Hydrogen recovery system and method for a hydrogen refueling station

Abstract

The application belongs to the field of hydrogen energy, and relates to a hydrogen recovery system and method of a hydrogen refueling mother station. An outlet of a hydrogen purification device is divided into two streams. One stream is connected with a compression and filling device through a product gas pipeline, a product gas regulating valve HV3 is installed on the product gas pipeline, the other stream is connected with a fine synthesis gas main pipeline through a recovery hydrogen pipeline, a recovery hydrogen regulating valve HV4 and a recovery hydrogen flow meter FI4 are installed on the recovery hydrogen pipeline in sequence, and after calculation by a calculator KY1, an unconverted gas supplement amount FI5 signal and a converted gas supplement amount FI6 signal are output. When hydrogen compression and filling devices stop filling, hydrogen purified by the hydrogen purification device is introduced into the fine synthesis gas main pipeline of a butyl octanol device, so that loss caused by hydrogen venting when the hydrogen purification device stops or does not stop is avoided.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy and relates to hydrogen production, especially hydrogen recovery systems and methods for hydrogen refueling mother stations. Background Technology

[0002] The hydrogen refueling mother station process is as follows: Industrial by-product hydrogen from chemical enterprises is first purified by a hydrogen purification unit, and the purity (mole fraction) of the purified hydrogen can reach 99.999% or higher. Then it enters the hydrogen compressor for compression, and the hydrogen pressure is compressed to 20MPa before entering the filling area for filling long tube trucks and container compartments.

[0003] like Figure 1 As shown: Industrial by-product hydrogen is connected to the inlet of the hydrogen purification unit via raw material gas pipeline 1, and the outlet of the hydrogen purification unit is connected to the compression and filling device via product gas pipeline 2. A product gas regulating valve HV3 is installed on product gas pipeline 2.

[0004] The upstream syngas process is as follows: The un-shifted gas system from the low-temperature methanol wash unit produces purified un-shifted gas, and the shifted gas system from the low-temperature methanol wash unit produces purified shifted gas. The un-shifted gas contains a high concentration of CO and a small amount of hydrogen, while the shifted gas contains a high concentration of hydrogen and a small amount of CO. These two components are mixed in a specific ratio to achieve a hydrogen-to-carbon ratio between 1.01 and 1.05, and then fed into the syngas mains before being sent to the butanol / octanol unit.

[0005] like Figure 2 As shown: The unconverted system is connected to the refined syngas main pipe 4 via unconverted line 3, and the converted gas system is connected to the refined syngas main pipe 4 via converted gas line 5. Unconverted gas regulating valve HV1 and unconverted gas flow meter FI1 are installed sequentially on unconverted gas line 3; converted gas regulating valve HV2 and converted gas flow meter FI2 are installed sequentially on converted gas line 5; and refined syngas flow meter FI3 and refined syngas analyzer AI3 are installed sequentially on the refined syngas main pipe 4.

[0006] Currently, hydrogen production at hydrogen refueling mother stations cannot be continuous or operate at high capacity. Frequent start-ups and shutdowns lead to the following problems:

[0007] 1. It takes nearly two hours for the hydrogen purification unit to go from shutdown to normal operation, which will seriously affect the hydrogen supply speed of subsequent hydrogen refueling stations, resulting in untimely gas supply to the refueling stations and affecting their use.

[0008] 2. Each start-up and shutdown of the hydrogen purification unit results in the loss of approximately 3,000-5,000 standard cubic meters of hydrogen, causing significant waste.

[0009] 3. During the hydrogen production process, if the long-tube truck fails to arrive in time for filling, the hydrogen purification unit can only operate at the lowest load, which leads to the emission of a large amount of product gas and significantly increases operating costs.

[0010] 4. Frequent start-up and shutdown can cause the adsorbent in the purification unit to easily become pulverized, thus affecting the service life of the adsorbent.

[0011] 5. Frequent start-up and shutdown will cause large fluctuations in the gas volume upstream of the purification unit, affecting the stable operation of the upstream. Summary of the Invention

[0012] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hydrogen recovery system and method for a hydrogen refueling mother station. When the hydrogen compression and filling device stops filling, the hydrogen purified by the hydrogen purification device is introduced into the main syngas pipe of the butanol and octanol unit, thus avoiding the loss of hydrogen due to hydrogen venting caused by the hydrogen purification device stopping or not stopping.

[0013] The technical solution for achieving the objective of this invention is as follows:

[0014] The first aspect of the present invention is to provide a hydrogen recovery system for a hydrogen refueling mother station. The unconverted gas system from the cryogenic methanol washing unit is connected to the refined syngas main pipe via an unconverted gas pipeline. An unconverted gas analyzer AI1, an unconverted gas regulating valve HV1, and an unconverted gas flow meter FI1 are sequentially installed on the unconverted gas pipeline. The converted gas system from the cryogenic methanol washing unit is connected to the refined syngas main pipe via a converted gas pipeline. A converted gas analyzer AI2, a converted gas regulating valve HV2, and a converted gas flow meter FI2 are sequentially installed on the converted gas pipeline. A refined syngas flow meter FI3 and a refined syngas analyzer AI3 are sequentially installed on the refined syngas main pipe.

[0015] The outlet of the hydrogen purification unit is divided into two streams. One stream is connected to the compression and filling device through the product gas pipeline, and a product gas regulating valve HV3 is installed on the product gas pipeline. The other stream is connected to the refined syngas main pipeline through the recovery hydrogen pipeline, and a recovery hydrogen regulating valve HV4 and a recovery hydrogen flow meter FI4 are installed in sequence on the recovery hydrogen pipeline.

[0016] The unconverted gas analyzer AI1, unconverted gas flow meter FI1, converted gas analyzer AI2, converted gas flow meter FI2, refined syngas flow meter FI3, refined syngas analyzer AI3, and recovered hydrogen flow meter FI4 are connected to the calculator KY1 via cables. After calculation by the calculator KY1, the unconverted gas replenishment quantity FI5 signal and the converted gas replenishment quantity FI6 signal are output. The output signals are connected to the DCS operator station.

[0017] Furthermore, the unconverted gas analyzer AI1 is an online analyzer that simultaneously analyzes carbon monoxide content AI1-CO and hydrogen content AI1-H2.

[0018] Furthermore, the shift gas analyzer AI2 is an online analyzer that simultaneously analyzes carbon monoxide content AI2-CO and hydrogen content AI2-H2.

[0019] Furthermore, the refined syngas analyzer AI3 is an online analyzer that simultaneously analyzes carbon monoxide content AI3-CO and hydrogen content AI3-H2.

[0020] Furthermore, the unconverted gas regulating valve HV1, the converted gas regulating valve HV2, the product gas regulating valve HV3, and the recovered hydrogen regulating valve HV4 are online regulating valves, and the regulating valves are ball valves, butterfly valves, or shut-off valves.

[0021] A second aspect of the present invention provides a method for recovering hydrogen in a hydrogen recovery system, wherein the hydrogen-to-carbon ratio of the refined syngas is controlled within the range of 1.01-1.05, and the unconverted gas replenishment amount FI5 and the shifted gas replenishment amount FI6 are calculated by the following formula:

[0022] FI5=[(FT1*AI1-H2+FT2*AI2-H2+FT4) / 1.03-FT2*AI2-CO] / AI1-CO-FT1;

[0023] FI6=[1.03*(FT1*AI1-CO+FT2*AI2-CO)-(FT1*AI1-H2+FT4)] / AI2-H2-FT2;

[0024] In the formula, FI5 is the amount of unswitched gas replenishment, FI6 is the amount of shifted gas replenishment, FT1 is the flow rate displayed by the unswitched gas flow meter FI1, AI1-H2 is the hydrogen content displayed by the unswitched gas analyzer AI1, FT2 is the flow rate displayed by the shifted gas flow meter FI2, AI2-H2 is the hydrogen content displayed by the shifted gas analyzer AI2, FT4 is the flow rate displayed by the recovered hydrogen flow meter FI4, AI2-CO is the carbon monoxide content displayed by the shifted gas analyzer AI2, and AI1-CO is the carbon monoxide content displayed by the unswitched gas analyzer AI1.

[0025] The operator station displays the unchanged gas supply amount FI5 and the changed gas supply amount FI6, which can be positive or negative. The operator adjusts the unchanged gas control valve HV1 or the changed gas control valve HV2 until the displayed value of the unchanged gas supply amount FI5 or the changed gas supply amount FI6 is 0.

[0026] The advantages and positive effects of this invention are:

[0027] 1. When the hydrogen compression and filling device stops filling, the present invention introduces the hydrogen purified by the hydrogen purification device into the main synthesis gas pipe of the butanol and octanol unit, avoiding the loss of hydrogen due to hydrogen venting caused by the hydrogen purification device stopping or not stopping; it can ensure the continuous operation of the hydrogen purification device, avoid the fluctuation of upstream gas volume caused by start-up and shutdown, and avoid the pulverization of adsorbent, thus ensuring the stable operation of the upstream device and extending the service life of the adsorbent.

[0028] 2. This invention reduces the increase in venting losses caused by start-up and shutdown, reduces material losses, thereby reducing manufacturing costs and improving product competitiveness.

[0029] 3. This invention enables rapid supply and stable product quality even when downstream demand is insufficient or fluctuating, providing a solid guarantee for the use of downstream hydrogen refueling stations.

[0030] 4. This invention can intuitively display the amount of gas that needs to be increased or decreased through a calculator algorithm, which is convenient and quick, reduces the difficulty of operation for operators, and improves work efficiency.

[0031] 5. This invention, while recovering hydrogen, solves the problem of large fluctuations in the hydrogen-to-carbon ratio of the syngas main, ensuring stable production of the butanol and octanol unit. Attached Figure Description

[0032] Figure 1 Background technical solution: Hydrogen refueling mother station flow diagram;

[0033] Figure 2 Background technical solution: Refined syngas flow diagram;

[0034] Figure 3 Flowchart of an embodiment of this application;

[0035] Among them: 1-raw material gas pipeline, 2-product gas pipeline, 3-unchanged pipeline, 4-refined syngas main pipeline, 5-changed gas pipeline, 6-recovered hydrogen pipeline, AI1-unchanged gas analyzer, HV1-unchanged gas regulating valve, FI1-unchanged gas flow meter, AI2-changed gas analyzer, HV2-changed gas regulating valve, FI2-changed gas flow meter, FI3-refined syngas flow meter, AI3-refined syngas analyzer, HV4-recovered hydrogen regulating valve, FI4-recovered hydrogen flow meter, FI5-unchanged gas replenishment amount, FI6-changed gas replenishment amount. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] like Figure 3 The hydrogen recovery system of a hydrogen refueling mother station shown has the following configurations: The unconverted gas system is connected to the refined syngas main pipe 4 via unconverted gas pipeline 3. Unconverted gas analyzer AI1, unconverted gas regulating valve HV1, and unconverted gas flow meter FI1 are sequentially installed on unconverted gas pipeline 3. The converted gas system is connected to the refined syngas main pipe 4 via converted gas pipeline 5. Converted gas analyzer AI2, converted gas regulating valve HV2, and converted gas flow meter FI2 are sequentially installed on converted gas pipeline 5. Refined syngas flow meter FI3 and refined syngas analyzer AI3 are sequentially installed on the refined syngas main pipe 4. The hydrogen purification unit outlet is divided into two streams: one stream is connected to the compression and filling device via product gas pipeline 2, with product gas regulating valve HV3 installed on product gas pipeline 2; the other stream is connected to the refined syngas main pipe 4 via recovered hydrogen pipeline 6, with recovered hydrogen regulating valve HV4 and recovered hydrogen flow meter FI4 sequentially installed on recovered hydrogen pipeline 6. The unconverted gas analyzer AI1, unconverted gas flow meter FI1, converted gas analyzer AI2, converted gas flow meter FI2, refined syngas flow meter FI3, refined syngas analyzer AI3, and recovered hydrogen flow meter FI4 are connected to the calculator KY1 via cables. After calculation by the calculator KY1, the unconverted gas replenishment quantity FI5 signal and the converted gas replenishment quantity FI6 signal are output. The output signals are connected to the DCS operator station.

[0038] The unshifted gas analyzer AI1 is an online analyzer that simultaneously analyzes carbon monoxide (AI1-CO) and hydrogen (AI1-H2). The shifted gas analyzer AI2 is an online analyzer that simultaneously analyzes carbon monoxide (AI2-CO) and hydrogen (AI2-H2). The refined syngas analyzer AI3 is an online analyzer that simultaneously analyzes carbon monoxide (AI3-CO) and hydrogen (AI3-H2).

[0039] The unconverted gas regulating valve HV1, the converted gas regulating valve HV2, the product gas regulating valve HV3, and the recovered hydrogen regulating valve HV4 are online regulating valves, and the regulating valves are ball valves, butterfly valves, or shut-off valves.

[0040] The unchanged gas supply FI5 signal and the changed gas supply FI6 signal can be positive or negative. Positive values ​​require an increase in flow rate, while negative values ​​require a decrease in flow rate.

[0041] The hydrogen recovery system of the hydrogen refueling mother station operates on the following principle: the hydrogen-to-carbon ratio of the refined syngas is controlled within the range of 1.01-1.05. Taking a hydrogen-to-carbon ratio of 1.03 as an example, according to the material balance, (unprocessed hydrogen + processed hydrogen + recovered hydrogen) / (unprocessed carbon monoxide + processed carbon monoxide) = 1.03, that is: (FT1*AI1-H2 + FT2*AI2-H2 + FT4) / [(FT1 + FT5)*AI1-CO + FT2*AI2-CO] = 1.03 or [FT1*AI1-H2 + (FT2 + FT6)*AI2-H2 + FT4] / (FT1*AI1-CO + FT2*AI2-CO) = 1.03. Calculations using a calculator show that...

[0042] FI5=[(FT1*AI1-H2+FT2*AI2-H2+FT4) / 1.03-FT2*AI2-CO] / AI1-CO-FT1;

[0043] Or FI6 = [1.03*(FT1*AI1-CO+FT2*AI2-CO)-(FT1*AI1-H2+FT4)] / AI2-H2-FT2.

[0044] In the formula: FI5 is the amount of unswitched gas replenished, FI6 is the amount of shifted gas replenished, FT1 is the flow rate displayed by the unswitched gas flow meter FI1, AI1-H2 is the hydrogen content displayed by the unswitched gas analyzer AI1, FT2 is the flow rate displayed by the shifted gas flow meter FI2, AI2-H2 is the hydrogen content displayed by the shifted gas analyzer AI2, FT4 is the flow rate displayed by the recovered hydrogen flow meter FI4, AI2-CO is the carbon monoxide content displayed by the shifted gas analyzer AI2, and AI1-CO is the carbon monoxide content displayed by the unswitched gas analyzer AI1.

[0045] The operator station displays the unconverted gas replenishment amount FI5 and the converted gas replenishment amount FI6, which are either positive or negative. Positive values ​​require increasing the flow rate, while negative values ​​require decreasing the flow rate. The operator adjusts the unconverted gas regulating valve HV1 or the converted gas regulating valve HV2 until the displayed value of the unconverted gas replenishment amount FI5 or the converted gas replenishment amount FI6 is 0. This ensures a stable hydrogen-to-carbon ratio in the refined syngas main.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for hydrogen recovery at a hydrogen refueling mother station, characterized in that, The unconverted gas system from the low-temperature methanol washing unit is connected to the refined syngas main line via an unconverted gas pipeline. An unconverted gas analyzer AI1, an unconverted gas regulating valve HV1, and an unconverted gas flow meter FI1 are installed sequentially on the unconverted gas pipeline. The converted gas system from the low-temperature methanol washing unit is connected to the refined syngas main line via a converted gas pipeline. A converted gas analyzer AI2, a converted gas regulating valve HV2, and a converted gas flow meter FI2 are installed sequentially on the converted gas pipeline. A refined syngas flow meter FI3 and a refined syngas analyzer AI3 are installed sequentially on the refined syngas main line. The outlet of the hydrogen purification unit is divided into two streams. One stream is connected to the compression and filling device through the product gas pipeline, and a product gas regulating valve HV3 is installed on the product gas pipeline. The other stream is connected to the refined syngas main pipeline through the recovery hydrogen pipeline, and a recovery hydrogen regulating valve HV4 and a recovery hydrogen flow meter FI4 are installed in sequence on the recovery hydrogen pipeline. The unconverted gas analyzer AI1, unconverted gas flow meter FI1, converted gas analyzer AI2, converted gas flow meter FI2, refined syngas flow meter FI3, refined syngas analyzer AI3 and recovered hydrogen flow meter FI4 are connected to the calculator KY1 via cables. After calculation by the calculator KY1, the unconverted gas replenishment amount FI5 signal and the converted gas replenishment amount FI6 signal are output. The output signals are connected to the DCS operation station. The hydrogen-to-carbon ratio of the refined syngas is controlled within the range of 1.01-1.

05. The unswitched gas replenishment amount FI5 and the shifted gas replenishment amount FI6 are calculated using the following formula: FI5=[(FT1 AI1-H2+ FT2 AI2-H2+ FT4) / 1.03 - FT2 AI2-CO] / AI1-CO - FT1; FI6=[1.03 (FT1 AI1-CO + FT2 AI2-CO)-(FT1 AI1-H2+ FT4)] / AI2-H2- FT2; In the formula, FI5 is the amount of unswitched gas replenishment, FI6 is the amount of shifted gas replenishment, FT1 is the flow rate displayed by the unswitched gas flow meter FI1, AI1-H2 is the hydrogen content displayed by the unswitched gas analyzer AI1, FT2 is the flow rate displayed by the shifted gas flow meter FI2, AI2-H2 is the hydrogen content displayed by the shifted gas analyzer AI2, FT4 is the flow rate displayed by the recovered hydrogen flow meter FI4, AI2-CO is the carbon monoxide content displayed by the shifted gas analyzer AI2, and AI1-CO is the carbon monoxide content displayed by the unswitched gas analyzer AI1. The unchanged gas supply FI5 and changed gas supply FI6 are displayed on the operator station, and are either positive or negative. The operator adjusts the unchanged gas control valve HV1 or the changed gas control valve HV2 until the displayed value of the unchanged gas supply FI5 or the changed gas supply FI6 is 0. The unchanging gas analyzer AI1 is an online analyzer that simultaneously analyzes carbon monoxide content AI1-CO and hydrogen content AI1-H2; The shift gas analyzer AI2 is an online analyzer that simultaneously analyzes carbon monoxide content AI2-CO and hydrogen content AI2-H2. The refined syngas analyzer AI3 is an online analyzer that simultaneously analyzes carbon monoxide (AI3-CO) and hydrogen (AI3-H2).

2. The hydrogen recovery method for a hydrogen refueling mother station according to claim 1, characterized in that, The unchanging gas regulating valve HV1, changing gas regulating valve HV2, product gas regulating valve HV3, and recovered hydrogen regulating valve HV4 are online regulating valves, and the regulating valves are ball valves, butterfly valves, or shut-off valves.

Images