A methanol reforming hydrogen purification system comprising multi-stage heat exchange and a control method thereof

Abstract

The application discloses a methanol reforming hydrogen production purification system comprising multistage heat exchange and a control method thereof. Methanol water raw materials in a methanol water raw material unit are sent into a methanol reforming hydrogen production reactor after passing through a first heat exchanger tube, a second heat exchanger tube and a third heat exchanger tube; after reaction, the reforming gas is sent into a gas-liquid separator after passing through a third heat exchanger shell, a fourth heat exchanger and a first heat exchanger shell; the gas separated by the gas-liquid separator is discharged through a gas outlet and then sent into a PSA purification unit; the gas discharged by the PSA purification unit is sent into a carbon monoxide methanation unit through one path of a fifth heat exchanger; the gas discharged by the carbon monoxide methanation unit is sent to a hydrogen use end after passing through another path of the fifth heat exchanger and a second heat exchanger shell. The methanol reforming hydrogen production purification system has five heat exchangers, adopts a multistage heat exchange system to recycle and utilize waste heat of the whole system, fully utilizes heat, reduces heat waste and energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy methanol hydrogen production, and also relates to the application of multi-stage heat exchange in a methanol hydrogen production system, in particular to a methanol reforming hydrogen production and purification multi-stage heat exchange system, and more particularly to a methanol reforming hydrogen production and purification system comprising multi-stage heat exchange and a control method thereof. BACKGROUND

[0002] At present, in the field of hydrogen energy, there are methods for producing hydrogen, such as water electrolysis, methanol reforming, natural gas reforming, etc. Among them, methanol steam reforming is a main implementation way for distributed hydrogen production, which has many advantages such as mild reaction temperature (200-300℃), less impurity products (in addition to H2, only CO2 and a small amount of CO, CH4, etc.) and high hydrogen production rate, etc. It is one of the most feasible ways to transfer hydrogen energy from experimental research to industrial application.

[0003] In the existing methanol reforming technology, the methanol reforming reaction temperature is between 240-270℃, and heat is needed for the preheating process and the reforming process. The usual heating method is external electric heating band or self-heating of methanol raw materials. After the reforming reaction is completed, cooling and heat exchange are needed for the purified hydrogen gas through pressure swing adsorption. In the whole system from the reforming stage to the cooling process in the pressure swing adsorption purification stage, a large amount of heat is wasted and not effectively recycled.

[0004] Therefore, how to fully utilize the heat of the methanol reforming hydrogen production system is what people hope to solve.

[0005] In order to solve the above problems, the present application is proposed. SUMMARY

[0006] The first aspect of the present application provides a methanol reforming hydrogen production and purification system comprising multi-stage heat exchange, which comprises a methanol water raw material unit, a methanol steam reforming hydrogen production unit, a gas-liquid separator, a PSA purification unit and a carbon monoxide methanation unit.

[0007] The methanol steam reforming hydrogen production unit comprises a methanol reforming hydrogen production reactor, and the methanol reforming hydrogen production reactor comprises a methanol water raw material inlet and a reforming gas outlet.

[0008] The methanol water raw material in the methanol water raw material unit passes through the first heat exchanger tube, the second heat exchanger tube and the third heat exchanger tube, and then enters the methanol reforming hydrogen production reactor through the methanol water raw material inlet for reaction, and the generated reforming gas is discharged through the reforming gas outlet.

[0009] The reforming gas discharged from the reforming gas outlet enters the gas-liquid separator after passing through the third heat exchanger shell, the fourth heat exchanger and the first heat exchanger shell.

[0010] The liquid separated by the gas-liquid separator is discharged through a liquid outlet, and the gas separated is discharged through a gas outlet and then enters the PSA purification unit;

[0011] The gas discharged by the PSA purification unit enters the carbon monoxide methanation unit through one path of the fifth heat exchanger;

[0012] The gas discharged by the carbon monoxide methanation unit is transported to a hydrogen use end after being cooled in the other path of the fifth heat exchanger and the shell side of the second heat exchanger.

[0013] Preferably, the first heat exchanger is a double-pipe heat exchanger, the second heat exchanger is a sleeve heat exchanger, the third heat exchanger is a sleeve heat exchanger, the fourth heat exchanger is a wind-cooled heat exchanger, and the fifth heat exchanger is a plate heat exchanger.

[0014] The fourth heat exchanger is a wind-cooled heat exchanger, which can be used to cool the entire methanol reforming hydrogen purification system.

[0015] The methanol reforming hydrogen purification system has five heat exchangers, and a multi-stage heat exchange system is used to recycle and utilize the waste heat of the entire system, thereby fully utilizing the heat, reducing heat waste and energy consumption.

[0016] The methanol reforming hydrogen purification system can realize rapid restart during shutdown and power fluctuation, because the methanol water raw material is preheated by the third heat exchanger when the third heat exchanger is operated before the fluctuation working condition, when the methanol water raw material enters the methanol steam reforming hydrogen unit for reforming reaction, so that the methanol water entering the methanol reforming hydrogen reactor is preheated after the restart, thereby ensuring that the methanol reforming hydrogen reactor can be rapidly started. If the cold methanol water raw material is directly transported to the methanol reforming hydrogen reactor, the methanol reforming hydrogen reactor needs to be preheated for a period of time by the methanol fuel heating unit before it can be started.

[0017] Methanol reforming hydrogen is mainly applied to fuel cell power generation and other power generation, and the load is fluctuant. The current methanol hydrogen production technology cannot completely couple with the dynamic load, and the chemical reaction has hysteresis. The methanol reforming hydrogen purification system of the application can be applied to fluctuating load conditions.

[0018] Most of the current methanol reforming hydrogen devices are applied to chemical plants, which are large and inconvenient to move. Since the heat generated by the device has been recycled and utilized, only the fourth heat exchanger, i.e., the wind-cooled heat exchanger, is used for cooling, so that the operating temperature of each component of the system itself does not exceed 270 DEG C. After the heat is utilized by the multi-stage heat exchanger, the temperature of the output gas and liquid (waste liquid) is very low, so no additional water cooling unit is needed for cooling, and the device is suitable for island off-grid.

[0019] The PSA further eliminates impurities after recombination of methane, and the hydrogen purity is higher. In addition, the gas discharged from the PSA purification unit enters one path of the fifth heat exchanger, and exchanges heat with the gas discharged from the carbon monoxide methanation unit in the other path of the fifth heat exchanger. The gas discharged from the PSA purification unit is heated, while the gas discharged from the carbon monoxide methanation unit is cooled. The heat exchange between the PSA and the methanation unit not only increases the temperature of the gas entering the methanation unit, but also reduces the temperature of the gas discharged from the carbon monoxide methanation unit, thereby saving energy.

[0020] Preferably, the methanol reforming hydrogen production system further comprises a methanol combustion heating unit, and the methanol combustion heating unit comprises a preheating heating part and a reforming heating part.

[0021] The preheating heating part comprises a preheating fuel pump and a preheating air pump. The preheating fuel pump pumps out the methanol fuel in the methanol fuel tank, and the preheating air pump pumps in the external air to be mixed with the methanol fuel. The mixture is combusted to preheat the methanol reforming hydrogen production reactor.

[0022] The reforming heating part comprises a reforming fuel pump and a reforming air pump. The reforming fuel pump pumps out the methanol fuel in the methanol fuel tank, and the reforming air pump pumps in the external air to be mixed with the methanol fuel. The mixture is combusted to provide heat to the methanol reforming hydrogen production reactor for the methanol reforming hydrogen production reaction. That is, the methanol fuel combustion is used for preheating the reformer in the start-up stage, and is used for heating the reformer in the normal operation stage.

[0023] Preferably, the methanol combustion heating unit further comprises a nozzle. The methanol fuel pumped out by the preheating fuel pump and the reforming fuel pump is atomized by the nozzle and mixed with air. Currently, there are two ways for methanol hydrogen production technology, i.e. external electric heating and chemical reaction self-heating. In the self-heating technology, the commonly used method is the methanol combustion self-heating reaction, which requires external air and methanol fuel reaction. Currently, the methanol combustion heating unit adopts a methanol pump to pump in methanol and an air pump to pump in air. In the present application, the methanol fuel pumped out by the fuel pump is atomized by the nozzle and mixed with air. The function of this method is as follows: (1) the methanol is atomized by the nozzle and mixed with air, thereby increasing the contact area of the methanol and air catalytic oxidation reaction; and (2) the air delivered by the air pump can drive the atomized methanol, thereby reducing the energy consumption of the methanol pump.

[0024] Preferably, the PSA purification unit further comprises a product hydrogen delivery pipeline and a back-burning gas discharge pipeline. The product hydrogen in the product hydrogen tank enters the adsorption tower of the PSA purification unit through the product hydrogen delivery pipeline, and the washed gas is discharged as back-burning gas through the back-burning gas discharge pipeline into the methanol combustion heating unit for combustion to release heat. The product hydrogen delivery pipeline is provided with a flushing valve, and the back-burning gas discharge pipeline is provided with a back-burning inlet valve.

[0025] The present application further transports the product hydrogen in the product hydrogen tank to the adsorption tower of the PSA purification unit and flushes it, and the flushed gas is used as the back burning gas and enters the methanol combustion heating unit through the back burning gas discharge pipeline, is burned again to release heat, and further utilizes the heat of the product hydrogen.

[0026] Preferably, the back burning gas discharge pipeline further has a buffer tank, a product hydrogen removal pipe, a product hydrogen removal vent pipe, a product hydrogen removal inlet valve, and a back burning vent valve, the buffer tank is used to stabilize the back burning gas pressure, the product hydrogen removal pipe and the product hydrogen removal vent pipe directly discharge when the back burning gas pressure is too high, and the back burning gas is directly vented when the product hydrogen removal pipe flow is too large, so as to ensure the safety of the equipment.

[0027] Preferably, the PSA purification unit includes a plurality of adsorption towers, each of which has an independent gas inlet valve, an equalization / pressure increasing valve, Reverse flow valve and a gas inlet and outlet pipeline.

[0028] Preferably, the methanol water raw material unit further includes an inert gas delivery pipeline, the methanol water raw material delivery pipeline has a first manual regulating valve, the inert gas delivery pipeline has a second manual regulating valve, and the delivery of the methanol water raw material or the inert gas is realized through the adjustment of the first manual regulating valve and the second manual regulating valve. Specifically, when inert gas is delivered, the first manual regulating valve is closed and the second manual regulating valve is opened. When the equipment is normally operated, the first manual regulating valve is opened and the second manual regulating valve is closed. The delivery of the inert gas to the methanol reforming hydrogen production purification system has the following effects: (1) Before the start of the methanol reforming hydrogen production purification system, pressure test and leak detection can be performed, that is, inert gas is injected into the system, and the pressure value change of the pressure gauge is observed to determine the gas leakage of the system. Specifically, if the pressure value decreases, it also indicates that the system has a leakage point, and if the pressure value remains unchanged, it means that the system does not leak. (2) The inert gas delivered during the pressure test and leak detection before starting can remove the residual waste liquid in the methanol reforming reactor and the feed pipeline, achieving two purposes at once. (3) When the methanol reforming hydrogen production purification system is not used for a long time, inert gas can be delivered to the methanol reforming hydrogen production purification system to play a role in pressure replacement. On the one hand, the inert gas can avoid the influence of air on the service life of the catalyst and protect the catalyst, and on the other hand, it can also reduce the harm and influence of impurities generated by the methanol reforming hydrogen production purification system on the service life of the system.

[0029] Preferably, the inert gas is selected from nitrogen or argon.

[0030] Preferably, the methanol reforming hydrogen production system further includes a hydrogen removal device, which is located downstream of the PSA purification unit. The installation of the hydrogen removal device after the PSA desorption gas can make the device supply hydrogen indoors without danger.

[0031] Preferably, the methanol combustion heat supply unit further comprises a flow meter to control the flow of methanol fuel pumped by the preheating fuel pump and the reforming fuel pump.

[0032] Preferably, the methanol water raw material unit comprises a methanol water raw material tank and a methanol water raw material pump, and the methanol water raw material in the methanol water raw material tank is pumped into the first heat exchanger tube side by the methanol water raw material pump.

[0033] Preferably, Y-type filters are further arranged on the methanol water raw material output pipeline and the methanol fuel output pipeline, and the Y-type filters are used to filter solid particle impurities in the methanol water raw material or the methanol fuel to protect the normal operation of subsequent valves and equipment.

[0034] The methanol reforming hydrogen purification system of the present application comprises multiple stages of heat exchange, and during actual use, valves, pressure gauges and thermometers are arranged according to actual conditions.

[0035] The second aspect of the present application provides a control method of the methanol reforming hydrogen purification system of the first aspect of the present application, which comprises the following steps:

[0036] (1) The methanol water raw material enters the first heat exchanger tube side, exchanges heat with the reforming gas in the first heat exchanger shell side, the methanol water raw material is heated, and the reforming gas is cooled; the methanol water raw material absorbs heat of the reforming gas and is partially gasified, then the methanol water raw material enters the second heat exchanger tube side, exchanges heat with the gas discharged from the carbon monoxide methanation unit in the second heat exchanger shell side, the methanol water raw material is heated, and the gas discharged from the carbon monoxide methanation unit is cooled; then the methanol water raw material enters the third heat exchanger tube side, exchanges heat with the reforming gas in the third heat exchanger shell side, the methanol water raw material is heated, and the reforming gas is cooled; after three stages of heat exchange, the methanol water raw material enters the methanol water vapor reforming hydrogen production unit for reforming reaction;

[0037] (2) The reforming gas discharged from the reforming gas outlet is cooled by the third heat exchanger shell side, the fourth heat exchanger and the first heat exchanger shell side, and then enters the gas-liquid separator; the liquid separated by the gas-liquid separator is discharged through the liquid outlet, and the gas separated by the gas-liquid separator is discharged through the gas outlet and then enters the PSA purification unit;

[0038] (3) The gas discharged from the PSA purification unit enters one path of the fifth heat exchanger, exchanges heat with the gas discharged from the carbon monoxide methanation unit in another path of the fifth heat exchanger, the gas discharged from the PSA purification unit is heated, and the gas discharged from the carbon monoxide methanation unit is cooled;

[0039] (4) The carbon monoxide methanation unit discharges gas through another path of the fifth heat exchanger, and the second heat exchanger shell side is cooled, and then transported to the hydrogen use end;

[0040] The above steps are not distinguished in sequence, and are selected according to actual conditions.

[0041] Preferably, the product hydrogen in the product hydrogen tank is transported into the PSA purification unit, the gas after flushing is transported into the methanol combustion heating unit as the back-burning gas, and heat is released by burning again.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] 1、The methanol reforming hydrogen purification system has five heat exchangers, a multistage heat exchange system is used to recycle and utilize the waste heat of the whole system, heat is fully utilized, and heat waste and energy consumption are reduced.

[0044] 2、The methanol reforming hydrogen purification system can realize quick restart during shutdown and power fluctuation, because the methanol water raw material is preheated by the third heat exchanger when the third heat exchanger is operated before the fluctuation working condition generates after the methanol water raw material is subjected to three-stage heat exchange and then enters the methanol steam reforming hydrogen production unit to perform a reforming reaction, so that the methanol water entering the methanol reforming hydrogen reactor after restart is preheated, thereby ensuring that the methanol reforming hydrogen reactor can be quickly started. If the cold methanol water raw material is directly transported to the methanol reforming hydrogen reactor, the methanol reforming hydrogen reactor needs to be preheated for a period of time by the methanol fuel heating unit before the methanol reforming hydrogen reactor can be started.

[0045] The methanol reforming hydrogen is mainly applied to fuel cell power generation and other power generation, and the load is fluctuant. The current methanol hydrogen production technology cannot completely couple the dynamic load due to the hysteresis of the chemical reaction. The methanol reforming hydrogen purification system fully utilizes the heat of the methanol water raw material for preheating, can realize quick restart during shutdown and power fluctuation, and is thus suitable for fluctuation working condition load.

[0046] 3、At present, most of the methanol reforming hydrogen devices are applied to chemical plants, which are large and inconvenient to move. Since the heat generated by the device has been recycled and utilized, only the fourth heat exchanger, i.e., the air-cooled heat exchanger, is used for cooling, so that the operating temperature of each component of the system itself can be ensured to be not more than 270 DEG C. After the heat is utilized by the multistage heat exchanger, the temperature of the output gas and liquid (waste liquid) is very low, so that an additional water cooling unit is not needed for cooling, and the device is suitable for island off-grid.

[0047] 4. In this invention, the PSA is followed by methanation to further eliminate impurities, resulting in high hydrogen purity. Furthermore, the gas discharged from the PSA purification unit enters one path of the fifth heat exchanger and exchanges heat with the gas discharged from the carbon monoxide methanation unit in the other path of the fifth heat exchanger. The gas discharged from the PSA purification unit heats up, while the gas discharged from the carbon monoxide methanation unit cools down. Utilizing the heat exchange during the PSA-to-methanation stage, the temperature of the gas entering the methanation unit is increased, while the temperature of the gas discharged from the carbon monoxide methanation unit is decreased, thus saving energy.

[0048] 5. The methanol reforming hydrogen production system of the present invention also includes a methanol combustion heating unit. During the start-up phase, methanol fuel combustion is used to preheat the reformer, and during normal operation, it provides heat to the reformer. Furthermore, the methanol combustion heating unit also includes a nozzle. Currently, methanol hydrogen production technology has two methods: external electric heating and chemical reaction self-heating. Among them, the most commonly used self-heating technology is the methanol combustion self-heating reaction, which requires external air and methanol fuel to react. Currently, methanol combustion heating units all use a methanol pump to pump in methanol and an air pump to pump in air. In the present invention, the methanol fuel pumped out by the fuel pump is atomized by the nozzle and mixed with air. The function of this method is: (1) Using the nozzle to atomize methanol and mix it with air increases the contact area of ​​the catalytic oxidation reaction between methanol and air. (2) The air delivered by the air pump can carry the atomized methanol, thereby reducing the energy consumption of the methanol pump.

[0049] 6. In this invention, the product hydrogen in the product hydrogen tank is transported to the adsorption tower of the PSA purification unit and rinsed. The rinsed gas is used as burn-back gas and enters the methanol combustion heating unit through the burn-back gas discharge pipeline, where it is burned again to release heat, thus further utilizing the heat of the product hydrogen.

[0050] 7. The methanol-water raw material unit of the present invention also includes an inert gas conveying pipeline. The purpose of conveying inert gas to the methanol reforming hydrogen purification system is as follows: (1) Before starting the methanol reforming hydrogen purification system, a pressure test and leak detection can be performed, that is, inert gas is injected into the system, and the system leak can be judged by observing the pressure change of the pressure gauge. Specifically, if the pressure value drops, it indicates that there is a leak in the system. If the pressure value remains unchanged, it indicates that the system does not leak. (2) The inert gas introduced during the pressure test and leak detection before startup can remove the residual waste liquid in the methanol reforming reactor and feed pipeline, achieving two goals at once. (3) When the methanol reforming hydrogen purification system is not used for a long time, inert gas can be introduced into the methanol reforming hydrogen purification system to play the role of pressure maintenance and replacement. The introduced inert gas can prevent air from affecting the catalyst life and protect the catalyst. On the other hand, it can also reduce the harm and impact of impurities generated by the methanol reforming hydrogen purification system on the system life.

[0051] 8、The present application is provided with a hydrogen removal device after PSA analysis gas, which can supply hydrogen in the room without danger.

[0052] 9、According to the calculation, 10Nm 3 Under the working condition, the heat exchanger recovers heat load of 3039.5W. The multi-stage heat exchange system recycles waste heat of the whole system, fully utilizes heat, and realizes hydrogen production range of 0-20Nm 3 / h, and has high comprehensive energy utilization rate. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is a multi-stage heat exchange system for hydrogen production by methanol reforming of the present application;

[0054] Figure 2 It is a control method flow chart of the multi-stage heat exchange system for hydrogen production by methanol reforming of the present application. DETAILED DESCRIPTION

[0055] Those skilled in the art will appreciate that the following examples are intended to illustrate but not limit the scope of the present application. In the examples, the specific techniques or conditions not mentioned are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials or equipment not mentioned are all conventional products that can be obtained by purchase.

[0056] Those skilled in the art will appreciate that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should be further understood that the terms "comprise," "comprises," "comprising," "include," "includes," "including," "contain," "contains," "containing," where used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. In addition, the word "connected" as used herein can include wireless connection.

[0057] In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified. The orientation or state relationship indicated by the terms "inner", "upper", "lower", and the like is based on the orientation or state relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0058] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "provided with" should be understood in a broad sense, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application should be understood according to the specific circumstances.

[0059] Those skilled in the art can understand that, unless otherwise defined, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined.

[0060] Embodiment

[0061] As Figure 1 , the present embodiment is a methanol reforming hydrogen purification system comprising multi-stage heat exchange, which includes a methanol water raw material unit, a methanol steam reforming hydrogen production unit, a gas-liquid separator, a PSA purification unit and a carbon monoxide methanation unit;

[0062] The methanol steam reforming hydrogen production unit includes a methanol reforming hydrogen production reactor, which includes a methanol water raw material inlet and a reforming gas outlet;

[0063] The methanol water raw material in the methanol water raw material unit is reacted in the methanol reforming hydrogen production reactor through the first heat exchanger C101 tube, the second heat exchanger C103 tube and the third heat exchanger C102 tube after entering the methanol water raw material inlet, and the generated reforming gas is discharged through the reforming gas outlet;

[0064] The reforming gas discharged from the reforming gas outlet enters the gas-liquid separator C104 after passing through the third heat exchanger C102 shell, the fourth heat exchanger cooling air pump B102 and the first heat exchanger C101 shell;

[0065] The liquid separated by the gas-liquid separator C104 is discharged through the liquid outlet, and the gas separated is discharged through the gas outlet and then enters the PSA purification unit;

[0066] The gas discharged from the PSA purification unit enters the carbon monoxide methanation unit after passing through one path of the fifth heat exchanger plate heat exchanger;

[0067] The gas discharged from the carbon monoxide methanation unit is transported to the hydrogen use end after passing through the other path of the fifth heat exchanger plate heat exchanger and the second heat exchanger C103 shell cooling.

[0068] The first heat exchanger is a double-pipe heat exchanger C101, the second heat exchanger is a sleeve heat exchanger C103, the third heat exchanger is a sleeve heat exchanger C102, the fourth heat exchanger is an air-cooled heat exchanger B102, and the fifth heat exchanger is a plate heat exchanger.

[0069] The methanol reforming hydrogen purification system has five heat exchangers, and a multistage heat exchange system is used to recycle and utilize the waste heat of the whole system, so that the heat is fully utilized, the heat waste and energy consumption are reduced.

[0070] The methanol reforming hydrogen purification system can realize quick restart during shutdown and power fluctuation, because the methanol water raw material is preheated by the third heat exchanger when the front heat engine is running under fluctuating working conditions after the three-stage heat exchange, so that the methanol water raw material is preheated when entering the methanol reforming hydrogen reactor after the restart, thereby ensuring that the methanol reforming hydrogen reactor can be quickly started.

[0071] The methanol reforming hydrogen is mainly applied to fuel cell power generation and other power generation, and the load is fluctuant, and the current methanol hydrogen production technology cannot completely couple the dynamic load, and the chemical reaction has hysteresis, so that the methanol reforming hydrogen purification system can be applied to fluctuating load.

[0072] Most of the current methanol reforming hydrogen devices are applied to chemical plants, and are large and inconvenient to move, and the device recycles and utilizes the generated heat, only uses the fourth heat exchanger, i.e., an air-cooled heat exchanger for cooling, does not need external water cooling unit for cooling, and is suitable for island off-grid.

[0073] The PSA is further combined with methanation to eliminate impurities, and the hydrogen purity is higher. In addition, the gas discharged from the PSA purification unit enters the fifth heat exchanger in one path, and exchanges heat with the gas discharged from the carbon monoxide methanation unit in the other path of the fifth heat exchanger, so that the gas discharged from the PSA purification unit is heated, and the gas discharged from the carbon monoxide methanation unit is cooled, and the heat exchange of the PSA into the methanation one stage is utilized, which not only increases the temperature of the gas entering the methanation, but also reduces the temperature of the gas discharged from the carbon monoxide methanation unit, thereby saving energy.

[0074] The methanol reforming hydrogen system further comprises a methanol combustion heating unit, and the methanol combustion heating unit comprises a preheating heating part and a reforming heating part.

[0075] The preheating heat supply part comprises a preheating fuel pump P101a and a preheating air pump B101a, the preheating fuel pump P101a pumps out the methanol fuel in the methanol fuel tank, the preheating air pump B101a pumps in the ambient air to be mixed with the methanol fuel, and the mixed fuel is combusted to preheat the methanol reforming hydrogen production reactor;

[0076] The reforming heat supply part comprises a reforming fuel pump P101b and a reforming air pump B101b, the reforming fuel pump P101b pumps out the methanol fuel in the methanol fuel tank, the reforming air pump B101b pumps in the ambient air to be mixed with the methanol fuel, and the mixed fuel is combusted to provide heat for the methanol reforming hydrogen production reactor for the methanol reforming hydrogen production reaction.

[0077] The methanol combustion heat supply unit further comprises a nozzle, and the methanol fuel pumped out by the preheating fuel pump and the reforming fuel pump is atomized by the nozzle and mixed with air.

[0078] The PSA purification unit further comprises a product hydrogen delivery pipeline and a back-burning gas discharge pipeline, the product hydrogen in the product hydrogen tank is delivered into the adsorption tower of the PSA purification unit through the product hydrogen delivery pipeline, the flushed gas is used as back-burning gas and is discharged into the methanol combustion heat supply unit through the back-burning gas discharge pipeline, and the back-burning gas is combusted again to release heat.

[0079] The product hydrogen in the product hydrogen tank is delivered into the adsorption tower of the PSA purification unit, and the flushed gas is used as back-burning gas and is discharged into the methanol combustion heat supply unit through the back-burning gas discharge pipeline, and the back-burning gas is combusted again to release heat.

[0080] The burnout gas discharge pipeline also includes a buffer tank, a hydrogen removal pipe, a vent pipe, a hydrogen removal inlet valve KV107a-c, and a burnout vent valve KV108. The buffer tank is used to stabilize the burnout gas pressure. The hydrogen removal pipe and the vent pipe discharge directly when the burnout gas pressure is too high. When the flow rate of the hydrogen removal pipe is too large, the burnout gas is directly vented to ensure equipment safety.

[0081] The PSA purification unit includes multiple adsorption towers, each with an independent inlet valve KV101a-d, a pressure equalization / boosting valve KV105a-d, a backflow valve KV102a-d, and inlet and outlet pipelines.

[0082] The methanol-water feedstock unit also includes an inert gas delivery pipeline. The methanol-water feedstock delivery pipeline has a first manual regulating valve QV101, and the inert gas delivery pipeline has a second manual regulating valve QV102. The delivery of either the methanol-water feedstock or the inert gas is achieved by adjusting the first manual regulating valve QV101 and the second manual regulating valve QV102. Specifically, when inert gas is introduced, the first manual regulating valve QV101 is closed, and the second manual regulating valve QV102 is opened. During normal operation, the first manual regulating valve QV101 is opened, and the second manual regulating valve QV102 is closed. The purpose of supplying inert gas to the methanol reforming hydrogen purification system is: 1. Before starting the methanol reforming hydrogen purification system, a pressure test and leak detection can be performed, i.e., inert gas is introduced into the system, and the pressure gauge readings are observed to determine the system's leakage status. Specifically, a decrease in pressure indicates a leak, while a constant pressure indicates no leaks. 2. The inert gas introduced during the pressure test and leak detection before startup effectively removes residual waste liquid from the methanol reforming reactor and feed pipeline, achieving two goals at once. 3. When the methanol reforming hydrogen purification system is not used for an extended period, inert gas can be introduced to maintain pressure and facilitate purging. The introduced inert gas prevents air from affecting catalyst life and protects the catalyst; it also reduces the harmful effects of impurities generated by the methanol reforming hydrogen purification system on the system's lifespan. Nitrogen is selected as the inert gas.

[0083] The methanol reforming hydrogen production system also includes a hydrogen removal device, which is located downstream of the PSA purification unit. The hydrogen removal process of the device is as follows: Figure 1 As shown in the upper right corner, the gas from the "hydrogen elimination pipe" mixes with the air from the flue gas compressor B101c and enters the hydrogen elimination pipe. The hydrogen elimination pipe is filled with a catalyst (for the reaction of hydrogen and oxygen) to eliminate hydrogen and other combustible gases. The gas passing through the hydrogen elimination pipe is then discharged into the outside atmosphere. This invention adds a hydrogen elimination device after the PSA desorption gas, allowing the device to supply hydrogen indoors without causing danger.

[0084] The methanol combustion heating unit also comprises flow meters FG101a-b to control the flow of methanol fuel pumped by the preheating fuel pump P101a and the reforming fuel pump P101b.

[0085] The methanol water raw material unit comprises a methanol water raw material tank and a methanol water raw material pump, and the methanol water raw material in the methanol water raw material tank is pumped into the first heat exchanger C101 tube side by the methanol water raw material pump P102.

[0086] Y-type filters are further arranged on the methanol water raw material output pipeline and the methanol fuel output pipeline, which are used to filter solid particle impurities in the methanol water raw material or the methanol fuel, so as to protect the normal operation of the subsequent valves and equipment.

[0087] The methanol reforming hydrogen purification system comprises multiple stages of heat exchange, and valves, pressure gauges and thermometers are arranged according to actual conditions during actual use.

[0088] The control method of the methanol reforming hydrogen purification system comprises the following steps:

[0089] (1) The methanol water raw material enters the first heat exchanger C101 tube side, exchanges heat with the reforming gas in the first heat exchanger C101 shell side, the methanol water raw material is heated, and the reforming gas is cooled; the methanol water raw material absorbs heat of the reforming gas and is partially gasified, then enters the second heat exchanger C103 tube side, and exchanges heat with the gas discharged by the carbon monoxide methanation unit in the second heat exchanger C103 shell side, the methanol water raw material is heated, and the gas discharged by the carbon monoxide methanation unit is cooled; then the methanol water raw material enters the third heat exchanger C102 tube side, and exchanges heat with the reforming gas in the third heat exchanger C102 shell side, the methanol water raw material is heated, and the reforming gas is cooled; after three-stage heat exchange, the methanol water raw material enters the methanol water vapor reforming hydrogen production unit for reforming reaction;

[0090] (2) The reforming gas discharged by the reforming gas outlet is cooled by the third heat exchanger C102 shell side, the fourth heat exchanger cooling air pump B102 and the first heat exchanger C101 shell side, and then enters the gas-liquid separator C104; the liquid obtained by the gas-liquid separator C104 is discharged through the liquid outlet, and the gas obtained by separation is discharged through the gas outlet and then enters the PSA purification unit;

[0091] (3) The gas discharged by the PSA purification unit enters one path of the fifth heat exchanger plate heat exchanger, and exchanges heat with the gas discharged by the carbon monoxide methanation unit in the other path of the fifth heat exchanger plate heat exchanger, the gas discharged by the PSA purification unit is heated, and the gas discharged by the carbon monoxide methanation unit is cooled;

[0092] (4) The carbon monoxide methanation unit exhaust gas is transported to the hydrogen use end after being cooled in the shell side of the second heat exchanger C103 through another path of the fifth heat exchanger plate heat exchanger;

[0093] The above steps are not distinguished in sequence, and are selected according to actual conditions.

[0094] The product hydrogen in the product hydrogen tank is transported into the PSA purification unit, and the gas after flushing is transported into the methanol combustion heating unit as the back-burning gas to release heat by burning again.

[0095] As Figure 2 The specific control steps are as follows:

[0096] The hydrogen production switch is opened to start hydrogen production. Whether the temperatures of the methanol combustion preheating zone and the methanol reforming zone in the reactor are greater than 10℃ is judged according to the preheating zone temperature TI101a and the reforming zone temperature TI101b. If not, the reactor is heated by opening the electric heater EH101. After the temperature is greater than 10℃, the methanol raw material preheating air pump B101A and the reforming preheating air pump B101B are opened, the fuel pump P101A of the preheating zone and the fuel pump P101B of the reforming zone are opened, and the air carrying the methanol fuel is punched into the fuel reaction zone. At this time, the methanol fuel is preheated, and the chemical reaction is:

[0097] 2CH3OH+3O2=2CO2+4H2O

[0098] After the preheating zone and the reforming zone reach 238℃, the external cooling fan B102 is opened to cool the reaction temperature. At this time, the methanol combustion heating unit is still providing heat, and the fan is opened to prevent the temperature from rising rapidly (rapid temperature rise will cause the performance of the catalyst in the reactor to decrease). After the temperature is stabilized to 240℃, the methanol raw material feeding pump P102 is opened. The methanol raw material is first fed through the jacket heat exchanger C101, and is exchanged with the hydrogen-rich gas after the first stage heat exchange from the reforming reaction. The raw material gas is partially gasified after being heated, enters the upper layer of the reactor first stage C102 hydrogen-rich heat exchanger, and the lower layer is the methanation heat exchange from the jacket heat exchanger C103. After three-stage heat exchange, the hydrogen-rich gas after reforming enters the reactor to carry out the reforming reaction. The hydrogen-rich gas after reforming contains hydrogen, methane, carbon monoxide, etc., and the chemical reaction is:

[0099]

[0100]

[0101] The hydrogen-rich gas, after two-stage heat exchange with the methanol raw liquid, enters a gas-liquid separation tank C104, and the waste liquid is discharged after a certain volume. When the back pressure of the gas-liquid separation tank is 0.4-0.5 MPa and the temperature is 40-50℃, the PSA inlet valves KV101A, KV101B, KV101C and KV101D are opened in turn, and the PSA enters the equalization, adsorption, reverse discharge and flushing processes. In the reverse discharge process, part of the gas participates in the back burning of the methanol fuel, and part of the gas is used for hydrogen consumption. The purified purge gas enters a buffer tank for use. The upper limit of the pressure of the device is 0.9 MPa, and when the pressure exceeds the limit, the gas is automatically discharged through the vent pipe. The PSA rear end exchanges heat with the methanation gas through a plate heat exchanger and enters the methanation reaction, further purifying the hydrogen. The hydrogen, after heat exchange through the plate heat exchanger and the second-stage heat exchanger C103, enters the product gas outlet and the hydrogen tank. At this time, the purity of the gas is 99.99%.

[0102] The heat load recovered in the device is the sum of the heat loads of the five heat exchangers. The calculation method of the heat load of a single heat exchanger is as follows:

[0103] dtin(i,j)=Tin(i,j)-tout(i,j)

[0104] dtout(i,j)=Tout(i,j)-tin(i,j)

[0105] Q(i,j)=M(i,j)·(Hin(i,j)-Hout(i,j))=m(i,j)·Cp m (i,j)·(tout(i,j)-tin(i,j))

[0106] Tin, Tout represent the temperatures of the hot stream entering and leaving the heat exchanger; tin, tout represent the initial temperature and the temperature after heat exchange of the cold stream; Q represents the heat load of the heat exchanger, Watt; i, j represent the hot stream and the cold stream medium; M, m represent the mass flow rate of the hot stream and the cold stream, kg / s; Hin, Hout represent the specific enthalpy of the hot stream, J / kg; Cp m represents the specific heat capacity of the cold stream.

[0107] The present application obtains the inlet and outlet temperatures and compositions of each heat exchanger, calls the thermodynamic properties of each substance in the Coolprop thermodynamic database (open source thermodynamic database), calculates the changes of the thermodynamic properties of each substance at the inlet and outlet, and thereby obtains the heat load value recovered by each heat exchanger.

[0108] Take the first heat exchanger as an example for calculation: the first heat exchanger tube fluid is methanol water solution (import temperature 25℃, export temperature 74.28℃, mass flow 10.72kg / h, mass fraction: methanol 54%, water 46%), shell fluid is the reforming gas cooled by air-cooled heat exchanger (import temperature 94℃, export temperature 40℃, mass flow 10.72kg / h, mass fraction: methanol 0%, water 17.1%, carbon monoxide 2.3%, carbon dioxide 70.5%). Specific enthalpy and specific heat capacity are obtained from coolprop database (open source thermodynamic database) according to the temperature and pressure of the substance. The first heat exchanger heat load is 579.5W calculated according to the above formula.

[0109] The rest of the heat exchanger heat load calculation method is as above. Table 1 below lists the temperature and concentration composition of each heat exchanger import and export.

[0110] Table 1 Temperature and concentration composition of import and export of different heat exchangers

[0111]

[0112] According to the above calculation, the heat exchanger heat load of the present application is 3039.5W under the working condition of 10Nm 3 The above has made an exemplary description of the present application, it should be indicated that, without departing from the core of the present application, any simple deformation, modification or other equivalent replacement which can not cost the creative labor of the person skilled in the art falls into the protection scope of the present application.

Claims

1. A methanol reforming hydrogen purification system comprising multiple stages of heat exchange, characterized in that, It comprises a methanol water raw material unit, a methanol water steam reforming hydrogen production unit, a gas-liquid separator, a PSA purification unit and a carbon monoxide methanation unit; The methanol water steam reforming hydrogen production unit comprises a methanol reforming hydrogen production reactor, which comprises a methanol water raw material inlet and a reforming gas outlet; The methanol water raw material in the methanol water raw material unit enters the methanol reforming hydrogen production reactor through the first heat exchanger tube, the second heat exchanger tube and the third heat exchanger tube after the three-stage heat exchange, and the produced reforming gas is discharged through the reforming gas outlet; The reforming gas discharged through the reforming gas outlet enters the gas-liquid separator after the three-stage heat exchange of the third heat exchanger shell, the fourth heat exchanger and the first heat exchanger shell; The liquid separated by the gas-liquid separator is discharged through the liquid outlet, and the gas separated by the gas-liquid separator is discharged through the gas outlet and then enters the PSA purification unit; The gas discharged by the PSA purification unit enters the carbon monoxide methanation unit through one path of the fifth heat exchanger; The gas discharged by the carbon monoxide methanation unit is transported to the hydrogen use end after the two-stage heat exchange of the other path of the fifth heat exchanger and the second heat exchanger shell; The control method of the methanol reforming hydrogen purification system comprises the following steps: (1) The methanol water raw material enters the first heat exchanger tube, exchanges heat with the reforming gas in the first heat exchanger shell, the methanol water raw material is heated, and the reforming gas is cooled; then the methanol water raw material enters the second heat exchanger tube, exchanges heat with the gas discharged by the carbon monoxide methanation unit in the second heat exchanger shell, the methanol water raw material is heated, and the gas discharged by the carbon monoxide methanation unit is cooled; then the methanol water raw material enters the third heat exchanger tube, exchanges heat with the reforming gas in the third heat exchanger shell, the methanol water raw material is heated, and the reforming gas is cooled; The methanol water raw material enters the methanol water steam reforming hydrogen production unit after the three-stage heat exchange; (2) The reforming gas discharged through the reforming gas outlet enters the gas-liquid separator after the three-stage heat exchange of the third heat exchanger shell, the fourth heat exchanger and the first heat exchanger shell; (3) The gas discharged by the PSA purification unit enters the fifth heat exchanger through one path, exchanges heat with the gas discharged by the carbon monoxide methanation unit in the other path of the fifth heat exchanger, the gas discharged by the PSA purification unit is heated, and the gas discharged by the carbon monoxide methanation unit is cooled; (4) The gas discharged by the carbon monoxide methanation unit is transported to the hydrogen use end after the two-stage heat exchange of the other path of the fifth heat exchanger and the second heat exchanger shell; The above steps do not distinguish the sequence; The methanol reforming hydrogen purification system can realize quick restart during shutdown and power fluctuation; The methanol reforming hydrogen purification system does not need to connect an additional water cooling unit for cooling, and is suitable for island off-grid.

2. The methanol reforming hydrogen purification system of claim 1, wherein, The first heat exchanger is a double-pipe heat exchanger, the second heat exchanger is a sleeve heat exchanger, the third heat exchanger is a sleeve heat exchanger, the fourth heat exchanger is a air-cooled heat exchanger, and the fifth heat exchanger is a plate heat exchanger.

3. The methanol reforming hydrogen purification system of claim 1, wherein, The methanol reforming hydrogen purification system further comprises a methanol combustion heating unit, which comprises a preheating heating part and a reforming heating part. The preheating heating part comprises a preheating fuel pump and a preheating air pump, the preheating fuel pump pumps out the methanol fuel in a methanol fuel tank, and the preheating air pump pumps in ambient air to be mixed with the methanol fuel, and the mixture is combusted to preheat the methanol reforming hydrogen reactor. The reforming heating part comprises a reforming fuel pump and a reforming air pump, the reforming fuel pump pumps out the methanol fuel in a methanol fuel tank, and the reforming air pump pumps in ambient air to be mixed with the methanol fuel, and the mixture is combusted to provide heat to the methanol reforming hydrogen reactor for the methanol reforming hydrogen reaction.

4. The methanol reforming hydrogen purification system of claim 3, wherein, The methanol combustion heating unit further comprises a nozzle, and the methanol fuel pumped out by the preheating fuel pump and the reforming fuel pump is atomized by the nozzle and mixed with air.

5. The methanol reforming hydrogen purification system of claim 3, wherein, The PSA purification unit further comprises a product hydrogen delivery pipeline and a back-burning gas discharge pipeline, the product hydrogen in a product hydrogen tank is delivered into the PSA purification unit through the product hydrogen delivery pipeline, and the flushed gas is discharged into the methanol combustion heating unit as back-burning gas to be combusted again to release heat.

6. The methanol reforming hydrogen purification system of claim 1, wherein, The PSA purification unit comprises a plurality of adsorption towers, each of which has an independent inlet valve, an equalization / pressure increasing valve, a reverse discharge valve, and an inlet and outlet pipeline.

7. The methanol reforming hydrogen purification system of claim 1, wherein, The methanol water raw material unit further comprises an inert gas delivery pipeline, the methanol water raw material delivery pipeline is provided with a first manual regulating valve, and the inert gas delivery pipeline is provided with a second manual regulating valve, and the delivery of the methanol water raw material or the inert gas is realized by adjusting the first manual regulating valve and the second manual regulating valve.

8. The methanol reforming hydrogen purification system of claim 1, wherein, The methanol reforming hydrogen purification system further comprises a hydrogen removal device, which is located downstream of the PSA purification unit.

9. The methanol reforming hydrogen purification system of claim 1, wherein, The product hydrogen in a product hydrogen tank is delivered into the PSA purification unit, and the flushed gas is delivered into the methanol combustion heating unit as back-burning gas to be combusted again to release heat.

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