Biomass gasification combined cooling heating and power supply method and system

Abstract

The invention provides a biomass gasification combined cooling heating and power supply method and system. The biomass gasification combined cooling heating and power supply method comprises the following steps: S1, carrying out gasification reaction on a biomass raw material and water vapor in a gasification furnace to generate high-temperature fuel gas; s2, the high-temperature fuel gas is purified through a fuel gas purification facility, and the purified high-temperature fuel gas is cooled through a waste heat boiler to generate medium-temperature fuel gas and medium-temperature medium-pressure steam; s3, the medium-temperature fuel gas enters a heat exchanger for heat exchange after being pressurized by a supercharger to form low-temperature fuel gas, and heat released by heat exchange heats condensed water and then is fed into a waste heat boiler; s4, the low-temperature fuel gas enters an internal combustion generator set for power generation, and generated high-temperature flue gas enters a waste heat boiler to generate medium-temperature medium-pressure steam; and S5, at least part of medium-temperature medium-pressure steam generated by the waste heat boiler is returned to the gasification furnace for gasification reaction. The comprehensive utilization rate of energy is increased, the operation cost of the system is reduced, and combined supply of cooling, heating and power is achieved.

Description

Technical Field

[0001] The present invention relates to the field of energy technology, and in particular to a biomass gasification combined cooling, heating and power generation method and system. Background Art

[0002] Biomass energy is the energy provided by living plants in nature. These plants use biomass as a medium to store solar energy. Biomass energy has the following characteristics: 1) Rich raw materials: Biomass energy resources are abundant and widely distributed; 2) Renewable: Biomass energy is converted from solar energy. Through the photosynthesis of plants, solar energy is converted into chemical energy. The energy stored in the biomass is a renewable energy source and can achieve sustainable use of energy; 3) Clean and low-carbon: The content of harmful substances in biomass energy is very low. At the same time, the conversion process of biomass energy is to synthesize biomass from carbon dioxide and water through the photosynthesis of green plants. The use process of biomass energy generates carbon dioxide and water, forming a cyclic emission process of carbon dioxide, which can effectively reduce the net emission of carbon dioxide and reduce the greenhouse effect; 4) Alternative advantages: Modern technology can be used to convert biomass energy into biomass molded fuel, biomass combustible gas, biomass liquid fuel, etc. that can replace fossil fuels.

[0003] At present, the use of biomass energy as a renewable energy source has received widespread attention. Biomass gasification is a thermochemical reaction that uses oxygen or oxygen-containing substances in the air as a gasifying agent to convert the combustible part of biomass fuel into combustible gas under high temperature conditions. However, existing biomass gasification technologies mainly use air or oxygen as gasifying agents. Using air as a gasifying agent will result in a high nitrogen content in the gas, reducing the calorific value of the gas, while using oxygen as a gasifying agent will result in a high cost; that is, most of the existing biomass gasification technologies have problems such as low gasification efficiency, poor gas quality, low calorific value, and low comprehensive energy utilization rate.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a biomass gasification combined heat and power method and system, which improves the comprehensive utilization rate of energy, reduces the operating cost of the system, and realizes combined heat and power.

[0006] The present invention provides a biomass gasification combined cooling, heating and power generation method, comprising the following steps:

[0007] S1: gasifying the biomass raw materials and water vapor in a gasifier to generate high-temperature fuel gas;

[0008] S2: Use gas purification facilities to purify high-temperature gas, and the purified high-temperature gas is cooled by waste heat boiler to produce medium-temperature gas and medium-temperature medium-pressure steam;

[0009] S3: The medium-temperature gas is pressurized by the supercharger and then enters the heat exchanger to form low-temperature gas. The heat released by the heat exchange heats the condensed water and is then sent to the waste heat boiler.

[0010] S4: Low-temperature fuel gas enters the internal combustion generator set to generate electricity, and the generated high-temperature flue gas enters the waste heat boiler to generate medium-temperature and medium-pressure steam;

[0011] S5: At least part of the medium-temperature and medium-pressure steam generated by the waste heat boiler is returned to the gasifier for gasification reaction.

[0012] In step S1, there is no strict restriction on the biomass raw materials used, and biomass raw materials such as straw, husk, and waste wood can be used; in one embodiment, the biomass raw materials can include the following raw materials in parts by weight: 20-30 parts of rice straw, 20-30 parts of wheat straw, and 40-60 parts of forestry waste.

[0013] The temperature of the gasification reaction is 800-1000℃, the pressure is 0.1-0.3MPa, and the gasification reaction time is 30s-5min; the temperature of the high-temperature fuel gas generated by the gasification reaction is 700-800℃, and the flow rate is 10000-15000kJ / Nm 3 , calorific value is 8-10MJ / m 3 The composition of high temperature fuel gas includes (volume content): CO 25-35%, H2 20-30%, CO2 10-20%, hydrocarbon (C m H n )2-10%, and the rest is N2 and other gases. The gasification effect of using water vapor as a gasifying agent is good, which improves the gasification efficiency and cleanliness of biomass. The quality and calorific value of the generated high-temperature fuel gas are high, which is conducive to improving the subsequent power generation efficiency.

[0014] In step S2, the purification of high-temperature fuel gas includes dust removal and oil removal. The temperature of the purified high-temperature fuel gas is reduced by 40-60°C; the purified high-temperature fuel gas is cooled by the waste heat boiler to produce medium-temperature fuel gas with a temperature of 100-200°C; the temperature of the generated medium-temperature and medium-pressure steam is 195-200°C and the pressure is 1.25-1.30MPa.

[0015] In step S3, the temperature of the medium-temperature gas is 410-430°C; the medium-temperature gas is pressurized to 0.2-0.25MPa by a supercharger; and the temperature of the low-temperature gas formed by heat exchange in a heat exchanger is 80-100°C.

[0016] In step S4, the high-temperature flue gas enters the waste heat boiler to generate medium-temperature and medium-pressure steam with a temperature of 195-200°C and a pressure of 1.25-1.30 MPa.

[0017] In step S5, at least part of the medium-temperature and medium-pressure steam generated by the waste heat boiler is returned to the gasifier for gasification reaction; at the same time, the remaining medium-temperature and medium-pressure steam generated by the waste heat boiler is sent to the lithium bromide absorption refrigeration unit for cooling in summer, and is sent to the heating equipment for heating in winter, and is supplied as industrial steam to the outside during the rest of the time.

[0018] The present invention also provides a biomass gasification combined heat and power supply system, which is used for the above-mentioned biomass gasification combined heat and power supply method. The biomass gasification combined heat and power supply system includes a gasifier, a gas purification facility, a first waste heat boiler, a booster, a heat exchanger, an internal combustion generator set and a second waste heat boiler arranged in sequence, and the steam outlets of the first waste heat boiler and the second waste heat boiler are connected to the gasifier.

[0019] Furthermore, the steam outlets of the first waste heat boiler and the second waste heat boiler are also connected to the lithium bromide absorption refrigeration unit and the heating equipment.

[0020] The biomass gasification combined heat and power method and system of the present invention utilizes water vapor as a gasifying agent, thereby improving the gasification efficiency and cleanliness of biomass, and achieving high gas quality and calorific value; at the same time, the comprehensive utilization rate of energy is improved by using heat recovery technology, and the heat of high-temperature fuel gas and high-temperature flue gas is recovered, and the produced steam is returned to the gasifier as a gasifying agent, thereby reducing the operating cost of the system; in particular, the above method and system realize combined heat and power, can provide users with a stable supply of electricity and heat and cold, reduce environmental pollution, and comply with the green and environmentally friendly energy development direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The process flow chart of the biomass gasification combined cooling, heating and power generation method of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the biomass gasification combined cooling, heating and power system of the present invention.

[0024] Description of reference numerals:

[0025] 1: Gasification furnace; 2: Gas purification facilities; 3: First waste heat boiler; 4: Booster compressor; 5: Heat exchanger; 6: Internal combustion generator set; 7: Second waste heat boiler; 8: Lithium bromide absorption refrigeration unit; 9: Heating equipment. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1 As shown, the biomass gasification combined cooling, heating and power generation method of this embodiment includes the following steps:

[0031] S1: Gasification reaction

[0032] Rice straw, wheat straw and forestry waste are uniformly mixed in a mass ratio of 25:25:50 to obtain a biomass raw material.

[0033] The above biomass raw materials and water vapor are sent to a gasifier (10t / h) for gasification reaction. The temperature during the gasification reaction is 900℃, the pressure is 0.2MPa, and the gasification reaction time is 60s. After the gasification reaction, high-temperature fuel gas is generated. The temperature of the high-temperature fuel gas is 750℃ and the flow rate is 15000kJ / Nm 3 , calorific value is 10MJ / m 3 ; The composition of high-temperature fuel gas is (volume content): CO30%, H2 25%, CO2 20%, hydrocarbon 2%, and the rest is N2 and other gases.

[0034] S2: Purification and cooling

[0035] The high-temperature fuel gas generated after the gasification reaction is sent to the fuel gas purification facility for dust and oil removal. The temperature of the high-temperature fuel gas after purification is 700°C.

[0036] The purified high-temperature fuel gas is sent to the first waste heat boiler (5t / h) for cooling to produce medium-temperature fuel gas and medium-temperature medium-pressure steam. The temperature of the medium-temperature fuel gas is 410°C, and the temperature of the medium-temperature medium-pressure steam is 200°C and the pressure is 1.25MPa.

[0037] S3: pressurization, heat exchange

[0038] The medium-temperature gas generated by the cooling of the first waste heat boiler is pressurized to 0.2MPa by the booster and then enters the heat exchanger for heat exchange to form low-temperature gas. The temperature of the low-temperature gas is 90°C; the heat released by the heat exchange heats the condensed water and is then sent to the waste heat boiler (including the first waste heat boiler and the second waste heat boiler).

[0039] S4: Power Generation

[0040] The low-temperature fuel gas formed by heat exchange in the heat exchanger enters the internal combustion generator set (14MW) to generate electricity, and the high-temperature flue gas generated enters the second waste heat boiler (4t / h) to generate medium-temperature and medium-pressure steam. The temperature of the medium-temperature and medium-pressure steam is 200℃ and the pressure is 1.25MPa.

[0041] S5: Steam Utilization

[0042] At least part of the medium-temperature and medium-pressure steam generated by the first waste heat boiler and the second waste heat boiler is returned to the gasifier for gasification reaction; in addition, the remaining medium-temperature and medium-pressure steam generated by the waste heat boiler is sent to the lithium bromide absorption refrigeration unit (6MW) for cooling in summer, with a cooling area of ​​50,000 m 2 In winter, it is sent to heating equipment for heating, with a heating area of ​​70,000 m 2 . During the rest of the time, it is used as industrial steam for external supply.

[0043] The gasification efficiency of the conventional gasifier using air as the oxidant is 70%, and the biomass direct combustion power generation efficiency is 25%; while the biomass gasification combined heat and power generation method of this embodiment has a gasification efficiency of 85%, a power generation efficiency of 37%, and a combined heat and power generation efficiency of 71%.

[0044] Example 2

[0045] like Figure 2 As shown, this embodiment provides a biomass gasification combined heat and power system, including a gasifier 1, a gas purification facility 2, a first waste heat boiler 3, a booster 4, a heat exchanger 5, an internal combustion generator set 6 and a second waste heat boiler 7 which are arranged in sequence, and the steam outlets of the first waste heat boiler 3 and the second waste heat boiler 7 are connected to the gasifier 1; in addition, the steam outlets of the first waste heat boiler 3 and the second waste heat boiler 7 are also connected to a lithium bromide absorption refrigeration unit 8 and a heating device 9.

[0046] The working process of the biomass gasification combined cooling, heating and power system of this embodiment is as follows:

[0047] The biomass raw materials and water vapor (from the first waste heat boiler 3 and the second waste heat boiler 7) are gasified in the gasifier 1. The high-temperature gas generated by the gasification is purified by the gas purification facility 2 for dust removal and oil removal and then enters the first waste heat boiler 3 to produce medium-temperature gas and medium-temperature medium-pressure steam. The medium-temperature gas after cooling is pressurized by the gas booster 4 and then sent to the heat exchanger 5 to continue to release heat. The released heat heats the condensed water as boiler feed water and is sent to the first waste heat boiler 3 and the second waste heat boiler 7. The low-temperature gas formed by heat exchange in the heat exchanger 5 finally enters the internal combustion generator set 6 to generate electricity, and the discharged high-temperature flue gas enters the second waste heat boiler 7 to continue to produce medium-temperature medium-pressure steam. The medium-temperature medium-pressure steam generated by the first waste heat boiler 3 and the second waste heat boiler 7 is returned to the gasifier 1 as a gasifying agent. At the same time, the remaining medium-temperature medium-pressure steam can be used for cooling by the lithium bromide absorption refrigeration unit 8 in summer and for heating by the heating equipment 9 in winter, and can be used as industrial steam for external supply in other periods.

[0048] The biomass gasification combined heat and power method and system of the present embodiment utilizes water vapor as a gasifying agent, thereby improving the gasification efficiency and cleanliness of biomass, and achieving high gas quality and calorific value; at the same time, the comprehensive utilization rate of energy is improved by using heat recovery technology, and the heat of high-temperature fuel gas and high-temperature flue gas is recovered, and the produced steam is returned to the gasifier 1 as a gasifying agent, thereby reducing the operating cost of the system; in particular, the above method and system realize combined heat and power, can provide users with a stable supply of electricity and heat and cold, reduce environmental pollution, and comply with the green and environmentally friendly energy development direction.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biomass gasification combined cooling, heating and power generation method, characterized in that: The steps include: S1: gasifying the biomass raw materials and water vapor in a gasifier to generate high-temperature fuel gas; S2: Use gas purification facilities to purify high-temperature gas, and the purified high-temperature gas is cooled by waste heat boiler to produce medium-temperature gas and medium-temperature medium-pressure steam; S3: The medium-temperature gas is pressurized by the supercharger and then enters the heat exchanger to form low-temperature gas. The heat released by the heat exchange heats the condensed water and is then sent to the waste heat boiler; S4: Low-temperature fuel gas enters the internal combustion generator set to generate electricity, and the generated high-temperature flue gas enters the waste heat boiler to generate medium-temperature and medium-pressure steam; S5: At least part of the medium-temperature and medium-pressure steam generated by the waste heat boiler is returned to the gasifier for gasification reaction.

2. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The remaining medium-temperature and medium-pressure steam generated by the waste heat boiler is sent to the lithium bromide absorption refrigeration unit for cooling in summer, sent to the heating equipment for heating in winter, and supplied as industrial steam in the rest of the time.

3. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The biomass raw materials include the following raw materials in parts by weight: 20-30 parts of rice straw, 20-30 parts of wheat straw and 40-60 parts of forestry waste.

4. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The temperature during the gasification reaction is 800-1000°C, the pressure is 0.1-0.3MPa, and the gasification reaction time is 30s-5min.

5. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The temperature of high temperature gas is 700-800℃ and the flow rate is 10000-15000kJ / Nm 3 , calorific value is 8-10MJ / m 3 .

6. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The composition of high temperature fuel gas includes: CO 25-35%, H2 20-30%, CO2 10-20%, hydrocarbon 2-10%, and the rest is N2 and other gases.

7. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The temperature of the medium-temperature gas is 410-430°C; the medium-temperature gas is pressurized to 0.2-0.25MPa; the temperature of the low-temperature gas is 80-100°C.

8. The biomass gasification combined cooling, heating and power method according to claim 1, characterized in that: The temperature of medium-temperature and medium-pressure steam is 195-200°C and the pressure is 1.25-1.30MPa.

9. A biomass gasification combined cooling, heating and power system, characterized in that: The biomass gasification combined heat and power method for supplying heat and power as described in any one of claims 1 to 8, the biomass gasification combined heat and power system comprises a gasifier, a gas purification facility, a first waste heat boiler, a booster, a heat exchanger, an internal combustion generator set and a second waste heat boiler arranged in sequence, and the steam outlets of the first waste heat boiler and the second waste heat boiler are connected to the gasifier.

10. The biomass gasification combined cooling, heating and power system according to claim 9, characterized in that: The steam outlets of the first waste heat boiler and the second waste heat boiler are also connected to the lithium bromide absorption refrigeration unit and the heating equipment.

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