Hydrogen recovery device and chlor-alkali production system

Abstract

The utility model relates to a hydrogen recovery device and a chlor-alkali production system, the hydrogen recovery device comprises an absorber, a hydraulic ejector and a first pressure detection element, the absorber is configured to be connected with a synthesis furnace and absorb hydrogen chloride gas in tail exhaust gas of the synthesis furnace; the hydraulic ejector is configured to input residual gas of the absorber into the separation tank, and the separation tank is configured to separate hydrogen and hydrogen chloride gas in the residual gas; the separation tank is communicated with a first hydrogen blow-down pipe through a first blow-down stop valve and is communicated with the hydrogen buffer tank through a first recovery stop valve; the first pressure detection element is configured to detect the outlet pressure of the hydraulic ejector, and the first emptying stop valve and the first recycling stop valve are configured to be opened or closed based on the comparison relation between the actual pressure value obtained by the first pressure detection element and the first preset pressure value and the second preset pressure value; the first preset pressure value is positive pressure, and the second preset pressure value is negative pressure.

Description

Technical Field

[0001] This disclosure relates to the field of chlor-alkali production technology, and in particular to a hydrogen recovery device and a chlor-alkali production system. Background Technology

[0002] Currently, in the chlor-alkali production process, hydrogen and chlorine produced in the electrolyzer are burned in a synthesis furnace at a ratio of 1.05-1.1:1 to synthesize hydrogen chloride. This excess hydrogen ratio necessitates the installation of a high-energy-consuming water electrolysis hydrogen production system, which operates at near full capacity year-round. Most of the hydrogen chloride produced in the synthesis furnace reacts with acetylene to produce resin, with excess hydrogen being recovered through a hydrogen recovery process. A small portion of the hydrogen chloride gas is used to produce hydrochloric acid, but the excess hydrogen in this latter portion is directly discharged, resulting in resource waste. Therefore, how to recover hydrogen and reduce the load on water-based hydrogen production is an urgent problem to be solved. Utility Model Content

[0003] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a hydrogen recovery device and a chlor-alkali production system.

[0004] According to a first aspect of this disclosure, a hydrogen recovery device is provided for recovering excess hydrogen in chlor-alkali production, the hydrogen recovery device comprising:

[0005] An absorber configured to be connected to a synthesis furnace to absorb hydrogen chloride gas in the tail gas of the synthesis furnace;

[0006] A water jet, configured to feed the residual gas from the absorber into a separation tank, the separation tank being configured to separate hydrogen and hydrogen chloride gas within the residual gas;

[0007] The separation tank is connected to the first hydrogen vent pipe through the first vent shut-off valve, and is also connected to the hydrogen buffer tank through the first recovery shut-off valve.

[0008] A first pressure sensing element is configured to detect the outlet pressure of the hydraulic jet, and a first vent shut-off valve and a first recovery shut-off valve are configured to be opened or closed based on a comparison between the actual pressure value obtained by the first pressure sensing element and a first preset pressure value and a second preset pressure value.

[0009] The first preset pressure value is positive pressure, and the second preset pressure value is negative pressure;

[0010] The hydrogen recovery device also includes a hydrogen scrubbing tower connected to the hydrogen buffer tank, and a conveying element that transports the gas separated from the separation tank to the hydrogen buffer tank and the hydrogen scrubbing tower.

[0011] In one embodiment of this disclosure, the first vent shut-off valve is configured to open when the actual pressure value obtained by the first pressure detection element is greater than a first preset pressure value, and to close when the actual pressure value obtained by the first pressure detection element is less than the first preset pressure value.

[0012] The first recovery shut-off valve is configured to close when the actual pressure value obtained by the first pressure detection element is greater than the first preset pressure value, and to open when the actual pressure value obtained by the first pressure detection element is less than the first preset pressure value.

[0013] In one embodiment of this disclosure, the first vent shut-off valve is further configured to open when the actual pressure value obtained by the first pressure detection element is less than a second preset pressure value;

[0014] The first recovery shut-off valve is also configured to close when the actual pressure value obtained by the first pressure sensing element is less than a second preset pressure value.

[0015] In one embodiment of this disclosure, the hydrogen recovery device further includes:

[0016] The second hydrogen vent pipe is connected to the hydrogen buffer tank via a second vent shut-off valve.

[0017] The hydrogen buffer tank is connected to the hydrogen scrubbing tower via a second recovery shut-off valve;

[0018] A hydrogen oxygen analyzer is installed between the hydrogen buffer tank and the second hydrogen vent pipe. The hydrogen oxygen analyzer is configured to detect the oxygen content of the exhaust gas from the hydrogen buffer tank. The second vent shut-off valve and the second recovery shut-off valve are configured to be opened or closed based on the comparison between the actual oxygen content obtained by the hydrogen oxygen analyzer and the preset oxygen content.

[0019] In one embodiment of this disclosure, the second vent shut-off valve is configured to open when the actual oxygen content obtained by the hydrogen-oxygen analyzer is greater than a preset oxygen content, and to close when the actual oxygen content obtained by the hydrogen-oxygen analyzer is less than the preset oxygen content.

[0020] The second recovery shut-off valve is configured to close when the actual oxygen content obtained by the hydrogen-oxygen analyzer is greater than the preset oxygen content, and to open when the actual oxygen content obtained by the hydrogen-oxygen analyzer is less than the preset oxygen content.

[0021] In one embodiment of this disclosure, the delivery element is disposed upstream of the hydrogen buffer tank;

[0022] The hydrogen recovery device further includes a second pressure detection element configured to detect the gas pressure of the hydrogen buffer tank.

[0023] The hydrogen buffer tank is also connected to the second hydrogen vent pipe via a first pressure regulating valve. The first pressure regulating valve is configured to be opened or closed based on a comparison between the gas pressure of the hydrogen buffer tank detected by the second pressure sensing element and a third preset pressure value.

[0024] In one embodiment of this disclosure, the delivery element is disposed downstream of the hydrogen buffer tank.

[0025] In one embodiment of this disclosure, the hydrogen recovery device further includes a return channel connecting the upstream and downstream of the conveying element, and a third pressure detection element for detecting the inlet pressure of the conveying element. The return channel is provided with a second pressure regulating valve, which is configured to be opened or closed based on a comparison between the inlet pressure of the conveying element detected by the third pressure detection element and a fourth preset pressure value.

[0026] In one embodiment of this disclosure, the hydrogen recovery device further includes a nitrogen filling pipe, which is connected to the first hydrogen venting pipe via a nitrogen filling valve and is configured to protect the hydrogen during the hydrogen venting process.

[0027] According to a second aspect of this disclosure, a chlor-alkali production system is provided, the chlor-alkali production system comprising the hydrogen recovery device described in any of the above embodiments, and further comprising:

[0028] A synthesis furnace configured to burn hydrogen and chlorine to synthesize hydrogen chloride;

[0029] A resin production apparatus connected to the synthesis furnace and configured to use most of the hydrogen chloride generated by the synthesis furnace for resin production;

[0030] A hydrochloric acid production apparatus, connected to the hydrogen recovery apparatus, and configured to use a small portion of hydrogen chloride gas for hydrochloric acid production.

[0031] One beneficial effect of the hydrogen recovery device disclosed herein is that, through the sequential connection of an absorber, a hydraulic ejector, a separation tank, a hydrogen buffer tank, and a hydrogen scrubbing tower, the device absorbs hydrogen chloride gas from the tail gas of the synthesis furnace, recovering high-purity hydrogen. A first pressure detection element is installed to detect the outlet pressure of the hydraulic ejector. The separation tank is connected to a first hydrogen vent pipe via a first vent shut-off valve and to the hydrogen buffer tank via a first recovery shut-off valve. When the actual pressure value obtained by the first pressure detection element does not meet the recovery standard compared to a first preset pressure value and a second preset pressure value, the first vent shut-off valve opens and the first recovery shut-off valve closes, venting the hydrogen. When the actual pressure value obtained by the first pressure detection element meets the recovery standard, the first vent shut-off valve closes and the first recovery shut-off valve opens, recovering and reusing the hydrogen. This configuration not only recovers excess hydrogen during chlor-alkali production but also ensures that the hydrogen pressure and purity meet the recovery standards, achieving the effect of safely recovering excess hydrogen and reducing the load on water-based hydrogen production. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the present disclosure and, together with their description, serve to explain the principles of the present disclosure.

[0033] Figure 1 This is a schematic diagram of the structure of a chlor-alkali production system provided in one embodiment of this disclosure;

[0034] Figure 2 This is a schematic diagram of the structure of a chlor-alkali production system provided in one embodiment of this disclosure.

[0035] Figure 1 and Figure 2 The one-to-one correspondence between the component names and the reference numerals in the figures is as follows:

[0036] 1-Absorber; 2-Hydraulic jet; 3-Separation tank; 4-First vent shut-off valve; 5-First recovery shut-off valve; 6-First hydrogen vent pipe; 7-Hydrogen buffer tank; 8-First pressure sensing element; 9-Hydrogen scrubbing tower; 10-Conveying element; 11-Second hydrogen vent pipe; 12-Second vent shut-off valve; 13-Second recovery shut-off valve; 14-Hydrogen oxygen analyzer; 15-Second pressure sensing element; 16-First pressure regulating valve; 17-Third pressure sensing element; 18-Second pressure regulating valve; 19-Nitrogen charging valve; 20-Synthesis furnace; 21-Resin production unit; 22-Hydrochloric acid production unit; 23-Flow regulating valve; 24-Flow meter. Detailed Implementation

[0037] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0038] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use.

[0039] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0040] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0042] In this article, terms such as "up," "down," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, rather than to define the absolute position of these related parts.

[0043] In this article, "first," "second," etc., are used only to distinguish one another, and not to indicate degree of importance, order, or prerequisite for each other.

[0044] In this document, terms such as “equal” and “same” are not strict mathematical and / or geometric limitations, but also include errors that are understandable to those skilled in the art and permissible in manufacturing or use.

[0045] Existing hydrogen recovery devices are typically used to recover excess hydrogen from resin production processes, neglecting excess hydrogen from hydrochloric acid production processes. Therefore, this disclosure provides a hydrogen recovery device and a chlor-alkali production system. For ease of understanding, please refer to the following... Figure 1 , Figure 2 The specific structure and working principle of the hydrogen recovery device and chlor-alkali production system disclosed herein will be described in detail with reference to the embodiments.

[0046] The hydrogen recovery device disclosed herein includes an absorber 1, a hydraulic ejector 2, and a first pressure detection element 8. The absorber 1 is configured to be connected to a synthesis furnace 20 to absorb hydrogen chloride gas from the exhaust gas of the synthesis furnace 20. The hydraulic ejector 2 is configured to input the remaining gas from the absorber 1 into a separation tank 3. The separation tank 3 is configured to separate hydrogen and hydrogen chloride gas within the remaining gas. The separation tank 3 is connected to a first hydrogen vent pipe 6 via a first vent shut-off valve 4 and to a hydrogen buffer tank 7 via a first recovery shut-off valve 5. The first pressure detection element 8 is... The first vent shut-off valve 4 and the first recovery shut-off valve 5 are configured to open or close based on the comparison between the actual pressure value obtained by the first pressure detection element 8 and the first preset pressure value and the second preset pressure value; the first preset pressure value is positive pressure and the second preset pressure value is negative pressure; the hydrogen recovery device also includes a hydrogen scrubbing tower 9 connected to the hydrogen buffer tank 7, and a conveying element 10 that conveys the gas separated in the separation tank 3 from the separation tank 3 to the hydrogen buffer tank 7 and the hydrogen scrubbing tower 9.

[0047] Specifically, refer to Figure 1 Absorber 1 is a falling film absorber. A circulating absorption water channel is provided at the top of absorber 1, where the circulating absorption water forms a uniform thin film inside. Synthesis furnace 20 is connected to the bottom of absorber 1, and the exhaust gas flows counter-currently to contact the liquid film. The exhaust gas mainly contains hydrogen chloride gas and excess hydrogen gas. Taking advantage of the fact that hydrogen gas is poorly soluble in water while hydrogen chloride gas is readily soluble in water, the hydrogen chloride in the exhaust gas is absorbed into the circulating water, thereby producing hydrochloric acid.

[0048] Absorber 1 can be configured with at least two stages to improve its absorption effect on hydrogen chloride gas. In this embodiment, absorber 1 has three stages. The first-stage absorber is connected to the synthesis furnace 20 and is also connected to the second-stage absorber via a gas supply channel. The second-stage absorber is also connected to the third-stage absorber via a gas supply channel, allowing the exhaust gas to flow from the first-stage absorber to the second-stage absorber and then to the third-stage absorber. The third-stage absorber is connected to the circulating water pipeline and is also connected to the second-stage absorber via a water supply channel. The second-stage absorber is also connected to the first-stage absorber via a water supply channel, allowing the circulating water to flow from the third-stage absorber to the second-stage absorber and then to the first-stage absorber. The exhaust gas and circulating water flow in opposite directions, ensuring sufficient absorption of hydrogen chloride gas in the exhaust gas.

[0049] The hydraulic ejector 2 generates negative pressure through a high-speed flowing working fluid, thereby drawing in and transporting another fluid, making it more suitable for complex media compared to a centrifugal pump. In this embodiment, the hydraulic ejector 2 is connected to the third-stage absorber and is mainly used to transport the remaining gas after absorption by the absorber 1.

[0050] After absorption by absorber 1, the remaining gas mainly contains hydrogen and a small amount of hydrogen chloride. Separator 3 is connected to hydraulic ejector 2, which is also configured to introduce alkaline washing liquid. The alkaline washing liquid is transported by hydraulic ejector 2 to separator 3 and discharged from separator 3, mainly used to clean the remaining gas and remove hydrogen chloride.

[0051] The separator 3 is also connected to the first hydrogen vent pipe 6 and the hydrogen buffer tank 7 respectively. A first vent shut-off valve 4 is installed between the separator 3 and the first hydrogen vent pipe 6, and a first recovery shut-off valve 5 is installed between the separator 3 and the hydrogen buffer tank 7. When the first vent shut-off valve 4 is open and the first recovery shut-off valve 5 is closed, the hydrogen is vented. Conversely, when the first vent shut-off valve 4 is closed and the first recovery shut-off valve 5 is open, the hydrogen is recovered.

[0052] The first pressure detection element 8 is used to detect the pressure at the outlet of the hydraulic ejector 2, and the first preset pressure value is positive pressure, and the second preset pressure value is negative pressure. When the actual pressure value obtained by the first pressure detection element 8 is compared with the first preset pressure value, the opening or closing of the first vent shut-off valve 4 and the first recovery shut-off valve 5 is controlled according to the comparison result to prevent excessive pressure during hydrogen recovery. When the actual pressure value obtained by the first pressure detection element 8 is compared with the second preset pressure value, the opening or closing of the first vent shut-off valve 4 and the first recovery shut-off valve 5 is controlled according to the comparison result to prevent air from being drawn in by the negative pressure of the hydraulic ejector 2, thus ensuring the purity of the recovered hydrogen.

[0053] The hydrogen buffer tank 7 is connected to the hydrogen scrubbing tower 9. The gas in the separation tank 3 is transported to the hydrogen buffer tank 7 through the conveying element 10, and then enters the hydrogen scrubbing tower 9 to further remove impurities. The hydrogen scrubbing tower 9 is connected to the hydrogen compressor, and the hydrogen is recovered by the hydrogen compressor to other processes in the chlor-alkali production.

[0054] The hydrogen recovery device disclosed herein is sequentially connected via an absorber 1, a hydraulic ejector 2, a separator 3, a hydrogen buffer tank 7, and a hydrogen scrubbing tower 9. It absorbs hydrogen chloride gas from the exhaust gas of the synthesis furnace 20, recovering high-purity hydrogen. A first pressure detection element 8 is installed to detect the outlet pressure of the hydraulic ejector 2. The separator 3 is connected to a first hydrogen vent pipe 6 via a first vent shut-off valve 4 and to the hydrogen buffer tank 7 via a first recovery shut-off valve 5. When the actual pressure value obtained by the first pressure detection element 8 does not meet the recovery standard compared to a first preset pressure value and a second preset pressure value, the first vent shut-off valve 4 opens and the first recovery shut-off valve 5 closes, venting the hydrogen. When the actual pressure value obtained by the first pressure detection element 8 meets the recovery standard compared to the first preset pressure value and the second preset pressure value, the first vent shut-off valve 4 closes and the first recovery shut-off valve 5 opens, recovering and reusing the hydrogen. This setup not only recovers excess hydrogen from the chlor-alkali production process but also ensures that the hydrogen pressure and purity meet recovery standards, achieving the effect of safely recovering excess hydrogen and reducing the load on water-based hydrogen production.

[0055] In one embodiment, the first vent shut-off valve 4 is configured to open when the actual pressure value obtained by the first pressure detection element 8 is greater than the first preset pressure value, and to close when the actual pressure value obtained by the first pressure detection element 8 is less than the first preset pressure value; the first recovery shut-off valve 5 is configured to close when the actual pressure value obtained by the first pressure detection element 8 is greater than the first preset pressure value, and to open when the actual pressure value obtained by the first pressure detection element 8 is less than the first preset pressure value.

[0056] Specifically, when the actual pressure value obtained by the first pressure detection element 8 is greater than 2 kPa, the hydrogen pressure is too high, which will cause hydrogen embrittlement. That is, hydrogen under high pressure can easily penetrate into metal materials, causing the materials to become brittle and reducing their strength and toughness. This may lead to pipe or valve rupture. Hydrogen is a flammable and explosive gas. After hydrogen leaks, it spreads rapidly and mixes with air to form an explosive gas. It will explode when it comes into contact with a spark or high temperature. Therefore, the first vent shut-off valve 4 is opened and the first recovery shut-off valve 5 is closed to vent the hydrogen and reduce the pressure. When the actual pressure value obtained by the first pressure detection element 8 is less than 2 kPa, the first vent shut-off valve 4 is closed and the first recovery shut-off valve 5 is opened to recover the hydrogen.

[0057] In another embodiment, when the actual pressure value obtained by the first pressure detection element 8 is greater than 1.8 kPa, the first vent shut-off valve 4 opens and the first recovery shut-off valve 5 closes, venting the hydrogen and reducing the pressure; when the actual pressure value obtained by the first pressure detection element 8 is less than 1.8 kPa, the first vent shut-off valve 4 closes and the first recovery shut-off valve 5 opens, recovering the hydrogen. Furthermore, the first preset pressure value can be set to any pressure value between 1.8 and 2 kPa. Based on the comparison between the outlet pressure of the hydraulic ejector 2 and the first preset pressure value, the first vent shut-off valve 4 and the first recovery shut-off valve 5 control the venting of high-pressure hydrogen, achieving safe hydrogen recovery.

[0058] In one embodiment, the first vent shut-off valve 4 is further configured to open when the actual pressure value obtained by the first pressure sensing element 8 is less than the second preset pressure value; the first recovery shut-off valve 5 is further configured to close when the actual pressure value obtained by the first pressure sensing element 8 is less than the second preset pressure value.

[0059] Specifically, when the actual pressure value obtained by the first pressure detection element 8 is less than -1 kPa, the outlet of the hydraulic ejector 2 is under negative pressure. At this time, if the first vent shut-off valve 4 and the first recovery shut-off valve 5 are both open, air will be drawn into the hydrogen recovery device, resulting in impure hydrogen. If the first vent shut-off valve 4 is closed and the first recovery shut-off valve 5 is open, hydrogen cannot be recovered. Therefore, the first vent shut-off valve 4 is open and the first recovery shut-off valve 5 is closed, connecting the outlet of the hydraulic ejector 2 to the outside, and the pressure rises to a level suitable for normal recovery. The second preset pressure value is -0.5 to -1 kPa. Based on the comparison between the outlet pressure of the hydraulic ejector 2 and the second preset pressure value, the first vent shut-off valve 4 and the first recovery shut-off valve 5 control the connection between the outlet of the hydraulic ejector 2 and the outside, preventing air from being drawn in due to the negative pressure at the outlet of the hydraulic ejector 2, thus ensuring the purity of the recovered hydrogen.

[0060] In one embodiment, the hydrogen recovery device further includes a second hydrogen vent pipe 11, which is connected to a hydrogen buffer tank 7 via a second vent shut-off valve 12; the hydrogen buffer tank 7 is connected to a hydrogen scrubbing tower 9 via a second recovery shut-off valve 13; a hydrogen oxygen analyzer 14 is installed between the hydrogen buffer tank 7 and the second hydrogen vent pipe 11, which is configured to detect the oxygen content of the exhaust gas from the hydrogen buffer tank 7; the second vent shut-off valve 12 and the second recovery shut-off valve 13 are configured to be opened or closed based on the comparison between the actual oxygen content obtained by the hydrogen oxygen analyzer 14 and the preset oxygen content.

[0061] Specifically, the hydrogen-oxygen analyzer 14 is used to detect the oxygen content of the exhaust gas from the hydrogen buffer tank 7. When the comparison between the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 and the preset oxygen content does not meet the recovery standard, the second vent shut-off valve 12 opens and the second recovery shut-off valve 13 closes, venting the hydrogen. When the comparison between the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 and the preset oxygen content meets the recovery standard, the second vent shut-off valve 12 closes and the second recovery shut-off valve 13 opens, recovering the hydrogen. With this configuration, based on the comparison between the actual oxygen content of the gas discharged from the hydrogen buffer tank 7 and the preset oxygen content, the second vent shut-off valve 12 and the second recovery shut-off valve 13 control the venting of hydrogen with excessively high oxygen content, ensuring that the recovered hydrogen has high purity.

[0062] In one embodiment, the second vent shut-off valve 12 is configured to open when the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 is greater than a preset oxygen content, and to close when the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 is less than a preset oxygen content; the second recovery shut-off valve 13 is configured to close when the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 is greater than a preset oxygen content, and to open when the actual oxygen content obtained by the hydrogen-oxygen analyzer 14 is less than a preset oxygen content.

[0063] Specifically, the preset oxygen content is set to 0.5%. When the actual pressure value obtained by the hydrogen oxygen analyzer 14 is greater than 0.5%, the oxygen content in the hydrogen is high, indicating impurity. The second vent shut-off valve 12 opens, and the second recovery shut-off valve 13 closes, releasing the hydrogen. When the actual pressure value obtained by the hydrogen oxygen analyzer 14 is less than 0.5%, the hydrogen purity is high. The second vent shut-off valve 12 closes, and the second recovery shut-off valve 13 opens, recovering the hydrogen. This setting, based on the comparison between the actual oxygen content of the gas discharged from the hydrogen buffer tank 7 and the preset oxygen content, controls the venting of hydrogen with excessively high oxygen content by the second vent shut-off valve 12 and the second recovery shut-off valve 13, ensuring that the recovered hydrogen has high purity.

[0064] In one embodiment, the conveying element 10 is disposed upstream of the hydrogen buffer tank 7; the hydrogen recovery device further includes a second pressure detection element 15, which is configured to detect the gas pressure of the hydrogen buffer tank 7; the hydrogen buffer tank 7 is also connected to a second hydrogen vent pipe 11 via a first pressure regulating valve 16, which is configured to be opened or closed based on a comparison between the gas pressure of the hydrogen buffer tank 7 detected by the second pressure detection element 15 and a third preset pressure value.

[0065] Specifically, the conveying element 10 can be a compressor, which conveys the gas in the separator 3 to the hydrogen buffer tank 7. The third preset pressure value is set to 95-105 kPa. Taking 100 kPa as an example, when the second pressure detection element 15 detects that the gas pressure in the hydrogen buffer tank 7 is greater than 100 kPa, the first pressure regulating valve 16 opens, and the gas in the hydrogen buffer tank 7 is vented through the second hydrogen vent pipe 11, reducing the gas pressure in the hydrogen buffer tank 7. When the second pressure detection element 15 detects that the gas pressure in the hydrogen buffer tank 7 is less than 100 kPa, the first pressure regulating valve 16 closes. With this setting, hydrogen is first conveyed to the hydrogen buffer tank 7 through the conveying element 10 and then output. Stable hydrogen recovery is achieved by controlling the pressure in the hydrogen buffer tank 7.

[0066] In addition, a flow regulating valve 23 and a flow meter 24 are installed between the hydrogen buffer tank 7 and the hydrogen scrubbing tower 9 to control the flow rate of hydrogen recovery. When a fixed amount of hydrogen needs to be output, the flow regulating valve 23 opens and the second vent shut-off valve 12 closes, allowing hydrogen to be output until the preset flow rate value is reached. When the flow meter 24 detects that the output hydrogen flow rate has reached the preset flow rate value, the flow regulating valve 23 closes and the second vent shut-off valve 12 opens, allowing the hydrogen to be vented through the second hydrogen vent pipe 11. This configuration achieves the recovery of a fixed amount of hydrogen.

[0067] In one embodiment, the delivery element 10 is disposed downstream of the hydrogen buffer tank 7.

[0068] Specifically, refer to Figure 2 The conveying element 10 can be a compressor. A flow regulating valve 23 and a flow meter 24 are also installed between the compressor and the hydrogen scrubbing tower 9 to control the flow rate of hydrogen recovery. When a fixed amount of hydrogen needs to be output, the flow regulating valve 23 opens and the second vent shut-off valve 12 closes, allowing hydrogen to be output until the preset flow rate value is reached. When the flow meter 24 detects that the output hydrogen flow rate has reached the preset flow rate value, the flow regulating valve 23 closes and the second vent shut-off valve 12 opens, allowing the hydrogen to be vented through the second hydrogen vent pipe 11. This configuration achieves the recovery of a fixed amount of hydrogen. The hydrogen first enters the hydrogen buffer tank 7 and then is output through the compressor, eliminating the need for pressure control and enabling the recovery of hydrogen at all pressure levels.

[0069] In one embodiment, the hydrogen recovery device further includes a return channel connecting the upstream and downstream of the conveying element 10, and a third pressure detection element 17 for detecting the inlet pressure of the conveying element 10. The return channel is provided with a second pressure regulating valve 18, which is configured to be opened or closed based on a comparison between the inlet pressure of the conveying element 10 detected by the third pressure detection element 17 and a fourth preset pressure value.

[0070] Specifically, the fourth preset pressure value is set to 0-1 kPa. Taking a setting of 0.5 kPa as an example, when the third pressure detection element 17 detects that the inlet pressure of the conveying element 10 is greater than 0.5 kPa, the second pressure regulating valve 18 opens, allowing gas to flow back to the inlet of the conveying element 10. This increases the gas flow path, effectively reducing the overall resistance and causing the pressure at the inlet of the conveying element 10 to decrease. When the third pressure detection element 17 detects that the inlet pressure of the conveying element 10 is less than 0.5 kPa, the second pressure regulating valve 18 reduces its opening or closes, causing the pressure at the inlet of the pressure conveying element 10 to rise. This setting maintains a stable recovered hydrogen pressure.

[0071] In one embodiment, the hydrogen recovery device further includes a nitrogen filling pipe, which is connected to a first hydrogen venting pipe 6 via a nitrogen filling valve 19 and is configured to protect the hydrogen during the hydrogen venting process.

[0072] Specifically, since hydrogen is a flammable and explosive gas, venting it during thunderstorms poses a fire risk. Therefore, when venting is necessary, the nitrogen filling valve 19 is opened, and the nitrogen in the nitrogen filling pipeline is transported to the first hydrogen venting pipe 6, where it is discharged along with the hydrogen. By adding nitrogen for protection, the hydrogen concentration is reduced, thus lowering the risk of combustion and explosion.

[0073] The chlor-alkali production system disclosed herein includes a hydrogen recovery device as described in any of the above embodiments, and further includes a synthesis furnace 20, a resin production device 21, and a hydrochloric acid production device 22. The synthesis furnace 20 is configured to burn hydrogen and chlorine to synthesize hydrogen chloride. The resin production device 21 is connected to the synthesis furnace 20 and is configured to use most of the hydrogen chloride produced by the synthesis furnace 20 to produce resin. The hydrochloric acid production device 22 is connected to the hydrogen recovery device and is configured to use a small portion of the hydrogen chloride gas to produce hydrochloric acid.

[0074] Specifically, the chlor-alkali production system includes a synthesis furnace 20 for producing hydrogen chloride gas, a resin production unit 21 for producing resin by reacting most of the hydrogen chloride gas with acetylene, a small portion of the hydrogen chloride gas absorbed by an absorber 1 for producing hydrochloric acid, and a hydrogen recovery unit. In addition, it includes an electrolytic cell for producing chlorine, hydrogen and other raw materials for producing hydrogen chloride gas.

[0075] The chlor-alkali production system disclosed herein is capable of producing resin and hydrochloric acid, and can recover and reuse excess hydrogen, reducing the load on water-based hydrogen production.

[0076] Furthermore, to facilitate better understanding, the following section will describe in detail the usage process of the hydrogen recovery device and chlor-alkali production system disclosed herein, using actual application scenarios of the hydrogen recovery device and chlor-alkali production system as examples.

[0077] 1. Synthesis furnace 20 produces hydrogen chloride gas, part of which enters resin production unit 21 and the other part enters absorber 1;

[0078] 2. After being absorbed by absorber 1, the hydrogen chloride gas is carried by circulating water into hydrochloric acid production unit 22 to produce hydrochloric acid, and the remaining gas is transported to separation tank 3 through water jet 2.

[0079] 3. The first pressure detection element 8 is used to detect the pressure at the outlet of the hydraulic jet 2. When the actual pressure value obtained by the first pressure detection element 8 is greater than the first preset pressure value, the first vent shut-off valve 4 is opened and the first recovery shut-off valve 5 is closed, and the gas is vented from the first hydrogen vent pipe 6. When the actual pressure value obtained by the first pressure detection element 8 is less than the first preset pressure value, the first vent shut-off valve 4 is closed and the first recovery shut-off valve 5 is opened.

[0080] 4. After passing through the compressor, the gas pressure is adjusted to 0-1 kPa, and the gas is transported to the hydrogen buffer tank 7;

[0081] 5. When the second pressure detection element 15 detects that the gas pressure in the hydrogen buffer tank 7 is greater than the third preset pressure value, the first pressure regulating valve 16 opens, and the gas in the hydrogen buffer tank 7 is vented through the second hydrogen vent pipe 11; when the second pressure detection element 15 detects that the gas pressure in the hydrogen buffer tank 7 is less than the third preset pressure value, the first pressure regulating valve 16 closes.

[0082] 6. When the actual pressure value obtained by the hydrogen oxygen analyzer 14 is greater than 0.5%, the oxygen content in the hydrogen is high and the hydrogen is impure. The second vent shut-off valve 12 is opened and the second recovery shut-off valve 13 is closed to vent the hydrogen. When the actual pressure value obtained by the hydrogen oxygen analyzer 14 is less than 0.5%, the hydrogen purity is high. The second vent shut-off valve 12 is closed and the second recovery shut-off valve 13 is opened.

[0083] 7. The gas is transported to the hydrogen scrubbing tower 9, where it undergoes further impurity removal before being transported to the hydrogen compressor for recovery.

[0084] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein. The scope of this disclosure is defined by the appended claims.

Claims

1. A hydrogen recovery device, used in chlor-alkali production to recover excess hydrogen, characterized in that, The hydrogen recovery device includes: Absorber (1), which is configured to be connected to the synthesis furnace (20) to absorb hydrogen chloride gas in the tail gas of the synthesis furnace (20); A water jet (2) is configured to input the residual gas from the absorber (1) into a separator (3), which is configured to separate hydrogen and hydrogen chloride gas in the residual gas. The separation tank (3) is connected to the first hydrogen vent pipe (6) through the first vent shut-off valve (4) and to the hydrogen buffer tank (7) through the first recovery shut-off valve (5); The first pressure sensing element (8) is configured to detect the outlet pressure of the hydraulic jet (2), and the first vent shut-off valve (4) and the first recovery shut-off valve (5) are configured to be opened or closed based on the comparison between the actual pressure value obtained by the first pressure sensing element (8) and the first preset pressure value and the second preset pressure value. The first preset pressure value is positive pressure, and the second preset pressure value is negative pressure; The hydrogen recovery device also includes a hydrogen scrubbing tower (9) connected to the hydrogen buffer tank (7), and a conveying element (10) for conveying the gas separated in the separation tank (3) from the separation tank (3) to the hydrogen buffer tank (7) and the hydrogen scrubbing tower (9).

2. The hydrogen recovery device according to claim 1, characterized in that, The first vent shut-off valve (4) is configured to open when the actual pressure value obtained by the first pressure detection element (8) is greater than the first preset pressure value, and to close when the actual pressure value obtained by the first pressure detection element (8) is less than the first preset pressure value. The first recovery shut-off valve (5) is configured to close when the actual pressure value obtained by the first pressure detection element (8) is greater than the first preset pressure value, and to open when the actual pressure value obtained by the first pressure detection element (8) is less than the first preset pressure value.

3. The hydrogen recovery device according to claim 2, characterized in that, The first vent shut-off valve (4) is also configured to open when the actual pressure value obtained by the first pressure sensing element (8) is less than the second preset pressure value; The first recovery shut-off valve (5) is also configured to close when the actual pressure value obtained by the first pressure sensing element (8) is less than the second preset pressure value.

4. The hydrogen recovery device according to claim 3, characterized in that, The hydrogen recovery device also includes: The second hydrogen vent pipe (11) is connected to the hydrogen buffer tank (7) through the second vent shut-off valve (12); The hydrogen buffer tank (7) is connected to the hydrogen scrubbing tower (9) through the second recovery shut-off valve (13); A hydrogen oxygen analyzer (14) is provided between the hydrogen buffer tank (7) and the second hydrogen vent pipe (11). The hydrogen oxygen analyzer (14) is configured to detect the oxygen content of the exhaust gas from the hydrogen buffer tank (7). The second vent shut-off valve (12) and the second recovery shut-off valve (13) are configured to be opened or closed based on the comparison between the actual oxygen content obtained by the hydrogen oxygen analyzer (14) and the preset oxygen content.

5. The hydrogen recovery device according to claim 4, characterized in that, The second vent shut-off valve (12) is configured to open when the actual oxygen content obtained by the hydrogen oxygen analyzer (14) is greater than the preset oxygen content, and to close when the actual oxygen content obtained by the hydrogen oxygen analyzer (14) is less than the preset oxygen content. The second recovery shut-off valve (13) is configured to close when the actual oxygen content obtained by the hydrogen oxygen analyzer (14) is greater than the preset oxygen content, and to open when the actual oxygen content obtained by the hydrogen oxygen analyzer (14) is less than the preset oxygen content.

6. The hydrogen recovery device according to claim 5, characterized in that, The conveying element (10) is disposed on the upstream side of the hydrogen buffer tank (7); The hydrogen recovery device further includes a second pressure detection element (15), which is configured to detect the gas pressure of the hydrogen buffer tank (7); The hydrogen buffer tank (7) is also connected to the second hydrogen vent pipe (11) via a first pressure regulating valve (16). The first pressure regulating valve (16) is configured to be opened or closed based on the comparison between the gas pressure of the hydrogen buffer tank (7) detected by the second pressure sensing element (15) and a third preset pressure value.

7. The hydrogen recovery device according to claim 5, characterized in that, The delivery element (10) is located on the downstream side of the hydrogen buffer tank (7).

8. The hydrogen recovery device according to claim 6 or 7, characterized in that, The hydrogen recovery device also includes a return channel connecting the upstream and downstream of the conveying element (10), and a third pressure detection element (17) for detecting the inlet pressure of the conveying element (10). The return channel is provided with a second pressure regulating valve (18), which is configured to be opened or closed based on the comparison between the inlet pressure of the conveying element (10) detected by the third pressure detection element (17) and a fourth preset pressure value.

9. The hydrogen recovery device according to claim 6 or 7, characterized in that, The hydrogen recovery device also includes a nitrogen filling pipe, which is connected to the first hydrogen venting pipe (6) via a nitrogen filling valve (19) and is configured to protect the hydrogen during the venting process.

10. A chlor-alkali production system, characterized in that, The chlor-alkali production system includes the hydrogen recovery device according to any one of claims 1-9, and further includes: Synthesis furnace (20), which is configured to synthesize hydrogen chloride by burning hydrogen and chlorine; A resin production apparatus (21) is connected to the synthesis furnace (20) and configured to use most of the hydrogen chloride produced by the synthesis furnace (20) for resin production; A hydrochloric acid production unit (22) is connected to the hydrogen recovery unit and is configured to use a small portion of hydrogen chloride gas for the production of hydrochloric acid.

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