Improved methanol water reforming SOFC heat exchange system

Abstract

The application discloses an improved methanol water reforming SOFC heat exchange system and belongs to the technical field of fuel cell power generation system heat exchange. The system comprises a water distribution tank, an air preheater, a methanol water preheater, a methanol water vaporizer, a reforming gas preheater, a combustion furnace, a reforming reactor, a water cooler and an air radiator; the upper portion of the combustion furnace is provided with an air coil, and the lower portion is provided with a heat conduction oil jacket; the heat conduction medium inlet of the reforming reactor is connected with the oil outlet at the upper portion of the heat conduction oil jacket, and the heat conduction medium outlet of the reforming reactor is connected with the oil inlet at the lower portion of the heat conduction oil jacket; the nitrogen pressure in the heat conduction oil jacket is controlled to make the heat conduction oil partially gasify; the heat conduction oil is self-circulated between the heat conduction oil jacket and the reforming reactor by virtue of the density difference, so as to provide heat for the reforming reactor; the reforming gas tail gas discharged from the SOFC is sequentially subjected to two-stage preheating and recycling through the reforming gas preheater and the methanol water preheater, and the heat-exchanged reforming gas tail gas is dehydrated through the water distribution tank and then enters the combustion furnace for incineration. The system reduces power consumption, improves power generation capacity and reduces the methanol consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat exchange technology of fuel cell power generation system, and particularly relates to a heat exchange system of methanol water reforming SOFC. BACKGROUND

[0002] Solid oxide fuel cell (SOFC) is a full solid-state chemical power generation device which can efficiently and environmentally friendly convert the chemical energy stored in fuel and oxidant into electrical energy under medium-high temperature conditions, and is the fuel cell with the highest theoretical energy density. Hydrogen is the ideal fuel of SOFC, but there is a problem of difficult storage and transportation. Methanol is used as a carrier of hydrogen, and hydrogen is prepared by reforming methanol and then used for SOFC power generation.

[0003] At present, the heat exchange of SOFC power generation system mainly has the following problems: generally, heat conduction oil is used as a heat transfer medium to provide heat for the reforming reactor, and for small power generation system, the electric quantity consumed by the circulating pump in the process of driving the heat conduction oil to circulate is large, accounting for about 10-20% of the total power generation. The water vapor (v / v: 52%) and CO2 (v / v: 24%) contained in the tail gas of the cell fuel will produce acidic condensed water in the waste heat utilization process, which is easy to corrode the equipment and block the pipeline. The flame of the tail gas burner goes upward, and the high-temperature flue gas forms a counter-flow heat exchange with the heat conduction oil, which is not conducive to the self-circulation of the heat conduction oil, and the air heater is far away from the combustion zone, resulting in low heat transfer efficiency in the high-temperature zone and large methanol supplement. In view of the foregoing problems, the present application provides an improved methanol water reforming SOFC heat exchange system. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide an improved methanol water reforming SOFC heat exchange system.

[0005] The technical problem is solved by the present application by adopting the following technical scheme:

[0006] An improved methanol water reforming SOFC heat exchange system, comprising a water distribution tank, an air preheater, a methanol water preheater, a methanol water vaporizer, a reforming gas preheater, a combustion furnace, a reforming reactor, a water cooler and an air radiator; characterized in that,

[0007] The upper portion of the combustion furnace is provided with an air coil, and the lower portion is provided with a heat-conducting oil jacket; the water outlet of the water distribution tank is connected with the cold side inlet of the methanol water preheater, the cold side outlet of the methanol water preheater is connected with the cold side inlet of the methanol water vaporizer, the hot side outlet of the methanol water preheater is connected with the inlet of the air radiator, and the outlet of the air radiator is connected with the air inlet of the water distribution tank; the cold side outlet of the methanol water vaporizer is connected with the methanol water inlet of the reforming reactor, the hot side inlet of the methanol water vaporizer is connected with the tail gas outlet of the combustion furnace, and the hot side outlet of the methanol water vaporizer discharges the tail gas of the combustion furnace; the heat-conducting medium inlet of the reforming reactor is connected with the oil outlet of the upper portion of the heat-conducting oil jacket, and the heat-conducting medium outlet of the reforming reactor is connected with the oil inlet of the lower portion of the heat-conducting oil jacket; the nitrogen pressure in the heat-conducting oil jacket is controlled to make the heat-conducting oil partially gasify, and the heat-conducting oil is self-circulated between the heat-conducting oil jacket and the reforming reactor by virtue of the density difference; the reforming gas outlet of the reforming reactor is connected with the cold side inlet of the reforming gas preheater, the cold side outlet of the reforming gas preheater is connected with the fuel inlet of the SOFC, the fuel outlet of the SOFC is connected with the hot side inlet of the reforming gas preheater, and the hot side outlet of the reforming gas preheater is connected with the hot side inlet of the methanol water preheater.

[0008] The reforming gas inlet at the top of the combustion furnace is connected with the air outlet of the water distribution tank, and the flame in the combustion furnace burns from top to bottom; the air inlet of the air coil is connected with air, the air outlet of the air coil is connected with the air inlet of the SOFC, the tail gas outlet of the SOFC is connected with the hot side inlet of the air preheater, the hot side outlet of the air preheater discharges the tail gas of the SOFC, the cold side inlet of the air preheater is connected with air, and the cold side outlet of the air preheater is connected with the air inlet of the SOFC; the hot side inlet of the water cooler is connected with the tail gas outlet of the combustion furnace.

[0009] Further, the temperature of the cold side outlet of the methanol water vaporizer is 180-300℃, the temperature of the reforming gas outlet of the reforming reactor is 210-290℃, the temperature of the heat-conducting oil jacket is 240-300℃, the temperature of the outlet of the air radiator is 25-80℃, the temperature of the cold side outlet of the air preheater is 550-720℃, the temperature of the outlet of the air coil is 450-850℃, and the temperature of the air inlet of the SOFC is 600-750℃.

[0010] Further, the nitrogen pressure in the heat-conducting oil jacket is 100-500kPa(A).

[0011] Further, more air should be introduced into the air coil in the system starting stage, and more air should be introduced into the air preheater in the normal operation stage.

[0012] Compared with the prior art, the present application has the following advantages:

[0013] 1. The reforming reactor is directly connected with the heat conducting oil jacket of the lower part of the combustion furnace. The temperature of the heat conducting oil in the heat conducting oil jacket is increased and partially gasified, forming a low density area. The temperature of the heat conducting oil in the reforming reactor is low and the density is large, so the heat conducting oil realizes self-circulation between the heat conducting oil jacket and the reforming reactor by the density difference, providing heat for the reforming reactor and saving the circulating pump. For a small power generation system, the power generation capacity can be increased by 10%-20%. In order to strengthen the circulating effect of the heat conducting oil, the nitrogen pressure in the heat conducting oil jacket is adjusted to make the heat conducting oil in the heat conducting oil jacket partially gasified to reduce the liquid phase density, so that a larger density difference is formed between the heat conducting oil jacket and the reforming reactor, and the self-circulation speed of the heat conducting oil is increased.

[0014] 2. In the combustion furnace, the methanol combustion flame directly heats the air coil to provide the heat required for the start of the SOFC stack. This heating method has the advantages of large heat transfer coefficient and high heat exchange efficiency, and the methanol consumption is reduced by 5-10%. The air flow in the air coil and the air preheater is adjusted according to the operating temperature of the stack to enhance the adjustability and stability of the SOFC operating temperature.

[0015] 3. The flame position of the combustion furnace is located at the upper part, and the temperature distribution gradually decreases from top to bottom. The combustion tail gas successively passes through the air coil and the heat conducting oil jacket, and the heat conducting oil in the heat conducting oil jacket flows from bottom to top. The heat conducting oil and the combustion tail gas form counter-flow heat exchange, and the heat exchange efficiency is increased by about 5%.

[0016] 4. The reforming gas tail gas of the SOFC realizes two-stage waste heat utilization and recycling of water condensate. First, it is heated by the reforming gas through the reforming gas preheater, and then it is heated by the methanol water through the methanol water preheater. After heat exchange, the reforming gas tail gas passes through the air radiator and enters the water separation tank to separate the condensed water, realizing the dehydration of the reforming gas tail gas. The volume concentration of hydrogen in the tail gas is increased from 20-30% to more than 35%, which slows down the corrosion rate of the combustion furnace and reduces the amount of tail gas. The separated condensed water can be recycled for reforming hydrogen, and no water needs to be supplemented during operation, realizing water recycling. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the heat exchange system of the present application.

[0018] Among them: 1-35 are pipelines; P1 is a water metering pump; P2 is a methanol metering pump; K1-K5 are valves; V1 is a water separation tank; E1 is an air preheater; E2 is a methanol water preheater; E3 is a methanol water vaporizer; E4 is a reforming gas preheater; E5 is a combustion furnace; E6 is a reforming reactor; E7 is a water cooler; E8 is an air radiator. DETAILED DESCRIPTION

[0019] The specific embodiments are described below with reference to the accompanying drawings, which are only used to specifically introduce the technical solutions of the present application, and do not limit the protection scope of the present application.

[0020] Referring to Figure 1 The present application provides an improved methanol water reforming SOFC heat exchange system, which comprises a water distribution tank V1, an air preheater E1, a methanol water preheater E2, a methanol water vaporizer E3, a reforming gas preheater E4, a combustion furnace E5, a reforming reactor E6, a water cooler E7 and an air radiator E8; the upper part of the combustion furnace E5 is provided with an air coil a, and the lower part is provided with a heat conducting oil jacket b;

[0021] The water outlet at the lower end of the water distribution tank V1 is divided into two paths through three pipes 3, one path is connected with a water outlet through a pipe 1 and a first valve K1, and the other path is connected with the inlet of a water metering pump P1 through a pipe 2, the outlet of the water metering pump P1 is connected with the cold side inlet of the methanol water preheater E2 through a sixteen pipe and an eighteen pipe 18, the water inlet at the upper part of the water distribution tank V1 is connected with a water supplement inlet through a four pipe 4 and a second valve K2, the gas outlet at the upper end of the water distribution tank V1 is connected with the reforming gas inlet at the top of the combustion furnace E5 through a fourteen pipe 14, the cold side inlet of the methanol water preheater E2 is connected with protective gas and methanol through an eleven pipe 11 and a twelve pipe 12 respectively, the methanol in this part is used as the fuel of the SOFC, and the twelve pipe 12 is provided with a methanol metering pump P2; the cold side outlet of the methanol water preheater E2 is connected with the cold side inlet of the methanol water vaporizer E3 through a nineteen pipe 19, the hot side outlet of the methanol water preheater E2 is connected with the inlet of the air radiator E8 through a fifteen pipe 15, and the outlet of the air radiator E8 is connected with the gas inlet at the upper part of the water distribution tank V1 through a thirty-four pipe 34; the cold side outlet of the methanol water vaporizer E3 is connected with the methanol water inlet of the reforming reactor E6 through a twenty pipe 20, the hot side inlet of the methanol water vaporizer E3 is connected with the tail gas outlet at the lower end of the combustion furnace E5 through a twenty-one pipe 21 and a sixth pipe 6, the hot side outlet of the methanol water vaporizer E3 is connected with the tail gas outlet through a thirteen pipe 13; the heat conducting oil inlet of the reforming reactor E6 is connected with the oil outlet at the upper part of the heat conducting oil jacket b of the combustion furnace E5 through a thirty-two pipe 32, the heat conducting oil outlet of the reforming reactor E6 is connected with the oil inlet at the lower part of the heat conducting oil jacket b of the combustion furnace E5 through a thirty-three pipe 33, the reforming gas outlet of the reforming reactor E6 is connected with the cold side inlet of the reforming gas preheater E4 through a twenty-three pipe 23, the cold side outlet of the reforming gas preheater E4 is connected with the fuel inlet of the SOFC through a twenty-four pipe 24, the fuel outlet of the SOFC is connected with the hot side inlet of the reforming gas preheater E4 through a twenty-five pipe 25, and the hot side outlet of the reforming gas preheater E4 is connected with the hot side inlet of the methanol water preheater E2 through a twenty-two pipe 22;

[0022] The methanol inlet and air inlet of the combustion furnace E5 upper part are connected to methanol and air through five pipes 5 and seven pipes 7 respectively, the air inlet of the air coil a of the combustion furnace E5 is connected to air through twenty-six pipes 26 and eight pipes 8, the third valve K3 is arranged on the twenty-six pipes 26, the air outlet of the air coil a is connected to the air inlet of the SOFC through thirty pipes 30 and thirty-one pipes 31, the tail gas outlet of the SOFC is connected to the hot side inlet of the air preheater E1 through twenty-nine pipes 29, the hot side outlet of the air preheater E1 is connected to the tail gas outlet through nine pipes 9, the cold side inlet of the air preheater E1 is connected to air through twenty-seven pipes 27 and eight pipes 8, the fourth valve K4 is arranged on the twenty-seven pipes 27, the cold side outlet of the air preheater E1 is connected to the air inlet of the SOFC through twenty-eight pipes 28 and thirty-one pipes 31; the hot side inlet of the water cooler E7 is connected to the tail gas outlet at the lower end of the combustion furnace E5, the hot side outlet is connected to the tail gas outlet through ten pipes 10, the fifth valve K5 is arranged on the ten pipes 10, the cold side inlet of the water cooler E7 is connected to the cold water inlet through thirty-five pipes 35, and the cold side outlet is connected to the hot water outlet through thirty-four pipes 34.

[0023] In order to ensure that the methanol water enters the reforming reactor in the form of gas phase and the catalyst is not deactivated at high temperature, the temperature of the cold side outlet of the methanol water vaporizer E3 is 180-300 DEG C, and the preferable temperature is 200-290 DEG C; the temperature of the reforming gas outlet of the reforming reactor is 210-290 DEG C, and the preferable temperature is 240-280 DEG C; the temperature of the heat conducting oil jacket is 240-300 DEG C, and the preferable temperature is 250-290 DEG C; the nitrogen pressure in the heat conducting oil jacket is adjusted to 100-500 kPa (A) to control the gasification fraction of the heat conducting oil.

[0024] In order to improve the methanol conversion rate of the reforming reaction, the molar ratio of water to methanol in the methanol water is controlled to be 1.0-1.3.

[0025] In order to ensure the dehydration effect of the reforming gas tail gas, the outlet temperature of the air radiator is 25-80 DEG C, and the preferable temperature is 25-50 DEG C, so that the water is condensed and enriched in the water separation tank. The cold side outlet temperature of the air preheater is 550-720 DEG C, and the preferable temperature is 600-700 DEG C; the outlet temperature of the air coil is 450-850 DEG C, and the preferable temperature is 650-820 DEG C; the air inlet temperature of the SOFC is 600-750 DEG C, and the preferable temperature is 600-700 DEG C.

[0026] The working principle and working process of the application are as follows:

[0027] Methanol and air are divided into two ways, one way into the SOFC, the other way into the combustion furnace. One way of methanol is introduced into the system through twelve pipes 12 and is quantitatively calculated by methanol metering pump P2, and water in the water distribution tank V1 is introduced into the system according to the proportion by water metering pump P2, and methanol and water are mixed in the pipeline to form a methanol water solution, which enters the methanol water preheater E2, and the methanol water exchanges heat with the reforming gas tail gas from the reforming gas preheater E4 to be warmed up and partially gasified to form a gas-liquid mixture of methanol water; the gas-liquid mixture of methanol water enters the methanol water vaporizer E3 through nineteen pipes 19, exchanges heat with the high-temperature tail gas from the combustion furnace E5, and the temperature is further increased to make the methanol water completely gasified to form methanol water gas; the methanol water gas enters the reforming reactor E6 as raw material, and the reforming reaction occurs under the action of the catalyst to generate reforming gas containing hydrogen, carbon dioxide, and a small amount of carbon monoxide and unreacted methanol water; the reforming gas enters the reforming gas preheater E4, exchanges heat with the reforming gas tail gas from the SOFC, and is warmed up to a higher temperature, and then enters the SOFC as fuel.

[0028] The SOFC converts the chemical energy of the reforming gas into electrical energy, and the electrolyte used by the SOFC is an oxide ceramic, which has the ability to transfer oxygen ions, so that the reforming gas tail gas discharged from the SOFC contains carbon dioxide, water, and unused hydrogen, carbon monoxide, etc. The reforming gas tail gas is discharged from the fuel outlet of the SOFC and enters the reforming gas preheater E4, and in the reforming gas preheater E4, the reforming gas tail gas transfers heat to the reforming gas, and the cooled reforming gas tail gas enters the methanol water preheater E2 through twenty-two pipes 22, exchanges heat with the methanol water, and is cooled and liquefied again, and further cooled by the air radiator E8 to produce a large amount of liquid water to form a gas-liquid mixture of reforming gas tail gas; the gas-liquid mixture of reforming gas tail gas enters the water distribution tank V1 for gas-liquid separation to realize the removal of the reforming gas tail gas, and a part of the separated water is collected in the tank to provide raw material for preparing methanol water solution, and the excess water is discharged regularly through the drain; the dehydrated reforming gas tail gas enters the combustion furnace E5 through fourteen pipes 14 for incineration.

[0029] Another methanol is sent into the combustion furnace E5 through five pipes 5, and is ignited to continuously and stably burn in the furnace as a fire source. Meanwhile, the reforming gas tail gas and air entering into the combustion furnace E5 are ignited, and since the methanol, air and reforming gas tail gas are all introduced into the furnace from the upper part of the combustion furnace 5, a flame is formed to burn from the top to the bottom, and the flame directly contacts the air coil a, and the flame directly heats the coil a to a high temperature, and when air passes through the air coil a, the air is heated, and when no air passes through, the air coil a is kept at a high temperature; meanwhile, the high-temperature tail gas produced by combustion flows from the top to the bottom, and when passing through the heat-conducting oil jacket b below the air coil a, the heat-conducting oil jacket b is heated and warmed, and the heat-conducting oil inside the heat-conducting oil jacket b is partially gasified; since the heat-conducting oil in the heat-conducting oil jacket b is at a high temperature and partially gasified, the density is small, and the heat-conducting oil in the reforming reactor E6 is at a low temperature and has a large density, and under the action of the density difference, the high-temperature heat-conducting oil flows out of the heat-conducting oil jacket of the combustion furnace E5 and enters into the reforming reactor E6, and the high-temperature heat-conducting oil is cooled by heat exchange in the reforming reactor E6, and the cooled heat-conducting oil flows out of the heat-conducting oil outlet of the reforming reactor E6 and returns to the heat-conducting oil jacket b of the combustion furnace E5 for warming, so as to realize the self-circulation of the heat-conducting oil. The heat-conducting oil is heated to a suitable temperature by controlling the nitrogen pressure in the heat-conducting oil jacket, so as to ensure the temperature of the reforming reactor E6.

[0030] One of the air enters into the combustion furnace E5 from the air inlet in the upper part of the combustion furnace E5 as a combustion raw material. Another air enters into the air preheater E1 and the air coil a of the combustion furnace E5, and the air entering into the air preheater E1 exchanges heat with the air tail gas of the SOFC to realize preheating, and the preheated air enters into the SOFC, and part of the oxygen in the air passes through the electrolyte diaphragm in the SOFC and is converted into water, forming air tail gas with a low oxygen content and being discharged from the tail gas outlet of the SOFC, and then the air preheater E1 transfers heat to the air and is cooled to be discharged, realizing the heat exchange of the air side of the SOFC; the air entering into the air coil a is heated by the flame in the combustion furnace E5 and then enters into the SOFC for reaction. In actual operation, the air flow in the air preheater E1 and the air coil a is adjusted according to the working condition, and in the system starting stage, the third valve K3 is adjusted to make more air enter into the air coil a; in the system normal running stage, the fourth valve K4 is adjusted to make more air enter into the air preheater E1 to exchange heat with the air tail gas from the SOFC.

[0031] Embodiment

[0032] This embodiment takes the SOFC system with the designed output electric power of 1 kW as an example to illustrate the working process and related process parameters of the SOFC under the conditions of no-load start and designed load. The mass fraction of methanol is ≥99%, the protective gas is composed of 5% hydrogen and 95% nitrogen, and the water supplement port of the water separation tank is connected to deionized water.

[0033] SOFC no-load start stage:

[0034] Before the start of the system, the valves K1, K4 and K5 are kept closed, and the valves K2 and K3 are kept open. After about half a tank of water is supplemented to the water separation tank V1 through the water supplement port, the valve K2 is closed. Air and methanol are introduced into the combustion furnace E5, the flow rate of the methanol is 0.1 kg / h, and the flow rate of the air is 60 L / min. The air and the methanol are mixed in the combustion furnace E5, the methanol is ignited by the ignition device, and a stable burning flame is formed in the combustion furnace E5. The flame maintains a stable burning state during the operation of the system.

[0035] The protective gas port is connected to an external gas cylinder containing hydrogen-containing nitrogen as the protective gas, and the flow rate of the protective gas is about 10 mL / min, which is sent into the system through the eleventh pipeline 11. The protective gas will pass through the methanol water preheater E2, the methanol water vaporizer E3, the reforming reactor E6, the SOFC, the air radiator E8 and the water separation tank V1, and finally enter the combustion furnace E5 for incineration. When passing through the reforming reactor E6 and the SOFC, the protective gas provides a reducing atmosphere for the reforming catalyst and the electrolyte, avoiding the oxidation and denaturation of the internal active components during the heating process.

[0036] In the combustion furnace E5, the air coil a is directly heated by the flame, and the heat conducting oil jacket b is heated by the high-temperature tail gas, so that the temperature of the heat conducting oil in the heat conducting oil jacket b is increased and the density is reduced, forming a low-density area, while the temperature of the heat conducting oil in the reforming reactor E6 is relatively low, forming a high-density area. Under the action of the density difference, the heat conducting oil self-circulates between the heat conducting oil jacket b and the reforming reactor E6, realizing the heat transfer between the combustion furnace E5 and the reforming reactor E6.

[0037] At the same time, air is introduced into the air coil a of the air preheater E1 and the combustion furnace E5, and the air flow is controlled at 130 L / min. The air in the air coil a extracts heat from the combustion furnace E5 for the SOFC warming up. Since the reforming reactor E6 also needs to extract heat from the combustion furnace E5, and the warming up rate of the reforming reactor E6 is slower, in order to achieve the heat distribution of the SOFC and the reforming reactor E6, the valve K3 and the valve K4 are adjusted to make most of the air pass through the air preheater E1, and the rest of the air pass through the air coil a, so that the heat absorption of the air coil a is reduced, and more heat generated by the combustion furnace E5 is distributed to the heat conducting oil jacket b, so that the warming up rates of the SOFC and the reforming reactor E6 are similar. The air in the air preheater E1 exchanges heat with the air tail gas from the SOFC, and the temperature of the twenty-eight pipes 28 at the cold side outlet of the air preheater E1 is basically the same as the temperature of the twenty-nine pipes 29 at the tail gas outlet of the SOFC. The air preheated by the air preheater E1 and the air coil is mixed and then enters the SOFC, so as to realize the preheating and warming up of the SOFC.

[0038] In this embodiment, the opening degrees of the valves K3 and K4 are adjusted to make part of the air pass through the air preheater E1, and the rest of the air pass through the air coil a. The air in the air coil a is heated by the flame to about 470℃. When the temperature of the heat conducting oil in the heat conducting oil jacket b rises to about 250℃, the heat conducting oil starts to partially gasify to form low-density bubbles, which increases the density difference and the circulating driving force of the heat conducting oil, and the heat exchange efficiency is increased, and the temperature of the reforming reactor E6 starts to rapidly rise from 170℃. When the temperature of the SOFC exceeds 150℃, and the temperature of the reforming gas outlet of the reforming reactor E6 exceeds 230℃, the methanol is introduced from the twelve pipes 12 by an external methanol tank, the methanol metering pump P2 and the water metering pump P1 are opened, and the methanol flow is set at 0.1 kg / h and the water flow is set at 0.06 kg / h, the water and the methanol are mixed to form methanol water, and the protective gas is stopped. The methanol water enters the methanol water preheater E2 through the eighteen pipes 18 for heat exchange, and finally the methanol water is heated to 85℃ and stabilized, and then heated to 290℃ by the methanol water vaporizer E3, and then enters the reforming reactor E6 to generate the reforming gas. The temperature of the reforming gas outlet of the reforming reactor E6 is about 240℃, and the reforming gas enters the SOFC after being preheated by the reforming gas preheater E4. Since there is no electrical load, the reforming gas cannot be utilized by the SOFC and is directly discharged as the reforming gas tail gas. The reforming gas tail gas is cooled to about 240℃ by the reforming gas preheater E4 for heat exchange, and then is sent to the methanol water preheater E2 as a heat source to preheat the methanol water, and the temperature of the reforming gas tail gas is reduced to 40℃, and then is cooled to about 30℃ by the air radiator E8 and then is sent to the water separation tank V1. A small amount of water is separated and retained in the water separation tank V1, the gas phase directly enters the combustion furnace E5, the reforming gas tail gas is incinerated in the combustion furnace E5 to convert into heat energy and is transferred to the air coil a and the heat conducting oil jacket b in the furnace, and then provides heat for the SOFC and the reforming reactor E6.

[0039] Since the reforming gas tail gas entering the burner E5 will cause the combustion heat to increase, the heat transfer oil and the reforming reactor E6 temperature rising rate to accelerate. When the reforming reactor E6 reforming gas outlet temperature rises to 280℃, to avoid the reforming reactor E6 over-temperature, and to accelerate the SOFC temperature rising speed, the valve K3 and K4 should be adjusted, so that about half of the air passes through the air preheater E1, the air coil a gas flow is increased to absorb the heat generated by the combustion and the air coil a outlet temperature is about 810℃, the heat absorption of the heat transfer oil jacket b is reduced to avoid the reforming reactor thermal load being too high. When the SOFC temperature reaches above 650℃, it is considered that the SOFC start-up is completed.

[0040] The SOFC runs at the design load:

[0041] The SOFC has the highest efficiency at the design load, at which the SOFC works in the optimal temperature range, and the self-heating and heat loss reach a balance. When running at the design load, the protective gas is closed, the valves K2, K3, K5 are in the closed state, K4 is in the open state, and K1 is in the intermittent open state.

[0042] When the water level in the water separation tank V1 exceeds two-thirds, the valve 1 is opened to discharge the excess water, and when the water level in the water separation tank V1 is below one-half, the valve 1 is closed to stop the water discharge, so as to stabilize the water level in the water separation tank V1, and the average water discharge per hour is 0.2kg; the water in the water separation tank V1 is sent into the system through the water metering pump P1, and the P1 flow is specified to be 0.28kg / h; at the same time, the methanol is sent into the system through the methanol metering pump P2 through the twelfth pipeline 12, and the P2 flow is specified to be 0.43kg / h. After the water and the methanol are mixed to form the methanol water, and enter into the methanol water preheater E2 to exchange heat with the reforming gas tail gas to rise the temperature to 85℃ to form a gas-liquid mixture, and then enter into the methanol water vaporizer E3 to fully exchange heat with the tail gas from the burner E5, the methanol water is completely gasified to form the methanol water gas and the temperature is raised to 235℃, the methanol water gas enters into the reforming reactor E6, and under the action of the internal catalyst, the reforming reaction occurs to become the reforming gas, the highest temperature in the reforming reactor is not more than 290℃, and the discharged reforming gas temperature is about 260℃, the reforming gas enters into the reforming gas preheater E4 to exchange heat with the reforming gas tail gas to rise the temperature to 700℃, and then enters into the SOFC as the fuel. Since the SOFC generates heat during the power generation process, the reforming gas tail gas of the SOFC is heated to 730℃, the reforming gas tail gas is cooled to 315℃ through the reforming gas preheater E4, and then enters into the methanol water preheater E2 to exchange heat again to reduce the temperature to 90℃, and then enters into the air radiator E8 to reduce the temperature to 47℃, and then is sent to the water separation tank V1 to remove the condensed water, and the dehydrated reforming gas tail gas enters into the burner E5 to be incinerated.

[0043] Air enters into the air preheater E1 at a flow rate of 120 L / min, exchanges heat with the air tail gas from the SOFC to be heated to 635℃, and is then sent into the SOFC. In the SOFC, a part of the oxygen in the air is consumed by the SOFC to form the air tail gas which is discharged through the SOFC air outlet. The air tail gas exchanges heat with the air in the hot stream side of the air preheater E1 to be cooled to 220℃, and is then discharged as the tail gas. Methanol and air are introduced into the combustion furnace E5, and the flow rate of the methanol is controlled to be 0.1 kg / h, and the flow rate of the air is controlled to be 80 L / min. The methanol and the air are mixed in the combustion furnace E5 and are ignited to form a stable flame in the combustion furnace E5. At the same time, the reforming gas tail gas from the water tank V1 is introduced into the combustion furnace E5 and is ignited to form a flame which burns downward. The flame first passes through the air coil a, and the outlet temperature of the air coil a is heated to 670℃. The residual heat generated by the combustion is absorbed by the heat conducting oil jacket b. Since the heat conducting oil in the heat conducting oil jacket b is partially gasified to absorb the heat, the temperature of the heat conducting oil is restricted by its own boiling range. The excess heat causes the heat conducting oil to be partially gasified to form low-density bubbles which push the heat conducting oil to flow through the pipeline 32 to the reforming reactor E6. The temperature of the heat conducting oil in the pipeline 32 is 280℃. At the same time, the heat conducting oil in the reforming reactor E6 is sucked into the heat conducting oil jacket b through the pipeline 33 to realize the self-circulation of the heat conducting oil between the combustion furnace E5 and the reforming reactor E6.

[0044] The 340℃ tail gas generated by the combustion furnace E5 is divided into two paths through the six pipelines 6. One path passes through the methanol water vaporizer E3 as the hot stream to preheat and heat the methanol water to 85℃, and is then discharged as the tail gas through the pipeline 13 after being cooled. The other path enters into the water cooler E7 to exchange heat to heat the normal temperature water in the water cooler E7 to 60℃, and is then discharged as the tail gas through the pipeline 10. When the outlet temperature of the cold side of the methanol water vaporizer E3 exceeds 290℃, the fifth valve K5 can be partially opened to adjust the temperature. In this embodiment, the fifth valve K5 can be kept closed.

[0045] The designed power generation capacity of this embodiment is 1 kW, and the actually measured long-term stable net power generation capacity is 0.89 kW. The flow rates of the partial pipelines of the system are as follows:

[0046]

[0047] Since the power generation capacity is affected by the power generation stack, the power generation efficiency of this embodiment is only for reference, and is not the highest efficiency that can be achieved by the system. Therefore, the application range of the system cannot be limited by the power generation efficiency.

[0048] The unmentioned parts of the present application are applicable to the prior art.

Claims

1. An improved methanol water reforming SOFC heat exchange system, comprising a water distributor, an air preheater, a methanol water preheater, a methanol water vaporizer, a reforming gas preheater, a combustion furnace, a reforming reactor, a water cooler and an air radiator; characterized in that, the upper part of the combustion furnace is provided with an air coil, and the lower part is provided with a heat conducting oil jacket; the water outlet of the water distributor is connected with the cold side inlet of the methanol water preheater, the cold side outlet of the methanol water preheater is connected with the cold side inlet of the methanol water vaporizer, the hot side outlet of the methanol water preheater is connected with the inlet of the air radiator, and the outlet of the air radiator is connected with the air inlet of the water distributor; the cold side outlet of the methanol water vaporizer is connected with the methanol water inlet of the reforming reactor, the hot side inlet of the methanol water vaporizer is connected with the tail gas outlet of the combustion furnace, and the hot side outlet of the methanol water vaporizer discharges the tail gas of the combustion furnace; the heat conducting medium inlet of the reforming reactor is connected with the oil outlet of the upper part of the heat conducting oil jacket, and the heat conducting medium outlet of the reforming reactor is connected with the oil inlet of the lower part of the heat conducting oil jacket; the nitrogen pressure in the heat conducting oil jacket is controlled to make the heat conducting oil partially gasify, and the heat conducting oil is self-circulated between the heat conducting oil jacket and the reforming reactor by density difference; the reforming gas outlet of the reforming reactor is connected with the cold side inlet of the reforming gas preheater, the cold side outlet of the reforming gas preheater is connected with the fuel inlet of the SOFC, the fuel outlet of the SOFC is connected with the hot side inlet of the reforming gas preheater, and the hot side outlet of the reforming gas preheater is connected with the hot side inlet of the methanol water preheater; the reforming gas inlet at the top of the combustion furnace is connected with the air outlet of the water distributor, and the flame in the combustion furnace burns from top to bottom; the air inlet of the air coil is connected with the air inlet of the SOFC, the tail gas outlet of the SOFC is connected with the hot side inlet of the air preheater, the hot side outlet of the air preheater discharges the tail gas of the SOFC, the cold side inlet of the air preheater is connected with the air inlet of the SOFC, and the cold side outlet of the air preheater is connected with the air inlet of the SOFC; the hot side inlet of the water cooler is connected with the tail gas outlet of the combustion furnace; the temperature of the cold side outlet of the methanol water vaporizer is 180-300℃, the temperature of the reforming gas outlet of the reforming reactor is 210-290℃, the temperature of the heat conducting oil jacket is 240-300℃, and the nitrogen pressure in the heat conducting oil jacket is 100-500kPa(A).

2. The improved methanol water reforming SOFC heat exchange system according to claim 1, characterized in that, the temperature of the outlet of the air radiator is 25-80℃, the temperature of the cold side outlet of the air preheater is 550-720℃, the temperature of the outlet of the air coil is 450-850℃, and the temperature of the air inlet of the SOFC is 600-750℃.

3. The improved methanol water reforming SOFC heat exchange system according to claim 1, characterized in that, More air should be introduced into the air coil in the system starting stage, and more air should be introduced into the air preheater in the normal operation stage.

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