WO2024027073A1 - Method and system for co-producing steam in power generation process - Google Patents

Abstract

A system for co-producing steam in a power generation process, which comprises a fuel cell, a gas supply unit, an oxygen supply unit, a first steam generation unit and/or a second steam generation unit. In the system, the fuel cell uses a fuel gas provided by the anode of the fuel cell and oxygen provided by the cathode of the fuel cell to carry out power generation reaction and produce an anode tail gas and a cathode tail gas. The anode tail gas exchanges heat with water at the first steam generation unit to generate steam, and the cathode tail gas exchanges heat with water at the second steam generation unit to generate steam, so as to realize heat-power co-production. The invention combines fuel cell power generation with the steam production process, utilizes cheap resources such as industrial purge gases and refinery tail gases as the fuel gases of the fuel cell for power generation, and then utilizes heat of the tail gas of power generation to produce steam, thereby improving the residual heat quality of the fuel cell and saving natural gas resources.

Description

A method and system for co-generating steam during power generation Technical field

The present invention relates to the technical fields of energy development and energy conversion, and in particular to a method and system for co-generating steam in the power generation process.

Background technique

As an important power and raw material for refining and chemical production equipment, steam is mainly produced directly by steam boilers. Waste heat boilers are also one of the sources of steam. The higher the steam pressure, the higher the quality and the more suitable it is for use as power. In the existing technology, in order to reduce the cost of steam manufacturing, most steam boilers use coal, residual oil, purge gas and refinery exhaust gas as raw materials in the production process, and use the combustion of the above raw materials to produce steam. The purge gas and refinery exhaust gas during the production process can not only be used as fuel for steam production, but also can be directly used as fuel without reforming after removing sulfur and nitrogen impurities due to their high hydrogen content. The solid oxide fuel cell anode provides fuel for power generation. The solid oxide fuel cell (SOFC) is an all-solid-state power generation device that can efficiently convert hydrocarbon-containing fuels such as coal, oil, and natural gas into electrical energy. Its operating temperature is between 600 -1000°C, and its power generation process is not limited by the Carnot cycle. It can produce a large amount of high-temperature exhaust gas while generating power.

Contents of the invention

The inventor found that when coal-fired boilers produce steam, the carbon dioxide emission intensity is high and the cost of carbon emission treatment is high. The high-temperature exhaust gas generated by solid oxide fuel cells contains a large amount of heat energy. The existing technology is mainly used to co-produce hot water. If it can be used to co-produce steam, the waste heat quality can be significantly improved and carbon dioxide emissions during the steam production process can be significantly reduced.

In view of the above problems, the present invention is proposed to provide a method and system for co-generating steam in a power generation process that overcomes the above problems or at least partially solves the above problems.

In a first aspect, embodiments of the present invention provide a system for co-generating steam in a power generation process, including: a fuel cell, a gas supply unit, an oxygen supply unit, and a first steam generation unit and/or a second steam generation unit;

The gas supply unit is connected to the anode of the fuel cell to provide fuel gas for the fuel cell;

The oxygen supply unit is connected to the cathode of the fuel cell to provide oxygen to the fuel cell;

The fuel cell is used to generate electricity using the fuel gas and the oxygen and produce anode exhaust gas and cathode exhaust gas;

A first steam generation unit, connected to the anode, is used to generate steam by exchanging heat with water between the anode exhaust gas generated by the anode;

The second steam generation unit is connected to the cathode and is used to generate steam by exchanging heat with water between the cathode exhaust gas generated by the cathode.

In some optional embodiments, the air supply unit includes: a purifier and an air supply preheating device;

The purifier is used to treat impurities in the initial fuel gas;

The air supply preheating device includes a first heat exchanger and a second heat exchanger, the first heat exchanger is connected to the purifier, and the second heat exchanger is connected to the fuel cell; The gas supply preheating device is used to preheat the treated fuel gas so that the fuel gas reaches the first preset temperature and is supplied to the anode of the fuel cell.

In some optional embodiments, the oxygen supply unit includes: a cathode exhaust gas storage tank, a compressor and an oxygen supply preheating device;

The cathode tail gas storage tank is connected to the second steam generation unit and is used to store the cathode tail gas and/or newly injected oxygen, and mix the cathode tail gas and the newly injected oxygen to obtain mixed oxygen, and the cathode tail gas is not yet reacting oxygen;

The compressor is connected to the cathode tail gas storage tank and is used to compress the cathode tail gas, newly injected oxygen or mixed oxygen to reach a preset pressure;

The oxygen supply preheating device is used to preheat the compressed cathode tail gas, newly injected oxygen or mixed oxygen to reach the second preset temperature.

In some optional embodiments, the first steam generation unit includes a third heat exchanger and a fourth heat exchanger, and the third heat exchanger is connected to the fuel cell anode to utilize anode exhaust gas and water to conduct The heat exchange produces the first medium-pressure steam, and the fourth heat exchanger is connected to the third heat exchanger to use the anode tail gas and water to exchange heat to produce the first low-pressure steam;

The second steam generation unit includes a fifth heat exchanger and a sixth heat exchanger. The fifth heat exchanger is connected to the cathode of the fuel cell to generate second medium-pressure steam using cathode exhaust gas. The sixth heat exchanger The heat exchanger is connected to the fifth heat exchanger to produce second low-pressure steam using the cathode exhaust gas.

In some optional embodiments, the system for co-generating steam in the power generation process also includes a third steam generation unit,

The third steam generation unit includes a positive gas tail gas burner, a seventh heat exchanger, an eighth heat exchanger and a ninth heat exchanger;

The positive gas tail gas burner is connected to the fourth heat exchanger for burning unreacted fuel gas in the anode tail gas to produce combustion products, and the positive gas tail gas burner is connected to an oxygen supply preheating device and a second heat exchanger. The heater is connected to allow the combustion products to preheat the fuel gas and oxygen;

The seventh heat exchanger is connected to the second heat exchanger and the oxygen supply preheating device to produce third medium-pressure steam by exchanging heat between the preheated combustion products and water;

The eighth heat exchanger is connected to the seventh heat exchanger to utilize combustion products and water to exchange heat to produce third low-pressure steam;

The ninth heat exchanger is connected to the eighth heat exchanger to produce hot water and vent combustion products.

In some optional embodiments, the eighth heat exchanger is connected to the first heat exchanger to preheat the fuel gas using third low-pressure steam.

Based on the same inventive concept, an embodiment of the present invention also provides a method for co-generating steam in the power generation process using the above system. The steps are as follows:

The gas supply unit provides fuel gas for the anode of the fuel cell, and the oxygen supply unit provides oxygen for the cathode of the fuel cell;

Utilize the fuel gas and oxygen to perform a power generation reaction in a fuel cell and generate anode exhaust gas and cathode exhaust gas;

The first steam generation unit uses the anode tail gas and water to exchange heat to produce steam, and/or the second steam generation unit uses the cathode tail gas and water to exchange heat to produce steam.

In some optional embodiments, the gas supply unit provides fuel gas for the anode of the fuel cell, including:

The gas supply unit purifies and preheats the initial fuel gas so that the fuel gas reaches a first preset temperature and is supplied to the anode of the fuel cell for reaction.

In some optional embodiments, the oxygen supply unit provides oxygen for the cathode of the fuel cell, including:

The oxygen supply unit compresses and preheats the newly injected oxygen, the cathode tail gas, or the mixed oxygen of the newly injected oxygen and the cathode tail gas, so that it reaches the preset pressure and the second preset temperature, and then provides it to the fuel The reaction takes place at the cathode of the battery.

In some optional embodiments, the first steam generation unit uses the anode tail gas and water to exchange heat to produce steam, and/or the second steam generation unit uses the cathode tail gas and water to exchange heat to produce steam. Steam, including:

The first steam generation unit uses the anode tail gas to perform heat exchange in the third heat exchanger and the fourth heat exchanger to produce first medium pressure steam and first low pressure steam;

The second steam generation unit uses the cathode exhaust gas to perform heat exchange in the fifth heat exchanger and the sixth heat exchanger to produce second medium pressure steam and second low pressure steam.

In some optional embodiments, the above method further includes:

The third steam generation unit uses the combustion products of the unreacted fuel gas to perform heat exchange in the seventh heat exchanger, the eighth heat exchanger and the ninth heat exchanger to produce third medium pressure steam, third Low pressure steam and hot water.

In some optional embodiments, the third low-pressure steam preheats the fuel gas;

The combustion products of the unreacted fuel gas are the fuel gas and the oxygen, which are preheated.

In some optional embodiments, the hydrogen content of the initial fuel gas is not less than 30%;

The pressure of newly injected oxygen in the cathode tail gas storage tank is not higher than 4MPa;

After the cathode exhaust gas is pressurized by the compressor, the pressure is not higher than 2MPa.

In some optional embodiments, the first preset temperature of the fuel gas entering the fuel cell anode after preheating is not lower than 700°C; after the anode exhaust gas produces the first medium-pressure steam, its temperature is not low At 400℃, after producing the first low-pressure steam, its temperature shall not be lower than 200℃.

In some optional embodiments, the second preset temperature of the oxygen entering the fuel cell cathode after preheating is not lower than 700°C; after the cathode exhaust gas produces the second medium-pressure steam, the temperature is not lower than 400°C, After the second low-pressure steam is produced, the temperature shall not be lower than 150°C.

The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

The method and system for co-generating steam in the power generation process provided by the embodiments of the present invention use the fuel gas provided by the gas supply unit to the anode and the oxygen supply unit to provide oxygen to the cathode in the fuel cell for power generation reaction, and generate anode tail gas and cathode The tail gas, the anode tail gas exchanges heat with water in the first steam generation unit to produce steam, and the cathode tail gas exchanges heat with water in the second steam generation unit to produce steam, thereby realizing cogeneration of heat and power. This co-generation steam method combines the power generation of fuel cells with the steam production process, using cheap resources such as industrial exhaust gas and refinery exhaust gas as fuel gas for the fuel cell to generate electricity, and then using the heat of the power generation exhaust gas to produce steam; This fuel gas does not require a reforming reactor when used for fuel cell power generation, which is conducive to simplifying the reaction system, saving natural gas resources, and reducing investment costs; after using cheap resources such as industrial exhaust gas and refinery exhaust gas as fuel to generate electricity, Using the heat generated by fuel cells to produce steam reduces the amount of carbon dioxide emissions in the process of burning raw materials to produce steam and reduces the cost of carbon emissions compared to directly using cheap resources such as industrial exhaust gas and refinery exhaust to produce steam. , make full use of the heat of power generation exhaust gas, improve the quality of waste heat of the fuel cell, save resources and reduce costs.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

The technical solution of the present invention will be further described in detail below through the accompanying drawings and examples.

Description of the drawings

The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. In the attached picture:

Figure 1 is a schematic structural diagram of a co-generation steam system in the power generation process in an embodiment of the present invention;

Figure 2 is a process flow diagram of the co-generation steam system in the embodiment of the present invention;

Figure 3 is a process flow diagram including a third steam generation unit in an embodiment of the present invention;

Figure 4 is a flow chart of a method for co-generating steam in a power generation process in an embodiment of the present invention.

Reference signs:

1-Purifier, 2-First heat exchanger, 3-Second heat exchanger, 4-Fuel cell, 5-Third heat exchanger, 6-Fourth heat exchanger, 7-Anode tail gas burner, 8 -Oxygen supply preheating device, 9-fifth heat exchanger, 10-sixth heat exchanger, 11-cathode exhaust gas storage tank, 12-compressor, 13-seventh heat exchanger, 14-eighth heat exchanger , 15-ninth heat exchanger.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a thorough understanding of the disclosure, and to fully convey the scope of the disclosure to those skilled in the art.

In order to solve the problems of large carbon dioxide emissions and low quality of solid oxide fuel cell (SOFC) waste heat in the existing steam production process, embodiments of the present invention provide a system and method for co-producing steam in the power generation process. To combine solid oxide fuel cells with steam production to increase the waste heat quality of solid oxide fuel cells.

An embodiment of the present invention provides a system for co-generating steam during power generation, as shown in Figure 1 , including: a fuel cell 4, a gas supply unit 01, an oxygen supply unit 02, a first steam generation unit 03 and/or a Two steam generation units 05;

Among them, the gas supply unit 01 is connected to the anode of the fuel cell 4 to provide fuel gas for the fuel cell 4;

The oxygen supply unit 02 is connected to the cathode of the fuel cell 4 to provide oxygen to the fuel cell 4;

Fuel cell 4 is used to generate electricity using the above-mentioned fuel gas and oxygen and produce anode exhaust gas and cathode exhaust gas;

The first steam generation unit 03 is connected to the anode of the fuel cell and is used to generate steam by exchanging heat between the anode exhaust gas generated by the anode and water;

The second steam generation unit 05 is connected to the cathode of the fuel cell, and is used to generate steam by exchanging heat with water between the cathode exhaust gas generated by the cathode.

The above system combines the power generation of fuel cells with the process of steam production, uses cheap resources such as industrial exhaust gas and refinery exhaust gas as fuel gas for the fuel cell, and then uses the heat of the power generation exhaust gas to produce steam, which can make full use of resources. , compared with the process of burning raw materials to generate steam, it can reduce carbon dioxide emissions and reduce carbon emission costs. At the same time, it makes full use of the heat of the fuel cell power generation tail gas, avoids a large amount of waste of power generation waste heat, and improves the waste heat quality of the fuel cell. Resources can be saved and costs reduced.

In some optional embodiments, a specific structural example of the above system is shown in Figure 2.

The gas supply unit includes: purifier 1 and gas supply preheating device; purifier 1 is used to treat impurities in the initial fuel gas; initial fuel gases such as industrial purge gas and refinery exhaust gas have high hydrogen content, but contain sulfur and nitrogen. After the sulfur and nitrogen impurities are removed by the purifier 1, the impurities can be directly used as fuel gas to enter the fuel cell for power generation reaction without reforming.

Optionally, the air supply preheating device includes at least one heat exchanger. As shown in Figure 2, taking two heat exchangers as an example, the air supply preheating device includes a first heat exchanger 2 and a second heat exchanger 3. , the first heat exchanger 2 is connected to the purifier 1, and the second heat exchanger 3 is connected to the fuel cell 4; the air supply preheating device is used to preheat the treated fuel gas, and the fuel purified by the purifier The gas flows into the first heat exchanger 2 and the second heat exchanger 3 in sequence and undergoes two-stage heat exchange with the preheated material. After the fuel gas reaches the first preset temperature, it is provided to the anode of the fuel cell 4 to preheat the gas. The heat exchangers included in the device only need to enable the fuel gas to reach the first preset temperature when entering the fuel cell. The present invention does not limit the number of specific heat exchangers.

The oxygen supply unit 02 of the embodiment of the present invention provides oxygen to the cathode of the fuel cell. Optionally, it can provide newly injected oxygen, or it can circulate unreacted oxygen at the cathode to the cathode or provide newly injected oxygen and unreacted oxygen at the cathode. The mixed oxygen is supplied to the cathode. The above-mentioned oxygen supply unit 02 includes: cathode tail gas storage tank 11, compressor 12 and oxygen supply preheating device 8;

The cathode exhaust gas storage tank 11 is connected to the second steam generation unit 05 for storing the cathode exhaust gas and/or newly injected oxygen, and mixing the cathode exhaust gas with the newly injected oxygen to obtain mixed oxygen. In the embodiment of the present invention, the fuel cell The power generation reaction does not produce gas at the cathode, so the cathode exhaust gas is unreacted oxygen in the fuel cell 4;

The compressor 12 is connected to the cathode tail gas storage tank 11 and is used to compress the cathode tail gas, newly injected oxygen or mixed oxygen to reach a preset pressure; the oxygen supply preheating device 8 may include at least one heat exchanger for compressing The final cathode exhaust gas, newly injected oxygen or mixed oxygen are preheated to reach the second preset temperature. Optionally, the oxygen supply preheating device 8 includes a specific number of heat exchangers. The invention does not limit it, as long as It is sufficient that the cathode exhaust gas, newly injected oxygen or mixed oxygen can reach the second preset temperature when entering the fuel cell.

The above system can use exhaust gas from the anode and/or cathode of the fuel cell to generate steam. Therefore, the first steam generation unit 03 can be provided at the anode, the second steam generation unit 05 can be provided at the cathode, or both can be provided.

The first steam generation unit 03 may include at least one stage of heat exchanger. As shown in FIG. 2 , taking the first steam generation unit 03 including a two-stage heat exchanger as an example, the first steam generation unit 03 includes a third heat exchanger 5 and the fourth heat exchanger 6. The third heat exchanger 5 is connected to the anode of the fuel cell 4 to use the anode exhaust gas and water to exchange heat to produce the first medium pressure steam. The fourth heat exchanger 6 and the third heat exchanger 5 The anode tail gas is connected to generate the first low-pressure steam by exchanging heat with water. The anode tail gas includes water vapor, carbon dioxide and unreacted fuel gas generated by the fuel cell power generation reaction. The waste heat of the anode tail gas is exchanged with water to generate the first low-pressure steam. Produce steam.

The second steam generation unit 05 may include at least one stage of heat exchanger. For example, the second steam generation unit 05 may include a two-stage heat exchanger. The second steam generation unit 05 may include a fifth heat exchanger 9 and a sixth heat exchanger. 10. The fifth heat exchanger 9 is connected to the cathode of the fuel cell 4 to use the cathode exhaust gas to exchange heat with the water flowing into the fifth heat exchanger to produce second medium-pressure steam. The sixth heat exchanger 10 exchanges heat with the fifth heat exchanger. The device 9 is connected to produce a second low-pressure steam by exchanging heat between the cathode exhaust gas and the water flowing into the sixth heat exchanger.

In some optional embodiments, in addition to using the heat of the anode exhaust gas and the cathode exhaust gas to generate steam through heat exchange, the unburned fuel gas in the anode exhaust gas can also be further used to generate steam. The anode exhaust gas can also be used to generate steam. The heat generated by the combustion of the unburned fuel gas preheats the fuel gas supplied to the anode of the fuel cell. Optionally, another specific structural example of the above system is shown in Figure 3. The system provided by the embodiment of the present invention also includes a third steam generation unit. The third steam generation unit is connected to the first steam generation unit 03 and includes Yang gas tail gas burner 7 and at least one stage heat exchanger. Taking the third steam generation unit including a three-stage heat exchanger as an example, the third steam generation unit includes a seventh heat exchanger 13, an eighth heat exchanger 14 and a third heat exchanger. Nine heat exchangers 15;

The anode exhaust gas burner 7 is connected to the fourth heat exchanger 6 in the first steam generation unit 03 for burning the unreacted fuel gas in the anode exhaust gas to produce combustion products. The anode exhaust gas burner 7 is connected to the oxygen supply preheating device. 8 is connected to the second heat exchanger 3 so that the combustion products of unreacted fuel gas can preheat the fuel gas entering the anode of the fuel cell and the oxygen entering the cathode of the fuel cell;

As shown in Figure 3, the seventh heat exchanger 13 is connected to the second heat exchanger 3 and the oxygen supply preheating device 8 to utilize the combustion products used to preheat the above-mentioned oxygen and fuel gas to pass into the seventh heat exchanger. The water in the heat exchanger 13 performs heat exchange to produce the third medium-pressure steam; the eighth heat exchanger 14 is connected to the seventh heat exchanger 13 to utilize the combustion products and water to perform heat exchange to produce the third low-pressure steam;

The ninth heat exchanger 15 is connected to the eighth heat exchanger 14 so that the combustion products after exchanging heat with the seventh heat exchanger 13 and the eighth heat exchanger 14 are passed into the ninth heat exchanger 15 to exchange heat with water. Produces hot water and vents combustion products.

In the third steam generation unit, the eighth heat exchanger 14 is connected to the first heat exchanger 2 to preheat the purified fuel gas using the third low-pressure steam produced in the eighth heat exchanger 14 .

The above system makes full use of the anode exhaust gas and cathode exhaust gas after fuel cell power generation to generate steam, and further utilizes the unburned fuel gas in the anode exhaust gas to generate steam, and establishes a cycle with the gas supply preheating device to provide fuel gas to the anode. Preheating, etc., through multiple cycles and utilization, the utilization rate of fuel gas can be further improved, the heat and exhaust gas generated in each link can be fully utilized, and the waste of resources can be avoided to the greatest extent.

Based on the same inventive concept, an embodiment of the present invention also provides a method for co-producing steam using the system for co-producing steam in the power generation process. As shown in Figure 4, the steps are as follows:

Step S101: The gas supply unit provides fuel gas for the anode of the fuel cell, and the oxygen supply unit provides oxygen for the cathode of the fuel cell;

Step S102: Utilize fuel gas and oxygen to perform a power generation reaction in the fuel cell and generate anode exhaust gas and cathode exhaust gas;

Step S103: The first steam generation unit uses the anode exhaust gas and water to exchange heat to generate steam, and/or the second steam generation unit uses the cathode exhaust gas and water to exchange heat to generate steam.

In step S101, the air supply unit provides fuel gas for the anode of the fuel cell, including: the air supply unit purifies and preheats the initial fuel gas, so that the fuel gas reaches the first preset temperature and is provided to the anode of the fuel cell for processing. reaction;

The oxygen supply unit provides oxygen to the cathode of the fuel cell and includes:

The oxygen supply unit compresses and preheats the newly injected oxygen, the cathode tail gas, or the mixed oxygen of the newly injected oxygen and the cathode tail gas, so that it reaches the preset pressure and the second preset temperature, and then provides it to the cathode of the fuel cell for processing. reaction. As the installed capacity of renewable energy increases, the gradual increase in water electrolysis devices will bring more by-product oxygen. The newly injected oxygen in the cathode tail gas storage tank can react with the oxygen by-product when electrolyzing water with renewable energy. This will help reduce energy loss and save energy costs.

In step S103, the first steam generation unit uses the anode tail gas and water to exchange heat to produce steam, and/or the second steam generation unit uses the cathode tail gas and water to exchange heat to produce steam, including:

The first steam generation unit uses the anode tail gas to perform heat exchange in the third heat exchanger and the fourth heat exchanger to produce first medium pressure steam and first low pressure steam; the second steam generation unit uses the cathode tail gas to perform heat exchange in the fifth heat exchanger. The second medium-pressure steam and the second low-pressure steam are produced by heat exchange in the first steam generating unit and the sixth heat exchanger; optionally, in step 103, the first medium-pressure steam and/or the first medium-pressure steam can be produced only in the first steam generation unit. Or the first low-pressure steam, the second medium-pressure steam and/or the second low-pressure steam can also be produced only in the second steam generation unit, or the steam can be produced in the first steam generation unit and the second steam generation unit at the same time .

Optionally, in the embodiment of the present invention, when the structural example shown in Figure 3 is used for co-generation of steam, it also includes:

The third steam generation unit connected to the first steam generation unit utilizes the combustion products of the unreacted fuel gas to perform heat exchange in the seventh heat exchanger, the eighth heat exchanger and the ninth heat exchanger to produce a third steam generation unit. Medium pressure steam, third low pressure steam and hot water.

The third low-pressure steam is used to be connected to the first heat exchanger 2 to exchange heat between the purified fuel gas and the third low-pressure steam to preheat the purified fuel gas; after burning the unreacted fuel gas The combustion products preheat the fuel gas entering the anode of the fuel cell and the oxygen entering the cathode of the fuel cell.

The specific implementation process of the co-generation steam method in the power generation process has been described in detail in the relevant embodiments of the co-generation steam system, and will not be described in detail here.

In the process of solid oxide fuel cell power generation and co-generation of steam, the following requirements are set for the relevant parameters of fuel gas and oxygen: the hydrogen content of the initial fuel gas is not less than 30%; the newly injected oxygen content in the cathode tail gas storage tank The pressure is not higher than 4MPa; after the cathode exhaust gas is pressurized by the compressor, the pressure is not higher than 2MPa; the first preset temperature of the fuel gas entering the fuel cell anode after preheating is not lower than 700°C; the first step in the production of the anode exhaust gas After compressing the steam, its temperature shall not be lower than 400°C. After producing the first low-pressure steam, its temperature shall not be lower than 200°C. The second preset temperature of the oxygen entering the fuel cell cathode after preheating is not lower than 700°C; after the cathode tail gas produces the second medium-pressure steam, the temperature is not lower than 400°C; after the second low-pressure steam is produced, the temperature is not lower than 700°C. Below 150℃.

According to different parameters of fuel gas and oxygen, as shown in Figure 3, the process flow of co-generation of steam in the above power generation process is explained as follows:

Example 1: When the hydrogen content of hydrogen-containing fuel gas such as industrial exhaust gas and refinery exhaust gas is 30%, the temperature of the fuel gas entering the solid oxide fuel cell SOFC anode after purification and preheating is 700°C, and the anode after reaction The exhaust gas temperature is 800°C. The pressure of the newly injected fresh oxygen is 4MPa, and the cathode exhaust gas entering the cathode exhaust gas storage tank is pressurized by the supercharger to a pressure of 1.5MPa. The temperature of the cathode reactants entering the solid fuel cell is 720°C, and the temperature of the cathode exhaust gas after the reaction is 820°C. The temperature of the anode exhaust gas leaving the production medium-pressure steam heat exchanger is 500°C, and the temperature leaving the production low-pressure steam heat exchanger is 200°C. The temperature of the cathode exhaust gas leaving the production medium-pressure steam heat exchanger is 500°C, and the temperature leaving the production low-pressure steam heat exchanger is 500°C. The temperature of the unreacted fuel gas is 100℃ when it leaves the hot water heat exchanger. The production indicators are shown in Table 1. Calculated based on 8,760 hours/year, the megawatt-level solid oxide fuel cell has generated a total of 8.55 million kilowatt-hours of electricity, calculated at 0.5 yuan/degree, with an income of 4.275 million yuan, and co-produced 4,300 tons of medium-pressure steam and 4,180 tons of low-pressure steam, each calculated at 200 yuan / ton, 150 yuan / ton, the revenue is 860,000 yuan, 627,000 yuan, the total revenue is 5.762 million yuan, steam revenue accounts for 25.8%.

Table 1 Production index value of hydrogen-containing fuel gas intake volume 2MW (low calorific value) such as industrial exhaust gas and refinery exhaust gas

Example 2: When the hydrogen content of hydrogen-containing fuel gas such as industrial exhaust gas and refinery exhaust gas is 60%, the temperature of the fuel gas entering the solid oxide fuel cell SOFC anode after purification and preheating is 720°C, and the anode after reaction The exhaust gas temperature is 810°C. The pressure of the newly injected fresh oxygen is 3.5MPa, and the cathode exhaust gas entering the cathode exhaust gas storage tank is pressurized by the supercharger to a pressure of 2MPa. The temperature of the cathode reactants entering the solid oxide fuel cell is 700°C, and the temperature of the cathode exhaust gas after the reaction is 800°C. The temperature of the anode tail gas leaving the production medium-pressure steam heat exchanger is 480°C, the temperature leaving the production low-pressure steam heat exchanger is 250°C, the temperature of the cathode tail gas leaving the production medium-pressure steam heat exchanger is 450°C, and the unreacted fuel gas passes through the anode tail gas The burner generates combustion products after combustion. The temperature of the combustion products leaving the low-pressure steam heat exchanger is 180°C; the temperature leaving the hot water heat exchanger is 80°C. The production indicators are shown in Table 2. Calculated based on 8,760 hours/year, the megawatt-level solid oxide fuel cell has generated a total of 9.11 million kilowatt-hours of electricity, calculated at 0.5 yuan/degree, with an income of 4.555 million yuan, and co-produced 4,030 tons of medium-pressure steam and 3,920 tons of low-pressure steam, each calculated at 200 yuan / ton, 150 yuan / ton, the revenue is 806,000 yuan, 588,000 yuan, the total revenue is 5.949 million yuan, steam revenue accounts for 23.4%.

Table 2 Production index value of hydrogen-containing fuel gas intake volume 2MW (low calorific value) such as industrial exhaust gas and refinery exhaust gas

Example 3: When the hydrogen content of hydrogen-containing fuel gas such as industrial exhaust gas and refinery exhaust gas is 100%, the temperature of the fuel gas entering the solid oxide fuel cell SOFC anode after purification and preheating is 710°C, and the anode after reaction The exhaust gas temperature is 820°C. The pressure of the newly injected fresh oxygen is 3MPa, and the cathode exhaust gas entering the cathode exhaust gas storage tank is pressurized by the supercharger to a pressure of 1.8MPa. The temperature of the cathode reactants entering the solid oxide fuel cell is 710°C, and the temperature of the cathode exhaust gas after the reaction is 810°C. The temperature of the anode exhaust gas leaving the production medium-pressure steam heat exchanger is 400°C, and the temperature leaving the production low-pressure steam heat exchanger is 200°C. The temperature of the cathode exhaust gas leaving the production medium-pressure steam heat exchanger is 400°C, and the temperature leaving the production low-pressure steam heat exchanger is 400°C. The temperature of the unreacted fuel gas is 90℃ when it leaves the hot water heat exchanger. The production indicators are shown in Table 3. Calculated based on 8,760 hours/year, the megawatt-level solid oxide fuel cell has generated a total of 10.25 million kilowatt-hours of electricity, calculated at 0.5 yuan/degree, with an income of 5.125 million yuan, and co-produced 3,670 tons of medium-pressure steam and 3,530 tons of low-pressure steam, each calculated at 200 yuan / ton, 150 yuan / ton calculation, the revenue is 734,000 yuan, 530,000 yuan, the total revenue is 6.389 million yuan, steam revenue accounts for 19.8%.

Table 3 Production index values of 2MW (low calorific value) hydrogen-containing fuel gas intake such as industrial exhaust gas and refinery exhaust gas

Example 4: When the hydrogen content of hydrogen-containing fuel gas such as industrial exhaust gas and refinery exhaust gas is 20%, the temperature of the fuel gas entering the solid oxide fuel cell SOFC anode after purification and preheating is 680°C, and the anode after reaction The exhaust gas temperature is 780°C. The pressure of the newly injected fresh oxygen is 4MPa, and the cathode exhaust gas entering the cathode exhaust gas storage tank is pressurized by the supercharger to a pressure of 1.8MPa. The temperature of the cathode reactants entering the solid oxide fuel cell is 700°C, and the temperature of the cathode exhaust gas after the reaction is 770°C. The temperature of the anode exhaust gas leaving the production medium-pressure steam heat exchanger is 380°C, the temperature leaving the production low-pressure steam heat exchanger is 200°C, the temperature of the cathode exhaust gas leaving the production medium-pressure steam heat exchanger is 400°C, and the temperature leaving the production low-pressure steam heat exchanger is 400°C. The temperature of the unreacted fuel gas is 90℃ when it leaves the hot water heat exchanger. The production indicators are shown in Table 4. Calculated based on 8,760 hours/year, the megawatt-level solid oxide fuel cell has generated a total of 8.06 million kilowatt-hours of electricity, calculated at 0.5 yuan/degree, with an income of 4.03 million yuan, and co-produced 4,420 tons of medium-pressure steam and 4,350 tons of low-pressure steam, respectively at 200 yuan / ton, 150 yuan / ton, the revenue is 884,000 yuan, 653,000 yuan, the total revenue is 5.567 million yuan, steam revenue accounts for 27.6%.

Table 4 Production index value of 2MW (low calorific value) hydrogen-containing fuel gas intake such as industrial exhaust gas and refinery exhaust gas

Example 5: When the hydrogen content of hydrogen-containing fuel gas such as industrial exhaust gas and refinery exhaust gas is 10%, the temperature of the fuel gas entering the solid oxide fuel cell SOFC anode after purification and preheating is 600°C, and the anode exhaust gas after reaction The temperature is 680℃. The pressure of the newly injected fresh oxygen is 3MPa, and the cathode exhaust gas entering the cathode exhaust gas storage tank is pressurized by the supercharger to a pressure of 1.5MPa. The temperature of the cathode reactants entering the solid oxide fuel cell is 600°C, and the temperature of the cathode exhaust gas after the reaction is 700°C. The temperature of the anode exhaust gas leaving the production medium-pressure steam heat exchanger is 350°C, and the temperature leaving the production low-pressure steam heat exchanger is 160°C. The temperature of the cathode exhaust gas leaving the production medium-pressure steam heat exchanger is 380°C, and the temperature leaving the production low-pressure steam heat exchanger is 380°C. The temperature of the unreacted fuel gas is 95℃ when it leaves the hot water heat exchanger. The production indicators are shown in Table 5. Calculated based on 8,760 hours/year, the megawatt solid oxide fuel cell has generated a total of 6.13 million kilowatt-hours of electricity, calculated at 0.5 yuan/degree, with an income of 3.065 million yuan, and co-produced 4,815 tons of medium-pressure steam and 4,750 tons of low-pressure steam, each calculated at 200 yuan / ton, 150 yuan / ton, the revenue is 963,000 yuan, 713,000 yuan, the total revenue is 4.741 million yuan, steam revenue accounts for 35.4%.

Table 5 Production index value of 2MW (low calorific value) hydrogen-containing fuel gas intake such as industrial exhaust gas and refinery exhaust gas

It can be seen from the comprehensive examples 1 to 5 that: during the entire process of co-generation of steam, when the hydrogen content of the initial fuel gas is not less than 30%; the pressure of the newly injected oxygen in the cathode tail gas storage tank is not higher than 4MPa; the cathode tail gas After being pressurized by the compressor, the pressure is not higher than 2MPa; the first preset temperature of the fuel gas entering the fuel cell anode after preheating is not lower than 700°C; after the first medium-pressure steam is produced from the anode tail gas, its temperature Not lower than 400°C. After the first low-pressure steam is produced, its temperature is not lower than 200°C. The second preset temperature of the oxygen entering the fuel cell cathode after preheating is not lower than 700°C; after the cathode tail gas produces the second medium-pressure steam, the temperature is not lower than 400°C; after the second low-pressure steam is produced, the temperature is not lower than 700°C. below 150℃. In the entire power generation process, the total revenue generated by the cogeneration steam system's power generation and the total tonnage of medium-pressure steam and low-pressure steam produced is higher than the total revenue when fuel gas, oxygen and other related parameters are not within the preset range. Therefore, setting the relevant parameters of the process flow according to the range of fuel gas and oxygen related parameter setting requirements can better improve the efficiency of cogeneration and obtain better revenue effects.

The co-generation steam system in the power generation process of the embodiment of the present invention combines fuel cell combustion power generation with steam production. Compared with the traditional method of steam production through combustion, it reduces carbon dioxide emissions during the steam production process and simultaneously utilizes The anode exhaust gas and cathode exhaust gas of the fuel cell produce steam, which improves the waste heat quality of the anode exhaust gas and cathode exhaust gas and brings better economic benefits.

It is understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary approach. Based on design preferences, it is understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy described.

In the foregoing detailed description, various features are grouped together in single embodiments to simplify the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, this invention lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby expressly incorporated into the Detailed Description, with each claim standing on its own as a separate preferred embodiment of this invention.

The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for describing the above embodiments, but those of ordinary skill in the art will recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the description or claims, the word is encompassed in a manner similar to the term "comprises" as if "comprises" were to be interpreted as a linking word in the claims. Furthermore, any term "or" used in the description of the claims is intended to mean "a non-exclusive or".

Claims (15)

1. A system for co-generating steam during power generation, which includes: a fuel cell, a gas supply unit, an oxygen supply unit, and a first steam generation unit and/or a second steam generation unit;

   The gas supply unit is connected to the anode of the fuel cell to provide fuel gas for the fuel cell;

   The oxygen supply unit is connected to the cathode of the fuel cell to provide oxygen to the fuel cell;

   The fuel cell is used to generate electricity using the fuel gas and the oxygen and produce anode exhaust gas and cathode exhaust gas;

   A first steam generation unit, connected to the anode, is used to generate steam by exchanging heat with water between the anode exhaust gas generated by the anode;

   The second steam generation unit is connected to the cathode and is used to generate steam by exchanging heat with water between the cathode exhaust gas generated by the cathode.
2. The system according to claim 1, wherein the air supply unit includes: a purifier and an air supply preheating device;

   The purifier is used to treat impurities in the initial fuel gas;

   The air supply preheating device includes a first heat exchanger and a second heat exchanger, the first heat exchanger is connected to the purifier, and the second heat exchanger is connected to the fuel cell; The gas supply preheating device is used to preheat the treated fuel gas so that the fuel gas reaches the first preset temperature and is supplied to the anode of the fuel cell.
3. The system according to claim 1, wherein the oxygen supply unit includes: a cathode exhaust gas storage tank, a compressor and an oxygen supply preheating device;

   The cathode tail gas storage tank is connected to the second steam generation unit and is used to store the cathode tail gas and/or newly injected oxygen, and mix the cathode tail gas and the newly injected oxygen to obtain mixed oxygen, and the cathode tail gas is not yet reacting oxygen;

   The compressor is connected to the cathode tail gas storage tank and is used to compress the cathode tail gas, newly injected oxygen or mixed oxygen to reach a preset pressure;

   The oxygen supply preheating device is used to preheat the compressed cathode tail gas, newly injected oxygen or mixed oxygen to reach the second preset temperature.
4. The system of claim 1, wherein,

   The first steam generation unit includes a third heat exchanger and a fourth heat exchanger. The third heat exchanger is connected to the anode of the fuel cell to use the anode exhaust gas and water to exchange heat to produce the first medium pressure steam. , the fourth heat exchanger is connected to the third heat exchanger to use the anode exhaust gas and water to exchange heat to produce the first low-pressure steam;

   The second steam generation unit includes a fifth heat exchanger and a sixth heat exchanger. The fifth heat exchanger is connected to the cathode of the fuel cell to generate second medium-pressure steam using cathode exhaust gas. The sixth heat exchanger The heat exchanger is connected to the fifth heat exchanger to produce second low-pressure steam using the cathode exhaust gas.
5. The system of claim 4, further comprising a third steam generation unit,

   The third steam generation unit includes a positive gas tail gas burner, a seventh heat exchanger, an eighth heat exchanger and a ninth heat exchanger;

   The positive gas tail gas burner is connected to the fourth heat exchanger for burning unreacted fuel gas in the anode tail gas to produce combustion products, and the positive gas tail gas burner is connected to an oxygen supply preheating device and a second heat exchanger. The heater is connected to allow the combustion products to preheat the fuel gas and oxygen;

   The seventh heat exchanger is connected to the second heat exchanger and the oxygen supply preheating device to produce third medium-pressure steam by exchanging heat between the preheated combustion products and water;

   The eighth heat exchanger is connected to the seventh heat exchanger to utilize combustion products and water to exchange heat to produce third low-pressure steam;

   The ninth heat exchanger is connected to the eighth heat exchanger to produce hot water and vent combustion products.
6. The system of claim 5, wherein the eighth heat exchanger is connected to the first heat exchanger to preheat the fuel gas using third low pressure steam.
7. A method for co-generating steam in a power generation process, which includes: using the system for co-generating steam in a power generation process as claimed in any one of claims 1 to 6 to produce steam, the steps of which are as follows:

   The gas supply unit provides fuel gas for the anode of the fuel cell, and the oxygen supply unit provides oxygen for the cathode of the fuel cell;

   Utilize the fuel gas and oxygen to perform a power generation reaction in a fuel cell and generate anode exhaust gas and cathode exhaust gas;

   The first steam generation unit uses the anode tail gas and water to exchange heat to produce steam, and/or the second steam generation unit uses the cathode tail gas and water to exchange heat to produce steam.
8. The method of claim 7, wherein the gas supply unit provides fuel gas for the anode of the fuel cell, comprising:

   The gas supply unit purifies and preheats the initial fuel gas so that the fuel gas reaches a first preset temperature and is supplied to the anode of the fuel cell for reaction.
9. The method of claim 8, wherein the oxygen supply unit provides oxygen to the cathode of the fuel cell, comprising:

   The oxygen supply unit compresses and preheats the newly injected oxygen, the cathode tail gas, or the mixed oxygen of the newly injected oxygen and the cathode tail gas, so that it reaches the preset pressure and the second preset temperature, and then provides it to the fuel The reaction takes place at the cathode of the battery.
10. The method of claim 7, wherein the first steam generation unit utilizes the anode exhaust gas and water to exchange heat to produce steam, and/or the second steam generation unit utilizes the cathode exhaust gas and water to exchange heat Produces steam including:

    The first steam generation unit uses the anode tail gas to perform heat exchange in the third heat exchanger and the fourth heat exchanger to produce first medium pressure steam and first low pressure steam;

    The second steam generation unit uses the cathode exhaust gas to perform heat exchange in the fifth heat exchanger and the sixth heat exchanger to produce second medium pressure steam and second low pressure steam.
11. The method of claim 7, further comprising:

    The third steam generation unit uses the combustion products of the unreacted fuel gas to perform heat exchange in the seventh heat exchanger, the eighth heat exchanger and the ninth heat exchanger to produce third medium pressure steam, third Low pressure steam and hot water.
12. The method of claim 11, wherein,

    The third low-pressure steam preheats the fuel gas;

    The combustion products of the unreacted fuel gas are preheated for the fuel gas and the oxygen.
13. The method of claim 9, wherein the hydrogen content of the initial fuel gas is not less than 30%;

    The pressure of newly injected oxygen in the cathode tail gas storage tank is not higher than 4MPa;

    After the cathode exhaust gas is pressurized by the compressor, the pressure is not higher than 2MPa.
14. The method of claim 8, wherein the first preset temperature of the fuel gas entering the fuel cell anode after preheating is not lower than 700°C; after the anode exhaust gas produces the first medium-pressure steam, its temperature Not lower than 400°C. After the first low-pressure steam is produced, its temperature is not lower than 200°C.
15. The method of claim 9, wherein,

    The second preset temperature of the oxygen entering the fuel cell cathode after preheating is not lower than 700°C; after the cathode tail gas produces the second medium-pressure steam, the temperature is not lower than 400°C; after the second low-pressure steam is produced, the temperature is not lower than 700°C. Below 150℃.

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