A method and system for dry purification of hydrogen chloride

Abstract

The present invention relates to a dry purification method and system for hydrogen chloride, which comprises: 1) drying hydrogen chloride gas containing impurity gas to remove water vapor therein; 2) pressurizing the hydrogen chloride gas in step 1), cooling and condensing, so that the hydrogen chloride gas therein is liquefied to form high-purity hydrogen chloride liquid, and the impurity gas is kept in gaseous state, and the two are separated by gas and liquid; 3) the hydrogen chloride liquid is decompressed and gasified through a pressure reducing valve, and the hydrogen chloride gas is output; the present invention can also use low-temperature hydrogen chloride gas to cool and condense the pressurized impurity hydrogen chloride gas, and then output the purified hydrogen chloride gas, and use the principle of liquid hydrogen chloride gasification heat absorption to cool and condense the pressurized hydrogen chloride. The energy consumed by the method of the present invention is the electric energy used by the compressor and the refrigerant used by the second condenser, which reduces the cost compared with the steam used for wet purification; the present invention can also add a distillation tower to improve the purification purity of hydrogen chloride gas by gas lift.

Description

Technical Field

[0001] The invention relates to the field of hydrogen chloride production, and in particular to a hydrogen chloride dry purification system and method. Background Art

[0002] Hydrogen chloride gas synthesis is to obtain hydrogen chloride gas by fully burning chlorine and hydrogen in a synthesis furnace. During the combustion process, an excess of hydrogen must be charged, so the synthesized hydrogen chloride gas will contain about 6% hydrogen; in addition, the hydrogen chloride gas output by the synthesis furnace will also be mixed with water and other gas impurities. During the use of hydrogen chloride gas, if it is not purified, the use effect will deteriorate, the hydrogen chloride gas will be continuously consumed during use, and the mixed hydrogen will continue to accumulate. When the hydrogen accumulates to a certain amount, it will cause an explosion. Therefore, hydrogen chloride gas must be purified before use.

[0003] At present, the main method used for purifying hydrogen chloride gas is the analytical method, that is, hydrogen chloride gas is first introduced into a solution, and then the hydrogen chloride gas is analyzed out. The analytical equipment is a device for producing hydrogen chloride by concentration and analysis from hydrochloric acid disclosed in Chinese patent CN110606470A, which includes a hydrogen chloride analysis system and a calcium chloride concentration and evaporation system. The hydrogen chloride analysis system includes a jet mixer, an analysis tower, a hydrogen chloride primary condenser, a hydrogen chloride secondary condenser, a demister, a condensed acid tank, an analysis reboiler and an analysis condensation water tank; the calcium chloride concentration and evaporation system includes a first-effect evaporator, a first-effect flash tank, a first-effect condensation water tank, a second-effect evaporator, a second-effect flash tank, a second-effect condensation water tank, a third-effect evaporator, a third-effect flash tank, a third-effect condensation water tank, a third-effect discharge preheater, an evaporative condenser, a vacuum buffer tank and a water jet pump vacuum unit. The process of analysis is that the solution is dropped from the top of the analysis tower, and high-temperature hydrogen chloride and water vapor are introduced from the bottom of the analysis tower. The two realize heat exchange in the tower, so that the hydrogen chloride gas in the concentrated hydrochloric acid is analyzed and removed.

[0004] When high-purity hydrogen chloride gas is obtained by analytical method, a large amount of steam is needed to heat the solution. According to statistics, 1.5 tons of steam are needed to continuously purify 1 ton of hydrogen chloride gas. The current market price of steam is about 150 yuan / ton, and the cost of purifying hydrogen chloride gas is relatively high. Summary of the invention

[0005] The object of the present invention is to provide a hydrogen chloride production device and method to solve the problem of high cost required for the existing hydrogen chloride gas purification.

[0006] In order to achieve the purpose, the technical solution provided by the present invention is:

[0007] The present invention relates to a method for dry purification of hydrogen chloride, which comprises the following steps:

[0008] 1) Drying the hydrogen chloride gas containing impurities to remove water vapor therein;

[0009] 2) pressurizing the hydrogen chloride gas in step 1) to 0.4-1.0 MpaG, cooling and condensing, so that the hydrogen chloride gas therein is liquefied to form high-purity hydrogen chloride liquid, and the impurity gas remains in a gaseous state, and the gas and liquid are separated;

[0010] 3) The hydrogen chloride liquid is sent into the first condenser through the control valve, and the liquid hydrogen chloride is vaporized into gas for output.

[0011] Preferably, the step 3) is specifically as follows:

[0012] 3) The hydrogen chloride liquid is decompressed through the control valve and enters the shell side of the first condenser. The high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas under the combined effect of decompression and heat exchange with the hydrogen chloride gas containing impurities in the tube side of the first condenser. At the same time, the pressurized hydrogen chloride gas in step 1) is cooled and condensed by utilizing the principle of heat absorption during vaporization of the high-purity hydrogen chloride liquid, and then the hydrogen chloride gas is output.

[0013] Preferably, the dry purification method of hydrogen chloride comprises the following steps:

[0014] (1) The impure hydrogen chloride gas is dried by a drying device to remove water vapor therein;

[0015] (2) Entering the compressor and being compressed to 0.4-1.0MpaG, increasing the boiling point of the hydrogen chloride gas;

[0016] (3) The compressed impure hydrogen chloride gas is passed into the first condenser, and the impure hydrogen chloride gas in the first condenser is passed into the second condenser through the fourth gas outlet of the first condenser and the eighth gas inlet of the second condenser. The second condenser reduces the temperature of the impure hydrogen chloride gas through the refrigerant, so that the hydrogen chloride gas therein is liquefied to form high-purity hydrogen chloride liquid, and the impurity gas is discharged from the eighth gas outlet of the second condenser; the high-purity hydrogen chloride liquid is decompressed by the control valve and enters the shell side of the first condenser. Under the combined effect of decompression and heat exchange with the impurity hydrogen chloride gas passed from the compressor into the first condenser, the high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas;

[0017] (4) The high-purity hydrogen chloride liquid absorbs heat during the vaporization process, and the high-purity hydrogen chloride in the vaporization process is used as a refrigerant to cool the hydrogen chloride gas containing impurities in the first condenser, so that the high-pressure hydrogen chloride gas in the first condenser is liquefied to form high-purity hydrogen chloride liquid. The high-purity hydrogen chloride liquid then returns to the first condenser through a control valve for heat exchange, and part of the unliquefied gas in the hydrogen chloride gas containing impurities enters the second condenser in the form of gas to continue cooling and condensing;

[0018] (5) After returning to the first condenser, the vaporized hydrogen chloride is output from the first condenser in the form of gas.

[0019] Preferably, in the step (2), during the compression process, the temperature of the impurity-containing hydrogen chloride gas increases to generate heat, and the compressed impurity-containing hydrogen chloride gas is first partially passed into the first heat exchanger and partially passed into the second heat exchanger;

[0020] In the step (3), the compressed hydrogen chloride gas containing impurities in the first heat exchanger and the second heat exchanger is introduced into the first condenser;

[0021] The impurity gas output from the eighth gas outlet of the second condenser in the step (3) is returned to the second heat exchanger from the seventh gas inlet of the second heat exchanger, and is heat-exchanged with the compressed impurity-containing hydrogen chloride gas in the second heat exchanger to heat the impurity gas. After heating, the impurity gas is sent to the synthesis furnace from the seventh gas outlet of the second heat exchanger for reuse;

[0022] The high-purity hydrogen chloride gas output from the fifth gas outlet of the first condenser in the step (5) returns to the first heat exchanger from the third gas inlet of the first heat exchanger, exchanges heat with the impurity-containing hydrogen chloride gas compressed in the first heat exchanger, heats the high-purity hydrogen chloride gas to a temperature required for industrial use, and then outputs the high-purity hydrogen chloride gas from the third gas outlet of the first heat exchanger.

[0023] When hydrogen chloride gas is used in industry, it needs to be heated. When impurity gas enters the synthesis furnace for recycling, it also needs to be heated. Therefore, high-pressure hydrogen chloride gas containing impurities is used to heat the purified high-purity hydrogen chloride gas and the impurity gas respectively, which makes full use of the heat generated when the gas is pressurized, and reduces the energy consumption required for the subsequent use of hydrogen chloride gas and the recycling of impurity gas.

[0024] Preferably, the impure hydrogen chloride gas in the first heat exchanger and the second heat exchanger in the step (3) is first introduced into a distillation tower before being introduced into the first condenser; the liquefied hydrogen chloride in the steps (3) and (4) also passes through the distillation tower before entering the control valve for decompression, and the impurities dissolved in the hydrogen chloride liquid are stripped by the impure hydrogen chloride gas, so that the purity of the hydrogen chloride liquid is higher.

[0025] Preferably, in the step (2), part of the compressed impure hydrogen chloride gas is also introduced into a third heat exchanger. In the step (3), the refrigerant used for heat exchange with the second condenser is introduced into the third heat exchanger before being recovered, and heat exchange is performed with the impure hydrogen chloride gas in the third heat exchanger, so that part of the hydrogen chloride in the third heat exchanger is liquefied. The hydrogen chloride liquid, non-condensable hydrogen chloride gas and impurity gas all enter the distillation tower. The liquefied hydrogen chloride gas is output from the distillation tower liquid outlet of the distillation tower, and is decompressed by the control valve and enters the shell side of the first condenser for vaporization to form low-temperature hydrogen chloride gas. The non-condensable hydrogen chloride gas and impurity gas are output from the distillation tower outlet of the distillation tower, and enter the first condenser from the fourth air inlet of the first condenser, and continue to be liquefied according to the methods of steps (3) and (4).

[0026] Preferably, in the steps (3) and (4), before the hydrogen chloride liquid enters the control valve from the distillation tower for decompression, the hydrogen chloride liquid is heated by a reboiler to separate impurities dissolved in the hydrogen chloride liquid and return them to the distillation tower.

[0027] Preferably, the specific steps of drying the hydrogen chloride gas containing impurity gas in step 1) are:

[0028] (1.1) passing the hydrogen chloride gas containing impurities into a dry cooler to cool the hydrogen chloride gas containing impurities, so that part of the water vapor is liquefied due to the cooling and separated from the hydrogen chloride gas containing impurities;

[0029] (1.2) passing the hydrogen chloride gas containing impurities obtained in step (1.1) into a sulfuric acid drying tower, and using concentrated sulfuric acid in the sulfuric acid drying tower to absorb water vapor;

[0030] (1.3) The hydrogen chloride gas containing impurities obtained in step (1.2) is passed into a gas demister to remove sulfuric acid mist generated when the sulfuric acid drying tower absorbs water vapor.

[0031] The present invention also relates to a dry purification system for hydrogen chloride, which comprises a drying device, a compressor, a first heat exchanger, a first condenser, a second heat exchanger and a second condenser; the compressor is provided with a first air inlet and a first air outlet which are interconnected, and the first air inlet is connected to the drying device;

[0032] The first heat exchanger is provided with a second air inlet and a second air outlet which are interconnected, and a third air inlet and a third air outlet which are interconnected, and the second air inlet is connected to the first air outlet of the compressor;

[0033] The first condenser is provided with a fourth air inlet, a fourth air outlet and a first liquid outlet which are interconnected, and a fifth liquid inlet and a fifth air outlet which are interconnected, the fourth air inlet is connected to the second air outlet of the first heat exchanger, the first liquid outlet is connected to the fifth liquid inlet through a pipeline and a control valve arranged on the pipeline, and the fifth air outlet is connected to the third air inlet of the first heat exchanger;

[0034] The second heat exchanger is provided with a sixth air inlet and a sixth air outlet which are interconnected, and a seventh air inlet and a seventh air outlet which are interconnected, the sixth air inlet is connected to the first air outlet of the compressor, and the sixth air outlet is connected to the fourth air inlet of the first condenser;

[0035] The second condenser is provided with an eighth air inlet, an eighth air outlet and a second liquid outlet which are interconnected, as well as a refrigerant feed port and a refrigerant outlet for inputting and outputting external refrigerant, the eighth air inlet is connected to the fourth air outlet of the first condenser, the second liquid outlet is connected to the pipeline between the first liquid outlet and the control valve through a pipeline, and the eighth air outlet is connected to the seventh air inlet of the second heat exchanger;

[0036] The third gas outlet is used to output the purified hydrogen chloride gas, and the seventh gas outlet is used to output the treated impurity gas.

[0037] Preferably, the drying device comprises a drying cooler, a sulfuric acid drying tower and a gas demister connected in sequence. The drying cooler liquefies water vapor by cooling, the sulfuric acid drying tower absorbs water vapor by sulfuric acid, and sulfuric acid generates a large amount of heat and sulfuric acid mist after absorbing water vapor, and the gas demister is used to remove sulfuric acid mist.

[0038] Preferably, the bottom of the drying cooler is connected to a condensing acid tank, and the sulfuric acid drying tower is equipped with a cooler for cooling. After the water vapor is liquefied, part of the hydrogen chloride gas dissolves in water to form hydrochloric acid, and the condensing acid tank is used to collect this part of the hydrochloric acid; when the sulfuric acid drying tower absorbs water, a large amount of heat is generated, and the sulfuric acid drying tower is cooled by the cooler, which is beneficial to protect the sulfuric acid drying tower.

[0039] Preferably, a plurality of cooling condensers are provided between the gas demister and the sulfuric acid drying tower. The cooling condensers are used to cool the hydrogen chloride gas containing impurities to prevent the compressor temperature from being too high.

[0040] Preferably, it also includes a distillation tower, the distillation tower includes a distillation tower air inlet, a distillation tower air outlet, a distillation tower liquid inlet and a distillation tower liquid outlet, the second air outlet of the first heat exchanger and the sixth air outlet of the second heat exchanger are both connected to the distillation tower air inlet, the distillation tower air outlet is connected to the fourth air inlet of the first condenser, the first liquid outlet of the first condenser and the second liquid outlet of the second condenser are both connected to the distillation tower liquid inlet, and the distillation tower liquid outlet is connected to the fifth liquid inlet of the first condenser through a pipeline and a control valve arranged on the pipeline. The distillation tower extracts impurity gases dissolved in hydrogen chloride liquid by gas stripping, so that the purity of hydrogen chloride liquid is higher, and the purity of hydrogen chloride gas obtained after decompression and heat exchange is also higher.

[0041] Preferably, it also includes a third heat exchanger, which includes a first channel and a second channel, wherein both ends of the first channel are respectively connected to the compressor and the distillation tower, one end of the second channel is connected to the refrigerant discharge port of the second condenser, and the other end is used to recover the refrigerant.

[0042] Preferably, the distillation tower is further equipped with a reboiler, the bottom of which is connected to the liquid outlet of the distillation tower, and the top of which is connected to the interior of the distillation tower through a gas pipeline. The reboiler heats the hydrogen chloride liquid to a temperature between the boiling point of the impurities and the boiling point of hydrogen chloride based on the principle that the boiling point of hydrogen chloride is higher than that of the impurity gas, so that the impurity gas is vaporized and separated from the hydrogen chloride liquid, thereby making the hydrogen chloride liquid more pure.

[0043] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0044] 1. The dry purification system and method of hydrogen chloride of the present invention is to compress hydrogen chloride gas containing impurities by a compressor to increase the boiling point of the hydrogen chloride gas, then liquefy the hydrogen chloride by cooling the gas, and finally decompress the system by a control valve to vaporize the hydrogen chloride liquid due to the reduction of the boiling point to form high-purity hydrogen chloride gas. The energy consumed in the whole process is mainly the electric energy used by the compressor to compress the hydrogen chloride gas containing impurities and a small amount of refrigerant. The refrigerant comes from a refrigeration unit. It takes about 150 degrees of electricity to purify 1 ton of hydrogen chloride gas (the refrigerant has been converted into electricity). The cost of 150 degrees of electricity is 0.6 yuan, which is lower than the cost of steam used in the analytical method. Therefore, the invention can reduce the cost of hydrogen chloride purification.

[0045] 2. When the dry purification method for hydrogen chloride of the present invention is used to purify hydrogen chloride gas, the purified hydrogen chloride liquid absorbs heat during the decompression vaporization process, and the first condenser is cooled by the vaporized hydrogen chloride gas, and then the hydrogen chloride gas containing impurities in the first condenser is liquefied, thereby making full use of the cold capacity of the vaporized hydrogen chloride liquid and further reducing the amount of refrigerant used.

[0046] 3. In the process of purifying hydrogen chloride gas by the dry purification method of hydrogen chloride involved in the present invention, heat is generated when the hydrogen chloride gas containing impurities is compressed. The compressed hydrogen chloride gas containing impurities exchanges heat with the purified hydrogen chloride gas and the separated impurity gas, respectively, so that the purified hydrogen chloride gas reaches the industrial use temperature and the impurity gas reaches the temperature requirement for recycling, thereby reducing the energy consumption for subsequent heating of the purified hydrogen chloride gas and the separated impurity gas.

[0047] 4. The present invention uses the second condenser to cool the non-condensable hydrogen chloride gas output from the first condenser, thereby extracting hydrogen chloride as much as possible, increasing the hydrogen chloride extraction efficiency and reducing hydrogen chloride waste.

[0048] 5. The present invention utilizes hydrogen chloride gas to strip gaseous impurities in hydrogen chloride liquid in a distillation tower, utilizes a reboiler to vaporize gaseous impurities in hydrogen chloride liquid, thereby ensuring the purity of hydrogen chloride liquid, and then decompresses and vaporizes the high-purity hydrogen chloride liquid, thereby obtaining hydrogen chloride gas with higher purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a structural diagram of the dry purification system for hydrogen chloride involved in Example 1;

[0050] Figure 2 is a structural diagram of the dry purification system for hydrogen chloride involved in Example 2;

[0051] Figure 3 It is a schematic diagram of the structure of the compressor;

[0052] Figure 4 is a schematic structural diagram of a first heat exchanger;

[0053] Figure 5 is a schematic diagram of the structure of the first condenser;

[0054] Figure 6 is a schematic structural diagram of a second heat exchanger;

[0055] Figure 7 is a schematic diagram of the structure of the second condenser;

[0056] Figure 8 It is a schematic diagram of the structure of a distillation tower;

[0057] Fig. 9 It is a structural diagram of the dry purification system of hydrogen chloride involved in Example 3.

[0058] Icon Description: 1- Drying cooler, 11- Condensing acid tank, 2- Sulfuric acid drying tower, 21- Cooler, 3- Cooling condenser, 4- Gas demister, 5- Compressor, 51- First air outlet, 52- First air outlet, 6- First heat exchanger, 61- Second air inlet, 62- Second air outlet, 63- Third air inlet, 64- Third air outlet, 7- First condenser, 71- Fourth air inlet, 72- Fourth air outlet, 73- Fifth liquid inlet, 74- Fifth air outlet, 75- First liquid outlet , 8-second heat exchanger, 81-sixth air inlet, 82-sixth air outlet, 83-seventh air inlet, 84-seventh air outlet, 9-second condenser, 91-eighth air inlet, 92-eighth air outlet, 93-refrigerant feed port, 94-refrigerant outlet, 95-second liquid outlet, 10-distillation tower, 101-distillation tower air inlet, 102-distillation tower air outlet, 103-distillation tower liquid inlet, 104-distillation tower liquid outlet, 11-control valve, 12-reboiler, 13-third heat exchanger. DETAILED DESCRIPTION

[0059] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0060] Example 1

[0061] The hydrogen chloride gas in this embodiment is obtained by burning chlorine and hydrogen in a synthesis furnace. Since an excess of hydrogen needs to be introduced in the process of synthesizing hydrogen chloride gas, the impurity gas in the synthesized hydrogen chloride gas mainly refers to hydrogen, and the hydrogen content is about 6%. Of course, it also contains trace amounts of water vapor and other gases. This embodiment takes the removal of hydrogen and water vapor in the synthesized hydrogen chloride gas as an example to illustrate the present invention. It should be noted that when removing other impurity gases, it can also be achieved by only changing the temperature and pressure parameters.

[0062] See attached Figure 1 As shown, a hydrogen chloride dry purification system of this embodiment includes a drying device, a compressor 5, a first heat exchanger 6, a first condenser 7, a second heat exchanger 8 and a second condenser 9.

[0063] The drying device is used to remove trace water vapor in the synthetic hydrogen chloride gas, and includes a drying cooler 1, a sulfuric acid drying tower 2 and a gas demister 4 connected in sequence. The drying cooler 1 liquefies water vapor by cooling to form water droplets, and part of the hydrogen chloride gas will dissolve in water to form hydrochloric acid, so a condensed acid tank 11 is connected to the bottom of the drying cooler 1 for collecting this part of the hydrochloric acid; the sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid, and sulfuric acid generates a large amount of heat and sulfuric acid mist after absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is equipped with a cooler 21 for cooling, and the sulfuric acid drying tower 2 is cooled by the cooler 21, which is beneficial to protect the sulfuric acid drying tower 2, and the gas demister 4 can be used to remove sulfuric acid mist; the gas temperature output from the top of the sulfuric acid drying tower 2 reaches about 18 degrees. In order to protect the gas demister 4 and the compressor 5, a two-stage cooling condenser 3 is also provided between the sulfuric acid drying tower 2 and the gas demister 4 for cooling the hydrogen chloride gas containing impurities.

[0064] See attached Figure 1 and 3 As shown, the compressor 5 is provided with a first air inlet 51 and a first air outlet 52 which are interconnected. The first air inlet 51 is connected to a drying device. The hydrogen chloride gas containing impurity gas enters the compressor 5 from the first air inlet 51 after drying treatment. The compressor 5 compresses the gas to 0.9Mpa.

[0065] See attached Figure 1 and 4 As shown, the first heat exchanger 6 is provided with a second air inlet 61 and a second air outlet 62 which are interconnected, and a third air inlet 63 and a third air outlet 64 which are interconnected. The second air inlet 61 is connected to the first air outlet 52 of the compressor 5 .

[0066] See attached Figure 1 and 5 As shown, the first condenser 7 is provided with a fourth air inlet 71, a fourth air outlet 72 and a first liquid outlet 75 which are interconnected, and a fifth liquid inlet 73 and a fifth air outlet 74 which are interconnected. The fourth air inlet 71 is connected to the second air outlet 62 of the first heat exchanger 6, the first liquid outlet 75 is connected to the fifth liquid inlet 73 through a pipeline and a control valve 11 arranged on the pipeline, and the fifth air outlet 74 is connected to the third air inlet 63 of the first heat exchanger 6.

[0067] See attached Figure 1 and 6 As shown, the second heat exchanger 8 is provided with a sixth air inlet 81 and a sixth air outlet 82 which are interconnected, and a seventh air inlet 83 and a seventh air outlet 84 which are interconnected. The sixth air inlet 81 is connected to the first air outlet 52 of the compressor 5, and the sixth air outlet 82 is connected to the fourth air inlet 71 of the first condenser 7.

[0068] Refer to the attached Figure 1 and 7 As shown, the second condenser 9 is provided with an eighth air inlet 91, an eighth air outlet 92 and a second liquid outlet 95 which are interconnected, as well as a refrigerant feed port 93 and a refrigerant outlet 94 for inputting and outputting external refrigerant. The eighth air inlet 91 is connected to the fourth air outlet 72 of the first condenser 7, the second liquid outlet 95 is connected to the pipeline between the first liquid outlet 75 and the control valve 11 through a pipeline, and the eighth air outlet 92 is connected to the seventh air inlet 83 of the second heat exchanger 8.

[0069] Refer to the attached Figure 1 As shown, the third gas outlet 64 is used to output the purified hydrogen chloride gas, and the seventh gas outlet 84 is used to output the treated tail gas, namely hydrogen and a small amount of non-condensable hydrogen chloride gas.

[0070] The dry purification method of hydrogen chloride based on the above system comprises the following steps:

[0071] (1) The temperature of the impure hydrogen chloride gas after synthesis is 45-55° C. The impure hydrogen chloride gas is dried by passing through a drying cooler 1 and a sulfuric acid drying tower 2. The temperature of the impure hydrogen chloride gas after drying is 16° C. and the gas pressure is 0.052 MPaG. The specific steps of the drying process are as follows:

[0072] (1.1) The hydrogen chloride gas containing impurities is introduced into the dry cooler 1, and the dry cooler 1 cools part of the water vapor to liquefy due to the cooling, and separates it from the hydrogen chloride gas containing impurities, and the liquid water flows along the inner wall of the dry cooler 1 to the condensed acid tank 11;

[0073] (1.2) The hydrogen chloride gas containing impurities obtained in step (1.1) is passed into a sulfuric acid drying tower 2. The sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid. A large amount of heat and sulfuric acid mist are generated during the process of sulfuric acid absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is cooled by a cooler 21, and the dried gas is cooled by a two-stage cooling condenser;

[0074] (1.3) The hydrogen chloride gas containing impurities obtained in step (1.2) is passed into a gas demister 4 to remove sulfuric acid mist generated when the sulfuric acid drying tower 2 absorbs water vapor.

[0075] (2) The impure hydrogen chloride gas after drying by the drying device enters the compressor 5 for compression treatment, and the gas pressure of the impure hydrogen chloride gas is increased from 0.05-0.06Mpa to 0.9MpaG, thereby increasing the boiling point of the hydrogen chloride gas. At this time, the boiling point of the hydrogen chloride gas is increased from -85°C to about -33°C, while the boiling point of hydrogen is -259.2°C; during the compression of the impure hydrogen chloride gas, the temperature of the impure hydrogen chloride gas is increased to 42°C;

[0076] (3) The compressed impure hydrogen chloride gas is output from the first gas outlet 51, part of the impure hydrogen chloride gas is passed into the first heat exchanger 6 from the second gas inlet 61, and part of the impure hydrogen chloride gas is passed into the second heat exchanger 8 from the sixth gas inlet 81. The proportion of the impure hydrogen chloride gas passed into the first heat exchanger 6 and the second heat exchanger 8 is about 85%; the impure hydrogen chloride gas in the first heat exchanger 6 and the second heat exchanger 8 is output through the second gas outlet 62 and the sixth gas outlet 82, respectively, and enters the first condenser 7 from the fourth gas inlet 71. Since the first condenser 7 does not pass the refrigerant Therefore, all the impure hydrogen chloride gas in the first condenser 7 is output from the fourth gas outlet 72, and is passed into the second condenser 9 from the eighth gas inlet 91. The second condenser 9 inputs the refrigerant from the refrigeration unit from the refrigerant feed port 93, and the refrigerant temperature is -80°C. The refrigerant is recovered to the refrigeration unit from the refrigerant discharge port 94, and then the high-pressure impure hydrogen chloride gas in the second condenser 9 is cooled by the refrigerant, so that the hydrogen chloride gas therein is liquefied to form hydrogen chloride liquid, the temperature of the hydrogen chloride liquid is -57°C, and the pressure is 0.879MpaG, while the impurity gases such as hydrogen are still in the form of gas. The impurity gas exists in a state (a small amount of non-condensable hydrogen chloride gas is contained in the hydrogen gas), the temperature of the impurity gas is -40.8°C, and the pressure is 0.885MpaG. The impurity gas in the second condenser 9 is output from the eighth gas outlet 92 to the second heat exchanger 8, and heat is exchanged with the impurity-containing hydrogen chloride gas compressed in the second heat exchanger 8, and the impurity gas is heated and decompressed. After heating and decompression, it is sent to the synthesis furnace from the seventh gas outlet of the second heat exchanger 8 for reuse. The output impurity gas has a temperature of 25°C and a pressure of 0.878MpaG. At the same time, the impurity-containing chloride gas entering the second heat exchanger 8 from the compressor is heated and decompressed. The hydrogen gas is cooled, so that the temperature of the impure hydrogen chloride gas entering the first condenser from the second heat exchanger 8 is reduced to -33.95°C; the hydrogen chloride liquid in the second condenser 9 is output from the second liquid outlet 95, and after being reduced in pressure by the control valve 11, it returns to the shell side of the first condenser 7 from the fifth liquid inlet 73 of the first condenser 7. Under the combined effect of reduced pressure and heat exchange with the impure hydrogen chloride gas entering the first condenser 7 from the compressor, the high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas, and the temperature of the low-temperature hydrogen chloride gas is -33.99°C and the gas pressure is 0.89MpaG;

[0077] (4) The high-purity hydrogen chloride liquid absorbs heat during the vaporization process, and the high-purity hydrogen chloride in the vaporization process is used as a refrigerant to cool the high-pressure hydrogen chloride gas containing impurities in the first condenser 7, so that the hydrogen chloride gas is liquefied. The high-purity hydrogen chloride liquid is output from the first liquid outlet 75, and after being decompressed by the control valve 11, it returns to the first condenser 7 for heat exchange, and this process is repeated to continuously cool the first condenser 7; the part of the hydrogen chloride gas containing impurities that has not been liquefied enters the second condenser 9 to continue to cool and condense;

[0078] (5) The vaporized high-purity hydrogen chloride gas returned to the first condenser 7 from the fifth liquid inlet 73 is output from the fifth gas outlet 74, and then returned to the first heat exchanger 6 from the third gas inlet 63 of the first heat exchanger 6 to perform heat exchange with the compressed impurity-containing hydrogen chloride gas in the first heat exchanger 6, so as to heat the high-purity hydrogen chloride gas to a temperature required for industrial use, and then output the high-purity hydrogen chloride gas from the third gas outlet 64 of the first heat exchanger 6. At this time, the temperature of the high-purity hydrogen chloride gas is 48° C. and the gas pressure is 0.8789 MPaG.

[0079] The energy consumed in the entire purification process is mainly the electricity used by the compressor to compress the impure hydrogen chloride gas and a small amount of refrigerant. The refrigerant comes from the refrigeration unit, which also consumes electricity. According to statistics, it takes about 150 kWh of electricity to purify 1 ton of hydrogen chloride gas. The cost of 150 kWh of electricity is 90 yuan, which is lower than the cost of steam used in the analytical method. Therefore, this invention can reduce the cost of hydrogen chloride purification.

[0080] Example 2

[0081] The hydrogen chloride gas in this embodiment is obtained by burning chlorine and hydrogen in a synthesis furnace. Since an excess of hydrogen needs to be introduced in the process of synthesizing hydrogen chloride gas, the impurity gas in the synthesized hydrogen chloride gas mainly refers to hydrogen, and the hydrogen content is about 6%. Of course, it also contains trace amounts of water vapor and other gases. This embodiment takes the removal of hydrogen and water vapor in the synthesized hydrogen chloride gas as an example to illustrate the present invention. It should be noted that when removing other impurity gases, it can also be achieved by only changing the temperature and pressure parameters.

[0082] Refer to the attached Figure 2 As shown, the hydrogen chloride dry purification system includes a drying device, a compressor 5, a first heat exchanger 6, a first condenser 7, a second heat exchanger 8, a second condenser 9 and a distillation tower 10.

[0083] The drying device is used to remove trace water vapor in the synthetic hydrogen chloride gas, and includes a drying cooler 1, a sulfuric acid drying tower 2 and a gas demister 4 connected in sequence. The drying cooler 1 liquefies water vapor by cooling to form water droplets, and part of the hydrogen chloride gas will dissolve in water to form hydrochloric acid, so a condensed acid tank 11 is connected to the bottom of the drying cooler 1 for collecting this part of the hydrochloric acid; the sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid, and sulfuric acid generates a large amount of heat and sulfuric acid mist after absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is equipped with a cooler 21 for cooling, and the sulfuric acid drying tower 2 is cooled by the cooler 21, which is beneficial to protect the sulfuric acid drying tower 2, and the gas demister 4 can be used to remove sulfuric acid mist; the gas temperature output from the top of the sulfuric acid drying tower 2 reaches about 18 degrees. In order to protect the gas demister 4 and the compressor 5, a two-stage cooling condenser 3 is also provided between the sulfuric acid drying tower 2 and the gas demister 4 for cooling the hydrogen chloride gas containing impurities.

[0084] See attached Figure 2 and 3 As shown, the compressor 5 is provided with a first air inlet 51 and a first air outlet 52 which are interconnected. The first air inlet 51 is connected to a drying device. The hydrogen chloride gas containing impurity gas enters the compressor 5 from the first air inlet 51 after drying treatment. The compressor 5 compresses the gas to 0.9Mpa.

[0085] See attached Figure 2 and 4 As shown, the first heat exchanger 6 is provided with a second air inlet 61 and a second air outlet 62 which are interconnected, and a third air inlet 63 and a third air outlet 64 which are interconnected. The second air inlet 61 is connected to the first air outlet 52 of the compressor 5 .

[0086] See attached Figure 2 and 6 As shown, the second heat exchanger 8 is provided with a sixth air inlet 81 and a sixth air outlet 82 which are interconnected, and a seventh air inlet 83 and a seventh air outlet 84 which are interconnected. The sixth air inlet 81 is connected to the first air outlet 52 of the compressor 5 .

[0087] See attached Figure 2 and 8 As shown, the distillation tower 10 includes a distillation tower air inlet 101, a distillation tower air outlet 102, a distillation tower liquid inlet 103 and a distillation tower liquid outlet 104, the second air outlet 62 of the first heat exchanger 6 and the sixth air outlet 82 of the second heat exchanger 8 are both connected to the distillation tower air inlet 101, and the distillation tower air outlet 102 is connected to the fourth air inlet 71 of the first condenser 7.

[0088] See attached Figure 2 and 5As shown, the first condenser 7 is provided with a fourth air inlet 71, a fourth air outlet 72 and a first liquid outlet 75 which are interconnected, and a fifth liquid inlet 73 and a fifth air outlet 74 which are interconnected. The first liquid outlet 75 is connected to the liquid inlet 103 of the distillation tower through a liquid pipeline, and the fifth air outlet 74 is connected to the third air inlet 63 of the first heat exchanger 6.

[0089] Refer to the attached Figure 2 and 7 As shown, the second condenser 9 is provided with an eighth air inlet 91, an eighth air outlet 92 and a second liquid outlet 95 which are interconnected, as well as a refrigerant feed port 93 and a refrigerant outlet 94 for inputting and outputting external refrigerant. The eighth air inlet 91 is connected to the fourth air outlet 72 of the first condenser 7, the second liquid outlet 95 is connected to the liquid inlet 103 of the distillation tower through a liquid pipeline, and the eighth air outlet 92 is connected to the seventh air inlet 83 of the second heat exchanger 8.

[0090] Refer to the attached Figure 2 As shown, the liquid outlet 104 of the distillation tower is connected to the fifth liquid inlet 74 of the first condenser 7 through a pipeline and a control valve 11 arranged on the pipeline. The principle of the distillation tower 10 is to utilize the different volatilities of the components in the mixture, that is, the different vapor pressures of the components at the same temperature to transfer the light components in the liquid phase to the gas phase, and the heavy components in the gas phase to the liquid phase, thereby realizing the separation of the distillation tower. In this embodiment, the distillation tower 10 extracts the impurity gas dissolved in the hydrogen chloride liquid by gas stripping, that is, when the impurity hydrogen chloride gas entering from the distillation tower gas inlet 101 and the hydrogen chloride liquid entering from the distillation tower liquid inlet 103 are combined in the distillation tower 10, the hydrogen chloride gas in the gas phase is transferred to the hydrogen chloride liquid, and the hydrogen dissolved in the hydrogen chloride liquid in the liquid phase is transferred to the gas phase, so that the purity of the hydrogen chloride liquid is higher, and after the hydrogen chloride gas is obtained by decompression, the purity of the hydrogen chloride is also higher. The distillation tower 10 is further equipped with a reboiler 12, the bottom of which is connected to the distillation tower liquid outlet 104, and the top of which is connected to the interior of the distillation tower 10 through a gas pipeline. The reboiler 12 heats the hydrogen chloride liquid to a temperature between the boiling point of the impurities and the boiling point of hydrogen chloride based on the principle that the boiling point of hydrogen chloride is higher than that of the impurity gas, so that the impurity gas is vaporized and separated from the hydrogen chloride liquid, thereby making the hydrogen chloride liquid more pure.

[0091] The third gas outlet 64 is used to output the purified hydrogen chloride gas, and the seventh gas outlet 84 is used to output the treated tail gas, namely hydrogen and a small amount of non-condensable hydrogen chloride gas.

[0092] The dry purification method of hydrogen chloride based on the above system comprises the following steps:

[0093] (1) The temperature of the impure hydrogen chloride gas after synthesis is 45-55° C. The impure hydrogen chloride gas is dried by passing through a drying cooler 1 and a sulfuric acid drying tower 2. The temperature of the impure hydrogen chloride gas after drying is 16° C. and the gas pressure is 0.052 MPaG. The specific steps of the drying process are as follows:

[0094] (1.1) The hydrogen chloride gas containing impurities is introduced into the dry cooler 1, and the dry cooler 1 cools part of the water vapor to liquefy due to the cooling, and separates it from the hydrogen chloride gas containing impurities, and the liquid water flows along the inner wall of the dry cooler 1 to the condensed acid tank 11;

[0095] (1.2) The hydrogen chloride gas containing impurities obtained in step (1.1) is passed into a sulfuric acid drying tower 2. The sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid. A large amount of heat and sulfuric acid mist are generated during the process of sulfuric acid absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is cooled by a cooler 21, and the dried gas is cooled by a two-stage cooling condenser;

[0096] (1.3) The hydrogen chloride gas containing impurities obtained in step (1.2) is passed into a gas demister 4 to remove sulfuric acid mist generated when the sulfuric acid drying tower 2 absorbs water vapor.

[0097] (2) The impure hydrogen chloride gas after drying by the drying device enters the compressor 5 for compression treatment, and the gas pressure of the impure hydrogen chloride gas is increased from 0.05-0.06Mpa to 0.9MpaG, thereby increasing the boiling point of the hydrogen chloride gas. At this time, the boiling point of the hydrogen chloride gas is increased from -85°C to about -33°C, while the boiling point of hydrogen is -259.2°C; during the compression of the impure hydrogen chloride gas, the temperature of the impure hydrogen chloride gas is increased to 42°C;

[0098] (3) The compressed impure hydrogen chloride gas is discharged from the first gas outlet 51, part of the impure hydrogen chloride gas is passed into the first heat exchanger 6 from the second gas inlet 61, and part of the impure hydrogen chloride gas is passed into the second heat exchanger 8 from the sixth gas inlet 81. The proportion of the impure hydrogen chloride gas passed into the first heat exchanger 6 and the second heat exchanger 8 is 85%; the impure hydrogen chloride gas in the first heat exchanger 6 and the second heat exchanger 8 is discharged through the second gas outlet 62 and the sixth gas outlet 82 respectively, passed into the distillation tower 10 from the distillation tower gas inlet 101, and then discharged from the distillation tower gas outlet 102, and enters the first condenser 7 from the fourth gas inlet 71 of the first condenser 7. Since the first condenser 7 does not pass refrigerant, the impurity hydrogen chloride gas in the first condenser 7 is All the hydrogen chloride gas is output from the fourth gas outlet 72, and is passed into the second condenser 9 from the eighth gas inlet 91 of the second condenser 9. The second condenser 9 inputs the refrigerant from the refrigeration unit from the refrigerant feed port 93, and the refrigerant temperature is -80°C. The refrigerant is recovered to the refrigeration unit from the refrigerant discharge port 94, and then the high-pressure impurity hydrogen chloride gas in the second condenser 9 is cooled by the refrigerant, so that the hydrogen chloride gas therein is liquefied to form hydrogen chloride liquid. The temperature of the hydrogen chloride liquid is -57°C and the pressure is 0.879MpaG, while the impurity gases such as hydrogen still exist in the form of gas (the hydrogen contains a small amount of non-condensable hydrogen chloride gas). The temperature of the impurity gas is -40.8°C and the pressure is 0.885MpaG. The impurity gas is output from the eighth gas outlet 92, enters the second heat exchanger 8 from the seventh gas inlet 83 of the second heat exchanger 8, exchanges heat with the compressed impurity-containing hydrogen chloride gas in the second heat exchanger 8, and heats the impurity gas. The heated and decompressed impurity gas is sent to the synthesis furnace for reuse from the seventh gas outlet 84 of the second heat exchanger 8. The output impurity gas has a temperature of 25° C. and a gas pressure of 0.878 MPaG. At the same time, the impurity-containing hydrogen chloride gas entering the second heat exchanger 8 from the compressor is cooled, so that the temperature of the impurity-containing hydrogen chloride gas entering the first condenser from the second heat exchanger 8 is reduced to -33.95° C. The hydrogen chloride liquid in the second condenser 9 is output from the second liquid outlet 95, and enters the distillation tower from the liquid inlet 103. In the distillation tower 10, the hydrogen chloride liquid contacts with the hydrogen chloride gas containing impurities, the hydrogen chloride gas in the gas phase is transferred to the hydrogen chloride liquid, and the hydrogen dissolved in the hydrogen chloride liquid in the liquid phase is transferred to the gas phase. After the hydrogen chloride liquid is stripped, it is discharged from the liquid outlet 104 of the distillation tower, and the hydrogen chloride liquid is heated by the reboiler 12, and the hydrogen dissolved in the hydrogen chloride liquid is separated and returned to the distillation tower 10. The hydrogen chloride liquid is decompressed by the control valve 11 and returned to the shell side of the first condenser 7 from the fifth liquid inlet 73 of the first condenser 7. Under the combined effect of decompression and heat exchange with the hydrogen chloride gas containing impurities introduced from the compressor into the first condenser 7, the high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas, and the temperature of the low-temperature hydrogen chloride gas is -33.99℃, air pressure is 0.89MpaG;.

[0099] (4) The high-purity hydrogen chloride liquid absorbs heat during the vaporization process, and the high-purity hydrogen chloride in the vaporization process is used as a refrigerant to cool the high-pressure impurity-containing hydrogen chloride gas in the first condenser 7, so that the hydrogen chloride gas is liquefied. The high-purity hydrogen chloride liquid is output from the first liquid outlet 75, and also enters the distillation tower 10 from the distillation tower liquid inlet 103. The hydrogen chloride liquid is gasified by the impurity-containing hydrogen chloride gas (the principle is the same as step (3), and this step is not explained in detail), and the impurity gas dissolved in the hydrogen chloride liquid is further removed by the reboiler 12. The high-purity hydrogen chloride liquid is decompressed by the control valve 11 and returns to the first condenser 7 from the fifth liquid inlet 73 for heat exchange. This is repeated to continuously cool the first condenser 7; part of the unliquefied gas in the impurity-containing hydrogen chloride gas enters the second condenser 9 to continue cooling and condensing;

[0100] (5) The high-purity hydrogen chloride gas obtained by evaporating the high-purity hydrogen chloride used as a refrigerant returned to the first condenser 7 from the fifth liquid inlet 73 is output from the fifth gas outlet 74, and then returned to the first heat exchanger 6 from the third gas inlet 63 of the first heat exchanger 6, and heat exchanged with the compressed impurity hydrogen chloride gas in the first heat exchanger 6, and the high-purity hydrogen chloride gas was heated to reach the temperature required for industrial use, and then the high-purity hydrogen chloride gas was output from the third gas outlet 64 of the first heat exchanger 6. At this time, the temperature of the high-purity hydrogen chloride gas is 48° C. and the gas pressure is 0.8789 MpaG; at the same time, the low-temperature high-purity hydrogen chloride gas cools the high-pressure impurity hydrogen chloride gas in the first condenser 7, and the high-pressure impurity hydrogen chloride gas is cooled to -33.95° C., and the gas pressure of the impurity hydrogen chloride gas is 0.894 MpaG.

[0101] This embodiment is additionally provided with a distillation tower 10 and a reboiler 12 on the basis of Embodiment 1. Compared with Embodiment 1, this embodiment can not only reduce the cost of hydrogen chloride purification, but also help to improve the purity of hydrogen chloride.

[0102] Example 3

[0103] The hydrogen chloride gas in this embodiment is obtained by burning chlorine and hydrogen in a synthesis furnace. Since an excess of hydrogen needs to be introduced in the process of synthesizing hydrogen chloride gas, the impurity gas in the synthesized hydrogen chloride gas mainly refers to hydrogen, and the hydrogen content is about 6%. Of course, it also contains trace amounts of water vapor and other gases. This embodiment takes the removal of hydrogen and water vapor in the synthesized hydrogen chloride gas as an example to illustrate the present invention. It should be noted that when removing other impurity gases, it can also be achieved by only changing the temperature and pressure parameters.

[0104] Refer to the attached Fig. 9As shown, the dry purification system of hydrogen chloride involved in this embodiment includes a drying device, a compressor 5, a first heat exchanger 6, a first condenser 7, a second heat exchanger 8, a second condenser 9, a distillation tower 10 and a third heat exchanger 13.

[0105] The drying device is used to remove trace water vapor in the synthetic hydrogen chloride gas, and includes a drying cooler 1, a sulfuric acid drying tower 2 and a gas demister 4 connected in sequence. The drying cooler 1 liquefies water vapor by cooling to form water droplets, and part of the hydrogen chloride gas will dissolve in water to form hydrochloric acid, so a condensed acid tank 11 is connected to the bottom of the drying cooler 1 for collecting this part of the hydrochloric acid; the sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid, and sulfuric acid generates a large amount of heat and sulfuric acid mist after absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is equipped with a cooler 21 for cooling, and the sulfuric acid drying tower 2 is cooled by the cooler 21, which is beneficial to protect the sulfuric acid drying tower 2, and the gas demister 4 can be used to remove sulfuric acid mist; the gas temperature output from the top of the sulfuric acid drying tower 2 reaches about 18 degrees. In order to protect the gas demister 4 and the compressor 5, a two-stage cooling condenser 3 is also provided between the sulfuric acid drying tower 2 and the gas demister 4 for cooling the hydrogen chloride gas containing impurities.

[0106] See attached Figure 2 and 3 As shown, the compressor 5 is provided with a first air inlet 51 and a first air outlet 52 which are interconnected. The first air inlet 51 is connected to a drying device. The hydrogen chloride gas containing impurity gas enters the compressor 5 from the first air inlet 51 after drying treatment. The compressor 5 compresses the gas to 0.9Mpa.

[0107] See attached Figure 2 and 4 As shown, the first heat exchanger 6 is provided with a second air inlet 61 and a second air outlet 62 which are interconnected, and a third air inlet 63 and a third air outlet 64 which are interconnected. The second air inlet 61 is connected to the first air outlet 52 of the compressor 5 .

[0108] See attached Figure 2 and 6 As shown, the second heat exchanger 8 is provided with a sixth air inlet 81 and a sixth air outlet 82 which are interconnected, and a seventh air inlet 83 and a seventh air outlet 84 which are interconnected. The sixth air inlet 81 is connected to the first air outlet 52 of the compressor 5 .

[0109] See attached Figure 2 and 8As shown, the distillation tower 10 includes a distillation tower air inlet 101, a distillation tower air outlet 102, a distillation tower liquid inlet 103 and a distillation tower liquid outlet 104, the second air outlet 62 of the first heat exchanger 6 and the sixth air outlet 82 of the second heat exchanger 8 are both connected to the distillation tower air inlet 101, and the distillation tower air outlet 102 is connected to the fourth air inlet 71 of the first condenser 7.

[0110] The third heat exchanger 13 includes a first channel and a second channel. The two ends of the first channel are respectively connected to the compressor 5 and the distillation tower 10. One end of the second channel is connected to the refrigerant outlet 94 of the second condenser 9, and the other end is used to recover the refrigerant and is connected to the refrigeration unit.

[0111] See attached Figure 2 and 5 As shown, the first condenser 7 is provided with a fourth air inlet 71, a fourth air outlet 72 and a first liquid outlet 75 which are interconnected, and a fifth liquid inlet 73 and a fifth air outlet 74 which are interconnected. The first liquid outlet 75 is connected to the liquid inlet 103 of the distillation tower through a liquid pipeline, and the fifth air outlet 74 is connected to the third air inlet 63 of the first heat exchanger 6.

[0112] See attached Figure 2 and 7 As shown, the second condenser 9 is provided with an eighth air inlet 91, an eighth air outlet 92 and a second liquid outlet 95 which are interconnected, as well as a refrigerant feed port 93 and a refrigerant outlet 94 for inputting and outputting external refrigerant. The eighth air inlet 91 is connected to the fourth air outlet 72 of the first condenser 7, the second liquid outlet 95 is connected to the liquid inlet 103 of the distillation tower through a liquid pipeline, and the eighth air outlet 92 is connected to the seventh air inlet 83 of the second heat exchanger 8.

[0113] See attached Figure 2As shown, the liquid outlet 104 of the distillation tower is connected to the fifth liquid inlet 74 of the first condenser 7 through a pipeline and a control valve 11 arranged on the pipeline. The principle of the distillation tower 10 is to utilize the different volatilities of the components in the mixture, that is, the different vapor pressures of the components at the same temperature to transfer the light components in the liquid phase to the gas phase, and the heavy components in the gas phase to the liquid phase, thereby realizing the separation of the distillation tower. In this embodiment, the distillation tower 10 extracts the impurity gas dissolved in the hydrogen chloride liquid by gas stripping, that is, when the impurity hydrogen chloride gas entering from the distillation tower gas inlet 101 and the hydrogen chloride liquid entering from the distillation tower liquid inlet 103 are combined in the distillation tower 10, the hydrogen chloride gas in the gas phase is transferred to the hydrogen chloride liquid, and the hydrogen dissolved in the hydrogen chloride liquid in the liquid phase is transferred to the gas phase, so that the purity of the hydrogen chloride liquid is higher, and after the hydrogen chloride gas is obtained by decompression, the purity of the hydrogen chloride is also higher. The distillation tower 10 is further equipped with a reboiler 12, the bottom of which is connected to the distillation tower liquid outlet 104, and the top of which is connected to the interior of the distillation tower 10 through a gas pipeline. The reboiler 12 heats the hydrogen chloride liquid to a temperature between the boiling point of the impurities and the boiling point of hydrogen chloride based on the principle that the boiling point of hydrogen chloride is higher than that of the impurity gas, so that the impurity gas is vaporized and separated from the hydrogen chloride liquid, thereby making the hydrogen chloride liquid more pure.

[0114] The third gas outlet 64 is used to output the purified hydrogen chloride gas, and the seventh gas outlet 84 is used to output the treated tail gas, namely hydrogen and a small amount of non-condensable hydrogen chloride gas.

[0115] The dry purification method of hydrogen chloride based on the above system comprises the following steps:

[0116] (1) The temperature of the impure hydrogen chloride gas after synthesis is 45-55° C. The impure hydrogen chloride gas is dried by passing through a drying cooler 1 and a sulfuric acid drying tower 2. The temperature of the impure hydrogen chloride gas after drying is 16° C. and the gas pressure is 0.052 MPaG. The specific steps of the drying process are as follows:

[0117] (1.1) The hydrogen chloride gas containing impurities is introduced into the dry cooler 1, and the dry cooler 1 cools part of the water vapor to liquefy due to the cooling, and separates it from the hydrogen chloride gas containing impurities, and the liquid water flows along the inner wall of the dry cooler 1 to the condensed acid tank 11;

[0118] (1.2) The hydrogen chloride gas containing impurities obtained in step (1.1) is passed into a sulfuric acid drying tower 2. The sulfuric acid drying tower 2 absorbs water vapor through sulfuric acid. A large amount of heat and sulfuric acid mist are generated during the process of sulfuric acid absorbing water vapor. Therefore, the sulfuric acid drying tower 2 is cooled by a cooler 21, and the dried gas is cooled by a two-stage cooling condenser;

[0119] (1.3) The hydrogen chloride gas containing impurities obtained in step (1.2) is passed into a gas demister 4 to remove sulfuric acid mist generated when the sulfuric acid drying tower 2 absorbs water vapor.

[0120] (2) The impure hydrogen chloride gas after drying by the drying device enters the compressor 5 for compression treatment, and the gas pressure of the impure hydrogen chloride gas is increased from 0.05-0.06Mpa to 0.9MpaG, thereby increasing the boiling point of the hydrogen chloride gas. At this time, the boiling point of the hydrogen chloride gas is increased from -85°C to about -33°C, while the boiling point of hydrogen is -259.2°C; during the compression of the impure hydrogen chloride gas, the temperature of the impure hydrogen chloride gas rises to 42°C;

[0121] (3) The compressed impure hydrogen chloride gas is output from the first gas outlet 51, part of the impure hydrogen chloride gas is passed into the first heat exchanger 6 from the second gas inlet 61, part of the impure hydrogen chloride gas is passed into the second heat exchanger 8 from the sixth gas inlet 81, and part of the impure hydrogen chloride gas is passed into the third heat exchanger; the impure hydrogen chloride gas in the first heat exchanger 6, the second heat exchanger 8 and the third heat exchanger 13 are all passed into the distillation tower 10, the impure hydrogen chloride gas is output from the distillation tower gas outlet 102, and enters the first condenser 7 from the fourth gas inlet 71 of the first condenser 7. Since the first condenser 7 does not pass the refrigerant, Therefore, all the impure hydrogen chloride gas in the first condenser 7 is output from the fourth gas outlet 72, and is passed into the second condenser 9 from the eighth gas inlet 91 of the second condenser 9. The second condenser 9 inputs the refrigerant from the refrigeration unit from the refrigerant feed port 93, and the refrigerant temperature is -80°C. The refrigerant is output from the refrigerant discharge port 94, and the output refrigerant is then passed into the third heat exchanger 13 to exchange heat with the impure hydrogen chloride gas in the third heat exchanger 13, so that part of the hydrogen chloride gas subsequently passed into the third heat exchanger 13 is liquefied, and the liquefied hydrogen chloride liquid enters the distillation tower 10 and flows downward, and is output from the distillation tower liquid outlet 104, and the impurity gas The liquid and non-condensable hydrogen chloride gas are output from the distillation tower outlet 102 to the first condenser 7, and the refrigerant is recovered to the refrigeration unit; the refrigerant is then used to cool the high-pressure impure hydrogen chloride gas in the second condenser 9 and the third heat exchanger 13, so that the hydrogen chloride gas therein is liquefied to form hydrogen chloride liquid, the temperature of the hydrogen chloride liquid is -57°C, and the pressure is 0.879MpaG; the impurity gases such as hydrogen in the second condenser 9 still exist in the form of gas (the hydrogen contains a small amount of non-condensable hydrogen chloride gas), the temperature of the impurity gas is -40.8°C, and the pressure is 0.885MpaG, and the impurity gas in the second condenser 9 is 0.879MpaG. The impurity gas is output from the eighth gas outlet 92, enters the second heat exchanger 8 from the seventh gas inlet 83 of the second heat exchanger 8, exchanges heat with the impurity-containing hydrogen chloride gas compressed in the second heat exchanger 8, and heats the impurity gas. The impurity gas after heating and decompression is sent to the synthesis furnace for reuse from the seventh gas outlet 84 of the second heat exchanger 8. The output impurity gas has a temperature of 25°C and a gas pressure of 0.878 MPaG. At the same time, the impurity-containing hydrogen chloride gas entering the second heat exchanger 8 from the compressor is cooled, so that the temperature of the impurity-containing hydrogen chloride gas entering the first condenser from the second heat exchanger 8 is reduced to -33.95°C.The hydrogen chloride liquid in the second condenser 9 is output from the second liquid outlet 95, enters the distillation tower 10 from the distillation tower liquid inlet 103, and merges with the hydrogen chloride liquid output from the third heat exchanger 13. In the distillation tower 10, the hydrogen chloride liquid contacts with the hydrogen chloride gas containing impurities, the hydrogen chloride gas in the gas phase is transferred to the hydrogen chloride liquid, and the hydrogen dissolved in the hydrogen chloride liquid in the liquid phase is transferred to the gas phase. After gas stripping, the hydrogen chloride liquid is output from the distillation tower liquid outlet 104, and is subjected to the reboiler 12 for chlorination. The hydrogen liquid is heated, the hydrogen dissolved in the hydrogen chloride liquid is separated and returned to the distillation tower 10, the hydrogen chloride liquid is decompressed by the control valve 11 and returned to the shell side of the first condenser 7 from the fifth liquid inlet 73 of the first condenser 7, and under the combined effect of decompression and heat exchange with the impurity-containing hydrogen chloride gas introduced from the compressor into the first condenser 7, the high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas, the temperature of the low-temperature hydrogen chloride gas is -33.99°C, and the gas pressure is 0.89MpaG;.

[0122] (4) The high-purity hydrogen chloride liquid absorbs heat during the vaporization process, and the high-purity hydrogen chloride in the vaporization process is used as a refrigerant to cool the high-pressure impurity-containing hydrogen chloride gas in the first condenser 7, so that the hydrogen chloride gas is liquefied. The high-purity hydrogen chloride liquid is output from the first liquid outlet 75, and also enters the distillation tower 10 from the distillation tower liquid inlet 103. The hydrogen chloride liquid is gasified by the impurity-containing hydrogen chloride gas (the principle is the same as step (3), and this step is not explained in detail), and the impurity gas dissolved in the hydrogen chloride liquid is further removed by the reboiler 12. The high-purity hydrogen chloride liquid is decompressed by the control valve 11 and returns to the first condenser 7 from the fifth liquid inlet 73 for heat exchange. This is repeated to continuously cool the first condenser 7; part of the unliquefied gas in the impurity-containing hydrogen chloride gas enters the second condenser 9 to continue cooling and condensing;

[0123] (5) The high-purity hydrogen chloride gas obtained by evaporating the high-purity hydrogen chloride used as a refrigerant returned to the first condenser 7 from the fifth liquid inlet 73 is output from the fifth gas outlet 74, and then returned to the first heat exchanger 6 from the third gas inlet 63 of the first heat exchanger 6, and heat exchanged with the compressed impurity hydrogen chloride gas in the first heat exchanger 6, and the high-purity hydrogen chloride gas was heated to reach the temperature required for industrial use, and then the high-purity hydrogen chloride gas was output from the third gas outlet 64 of the first heat exchanger 6. At this time, the temperature of the high-purity hydrogen chloride gas is 48° C. and the gas pressure is 0.8789 MpaG; at the same time, the low-temperature high-purity hydrogen chloride gas cools the high-pressure impurity hydrogen chloride gas in the first condenser 7, and the high-pressure impurity hydrogen chloride gas is cooled to -33.95° C., and the gas pressure of the impurity hydrogen chloride gas is 0.894 MpaG.

[0124] The present invention is described in detail above in conjunction with the embodiments, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for dry purification of hydrogen chloride, characterized in that: It includes the following steps: (1) The impure hydrogen chloride gas is dried by a drying device to remove water vapor; (2) Entering the compressor and being compressed to 0.4-1.0MpaG to increase the boiling point of hydrogen chloride gas; (3) The compressed impure hydrogen chloride gas is passed into the first condenser, and the impure hydrogen chloride gas in the first condenser is passed into the second condenser through the fourth gas outlet of the first condenser and the eighth gas inlet of the second condenser. The second condenser reduces the temperature of the impure hydrogen chloride gas through the refrigerant, so that the hydrogen chloride gas therein is liquefied to form high-purity hydrogen chloride liquid, and the impurity gas is discharged from the eighth gas outlet of the second condenser; the high-purity hydrogen chloride liquid is decompressed through the control valve and enters the shell side of the first condenser. Under the combined effect of decompression and heat exchange with the impurity hydrogen chloride gas passed from the compressor into the first condenser, the high-purity hydrogen chloride liquid is vaporized to form low-temperature hydrogen chloride gas; (4) The high-purity hydrogen chloride liquid absorbs heat during the vaporization process. The high-purity hydrogen chloride in the vaporization process is used as a refrigerant to cool the hydrogen chloride gas containing impurities in the first condenser, so that the high-pressure hydrogen chloride gas in the first condenser is liquefied to form high-purity hydrogen chloride liquid. The high-purity hydrogen chloride liquid then returns to the first condenser through the control valve for heat exchange, and the part of the unliquefied gas in the hydrogen chloride gas containing impurities enters the second condenser in the form of gas to continue cooling and condensing; (5) After returning to the first condenser, the vaporized hydrogen chloride is output from the first condenser in the form of gas.

2. The dry purification method of hydrogen chloride according to claim 1, characterized in that: In the step (2), during the compression process, the temperature of the impurity-containing hydrogen chloride gas increases to generate heat, and the compressed impurity-containing hydrogen chloride gas is first partially passed into the first heat exchanger and partially passed into the second heat exchanger; In the step (3), the compressed hydrogen chloride gas containing impurities in the first heat exchanger and the second heat exchanger is introduced into the first condenser; The impurity gas output from the eighth gas outlet of the second condenser in the step (3) is returned to the second heat exchanger from the seventh gas inlet of the second heat exchanger, and is heat-exchanged with the compressed impurity-containing hydrogen chloride gas in the second heat exchanger to heat the impurity gas. After heating, the impurity gas is sent to the synthesis furnace from the seventh gas outlet of the second heat exchanger for reuse; The high-purity hydrogen chloride gas output from the fifth gas outlet of the first condenser in the step (5) returns to the first heat exchanger from the third gas inlet of the first heat exchanger, exchanges heat with the impurity-containing hydrogen chloride gas compressed in the first heat exchanger, heats the high-purity hydrogen chloride gas to a temperature required for industrial use, and then outputs the high-purity hydrogen chloride gas from the third gas outlet of the first heat exchanger.

3. The dry purification method of hydrogen chloride according to claim 2, characterized in that: In the step (3), the impure hydrogen chloride gas in the first heat exchanger and the second heat exchanger is first introduced into a distillation tower before being introduced into the first condenser; in the steps (3) and (4), the liquefied hydrogen chloride also passes through the distillation tower before entering the control valve for decompression, and the impurities dissolved in the hydrogen chloride liquid are stripped by the impure hydrogen chloride gas, so that the purity of the hydrogen chloride liquid is higher.

4. The dry purification method of hydrogen chloride according to claim 2, characterized in that: In the step (2), part of the compressed impurity-containing hydrogen chloride gas is also introduced into a third heat exchanger. In the step (3), the refrigerant used for heat exchange with the second condenser is introduced into the third heat exchanger before being recovered, and heat exchange is performed with the impurity-containing hydrogen chloride gas in the third heat exchanger, so that part of the hydrogen chloride in the third heat exchanger is liquefied. The hydrogen chloride liquid, non-condensable hydrogen chloride gas and impurity gas all enter the distillation tower. The liquefied hydrogen chloride gas is discharged from the distillation tower liquid outlet of the distillation tower, and is reduced in pressure by the control valve and enters the shell side of the first condenser for vaporization to form low-temperature hydrogen chloride gas. The non-condensable hydrogen chloride gas and impurity gas are discharged from the distillation tower outlet of the distillation tower, and enter the first condenser from the fourth air inlet of the first condenser, and continue to be liquefied according to the methods of steps (3) and (4).

5. The dry purification method of hydrogen chloride according to claim 3, characterized in that: In the above steps (3) and (4), before the hydrogen chloride liquid enters the control valve from the distillation tower for decompression, the hydrogen chloride liquid is heated by a reboiler to separate the impurities dissolved in the hydrogen chloride liquid and return them to the distillation tower.

6. The dry purification method of hydrogen chloride according to claim 1, characterized in that: The specific steps of drying the hydrogen chloride gas containing impurity gas in step 1) are: (1.1) Passing the hydrogen chloride gas containing impurities into a dry cooler to cool the hydrogen chloride gas containing impurities, so that part of the water vapor is liquefied due to the cooling and separated from the hydrogen chloride gas containing impurities; (1.2) passing the hydrogen chloride gas containing impurities obtained in step (1.1) into a sulfuric acid drying tower, and absorbing water vapor with concentrated sulfuric acid in the sulfuric acid drying tower; (1.3) The hydrogen chloride gas containing impurities obtained in step (1.2) is passed into a gas demister to remove sulfuric acid mist generated when the sulfuric acid drying tower absorbs water vapor.

7. A hydrogen chloride dry purification system, characterized in that: It includes a drying device, a compressor, a first heat exchanger, a first condenser, a second heat exchanger and a second condenser; the compressor is provided with a first air inlet and a first air outlet which are interconnected, and the first air inlet is connected to the drying device; The drying device comprises a drying cooler, a sulfuric acid drying tower and a gas defoamer which are connected in sequence, the bottom of the drying cooler is connected to a condensed acid tank, the sulfuric acid drying tower is equipped with a cooler for cooling, and a plurality of cooling condensers are also arranged between the gas defoamer and the sulfuric acid drying tower; The first heat exchanger is provided with a second air inlet and a second air outlet which are interconnected, and a third air inlet and a third air outlet which are interconnected, and the second air inlet is connected to the first air outlet of the compressor; The first condenser is provided with a fourth air inlet, a fourth air outlet and a first liquid outlet which are interconnected, and a fifth liquid inlet and a fifth air outlet which are interconnected, the fourth air inlet is connected to the second air outlet of the first heat exchanger, the first liquid outlet is connected to the fifth liquid inlet through a pipeline and a control valve arranged on the pipeline, and the fifth air outlet is connected to the third air inlet of the first heat exchanger; The second heat exchanger is provided with a sixth air inlet and a sixth air outlet which are interconnected, and a seventh air inlet and a seventh air outlet which are interconnected, the sixth air inlet is connected to the first air outlet of the compressor, and the sixth air outlet is connected to the fourth air inlet of the first condenser; The second condenser is provided with an eighth air inlet, an eighth air outlet and a second liquid outlet which are interconnected, as well as a refrigerant feed port and a refrigerant outlet for inputting and outputting external refrigerant, the eighth air inlet is connected to the fourth air outlet of the first condenser, the second liquid outlet is connected to the pipeline between the first liquid outlet and the control valve through a pipeline, and the eighth air outlet is connected to the seventh air inlet of the second heat exchanger; The third gas outlet is used to output the purified hydrogen chloride gas, and the seventh gas outlet is used to output the treated impurity gas.

8. The dry purification system for hydrogen chloride according to claim 7, characterized in that: It also includes a distillation tower, which includes a distillation tower air inlet, a distillation tower air outlet, a distillation tower liquid inlet and a distillation tower liquid outlet. The second air outlet of the first heat exchanger and the sixth air outlet of the second heat exchanger are both connected to the distillation tower air inlet, the distillation tower air outlet is connected to the fourth air inlet of the first condenser, the first liquid outlet of the first condenser and the second liquid outlet of the second condenser are both connected to the distillation tower liquid inlet, and the distillation tower liquid outlet is connected to the fifth liquid inlet of the first condenser through a pipeline and a control valve arranged on the pipeline.

9. The hydrogen chloride dry purification system according to claim 8, characterized in that: It also includes a third heat exchanger, which includes a first channel and a second channel. The two ends of the first channel are respectively connected to the compressor and the distillation tower, one end of the second channel is connected to the refrigerant discharge port of the second condenser, and the other end is used to recover the refrigerant.

10. The dry purification system for hydrogen chloride according to claim 8, characterized in that: The distillation tower is also equipped with a reboiler, the bottom of the reboiler is connected to the liquid outlet of the distillation tower, and the top of the reboiler is connected to the inside of the distillation tower through a gas pipeline.

Images