A low temperature full containment tank with a low liquid level material extraction device

Abstract

The present invention provides a low-temperature full-volume tank with a low-liquid-level material extraction device, comprising an inner tank, an outer tank, an operating platform and a material extraction device capable of extracting low-liquid-level materials; the material extraction device comprises a material circulation tank and a cryogenic pump installed on the operating platform, a first venturi mixer installed at the bottom of the inner tank and corresponding connecting pipelines; the low-temperature medium in the material circulation tank can enter the first venturi mixer through the cryogenic pump and the introduction pipeline, so that the low-temperature medium in the inner tank can enter the first venturi mixer through the suction hole of the first venturi mixer under the action of pressure difference, and enter the material circulation tank through the outlet pipeline after mixing. The present invention can extract the low-liquid-level low-temperature medium in the pump column of the low-temperature full-volume tank that cannot be extracted by the submersible pump, reduce the ineffective volume of the low-temperature full-volume tank, and improve the volume utilization rate of the full-volume tank; the low-liquid-level material extraction device can also be used as a backup extraction facility other than the pump column.

Description

Technical Field

[0001] The invention relates to the technical field of cryogenic liquefied gas storage, and in particular to a cryogenic full-capacity tank with a low-liquid-level material extraction device. Background Art

[0002] Substances that are gaseous at normal temperature and pressure and can be liquefied after appropriate freezing can be stored safely and efficiently in low-temperature and normal-pressure storage tanks. Substances that meet this characteristic include hydrocarbons such as methane, ethylene, ethane, propylene, propane, butylene, butane, etc. involved in the petrochemical industry, and ammonia commonly used in the chemical industry. Methane is the main component of natural gas, and propane and butane are the main components of liquefied gas. A considerable proportion of them are used as industrial and civilian clean energy. As the world pays more attention to environmental issues, the consumption of clean energy such as liquefied hydrocarbons (Liquefied Hydrocarbon) and liquefied natural gas (Liquefied Natural Gas, hereinafter referred to as LNG) is increasing. In addition, the number and production scale of petrochemical enterprises that use hydrocarbons as raw materials for further deep processing are also increasing, and the demand for large cryogenic storage tanks for storing these clean energy and liquefied hydrocarbons is also rising.

[0003] For safety reasons, existing large-scale cryogenic full-volume storage tanks are not allowed to have holes in the tank wall and tank bottom, and the pipelines connected to the tanks are all top-in and top-out, that is, they enter and exit from the tank top. Due to the large diameter and height of the tank, the tank top space height plus the tank wall height is far greater than the suction vacuum height of the liquid, and the discharge pump can only work in the liquid mode, that is, a cryogenic submersible pump is used.

[0004] When starting, the cryogenic submersible pump requires sufficient cryogenic medium in the tank to ensure that the minimum liquid level is not lower than the minimum operable liquid level required by the cryogenic submersible pump. At present, the minimum operable liquid level of the cryogenic submersible pump is usually about 1.2m after adding a certain safety margin, that is, the 1.2m range at the bottom of the cryogenic full-capacity tank is usually the working "dead zone", resulting in a large ineffective working volume at the bottom of the tank. For example, 50000m 3 The inner diameter of the cryogenic storage tank is about 46m, the height is 1.2m and the volume is about 1994m 3 ; 80000m 3 The inner diameter of the cryogenic storage tank is about 59m, the height of 1.2m and the volume is about 3280m 3 ; 160000m 3 The inner diameter of the cryogenic storage tank is about 87m, and the volume is about 7134m at a height of 1.2m. 3 .

[0005] The materials in the invalid working volume at the bottom of the tank cannot be discharged out of the tank by the cryogenic submersible pump. If the storage tank needs to be shut down for maintenance, these bottom materials can only be discharged by vaporization, which consumes a lot of energy and takes a long time. Summary of the invention

[0006] The purpose of the present invention is to provide a low-temperature full-capacity tank with a low-liquid-level material extraction device to solve the problem in the prior art that the ineffective working volume at the bottom of the storage tank is too large and there is too much residual medium that cannot be extracted.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: a low-temperature full-capacity tank with a low-liquid-level material extraction device, comprising an inner tank, an outer tank surrounding the inner tank, and an operating platform arranged on the top of the outer tank; the low-temperature full-capacity tank also includes a material extraction device capable of extracting low-liquid-level materials; the material extraction device comprises: a material circulation tank, installed on the operating platform, in which a low-temperature medium is contained; a first venturi mixer, installed at the bottom of the inner tank; an inlet and an outlet at both ends thereof, and a suction hole is arranged on the outer periphery thereof; an introduction pipeline, which is introduced by the material circulation tank; The outlet of the ring tank is connected to the inlet of the first Venturi mixer; the outlet of the first Venturi mixer is connected to the inlet of the material circulation tank through the outlet of the first Venturi mixer; a cryogenic pump is installed on the operating platform and connected to the introduction pipeline; when the medium is extracted, the low-temperature medium in the material circulation tank enters the first Venturi mixer through the cryogenic pump and the introduction pipeline, so that the low-temperature medium in the inner tank can enter the first Venturi mixer through the suction hole under the action of the pressure difference, and enter the material circulation tank through the outlet pipeline after mixing.

[0008] Wherein, the first Venturi mixer includes a contraction section, a throat section and a diffusion section connected in sequence; the large end opening of the contraction section serves as an inlet and is connected to the introduction pipeline; the large end opening of the diffusion section serves as an outlet and is connected to the outlet pipeline; the two ends of the throat section are respectively connected to the small end opening of the contraction section and the small end opening of the diffusion section; the suction hole is opened corresponding to the outer periphery of the throat section and is connected to the inside of the throat section; the first Venturi mixer is placed horizontally in the inner tank.

[0009] Wherein, the first Venturi mixer also includes a suction chamber arranged around the periphery of the throat section and communicating with the interior of the throat section; the two ends of the suction chamber are respectively connected to the outer wall of the contraction section and the outer wall of the diffusion section; the suction hole is provided on the outer peripheral wall of the suction chamber.

[0010] Wherein, the suction hole is opened on the outer peripheral wall of the throat section; the first Venturi mixer also includes a suction pipe correspondingly arranged at the suction hole, and the suction pipe is communicated with the interior of the inner tank.

[0011] Among them, the material circulation tank is also provided with a medium output port for outputting low-temperature medium to the outside, and a liquid level control mechanism is provided to control the opening and closing of the medium output port when a preset liquid level is reached. The preset liquid level is higher than the liquid level required for the operation of the cryogenic pump when the medium is extracted.

[0012] Wherein, the liquid level control mechanism is an overflow weir arranged in the material circulation tank; the outlet of the material circulation tank is communicated with the internal space of the overflow weir, and the medium output port is communicated with the space outside the overflow weir.

[0013] Wherein, the liquid level control mechanism is an overflow port arranged on the side wall of the material circulation tank, the height of the overflow port is higher than the outlet of the material circulation tank, and the overflow port is communicated with the medium output port.

[0014] Wherein, the liquid level control mechanism includes an electrically connected liquid level meter and a switch valve, the liquid level meter is used to detect the liquid level in the material circulation tank, and the switch valve is correspondingly arranged at the medium output port.

[0015] Wherein, a control valve is provided on the inlet pipeline to adjust the flow in the inlet pipeline, and the control valve is located outside the outer tank; the cryogenic pump is located between the material circulation tank and the control valve.

[0016] Wherein, the material extraction device also includes a pressurizing unit, and the pressurizing unit is arranged on the lead-out pipeline to increase the power of the low-temperature medium flowing to the material circulation tank.

[0017] Wherein, the pressurizing unit includes: a second Venturi mixer, whose suction hole and outlet are connected in series to the lead-out pipeline; a pressurizing inlet pipeline, connecting the inlet of the second Venturi mixer and the outlet of the material circulation tank; and a pressurizing control valve, which is arranged on the pressurizing inlet pipeline to adjust the flow in the pressurizing inlet pipeline.

[0018] It can be seen from the above technical scheme that the present invention has at least the following advantages and positive effects: the low-temperature full-capacity tank of the present invention is equipped with a material extraction device that can extract low-liquid-level materials, wherein the material extraction device includes a material circulation tank and a cryogenic pump located on the tank top operating platform, a Venturi mixer located at the bottom of the inner tank, and corresponding connecting pipelines. The low-temperature medium in the material circulation tank enters the Venturi mixer through the cryogenic pump. According to the Bernoulli principle and the principle of momentum transfer, the low-temperature medium will form a local low-pressure and high-speed flow entrainment effect in the Venturi mixer, so that the low-temperature medium in the inner tank enters the Venturi mixer through the suction hole under the action of the pressure difference, and the mixed low-temperature medium returns to the material circulation tank together. During the circulation process, the flow rate of the low-temperature medium returning to the material circulation tank is greater than the flow rate of the low-temperature medium pumped out from the material circulation tank, and the difference is the extracted low-temperature medium.

[0019] The material extraction device is mainly used as a supplementary discharge measure after the submersible pump in the cryogenic full-volume tank is pumped to the lowest liquid level and stops. Through this extraction device, the low-liquid-level cryogenic medium originally in the working "dead zone" can be extracted, and the cryogenic medium above the liquid level of the suction hole of the venturi mixer can be extracted by the material extraction device, so that the liquid level of the cryogenic full-volume tank can be lowered to the position of the suction hole or the suction pipe mouth of the first venturi mixer. The liquid level height is significantly lower than the minimum operable liquid level height required by the submersible pump of the prior art, thereby significantly reducing the ineffective volume of the cryogenic full-volume tank and improving the volume utilization rate of the full-volume tank. Under the condition of the same tank size, the effective working volume of the full-volume tank can be increased. When the effective working volume is constant, the height of the inner and outer tanks can be reduced to save engineering investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of an embodiment of a low-temperature full-containment tank of the present invention.

[0021] Figure 2 yes Figure 1 Schematic diagram of the structure of the material extraction device.

[0022] Figure 3 yes Figure 2 Schematic diagram of the principle of mixing medium and low temperature media in the first venturi mixer.

[0023] Figure 4 It is a structural schematic diagram of another embodiment of the low-temperature full-containment tank of the present invention.

[0024] Figure 5 yes Figure 4 Schematic diagram of the structure of the material extraction device.

[0025] Figure 6 It is a schematic diagram of the structure of another type of Venturi mixer.

[0026] The reference numerals are as follows: 1, inner tank; 2, outer tank; 3, operating platform; 4, pump column; 5, submersible pump; 6 / 6a, material extraction device; 61 / 61a, material circulation tank; 6101 / 6101a, outlet; 6102 / 6102a, inlet; 6103 / 6103a, medium output port; 6104a, overflow port; 611, overflow weir; 62, first venturi mixer; 621, contraction section; 622 / 622b, throat section; 623, diffusion section; 624, suction chamber; 6 2b, Venturi mixer; 625b, suction pipe; 6201, inlet; 6202 / 6202b, suction hole; 6203, outlet; 63, introduction pipeline; 64 / 64a, lead-out pipeline; 641a, first lead-out section; 642a, second lead-out section; 65, cryogenic pump; 66, control valve; 67, pressurization unit; 671, second Venturi mixer; 6711, inlet; 6712, suction hole; 6713, outlet; 672, pressurization introduction pipeline; 673, pressurization control valve. DETAILED DESCRIPTION

[0027] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0028] The present invention provides a low-temperature full-containment tank for storing liquefied low-temperature media, which can be hydrocarbons such as methane, ethylene, ethane, propylene, propane, butylene, butane, etc., or ammonia commonly used in the chemical industry.

[0029] See also Figure 1 The low-temperature full-containment tank provided in this embodiment generally includes an inner tank 1 for storing a low-temperature medium, an outer tank 2 surrounding the inner tank 1, an operating platform 3 arranged on the top of the outer tank 2, a pump column 4 penetrating from the top of the outer tank 2 to the bottom of the inner tank 1, a submersible pump 5 arranged in the pump column 4, and a material extraction device 6 for extracting low-liquid-level materials from the bottom of the inner tank 1.

[0030] The inner tank 1 and the outer tank 2 generally include a horizontally arranged bottom plate and a cylinder body erected on the bottom plate, and an insulation layer is arranged between the bottom plates of the inner tank 1 and the outer tank 2 and between the cylinder bodies. The top of the outer tank 2 has an arch and a top plate suspended under the arch, and an insulation layer is also arranged between the arch and the top plate. The top plate is softly sealed to the inner tank 1. The pump column 4 passes through the top of the outer tank 2 and extends into the bottom of the inner tank 1. The submersible pump 5 is installed at the bottom of the pump column 4 and immersed in the low-temperature medium of the inner tank 1, and is used to transport the low-temperature medium in the inner tank 1 to the outside through the pump column 4. The operating platform 3 is fixed to the top of the outer tank 2, which can be used to accommodate various pipeline valves, working accessories, etc. equipped with the low-temperature full-capacity tank, and for operators to perform work and maintenance on it.

[0031] Compared with the cryogenic full-volume tank of the prior art, the cryogenic full-volume tank of this embodiment is equipped with a material extraction device 6, which is used as a supplementary discharge measure after the submersible pump 5 stops pumping to the lowest liquid level L1, so as to reduce the ineffective volume of the cryogenic full-volume tank. It is worth mentioning that the material extraction device 6 involved in the present invention can not only extract low-level materials (i.e., low-temperature media below the lowest operable liquid level L1 of the submersible pump 5), but also can operate within the liquid level range in which the submersible pump 5 in the pump column 4 can work. Therefore, in some cases, it can also be used as a small flow output backup facility other than the submersible pump 5. The following will be combined with Figure 2 The material extraction device 6 is mainly introduced in detail, and other specific structures of the inner tank 1, the outer tank 2, the operating platform 3, the pump column 4, and the submersible pump 5 can refer to the structure of the full-containment tank related technology, which will not be described in detail here.

[0032] See also Figure 1 and Figure 2 The material extraction device 6 of this embodiment includes a material circulation tank 61, a first venturi mixer 62, an inlet pipeline 63, an outlet pipeline 64 and a cryogenic pump 65. Furthermore, a control valve 66 is also provided on the inlet pipeline 63.

[0033] The material circulation tank 61 in this embodiment is a horizontal low-temperature tank, which is installed on the operating platform 3. The interior of the material circulation tank 61 is used to contain low-temperature medium, and the exterior of the material circulation tank 61 can be wrapped with cold preservation materials.

[0034] by Figure 2 As a reference, an overflow weir 611 is provided in the material circulation tank 61. The overflow weir 611 divides the internal space of the material circulation tank 61 into two parts. When the low-temperature medium in the overflow weir 611 (i.e., the left side of the overflow weir 611 in the figure) exceeds the height of the overflow weir 611, the low-temperature medium overflows the overflow weir 611 (i.e., the right side of the overflow weir 611 in the figure). The space on the left side of the overflow weir 611 should meet the circulation volume requirements of the low-temperature medium required for medium extraction, and the height of the overflow weir 611 should meet the requirements of the minimum operating liquid level of the cryogenic pump 65. On this basis, the height of the overflow weir 611 is set according to actual conditions.

[0035] An outlet 6101 is provided at the bottom of the left end of the material circulation tank 61. The outlet 6101 is communicated with the space surrounded by the overflow weir 611 and is used to output the low-temperature medium when the medium is extracted.

[0036] A medium outlet 6103 is also provided at the bottom of the right end of the material circulation tank 61. The medium outlet 6103 communicates with the space outside the overflow weir 611 in the material circulation tank 61 and is used to output the low-temperature medium to the outside.

[0037] An inlet 6102 is provided on the left side of the top of the material circulation tank 61 for receiving low-temperature medium.

[0038] The first venturi mixer 62 is horizontally placed on the bottom plate of the inner tank 1, so as to have a lower installation height. The first venturi mixer 62 is a liquid-liquid mixer, which mainly includes a contraction section 621, a throat section 622 and a diffusion section 623 connected in sequence. In this embodiment, the first venturi mixer 62 further has a suction chamber 624.

[0039] The contraction section 621 and the diffusion section 623 are both hollow structures with gradually changing cross sections. The large end opening of the contraction section 621 serves as the inlet 6201 of the first venturi mixer 62, and the large end opening of the diffusion section 623 serves as the outlet 6203 of the first venturi mixer 62. One end of the throat section 622 is connected to the small end opening of the contraction section 621, and the other end is aligned with the small end opening of the diffusion section 623.

[0040] The suction chamber 624 is arranged around the periphery of the throat section 622, forming a double-chamber structure at the throat section 622. The two ends of the suction chamber 624 are respectively connected to the outer wall of the contraction section 621 and the outer wall of the diffusion section 623. The outer peripheral wall of the suction chamber 624 is provided with a plurality of suction holes 6202, which are communicated with the interior of the inner tank 1 so that the low-temperature medium in the inner tank 1 can be sucked into the suction chamber 6222. An annular cavity is formed between the suction chamber 624 and the throat 622, and the suction chamber 624 is communicated with the interior of the throat section 622, and the low-temperature medium in the suction chamber 624 can further enter the throat section 622.

[0041] The introduction pipeline 63 passes through the top of the outer tank 2, and is connected to the inlet 6201 of the first venturi mixer 62 from the outlet 6101 of the material circulation tank 61, so as to introduce the low-temperature medium in the material circulation tank 61 into the first venturi mixer 62 for extraction operation.

[0042] The outlet pipe 64 also passes through the top of the outer tank 2 , and is connected to the inlet 6102 of the material circulation tank 61 through the outlet 6203 of the first venturi mixer 62 , so as to lead the low-temperature medium in the first venturi mixer 62 to the material circulation tank 61 .

[0043] The cryopump 65 is installed on the operating platform 3 and connected to the inlet pipe 63 to provide power for the cryogenic medium to flow. The cryopump 65 is a non-submersible pump, that is, it does not need to be immersed in the cryogenic medium, and it can be a non-submersible pump of any structural form.

[0044] The control valve 66 is arranged on the inlet pipe 63 to control the on-off of the inlet pipe 63 and to adjust the flow rate of the cryogenic medium in the inlet pipe 63. The control valve 66 is located downstream of the cryogenic pump 65 but outside the outer tank 2.

[0045] The material circulation tank 61, the first venturi mixer 62, the inlet pipe 63, the outlet pipe 64, the cryogenic pump 65 and the control valve 66 are all required to be able to withstand the temperature of the extracted cryogenic medium and are manufactured using cryogenic materials that can withstand the corresponding temperature.

[0046] Combined Figure 2 and Figure 3 The working principle of the material extraction device 6 is as follows: when extracting the medium, the low-temperature medium in the material circulation tank 61 is driven by the power of the low-temperature pump 65 and enters the first venturi mixer 62 through the introduction pipe 63. For ease of understanding, this part of the low-temperature medium introduced from the material circulation tank 61 to the first venturi mixer 62 is called the initial low-temperature medium F0. According to the Bernoulli principle (energy conservation) and the momentum transfer principle (momentum conservation), after the initial low-temperature medium F0 enters the first venturi mixer 62, in the process of flowing from the contraction section 621 to the throat section 622, due to the decrease in the flow cross-sectional area, the flow velocity increases, and the pressure decreases, thereby forming a local low pressure and high-speed flow entrainment effect at the throat section 622, so that the low-temperature medium Fi in the inner tank 1 enters through the suction hole 6202 under the action of the pressure difference.

[0047] In the first venturi mixer 62, the sucked low-temperature medium Fi is mixed with the initial low-temperature medium F0, and the mixed low-temperature medium Fm enters the material circulation tank 61 through the outlet pipe 64 due to the increase of the flow cross-sectional area in the diffusion section 623, the flow velocity is reduced, and the pressure is increased. In this embodiment, the throat section 622 of the first venturi mixer 62 is also provided with a suction chamber 624, and the low-temperature medium in the inner tank 1 is first sucked into the suction chamber 624, and then enters the throat section 622 for mixing, which can more effectively utilize the momentum of the initial low-temperature medium F0, so that the mixed low-temperature medium can flow back to the material circulation tank 61 more smoothly.

[0048] The flow rate of the low-temperature medium reaching the material circulation tank 61 is greater than the initial flow rate of the low-temperature medium pumped from the material circulation tank 61 into the first venturi mixer 62, and the excess portion is the low-temperature medium extracted from the inner tank 1. Through the above continuous circulation process, the low-temperature medium in the inner tank 1 can be continuously extracted into the material circulation tank 61.

[0049] The low-temperature medium located in the overflow weir 611 in the material circulation tank 61 is used to maintain the medium extraction operation. When the low-temperature medium in the material circulation tank 61 exceeds the overflow weir 611, the low-temperature medium exceeding the height of the overflow weir 611 can be transported outward through the medium output port 6103.

[0050] See also Figure 4 and Figure 5 In another embodiment of the cryogenic full-containment tank, the material extraction device 6a is further provided with a pressurizing unit 67 on the basis of the aforementioned embodiment. The pressurizing unit 67 is arranged on the lead-out pipeline 64, and is used to increase the power of the mixed cryogenic medium to flow toward the material circulation tank 61a, so that the cryogenic medium can flow back to the material circulation tank 61a more smoothly. It is suitable for situations with a large extraction height, such as a cryogenic full-containment tank with a large height.

[0051] In this embodiment, the pressurizing unit 67 includes a second venturi mixer 671 , a pressurizing introduction pipeline 672 and a pressurizing control valve 673 .

[0052] The composition structure of the second venturi mixer 671 may be the same as that of the first venturi mixer 62. The suction hole 6712 and the outlet 6713 of the second venturi mixer 671 are connected in series to the lead-out pipeline 64a. Specifically, the lead-out pipeline 64a is divided into a first lead-out section 641a and a second lead-out section 642a. The first lead-out section 641a connects the outlet 6203 of the first venturi mixer 62 and the suction hole 6712 of the second venturi mixer 671. The second lead-out section 642a connects the outlet 6713 of the second venturi mixer 671 and the inlet 6102a of the material circulation tank 61a.

[0053] The pressurized introduction pipeline 672 connects the inlet 6711 of the second venturi mixer 671 and the outlet 6101a of the material circulation tank 61a, so as to introduce a certain amount of initial low-temperature medium from the material circulation tank 61a into the second venturi mixer 671. The initial low-temperature medium is further mixed with the mixed low-temperature medium coming out of the first venturi mixer 62 in the second venturi mixer 671 to increase the pressure, so that the low-temperature medium has greater power to return to the material circulation tank 61a from the second lead-out section 642a.

[0054] The pressurization control valve 673 is arranged on the pressurization introduction pipeline 672 . On the one hand, it controls the on-off of the pressurization introduction pipeline 672 , and on the other hand, it also adjusts the flow in the pressurization introduction pipeline 672 .

[0055] Similar to the previous embodiment, the second venturi mixer 671, the pressurization introduction pipeline 672 and the pressurization control valve 673 are also required to be able to withstand the temperature of the extracted low-temperature medium and are made of low-temperature materials that can withstand the corresponding temperature.

[0056] This embodiment uses a second venturi mixer 671 to increase the power of the reflux low-temperature medium to form a two-stage series extraction process. In other embodiments, if the extraction height is higher and the reflux power is insufficient, more venturi mixers can be connected in series on the lead-out pipeline 64 / 64a to form a multi-stage series extraction process, and the connection method of the multi-stage series extraction can be deduced by analogy.

[0057] Compared with the previous embodiment, another difference of this embodiment is that the material circulation tank 61a adopts a vertical storage tank. The inlet 6102a of the material circulation tank 61a is located at the top, and the outlet 6101a of the material circulation tank 61a is located on the side wall near the bottom. The material circulation tank 61a is not provided with an overflow weir 611, but an overflow port 6104a is provided on the side wall of the material circulation tank 61a. The height of the overflow port 6104a is higher than the outlet 6101a of the material circulation tank 61a, and higher than the liquid level required for medium extraction, and the medium output port 6103a is connected and led out from the overflow port 6104a.

[0058] The structural form of the vertical material circulation tank 61a is also applicable to the material extraction device 6 in the previous embodiment.

[0059] In the above two embodiments, the material circulation tank 61 / 61a respectively adopts the structure of overflow weir 611 and overflow port 6104a to form a liquid level control mechanism to control the opening and closing of the medium outlet 6103 / 6103a when the preset liquid level is reached. In other embodiments not shown, the liquid level control mechanism may also include an electrically connected liquid level meter and a switch valve, the liquid level meter is used to detect the liquid level in the material circulation tank, and the switch valve is correspondingly arranged at the medium outlet.

[0060] See also Figure 6 The Venturi mixer 62 / 671 in the above embodiments can also be replaced by Figure 6 The structural form shown. Figure 6In the structure shown, the venturi mixer 62b is not equipped with a suction chamber 624, but a plurality of suction holes 6202b are provided on the outer peripheral wall of the throat section 622b, and a suction pipe 625b is provided corresponding to each suction hole 6202b. After the initial low-temperature medium F0 is introduced into the contraction section 621 of the venturi mixer 62b, under the action of the pressure difference, the low-temperature medium Fi in the inner tank 1 can be guided into the throat section 622b by the suction pipe 625b, and mixed with the initial low-temperature medium Fi, and the mixed low-temperature medium Fm is then led out to the next process.

[0061] In some other embodiments not shown, the suction pipe 625b can also be removed, and the low-temperature medium Fi in the inner tank 1 is directly sucked in through the suction hole 6202b on the outer peripheral wall of the throat section 622b. In addition, for the structure of the first venturi mixer 62 of the above embodiment, a suction pipe can also be added at the suction hole 6202 of the suction chamber 624. Similarly, a suction pipe can also be added at the suction hole 6712 of the second venturi mixer 671.

[0062] Based on the above introduction, when the cryogenic full containment tank in each embodiment of the present invention is working normally, the cryogenic medium is output to the outside through the pump column 4 by the power of the submersible pump 5. According to the minimum operable liquid level required for the submersible pump 5 to start and maintain operation, the submersible pump 5 can reduce the liquid level in the cryogenic full containment tank to the minimum level of Figure 1 and Figure 3 At L1 as shown in the figure, according to the requirements of the general submersible pump 5 in the prior art, L1 is approximately 1.2m. When the liquid level in the cryogenic full-volume tank drops to L1 and the submersible pump 5 stops, if it is necessary to further extract the cryogenic medium from the inner tank 1, the material extraction device 6 / 6a is used. The material extraction device 6 / 6a continuously extracts the cryogenic medium at the bottom of the inner tank 1 according to the working principle described above until the liquid level drops to the first venturi mixer 62, at which time the liquid level is at L2. The L2 can be approximately 0.2m to 0.3m. Compared with L1 of 1.2m, the liquid level in the inner tank 1 can be reduced by about 1m, which significantly reduces the ineffective volume of the cryogenic full-volume tank and improves the volume utilization rate of the cryogenic full-volume tank.

[0063] In the low-temperature full-containment tank, the power part and the control part of the material extraction device 6 / 6a are both arranged outside the outer tank 2. Except for the Venturi mixer 62 / 671 / 62b and the pipeline part which need to be immersed in the low-temperature medium, no other equipment or cables are immersed in the low-temperature medium. The components inside the tank can achieve maintenance-free operation throughout the life cycle of the tank.

[0064] It is worth mentioning that when the low-temperature full-containment tank operates at a liquid level higher than L1, the material circulation tank 61 / 61a of the material extraction device 6 / 6a does not need to store low-temperature medium. When low-liquid-level medium extraction is required, a certain amount of low-temperature medium is filled into the material circulation tank 61 / 61a as the initial power flow.

[0065] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A low-temperature full-containment tank with a low-liquid-level material extraction device, comprising an inner tank, an outer tank surrounding the inner tank, and an operating platform arranged on the top of the outer tank; characterized in that: The low-temperature full-containment tank also includes a material extraction device capable of extracting low-liquid-level materials; the material extraction device includes: A material circulation tank is installed on the operating platform and is used to contain low-temperature medium; A first venturi mixer is installed at the bottom of the inner tank; its two ends are an inlet and an outlet respectively, and its outer periphery is provided with a suction hole; An introduction pipeline is connected from the outlet of the material circulation tank to the inlet of the first venturi mixer; A lead-out pipeline is connected from the outlet of the first venturi mixer to the inlet of the material circulation tank; A cryogenic pump, installed on the operating platform and connected to the introduction pipeline; When the medium is extracted, the low-temperature medium in the material circulation tank enters the first venturi mixer through the low-temperature pump and the inlet pipeline, so that the low-temperature medium in the inner tank can enter the first venturi mixer through the suction hole under the action of the pressure difference, and enter the material circulation tank through the outlet pipeline after mixing; The material extraction device further comprises a pressurizing unit, which is arranged on the outlet pipeline and comprises: A second venturi mixer, the suction port and the outlet of which are connected in series to the outlet pipeline; A pressurized introduction pipeline is connected to the inlet of the second venturi mixer and the outlet of the material circulation tank; A pressurization control valve is arranged on the pressurization introduction pipeline to adjust the flow rate in the pressurization introduction pipeline; The pressurizing unit is close to the middle of the inner tank in the height direction. A certain initial low-temperature medium is introduced into the second venturi mixer from the material circulation tank. The initial low-temperature medium is further mixed with the mixed low-temperature medium coming out of the first venturi mixer in the second venturi mixer to increase the pressure in the outlet pipeline. The pressurizing unit can increase the power of the low-temperature medium flowing into the material circulation tank to increase the lifting height.

2. The cryogenic full containment tank according to claim 1, characterized in that: The first Venturi mixer includes a contraction section, a throat section and a diffusion section connected in sequence; the large end opening of the contraction section serves as an inlet and is connected to the introduction pipeline; the large end opening of the diffusion section serves as an outlet and is connected to the outlet pipeline; the two ends of the throat section are respectively connected to the small end opening of the contraction section and the small end opening of the diffusion section; the suction hole is opened corresponding to the outer periphery of the throat section and is connected to the inside of the throat section; the first Venturi mixer is placed horizontally in the inner tank.

3. The cryogenic full containment tank according to claim 2, characterized in that: The first Venturi mixer also includes a suction chamber arranged around the periphery of the throat section and communicating with the interior of the throat section; two ends of the suction chamber are respectively connected to the outer wall of the contraction section and the outer wall of the diffusion section; the suction hole is provided on the outer peripheral wall of the suction chamber.

4. The cryogenic full containment tank according to claim 2, characterized in that: The suction hole of the first venturi mixer is provided on the outer peripheral wall of the throat section; The first venturi mixer also includes a suction pipe corresponding to the suction hole, and the suction pipe is communicated with the interior of the inner tank.

5. The cryogenic full containment tank according to claim 1, characterized in that: The material circulation tank is also provided with a medium outlet for outputting low-temperature medium to the outside, and a liquid level control mechanism is provided to control the opening and closing of the medium outlet when a preset liquid level is reached. The preset liquid level is higher than the liquid level required for the operation of the cryogenic pump when the medium is extracted.

6. The cryogenic full containment tank according to claim 5, characterized in that: The liquid level control mechanism is an overflow weir arranged in the material circulation tank; the outlet of the material circulation tank is communicated with the internal space of the overflow weir, and the medium output port is communicated with the space outside the overflow weir.

7. The cryogenic full containment tank according to claim 5, characterized in that: The liquid level control mechanism is an overflow port arranged on the side wall of the material circulation tank. The height of the overflow port is higher than the outlet of the material circulation tank, and the overflow port is communicated with the medium output port.

8. The cryogenic full containment tank according to claim 5, characterized in that: The liquid level control mechanism includes an electrically connected liquid level meter and a switch valve, wherein the liquid level meter is used to detect the liquid level in the material circulation tank, and the switch valve is correspondingly arranged at the medium output port.

9. The cryogenic full containment tank according to claim 1, characterized in that: The inlet pipeline is provided with a control valve to adjust the flow in the inlet pipeline, and the control valve is located outside the outer tank; the cryogenic pump is located between the material circulation tank and the control valve.

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