Methanol cracking hydrogen production system and control method thereof

Abstract

The invention belongs to the technical field of methanol cracking hydrogen production devices, and particularly relates to a methanol cracking hydrogen production system and a control method thereof. The methanol cracking hydrogen production system comprises a raw material liquid tank, a desalted water tank, a reaction system and a water scrubber, the raw material liquid tank is provided with a methanol inlet, a first washing water inlet and a raw material liquid outlet, the methanol inlet is connected with a methanol inlet pipe, and the methanol inlet pipe is provided with a pneumatic ball valve; the desalted water tank is provided with a desalted water inlet, a second washing water inlet and a desalted water outlet, the desalted water inlet is connected with a desalted water inlet pipe, and the desalted water inlet pipe is provided with a pneumatic ball valve; a washing water outlet of the water scrubber is connected with a washing water outlet pipe, the washing water outlet pipe is divided into two paths, one path is connected with a first washing water inlet through a first pipeline, the other path is connected with a second washing water inlet through a second pipeline, and pneumatic ball valves are arranged on the first pipeline and the second pipeline. Compared with the traditional process, the methanol cracking hydrogen production system and the control method thereof have the advantages of flexible arrangement and thorough leaching.

Description

Technical Field

[0001] This invention belongs to the technical field of methanol cracking hydrogen production equipment, specifically relating to a methanol cracking hydrogen production system and its control method. Background Technology

[0002] Methanol cracking hydrogen production equipment is a device used to convert methanol into hydrogen. Because it can provide a relatively economical and efficient way to produce hydrogen, especially when other traditional hydrogen production methods (such as water electrolysis, natural gas steam reforming, and coal-to-hydrogen) face rising costs or environmental restrictions, its technology and application have been significantly developed and improved over the past few decades.

[0003] In the traditional methanol cracking to hydrogen production process, feedstock preparation and washing are separate processes, such as... Figure 1 As shown, methanol and demineralized water are first introduced from outside the boundary area into methanol tanks and demineralized water tanks inside the boundary area, respectively. Then, the methanol tank is placed at a high position and the demineralized water tank is placed at a low position. Methanol and demineralized water are mixed in the pipeline by gravity flow and then enter the reaction system. During this process, the ratio of methanol to demineralized water is controlled by controlling the flow rate of methanol and the flow rate of raw material liquid. Then, in the reaction system, the decomposition gas is obtained by going through pressurization, heat exchange, reaction and cooling. Finally, the decomposition gas is sent to a water washing tower. A certain amount of demineralized water is drawn from the demineralized water tank using a demineralized water pump to fully wash the decomposition gas to remove unreacted methanol. The washed water is then returned to the demineralized water tank.

[0004] While traditional methods can achieve the mixing of methanol and demineralized water, as well as the rinsing of decomposed gas, their layout requires consideration of the methanol tank's storage height and the length of the methanol-demineralized water mixing pipeline, which can easily lead to uneven mixing. Furthermore, the demineralized water (containing trace amounts of methanol) after rinsing is returned to the demineralized water tank, resulting in trace amounts of methanol in the tank. If the reaction between methanol and demineralized water is incomplete, the methanol content in the water washing tower will be too high, causing methanol accumulation in the demineralized water tank. This necessitates a shutdown to replace the demineralized water in the tank, which is detrimental to the normal operation of the equipment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a methanol cracking hydrogen production system and its control method. The system modifies the process pipelines in the traditional process flow and changes the control method, offering advantages such as flexible layout and thorough rinsing.

[0006] Specifically, the present invention provides the following technical solution: A methanol cracking hydrogen production system includes a feed liquid tank, a demineralized water tank, a reaction system, and a water washing tower; The raw material tank is equipped with a methanol inlet, a first washing water inlet, and a raw material outlet; the methanol inlet is connected to a methanol inlet pipe, and a methanol pneumatic ball valve is installed on the methanol inlet pipe; the raw material outlet is connected to the inlet of the reaction system through a pipeline, and the outlet of the reaction system is connected to the decomposition gas inlet of the water washing tower through a pipeline. The demineralized water tank is equipped with a demineralized water inlet, a second washing water inlet, and a demineralized water outlet; the demineralized water inlet is connected to a demineralized water inlet pipe, and a demineralized water pneumatic ball valve is installed on the demineralized water inlet pipe; the demineralized water outlet is connected to the washing water inlet of the water washing tower through a pipeline. The washing water outlet of the washing tower is connected to the washing water outlet pipe, which is divided into two paths: one path is connected to the first washing water inlet through the first pipe, and the other path is connected to the second washing water inlet through the second pipe; a washing water pneumatic ball valve is respectively installed on the first pipe and the second pipe.

[0007] The present invention provides a methanol cracking hydrogen production system, which utilizes the high pressure of the water washing tower and the boundary methanol to transport the pressurized methanol in the boundary and the washing water discharged from the water washing tower to the feed liquid tank in a certain proportion, and utilizes the infinite miscibility of methanol and demineralized water to achieve the mixing of methanol and demineralized water. Pneumatic ball valves are installed on the methanol inlet pipe, the first pipeline, and the second pipeline to control the liquid level in the feed tank and prevent overflow. When the liquid level in the feed tank reaches the set high level, the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline are closed, and the washing water pneumatic ball valve on the second pipeline is opened, so that the washing water discharged from the water washing tower is delivered to the demineralized water tank. When the feed liquid is consumed to the set low level, the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline are reopened, and the washing water pneumatic ball valve on the second pipeline is closed. A pneumatic ball valve is installed on the demineralized water inlet pipe to control the liquid level in the demineralized water tank and prevent demineralized water from overflowing. When the liquid level in the demineralized water tank reaches the set high level, the pneumatic ball valve is closed; when the demineralized water is consumed down to the set low level, the pneumatic ball valve is reopened.

[0008] Preferably, a desalination pump is installed on the pipeline connecting the desalination outlet and the washing water inlet of the washing tower. The desalination pump continuously draws a certain flow rate of desalination water and delivers it to the washing tower for rinsing.

[0009] Preferably, the methanol inlet pipe is also equipped with a methanol regulating valve to regulate the flow rate of methanol, thereby controlling the mixing ratio of methanol and washing water in the raw material tank.

[0010] Preferably, the washing water outlet pipe is equipped with a washing water regulating valve to regulate the discharge flow rate of the washing water, thereby controlling the liquid level of the water washing tower.

[0011] Preferably, both the raw material tank and the demineralized water tank are equipped with level gauges.

[0012] The present invention also provides a control method for the above-mentioned methanol cracking hydrogen production system, comprising: When the liquid level in the raw material tank is greater than or equal to the preset high liquid level, close the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline, and open the washing water pneumatic ball valve on the second pipeline. The washing water discharged from the water washing tower is then transported to the demineralized water tank. When the liquid level in the raw material tank is lower than or equal to the preset low liquid level, reopen the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline, and close the washing water pneumatic ball valve on the second pipeline. When the liquid level in the demineralized water tank is greater than or equal to the preset high liquid level, close the demineralized water pneumatic ball valve; when the liquid level in the demineralized water tank is lower than or equal to the preset low liquid level, reopen the demineralized water pneumatic ball valve.

[0013] The beneficial effects achieved by this invention are as follows: 1. The present invention provides a methanol cracking hydrogen production system and its control method, which utilizes the high pressure on both sides of the water washing tower and the boundary methanol to mix the washing water of the water washing tower with the boundary methanol in a certain proportion to obtain a feed liquid stored in an atmospheric pressure feed liquid tank. The feed liquid tank can be flexibly arranged anywhere and is no longer limited by height. 2. The present invention provides a methanol cracking hydrogen production system and its control method. During the operation of the system, the flow rates of methanol and washing water can be controlled so that the washing water does not need to flow into the demineralized water tank, thereby ensuring that all the washing water containing trace amounts of methanol in the water washing tower enters the feed liquid tank. The water in the demineralized water tank for rinsing is all methanol-free demineralized water, which can more thoroughly remove unreacted methanol from the decomposition gas, and can achieve better rinsing effect without changing the original demineralized water tank volume and demineralized water pump power. 3. The methanol cracking hydrogen production system and its control method provided by the present invention avoid frequent shutdowns to replace the demineralized water in the demineralized water tank, improve the safety of the entire process, and make the product quality more stable. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of a traditional methanol cracking hydrogen production system. In the diagram, 102 is the demineralized water tank, 103 is the water washing tower, 104 is the demineralized water pump, 105 is the reaction system, 106 is the methanol tank, 201 is the methanol regulating valve on the methanol inlet pipe, 203 is the washing water regulating valve, 207 is the washing water pneumatic ball valve, 205 is the demineralized water pneumatic ball valve, 208 is the methanol regulating valve on the methanol outlet pipe, 302 is the demineralized water tank level gauge, 303 is the water washing tower level gauge, and 304 is the methanol tank level gauge.

[0015] Figure 2This invention provides a process flow diagram of a methanol cracking hydrogen production system; in the diagram, 101 is a feed liquid tank, 102 is a demineralized water tank, 103 is a water washing tower, 104 is a demineralized water pump, 105 is a reaction system, 201 is a methanol regulating valve on the methanol inlet pipe, 202 is a methanol pneumatic ball valve, 203 is a washing water regulating valve, 204 is a washing water pneumatic ball valve on the first pipeline, 206 is a washing water pneumatic ball valve on the second pipeline, 205 is a demineralized water pneumatic ball valve, 301 is a feed liquid tank level gauge, 302 is a demineralized water tank level gauge, and 303 is a water washing tower level gauge. Detailed Implementation

[0016] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in the field, or in accordance with the product manual.

[0017] Example 1 Example 1 provides a methanol cracking hydrogen production system and its control method, such as Figure 2 As shown, it includes: a raw material liquid tank 101, a demineralized water tank 102, a reaction system 105, and a water washing tower 103; The raw material tank 101 is provided with a methanol inlet, a first washing water inlet and a raw material outlet; the methanol inlet is connected to a methanol inlet pipe, and the methanol inlet pipe is provided with a methanol regulating valve 201 and a methanol pneumatic ball valve 202; the raw material outlet is connected to the inlet of the reaction system 105 through a pipeline, and the outlet of the reaction system 105 is connected to the decomposition gas inlet of the water washing tower 103 through a pipeline. The demineralized water tank 102 is provided with a demineralized water inlet, a second washing water inlet, and a demineralized water outlet; the demineralized water inlet is connected to a demineralized water inlet pipe, and a demineralized water pneumatic ball valve 205 is provided on the demineralized water inlet pipe; the demineralized water outlet is connected to the washing water inlet of the water washing tower 103 through a pipeline, and a demineralized water pump 104 is provided on the pipeline. The washing water outlet of the washing tower 103 is connected to the washing water outlet pipe, and the washing water outlet pipe is equipped with a washing water regulating valve 203; the washing water outlet pipe is divided into two paths, one path is connected to the first washing water inlet through the first pipeline, and the other path is connected to the second washing water inlet through the second pipeline; the first pipeline and the second pipeline are respectively equipped with a washing water pneumatic ball valve 204 and a washing water pneumatic ball valve 206. The raw material tank 101, the demineralized water tank 102, and the water washing tower 103 are respectively equipped with a raw material tank level gauge 301, a demineralized water tank level gauge 302, and a water washing tower level gauge 303.

[0018] The control method for the methanol cracking hydrogen production system described in this embodiment is as follows: Methanol under pressure in the boundary area is simultaneously and proportionally transported to the atmospheric pressure raw material tank 101 along with the washing water from the outlet of the water washing tower 103 under the flow control of the methanol regulating valve 201, thereby achieving the mixing of methanol and demineralized water. The mixed methanol-water solution is pressurized and sent to the reaction system 105, where it undergoes pressurization, heat exchange, reaction, and cooling to obtain decomposition gas. Finally, the decomposition gas is sent to the water washing tower 103. The demineralized water pump 104 continuously draws a certain flow rate of fresh demineralized water and sends it to the water washing tower 103 for rinsing to remove unreacted methanol from the decomposition gas. The rinsed decomposition gas is then sent to the pressure swing adsorption device for further purification. The rinsing water containing trace amounts of methanol is continuously supplied to the raw material tank 101. When the liquid level in the raw material tank 101 is greater than or equal to the preset high liquid level value of the raw material liquid level gauge 301, the methanol pneumatic ball valve 202 on the methanol inlet pipe and the washing water pneumatic ball valve 204 on the first pipeline are closed, and the washing water pneumatic ball valve 206 on the second pipeline is opened; when the liquid level in the raw material tank 101 is lower than or equal to the preset low liquid level value of the raw material liquid level gauge 301, the methanol pneumatic ball valve 202 and the washing water pneumatic ball valve 204 on the first pipeline are reopened, and the washing water pneumatic ball valve 206 on the second pipeline is closed. When the liquid level in the demineralized water tank 102 is greater than or equal to the preset high liquid level value of the demineralized water tank level gauge 302, the demineralized water pneumatic ball valve 205 on the demineralized water pipeline is closed; when the demineralized water is consumed down to the preset low liquid level of the demineralized water tank level gauge 302, the demineralized water pneumatic ball valve 205 is opened again.

[0019] After long-term operation, the methanol content in the decomposed gas after rinsing of the methanol cracking hydrogen production system described in Example 1 is 0.01%~0.02%.

[0020] Comparative Example 1 Comparative Example 1 provides a conventional methanol cracking hydrogen production system and its control method, such as Figure 1 As shown, it includes: methanol tank 106, demineralized water tank 102, reaction system 105 and water washing tower 103; The methanol tank 106 is provided with a methanol inlet and a methanol outlet; the methanol inlet is connected to a methanol inlet pipe, and a methanol regulating valve 201 is provided on the methanol inlet pipe; the methanol outlet is connected to a methanol outlet pipe, and a methanol regulating valve 208 is provided on the methanol outlet pipe. The demineralized water tank 102 is provided with a demineralized water inlet, a washing water inlet, a first demineralized water outlet, and a second demineralized water outlet; the demineralized water inlet is connected to a demineralized water inlet pipe, and a demineralized water pneumatic ball valve 205 is provided on the demineralized water inlet pipe; the first demineralized water outlet is connected to the washing water inlet of the water washing tower 103 through a pipeline, and a demineralized water pump 104 is provided on the pipeline; the second demineralized water outlet is connected to the inlet of the reaction system 105 after being merged with the methanol outlet pipe through a pipeline, and the outlet of the reaction system 105 is connected to the decomposition gas inlet of the water washing tower 103 through a pipeline; The washing water outlet of the washing tower 103 is connected to the washing water inlet through a washing water outlet pipe. The washing water outlet pipe is equipped with a washing water pneumatic ball valve 207 and a washing water regulating valve 203. The methanol tank 106, the demineralized water tank 102, and the water washing tower 103 are respectively equipped with methanol tank level gauge 304, demineralized water tank level gauge 302, and water washing tower level gauge 303.

[0021] The control method of the methanol cracking hydrogen production system described in Comparative Example 1 is as follows: First, methanol and demineralized water are introduced from outside the boundary area into methanol tank 106 and demineralized water tank 102 inside the boundary area, respectively. Then, methanol tank 106 is placed at a high position to overcome the resistance of methanol regulating valve 208, and demineralized water tank 102 is placed at a low position. Methanol and demineralized water are mixed in the pipeline by gravity flow and then pressurized into reaction system 105. Next, in reaction system 105, decomposition gas is obtained by going through pressurization, heat exchange, reaction and cooling. Finally, the decomposition gas is sent to water washing tower 103. A certain amount of demineralized water is drawn from demineralized water tank 102 using demineralized water pump 104 to fully wash the decomposition gas to wash away unreacted methanol. The washed water is returned to demineralized water tank 102.

[0022] After long-term operation, the methanol content in the decomposed gas after rinsing of the methanol cracking hydrogen production system described in Comparative Example 1 was 0.02%~0.04%, which was significantly higher than that in Example 1.

[0023] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A methanol cracking hydrogen production system, characterized in that, This includes a raw material tank, a demineralized water tank, a reaction system, and a water washing tower; The raw material tank is equipped with a methanol inlet, a first washing water inlet, and a raw material outlet; the methanol inlet is connected to a methanol inlet pipe, and a methanol pneumatic ball valve is installed on the methanol inlet pipe; the raw material outlet is connected to the inlet of the reaction system through a pipeline, and the outlet of the reaction system is connected to the decomposition gas inlet of the water washing tower through a pipeline. The demineralized water tank is equipped with a demineralized water inlet, a second washing water inlet, and a demineralized water outlet; the demineralized water inlet is connected to a demineralized water inlet pipe, and a demineralized water pneumatic ball valve is installed on the demineralized water inlet pipe; the demineralized water outlet is connected to the washing water inlet of the water washing tower through a pipeline. The washing water outlet of the washing tower is connected to the washing water outlet pipe, which is divided into two paths: one path is connected to the first washing water inlet through the first pipe, and the other path is connected to the second washing water inlet through the second pipe; a washing water pneumatic ball valve is respectively installed on the first pipe and the second pipe.

2. The methanol cracking hydrogen production system according to claim 1, characterized in that, A desalination pump is installed on the pipeline connecting the desalination outlet to the washing water inlet of the washing tower.

3. The methanol cracking hydrogen production system according to claim 1 or 2, characterized in that, The methanol inlet pipe is also equipped with a methanol regulating valve.

4. The methanol cracking hydrogen production system according to claim 1 or 2, characterized in that, The washing water outlet pipe is equipped with a washing water regulating valve.

5. The methanol cracking hydrogen production system according to claim 1 or 2, characterized in that, Both the raw material tank and the demineralized water tank are equipped with level gauges.

6. The control method for the methanol cracking hydrogen production system according to any one of claims 1-5, characterized in that, include: When the liquid level in the raw material tank is greater than or equal to the preset high liquid level, close the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline, and open the washing water pneumatic ball valve on the second pipeline. The washing water discharged from the water washing tower is then transported to the demineralized water tank. When the liquid level in the raw material tank is lower than or equal to the preset low liquid level, reopen the methanol pneumatic ball valve and the washing water pneumatic ball valve on the first pipeline, and close the washing water pneumatic ball valve on the second pipeline. When the liquid level in the demineralized water tank is greater than or equal to the preset high liquid level, close the demineralized water pneumatic ball valve; when the liquid level in the demineralized water tank is lower than or equal to the preset low liquid level, reopen the demineralized water pneumatic ball valve.

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