A safe and efficient hydrogen utilization system for chlor-alkali processes

Abstract

This application discloses a safe and efficient hydrogen utilization system for chlor-alkali processes, including a main hydrogen pipeline connected to a hydrogen scrubbing tower, and a hydrogen water seal branch, a boiler hydrogen supply branch, and a hydrogen pressure regulating branch connected in parallel to its output end. The boiler hydrogen supply branch is equipped with a hydrogen cooler and a shut-off valve and flow regulating valve assembly including a bypass pipeline; the hydrogen pressure regulating branch is equipped with a hydrogen regulating valve leading to a hydrogen vent. The nitrogen replacement unit includes a main nitrogen pipeline and branch pipelines, each equipped with shut-off valves, check valves, etc., for nitrogen purging during start-up, shutdown, and emergency conditions. The system offers significant advantages: the addition of a hydrogen cooler stabilizes hydrogen temperature and flow; the addition of a bypass valve and flow meter to the flow regulating valve assembly allows for precise regulation and eliminates hydrogen venting waste; the well-designed nitrogen replacement unit and safety interlock mechanism eliminate the risk of explosion. This system effectively improves the safety and efficiency of hydrogen utilization.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen efficient utilization technology, specifically to a hydrogen safe and efficient utilization system applied to chlor-alkali processes. Background Technology

[0002] During the production of caustic soda in chlor-alkali chemical enterprises, a large amount of hydrogen is produced as a byproduct; for example, approximately 0.025 tons of hydrogen are produced for every ton of caustic soda produced. As a major producer of chlor-alkali, my country has a considerable hydrogen production capacity, but there are currently many technical challenges in utilizing hydrogen.

[0003] In existing hydrogen utilization processes, pressure regulating valves are often installed in the main hydrogen pipeline to maintain pressure by venting, in order to ensure stable hydrogen pressure. However, hydrogen pipelines are long, and their temperature is easily affected by the external environment. Furthermore, hydrogen flow meters lack temperature compensation functions, resulting in large fluctuations in the actual hydrogen flow and reduced efficiency of hydrogen utilization equipment.

[0004] Meanwhile, some processes pose serious safety risks. Hydrogen, after being adjusted by the hydrogen pressure regulating valve, directly enters the hydrogen boiler. If the boiler malfunctions and shuts down, the hydrogen may mix with air, posing an explosion hazard. Furthermore, current hydrogen utilization efficiency technologies are flawed, making it difficult to achieve high-efficiency utilization while ensuring safety. These technical problems urgently need to be solved. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the above-mentioned technical defects and provide a safe and efficient hydrogen utilization system for chlor-alkali processes.

[0006] To solve the above-mentioned technical problems, the technical solution provided by this utility model is: a safe and efficient hydrogen utilization system applied to chlor-alkali processes, comprising:

[0007] The main hydrogen pipeline connects to the hydrogen scrubbing tower at its inlet end.

[0008] The hydrogen water seal branch, the boiler hydrogen supply branch, and the hydrogen pressure regulating branch are connected in parallel to the output end of the hydrogen main pipe.

[0009] The boiler hydrogen supply branch is provided with the following in sequence:

[0010] Hydrogen cooler,

[0011] A first shut-off valve, a hydrogen flow regulating valve, a second shut-off valve, and a third shut-off valve are connected in series. A bypass line is connected in parallel to one side of the hydrogen flow regulating valve. A bypass regulating valve and a hydrogen flow meter are installed on the bypass line.

[0012] The outlet of the hydrogen pressure regulating branch leads to the hydrogen vent, and a hydrogen regulating valve is installed on it.

[0013] The nitrogen replacement unit includes:

[0014] The nitrogen main pipeline is connected to the inlet of the hydrogen-fired boiler at its output end and is equipped with a fifth shut-off valve;

[0015] The nitrogen branch line has its input end connected to the main nitrogen pipeline and its output end connected to the pipeline section between the first shut-off valve and the hydrogen flow regulating valve, and is equipped with a fourth shut-off valve.

[0016] The venting pipeline is located between the second shut-off valve and the third shut-off valve, and is equipped with a sixth shut-off valve.

[0017] In the preferred embodiment of the above technical solution, the cooling medium of the hydrogen cooler is chilled water, used to maintain the outlet hydrogen temperature ≤30℃.

[0018] In the preferred embodiment of the above technical solution, the bypass regulating valve is located on the pipe section between the first shut-off valve and the second shut-off valve, with its inlet end located upstream of the hydrogen flow regulating valve and its outlet end located downstream of the hydrogen flow regulating valve.

[0019] In the preferred embodiment of the above technical solution, a water seal tank is provided on the hydrogen water seal branch, with its inlet extending below the liquid surface inside the water seal tank and its outlet located in the gas phase space above the liquid surface to form a liquid seal.

[0020] In the preferred embodiment of the above technical solution, the hydrogen flow meter is a vortex flow meter with temperature compensation, and its signal output terminal is connected to the control terminal of the bypass regulating valve.

[0021] In the preferred embodiment of the above technical solution, both the main nitrogen pipeline and the nitrogen branch pipelines are equipped with check valves.

[0022] In the preferred embodiment of the above technical solution, a remote pressure gauge is also provided on the nitrogen main pipeline.

[0023] The hydrogen safety and efficiency utilization system proposed in this application has significant advantages. First, the addition of a hydrogen cooler stabilizes the hydrogen temperature, ensuring a stable flow rate and meeting the boiler's maximum load production, thus solving the problem of inaccurate flow and reduced equipment efficiency caused by temperature fluctuations. Second, the addition of a bypass valve and flow meter to the flow regulating valve group ensures balanced main pipe pressure through precise adjustment while preventing hydrogen venting and waste. Third, a comprehensive nitrogen purging unit and safety interlock mechanism are designed. During start-up, shutdown, and emergency conditions, dual-path nitrogen purging and safety interlock actions remove residual hydrogen and eliminate the risk of explosion. The cleverly positioned valve group ensures the safe and efficient operation of the hydrogen system, effectively overcoming the shortcomings of existing technologies and improving the safety and efficiency of hydrogen utilization. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a hydrogen safe and efficient utilization system applied to the chlor-alkali process according to this application.

[0025] As shown in the diagram: 1. Hydrogen main pipeline, 2. Hydrogen water seal branch, 3. Boiler hydrogen supply branch, 4. Hydrogen pressure regulating branch, 5. Hydrogen cooler, 6. Bypass pipeline, 7. Remote pressure gauge, 8. Nitrogen main pipeline, 9. Nitrogen branch pipeline, 10. Vent pipeline, 11. Water seal tank, F1. First shut-off valve, F2. Hydrogen flow regulating valve, F3. Second shut-off valve, F4. Third shut-off valve, F5. Fourth shut-off valve, F6. Fifth shut-off valve, F7. Sixth shut-off valve, F8. Bypass regulating valve, F9. Hydrogen regulating valve, F10. Hydrogen flow meter, F11. Check valve. Detailed Implementation

[0026] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals.

[0027] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0028] To make the content of this utility model easier to understand, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0029] See attached document Figure 1 This application provides a safe and efficient hydrogen utilization system for use in chlor-alkali processes, comprising:

[0030] Hydrogen main pipe 1, as the core transportation channel of the system, is connected to the hydrogen scrubbing tower at its input end to receive hydrogen purified by alkaline mist, ensuring that the purity of the hydrogen entering the subsequent branches meets the process requirements (to avoid corrosion of valves, flow meters and other equipment by alkaline mist).

[0031] Three functional branches are set in parallel at the output end of the hydrogen main pipe 1: hydrogen water seal branch 2, boiler hydrogen supply branch 3, and hydrogen pressure regulation branch 4, so as to realize the synergistic effect of safe depressurization, efficient utilization and pressure redundancy control of hydrogen.

[0032] Boiler hydrogen supply branch 3 is the core pathway for achieving efficient hydrogen utilization. Its structural design is directly related to the operational stability and safety of the hydrogen-fired boiler, specifically including:

[0033] Hydrogen cooler 5, located at the beginning of the branch line, uses chilled water as the cooling medium to regulate the temperature of hydrogen. The cooler's outlet pipe is equipped with a temperature sensor, which is interlocked with the chilled water regulating valve. When the detected hydrogen temperature exceeds 30°C, the chilled water flow rate is automatically increased; when the temperature is below 30°C, the flow rate is reduced, ensuring the hydrogen temperature remains stable below 30°C. This design effectively avoids hydrogen density changes caused by ambient temperature fluctuations, solves the flow metering deviation problem caused by uncompensated temperature in existing technologies, provides a stable medium basis for subsequent flow regulation, and ensures that the hydrogen-fired boiler always operates within its design load range.

[0034] Boiler hydrogen supply branch 3 is connected in series with the first shut-off valve F1, hydrogen flow regulating valve F2, second shut-off valve F3, and third shut-off valve F4, forming a "shut-off-regulation-shut-off" safety control chain. Among them:

[0035] Hydrogen flow regulating valve F2, as the main regulating element, is responsible for setting the basic hydrogen flow rate of the hydrogen-fired boiler to ensure the stability of the boiler's core load.

[0036] To achieve dynamic fine-tuning of the hydrogen main pipe pressure, a bypass line 6 is connected in parallel to the hydrogen flow regulating valve F2. A bypass regulating valve F8 and a hydrogen flow meter F10 are installed on this line. The inlet of the bypass regulating valve F8 is located upstream of the hydrogen flow regulating valve F2, and the outlet is located downstream of F2 (i.e., between the first shut-off valve F1 and the second shut-off valve F3). This design allows bypass hydrogen to directly flow into the main pipe and enter the boiler, avoiding the problem of "excess hydrogen venting" in traditional regulation. When the main pipe pressure fluctuates, the bypass regulating valve F8 can supplement or divert hydrogen through minor adjustments without interfering with the base flow rate set by the hydrogen flow regulating valve F2. This ensures the main pipe pressure balance while directing all hydrogen into the boiler for combustion, avoiding resource waste.

[0037] Hydrogen pressure regulating branch 4: As a redundant guarantee for system pressure regulation, its outlet is connected to the hydrogen vent and equipped with a hydrogen regulating valve F9. When the valve group regulation of the boiler hydrogen supply branch cannot meet the pressure balance requirements, the hydrogen regulating valve F9 can maintain the safe pressure of the main pipe by moderate venting (only activated under extreme conditions to minimize waste).

[0038] The nitrogen purging unit, designed for safety protection during start-up, shutdown, and emergency conditions of hydrogen-fired boilers, features a dual-path nitrogen purging structure, including:

[0039] Nitrogen main line 8 is directly connected to hydrogen boiler inlet A and equipped with fifth shut-off valve F6, which can directly introduce nitrogen into the boiler furnace for gas replacement of the boiler body.

[0040] Nitrogen branch line 9 branches off from nitrogen main line 8 and connects to the section between first shut-off valve F1 and hydrogen flow regulating valve F2. It is equipped with fourth shut-off valve F5 for purging the pipeline of the boiler hydrogen supply branch line with nitrogen.

[0041] Both the main nitrogen pipeline 8 and the nitrogen branch pipeline 9 are equipped with check valves F11, which can effectively prevent hydrogen from flowing back into the nitrogen pipeline and forming an explosive mixture, thus blocking the risk of cross-contamination from a hardware perspective. At the same time, the remote pressure gauge 7 on the main nitrogen pipeline 8 can monitor the nitrogen pressure in real time to ensure that the nitrogen pressure is stable during purging (avoiding incomplete replacement due to insufficient pressure).

[0042] Vent line 10 is located between the second shut-off valve F3 and the third shut-off valve F4, and is equipped with a sixth shut-off valve F7. It serves as an exhaust gas discharge channel during nitrogen purging, ensuring that the displaced mixed gas (air and residual hydrogen) can be safely discharged from the system.

[0043] In one embodiment, the hydrogen water seal branch 2 is equipped with a water seal tank 11, with its inlet extending below the liquid surface inside the water seal tank 11 and its outlet located in the gas phase space above the liquid surface to form a liquid seal. This application uses the water seal tank 11 to achieve passive safety pressure relief. When the pressure in the hydrogen main pipe 1 suddenly increases, high-pressure hydrogen can break through the liquid seal and be released from the outlet, preventing overpressure in the pipeline. Under normal operating conditions, the liquid seal can prevent outside air from backflowing into the hydrogen pipeline, ensuring hydrogen purity.

[0044] In one embodiment, the hydrogen flow meter F10 is a temperature-compensated vortex flow meter. Its core advantage is that it can correct the density deviation caused by the change in hydrogen temperature in real time (by converting the volumetric flow rate into the mass flow rate under standard conditions through a built-in algorithm) and transmit the metering signal to the control terminal of the bypass regulating valve F8 to form a "metering-regulation" closed loop, making the pressure fine adjustment of the bypass regulating valve F8 more accurate and further improving the system pressure stability.

[0045] Working principle:

[0046] When the hydrogen-fired boiler is started up, this application closes the third shut-off valve F4 and the fifth shut-off valve F6 through a pre-set program, and then opens the sixth shut-off valve F7, the second shut-off valve F3, the hydrogen flow regulating valve F2, the bypass regulating valve F8, and the fourth shut-off valve F5. Nitrogen is then introduced from the nitrogen main pipeline 8, and the nitrogen main pipeline 8 enters the boiler hydrogen supply branch 3 through the nitrogen branch pipeline 9 for nitrogen purging and replacement.

[0047] After the purging is completed, close the fourth shut-off valve F5, the sixth shut-off valve F7, the second shut-off valve F3, the hydrogen flow regulating valve F2, and the bypass regulating valve F8; open the fifth shut-off valve F6 and introduce nitrogen from the nitrogen main pipeline 8 to purge the boiler with nitrogen for purging. This ensures safe start-up conditions for the hydrogen-fired boiler.

[0048] After the replacement is completed, enter the start-up mode: close the fourth shut-off valve F5 and the fifth shut-off valve F6, open the first shut-off valve F1, the second shut-off valve F3, and the third shut-off valve F4. Hydrogen enters the hydrogen-fired boiler through the hydrogen flow regulating valve F2. When the hydrogen-fired boiler reaches the rated output, open the bypass regulating valve F8 and start automatic operation according to the setting of the hydrogen flow meter F10.

[0049] When a hydrogen-fired boiler suddenly trips due to a malfunction, the system immediately triggers a safety interlock: the third shut-off valve F4 (shutting off the boiler's hydrogen inlet) and the first shut-off valve F1 (blocking the main hydrogen supply) are closed, and the fourth shut-off valve F5 (nitrogen supply to the pipeline) is opened. Nitrogen is discharged through the hydrogen flow regulating valve F2, the second shut-off valve F3, and the bypass regulating valve F8, exiting through the sixth shut-off valve F7 to remove residual hydrogen from the pipeline. Simultaneously, the fifth shut-off valve F6 opens to displace nitrogen from the hydrogen-fired boiler, preventing hydrogen from mixing with air in the furnace and eliminating the risk of explosion at its source. This ensures the safe shutdown of the hydrogen-fired boiler in the event of an abnormal shutdown.

[0050] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A safe and efficient hydrogen utilization system for use in chlor-alkali processes, characterized in that, include: Hydrogen main pipe (1), with the input end connected to a hydrogen scrubbing tower; Hydrogen water seal branch (2), boiler hydrogen supply branch (3) and hydrogen pressure regulating branch (4) are connected in parallel to the output end of the hydrogen main pipe (1); The boiler hydrogen supply branch (3) is provided with the following in sequence: Hydrogen cooler (5); A first shut-off valve (F1), a hydrogen flow regulating valve (F2), a second shut-off valve (F3), and a third shut-off valve (F4) are connected in series. A bypass line (6) is connected in parallel on one side of the hydrogen flow regulating valve (F2). A bypass regulating valve (F8) and a hydrogen flow meter (F10) are provided on the bypass line (6). The outlet of the hydrogen pressure regulating branch (4) leads to the hydrogen vent, and a hydrogen regulating valve (F9) is provided on it; The nitrogen replacement unit includes: The nitrogen main pipeline (8) is connected to the hydrogen boiler inlet (A) at its output end and is equipped with a fifth shut-off valve (F6). The nitrogen branch line (9) has its input end connected to the nitrogen main line (8) and its output end connected to the pipe section between the first shut-off valve (F1) and the hydrogen flow regulating valve (F2), and is equipped with a fourth shut-off valve (F5). A venting line (10) is located between the second shut-off valve (F3) and the third shut-off valve (F4), and a sixth shut-off valve (F7) is provided.

2. The hydrogen safe and efficient utilization system applied to the chlor-alkali process according to claim 1, characterized in that, The cooling medium of the hydrogen cooler (5) is chilled water, which is used to maintain the outlet hydrogen temperature ≤30℃.

3. The hydrogen safe and efficient utilization system applied to the chlor-alkali process according to claim 1, characterized in that, The bypass regulating valve (F8) is located on the pipe section between the first shut-off valve (F1) and the second shut-off valve (F3), with its inlet end located upstream of the hydrogen flow regulating valve (F2) and its outlet end located downstream of the hydrogen flow regulating valve (F2).

4. A safe and efficient hydrogen utilization system for chlor-alkali processes according to claim 1, characterized in that, The hydrogen water seal branch (2) is equipped with a water seal tank (11), with its inlet extending below the liquid surface inside the water seal tank (11) and its outlet located in the gas phase space above the liquid surface to form a liquid seal.

5. A safe and efficient hydrogen utilization system for chlor-alkali processes according to claim 1, characterized in that, The hydrogen flow meter (F10) is a temperature-compensated vortex flow meter, and its signal output terminal is connected to the control terminal of the bypass regulating valve (F8).

6. A safe and efficient hydrogen utilization system for chlor-alkali processes according to claim 1, characterized in that, Both the main nitrogen pipeline (8) and the nitrogen branch pipeline (9) are equipped with check valves (F11).

7. A safe and efficient hydrogen utilization system for chlor-alkali processes according to claim 6, characterized in that, The nitrogen main pipeline (8) is also equipped with a remote pressure gauge (7).

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