receive the cooled regenerated waste gas and separate the liquid in the cooled regenerated waste gas to obtain the first fuel gas. The separated liquid enters the downstream sewage treatment unit, and the first fuel gas enters the waste gas ejecting device 107.

[0069] The pretreatment device includes a rich liquid flash tank 101 and a filter skid 102, and the rich liquid flash tank 101 and the filter skid 102 are connected in sequence;

[0070] The rich liquid regenerator includes a rich liquid heater 104, a distillation column 105 and a reboiler. The rich liquid heater 104, the distillation column 105 and the reboiler are connected in sequence. Still referring to Figure 1 as shown, the rich liquid heating is integrated at the top of the rich liquid regenerator, and the type is a tube bundle heat exchanger. Compared with the traditional heat exchanger with an internal coil, the tube bundle heat exchanger has a higher heat transfer efficiency.

[0071] Among them, the rich liquid heater 104 is also connected to the dehydration absorption tower, the rich liquid flash tank 101 and the waste gas cooling and separation unit 106 respectively. The rich liquid heater 104 is used to receive the triethylene glycol rich liquid that needs to be regenerated (the triethylene glycol rich liquid that needs to be regenerated comes from the dehydration absorption tower). The triethylene glycol rich liquid that needs to be regenerated exchanges heat in the rich liquid heater 104, and its temperature rises. Then it enters the rich liquid flash tank 101 from the rich liquid heater 104. In order to solve the problem that the temperature of triethylene glycol at the outlet of the existing rich liquid heater 104 is uncontrollable, a three-way valve is set at the inlet of the rich liquid heater 104 to adjust and control the temperature of the triethylene glycol rich liquid, preventing the outlet temperature from being too high or too low. If the outlet temperature is too high, the amount of triethylene glycol carried by the flash vapor generated in the rich liquid flash tank 101 will increase, and the solution loss will increase; if the outlet temperature is too low, it is not conducive to the flash separation of non-condensable gas. By controlling the outlet temperature of the rich liquid heater 104 with the three-way valve, the above problems of too high or too low outlet temperature are solved.

[0072] The rich liquid flash tank 101 is used to receive the triethylene glycol rich liquid whose temperature has been raised by heat exchange, flash off methane and various hydrocarbon substances dissolved in the triethylene glycol rich liquid, and obtain the flash vapor (i.e., methane and various hydrocarbon substances) and the triethylene glycol rich liquid after flash treatment. Among them, the flash vapor can be used as low-pressure fuel and directly enter the whole plant fuel gas system. Due to the control of the outlet temperature of the rich liquid heater 104, the flash vapor does not contain triethylene glycol substances, reducing the loss of triethylene glycol solution, and at the same time obtaining purer low-pressure fuel gas.

[0073] The filter skid 102 is used to receive the triethylene glycol rich liquid at the outlet of the rich liquid flash tank 101 and filter the received triethylene glycol rich liquid. The filter skid 102 includes a first mechanical filter element, activated carbon and a second mechanical filter element, and the first mechanical filter element, activated carbon and the second mechanical filter element are integrally integrated. Compared with the traditional filter skid 102, it can effectively remove pipeline rust slag, triethylene glycol degradation products and other solid impurities, and obtain a purer triethylene glycol rich liquid that meets the rectification conditions.

[0074] The triethylene glycol rich liquid that meets the rectification conditions enters the lean-rich liquid heat exchanger 103 for preliminary heat exchange and temperature rise. The triethylene glycol rich liquid after temperature rise enters the rectification column 105, and the rectification column rectifies the received triethylene glycol rich liquid to improve the triethylene glycol rich liquid, enabling the regeneration of triethylene glycol, obtaining triethylene glycol lean liquid, and generating regeneration waste gas. The regeneration waste gas rises and is discharged to the waste gas cooling and separation unit 106 through the outlet of the rich liquid heater 104. In other words, the pretreatment device, the lean-rich liquid heat exchanger 103 and the rich liquid regenerator form a closed-loop path, which is specifically realized by connecting the rich liquid heater 104, the rich liquid flash tank 101, the filter skid 102, the lean-rich liquid heat exchanger 103 and the rectification column 105 to form a closed-loop path. During the regeneration process of triethylene glycol, the help of stripping gas is still required. Still refer to Figure 1As shown, the stripping gas enters the rich liquid regenerator from the component inlet below the rectification column 105, and then enters the rectification column 105 to participate in the triethylene glycol regeneration process.

[0075] It should be noted that during the upward movement of the regeneration waste gas, heat exchange occurs with the rich triethylene glycol liquid in the top tube bundle of the rich liquid heater 104, causing the temperature of the rich triethylene glycol liquid in the tube bundle to rise. Correspondingly, the temperature of the regeneration waste gas drops. The waste heat of the rising regeneration waste gas in the rich liquid regenerator is used to heat the rich triethylene glycol liquid in the tube bundle, while providing cooling at the top of the rich liquid regenerator and recovering part of the evaporated triethylene glycol solution. Combining with the three-way valve set on the inlet and outlet pipelines of the rich liquid heater 104, the temperature of the rich triethylene glycol liquid is adjusted and controlled, so that the temperature of the rich triethylene glycol liquid is heated from 30 - 40 °C at the outlet of the rich liquid heater 104 to about 50 - 60 °C, further ensuring that the rich triethylene glycol liquid entering the rich liquid flash tank 101 maintains an appropriate rich liquid flash temperature.

[0076] In addition, the regenerated lean triethylene glycol liquid is discharged from the bottom outlet of the rich liquid regenerator and can be used in the natural gas dehydration treatment process.

[0077] Based on the same inventive concept, an embodiment of the present invention also provides a natural gas dehydration treatment system, the structure of which is as Figure 2 shown, including: a raw gas filtration unit 201, a dehydration absorption tower 202, a dry gas - lean liquid heat exchanger 203, a dry gas coalescing and liquid - separating unit 205, a lean liquid circulation pump group 204, and the aforementioned triethylene glycol regeneration waste gas recovery device. In the assembled state of the system:

[0078] The dehydration absorption tower 202, the triethylene glycol regeneration waste gas recovery device, the lean liquid circulation pump group 204, and the dry gas - lean liquid heat exchanger 203 form a closed - loop circuit;

[0079] The raw gas filtration unit 201 is used to receive natural gas and filter the natural gas raw material;

[0080] The dehydration absorption tower 202 is connected to the raw gas filtration unit 201 and is used to receive the filtered natural gas, so that the internal lean triethylene glycol liquid dehydrates the filtered natural gas to obtain rich triethylene glycol liquid and dehydrated natural gas;

[0081] The triethylene glycol regeneration waste gas recovery device is connected to the dehydration absorption tower 202. The triethylene glycol regeneration waste gas recovery device is used to receive the rich triethylene glycol liquid and perform dehydration and regeneration treatment on the rich triethylene glycol liquid to generate lean triethylene glycol liquid and a first raw gas;

[0082] The dry gas-lean liquid heat exchanger 203 is connected to the dehydration absorption tower 202 and the dry gas coalescing and liquid separating unit 205 respectively, and is used to receive the dehydrated natural gas and perform heat exchange treatment on the dehydrated natural gas. The natural gas after heat exchange enters the dry gas coalescing and liquid separating unit 205, and the dry gas coalescing and liquid separating unit 205 is used to perform pressurization treatment on the natural gas after heat exchange; the dry gas-lean liquid heat exchanger 203 is also used to receive the triethylene glycol lean liquid, and the triethylene glycol lean liquid enters the dehydration absorption tower 202;

[0083] The lean liquid circulation pump group 204 is connected to the triethylene glycol regeneration waste gas recovery device and the dry gas-lean liquid heat exchanger 203 respectively.

[0084] To illustrate the working process of the natural gas dehydration treatment system more clearly, specific embodiments are used to illustrate the working process of the natural gas dehydration treatment system:

[0085] Embodiment 1:

[0086] Still referring to Figure 2 the structural schematic diagram of the natural gas dehydration treatment system shown, the rich liquid enters the rich liquid heater 104 embedded in the top of the rich liquid regenerator, exchanges heat with the waste gas rising in the rich liquid regenerator, and the temperature of the rich liquid is adjusted and controlled by a three-way valve. The rich liquid heated by heat exchange enters the rich liquid flash tank 101, and methane and various hydrocarbons dissolved in the solution are flashed out. The solution at the bottom outlet of the rich liquid flash tank 101 enters the filter skid 102, and after effectively removing pipeline rust slag, triethylene glycol degradation products and other solid impurities, it enters the rich liquid regenerator for heating and regeneration. The waste gas at the top of the regenerator exchanges heat with the rich liquid in the embedded rich liquid heater at the top, and the waste gas at the outlet of the regenerator enters the waste gas cooler and is cooled to 40-50 °C. The cooled waste gas enters the waste gas liquid separation tank, the separated liquid enters the downstream sewage treatment unit, and the waste gas at the upper outlet directly enters the high-pressure injection device. The waste gas is injected to 500-600 kPa by using high-pressure natural gas in the injection device, and the waste gas enters the whole plant fuel gas system and can be used as fuel for the whole plant.

[0087] Embodiment 2:

[0088] Referring to Figure 3Schematic diagram of the structure of the natural gas dehydration treatment system shown. The rich liquid enters the rich liquid heater 104 embedded in the top of the rich liquid regenerator, exchanges heat with the waste gas rising in the rich liquid regenerator, and the temperature of the rich liquid is adjusted and controlled by a three-way valve. The rich liquid heated by heat exchange enters the rich liquid flash tank 101, and methane and various hydrocarbons dissolved in the solution are flashed out. The solution at the bottom outlet of the rich liquid flash tank 101 enters the filter skid 102, effectively removes pipeline rust slag, triethylene glycol degradation products and other solid impurities, and then enters the rich liquid regenerator for heating and regeneration. The waste gas at the top of the regenerator exchanges heat with the rich liquid in the embedded rich liquid heater at the top. The waste gas at the outlet of the regenerator enters the waste gas cooler and is cooled to 40 - 50 °C. The cooled waste gas enters the waste gas separation tank, the separated liquid enters the downstream sewage treatment unit, and the waste gas at the upper outlet directly enters the high-pressure injection device. Using fuel gas (pressure about 400 kPa), the waste gas is ejected to 100 kPa in the injection device, and the waste gas enters the reboiler at the lower part of the regenerator as fuel gas to heat the solution, realizing the recycling of waste gas.

[0089] Example 3:

[0090] Reference Figure 4 Schematic diagram of the structure of the natural gas dehydration treatment system shown. The rich liquid enters the rich liquid heater 104 embedded in the top of the rich liquid regenerator, exchanges heat with the waste gas rising in the rich liquid regenerator, and the temperature of the rich liquid is adjusted and controlled by a three-way valve. The rich liquid heated by heat exchange enters the rich liquid flash tank 101, and methane and various hydrocarbons dissolved in the solution are flashed out. The solution at the bottom outlet of the rich liquid flash tank 101 enters the filter skid 102, effectively removes pipeline rust slag, triethylene glycol degradation products and other solid impurities, and then enters the rich liquid regenerator for heating and regeneration. The waste gas at the top of the regenerator exchanges heat with the rich liquid in the embedded rich liquid heater at the top. The waste gas at the outlet of the regenerator enters the waste gas cooler and is cooled to 40 - 50 °C. The cooled waste gas enters the waste gas separation tank, the separated liquid enters the downstream sewage treatment unit, and the waste gas at the upper outlet directly enters the high-pressure injection device. Using low-pressure steam (pressure about 500 kPa), the waste gas is ejected to 50 kPa in the injection device, and the waste gas enters the incinerator of the downstream sulfur recovery unit.

[0091] Based on the same inventive concept, the embodiments of the present invention also provide a method for recovering the regenerated waste gas of triethylene glycol, which is realized by the aforementioned triethylene glycol regenerated waste gas recovery system, and its process reference Figure 5 shown, including the following steps:

[0092] Step S51: The rich liquid regenerator receives the triethylene glycol rich liquid and heats the triethylene glycol rich liquid;

[0093] Step S52: The pre-treatment device receives the heated triethylene glycol rich solution, and performs flash evaporation and filtration on the heated triethylene glycol rich solution, so that the heated triethylene glycol rich solution meets the preset rectification conditions. After the triethylene glycol rich solution that meets the rectification conditions flows through the rich and lean liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean solution and regenerated waste gas;

[0094] Step S53: The waste gas treatment device receives the regenerated waste gas, and performs condensation and pressurization treatment on the regenerated waste gas to generate water and the first fuel gas, and sprays out the first fuel gas.

[0095] Based on the same inventive concept, an embodiment of the present invention further provides a method for dehydrating natural gas, which is implemented by the aforementioned natural gas dehydration treatment system, and its process reference Figure 6 is shown as follows:

[0096] Step S61: The raw gas filtration unit receives natural gas and filters the natural gas raw material;

[0097] Step S62: The dehydration absorption tower receives the filtered natural gas, so that the triethylene glycol lean solution inside dehydrates the filtered natural gas to obtain triethylene glycol rich solution and dehydrated natural gas;

[0098] Step S63: The triethylene glycol regenerated waste gas recovery device receives the triethylene glycol rich solution, and performs dehydration regeneration treatment on the triethylene glycol rich solution to generate triethylene glycol lean solution and the first raw gas;

[0099] Step S64: The dry gas-lean liquid heat exchanger receives the dehydrated natural gas and performs heat exchange treatment on the dehydrated natural gas. The heat-exchanged natural gas enters the dry gas coalescence and liquid separation unit; the dry gas coalescence and liquid separation unit performs coalescence and liquid separation treatment on the heat-exchanged natural gas;

[0100] Step S65: The dry gas-lean liquid heat exchanger receives the triethylene glycol lean solution, and the triethylene glycol lean solution enters the dehydration absorption tower.

[0101] Unless otherwise specifically stated, terms such as processing, calculating, operating, determining, displaying, etc. can refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which will represent the data operation and conversion of physical (such as electronic) quantities in the registers or memories of the processing system into other data that are similarly represented as physical quantities in the memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0102] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy recited.

[0103] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are expressly recited in each claim. Rather, as reflected in the appended claims, the invention lies in less than the full scope of the features of the disclosed single embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0104] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Further, with respect to the term "comprising" used in the specification or claims, this term is inclusive in a manner similar to the term "including" as interpreted when used as a transitional word in a claim. Additionally, any use of the term "or" in the claims or specification is to be meant "non-exclusive or".

Claims

1. A triethylene glycol regeneration waste gas recovery system, comprising a rich and lean liquid heat exchanger, characterized in that, It further includes: A pretreatment device, a rich liquid regenerator, and an exhaust gas treatment device; The rich liquid regenerator is used to heat the received triethylene glycol rich liquid; The pretreatment device, the rich and lean liquid heat exchanger, and the rich liquid regenerator form a closed-loop path. The pretreatment device is used to receive the heated triethylene glycol rich liquid and perform flash evaporation and filtration on the heated triethylene glycol rich liquid, so that the heated triethylene glycol rich liquid meets the preset rectification conditions. After the triethylene glycol rich liquid that meets the rectification conditions flows through the rich and lean liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regenerated exhaust gas; The exhaust gas treatment device is connected to the rich liquid regenerator and is used to receive the regenerated exhaust gas, condense and pressurize the regenerated exhaust gas to generate water and first fuel gas, and eject the first fuel gas.

2. The triethylene glycol regeneration waste gas recovery system according to claim 1, wherein The exhaust gas treatment device includes an exhaust gas cooling and separation unit and an ejector exhaust gas device; The exhaust gas cooling and separation unit is respectively connected to the rich liquid regenerator and the ejector exhaust gas device. The exhaust gas cooling and separation unit is used to receive the regenerated exhaust gas and perform condensation treatment on the regenerated exhaust gas to obtain second fuel gas; The ejector exhaust gas device is used to receive the second fuel gas, pressurize the second fuel gas to generate first fuel gas, and eject the first fuel gas. The pressure of the second fuel gas is lower than that of the first fuel gas.

3. The triethylene glycol regeneration waste gas recovery system according to claim 2, characterized in that, The rich liquid regenerator includes a rich liquid heater and a rectification column; The rich liquid heater is respectively connected to the pretreatment device, the rectification column, and the exhaust gas cooling and separation unit. The rich liquid heater is used to heat the received triethylene glycol rich liquid; The rectification column is also connected to the rich and lean liquid heat exchanger; the rectification column is used to receive the triethylene glycol rich liquid that meets the rectification conditions and perform rectification treatment on the triethylene glycol rich liquid that meets the rectification conditions to obtain triethylene glycol lean liquid and regenerated exhaust gas. After the regenerated exhaust gas flows through the rich liquid heater, it enters the exhaust gas cooling and separation unit.

4. The triethylene glycol regeneration waste gas recovery system according to claim 3, wherein The rich liquid heater adopts a tube bundle heat exchanger.

5. The triethylene glycol regeneration waste gas recovery system according to claim 3, characterized in that, The pretreatment device includes a rich liquid flash tank and a filter skid; One end of the rich liquid flash tank is connected to the rich liquid heater and is used to receive the heated triethylene glycol rich liquid and perform flash evaporation on the received heated triethylene glycol rich liquid; The other end of the rich liquid flash tank is connected to the filter skid and is used to receive the triethylene glycol rich liquid after gas-liquid separation and perform filtration on the triethylene glycol rich liquid after gas-liquid separation.

6. The triethylene glycol regeneration waste gas recovery system according to claim 5, wherein, The filter skid includes a first mechanical filter element, activated carbon, and a second mechanical filter element, and the first mechanical filter element, activated carbon, and second mechanical filter element are integrally integrated.

7. The triethylene glycol regeneration waste gas recovery system according to claim 1, characterized in that, The rich and lean liquid heat exchanger is also used to be connected to the bottom of the rich liquid regenerator to receive triethylene glycol lean liquid.

8. The triethylene glycol regeneration waste gas recovery system according to claim 1, characterized in that, A three-way valve is arranged between the pretreatment device and the rich liquid regenerator, and the three-way valve is used to control the temperature of the triethylene glycol rich liquid.

9. A natural gas dehydration treatment system, comprising a raw gas filtration unit, a dehydration absorption tower, a dry gas - lean liquid heat exchanger, a dry gas coalescence and liquid separation unit, and a lean liquid circulation pump set, characterized in that, It further includes the triethylene glycol regenerated exhaust gas recovery device according to any one of claims 1-8: The dehydration absorption tower, the triethylene glycol regenerated exhaust gas recovery device, the lean liquid circulation pump group, and the dry gas-lean liquid heat exchanger form a closed-loop circuit; The raw gas filtration unit is used to receive natural gas and filter the natural gas raw material; The dehydration absorption tower is connected to the raw gas filtration unit and is used to receive the filtered natural gas, so that the triethylene glycol lean liquid inside dehydrates the filtered natural gas to obtain triethylene glycol rich liquid and dehydrated natural gas; The triethylene glycol regeneration waste gas recovery device is connected to the dehydration absorption tower. The triethylene glycol regeneration waste gas recovery device is used to receive the triethylene glycol rich liquid and perform dehydration regeneration treatment on the triethylene glycol rich liquid to generate triethylene glycol lean liquid and the first raw gas; The dry gas-lean liquid heat exchanger is respectively connected to the dehydration absorption tower and the dry gas coalescence and liquid separation unit. It is used to receive the dehydrated natural gas and perform heat exchange treatment on the dehydrated natural gas. The heat-exchanged natural gas enters the dry gas coalescence and liquid separation unit, and the dry gas coalescence and liquid separation unit is used to perform coalescence and liquid separation treatment on the heat-exchanged natural gas; The dry gas-lean liquid heat exchanger is also used to receive triethylene glycol lean liquid, and the triethylene glycol lean liquid enters the dehydration absorption tower; The lean liquid circulation pump group is respectively connected to the triethylene glycol regeneration waste gas recovery device and the dry gas-lean liquid heat exchanger.

10. A method for recovering the regenerated waste gas of triethylene glycol, characterized in that, The method is implemented by the triethylene glycol regeneration waste gas recovery system according to any one of claims 1-8, and includes: The rich liquid regenerator receives the triethylene glycol rich liquid and performs heating treatment on the triethylene glycol rich liquid; The pretreatment device receives the heated triethylene glycol rich liquid and performs flash evaporation and filtration treatment on the heated triethylene glycol rich liquid to make the heated triethylene glycol rich liquid reach the preset rectification conditions. After the triethylene glycol rich liquid reaching the rectification conditions flows through the rich-lean liquid heat exchanger, it enters the rich liquid regenerator for rectification treatment to obtain triethylene glycol lean liquid and regeneration waste gas; The waste gas treatment device receives the regeneration waste gas and performs condensation and pressurization treatment on the regeneration waste gas to generate water and the first fuel gas, and sprays out the first fuel gas.

11. A method for dehydrating natural gas, characterized in that, The method is implemented by the natural gas dehydration treatment system according to claim 8, and includes: The raw gas filtration unit receives natural gas and filters the natural gas raw material; The dehydration absorption tower receives the filtered natural gas, so that the triethylene glycol lean liquid inside dehydrates the filtered natural gas to obtain triethylene glycol rich liquid and dehydrated natural gas; The triethylene glycol regeneration waste gas recovery device receives the triethylene glycol rich liquid and performs dehydration regeneration treatment on the triethylene glycol rich liquid to generate triethylene glycol lean liquid and the first raw gas; The dry gas-lean liquid heat exchanger receives the dehydrated natural gas and performs heat exchange treatment on the dehydrated natural gas. The heat-exchanged natural gas enters the dry gas coalescence and liquid separation unit; The dry gas coalescence and liquid separation unit performs coalescence and liquid separation treatment on the heat-exchanged natural gas; The dry gas-lean liquid heat exchanger receives triethylene glycol lean liquid, and the triethylene glycol lean liquid enters the dehydration absorption tower.

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