Double-raw-material adsorption hydrogen production method

Abstract

The invention relates to the technical field of adsorption hydrogen production, in particular to a double-raw-material adsorption hydrogen production method which comprises the steps of producing hydrogen by taking coke oven gas as a raw material and producing hydrogen by taking hydrogen-rich gas as a raw material. The method for producing hydrogen by taking coke oven gas as a raw material comprises the following steps: sequentially carrying out naphthalene removal, compression, pretreatment, pressure swing adsorption and purification on the coke oven gas to obtain hydrogen; the hydrogen production by taking the hydrogen-rich gas as the raw material comprises the following steps: sequentially performing a pressure swing adsorption process and a purification process on the hydrogen-rich gas in hydrogen production by taking the coke oven gas as the raw material to obtain hydrogen; when hydrogen production with coke oven gas as the raw material is interrupted, hydrogen production with hydrogen-rich gas as the raw material is switched to be executed, and when hydrogen production with hydrogen-rich gas as the raw material is interrupted, hydrogen production with coke oven gas as the raw material is switched to be executed. According to the invention, double-raw-material adsorption hydrogen production can be realized, the stability of adsorption hydrogen production can be ensured, and hydrogen with the purity being greater than or equal to 99.999% can be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production by adsorption, and in particular to a method for producing hydrogen by adsorption using two raw materials. Background Art

[0002] When the metallurgical industry produces cold-rolled sheets and galvanized sheets, hydrogen is used as the reducing protective gas in the bell-type annealing furnace or continuous annealing furnace. At present, the most widely used hydrogen production technologies at home and abroad include: methanol steam reforming hydrogen production technology, water electrolysis hydrogen production process, coke oven gas pressure swing adsorption hydrogen production technology, etc.

[0003] The basic principle of methanol steam reforming hydrogen production technology is to use methanol (CH3OH) and water vapor (H2O) to react chemically under the action of a catalyst to generate hydrogen (H2) and carbon dioxide (CO2). The reaction usually takes place between 200°C and 300°C, and copper-based catalysts and zinc-chromium catalysts are required to speed up the reaction. However, there is still room for improvement in terms of device operation stability, reliability, and safety.

[0004] The process of producing hydrogen by electrolysis of water is very mature in the operation of small units. Its principle is to immerse two electrodes (anode and cathode) in an electrolyte. When an external power supply applies voltage, water molecules lose electrons at the anode to undergo an oxidation reaction to generate oxygen; at the same time, they gain electrons at the cathode to undergo a reduction reaction to generate hydrogen. The operation of hydrogen production by electrolysis of water is reliable and flexible. In particular, the stepless pressure regulation technology developed in recent years allows the hydrogen pressure to be arbitrarily adjusted within the range of 0.05MPa-0.15MPa. However, the disadvantage of the process of producing hydrogen by electrolysis of water is its high power consumption (power consumption 4.5-5kWh / m 3 ), the purity of hydrogen is generally between 99.2% and 99.5%, and a hydrogen purification device is required.

[0005] In recent years, the coke oven gas temperature swing pressure swing adsorption hydrogen production device has become increasingly mature, and has gradually replaced the water electrolysis hydrogen production process in the cold rolling and stainless steel projects in the steel industry. Usually, the hydrogen production unit uses coke oven gas or natural gas as raw material to produce hydrogen. The compressed coke oven gas first passes through the temperature swing adsorption process to remove hydrocarbons above C5 and other high boiling point components to achieve the purpose of purifying the coke oven gas; then it passes through the pressure swing adsorption process to remove all impurity components except oxygen. Its biggest advantage is that the gas output is large and the energy consumption is relatively low (power consumption 0.4-0.5kWh / m 3 ). The biggest disadvantage of this process is that the coke oven gas needs to be pre-treated, that is, the industrial naphthalene in the coke oven gas needs to be removed by naphthalene removal before entering the adsorption tower, and H2S, tar, etc. need to be removed at the same time, otherwise it will cause blockage and poisoning of the adsorbent. Among them, there are about 12 pressure vessels in the naphthalene removal and other treatment processes, and the life of the adsorbent in this process is short; at the same time, the compression process needs to be equipped with 3-5 compressors and corresponding workshops, the compressor failure rate is high, and the corresponding seals need to be replaced about 15 days. Summary of the invention

[0006] Aiming at the technical problem that the high failure rate of compressor and frequent replacement of adsorbents in the pretreatment of coke oven gas before pressure swing adsorption hydrogen production affect the inability to provide a gas source for subsequent pressure swing adsorption hydrogen production, the present invention aims to provide a dual-raw material adsorption hydrogen production method to achieve dual-raw material hydrogen production and ensure the stability of adsorption hydrogen production.

[0007] The present invention provides a dual-raw material adsorption hydrogen production method, comprising hydrogen production using coke oven gas as a raw material and hydrogen production using hydrogen-rich gas as a raw material; hydrogen production using coke oven gas as a raw material comprises that the coke oven gas is sequentially subjected to a naphthalene removal process, a compression process, a pretreatment process, a pressure swing adsorption process, and a purification process to produce hydrogen; hydrogen production using hydrogen-rich gas as a raw material comprises that the hydrogen-rich gas is sequentially subjected to a pressure swing adsorption process and a purification process in hydrogen production using coke oven gas as a raw material to produce hydrogen; when hydrogen production using coke oven gas as a raw material is interrupted, switching to hydrogen production using hydrogen-rich gas as a raw material is executed, and when hydrogen production using hydrogen-rich gas as a raw material is interrupted, switching to hydrogen production using coke oven gas as a raw material.

[0008] Furthermore, the coke oven gas includes the following components in volume percentage: CO 6%~9%, CO2 2%~3%, CH4 20%~30%, H2 50%~60%, O2 0.8%~1.2%, O2 4%~7%, and the remainder is unsaturated hydrocarbons.

[0009] Furthermore, the hydrogen-rich gas includes the following components in volume percentage: H2 70%~95%, CH4 1%~20%, and the balance is nitrogen.

[0010] Furthermore, the pressure of the coke oven gas before the naphthalene removal process is 16 kPa, the temperature is ≤ 55 ° C, and the naphthalene content in the coke oven gas after the naphthalene removal process is < 10 mg / Nm 3 , tar content is 3~5mg / Nm 3 The naphthalene removal process is used to remove most of the naphthalene in coke oven gas.

[0011] Furthermore, the pressure of the coke oven gas after the naphthalene removal process is 8-10 kPa and the temperature is 40-60° C., and the pressure of the coke oven gas after the compression process is 1.78-1.85 MPa.G and the temperature is 30-40° C. After the compression process, the pressure of the coke oven gas is increased.

[0012] Furthermore, the pretreatment process includes adsorption oil removal, adsorption hydrocarbon removal and sulfur removal, and heating treatment in sequence. After the treatment, tar, H2S, alkanes and aromatics in the coke oven gas are removed.

[0013] Furthermore, the pressure swing adsorption process includes a plurality of pressure swing adsorption towers connected in parallel, each of which performs a pressure swing adsorption operation in sequence, and when one of the pressure swing adsorption towers performs a pressure swing adsorption operation, the other pressure swing adsorption towers perform an adsorbent desorption and regeneration operation.

[0014] Furthermore, the adsorbent desorption and regeneration operation includes the steps of equal pressure drop, forward placement, reverse placement, flushing, equal pressure increase, and final increase in sequence.

[0015] Furthermore, the purification process includes a deoxygenation step, which is carried out in a deoxygenation tower filled with a Ba catalyst. Under the catalytic action of the catalyst, oxygen and hydrogen react to generate water and remove oxygen.

[0016] Furthermore, the interruption of hydrogen production using coke oven gas as raw material includes the interruption of at least one of the processes of removing naphthalene, compression and pretreatment.

[0017] The beneficial effects of the present invention are as follows: the dual raw material adsorption hydrogen production method provided by the present invention realizes dual raw material hydrogen production by optimizing raw material gas compared with conventional coke oven gas adsorption hydrogen production. When hydrogen production using coke oven gas as raw material is interrupted due to compressor failure or replacement of pre-treatment adsorbent, the hydrogen-rich raw material is switched to enter the pressure swing adsorption process for hydrogen production. When hydrogen is produced using hydrogen-rich gas, the operating energy and material consumption are greatly reduced, equipment failure is reduced, and no hazardous wastes such as tar and naphthalene are generated. At the same time, when a hydrogen-rich gas source cannot be provided, a relatively stable supply of coke oven gas can be used to produce hydrogen to ensure that the product hydrogen can be stably supplied. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic process flow chart of a specific embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] Example 1 The raw gas of the present invention is: coke oven gas, pressure 16kPa, coke oven gas temperature ≤55°C, coke oven gas humidity is water saturation; hydrogen-rich gas, pressure 1.8MPa.G. The composition of coke oven gas and hydrogen-rich gas is shown in Table 1.

[0022] Table 1 Composition of coke oven gas and hydrogen-rich gas used in the present invention

[0023] Combination Figure 1 The present invention provides a dual-raw material adsorption hydrogen production method, which specifically includes: (1) Naphthalene removal process With coke oven gas as raw material, the pressure of coke oven gas (PG1) coming from the main gas pipeline is about 16kPa, and the temperature is ≤55℃. It enters the naphthalene removal device through a branch pipeline. The naphthalene removal device consists of a naphthalene removal adsorption tower T101A / T101B, a naphthalene removal regeneration gas heater E101, a naphthalene removal regeneration gas cooler E102 and a coke oven gas buffer tank V101. After coarse filtration, the coke oven gas enters T101A in an adsorption state (T101A and T101B, one is in an adsorption state, and the other is in a regeneration state. Here, it is temporarily considered that T101A is in an adsorption state). The naphthalene content of the coke oven gas after naphthalene removal treatment is <10mg / Nm 3 , tar content 3~5mg / Nm 3 At the same time, hydrocarbon impurities above C4 are removed. After completion, naphthalene-free coke oven gas (PG2) is obtained and enters V101 for use by the coke oven gas compressor.

[0024] The naphthalene removal regeneration gas uses the pre-treated desorbed gas from the pressure swing adsorption process. The naphthalene removal regeneration gas is heated by E101 to regenerate T101B, and after regeneration, it is switched to E102 cooling to cool T101B. After T101B is cooled, it waits to enter the adsorption state. The desorbed gas generated in the naphthalene removal process is sent to the coke oven gas main network outside the boundary for recycling.

[0025] (2) Compression process After the naphthalene removal process, PG2 performs the compression process. The compression process device is composed of coke oven gas compressors Y201 and Y202. PG2 has a pressure of 8~10kPa and a temperature of 40~60℃. It enters Y201 / Y202 and produces pressurized coke oven gas (PG3) after compression. The outlet pressure of PG3 is 1.78~1.85MPa.G and the temperature is 30~40℃. The present invention sets two compressors in parallel, and the gas processing capacity of a single compressor is 600Nm 3 / h, can be started simultaneously when necessary.

[0026] (3) Pretreatment process After the compression process, PG3 enters the pretreatment process. The pretreatment process device is mainly composed of oil removal tower T301A / T301B, pretreatment adsorption tower T302A / T302B and pretreatment regeneration gas heater E301. The pressure of PG3 is 1.78~1.85MPa.G, and the temperature is 30~40℃. It enters the pretreatment process and enters T301A in the adsorption step (T301A and T301B, one is in the adsorption state, and the other is in the regeneration state. Here, T301A is temporarily considered to be in the adsorption state) to remove the remaining engine oil and saturated water. Then it enters T302A in the adsorption step (T302A and T302B, one is in the adsorption state, and the other is in the regeneration state. Here, T302A is temporarily considered to be in the adsorption state) to remove alkanes, aromatics and sulfides. After the pretreatment process, the coke oven gas (PG4) has reached the air intake standard of the pressure swing adsorption process.

[0027] The pre-treated regeneration gas uses the desorbed gas from the pressure swing adsorption process, which is heated by E301 and then used for the regeneration of T302A / T302B.

[0028] (4) Pressure swing adsorption process The pressure swing adsorption process adopts a device consisting of five adsorption towers T401A / T401B / T401C / T401D / T401E, a downstream gas buffer tank V401, a desorption gas buffer tank V02 and a crude hydrogen buffer tank V403. The adsorption tower of the present invention can meet the needs of using coke oven gas and hydrogen-rich gas source as raw materials, and can independently produce high-purity hydrogen: PG4 (1.78MPa~1.85MPa) enters the pressure swing adsorption process; hydrogen-rich gas (PG5) from the main pipeline network also directly enters the pressure swing adsorption process, and these two gases are switched and used by switching pipelines.

[0029] The process of using coke oven gas as raw material includes: passing PG4 after the pretreatment process of step (4) into the adsorption tower to perform the pressure swing adsorption process. The pressure swing adsorption adopts the 5-1-3 PSA process, in which one adsorption tower is always in the feed adsorption state, and the other four towers are in the desorption regeneration state. The process consists of adsorption, pressure equalization and pressure reduction (including one pressure equalization, two pressure equalization, and three pressure equalization), forward release, reverse release, flushing, pressure equalization and pressure increase (including three pressure equalization, two pressure increase, and one pressure increase) and the final product pressure increase step. Five adsorption towers alternately perform the above adsorption and regeneration operations to achieve continuous separation and purification of the gas to produce crude hydrogen (PG6). The specific operation steps and process parameters of the pressure swing adsorption and the alternating adsorption order of each adsorption tower are shown in Table 2 and Table 3.

[0030] Table 2 Specific operating process parameters

[0031] Table 3 Alternating adsorption order of each adsorption tower

[0032] When the adsorbent is replaced in the naphthalene removal process in the aforementioned step (1) or the compressor blower fails in the step (2), the introduction of the coke oven gas raw material is stopped to replace the adsorbent or to repair the compressor blower, the hydrogen production using the coke oven gas as the raw material is interrupted, and at the same time, the hydrogen production using the hydrogen-rich gas as the raw material is switched to be executed, specifically, the hydrogen-rich gas (PG5) of the main pipeline network will directly enter the pressure swing adsorption process by switching the pipeline, and the pressure swing adsorption process in step (4) will be executed. When the adsorbent is replaced and the compressor blower is repaired, the hydrogen-rich gas is cut out by switching the pipeline, the hydrogen production using the coke oven gas as the raw material is interrupted, and the hydrogen production using the coke oven gas as the raw material is switched to be executed.

[0033] Crude hydrogen (PG6) is produced by the pressure swing adsorption process in step (4).

[0034] (5) Purification process The purification process consists of two parts: deoxygenation and dehydration. The device consists of a deoxygenation tower T501, a water separator V501, a drying tower T502A / T502B, a regeneration drying tower T503 and a hydrogen buffer tank V503A / V503B.

[0035] PG6 is a crude hydrogen containing a small amount of oxygen, which needs to enter T501 again. T501 contains Ba catalyst. Oxygen and hydrogen react under catalysis to generate water, and then cool to room temperature through a cooler. At this time, part of the trace saturation generated by the reaction precipitates, and after the water is removed by V501, it enters T502A (T502A and T502B, one is in an adsorption state, and the other is in a regeneration state. Here, T502A is temporarily considered to be in an adsorption state). After drying, the product hydrogen enters V503A and V503B. The product hydrogen pressure is about 1.7MPa.G. V503A and V503B are filled, and then the pressure is reduced to 0.6MPa.G through another pipeline and sent out of the boundary area. When the process section of the device is stopped, the gas in V503A and V503B is used to provide product hydrogen (PG7) to the back end.

[0036] The regeneration process of T502B includes two steps: heating regeneration and cooling. In the heating regeneration process, the regenerated hydrogen is first dried by T503, and then heated to 150℃ to 200℃ to flush and heat T502B, so that the adsorbent is heated and the moisture in it is desorbed. The desorbed gas enters T502A after cooling and liquid separation. In the cooling process, the regenerated hydrogen directly enters T502B, lowers the temperature of T502B to room temperature, and then is heated by the heater and goes to T503 to heat and dry the desiccant in T503, and then goes to T502A for drying after cooling and liquid separation.

[0037] The purity of the hydrogen product obtained in this embodiment is ≥99.999%, the hydrogen pressure of the product is ≥0.6MPa, the dew point of the hydrogen pressure of the product is <-65°C, and the hydrogen production capacity is 500Nm 3 / h.

[0038] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A dual-raw material adsorption hydrogen production method, characterized in that: The method includes hydrogen production using coke oven gas as raw material and hydrogen production using hydrogen-rich gas as raw material; hydrogen production using coke oven gas as raw material includes the coke oven gas being sequentially subjected to a naphthalene removal process, a compression process, a pretreatment process, a pressure swing adsorption process, and a purification process to produce hydrogen; hydrogen production using hydrogen-rich gas as raw material includes the hydrogen-rich gas being sequentially subjected to a pressure swing adsorption process and a purification process in hydrogen production using coke oven gas as raw material to produce hydrogen; when hydrogen production using coke oven gas as raw material is interrupted, hydrogen production using hydrogen-rich gas as raw material is switched to be executed; when hydrogen production using hydrogen-rich gas as raw material is interrupted, hydrogen production using coke oven gas as raw material is switched to be executed.

2. A dual raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: Coke oven gas includes the following components in volume percentage: CO 6%~9%, CO2 2%~3%, CH4 20%~30%, H2 50%~60%, O2 0.8%~1.2%, O24%~7%, and the remainder is unsaturated hydrocarbons.

3. A dual raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The hydrogen-rich gas includes the following components in volume percentage: H2 70%~95%, CH4 1%~20%, and the balance is nitrogen.

4. A dual-raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The pressure of coke oven gas before the naphthalene removal process is 16kPa, the temperature is ≤55℃, and the naphthalene content in the coke oven gas after the naphthalene removal process is <10mg / Nm 3 , tar content is 3~5mg / Nm 3 .

5. A dual raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The pressure of coke oven gas after the naphthalene removal process is 8~10kPa and the temperature is 40~60℃. The pressure of coke oven gas after the compression process is 1.78~1.85MPa.G and the temperature is 30~40℃.

6. A dual-raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The pretreatment process includes adsorption oil removal treatment, adsorption hydrocarbon and sulfur removal treatment, and heating treatment in sequence.

7. A dual-raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The pressure swing adsorption process includes a plurality of pressure swing adsorption towers connected in parallel, each of which performs a pressure swing adsorption operation in sequence. When one of the pressure swing adsorption towers performs a pressure swing adsorption operation, the other pressure swing adsorption towers perform an adsorbent desorption and regeneration operation.

8. A dual-raw material adsorption hydrogen production method as claimed in claim 7, characterized in that: The adsorbent desorption and regeneration operation includes the steps of equal pressure drop, forward placement, reverse placement, flushing, equal pressure increase, and final increase in sequence.

9. A dual raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The purification process includes a deoxygenation step, which is carried out in a deoxygenation tower filled with a Ba catalyst.

10. A dual-raw material adsorption hydrogen production method as claimed in claim 1, characterized in that: The interruption of hydrogen production using coke oven gas as raw material includes the interruption of at least one of the processes of removing naphthalene, compression and pretreatment.

Images