Hydrogen and hydrogen isotope enriching and liquefying system

Abstract

The invention belongs to the technical field of hydrogen and isotope separation, and particularly relates to a hydrogen and hydrogen isotope enriching and liquefying system. Comprising three stages of cooling and liquefying units connected in series and an isotope enrichment system, the first-stage cooling unit comprises a first-stage ortho-parahydrogen converter and a first-stage liquefying cooler, and a high-pressure expansion machine is configured; the second-stage cooling unit comprises a second-stage ortho-parahydrogen converter and a second-stage liquefaction cooler, and is provided with a medium-pressure expansion machine; the third-stage cooling unit comprises a third-stage ortho-parahydrogen converter and a third-stage liquefaction cooler, and is provided with a low-pressure expansion machine; the isotope enrichment system comprises a three-stage isotope enrichment device, an isotope enrichment tank and a liquid hydrogen tank which are connected in series, and a closed loop is formed by a liquid hydrogen expansion valve and a three-stage liquefaction cooler. According to the invention, parahydrogen after passing through each stage of ortho-parahydrogen converter cannot be converted into ortho-hydrogen again due to temperature rise, and low-temperature cold hydrogen generated by isentropic expansion of the high-pressure turbo expander absorbs heat generated by conversion of ortho-hydrogen into parahydrogen of product hydrogen after hydrogen refrigeration after ortho-parahydrogen conversion.

Description

Technical Field

[0001] This invention patent belongs to the technical field of hydrogen and isotope separation, and particularly relates to a hydrogen and hydrogen isotope enrichment liquefaction system. Background Art

[0002] According to different hydrogen atom masses, it can be divided into 3 isotopes with atomic weights of 1 protium (H, hydrogen), 2 deuterium (D, heavy hydrogen), and 3 tritium (T, superheavy hydrogen) respectively. Most of the physical and chemical properties of deuterium are similar to those of hydrogen. In most cases, the reactivity of deuterium is slightly less than that of protium. Deuterium is mainly used in the form of heavy water and deuterium gas. The boiling point of deuterium is 23.5K, the boiling point of hydrogen is 20.38K, and the boiling point of HD is 22.13K. Deuterium is an important element in nuclear physics and has been practically applied in the research and development of nuclear reactors. At present, the separation of deuterium gas and protium gas mostly uses a low-temperature rectification system to realize the preparation of deuterium gas.

[0003] Currently, the preparation technologies of deuterium gas include: liquid hydrogen rectification technology, heavy water electrolysis technology, and gas chromatography. The liquid hydrogen rectification technology first concentrates HD, and then continues to rectify and concentrate after being converted into D2, HD, and H2 equilibrium through a catalyst. The heavy water electrolysis technology uses deuterium oxides of alkali metals as electrolytes or solid polymer electrolyzes heavy water. The prepared deuterium gas has high purity, but still needs further purification, mainly to reduce the protium gas in the deuterium gas, and the treatment process is very complex. The methods for purifying hydrogen isotopes by gas chromatography include H2-displacement chromatography, frontal chromatography, elution chromatography, and self-displacement chromatography. The H2-displacement chromatography has a large production capacity, the highest recovery rate and concentration rate, but the process is relatively complex.

[0004] Currently, the production methods of hydrogen isotopes include methods such as electrolysis after heavy water centrifugal separation, liquid hydrogen rectification method, and gas chromatography. The above methods are all purified at a relatively high purity, and a relatively high purity in the production process needs to be concentrated from a relatively low purity. Hydrogen isotopes account for approximately 1 / 6500 (about 0.015%) in natural hydrogen. For the separation of deuterium elements in natural hydrogen, the purification difficulty is very high, and the existing methods for preparing hydrogen isotopes have relatively high energy consumption. With the current increase in hydrogen production capacity and the booming development of liquid hydrogen projects, if hydrogen isotopes can be separated and purified through a low-temperature liquefaction process, the production capacity of hydrogen isotopes can be increased, and at the same time, the added value of the hydrogen industry can be improved. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydrogen liquefaction and hydrogen isotope enrichment liquefaction system, which can concentrate the isotopes in hydrogen from a low content to a high content, and improve the added value of the hydrogen industry.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] The present invention provides a hydrogen and hydrogen isotope enrichment liquefaction system, which is characterized in that it includes: a three-stage series cooling and liquefaction unit and an isotope enrichment system, wherein:

[0008] The first-stage cooling unit includes a first-stage ortho-para hydrogen converter and a first-stage liquefaction cooler, and a high-pressure expander is configured in this unit;

[0009] The second-stage cooling unit includes a second-stage ortho-para hydrogen converter and a second-stage liquefaction cooler, and a medium-pressure expander is configured;

[0010] The third-stage cooling unit includes a third-stage ortho-para hydrogen converter and a third-stage liquefaction cooler, and a low-pressure expander is configured;

[0011] The circulation pipeline network connects the outlets of each stage of expander to the system inlet;

[0012] The isotope enrichment system includes three-stage isotope enrichers connected in series, an isotope enrichment tank and a liquid hydrogen tank, and forms a closed-loop circuit with the third-stage liquefaction cooler through a liquid hydrogen expansion valve.

[0013] Further, a refrigeration regulating valve for the ortho-para hydrogen converter is provided at the refrigeration end of the first-stage ortho-para hydrogen converter, and its outlet is connected to the high-pressure expander through the high-pressure expander inlet pipeline.

[0014] Further, a second-stage refrigeration regulating valve for the ortho-para hydrogen converter is provided at the refrigeration end of the second-stage ortho-para hydrogen converter, and its outlet is connected to the medium-pressure expander through the medium-pressure expander inlet pipeline.

[0015] Further, a third-stage refrigeration regulating valve for the ortho-para hydrogen converter is provided at the refrigeration end of the third-stage ortho-para hydrogen converter, and its outlet is connected to the low-pressure expander through the low-pressure expander inlet pipeline.

[0016] Further, the first-stage cooling unit and the second-stage cooling unit are respectively placed in cold boxes with high-vacuum insulation.

[0017] Further, the three-stage isotope enrichers, the three-stage isotope enrichment coolers, the isotope enrichment tank, the third-stage liquefaction cooler, the liquid hydrogen expansion valve, and the liquid hydrogen tank are integrated in corresponding cold boxes with high-vacuum insulation.

[0018] The inlet of the present invention is high-pressure hydrogen at 76 - 90K after precooling, with a pressure between 1 Mpa and 20 Mpa, which enters the system through a cryogenic high-pressure pipeline. The cryogenic hydrogen passes through a primary ortho-para hydrogen converter, a primary liquefaction cooler, a secondary ortho-para hydrogen converter, a secondary liquefaction cooler, a tertiary ortho-para hydrogen converter, and a tertiary isotope enrichment cooler to cool the cryogenic hydrogen to slightly below the hydrogen liquefaction temperature, enlarge the isotope droplets and connect them to an isotope enrichment tank. The resulting cryogenic hydrogen is further depressurized after heat exchange through a tertiary liquid hydrogen cooler, and the formed liquid hydrogen is connected to a liquid hydrogen storage tank. Among them, the gases volatilized from the isotope enricher and the liquid hydrogen storage tank are collected and incorporated into the circulation pipeline.

[0019] Each ortho-para hydrogen converter has a hydrogen refrigeration function to ensure that the temperature of the hydrogen after heat exchange basically does not increase. The ortho-para hydrogen converter catalyzes ortho-hydrogen into para-hydrogen, which is beneficial for subsequent hydrogen liquefaction. Among them, the ortho-para hydrogen heat exchange valve controls the flow rate of the cryogenic high-pressure hydrogen in the heat exchange gas path.

[0020] The input end of the expander is high-pressure cryogenic hydrogen after heat exchange. According to different working conditions of enriched isotopes, the output end pressure is also different, and the output end pressure is controlled between 1 bar and 30 bar.

[0021] The advantages and positive effects of the present invention are:

[0022] 1. The structure is compact. The para-hydrogen after each ortho-para hydrogen converter will not be reconverted into ortho-hydrogen due to temperature rise. The low-temperature cold energy hydrogen generated by the isentropic expansion of the high-pressure turbine expander cools the hydrogen after ortho-para hydrogen conversion and absorbs the heat of the conversion of the product hydrogen from ortho-hydrogen to para-hydrogen.

[0023] 2. This device can self-adjust to achieve the liquefaction of liquid hydrogen and isotopes, and at the same time enrich trace isotopes in hydrogen.

[0024] 3. The process flow is simple, and it can achieve the enrichment of isotopes in high-pressure and low-pressure hydrogen. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of a hydrogen and isotope enrichment liquefaction system.

[0026] Low-temperature and high-pressure hydrogen pipeline 1, inlet pipeline 1-1 of the first-stage ortho-para hydrogen converter, refrigeration regulating valve 1-2 of the first-stage ortho-para hydrogen converter, first-stage ortho-para hydrogen converter 2, inlet pipeline 2-1 of the high-pressure expander, high-pressure expander 2-2, outlet pipeline 2-3 of the high-pressure expander, first-stage liquefaction cooler 3, inlet pipeline 3-1 of the second-stage ortho-para hydrogen converter, refrigeration regulating valve 3-2 of the second-stage ortho-para hydrogen converter, second-stage ortho-para hydrogen converter 4, inlet pipeline 4-1 of the medium-pressure expander, medium-pressure expander 4-2, outlet pipeline 4-3 of the medium-pressure expander, second-stage liquefaction cooler 5, inlet pipeline 5-1 of the third-stage ortho-para hydrogen converter, refrigeration regulating valve 5-2 of the third-stage ortho-para hydrogen converter, third-stage ortho-para hydrogen converter 6, inlet pipeline 6-1 of the low-pressure expander, low-pressure expander 6-2, outlet pipeline 6-3 of the low-pressure expander, third-stage isotope enricher 7, third-stage isotope enrichment cooler 7-1, lean isotope hydrogen pipeline 7-2, rich isotope liquid hydrogen pipeline 7-3, isotope enrichment tank 8, exhaust pipeline 8-1 of the isotope enrichment tank, third-stage liquefaction cooler 9, hydrogen outlet pipeline 9-1 of the third-stage liquefaction cooler, liquid hydrogen expansion valve 10, liquid hydrogen tank 11, exhaust pipeline 11-1 of the liquid hydrogen tank, circulation pipe network 12.

[0027] Specific implementation content

[0028] The present invention is described in detail below through specific embodiments. The embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby. The ortho-para hydrogen converter, hydrogen cooler, and refrigeration expander are determined to perform first-stage, second-stage, and third-stage operations according to the ortho-para hydrogen catalyst, the heat exchanger effect, and the refrigeration effect of the expander. This example is not limited to coolers and expanders of the first stage, second stage, third stage, fourth stage, fifth stage, and sixth stage, etc.

[0029] The hydrogen in the present invention is hydrogen at 76 - 90K and 0.5 Mpa - 20 Mpa. The hydrogen undergoes multi-stage ortho-para hydrogen conversion and cooling to lower the temperature. Under the state slightly lower than the boiling point of hydrogen, a trace amount of hydrogen isotopes is enriched into a constant component by using an isotope enrichment device with a cooling device.

[0030] Before each stage of hydrogen cooler, it passes through an ortho-para hydrogen converter. At the same time, the cooling capacity in the ortho-para hydrogen converter comes from low-temperature and high-pressure hydrogen with a regulating valve, which is used to control the refrigeration effect and enter the expander.

[0031] In this embodiment, the first-stage and second-stage ortho-para hydrogen converters, ortho-para hydrogen converter refrigeration regulating valves, expanders, and coolers are each integrated in a corresponding cryogenic box with high-vacuum insulation, which can minimize cold loss, radiation cold loss, and cooling loss to the greatest extent.

[0032] The three-stage isotope enricher 7, the three-stage isotope enrichment cooler 7-1, the isotope enrichment tank 8, the three-stage liquefaction cooler 9, the liquid hydrogen expansion valve 10, and the liquid hydrogen tank 11 are integrated in the corresponding cold box with high-vacuum insulation, which can minimize the loss of cold energy, radiant cold energy, and cooling loss.

[0033] Steps:

[0034] First-stage cooling: The low-temperature and high-pressure hydrogen at 76 - 90K is divided into two paths through the low-temperature and high-pressure hydrogen pipeline 1. One path is the main path for hydrogen liquefaction. It passes through the inlet pipeline 1-1 of the first-stage ortho-para hydrogen converter and enters the first-stage ortho-para hydrogen converter 2, where it is converted into the corresponding ortho-hydrogen and para-hydrogen equilibrium components at a temperature of 76 - 90K, releasing the conversion heat and then entering the first-stage liquefaction cooler 3.

[0035] The other path passes through the refrigeration regulating valve 1-2 of the first-stage ortho-para hydrogen converter and enters the inlet of the high-pressure expander 2-2. The refrigeration end of the first-stage ortho-para hydrogen converter 2 absorbs the heat released when hydrogen is converted into para-hydrogen, and then the low-temperature cooling medium hydrogen generated by isentropic expansion through the high-pressure expander inlet pipeline 2-1 enters the inlet of the high-pressure expander 2-2. After passing through the high-pressure expander outlet pipeline 2-3, it enters the first-stage liquefaction cooler 3, transfers heat to the hydrogen coming out of the first-stage ortho-para hydrogen converter 2, enters the refrigeration end of the first-stage ortho-para hydrogen converter 2, absorbs the heat released when hydrogen is converted into para-hydrogen, and then enters the circulation pipe network 12. After being pressurized and cooled again, it re-enters the low-temperature and high-pressure hydrogen pipeline 1.

[0036] Second-stage cooling: The hydrogen coming out of the first-stage liquefaction cooler 3 is again divided into two paths. One path is the main path for hydrogen liquefaction. It passes through the inlet pipeline 3-1 of the second-stage ortho-para hydrogen converter and enters the second-stage ortho-para hydrogen converter 4, where it is converted into the corresponding ortho-hydrogen and para-hydrogen equilibrium components at the corresponding temperature, releases the conversion heat and then enters the second-stage liquefaction cooler 5. The other path passes through the refrigeration regulating valve 3-2 of the second-stage ortho-para hydrogen converter, and then through the medium-pressure expander inlet pipeline 4-1 to the inlet of the medium-pressure expander 4-2. The low-temperature cooling medium hydrogen generated by isentropic expansion through the medium-pressure expander 4-2 enters the second-stage cooler 5 through the medium-pressure expander outlet pipeline 4-3, transfers heat to the hydrogen coming out of the second-stage ortho-para hydrogen converter 4, enters the refrigeration end of the second-stage ortho-para hydrogen converter 4, absorbs the heat released when hydrogen is converted into para-hydrogen, and then enters the circulation pipe network 12.

[0037] Three-stage cooling: The hydrogen gas coming out of the secondary liquefaction cooler 5 is divided into two paths again. One path is the main hydrogen liquefaction path. It passes through the inlet pipeline 5-1 of the three-stage ortho-para hydrogen converter and enters the three-stage ortho-para hydrogen converter 6. At the corresponding temperature, it is converted into the corresponding ortho-hydrogen and para-hydrogen equilibrium components and enters the three-stage isotope enricher 7, and receives the cooling capacity from the three-stage isotope enrichment cooler 7-1. After the hydrogen gas and its isotopes generate and grow droplets, the liquid enters the isotope enrichment tank 8 through the enriched isotope liquid hydrogen pipeline 7-3. The unliquefied gas enters the three-stage liquefaction cooler 9 through the depleted isotope hydrogen gas pipeline 7-2 to complete refrigeration again. The gas volatilized from the isotope enrichment tank 8 and the gas discharged from the liquid hydrogen tank 11 through the liquid hydrogen tank exhaust pipeline 11-1 release the cooling capacity in the three-stage isotope enrichment cooler 7-1 and then merge into the circulation pipe network 12;

[0038] The other path passes through the three-stage ortho-para hydrogen converter refrigeration regulating valve 5-2 and enters the low-pressure expander 6-2. The low-temperature cooling medium hydrogen generated by the isentropic expansion enters the three-stage liquefaction cooler 9 through the low-pressure expander outlet pipeline 6-3 to cool the depleted isotope hydrogen gas. After passing through the three-stage liquefaction cooler hydrogen gas outlet pipeline 9-1, it enters the refrigeration end of the three-stage ortho-para hydrogen converter 6 to absorb the heat released when hydrogen is converted into para-hydrogen and then merges into the circulation pipe network 12. The unliquefied gas in the three-stage isotope enricher 7 is liquefied by the three-stage liquefaction cooler 9, and after being cooled by the liquid hydrogen expansion valve 10, the liquid hydrogen is injected into the liquid hydrogen tank 11.

[0039] In the present invention, according to the different outlet pressures of the high-pressure expander 2-2, the medium-pressure expander 4-2, and the low-pressure expander 6-2, the pressure of the circulation pipe network 12 is different, and the pressures in the isotope enrichment tank 8 and the liquid hydrogen tank 11 are different. According to the different liquefaction temperatures of hydrogen isotopes, it is divided into two pressure level modes, namely the high-pressure mode and the low-pressure mode.

[0040] Example 1, high-pressure mode

[0041] The temperature of the high-pressure low-temperature hydrogen gas is 76-90K, and the pressure is 3.5-20Mpa. After exchanging heat with the low-pressure hydrogen gas with an outlet temperature of 36-50K from the high-pressure expander, the temperature of the main hydrogen liquefaction path is reduced to 56-69K; after exchanging heat with the hydrogen gas with an outlet temperature of 26-45K from the medium-pressure expander, it is reduced to 40-50K.

[0042] Liquefied hydrogen gas and isotope enrichment. At a pressure level of 1.7 - 3 Mpa, hydrogen gas with a temperature of 21 - 25 K at the outlet pipeline of the low-pressure expander exchanges heat with hydrogen gas from the three-stage isotope enrichment cooler and is cooled down to a temperature within 33 K. After being depressurized by the liquid hydrogen expansion valve, liquefied hydrogen gas is obtained. The hydrogen gas coming out of the liquid hydrogen tank has a temperature of 20 - 25 K and enters the three-stage isotope enrichment cooler to exchange heat with the hydrogen gas in the main hydrogen liquefaction path, with a temperature of 26 K - 38 K, forming isotope-enriched liquid droplets and obtaining isotope-enriched liquid.

[0043] Example 2, low-pressure membrane

[0044] The temperature of the low-temperature hydrogen gas is 76 - 90 K and the pressure is 0.5 - 3.5 Mpa. After exchanging heat with low-pressure hydrogen gas with an outlet temperature of 36 - 50 K from the high-pressure expander, the temperature of the main hydrogen liquefaction path is reduced to 56 - 69 K; after exchanging heat with hydrogen gas with an outlet temperature of 26 - 45 K from the medium-pressure expander, it is reduced to 40 - 50 K.

[0045] Liquefied hydrogen gas and isotope enrichment. At a pressure level of 0.1 - 1 Mpa, hydrogen gas with a temperature of 21 - 25 K at the outlet pipeline of the low-pressure expander exchanges heat with hydrogen gas from the three-stage isotope enrichment cooler and has a temperature of 20 - 22 K. After being depressurized by the liquid hydrogen expansion valve, liquefied hydrogen gas is obtained. The hydrogen gas coming out of the liquid hydrogen tank has a temperature of 19 - 22 K and enters the three-stage isotope enrichment cooler to exchange heat with the hydrogen gas in the main hydrogen liquefaction path, with a temperature of 21 K - 23 K, forming isotope-enriched liquid droplets and obtaining isotope-enriched liquid.

[0046] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A hydrogen and hydrogen isotope enrichment liquefaction system, characterized in that: include: Three-stage series cooling liquefaction unit and isotope enrichment system, including: The first-stage cooling unit comprises a first-stage normal-parahydrogen converter (2) and a first-stage liquefaction cooler (3), and the unit is equipped with a high-pressure expander (2-2); The secondary cooling unit comprises a secondary normal-parahydrogen converter (4) and a secondary liquefaction cooler (5), and is equipped with a medium-pressure expander (4-2); The three-stage cooling unit comprises a three-stage normal-parahydrogen converter (6) and a three-stage liquefaction cooler (9), and is equipped with a low-pressure expander (6-2); The circulation pipe network (12) connects the outlets of the expanders at each level with the inlet of the system; The isotope enrichment system comprises a three-stage isotope enricher (7), an isotope enrichment tank (8) and a liquid hydrogen tank (11) connected in series, and forms a closed loop through a liquid hydrogen expansion valve (10) and a three-stage liquefied cooler (9).

2. The hydrogen and hydrogen isotope enrichment liquefaction system according to claim 1, characterized in that: A para-hydrogen converter refrigeration regulating valve (1-2) is provided at the refrigeration end of the first-stage para-hydrogen converter (2), and its outlet is connected to the high-pressure expander (2-2) through a high-pressure expander inlet pipeline (2-1).

3. The hydrogen and hydrogen isotope enrichment liquefaction system according to claim 1, characterized in that: A secondary positron-parahydrogen converter refrigeration regulating valve (3-2) is provided at the refrigeration end of the secondary positron-parahydrogen converter (4), and its outlet is connected to the medium-pressure expander (4-2) through a medium-pressure expander inlet pipeline (4-1).

4. The hydrogen and hydrogen isotope enrichment liquefaction system according to claim 1, characterized in that: A three-stage para-hydrogen converter refrigeration regulating valve (5-2) is provided at the refrigeration end of the three-stage para-hydrogen converter (6), and its outlet is connected to the low-pressure expander (6-2) through a low-pressure expander inlet pipeline (6-1).

5. The hydrogen and hydrogen isotope enrichment liquefaction system according to claim 1, characterized in that: The primary cooling unit and the secondary cooling unit are respectively placed in a high vacuum insulation cold box.

6. The hydrogen and hydrogen isotope enrichment liquefaction system according to claim 1, characterized in that: The three-stage isotope enricher (7), the three-stage isotope enrichment cooler (7-1), the isotope enrichment tank (8), the three-stage liquefaction cooler (9), the liquid hydrogen expansion valve (10), and the liquid hydrogen tank (11) are integrated in a corresponding high vacuum insulation cold box.

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