Vehicle-mounted movable SMR-PHE natural gas liquefaction device

Abstract

The invention discloses a vehicle-mounted movable SMR-PHE natural gas liquefaction device which is used for obtaining liquefied petroleum gas (LPG) and liquefied natural gas (LNG) products by using refrigerant circulating cooling feed gas, and the refrigerant circulating cooling feed gas is subjected to a refrigerant pressurization stage, a refrigerant temperature and pressure reduction stage and a feed gas cooling stage. The refrigerant passes through the first heat exchanger, the second heat exchanger and the second throttle valve during cooling and depressurization, and the feed gas passes through the third heat exchanger and the fourth heat exchanger during cooling; the first heat exchanger, the second heat exchanger, the third heat exchanger and the fourth heat exchanger are two-flow plate type heat exchangers. The vehicle-mounted horizontal cold box adopts the two-flow plate type heat exchanger, the horizontal cold box can be miniaturized, the mixed refrigerant liquefying process flow based on the vehicle-mounted horizontal cold box is optimized, the single-stage mixed refrigerant liquefying circulation based on the horizontal cold box is constructed, the vehicle-mounted requirement can be met, and the purpose that in the vehicle-mounted limited space, the single-stage mixed refrigerant liquefying circulation can be achieved is achieved. And the handling capacity of the cold box is maximized.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-mounted natural gas liquefaction, and in particular to a vehicle-mounted movable SMR-PHE natural gas liquefaction device. Background Art

[0002] With the continuous development of my country's economy, the demand for energy is also growing. At present, the consumption of natural gas as a clean energy in the domestic primary energy consumption accounts for a low proportion, only about 8.1%, which is lower than the global average consumption of natural gas of 24%. An important factor restricting the development and utilization of associated gas in marginal gas fields and oil fields is the transportation of natural gas. Since the gas source is very scattered and far away from the gas supply network, the pipeline transportation method has not been effectively developed and utilized due to economic irrationality. In reality, a set of natural gas liquefaction vehicle-mounted devices that can be used for the recovery of liquefied gas from the venting of marginal scattered gas fields and shale gas pilot wells is needed.

[0003] At present, small skid-mounted natural gas liquefaction devices are mostly used at home and abroad to recover marginal gas fields and vent shale gas. The small skid-mounted natural gas / coalbed methane liquefaction device developed domestically adopts a mixed refrigerant refrigeration cycle plus an R22 pre-cooling cycle, but the device requires on-site pouring of the foundation and then fixing each skid on it, occupying a large area. The on-site conditions of marginal gas fields and shale gas test wells are harsh, and it is difficult to install equipment to recover these gases.

[0004] The on-board natural gas liquefaction device can be used to recover and liquefy the air discharged from marginal scattered gas fields and shale gas test wells without laying pipelines. However, the on-board natural gas liquefaction device has the problem that the natural gas liquefaction process suitable for the on-board horizontal cold box is not easy to construct; the on-board horizontal cold box is limited in size and difficult to develop. At present, conventional small skid-mounted natural gas liquefaction devices use vertical plate-fin heat exchanger cold boxes. Due to the high height of the vertical cold box, it cannot be used in the on-board liquefaction system. Moreover, the mixed refrigerant natural gas liquefaction cycle based on the on-board horizontal cold box is different from the conventional mixed refrigerant liquefaction cycle, and has certain requirements for the boiling pressure, condensing pressure, pre-throttling temperature, compressor inlet superheat, mixed refrigerant dryness, and mixed refrigerant flow distribution coefficient of the mixed refrigerant.

[0005] The patent document with the document number CN115789509A discloses an intelligent vehicle-mounted movable natural gas liquefaction device, which relates to the field of natural gas liquefaction technology, including a raw gas pretreatment unit, a deacidification unit, a dehydration and demercuration unit, a heavy hydrocarbon removal unit, a liquefaction unit, a refrigerant compression unit, a refrigerant storage and recycling unit, an LNG storage unit, an LNG loading unit, an air pressure nitrogen production unit, and a sewage collection unit; the natural gas liquefaction device of the present invention adopts a vehicle-mounted platform instead of a cast-in-place foundation to achieve the fixation of the skid block, and the skid block does not require additional lifting when it is transferred, and the skid block occupies a small area, has low requirements on geological conditions, and can adapt to a variety of terrain conditions; and the system uses the tractor head engine used by each vehicle-mounted platform to form a power system, which provides the power required for the entire system and reduces the system's dependence on the external environment. However, the application does not disclose the process flow of the refrigerant pressurization stage, the refrigerant cooling and pressure reduction stage, and the raw gas cooling stage. Summary of the invention

[0006] The object of the present invention is to provide a vehicle-mounted movable SMR-PHE natural gas liquefaction device, which is convenient for recovering and liquefying the vented raw gas from marginal scattered gas fields and shale gas test wells.

[0007] The object of the present invention can be achieved by the following technical scheme: a vehicle-mounted mobile SMR-PHE natural gas liquefaction device, used for obtaining liquefied petroleum gas LPG and liquefied natural gas LNG products by using a refrigerant circulation to cool raw gas, the refrigerant circulation cooling raw gas passing through a refrigerant pressurization stage, a refrigerant temperature and pressure reduction stage and a raw gas cooling stage, the refrigerant temperature and pressure reduction passing through a first heat exchanger, a second heat exchanger and a second throttle valve, the raw gas cooling passing through a third heat exchanger and a fourth heat exchanger;

[0008] The first heat exchanger and the second heat exchanger are used for heat exchange between the refrigerant itself;

[0009] The third heat exchanger is used to obtain liquefied natural gas LNG after heat exchange between the raw gas and the refrigerant;

[0010] The fourth heat exchanger is used to obtain liquefied petroleum gas (LPG) after heat exchange between the raw gas and the refrigerant;

[0011] The second heat exchanger and the third heat exchanger are arranged in parallel, and the refrigerant source used for cooling by the second heat exchanger and the third heat exchanger is the same refrigerant;

[0012] The first heat exchanger and the fourth heat exchanger are arranged in parallel, and the refrigerant source used for cooling by the first heat exchanger and the fourth heat exchanger is the same refrigerant;

[0013] Among them, the first heat exchanger, the second heat exchanger, the third heat exchanger and the fourth heat exchanger are plate heat exchangers suitable for vehicle-mounted horizontal cold boxes.

[0014] Further: the process of obtaining LPG after heat exchange between the raw gas and the refrigerant by the fourth heat exchanger is:

[0015] The raw gas NG and the refrigerant J enter the fourth heat exchanger for heat exchange to obtain the raw gas a and the refrigerant L;

[0016] The raw gas a enters the heavy hydrocarbon separator to obtain liquid phase raw gas LPG and gas phase raw gas b.

[0017] Further: the process of obtaining LNG after heat exchange between the raw gas and the refrigerant by the third heat exchanger is:

[0018] The gaseous raw gas b and the refrigerant E enter the third heat exchanger for heat exchange to obtain high-pressure liquefied natural gas c and refrigerant G;

[0019] The high-pressure liquefied natural gas c is depressurized by the first throttle valve to obtain low-pressure liquefied raw gas d, and the low-pressure liquefied raw gas d enters the gas-liquid separator to obtain liquefied natural gas as LNG and gasified natural gas as BOG.

[0020] Further: the first heat exchanger and the second heat exchanger are used for the refrigerant self heat exchange process:

[0021] High-pressure refrigerant U and refrigerant I enter the first heat exchanger for heat exchange. High-pressure refrigerant U is cooled to obtain refrigerant A, and refrigerant I is reheated to obtain refrigerant K.

[0022] Refrigerant A and refrigerant D enter the second heat exchanger for heat exchange. Refrigerant A is cooled to obtain refrigerant B, and refrigerant D is reheated to obtain refrigerant F.

[0023] Refrigerant B is depressurized by the second throttle valve to obtain refrigerant C, and refrigerant C is split by the second splitter to obtain refrigerant D and refrigerant E;

[0024] Refrigerant F and refrigerant G enter the second mixer and mix to obtain refrigerant H, and refrigerant H is split by the first splitter to obtain refrigerant J and refrigerant I;

[0025] The refrigerant L and the refrigerant K enter the first mixer and mix to obtain the low-pressure refrigerant M.

[0026] Further: the refrigerant pressurization stage process is:

[0027] The low-pressure refrigerant M is compressed by the first-stage compressor to obtain refrigerant N, and the refrigerant N is passed through the first water cooler to obtain refrigerant O;

[0028] Refrigerant O enters the separator for gas-liquid separation to obtain gas-phase refrigerant P and liquid-phase refrigerant Q, wherein gas-phase refrigerant P is compressed by the second-stage compressor to obtain refrigerant R, and liquid-phase refrigerant Q is pressurized by the liquid pump to obtain refrigerant S, and refrigerant R and refrigerant S are mixed by the third mixer to obtain refrigerant T;

[0029] The refrigerant T is passed through the second water cooler to obtain high-pressure refrigerant U.

[0030] Further: the components of the refrigerant are: CH4 accounts for 29.12 mol%, C2H4 accounts for 27.53 mol%, C3H8 accounts for 8.42 mol%, i-C5H 12 It accounts for 21.87 mol%, and N2 accounts for 13.06 mol%.

[0031] Beneficial effects of the present invention:

[0032] 1. The present invention adopts a vehicle-mounted horizontal cold box, which adopts a two-flow plate heat exchanger. The horizontal cold box can be designed to be miniaturized. On the premise of meeting the liquefaction process parameters, the size of the cold box can be minimized, which can meet the strict requirements of the vehicle and maximize the cold box processing capacity within the limited space on the vehicle.

[0033] 2. The present invention optimizes the mixed refrigerant liquefaction process based on a vehicle-mounted horizontal cold box, constructs a single-stage mixed refrigerant liquefaction cycle based on a horizontal cold box, and optimizes the design of the mixed refrigerant boiling pressure, condensing pressure, pre-throttling temperature, compressor inlet superheat, mixed refrigerant dryness, mixed refrigerant flow distribution coefficient, etc. The process flow is suitable for the new mixed refrigerant liquefaction of a horizontal cold box.

[0034] 3. The present invention uses a two-stream plate heat exchanger to build a liquefaction process. The process has the advantages of less equipment, simple process, and low investment. Multiple cold and hot fluids that exchange heat in the same vehicle-mounted heat exchanger are separately exchanged in different two-stream plate heat exchangers. The refrigerant C is divided into two paths as a coolant with lower temperature and pressure. One path is used to cool the raw gas through the fourth heat exchanger and the third heat exchanger, and the other path is used to cool the refrigerant through the second heat exchanger and the first heat exchanger, thereby realizing coolant regeneration, thereby realizing the dual effects of the coolant on cooling itself and cooling the raw gas. The two-stream plate heat exchanger is suitable for the internal structure of the vehicle-mounted horizontal cold box, saves space layout, and is convenient to meet the vehicle-mounted size requirements. It is beneficial to the piping of the heat exchanger in the horizontal cold box, and is beneficial to the spatial layout of valves and measuring instruments, thereby maximizing the cold box processing capacity within the limited space on the vehicle.

[0035] 4. The circulating refrigerant of the present invention has a high thermodynamic efficiency. The circulating refrigerant is rationally mixed with CH4, C2H4, C3H8, i-C5H without changing the components.12 The ratio of N2 and the combined cycle performance of two liquefaction cycles are suitable for the new mixed refrigerant liquefaction process of horizontal cold boxes and have good adaptability to natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural schematic diagram of a vehicle-mounted mobile SMR-PHE natural gas liquefaction device of the present invention;

[0037] Figure 2 is a heat exchange curve diagram of the first heat exchanger of the present invention;

[0038] Figure 3 is a heat exchange curve diagram of the second heat exchanger of the present invention;

[0039] Figure 4 is a heat exchange curve diagram of the third heat exchanger of the present invention;

[0040] Figure 5 This is a heat exchange curve diagram of the fourth heat exchanger of the present invention.

[0041] 10. First heat exchanger; 20. Second heat exchanger; 30. Third heat exchanger; 40. Fourth heat exchanger; 50. Heavy hydrocarbon separator; 60. First throttle valve; 70. Gas-liquid separator; 80. Second throttle valve; 90. Second diverter; 100. Second mixer; 110. First mixer; 120. First diverter; 130. First stage compressor; 140. First water cooler; 150. Separator; 160. Second stage compressor; 170. Liquid pump; 180. Third mixer; 190. Second water cooler. DETAILED DESCRIPTION

[0042] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0043] like Figure 1-5 As shown, the present invention discloses a vehicle-mounted mobile SMR-PHE natural gas liquefaction device, which is used to obtain liquefied petroleum gas LPG and liquefied natural gas LNG products by cooling raw gas through refrigerant circulation.

[0044] When the refrigerant circulates to cool the raw gas, it passes through a refrigerant pressurization stage, a refrigerant temperature and pressure reduction stage, and a raw gas cooling stage. When the refrigerant is cooled and pressure reduced, it passes through a first heat exchanger 10, a second heat exchanger 20, and a second throttle valve 80. When the raw gas is cooled, it passes through a third heat exchanger 30 and a fourth heat exchanger 40.

[0045] The first heat exchanger 10 and the second heat exchanger 20 are used for heat exchange of the refrigerant itself;

[0046] The third heat exchanger 30 is used to obtain liquefied natural gas LNG after heat exchange between the raw gas and the refrigerant;

[0047] The fourth heat exchanger 40 is used to obtain liquefied petroleum gas LPG after heat exchange between the raw gas and the refrigerant;

[0048] The second heat exchanger 20 and the third heat exchanger 30 are arranged in parallel, and the refrigerant used for cooling by the second heat exchanger 20 and the third heat exchanger 30 is the same refrigerant;

[0049] The first heat exchanger 10 and the fourth heat exchanger 40 are arranged in parallel, and the refrigerant used for cooling by the first heat exchanger 10 and the fourth heat exchanger 40 is from the same refrigerant;

[0050] The first heat exchanger 10, the second heat exchanger 20, the third heat exchanger 30 and the fourth heat exchanger 40 are plate heat exchangers suitable for a vehicle-mounted horizontal cold box.

[0051] The mixed refrigerant liquefaction process is a single mixed refrigerant liquefaction process (Single Mixed Refrigerant Cycle, referred to as SMR), but SMR generally uses a vertical plate-fin heat exchanger cold box, and the plate-fin heat exchanger cold box is a vertical cold box. Since the vertical cold box is high, it cannot be used in a vehicle-mounted liquefaction system, so the traditional SMR is not suitable for a vehicle-mounted liquefaction system. The plate heat exchanger (PHE) is a two-stream heat exchanger, which can better control the relevant cycle parameters such as the boiling pressure, condensing pressure, pre-throttling temperature, compressor inlet superheat, mixed refrigerant dryness, and mixed refrigerant flow distribution coefficient of the mixed refrigerant. It has a small volume and is more flexible in application, which is conducive to the development and design of the mixed refrigerant liquefaction process. Therefore, the plate heat exchanger (PHE) is used to optimize the single-cycle mixed refrigerant liquefaction process (SMR), and the SMR-PHE natural gas liquefaction device obtained by design can be better used for vehicle-mounted mobile use.

[0052] Example:

[0053] like Figure 1 As shown, the present invention is based on the mixed refrigerant liquefaction process of the vehicle-mounted horizontal cold box, and constructs a mixed refrigerant process of the vehicle-mounted horizontal cold box SMR-PHE natural gas liquefaction device, which mainly includes a refrigerant pressurization stage, a refrigerant temperature and pressure reduction stage, and a raw gas cooling stage.

[0054] In the raw gas cooling stage, the raw gas NG (35°C, 5000 kPa) is subjected to adsorption purification treatment, and the raw gas NG (35°C, 5000 kPa) and the refrigerant J (-45.26°C, 190 kPa) enter the fourth heat exchanger 40 for heat exchange to obtain raw gas a (-40°C, 4990 kPa) and refrigerant L (28.49°C, 180 kPa); the raw gas a (-40°C, 4990 kPa) then enters the heavy hydrocarbon separator 50, and the heavy hydrocarbon separator 50 separates the raw gas a (-40°C, 4990 kPa) to obtain liquid phase raw gas LPG (-40°C, 4990 kPa) and gas phase raw gas b (-40°C, 4990 kPa), and the gas phase raw gas b ( -40℃, 4990kPa) enters the third heat exchanger 30 for heat exchange with refrigerant E (-167.3℃, 200kPa) to obtain high-pressure liquefied natural gas c (-160℃, 4980kPa) and refrigerant G (-49.33℃, 190kPa); wherein the high-pressure liquefied natural gas c (-160℃, 4980kPa) is reduced in pressure by the first throttle valve 60 to obtain low-pressure liquefied raw gas d (-160.4℃, 150kPa), and the low-pressure liquefied raw gas d (-160.4℃, 150kPa) enters the gas-liquid separator 70 to obtain liquefied natural gas LNG (-160.4℃, 150kPa) and gasified natural gas BOG (-160.4℃, 150kPa).

[0055] Furthermore, gasified natural gas BOG (-160.4°C, 150kPa) can also be used as a coolant to go to the fourth heat exchanger 40 to reheat the raw gas NG. After the BOG (-160.4°C, 150kPa) is reheated, the temperature and pressure are (25°C, 150kPa). The raw gas NG is cooled by BOG (-160.4°C, 150kPa) to obtain raw gas a (-40°C, 4990kPa). This structure can achieve the cooling of the raw gas NG while achieving the BOG reheating, thereby reducing the energy consumption of the system.

[0056] During the refrigerant pressurization stage, the refrigerant used in the entire device is circulated and reheated, and the refrigerant is circulated and reheated from the high-pressure refrigerant U (40°C, 1800kPa) to obtain the low-pressure refrigerant M (36.81°C, 180kPa).

[0057] The process is as follows: high-pressure refrigerant U (40°C, 1800 kPa) and refrigerant I (-45.26°C, 190 kPa) enter the first heat exchanger 10 for heat exchange, high-pressure refrigerant U (40°C, 1800 kPa) is cooled to obtain refrigerant A (-40°C, 1790 kPa), and refrigerant I (-45.26°C, 190 kPa) is reheated to obtain refrigerant K (37.71°C, 180 kPa);

[0058] Refrigerant A (-40°C, 1790 kPa) and refrigerant D enter the second heat exchanger 20 for heat exchange. Refrigerant A (-40°C, 1790 kPa) is cooled to obtain refrigerant B (-160°C, 1780 kPa), and refrigerant D (-167.3°C, 200 kPa) is reheated to obtain refrigerant F (-43.97°C, 190 kPa).

[0059] The refrigerant B (-160°C, 1780 kPa) is depressurized by the second throttle valve 80 to obtain refrigerant C (-167.3°C, 200 kPa), and the refrigerant C (-167.3°C, 200 kPa) is split by the second splitter 90 to obtain refrigerant D (-167.3°C, 200 kPa) and refrigerant E (-167.3°C, 200 kPa);

[0060] Refrigerant F (-43.97°C, 190 kPa) and refrigerant G (-49.33°C, 190 kPa) enter the second mixer 100 and mix to obtain refrigerant H (-45.26°C, 190 kPa);

[0061] Refrigerant H (-45.26° C., 190 kPa) is split by the first splitter 120 to obtain refrigerant J (-45.26° C., 190 kPa) and refrigerant I (-45.26° C., 190 kPa);

[0062] The refrigerant K (37.71° C., 180 kPa) and the refrigerant L (28.49° C., 180 kPa) enter the first mixer 110 and are mixed to obtain a low-pressure refrigerant M (36.81° C., 180 kPa).

[0063] In the refrigerant pressurization stage, low-pressure refrigerant M (36.81°C, 180 kPa) is used to obtain high-pressure refrigerant U (40°C, 1800 kPa).

[0064] The process is as follows: low-pressure refrigerant M (36.81°C, 180 kPa) is compressed by the first-stage compressor 130 to obtain refrigerant N (120.7°C, 800 kPa), and refrigerant N (120.7°C, 800 kPa) is passed through the first water cooler 140 to obtain refrigerant O (40°C, 800 kPa);

[0065] Refrigerant O (40°C, 800 kPa) enters the separator 150 for gas-liquid separation to obtain gas-phase refrigerant P (40°C, 800 kPa) and liquid-phase refrigerant Q (40°C, 800 kPa), wherein the gas-phase refrigerant P (40°C, 800 kPa) is compressed by the second-stage compressor 160 to obtain refrigerant R (88.57°C, 1800 kPa), and the liquid-phase refrigerant Q (40°C, 800 kPa) is pressurized by the liquid pump 170 to obtain refrigerant S (40.73°C, 1800 kPa), and the refrigerant R (88.57°C, 1800 kPa) and the refrigerant S (40.73°C, 1800 kPa) are mixed by the third mixer 180 to obtain refrigerant T (77.11°C, 1800 kPa);

[0066] The refrigerant T (77.11° C., 1800 kPa) passes through the second water cooler 190 to obtain high-pressure refrigerant U (40° C., 1800 kPa).

[0067] like Figure 1 As shown, when the refrigerant circulates to cool the raw gas, it goes through the refrigerant pressurization stage, the refrigerant temperature and pressure reduction stage, and the raw gas cooling stage. The entire process is compact and simple in structure, with fewer unit equipment.

[0068] During the pressurization stage, the low-pressure refrigerant M is pressurized twice by the first-stage compressor 130, the second-stage compressor 160 and the liquid pump 170, and the pressure is increased from 180 kPa to 1800 kPa, thereby realizing refrigerant pressurization. The temperature of the low-pressure refrigerant M increases while the low-pressure refrigerant M is pressurized. The low-pressure refrigerant M is cooled by 40°C twice by the first water cooler 140 and the second water cooler 190, thereby realizing the overall pressurization and cooling of the low-pressure refrigerant M to the high-pressure refrigerant U.

[0069] During the cooling and pressure reduction stage, the high-pressure refrigerant U first enters the first heat exchanger 10 and performs the first heat exchange with the refrigerant J in a low-temperature state. After being cooled by the first heat exchanger 10, the high-pressure refrigerant U obtains the -40°C refrigerant A, and then continues to pass through the second heat exchanger 20 to continue to perform heat exchange with the refrigerant D to obtain the -160°C refrigerant B. The -160°C refrigerant B is reduced in pressure and temperature by the second throttle valve 80 to obtain the -167.3°C refrigerant C, thereby achieving the goal that after the high-pressure refrigerant U is reduced in pressure and temperature by the first heat exchanger 10, the second heat exchanger 20 and the second throttle valve 80, the refrigerant C with lower temperature and pressure (-167.3°C, 200kPa) is obtained.

[0070] In the raw gas cooling stage, the -167.3°C refrigerant C exchanges heat with the raw gas through the third heat exchanger 30 and the fourth heat exchanger 40 respectively to obtain liquefied natural gas LNG and liquefied petroleum gas LPG.

[0071] like Figure 1As shown, the present invention uses a two-stream plate heat exchanger to build a liquefaction process. The process has the advantages of less equipment, simple process, and low investment. Multiple cold and hot fluids that exchange heat in the same vehicle-mounted heat exchanger are separately exchanged in different two-stream plate heat exchangers. The refrigerant C is divided into two paths as a coolant with lower temperature and pressure. One path is used to cool the raw gas through the fourth heat exchanger 40 and the third heat exchanger 30, and the other path is used to cool the refrigerant through the second heat exchanger 20 and the first heat exchanger 10, so as to realize the regeneration of the coolant, thereby realizing the self-regeneration of the coolant. It has the dual functions of cooling the gas itself and cooling the raw gas. The two-flow plate heat exchanger for building the liquefaction process is suitable for the internal structure of the vehicle-mounted horizontal cold box, which saves space for layout, is convenient to meet the size requirements of the vehicle, is beneficial to the piping of the heat exchanger in the horizontal cold box, and is beneficial to the spatial layout of valves and measuring instruments, thereby realizing the maximization of the cold box processing capacity within the limited space on the vehicle. After experimental testing, the vehicle-mounted horizontal cold box for building the liquefaction process using the two-flow plate heat exchanger of the present invention can process 50,000 cubic meters of raw gas per day, and has better processing capacity.

[0072] The present invention adopts a two-stream plate heat exchanger, which has better heat exchange performance, such as Figure 2-5 As shown, the two-stream plate heat exchanger can achieve the minimum temperature difference between the cold and hot flows, and thus obtain extremely high refrigeration efficiency. The components of the refrigerant of the present invention can be: CH4 accounts for 29.12 mol%, C2H4 accounts for 27.53 mol%, C3H8 accounts for 8.42 mol%, i-C5H 12 Oxygen accounts for 21.87 mol%, and N2 accounts for 13.06 mol%. When the natural gas composition is determined, the mixed cycle refrigerant has a higher thermodynamic efficiency; when the natural gas conditions (such as pressure, composition and flow) change within a certain range, the circulating refrigerant has good adaptability to natural gas without changing the composition, and is suitable for the new mixed refrigerant liquefaction process flow of horizontal cold boxes.

[0073] At the same time, due to the harsh conditions at marginal gas fields and shale gas test wellheads, most of them do not have high-power power supply facilities. The best source of power required for vehicle-mounted natural gas liquefaction devices is vehicle engines. Reasonable use of the energy that vehicle engines rely on can continuously provide energy for vehicle engines and reduce vehicle engines' dependence on long-distance fossil energy replenishment. Heavy-duty truck engines that use LNG as fuel can achieve on-site replenishment of engine energy consumption.

[0074] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0075] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0076] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0077] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A vehicle-mounted mobile SMR-PHE natural gas liquefaction device, used to obtain liquefied petroleum gas (LPG) and liquefied natural gas (LNG) products by cooling raw gas using a refrigerant cycle, characterized in that: When the refrigerant circulates to cool the raw gas, it passes through a refrigerant pressurization stage, a refrigerant temperature and pressure reduction stage, and a raw gas cooling stage. When the refrigerant is cooled and pressure reduced, it passes through a first heat exchanger (10), a second heat exchanger (20), and a second throttle valve (80). When the raw gas is cooled, it passes through a third heat exchanger (30) and a fourth heat exchanger (40); The first heat exchanger (10) and the second heat exchanger (20) are used for heat exchange of the refrigerant itself; The third heat exchanger (30) is used to obtain liquefied natural gas LNG after heat exchange between the raw gas and the refrigerant; The fourth heat exchanger (40) is used to obtain liquefied petroleum gas (LPG) after heat exchange between the raw gas and the refrigerant; The second heat exchanger (20) and the third heat exchanger (30) are arranged in parallel, and the refrigerant used for cooling by the second heat exchanger (20) and the third heat exchanger (30) is sourced from the same refrigerant; The first heat exchanger (10) and the fourth heat exchanger (40) are arranged in parallel, and the refrigerant used for cooling by the first heat exchanger (10) and the fourth heat exchanger (40) is sourced from the same refrigerant; Wherein, the first heat exchanger (10), the second heat exchanger (20), the third heat exchanger (30) and the fourth heat exchanger (40) are plate heat exchangers suitable for a vehicle-mounted horizontal cold box.

2. The vehicle-mounted mobile SMR-PHE natural gas liquefaction device according to claim 1, characterized in that: The fourth heat exchanger (40) is used to obtain LPG after heat exchange between the raw gas and the refrigerant. The raw gas NG and the refrigerant J enter the fourth heat exchanger (40) for heat exchange to obtain the raw gas a and the refrigerant L; The raw gas a enters the heavy hydrocarbon separator (50) to obtain liquid phase raw gas LPG and gas phase raw gas b.

3. The vehicle-mounted mobile SMR-PHE natural gas liquefaction device according to claim 1, characterized in that: The process of obtaining LNG by heat exchange between the raw gas and the refrigerant using the third heat exchanger (30) is as follows: The gaseous raw gas b and the refrigerant E enter the third heat exchanger (30) for heat exchange to obtain high-pressure liquefied natural gas c and refrigerant G; The high-pressure liquefied natural gas c is depressurized by the first throttle valve (60) to obtain low-pressure liquefied raw gas d, and the low-pressure liquefied raw gas d enters the gas-liquid separator (70) to obtain liquefied natural gas LNG and gasified natural gas BOG.

4. A vehicle-mounted mobile SMR-PHE natural gas liquefaction device according to claim 2 or 3, characterized in that: The first heat exchanger (10) and the second heat exchanger (20) are used for the refrigerant self-heat exchange process as follows: The high-pressure refrigerant U and the refrigerant I enter the first heat exchanger (10) for heat exchange, the high-pressure refrigerant U is cooled to obtain the refrigerant A, and the refrigerant I is reheated to obtain the refrigerant K; Refrigerant A and refrigerant D enter the second heat exchanger (20) for heat exchange, refrigerant A is cooled to obtain refrigerant B, and refrigerant D is reheated to obtain refrigerant F; The refrigerant B is depressurized by the second throttle valve (80) to obtain refrigerant C, and the refrigerant C is split by the second splitter (90) to obtain refrigerant D and refrigerant E; Refrigerant F and refrigerant G enter the second mixer (100) and are mixed to obtain refrigerant H, and refrigerant H is split by the first splitter (120) to obtain refrigerant J and refrigerant I; The refrigerant L and the refrigerant K enter the first mixer (110) and are mixed to obtain a low-pressure refrigerant M.

5. The vehicle-mounted mobile SMR-PHE natural gas liquefaction device according to claim 1, characterized in that: The refrigerant pressurization stage process is as follows: The low-pressure refrigerant M is compressed by the first-stage compressor (130) to obtain refrigerant N, and the refrigerant N is passed through the first water cooler (140) to obtain refrigerant O; Refrigerant O enters the separator (150) for gas-liquid separation to obtain gas-phase refrigerant P and liquid-phase refrigerant Q, wherein the gas-phase refrigerant P is compressed by the second-stage compressor (160) to obtain refrigerant R, and the liquid-phase refrigerant Q is pressurized by the liquid pump (170) to obtain refrigerant S, and the refrigerant R and the refrigerant S are mixed by the third mixer (180) to obtain refrigerant T; The refrigerant T passes through the second water cooler (190) to obtain high-pressure refrigerant U.

6. The vehicle-mounted mobile SMR-PHE natural gas liquefaction device according to claim 1, characterized in that: The refrigerant composition is: CH4 accounts for 29.12 mol%, C2H4 accounts for 27.53 mol%, C3H8 accounts for 8.42 mol%, i-C5H 12 It accounts for 21.87 mol%, and N2 accounts for 13.06 mol%.

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