Automatic control system for temperature and feeding time of gasification combustion of biomass briquette fuel

Abstract

The biomass briquette gasification combustion temperature and feeding time automatic control system comprises a feeding area, a gasification area, a fuel gas pre-combustion area, a boiler body, a temperature monitoring module, a feeding system, an oxygen increasing system and an automatic control module, the gasification area is communicated with the feeding area, the feeding system is connected with the feeding area and the gasification area and is used for conveying the biomass particle fuel to the gasification area, the gasification area is used for carrying out the oxygen-deficient thermal cracking on the biomass particle to generate combustible gas and unburned fixed carbon, a carbon residue discharging mechanism is arranged at the bottom of the gasification area, the fuel gas pre-combustion area is communicated with the gasification area, the boiler body is communicated with the fuel gas pre-combustion area, and the boiler body receives the fuel gas type flame output heat energy. The particulate matter generated in the combustion cannot be blown into the smoke exhaust channel, the particulate matter in the flue gas is extremely low, the oxygen supply flow is accurate when the combustible gas starts to combust for the second time, the combustion is sufficient, the oxygen content of the flue gas is greatly reduced, and the formation of nitrogen oxides is reduced.

Description

Technical Field

[0001] This utility model relates to the fields of energy and energy conservation and emission reduction technology, and in particular to an automatic control system and method for temperature and feeding time of biomass briquette gasification combustion. Background Technology

[0002] Traditional biomass combustion technologies are mainly divided into two categories: stoker combustion and low-temperature anaerobic pyrolysis. Both have significant drawbacks. In stoker combustion, biomass pellets or wood chips are directly laid on the boiler grate and forced to burn by a blower. Because the volatiles in the biomass fuel are not completely decomposed before combustion, combustion is incomplete. Furthermore, the grate is prone to coking and the heating tubes are prone to ash accumulation after use. Traditional stoker combustion boilers have an energy efficiency of about 82% when they leave the factory, but this drops rapidly to below 75% after a few days. Moreover, the blower's oxygenation blows the particulate matter produced by combustion into the flue, resulting in a high concentration of particulate matter in the flue gas. At the same time, the oxygen supply cannot be precisely controlled, resulting in a high oxygen content in the flue gas, which catalyzes the formation of nitrogen oxides, making it difficult to meet environmental emission standards. Low-temperature anaerobic pyrolysis combustion, under low-temperature conditions, results in incomplete volatilization and pyrolysis, producing a large amount of tar. The tar enters the boiler flue gas duct and heating tube along with the combustible gas, easily condensing and depositing, causing duct blockage, and even damaging the boiler chain grate due to tar carbon buildup, seriously affecting the equipment life. Moreover, the combustible gas generated by low-temperature pyrolysis has a low concentration and unstable composition, resulting in low combustion thermal efficiency, which cannot meet the needs of industrial thermal power or centralized heating.

[0003] However, neither the stoker combustion mode nor the low-temperature anaerobic pyrolysis mode has solved the three core problems of tar blockage, low energy efficiency, and flue gas pollution, and thus cannot achieve efficient, energy-saving, and clean utilization of biomass fuel. Summary of the Invention

[0004] This invention aims to address the shortcomings of existing technologies by providing an automatic control system and method for the temperature and feeding time of high-temperature gasification combustion of biomass.

[0005] To achieve the above objectives, this utility model adopts the following technical solution:

[0006] The automatic control system for temperature and feeding time in biomass pellet fuel gasification and combustion includes a feeding zone, a gasification zone, a gas pre-combustion zone, a boiler body, a temperature monitoring module, a feeding system, an oxygenation system, and an automatic control module. The gasification zone is connected to the feeding zone, and the feeding system connects the feeding zone and the gasification zone to transport biomass pellet fuel to the gasification zone. The gasification zone performs high-temperature, oxygen-deficient pyrolysis on the biomass pellets to generate combustible gas and unburned fixed char. A char discharge mechanism is installed at the bottom of the gasification zone. The gas pre-combustion zone is connected to the gasification zone, where combustible gas is received, ignited by an open flame, and then passed through the oxygenation system. The system precisely controls the oxygen supply to ensure complete combustion of combustible gas, forming a gas-fired flame. The boiler body is connected to the gas pre-combustion zone, and the boiler body receives the heat energy output from the gas-fired flame. The temperature monitoring module includes a temperature sensor 1 located in the middle of the gasification zone to monitor the pyrolysis temperature, a temperature sensor 2 located at the junction of the gas pre-combustion zone and the boiler body to monitor the combustion temperature, and temperature sensors located in the front and rear combustion chambers of the boiler body. The oxygen supply system is connected to the gas pre-combustion zone. The automatic control module includes a controller, which is electrically connected to the temperature monitoring module, the feeding system, and the oxygen supply system.

[0007] The thermal decomposition temperature range of the gasification zone is 635℃~640℃, which allows the volatiles in the biomass fuel to be fully decomposed.

[0008] The combustion temperature range of the gas pre-combustion zone is controlled between 680℃ and 700℃, and the tar and wood vinegar are also burned, effectively solving the above-mentioned defects.

[0009] The biomass fuel contains 75% to 77% volatile matter and 16% to 18% fixed carbon. The fixed carbon has an ignition temperature higher than 630°C. After being discharged from the carbon residue discharge mechanism, the fixed carbon is used to process charcoal rods or activated carbon.

[0010] An open flame ignition device is installed at the end of the gas pre-combustion zone.

[0011] The oxygen supply flow rate of the oxygenation system is slightly adjusted based on the temperature signal of the gas pre-combustion zone and the oxygen content of the flue gas.

[0012] The feeding system is equipped with a variable frequency motor and a potentiometer, intermediate relay, AC contactor and power supply installed on the variable frequency motor connection circuit.

[0013] The automatic control method for temperature and feeding time in biomass gasification combustion comprises the following steps:

[0014] S1. Feeding and oxygen-deficient pyrolysis: Biomass pellet fuel enters the gasification zone through the feeding system and undergoes pyrolysis at 635℃~640℃ in a natural oxygen-deficient environment without forced aeration, generating combustible gas and unburned fixed carbon.

[0015] S2. Temperature monitoring and signal feedback: Temperature sensor 1 collects the pyrolysis temperature of the gasification zone and the combustion temperature of the gas pre-combustion zone in real time, and transmits the data to the controller;

[0016] S3. Automatic adjustment of feeding time: The controller adjusts the feeding frequency and duration of the feeding system according to the temperature signal of the gasification zone to ensure that the volatiles are fully decomposed;

[0017] S4. Combustible gas combustion and oxygenation control: Combustible gas enters the gas pre-combustion zone and is ignited by an open flame ignition device. The controller adjusts the oxygen supply flow of the oxygenation system according to the temperature signal of the gas pre-combustion zone and the oxygen content of the flue gas, so that the combustion temperature is maintained at 680℃~700℃ and the oxygen content of the flue gas is less than 5%, so as to achieve complete combustion.

[0018] S5. Carbon slag discharge and resource utilization: Fixed carbon is discharged directly from the carbon slag discharge mechanism for further processing.

[0019] In step S4, the oxygen content of the flue gas is collected by an oxygen sensor installed at the outlet of the gas pre-combustion zone, and the controller makes a closed-loop fine adjustment of the oxygenation flow rate based on the data collected by the oxygen sensor.

[0020] The beneficial effects of this invention are as follows: the flue gas produced by this invention is cleaner. During gasification combustion, since there is no blower to increase oxygen at the grate, the particulate matter generated during combustion cannot be blown into the flue gas exhaust channel, resulting in extremely low particulate matter content in the flue gas. At the same time, the oxygen supply flow is precise when the combustible gas starts to burn for the second time, and the combustion is complete, significantly reducing the oxygen content in the flue gas, which is conducive to reducing the formation of nitrogen oxides. The initial emission data is reduced by more than half compared with traditional biomass boilers, which is conducive to achieving ultra-low emission environmental protection indicators. Meanwhile, the energy efficiency of the boiler can be greatly improved. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model;

[0022] In the diagram: 1-Gasification zone; 2-Gas pre-combustion zone; 21-Open flame ignition device; 3-Boiler body; 4-Temperature monitoring module; 41-Temperature sensor one; 42-Temperature sensor two; 5-Coke discharge mechanism; 6-Automatic control module; 7-Feeding system; 8-Oxygenation system; 9-Feeding area;

[0023] The following will describe in detail the embodiments of the utility model with reference to the accompanying drawings. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] The automatic control system for temperature and feeding time of biomass pellet fuel gasification and combustion includes a feeding zone 9, a gasification zone 1, a gas pre-combustion zone 2, a boiler body 3, a temperature monitoring module 4, a feeding system 7, an oxygenation system 8, and an automatic control module 6. The gasification zone 1 is connected to the feeding zone 9. The feeding system 7 connects the feeding zone 9 and the gasification zone 1, and is used to transport biomass pellet fuel to the gasification zone 1. The gasification zone 1 performs high-temperature, oxygen-deficient pyrolysis on the biomass pellets to generate combustible gas and unburned fixed char. A char discharge mechanism 5 is installed at the bottom of the gasification zone 1. The gas pre-combustion zone 2 is connected to the gasification zone 1. The gas pre-combustion zone 2 receives combustible gas, ignites it with an open flame, and then oxygenates it. System 8 precisely controls the oxygen supply to ensure complete combustion of combustible gas, forming a gas-fired flame. Boiler body 3 is connected to gas pre-combustion zone 2, and boiler body 3 receives heat energy output from the gas-fired flame. Temperature monitoring module 4 includes temperature sensor 41, which is located in the middle of gasification zone 1 to monitor the pyrolysis temperature, and temperature sensor 42, which is located at the connection between gas pre-combustion zone 2 and boiler body 3 to monitor the combustion temperature. Temperature sensors are also located in the front and rear combustion chambers of the furnace of boiler body 3. Oxygen supply system 8 is connected to gas pre-combustion zone 2. Automatic control module 6 includes a controller, which is electrically connected to temperature monitoring module 4, feeding system 7, and oxygen supply system 8.

[0026] The thermal decomposition temperature range of the gasification zone 1 is 635℃~640℃, which allows the volatiles in the biomass fuel to be fully decomposed.

[0027] The combustion temperature range of the gas pre-combustion zone 2 is controlled between 680℃ and 700℃, and the tar and wood vinegar are also burned, effectively solving the above-mentioned defects.

[0028] The biomass fuel contains 75%–77% volatile matter and 16%–18% fixed char. The fixed char has an ignition temperature higher than 630°C. After being discharged from the char slag discharge mechanism 5, the fixed char is used to process charcoal briquettes or activated carbon. The fixed char does not burn during the initial oxygen-deficient combustion process. Therefore, this part of the char adopts a cooling and extinguishing mode and is directly discharged from the grate under the gasification zone 1 of the first combustion zone. There is no flue gas or solid waste generated during the formation of charcoal slag. It can be further processed into charcoal briquettes for barbecue or activated carbon.

[0029] An open flame ignition device 21 is provided at the end of the gas pre-combustion zone 2.

[0030] The oxygen supply flow rate of the oxygenation system 8 is adjusted according to the temperature signal of the gas pre-combustion zone 2 and the oxygen content of the flue gas.

[0031] The feeding system 7 is equipped with a variable frequency motor and a potentiometer, intermediate relay, AC contactor and power supply installed on the variable frequency motor connection circuit.

[0032] The automatic control method for temperature and feeding time in biomass gasification combustion comprises the following steps:

[0033] S1. Feeding and oxygen-deficient pyrolysis: Biomass pellet fuel enters the gasification zone 1 through the feeding system 7 and undergoes pyrolysis at 635℃~640℃ in a natural oxygen-deficient environment without forced aeration, generating combustible gas and unburned fixed carbon.

[0034] S2. Temperature monitoring and signal feedback: Temperature sensor 41 collects the pyrolysis temperature of gasification zone 1 and the combustion temperature of gas pre-combustion zone 2 in real time and transmits the data to the controller;

[0035] S3. Automatic adjustment of feeding time: The controller adjusts the feeding frequency and duration of the feeding system 7 according to the temperature signal of the gasification zone 1 to ensure that the volatiles are fully decomposed. The feeding time is adjusted by the controller controlling the potentiometer, intermediate relay and AC contactor in the feeding system 7 to change the impedance and thus change the speed of the feed frequency conversion motor, thereby achieving the adjustment of the feeding amount.

[0036] S4. Combustible gas combustion and oxygenation control: Combustible gas enters the gas pre-combustion zone 2 and is ignited by an open flame ignition device. The controller adjusts the oxygen supply flow of the oxygenation system 8 according to the temperature signal of the gas pre-combustion zone 2 and the oxygen content of the flue gas, so that the combustion temperature is maintained at 680℃~700℃ and the oxygen content of the flue gas is less than 5%, so as to achieve complete combustion.

[0037] S5. Carbon slag discharge and resource utilization: Fixed carbon is directly discharged from carbon slag discharge mechanism 5 for further processing.

[0038] In step S4, the oxygen content of the flue gas is collected by an oxygen sensor installed at the outlet of the gas pre-combustion zone 2, and the controller makes a closed-loop fine adjustment of the oxygenation flow rate based on the data collected by the oxygen sensor.

[0039] Traditional boilers have an energy efficiency of 82% when they leave the factory, but this drops to 75% after a few days of use, with serious coking and ash accumulation. In contrast, biomass pellet fuel high-temperature pyrolysis gasification boilers use a gas-fired boiler body and can achieve an energy efficiency of over 90%.

[0040] During gasification combustion, since there is no blower to increase oxygen at the grate, the ash produced during combustion cannot be blown into the flue, resulting in extremely low particulate matter content in the flue gas.

[0041] Meanwhile, during combustion, the precise oxygen supply and complete combustion of combustible gases significantly reduce the oxygen content in the flue gas, which helps to reduce the formation of nitrogen oxides (NOx). X The initial emissions data are reduced by more than half compared to traditional biomass boilers, which is conducive to the comprehensive treatment of ultra-low emissions.

[0042] In the description of the utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of a utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0044] In utility models, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in the utility model according to the specific circumstances.

[0045] The utility model has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the utility model is not limited to the above-described manner. Any improvements made using the utility model's inventive concept and technical solution, or direct application to other situations without modification, are all within the protection scope of the utility model.

Claims

1. An automatic control system for temperature and feeding time in biomass briquette gasification combustion, characterized in that, The system includes a feeding zone (9), a gasification zone (1), a gas pre-combustion zone (2), a boiler body (3), a temperature monitoring module (4), a feeding system (7), an oxygenation system (8), and an automatic control module (6). The gasification zone (1) is connected to the feeding zone (9). The feeding system (7) connects the feeding zone (9) and the gasification zone (1) and is used to transport biomass pellet fuel to the gasification zone (1). The gasification zone (1) performs anaerobic pyrolysis on the biomass pellets to generate combustible gas and unburned fixed char. A char discharge mechanism (5) is set at the bottom of the gasification zone (1). The gas pre-combustion zone (2) is connected to the gasification zone (1). The gas pre-combustion zone (2) receives combustible gas and ignites it with an open flame. Then, the oxygenation is precisely controlled by the oxygenation system (8). The amount of gas is used to fully combust the combustible gas and form a gas-fired flame. The boiler body (3) is connected to the gas pre-combustion zone (2). The boiler body (3) receives the heat energy output by the gas-fired flame. The temperature monitoring module (4) includes a temperature sensor 1 (41) set in the middle of the gasification zone (1) to monitor the thermal decomposition temperature, a temperature sensor 2 (42) set at the connection between the gas pre-combustion zone (2) and the boiler body (3) to monitor the combustion temperature, and temperature sensors set in the front and rear combustion chambers of the furnace of the boiler body (3). The oxygenation system (8) is connected to the gas pre-combustion zone (2). The automatic control module (6) includes a controller. The controller is electrically connected to the temperature monitoring module (4), the feeding system (7), and the oxygenation system (8).

2. The automatic control system for temperature and feeding time of biomass briquette gasification combustion according to claim 1, characterized in that, An open flame ignition device (21) is provided at the end of the gas pre-combustion zone (2).

3. The automatic control system for temperature and feeding time of biomass briquette gasification combustion according to claim 2, characterized in that, The feeding system (7) is equipped with a variable frequency motor and a potentiometer, intermediate relay and AC contactor installed on the variable frequency motor connection circuit.

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