BOG flash evaporation throttling helium extraction denitrification device and natural gas production system
By using a three-stage separator and a multi-channel condenser design in the BOG flash evaporation and throttling helium nitrogen removal device, the existing BOG recovery methods have solved the problems of many equipment, high failure rate and inability to separate nitrogen, and efficient helium recovery and nitrogen separation effects have been achieved.
Patent Information
- Application Number
- CN202420678585.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-03
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2034-04-03
AI Technical Summary
The existing BOG methods for recycling helium have problems such as many dynamic equipment, high failure rate, high power consumption, difficulty in keeping cold, and large liquid nitrogen consumption, and cannot effectively separate and increase the calorific value of methane.
The BOG flash throttling helium nitrogen removal device including a compressor, condenser, separator, dehydrogenation reactor and PSA device is adopted. Through the multi-channel design in the three-stage separator and condenser, the separation of nitrogen and high purity recovery of helium are achieved.
The separation of nitrogen and high purity recovery of helium (the purity of helium can reach 99.999%, and the recovery rate can reach more than 97%) is achieved, which reduces the demand and consumption of refrigerant and reduces the use of traditional helium-extracting membrane equipment.
Smart Images
Figure CN222613278U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of industrial gas separation, in particular to a BOG flash throttling helium extraction and nitrogen removal device and a natural gas production system. Background Art
[0002] At present, LNG (liquefied natural gas), as a form of storage and transportation of natural gas, a clean energy, is widely used in coastal cities for gas security and peak load regulation. LNG receiving stations are widely distributed in coastal cities. The large amount of BOG (flash steam) generated during their operation poses a threat to the safety of the receiving stations. BOG is the gas formed after LNG is heated and vaporized. Due to the limitations of insulation materials, heat inevitably penetrates from the outside, causing LNG to evaporate and produce BOG gas. The total amount of BOG in large LNG stations is large, and direct emissions cause energy waste and environmental pollution.
[0003] At present, many regions have a high proportion of helium imports, and recovering helium from BOG can reduce external dependence and has very good application prospects. The traditional methods of recovering helium from BOG mainly include the following two routes: (1) using multi-stage membrane separation plus pressure swing adsorption to recover helium. The main disadvantages of this method are many moving equipment, high potential failure rate, and high power consumption; (2) using deep cold separation at liquid nitrogen temperature plus deep cold adsorption. The main disadvantages of this method are difficulty in keeping cold, high liquid nitrogen consumption, complex deep cold adsorption process, and complex regeneration. In addition, neither route will separate enriched nitrogen, and the calorific value of recovered methane is low.
[0004] In view of this, the present utility model is proposed. Utility Model Content
[0005] The utility model aims to provide a BOG flash throttling helium extraction and denitrification device and a natural gas production system, which can separate nitrogen to obtain helium and methane products with higher purity.
[0006] The embodiment of the utility model is achieved as follows:
[0007] In a first aspect, the utility model provides a BOG flash throttling helium extraction and denitrification device, comprising a compressor, a condenser, a separator, a dehydrogenation reactor and a PSA device, wherein the separator comprises a primary separator; at least a first flow channel and a second flow channel which do not flow to each other are arranged in the condenser;
[0008] The compressor is provided with a BOG gas inlet, the compressor outlet is connected to the inlet of the first flow channel of the condenser, the outlet of the first flow channel is connected to the inlet of the primary separator, the top gas phase outlet of the primary separator is connected to the inlet of the second flow channel of the condenser, the outlet of the second flow channel is connected to the raw material inlet of the dehydrogenation reactor device, and the outlet of the dehydrogenation reactor is connected to the raw material inlet of the PSA device;
[0009] In an optional embodiment, the separator further includes a secondary separator and a tertiary separator, and a third flow channel and a fourth flow channel are further provided in the condenser;
[0010] The bottom liquid phase outlet of the first-stage separator is connected to the feed port of the second-stage separator, the bottom liquid phase outlet of the second-stage separator is connected to the feed port of the third-stage separator, the top gas phase outlet of the third-stage separator is connected to the inlet of the third flow channel of the condenser, so as to output enriched nitrogen at the outlet of the third flow channel; the bottom liquid phase outlet of the third-stage separator is connected to the inlet of the fourth flow channel of the condenser, so as to output methane-rich gas at the outlet of the fourth flow channel.
[0011] In an optional embodiment, a fifth flow channel is further provided in the condenser, the top gas phase outlet of the secondary separator is connected to the inlet of the fifth flow channel, and the outlet of the fifth flow channel is connected to the inlet of the compressor.
[0012] In an optional embodiment, a sixth flow channel for supplementing refrigerant is further provided in the condenser.
[0013] In an optional embodiment, a cooler is further provided between the compressor and the condenser, the inlet of the cooler is communicated with the outlet of the compressor, and the outlet of the cooler is communicated with the inlet of the first flow channel of the condenser.
[0014] In an optional embodiment, the PSA device has a qualified product outlet and a desorption gas outlet, and the desorption gas outlet is connected to the inlet of the compressor.
[0015] In an optional embodiment, a first cold source feed pipeline is connected to the connecting pipeline between the bottom liquid phase outlet of the three-stage separator and the fourth flow channel.
[0016] In an optional embodiment, a second cold source feed pipeline is provided on the connecting pipeline between the top gas phase outlet of the three-stage separator and the third flow channel.
[0017] In a second aspect, the utility model provides a natural gas production system, comprising a BOG flash throttling helium extraction and nitrogen removal device according to any one of the aforementioned embodiments.
[0018] The beneficial effects of the embodiment of the utility model are as follows: a three-stage separator is used and at least four flow channels that do not flow to each other are set in the condenser, the BOG gas after being pressurized by the compressor enters the first flow channel of the condenser, and then enters the first-stage separator to separate the gas-liquid two phases, the gas phase (non-condensable gas is mainly helium) passes through the second flow channel of the condenser and enters the dehydrogenation reactor to remove hydrogen and then enters the PSA device for helium extraction; the liquid phase of the first-stage separator is separated by the second-stage separator, and the liquid phase of the second-stage separator is separated by the third-stage separator, the gas phase separated by the third-stage separator enters the third flow channel of the condenser for treatment and product collection, and the liquid phase separated by the third-stage separator enters the fourth flow channel of the condenser for treatment and product collection. The device provided by the utility model adopts the method of condensate throttling self-cooling to maximize the role of the cold source, reduce the demand and consumption of the amount of cold, and reduce the use of helium extraction membrane equipment, helium extraction membrane pressurization, cooling, separation and other supporting equipment in the conventional process. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.
[0020] Figure 1 This is a schematic diagram of a BOG flash throttling helium extraction and nitrogen removal device provided in an embodiment of the utility model.
[0021] Icons: 100-BOG flash throttling helium extraction and denitrification device; 110-compressor; 120-cooler; 130-condenser; 131-first flow channel; 132-second flow channel; 133-third flow channel; 134-fourth flow channel; 135-fifth flow channel; 136-sixth flow channel; 140-separator; 141-primary separator; 142-secondary separator; 143-tertiary separator; 150-PSA device; 151-qualified product discharge port; 152-analysis gas discharge port; 160-dehydrogenation reactor; 001-first cold source feed pipeline; 002-second cold source feed pipeline. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.
[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0025] In the description of the present utility model, it should be noted that the terms "upper", "lower", "inner", "outer", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply 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 a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0026] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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.
[0028] The embodiment of the utility model provides a BOG flash throttling helium extraction and nitrogen removal device 100, which includes a compressor 110, a cooler 120, a condenser 130, a separator 140, a dehydrogenation reactor 160 and a PSA device 150.
[0029] The compressor 110 is provided with a BOG gas inlet. The specific model of the compressor 110 is not limited and is used to pressurize the BOG gas. The BOG flash throttling helium extraction and denitrification device 100 provided in the embodiment of the utility model only requires one compressor.
[0030] The cooler 120 is a supporting device of the compressor 110. The gas pressurized by the compressor 110 can be initially cooled by the cooler 120 and then enter the condenser 130. The cooler 120 uses a coolant such as water or air as a refrigerant medium to cool the heat medium, thereby playing a role in initially cooling the BOG gas.
[0031] The condenser 130 is used to convert the BOG gas into liquid, and then the BOG gas enters the separator 140 for gas-liquid separation.
[0032] The embodiment of the utility model improves the structure of the condenser 130 and the separator 140. The separator 140 adopts a three-stage separation method, including a first-stage separator 141, a second-stage separator 142 and a third-stage separator 143 connected in sequence. The bottom liquid phase outlet of the first-stage separator 141 is connected to the feed port of the second-stage separator 142, and the bottom liquid phase outlet of the second-stage separator 142 is connected to the feed port of the third-stage separator 143. The second-stage separator 142 is used to re-separate the liquid phase material output from the bottom of the first-stage separator 141, and the third-stage separator 143 is used to re-separate the liquid phase material output from the bottom of the second-stage separator 142. The three-stage separation throttling is adopted to realize helium recovery and nitrogen separation at the same time. The first stage recovers a large amount of helium, the second stage flash separation recovers dissolved helium, and the third stage flash separation removes nitrogen. The device provided by the utility model uses the condensate throttling after the BOG gas is condensed as a cold source, which can provide a cold source for the BOG condensation process and achieve the purpose of denitrification.
[0033] Furthermore, at least a first flow channel 131, a second flow channel 132, a third flow channel 133, and a fourth flow channel 134 that do not flow into each other are provided in the condenser 130. The working principles of the four flow channels are described below:
[0034] First flow channel 131: A cooler 120 is further provided between the compressor 110 and the condenser 130, the inlet of the cooler 120 is communicated with the outlet of the compressor 110, and the outlet of the cooler 120 is communicated with the inlet of the first flow channel 131 of the condenser 130. The material outputted from the compressor 110 is communicated with the inlet of the first flow channel 131 of the condenser 130 after passing through the cooler 120, and the outlet of the first flow channel 131 is communicated with the inlet of the primary separator 141, and enters the primary separator 141 for gas-liquid separation.
[0035] Second flow channel 132: the non-condensable gas output from the top gas phase outlet of the first-level separator 141 is mainly helium, which is connected to the inlet of the second flow channel 132 of the condenser 130, and the outlet of the second flow channel 132 is connected to the inlet of the dehydrogenation reactor 160, and the outlet of the dehydrogenation reactor 160 is connected to the raw material inlet of the PSA device 150. After being processed by the condenser 130, it enters the dehydrogenation reactor 160 for dehydrogenation, and after dehydrogenation, it enters the PSA device 150 for helium extraction. After being processed by the dehydrogenation reactor 160 and the PSA device 150, the purity of the helium can reach more than 99.999%, and the helium recovery rate can reach more than 97%.
[0036] The third flow channel 133: The top gas phase outlet of the third-stage separator 143 is connected to the inlet of the third flow channel 133 of the condenser 130, so as to output the enriched nitrogen at the outlet of the third flow channel 133. Most of the gas phase material output from the top of the third flow channel 133 is nitrogen, which is discharged after being reheated by the condenser 130.
[0037] Fourth flow channel 134: the liquid phase material output from the bottom liquid phase outlet of the third-stage separator 143 is mainly LNG product, which enters the fourth flow channel 134 of the condenser 130 to output methane-rich gas at the outlet of the fourth flow channel 134 for use as fuel.
[0038] In some embodiments, a fifth flow channel 135 is further provided in the condenser 130, and the top gas phase outlet of the secondary separator 142 is connected to the inlet of the fifth flow channel 135, and the outlet of the fifth flow channel 135 is connected to the inlet of the compressor 110. The dissolved helium is recovered from the secondary separation gas phase and returned to the compressor 110 after being processed by the fifth flow channel 135, thereby improving the helium yield.
[0039] In some embodiments, a sixth flow channel 136 for supplementing refrigerant is further provided in the condenser 130. When the cooling capacity is sufficient, the cold source may not be supplemented. By providing a separate flow channel in the condenser 130 to supplement the cold source, the condensation process can be stably guaranteed.
[0040] Furthermore, a first cold source replenishment pipeline 001 is connected to the connecting pipeline between the bottom liquid phase outlet of the three-stage separator 143 and the fourth flow channel 134. A second cold source replenishment pipeline 002 is provided on the connecting pipeline between the top gas phase outlet of the three-stage separator 143 and the third flow channel 133. The first cold source replenishment pipeline 001 and the second cold source replenishment pipeline 002 are used to supplement the cold source for the device to ensure the condensation process. The cold source replenishment can be set separately or in combination. When the cold capacity is sufficient, the cold source may not be supplemented. The first cold source replenishment pipeline 001 is used to supplement the LNG cold source, and the second cold source replenishment pipeline 002 is used to supplement liquid nitrogen as a cold source. When the cold capacity is insufficient during the initial start-up or the BOG condensation process, the cold source is supplemented by adding liquid nitrogen / LNG through the reserved port of the three-stage separator.
[0041] Specifically, the six unconnected flow channels in the condenser 130 are arranged, the BOG gas entering the first flow channel 131 is a heat medium, and the materials entering the other five flow channels are all refrigerants, which are used to condense the BOG gas. The three separators are conventional gas-liquid separators, and the specific operating parameters of the primary separator 141, the secondary separator 142 and the tertiary separator 143 are different. The operating parameters of the primary separator 141 are 1.5-3 MPa; the operating parameters of the secondary separator 142 are 0.5-1 MPa; and the operating parameters of the tertiary separator 143 are 0.01-0.5. Furthermore, the PSA device 150 has a qualified product outlet 151 and a desorption gas outlet 152. The qualified product outlet 151 outputs high-concentration helium with a purity of up to 99.999%; the desorption gas outlet 152 is used to output low-concentration helium. The desorption gas outlet 152 is connected to the inlet of the compressor 110 to reflux the desorption gas to the inlet of the first-stage BOG compressor for recycling, thereby ensuring the recovery rate of helium.
[0042] Specifically, the PSA device 150 is a conventional pressure swing adsorption helium extraction device, which removes other impurity gases except helium by pressure swing adsorption. The principle of pressure swing adsorption separation is to achieve adsorption and desorption processes by controlling the rise and fall of pressure. When the pressure is increased, the adsorbent first adsorbs the strongly adsorbed components in the mixed gas under high pressure. When the adsorption is saturated, the adsorption tower enters the regeneration process, and the adsorbate is desorbed from the adsorption bed by reducing the pressure, and the unadsorbed components are discharged through the adsorption layer. Due to the different adsorption and desorption characteristics of different gases, separation can be achieved during the periodic change of pressure.
[0043] The embodiment of the utility model further provides a natural gas production system, including a BOG flash throttling helium extraction and nitrogen removal device 100, and may also include other equipment for LNG liquefied natural gas production to form a complete natural gas production system. Specific embodiments
[0045] This embodiment utilizes Figure 1 The BOG flash throttling helium extraction and nitrogen removal device 100 separates the BOG gas, and the specific steps are as follows:
[0046] Raw BOG gas composition: 77% methane, 22% nitrogen, 1% helium.
[0047] The first-stage separator 141 separates the gas and liquid components at the outlet of the first flow channel 131, and the operating parameter is 2.0MpaG; the second-stage separator 142 separates the gas and liquid components at the liquid phase throttling outlet of the first-stage separator 141, and the operating parameter is 0.8MpaG; the third-stage separator 143 separates the gas and liquid components at the liquid phase throttling outlet of the second-stage separator 142, and the operating parameter is 0.2MpaG.
[0048] The BOG gas is pressurized to 2.0 MPaG by the compressor 110, cooled to 40°C by the cooler 120, and then enters the first flow channel 131 of the condenser 130 for condensation and then enters the primary separator 141 for gas-liquid separation. The gaseous material output from the top of the primary separator 141 enters the second flow channel 132 for reheating to 40°C and enters the dehydrogenation reactor 160, and then output from the dehydrogenation reactor 160 to enter the PSA device 150. After treatment, a helium product with a purity of more than 99.999% is obtained.
[0049] The liquid phase material output from the bottom of the primary separator 141 enters the secondary separator 142 for separation, and the gas phase material output from the top of the secondary separator 142 is processed by the fifth flow channel 135 and then returns to the compressor 110. The liquid phase material output from the bottom of the secondary separator 142 enters the tertiary separator 143 for separation. A throttle valve is provided on the connecting pipeline between the primary separator 141 and the secondary separator 142, and a throttle valve is also provided on the connecting pipeline between the secondary separator 142 and the tertiary separator 143.
[0050] The gaseous material output from the top of the three-stage separator 143 enters the third flow channel 133 to output enriched nitrogen (purity of 82%) at the outlet of the third flow channel 133. The liquid material output from the bottom liquid outlet of the three-stage separator 143 is processed by the fourth flow channel 134 to output methane-rich gas (purity of 87%) at the outlet of the fourth flow channel 134 for fuel.
[0051] In summary, the utility model provides a BOG flash throttling helium denitrification device and a natural gas production system. After the BOG gas is pressurized, it enters the BOG condenser, and then separates the gas and liquid phases through the BOG condensation separator. The liquid phase is throttled by the throttle and serves as a cold source to provide cold for the BOG condensation process. After the liquid phase is throttled for the second time, nitrogen can be drawn out for enrichment to achieve the purpose of denitrification. The separated gas phase is treated by a dehydrogenation reactor and a PSA device, and the helium purity can reach 99.999%. The helium recovery rate of the process provided by the embodiment of the utility model can reach more than 99%.
[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A BOG flash throttling helium extraction and nitrogen removal device, characterized in that: The invention comprises a compressor, a condenser, a separator, a dehydrogenation reactor and a PSA device, wherein the separator comprises a primary separator; the condenser is provided with at least a first flow channel and a second flow channel which do not flow into each other; The compressor is provided with a BOG gas inlet, the outlet of the compressor is connected to the inlet of the first flow channel of the condenser, the outlet of the first flow channel is connected to the inlet of the primary separator, the top gas phase outlet of the primary separator is connected to the inlet of the second flow channel of the condenser, the outlet of the second flow channel is connected to the raw material inlet of the dehydrogenation reactor device, and the outlet of the dehydrogenation reactor is connected to the raw material inlet of the PSA device.
2. The BOG flash throttling helium extraction and nitrogen removal device according to claim 1, characterized in that: The separator further comprises a secondary separator and a tertiary separator, and the condenser is further provided with a third flow channel and a fourth flow channel; The bottom liquid phase outlet of the first-stage separator is connected to the feed port of the second-stage separator, the bottom liquid phase outlet of the second-stage separator is connected to the feed port of the third-stage separator, the top gas phase outlet of the third-stage separator is connected to the inlet of the third flow channel of the condenser, so as to output enriched nitrogen at the outlet of the third flow channel; the bottom liquid phase outlet of the third-stage separator is connected to the inlet of the fourth flow channel of the condenser, so as to output methane-rich gas at the outlet of the fourth flow channel.
3. The BOG flash throttling helium extraction and nitrogen removal device according to claim 2, characterized in that: A fifth flow channel is also provided in the condenser, the top gas phase outlet of the secondary separator is communicated with the inlet of the fifth flow channel, and the outlet of the fifth flow channel is communicated with the inlet of the compressor.
4. The BOG flash throttling helium extraction and nitrogen removal device according to claim 3 is characterized in that: The condenser is also provided with a sixth flow channel for supplementing refrigerant.
5. The BOG flash throttling helium extraction and nitrogen removal device according to claim 3 is characterized in that: A cooler is further provided between the compressor and the condenser. The inlet of the cooler is communicated with the outlet of the compressor, and the outlet of the cooler is communicated with the inlet of the first flow channel of the condenser.
6. The BOG flash throttling helium extraction and nitrogen removal device according to claim 3, characterized in that: The PSA device is provided with a qualified product outlet and a desorption gas outlet, and the desorption gas outlet is communicated with the inlet of the compressor.
7. The BOG flash throttling helium extraction and nitrogen removal device according to claim 2, characterized in that: A first cold source feed pipeline is connected to the connecting pipeline between the bottom liquid phase outlet of the three-stage separator and the fourth flow channel.
8. The BOG flash throttling helium extraction and nitrogen removal device according to claim 2 or 7, characterized in that: A second cold source feeding pipeline is arranged on the connecting pipeline between the top gas phase outlet of the three-stage separator and the third flow channel.
9. A natural gas production system, characterized in that: It comprises the BOG flash throttling helium extraction and nitrogen removal device as described in any one of claims 1 to 8.