CN108795508A - A method of detaching coke-stove gas using nitrogen and helium swell refrigeration - Google Patents

Abstract

The invention relates to a method for separating coke oven gas by expansion and refrigeration of nitrogen and helium. The method comprises the following steps: 1) After compressing and precooling the coke oven gas, it is sent to a first-stage nitrogen circulation expansion refrigeration system, and further cooled 2) After the methane discharged from the bottom of the rectification tower is cooled and liquefied by the secondary helium circulation expansion refrigeration system, it is sent to the liquefied natural gas storage tank for storage, and the hydrogen discharged from the top of the rectification tower is sequentially processed for the second stage. After the first normal and secondary state conversion and the second normal and secondary state conversion, it is sent to the liquid hydrogen storage tank for storage; the first normal and secondary state conversion process is provided by the secondary helium cycle expansion refrigeration system, and the second normal and secondary state conversion process is provided by the A three-stage helium cycle expansion refrigeration system provides cooling capacity. Compared with the prior art, the present invention produces liquefied natural gas and liquid hydrogen from coke oven gas through nitrogen and helium expansion low-temperature cycle, improves the utilization efficiency and energy utilization rate of coke oven gas, and reduces coke oven gas emptying Phenomenon, less environmental pollution.

Description

A method for separating coke oven gas by expansion and refrigeration of nitrogen and helium

technical field

The invention belongs to the technical field of comprehensive utilization of coke oven gas in the coking/steel mill industry, and relates to a method for separating coke oven gas by expanding and cooling nitrogen and helium.

Background technique

my country's coke production ranks among the top in the world, with 233 million tons in 2006, 353 million tons in 2009, and 443 million tons in 2012. A large amount of coke oven gas will be produced while producing coke. If calculated according to the 430m ³ coke oven gas produced by producing 1 ton of coke, the annual coke oven gas production in China in 2012 reached 190.5 billion m ³ , of which about 70% of the coke oven gas was used For the self-use of enterprises, commercial use and urban residents' use, the remaining coke oven gas is basically not well utilized, and some are even directly burned and released into the atmosphere. At present, the industrial use of coke oven gas mainly includes: as city gas, power generation, hydrogen extraction, methanol production, etc., but the efficiency and energy utilization of these methods are low, and the benefits are not obvious. Therefore, the effective recovery and utilization of coke oven gas is of great significance to realize the recycling of resources and the sustainable development of economy in our country.

The recyclable products of coke oven gas are mainly methane and hydrogen. This recovery method has several advantages:

(1) Raw material cost advantage. Coke oven gas is a by-product of the coke production process, and its price is very low. Hydrogen mainly exists in the form of compounds in nature. The price of elemental hydrogen is about 1.26 yuan/m ³ , the price of natural gas wellhead used in natural gas liquefaction is about 0.9 yuan/m ³ , and the current wellhead price in the United States has reached 1.99 yuan/m ³ ; The production cost of coke oven gas is mainly energy consumption cost, so the produced liquid hydrogen (LH ₂ ) and liquefied natural gas (LNG) are also very competitive in price.

(2) Advantages in energy consumption. At present, the mainstream production method of hydrogen is electrolysis of water or water gas method, and its energy consumption is about 50kWh/kg, which is relatively high. However, coke oven gas contains a large amount of elemental hydrogen. Separating hydrogen from coke oven gas can greatly reduce hydrogen production. energy consumption of the process.

(3) Both methane and hydrogen are clean energy that will be vigorously developed in China's energy structure in the future, and have broad application prospects. As the main component of natural gas, methane has the characteristics of high combustion calorific value, less atmospheric emissions, and high energy utilization efficiency; hydrogen energy has the advantages of high calorific value and recyclability, and its clean and pollution-free characteristics conform to the concept of sustainable development.

The Chinese invention patent with the publication number CN106753628A discloses a method and device for co-producing methanol from coke oven gas to LNG. The coke oven gas is first pressurized by a compressor, and then undergoes TSA pretreatment and PSA debenzene removal to remove naphthalene, tar, NH ₃ , benzene and other heavy hydrocarbon compounds are sent to the hydrodesulfurization unit for desulfurization after being pressurized by the coke oven gas compressor, and then sent to the MDEA decarbonization unit for decarbonization, and then LNG cryogenic separation to obtain the product LNG. The process is too complicated, the cost is high, and the stability and reliability need to be further verified. Moreover, this technology mainly recovers LNG products, and does not effectively utilize the high content of H ₂ in coke oven gas.

The Chinese invention patent with the publication number CN107446635A discloses a new method for utilizing coke oven gas. The raw coal gas produced by the coke oven is mixed with methane in a certain proportion, and the resulting mixed gas is passed into the plasma pyrolysis reactor to produce acetylene-containing gas. , The mixed gas of hydrogen and carbon monoxide, the mixed gas is purified and enters the separation and concentration device to extract the acetylene product and tail gas; the tail gas enters the methanation reaction device after compression and preheating, and the reacted gas passes through the pressure swing adsorption separation device to obtain the product hydrogen And synthetic methane, a part of the obtained synthetic methane is mixed with raw coke oven gas and sent to the plasma cracking reactor, and the other part is output as a product. Although this process can obtain three products of hydrogen, synthetic natural gas and acetylene, the process is complicated and the energy consumption is relatively high.

The Chinese invention patent with the publication number CN107261748A discloses a system for producing natural gas from coke oven gas, which uses pressure swing adsorption to treat coke oven gas and extract natural gas from it, but it does not have a large amount of hydrogen contained in coke oven gas for recovery and treatment .

The Chinese invention patent with the publication number CN107512702A discloses a coke oven gas hydrogen production process, the product of which is dry hydrogen without recycling methane.

The Chinese invention patent with the publication number CN106315510A discloses a coke oven gas hydrogen production process. On the basis of the traditional coke oven gas hydrogen production process, the light hydrocarbon conversion and carbon monoxide medium temperature conversion process are introduced to make the coke oven gas in the raw material Light hydrocarbon components such as methane and ethane and carbon monoxide all participate in the hydrogen production reaction, which can reduce the consumption of raw material gas for hydrogen production. However, the process involves a chemical conversion process, the stability is difficult to guarantee, and the process is relatively complicated.

Contents of the invention

The object of the present invention is to provide a method for separating coke oven gas by expansion and refrigeration of nitrogen and helium in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A method for utilizing nitrogen and helium expansion refrigeration to separate coke oven gas, the method comprising the following steps:

1) After the coke oven gas is compressed and pre-cooled, it is sent to the first-stage nitrogen cycle expansion refrigeration system, and then sent to the rectification tower after further cooling;

2) After the methane discharged from the bottom of the rectification tower is cooled and liquefied by the secondary helium circulation expansion refrigeration system, it is sent to the storage tank of liquefied natural gas for storage. After the normal-secondary state is converted, it is sent to the liquid hydrogen storage tank for storage;

In step 2), the cooling capacity is provided by the second-stage helium cycle expansion refrigeration system for the first normal-argon conversion process, and the cooling capacity is provided by the third-stage helium cycle expansion refrigeration system for the second normal-parameter conversion process. The hydrogen in coke oven gas is a mixture of orthohydrogen and parahydrogen, and the lower the temperature, the higher the proportion of parahydrogen. On the one hand, the normal-to-secondary state conversion is slow, and the normal-to-secondary state conversion has not started when the normal liquefaction is completed; on the other hand, the process of normal to secondary state conversion is an exothermic process, and its heat release exceeds the latent heat of vaporization. Therefore, if the conversion of normal and secondary states is not promoted simultaneously during the liquefaction process, the obtained liquid hydrogen product will be slowly lost. Simultaneously, since the lower the temperature, the greater the energy consumption for providing the same refrigeration capacity, so the present invention first performs a normal-argon conversion at a higher temperature (usually close to the liquid nitrogen temperature), and then performs a second normal-argon conversion at the final liquid hydrogen temperature. transform.

Further, in step 1), the coke oven gas is composed of methane and hydrogen. Coke oven gas is pre-purified to contain only methane and hydrogen.

Further, after the coke oven gas is compressed and pre-cooled, the pressure is 2.5-3.5 MPa and the temperature is 30-40°C. Compression and pre-cooling are carried out in two-stage compression cooling equipment.

Furthermore, the coke oven gas is sent into the rectification tower after being further cooled to below -150°C.

Further, in step 2), the methane is cooled and liquefied by the secondary helium cycle expansion refrigeration system to obtain high-pressure natural gas, and the high-pressure natural gas is throttled down to 0.08-0.12MPa, and then sent to a liquefied natural gas storage tank for storage .

Further, in step 2), the first normal-parallel transformation process and the second normal-paraphase transformation process are both carried out in a catalytic converter.

Further, in step 2), after the first normal-argon conversion is completed, the hydrogen gas is cooled and liquefied by the three-stage helium cycle expansion refrigeration system, and then the second normal-argon conversion is performed.

Further, in step 2), after the hydrogen is cooled and liquefied by the three-stage helium cycle expansion refrigeration system, high-pressure hydrogen is obtained, and the high-pressure hydrogen is reduced to 0.08-0.12MPa by throttling, and then the second normal and secondary state conversion is carried out .

Further, in step 2), the refrigerant in the first-stage nitrogen cycle expansion refrigeration system is nitrogen, and the refrigerants in the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system are all helium gas. In the present invention, in order to produce the liquid hydrogen product, it is necessary to provide extremely low cooling capacity, helium is a kind of good low-temperature refrigerant, can obtain up to about 100K with it, down to the low temperature of mK level, so the low-temperature section of the present invention (two The first-stage helium cycle expansion refrigeration system and the three-stage helium cycle expansion refrigeration system) the refrigerant is helium. Considering that the cost of the refrigerant helium is relatively high, and its adiabatic index is greater than that of the traditional refrigerant nitrogen, resulting in an increase in unit compression work, nitrogen is selected as the refrigerant in the high-temperature section (first-stage nitrogen cycle expansion refrigeration system) of the present invention, which can save cost and reduce energy consumption.

Further, a helium compression precooling system is provided between the secondary helium cycle expansion refrigeration system and the third stage helium cycle expansion refrigeration system, and the helium compression precooling system is connected with the secondary helium cycle expansion refrigeration system, the third stage The grade helium cycle expansion refrigeration system is connected. The helium compression pre-cooling system compresses and pre-cools the helium after cyclic heating, and then re-sends it to the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system.

The invention relates to a low-temperature gas separation and liquefaction technology with a rectification module, which is used for liquefaction and gas separation of coke oven gas. By using nitrogen and helium as refrigerants, it provides cooling for the high-temperature section and the low-temperature section respectively. A three-stage cycle expansion refrigeration system was established, in which the low-temperature working medium of the first-stage expansion cycle was nitrogen, and the low-temperature working medium of the other two-stage expansion cycles was helium. The rectification tower in the system can realize the effective separation of methane and hydrogen in coke oven gas. After being compressed and pre-cooled, the coke oven gas is subjected to a nitrogen expansion low-temperature cycle, cooled to -160°C or lower, and then enters the rectification tower. From the top and bottom of the rectification tower, hydrogen and gas with a purity of more than 99.5% can be obtained respectively Methane products; the secondary helium expansion cryogenic cycle provides cold energy for the liquefaction of natural gas, the condenser in the rectification tower, and the primary normal-to-secondary state conversion in the process of hydrogen liquefaction; the third-stage helium expansion low temperature cycle provides cold energy for hydrogen liquefaction and its The second-order normal-to-paradox transformation provides cold energy. The whole system realizes good energy integration, all the expansion work is recycled by the compressor in the corresponding cycle expansion refrigeration system, and the energy transferred by the condenser and reboiler in the rectification column is integrated by the system. Compared with the existing coke oven gas utilization process, the present invention realizes obtaining two high-purity liquid products from the coke oven gas for the first time, which is a breakthrough in the process development of coke oven gas utilization.

Coke oven gas is a by-product in the coke production process, so the system proposed by the present invention has basically no energy consumption for producing raw gas, and directly separates and liquefies the two gases from the low-cost mixed gas at low temperature, thereby obtaining two High purity liquid product. However, in the traditional technology for producing liquefied natural gas and liquid hydrogen, since hydrogen mainly exists in the form of compounds in nature, there is currently no method for producing elemental hydrogen with low energy consumption, so compared with the present invention, the traditional process The energy consumption for producing the same product includes three parts: hydrogen production, hydrogen liquefaction, and natural gas liquefaction. The total energy consumption is much higher than the system proposed by the present invention for producing liquefied natural gas and liquid hydrogen from low-cost coke oven gas.

Compared with the prior art, the present invention has the following characteristics:

1) The present invention makes full use of the characteristics of coke oven gas rich in hydrogen and methane, and produces liquefied natural gas (LNG) and liquid hydrogen (LH ₂ ) from coke oven gas through nitrogen and helium expansion low-temperature circulation, which are widely used in the petrochemical industry The simulation calculation of AspenHYSYS software proves that the present invention can realize methane and hydrogen recovery rates as high as 97.92% and 99.68% respectively, which greatly improves the utilization efficiency and energy utilization rate of coke oven gas, reduces the emptying phenomenon of coke oven gas, and thus Effectively reduce environmental pollution;

2) The traditional coke oven gas treatment method is to obtain LNG products through purification, methanation, PSA (pressure swing adsorption), and pressurized refrigeration, but the present invention does not adopt the PSA method, but directly enters the low-temperature system, through The method of adding a low-temperature rectification tower can directly obtain high-purity liquid hydrogen and LNG products.

Description of drawings

Fig. 1 is a schematic diagram of the process flow of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

Example 1:

A process for producing liquefied natural gas (LNG) and liquid hydrogen (LH ₂ ) from coke oven gas by using nitrogen and helium expansion low-temperature cycle, the embodiment is shown in Fig. 1 . The gas expansion cycle refrigerants are pure nitrogen and helium, of which the low-temperature working medium of the first expansion cycle is nitrogen, and the low-temperature working medium of the other two expansion cycles is helium, and the three-stage expansion cycle refrigerant flow rate is 5000 kmol/h , 5000kmol/h, 5500kmol/h, the raw coke oven gas includes the following mole fraction components: 50% CH ₄ +50% H ₂ , the pressure of coke oven gas is 0.2MPa, the temperature is 35°C, and the flow rate is 1000kmol/h. The specific steps of using coke oven gas to produce liquefied natural gas and liquid hydrogen are as follows:

1) Introduce the purified coke oven gas COG-101 with _CH4 and _H2 mole fractions of 50% into two-stage compression cooling equipment (compressor C-101, water cooler WC-101, compressor C-102, water cooling Device WC-102), the coke oven gas is compressed to 3.0MPa, the temperature is lowered to 35°C, and the energy consumption of this process is 2692kW;

2) Introduce the coke oven gas compressed in step 1) into the first-stage nitrogen cycle expansion refrigeration system and cool down to -160°C. At this time, the gasification rate of the mixed gas is 0.5216, and the final compression pressure of the working medium in the first-stage nitrogen cycle expansion refrigeration system is is 1.03MPa, the energy consumption of this process is 8094kW;

3) The coke oven gas cooled in step 2) is introduced into the rectification tower T-100, and hydrogen and methane products with a purity of more than 99.5% are obtained from the top and bottom respectively, and the flow rates are 498.8 kmol/h and 501.2 kmol/h respectively. h, the temperature is -223°C and -97.92°C respectively, and the gasification rate is 0.999 and 0 respectively;

₄ ) CH4 separated by step 3) is introduced into the secondary helium cycle expansion refrigeration system to cool down and liquefy. The final compression pressure of the working medium in the secondary helium cycle expansion refrigeration system is 0.22MPa, and the energy consumption of this process is 2487.4kW;

5) Introduce the high-pressure natural gas liquefied in step 4) into the throttle valve VLV-701, and reduce the pressure to a storage pressure of 0.1 MPa;

6) The H separated by step ₃ ) is introduced into the catalytic converter CON-101 to carry out normal-to-parallel conversion. The cooling capacity required for this process is 88.26kW, which is provided by the secondary helium cycle expansion refrigeration system;

7) Introduce the H after the first normal-parallel state transformation through step ₆ ) into the three-stage helium cycle expansion refrigeration system to cool down and liquefy, the final compression pressure of the three-stage helium expansion low-temperature cycle working medium is 3.4MPa, and the energy consumption of this process is 37772.9kW;

8) Introduce the high-pressure hydrogen liquefied in step 7) into the throttle valve VLV-100, and reduce the pressure to a storage pressure of 0.1 MPa;

9) The _H2 liquefied by step 8) is introduced into the catalytic converter CON-102 for the second normal-paraphase conversion, and the cooling capacity required for this process is 48.64kW, which is provided by the three-stage helium cycle expansion refrigeration system;

The liquefied natural gas and liquid hydrogen products liquefied through steps 5) and 9) can be introduced into storage tanks for storage.

Wherein, the first-stage nitrogen cycle expansion refrigeration system, the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system in step 2), step 4), and step 7) are three independent cycle expansion refrigeration systems. The refrigerant is a closed cycle, and it is an expansion refrigeration system with a heat recovery cycle, in which the output work of the expander is recycled by the compressor of the low temperature cycle where it is located.

Through simulation and calculation, in the process of producing liquefied natural gas and liquid hydrogen by using coke oven gas, the recovery rates of methane and hydrogen are as high as 98.44% and 99.66% respectively, and the total energy consumption is 51046.3kW. Taking the two products, the energy consumption required to obtain the same output is about 70852.2kW (hydrogen production: 50kWh/kg, hydrogen liquefaction: 12.5-15kWh/kg, natural gas liquefaction: 0.7kWh/kg), and the energy consumption is reduced by 27.95%.

Example 2:

A process for producing liquefied natural gas (LNG) and liquid hydrogen (LH ₂ ) from coke oven gas by using nitrogen and helium expansion low-temperature cycle, the embodiment is shown in Fig. 1 . The gas expansion cycle refrigerants are pure nitrogen and helium, of which the low-temperature working medium of the first expansion cycle is nitrogen, and the low-temperature working medium of the other two expansion cycles is helium, and the three-stage expansion cycle refrigerant flow rate is 5000 kmol/h , 4800kmol/h, 4600kmol/h, the raw coke oven gas includes the following mole fraction components: 60% CH ₄ +40% H ₂ , the pressure of coke oven gas is 0.2MPa, the temperature is 35°C, and the flow rate is 1000kmol/h. The specific steps of using coke oven gas to produce liquefied natural gas and liquid hydrogen are as follows:

1) Introduce the purified coke oven gas COG-101 with _CH4 and _H2 mole fractions of 60% and 40% respectively into two-stage compression cooling equipment (compressor C-101, water cooler WC-101, compressor C-101 102. Water cooler WC-102), which compresses the coke oven gas to 3.0MPa and lowers the temperature to 35°C. The energy consumption of this process is 2676kW;

2) Introduce the coke oven gas compressed in step 1) into the first-stage nitrogen cycle expansion refrigeration system to cool down to -160°C. At this time, the gasification rate of the mixed gas is 0.4137, and the final compression pressure of the working medium in the first-stage nitrogen cycle expansion refrigeration system is is 1.20MPa, the energy consumption of this process is 8772kW;

3) The coke oven gas cooled in step 2) is introduced into the rectification tower T-100, and hydrogen and methane products with a purity of more than 99.5% are obtained from the top and bottom, respectively, and the flow rates are 398.1 kmol/h and 601.9 kmol/h respectively. h, the temperatures were -223°C and -98.17°C, and the gasification rates were 0.999 and 0;

4) The CH ₄ separated in step 3) is introduced into the secondary helium cycle expansion refrigeration system to cool down and liquefy. The final compression pressure of the working fluid in the secondary helium cycle expansion refrigeration system is 0.20MPa, and the energy consumption of this process is 2020.2kW;

5) Introduce the high-pressure natural gas liquefied in step 4) into the throttle valve VLV-701, and reduce the pressure to a storage pressure of 0.1MPa;

6) The H separated by step ₃ ) is introduced into the catalytic converter CON-101 to carry out normal-parallel conversion. The cooling capacity required for this process is 70.43kW, which is provided by the secondary helium cycle expansion refrigeration system;

7) Introduce the _H2 after the first normal-to-parallel transformation in step 6) into the three-stage helium cycle expansion refrigeration system to cool down and liquefy. The final compression pressure of the three-stage helium expansion low-temperature cycle working medium is 3.13MPa. The energy consumption of this process is 30186.8kW;

8) Introduce the high-pressure hydrogen liquefied in step 7) into the throttle valve VLV-100, and reduce the pressure to a storage pressure of 0.1 MPa;

9) The _H2 liquefied by step 8) is introduced into the catalytic converter CON-102 for the second normal-parallel conversion. The cooling capacity required for this process is 38.82kW, which is provided by the three-stage helium cycle expansion refrigeration system;

The liquefied natural gas and liquid hydrogen products liquefied through steps 5) and 9) can be introduced into storage tanks for storage.

Wherein, the first-stage nitrogen cycle expansion refrigeration system, the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system in step 2), step 4), and step 7) are three independent cycle expansion refrigeration systems. The refrigerant is a closed cycle, and it is an expansion refrigeration system with a heat recovery cycle, in which the output work of the expander is recycled by the compressor of the low temperature cycle where it is located.

According to the simulation calculation, in the process of producing liquefied natural gas and liquid hydrogen by using coke oven gas, the recovery rates of methane and hydrogen are as high as 98.37% and 99.43% respectively, and the total energy consumption is 43655kW. For the two products, the energy consumption required to obtain the same output is about 58744.6kW (hydrogen production: 50kWh/kg, hydrogen liquefaction: 12.5-15kWh/kg, natural gas liquefaction: 0.7kWh/kg), and the energy consumption is reduced by 25.69%.

Example 3:

A method for utilizing nitrogen and helium expansion refrigeration to separate coke oven gas, the method comprising the following steps:

1) After the coke oven gas is compressed and pre-cooled, it is sent to the first-stage nitrogen cycle expansion refrigeration system, and then sent to the rectification tower after further cooling;

2) After the methane discharged from the bottom of the rectification tower is cooled and liquefied by the secondary helium circulation expansion refrigeration system, it is sent to the storage tank of liquefied natural gas for storage. After the transformation of normal and secondary states, it is sent to the liquid hydrogen storage tank for storage. The first normal and secondary state conversion process is provided by the second-stage helium cycle expansion refrigeration system, and the second normal and secondary state conversion process is provided by the third-stage helium cycle expansion refrigeration system. The system provides cooling.

In step 1), the coke oven gas is composed of methane and hydrogen; after the coke oven gas is compressed and pre-cooled, the pressure is 2.5MPa and the temperature is 40°C; after the coke oven gas is further cooled to below -150°C, it is sent to rectification tower.

In step 2), methane is cooled and liquefied by the secondary helium cycle expansion refrigeration system to obtain high-pressure natural gas, which is throttled down to 0.12 MPa, and then sent to the liquefied natural gas storage tank for storage; the first normal and secondary state conversion process and the second normal and secondary state conversion process are carried out in the catalytic converter; the hydrogen after the first normal and secondary state conversion is cooled and liquefied by the three-stage helium cycle expansion refrigeration system, and then the second normal and secondary state conversion is carried out; the hydrogen is passed through the three After the first-stage helium cycle expansion refrigeration system cools down and liquefies, high-pressure hydrogen is obtained. After the high-pressure hydrogen is throttled down to 0.08MPa, it undergoes the second normal-second state conversion; the refrigerant in the first-stage nitrogen cycle expansion refrigeration system is nitrogen, and the second The refrigerant in the first-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system is helium; there is a helium compression pre-cooling system between the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system. The helium compression precooling system is respectively connected with the secondary helium cycle expansion refrigeration system and the tertiary helium cycle expansion refrigeration system.

Example 4:

A method for utilizing nitrogen and helium expansion refrigeration to separate coke oven gas, the method comprising the following steps:

1) After the coke oven gas is compressed and pre-cooled, it is sent to the first-stage nitrogen cycle expansion refrigeration system, and then sent to the rectification tower after further cooling;

2) After the methane discharged from the bottom of the rectification tower is cooled and liquefied by the secondary helium circulation expansion refrigeration system, it is sent to the storage tank of liquefied natural gas for storage. After the transformation of normal and secondary states, it is sent to the liquid hydrogen storage tank for storage. The first normal and secondary state conversion process is provided by the second-stage helium cycle expansion refrigeration system, and the second normal and secondary state conversion process is provided by the third-stage helium cycle expansion refrigeration system. The system provides cooling.

In step 1), the coke oven gas is composed of methane and hydrogen; after the coke oven gas is compressed and pre-cooled, the pressure is 3.5MPa and the temperature is 30°C; the coke oven gas is further cooled to -170°C, and sent to the rectification tower middle.

In step 2), methane is cooled and liquefied by the secondary helium cycle expansion refrigeration system to obtain high-pressure natural gas, which is throttled down to 0.12 MPa, and then sent to the liquefied natural gas storage tank for storage; the first normal and secondary state conversion process and the second normal and secondary state conversion process are carried out in the catalytic converter; the hydrogen after the first normal and secondary state conversion is cooled and liquefied by the three-stage helium cycle expansion refrigeration system, and then the second normal and secondary state conversion is carried out; the hydrogen is passed through the three After the first-stage helium cycle expansion refrigeration system cools down and liquefies, high-pressure hydrogen is obtained. After the high-pressure hydrogen is throttled down to 0.12MPa, it undergoes the second normal-second state conversion; the refrigerant in the first-stage nitrogen cycle expansion refrigeration system is nitrogen, and the second The refrigerant in the first-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system is helium; there is a helium compression pre-cooling system between the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system. The helium compression precooling system is respectively connected with the secondary helium cycle expansion refrigeration system and the tertiary helium cycle expansion refrigeration system.

Example 5:

A method for utilizing nitrogen and helium expansion refrigeration to separate coke oven gas, the method comprising the following steps:

1) After the coke oven gas is compressed and pre-cooled, it is sent to the first-stage nitrogen cycle expansion refrigeration system, and then sent to the rectification tower after further cooling;

2) After the methane discharged from the bottom of the rectification tower is cooled and liquefied by the secondary helium circulation expansion refrigeration system, it is sent to the storage tank of liquefied natural gas for storage. After the transformation of normal and secondary states, it is sent to the liquid hydrogen storage tank for storage. The first normal and secondary state conversion process is provided by the second-stage helium cycle expansion refrigeration system, and the second normal and secondary state conversion process is provided by the third-stage helium cycle expansion refrigeration system. The system provides cooling.

In step 1), the coke oven gas is composed of methane and hydrogen; after the coke oven gas is compressed and pre-cooled, the pressure is 3MPa and the temperature is 35°C; after the coke oven gas is further cooled to -160°C, it is sent to the rectification tower .

In step 2), methane is cooled and liquefied by the secondary helium cycle expansion refrigeration system to obtain high-pressure natural gas, which is throttled down to 0.1MPa, and then sent to the liquefied natural gas storage tank for storage; the first normal and secondary state conversion process and the second normal and secondary state conversion process are carried out in the catalytic converter; the hydrogen after the first normal and secondary state conversion is cooled and liquefied by the three-stage helium cycle expansion refrigeration system, and then the second normal and secondary state conversion is carried out; the hydrogen is passed through the three After the first-stage helium cycle expansion refrigeration system cools down and liquefies, high-pressure hydrogen is obtained. After the high-pressure hydrogen is throttled down to 0.1MPa, it undergoes the second normal-secondary state conversion; the refrigerant in the first-stage nitrogen cycle expansion refrigeration system is nitrogen, and the second The refrigerant in the first-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system is helium; there is a helium compression pre-cooling system between the second-stage helium cycle expansion refrigeration system and the third-stage helium cycle expansion refrigeration system. The helium compression precooling system is respectively connected with the secondary helium cycle expansion refrigeration system and the tertiary helium cycle expansion refrigeration system.

As shown in Figure 1 (in the figure, C is the compressor, CON is the catalytic converter, E is the expander, HEX is the heat exchanger, MIX is the mixer, T is the rectification tower, TEE is the separator, V is the gas liquid separator, VLV is a throttle valve, WC is a water cooler, Q means heat, W means work), the whole process flow is:

Coke oven gas COG-101 is compressed and water-cooled twice through compressor C-101, water cooler WC-101, compressor C-102, and water cooler WC-102 in sequence, and then cooled by a first-stage nitrogen cycle expansion refrigeration system, and then sent to into the rectification tower T-100; the methane discharged from the bottom of the rectification tower T-100 is in the heat exchanger HEX-104 and the helium in the secondary helium cycle expansion refrigeration system is heat-exchanged and cooled to liquefy, and then passes through the throttle valve VLV-701 enters the gas-liquid separator V-100 after throttling and reducing pressure to separate liquefied natural gas (LNG) and send it to the LNG storage tank for storage; the material discharged from the top of the rectification tower T-100 enters the gas-liquid separator After the hydrogen is separated from V-101, the hydrogen is sent to the catalytic converter CON-101 for normal-secondary conversion. At the same time, the secondary helium cycle expansion refrigeration system refrigerates the catalytic converter CON-101 to obtain high-pressure hydrogen. The helium in the heat exchanger HEX-105 and the three-stage helium cycle expansion refrigeration system is heat-exchanged, cooled and liquefied, and then enters the catalytic converter CON-102 for the second normalization after throttling and reducing pressure through the throttle valve VLV-100 At the same time, the three-stage helium cycle expansion refrigeration system refrigerates the catalytic converter CON-102, and the final liquid hydrogen product is sent to the liquid hydrogen storage tank for storage.

Among them, in the first-stage nitrogen cycle expansion refrigeration system, after the nitrogen is expanded and refrigerated twice in the expander E-201 and expander E-202, it is mixed with the coke oven in the heat exchanger HEX-102 and the heat exchanger HEX-101. The gas is subjected to two-stage heat exchange, the coke oven gas is refrigerated, and the nitrogen after heat exchange is compressed and water-cooled twice by compressor C-203, water cooler WC-201, compressor C-204, and water cooler WC-202. , circulate into the expander E-201 and expander E-202 for expansion refrigeration.

The pre-cooled helium in the helium compression pre-cooling system is divided into two streams in the separator TEE-301, and enters the two-stage helium cycle expansion refrigeration system and the three-stage helium cycle expansion refrigeration system respectively. In the two-stage helium cycle expansion refrigeration system, the helium gas passes through the heat exchanger HEX-501 and the heat exchanger HEX-502 in sequence, then enters the expander E-501 for expansion refrigeration, and then enters the catalytic converter CON-101 for refrigeration, and then enters the catalytic converter CON-101 for refrigeration. After passing through heat exchanger HEX-503, heat exchanger HEX-104, and heat exchanger HEX-501 in turn, it enters the mixer MIX-301, wherein the helium gas flows between the heat exchanger HEX-104 and the rectifying tower T-100 The methane discharged from the bottom is used for heat exchange and refrigeration. In the three-stage helium cycle expansion refrigeration system, the helium gas passes through the compressor C-401, the water cooler WC-401, and the heat exchanger HEX-401 in sequence, then enters the expander E-401 for expansion and refrigeration, and then enters the catalytic converter CON- 102 for refrigeration, and then enter the mixer MIX-301 through heat exchanger HEX-105 and heat exchanger HEX-401 in turn, in which helium is exchanged and refrigerated with high-pressure hydrogen in heat exchanger HEX-105. In the helium compression pre-cooling system, the helium entering the mixer MIX-301 passes through the water cooler WC-303, the compressor C-301, the water cooler WC-301, the compressor C-302, and the water cooler WC-302 for multiple After the secondary compression is water-cooled, it enters the separator TEE-301.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration, which is characterized in that this method includes following Step：

1) after coke-stove gas being compressed and is pre-chilled, it is sent into level-one nitrogen cycle expansion refrigeration system, essence is sent into after further cooling down It evaporates in tower；

2) by the methane of rectifier bottoms discharge liquefied natural gas is sent into after the cooling liquefaction of two level helium cycle expansion refrigeration system It stores in storage tank, after carrying out the first positive parastate conversion, the second positive parastate conversion successively by the hydrogen being discharged at the top of rectifying column, is sent into It is stored in liquid hydrogen storage tank；

In step 2), the described first positive parastate conversion process provides cold by two level helium cycle expansion refrigeration system, described Second positive parastate conversion process provides cold by three-level helium cycle expansion refrigeration system.

2. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 1), the coke-stove gas is made of methane and hydrogen.

3. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 1), after coke-stove gas compression and precooling, pressure 2.5-3.5MPa, temperature is 30-40 DEG C.

4. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 1), the coke-stove gas is sent into after being further cooled to -150 DEG C or less in rectifying column.

5. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 2), the methane obtains high-pressure natural gas after the cooling liquefaction of two level helium cycle expansion refrigeration system, the height Pressure natural gas is sent into LNG tank and is stored after throttling is depressurized to 0.08-0.12MPa.

6. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature Be, in step 2), the described first positive parastate conversion process and the second positive parastate conversion process in catalytic converter into Row.

7. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 2), has carried out the hydrogen after the first positive parastate conversion after the cooling liquefaction of three-level helium cycle expansion refrigeration system, Carry out the second positive parastate conversion.

8. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 7, feature It is, in step 2), the hydrogen obtains high pressure hydrogen, the height after the cooling liquefaction of three-level helium cycle expansion refrigeration system Pressure hydrogen carries out the second positive parastate conversion after throttling is depressurized to 0.08-0.12MPa.

9. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 1, feature It is, in step 2), the refrigerant in the level-one nitrogen cycle expansion refrigeration system is nitrogen, and the two level helium cycle is swollen Refrigerant in swollen refrigeration system and three-level helium cycle expansion refrigeration system is helium.

10. a kind of method detaching coke-stove gas using nitrogen and helium swell refrigeration according to claim 9, feature It is, helium compression precooling is equipped between the two level helium cycle expansion refrigeration system and three-level helium cycle expansion refrigeration system System, the helium compress chilldown system respectively with two level helium cycle expansion refrigeration system, three-level helium cycle expansion refrigeration system phase Connection.