A method and system for mixed combustion

Abstract

The present application relates to the technical fields of combustion system, and discloses a mixed combustion method and system, the mixed combustion method comprising S1: a dosing system measures and mixes fossil energy fuel and biomass charcoal, and a raw material is obtained by proportioning; S2: a fuel grinding device is used to grind the raw material, and the fuel of different calorific values after processing is respectively stored in a separate storage system; S3: all the storage systems simultaneously supply fuel to a burner mixed fuel supply system, and the mixed fuel supply system of the burner adjusts the proportioning according to the required calorific value fuel of the corresponding burner, and the final fuel is obtained. By proportioning and mixing the biomass charcoal and coal or other fuels, the use amount of raw coal or other raw materials is reduced, by the method of proportioning and mixing fuels of different calorific values, the required fuel type of different areas in the kiln can be adjusted conveniently, and each parameter raw material does not need to be processed separately, so that the cost is reduced and the control is convenient.

Description

Technical Field

[0001] This invention relates to the technical field of combustion systems, specifically to a method and system for mixed combustion. Background Technology

[0002] This project promotes the utilization of biomass charcoal powder, a product of biomass pyrolysis carbonization furnaces, in high-pollution and high-energy-consuming industries, serving as a substitute for traditional fossil fuels such as raw coal, heavy oil, and natural gas. Biomass energy is a renewable energy source.

[0003] Currently, high-energy-consuming and high-polluting industries, such as the cement and glass manufacturing industries, primarily use three major fossil fuels: coal, heavy oil, and natural gas. These industries consume large quantities of these non-renewable energy sources during production, causing significant environmental impact. Reducing the use of fossil fuels is crucial, and biomass energy, as a renewable energy source, is a superior fuel alternative in these energy-intensive and high-polluting industries.

[0004] Biomass materials, such as straw, sawdust, pecan shells, bagasse, and rice husks, are highly polluting fuels when directly burned, with low thermal energy utilization rates. Their use is currently prohibited in Chinese cities. The biomass pyrolysis carbonization furnace moves the pulverized biomass material through a carbonization reaction tube and a carbonization propulsion screw within the carbonization chamber, sequentially passing through a preheating zone, a preliminary pyrolysis zone, a complete pyrolysis zone, and a carbonization zone. By controlling the temperature and oxygen supply within the carbonization chamber, the biomass material undergoes continuous and uninterrupted pyrolysis and carbonization over a short distance. Throughout the entire biomass pyrolysis and carbonization process, the carbonization chamber utilizes the combustible pyrolysis gases released during the biomass pyrolysis reaction to generate heat, heating the carbonization reaction tubes. Only a small amount of heat is provided in the preheating zone; no additional fuel is consumed in other areas. The waste gas generated during the entire carbonization and pyrolysis process meets direct emission standards. The high-temperature hot flue gas emitted can be recovered and utilized through a heat recovery system.

[0005] Biomass char produced by biomass pyrolysis carbonization furnaces has a calorific value of approximately 3700-7600 kcal / kg (the calorific value varies depending on the biomass material used), and low moisture content. In contrast, the calorific value of coal used in cement (glass) production lines is approximately 7000 kcal / kg, and that of heavy oil is approximately 9000 kcal / kg. Biomass char has a low sulfur content; the dry basis sulfur content of biomass char produced from various biomass materials is ≤0.1%, which avoids the environmental pollution problems caused by the combustion of coal and heavy oil, reducing its environmental impact. Biomass char produced by biomass pyrolysis carbonization furnaces has a small particle size and low density, which facilitates complete combustion in the combustion chamber of industrial kilns. The raw material cost for biomass char is low, and a large amount of agricultural and forestry solid waste needs to be treated and disposed of each year, thus achieving both economic and social benefits.

[0006] However, due to the low calorific value of biochar, it is difficult to achieve the required kiln temperature using only biochar. Therefore, currently, biochar is generally mixed with raw coal or other fuels. The mixing ratio of biochar with raw coal or other fuels is generally related to the combustion position in the kiln, ensuring that the kiln temperature meets the standard while achieving energy conservation and emission reduction. For example, the required temperatures differ between the head and tail of a cement kiln, and different areas within a glass kiln require different fuel ratios. This generally necessitates the addition of a coal mill, leading to increased equipment and control costs. Furthermore, during the firing process, the kiln temperature needs to be controlled. When the temperature exceeds the set value, it is lowered, and vice versa. Traditionally, this is adjusted by controlling the fuel supply. Sudden changes in the fuel supply cause significant fluctuations in control parameters, which is detrimental to the stable operation of the equipment. This application addresses these issues. Summary of the Invention

[0007] The purpose of this invention is to provide a mixing combustion method and system to overcome the problem of inconvenience in adjusting the fuel ratio of burners in different zones in traditional combustion systems.

[0008] This invention is achieved through the following technical solution.

[0009] A method for mixed combustion according to the present invention includes the following steps:

[0010] S1: The batching system measures and mixes fossil fuels and biochar to produce the raw materials;

[0011] S2: The above raw materials are ground using fuel grinding equipment, and the processed fuels with different calorific values ​​are stored in separate storage systems.

[0012] S3: All storage systems simultaneously supply fuel to the burner's mixed fuel supply system, which adjusts the ratio of fuel according to the calorific value required by its corresponding burner to obtain the final fuel.

[0013] S4: The burner mixing fuel supply system supplies the proportioned fuel to the burner for combustion.

[0014] Furthermore, prior to step S1, the required fuel is statistically analyzed to determine the required highest calorific value fuel and lowest calorific value raw material.

[0015] In step S1, the batching system proportions the raw materials according to the medium-calorific-value fuel, which is between the highest-calorific-value fuel and the lowest-calorific-value feedstock.

[0016] In step S2, the fuel grinding equipment grinds the above raw materials to obtain mixed fuel. The mixed fuel is then passed through a fuel sorting system so that the fuel entering different storage systems has different calorific values.

[0017] The calorific value detection module detects the calorific value parameters of the blended fuel / final fuel, and the blended fuel supply system refers to this parameter when adjusting the fuel ratio.

[0018] Furthermore, it also includes the following steps:

[0019] When the kiln temperature needs to be adjusted, the following temperature adjustment steps are performed:

[0020] Increase the temperature: Increase the proportion of the highest calorific value fuel in the final fuel;

[0021] Lowering the temperature: Increase the proportion of the lowest calorific value fuel in the final fuel.

[0022] Furthermore, during the temperature regulation process, the total fuel supply to the burner remains unchanged or changes gradually when the temperature is increased or decreased.

[0023] Furthermore, during the temperature regulation process, the total fuel supply to the burner gradually changes when the temperature is increased or decreased.

[0024] Furthermore, it also includes an emission gas monitoring step: the exhaust gas monitoring system monitors pollutants in the emitted flue gas, and when the pollution level is detected to be lower than the set value, the proportion of the highest calorific value fuel in the final fuel is increased; when the pollution level is detected to be higher than the set value, the proportion of the lowest calorific value fuel in the final fuel is increased.

[0025] A hybrid combustion system, based on the above-mentioned hybrid combustion method, is characterized by comprising a batching system, a fuel grinding system, a storage system, a hybrid fuel supply system, and a fuel sorting system. The batching system is used to meter biochar and fossil fuels. The fuel grinding system is used to grind the metered and mixed biochar and fossil fuels. The fuel sorting system connects the fuel grinding system and the storage system. The storage system includes at least two storage tanks, each storing fuels with different calorific values. Several hybrid fuel supply systems are provided, and each hybrid fuel supply system is connected to all the storage tanks.

[0026] Furthermore, the hybrid combustion system also includes a calorific value detection module.

[0027] Furthermore, the hybrid combustion system also includes an exhaust gas monitoring system, which is electrically connected to the hybrid fuel supply system.

[0028] Furthermore, the hybrid combustion system also includes a fuel supply system.

[0029] The beneficial effects of this invention are:

[0030] By blending biochar with coal or other fuels in a specific ratio, the amount of raw coal or other raw materials used is reduced, which can reduce the consumption of fossil energy and reduce emissions of sulfides and nitrogen oxides. At the same time, by blending fuels with different calorific values, it is easy to adjust the fuel type required for different areas of the kiln without having to process each raw material separately for each parameter, which reduces costs and makes control convenient. Furthermore, when adjusting the temperature inside the kiln, the fuel ratio can be controlled to avoid instability in the system's operating state caused by large fluctuations in the fuel supply.

[0031] By setting up a fuel sorting system, the fuel grinding system and batching system can maintain a stable working state without the need for time-based parameter adjustments, further reducing the difficulty of control. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the hybrid combustion system of the present invention;

[0035] Figure 2 This is a schematic diagram of the overall structure of the hybrid combustion system in Embodiment 2;

[0036] Figure 3 This is a schematic diagram of the fuel sorting system. Detailed Implementation

[0037] The following is combined with Figures 1-3 The present invention will be described in detail below. Example

[0038] A method for mixed combustion according to the present invention includes the following steps:

[0039] S1: Statistically analyze the required fuel calorific value range for each burner to determine the lowest and highest calorific value fuels. For example, in the production of glass and cement, several small furnaces or burners are distributed in the kiln. There may be temperature differences between some areas. Based on the required different temperatures and the optimal fuel supply, the optimal fuel calorific value required by the burners in the corresponding areas can be determined. The calorific value fuel parameters required by all burners are summarized to determine the lowest and highest calorific value fuels.

[0040] S2: The batching system measures and mixes fossil fuels such as raw coal and petroleum coke powder with biochar. In this embodiment, raw coal is preferred. The raw materials for the lowest calorific value fuel and the highest calorific value fuel are respectively proportioned. Specifically, the raw material supply system 5 delivers the two raw materials to two metering devices, weighs the appropriate amount of raw materials, and proportions the lowest calorific value fuel and the highest calorific value fuel respectively. Biochar has a high carbon content and a fast combustion speed. After adding coal powder, the flame shape and temperature distribution in the kiln are guaranteed.

[0041] S3: The proportioned raw materials are fed into the fuel grinding equipment, which is generally a coal mill. The raw materials are ground and processed by the fuel grinding equipment to fully mix the biochar and coal. The processed fuels are stored in separate storage systems to obtain primary mixed fuels. The two fuels are processed in a cycle.

[0042] S4: All storage systems simultaneously supply fuel to the burner's mixed fuel supply system. The burner's mixed fuel supply system adjusts the proportion of fuel according to the calorific value required by its corresponding burner to obtain the final fuel. Specifically, when the burner requires the lowest calorific value fuel, the mixed fuel supply system only obtains the lowest calorific value fuel and then supplies it to the burner for combustion. When the burner requires the highest calorific value fuel, the mixed fuel supply system only obtains the highest calorific value fuel and then supplies it to the burner for combustion. When the burner requires fuel with a calorific value between the lowest and highest calorific value fuel parameters, the mixed fuel supply system obtains the lowest and highest calorific value fuels in proportion and then mixes them to obtain the final fuel. This allows for the adjustment of fuel parameters based on the required temperature, flame length, firing zone position (cement kiln), and other kiln operating data in different areas of the kiln. The initial mixing of the fuel only requires the proportioning of two fuel parameters.

[0043] S5: The burner mixing fuel supply system supplies the proportioned fuel to the burner for combustion.

[0044] Preferably, the method further includes the following steps:

[0045] When the kiln temperature needs to be adjusted, the following temperature adjustment steps are performed:

[0046] Increase the temperature: Increase the proportion of the highest calorific value fuel in the final fuel;

[0047] Lowering the temperature: Increase the proportion of the lowest calorific value fuel in the final fuel.

[0048] The proportion adjustment can be done gradually, rather than all at once.

[0049] Optionally, during the temperature regulation step, the fuel supply can be changed in two ways. One way is that when the temperature is raised or lowered, the total fuel supply to the burner remains unchanged. This way, the control parameters of the combustion system, i.e., the operating status, will not fluctuate due to changes in the fuel supply.

[0050] Another approach is to gradually increase the fuel supply to the burner when the temperature is increased and gradually decrease the fuel supply when the temperature is decreased. This approach will cause slight fluctuations, which will have a smaller impact on the system's operating status compared to traditional sudden fluctuations, while also enabling rapid temperature regulation.

[0051] Preferably, the system also includes an emission gas monitoring step: the exhaust gas monitoring system monitors pollutants in the exhaust gas. When the pollution level is detected to be lower than the set value, the proportion of the highest calorific value fuel in the final fuel is increased, and the fuel supply is reduced. When the pollution level is detected to be higher than the set value, the proportion of the lowest calorific value fuel in the final fuel is increased, and the fuel supply is increased. This ensures that the sulfides and nitrogen oxides in the exhaust gas emissions meet the emission requirements at each time period as much as possible. When the pollution level is detected to be lower than the set value, the system can also reduce costs. Example

[0052] The difference from Example 1 is:

[0053] S1: Statistically analyze the required fuels to determine the highest calorific value fuel and the lowest calorific value raw material; the batching system proportions the raw materials based on the medium calorific value fuel, which falls between the highest and lowest calorific value fuels; the batching system measures and mixes fossil fuels and biochar to produce the required raw materials; optionally, since the calorific value parameters of each batch of raw materials may vary, the calorific value of the raw materials needs to be manually tested before this step to obtain the calorific value parameters.

[0054] S2: After the fuel grinding equipment grinds the above raw materials, it obtains mixed fuel. The mixed fuel passes through the fuel sorting system, which adjusts the proportion of internal components of the fuel through air classification, centrifugation and other methods, so that the calorific value of the fuel entering the storage in different storage systems is different.

[0055] S3: All storage systems simultaneously supply fuel to the burner's mixed fuel supply system. The calorific value detection module detects the calorific value parameter of the mixed fuel / final fuel at the burner. When the mixed fuel supply system adjusts the fuel ratio, it refers to this parameter. The burner's mixed fuel supply system adjusts the ratio according to the calorific value fuel required by its corresponding burner, as well as the above calorific value parameter and other parameters, to obtain the final fuel.

[0056] S4: The burner mixing fuel supply system supplies the proportioned fuel to the burner for combustion.

[0057] This embodiment does not require processing and mixing multiple fuels, so the fuel grinding equipment and batching system can maintain stable control parameters.

[0058] An embodiment of a mixed combustion system, based on the mixed combustion method in Embodiment 1 or 2 above, includes a control system, a batching system 1, a fuel grinding system 2, a storage system 3, and a mixed fuel supply system 4. The batching system 1 is used to meter biochar and coal, and includes a raw coal metering system 11 and a biochar metering system 12. The fuel grinding system 2 is used to grind the metered and mixed biochar and coal. At least one set of fuel grinding system 2 can be set, and multiple sets can be set. The storage system 3 includes at least two storage tanks, namely storage tank 1 31 and storage tank 2 32, each of which stores fuels with different calorific values. Several mixed fuel supply systems 4 are set, and each mixed fuel supply system 4 is connected to all storage tanks.

[0059] Specifically, the above system can be applied in glass production, cement production, steelmaking production, and other production processes that require temperature control in different areas of the kiln. The control system generally uses a computer to control and adjust the parameters of each system. This combustion system can be connected to the kiln temperature monitoring and control system. The fuel ratio can be automatically adjusted according to temperature changes and the required adjustment amount. The mixed fuel supply system 4 generally includes a metering valve 41 (such as a pulverized coal flow valve), a mixer 42, and a fuel powder supply pipeline connected to each mixed fuel supply system 4. The mixed fuel supply system 4 supplies the proportioned fuel to the burner.

[0060] Preferably, the biochar and coal co-combustion system further includes an exhaust gas monitoring system, which is electrically connected to the co-fuel supply system 4.

[0061] Optionally, a fuel storage monitoring component is installed in the storage tank. This component is electrically connected to the fuel grinding system 2. The fuel storage monitoring component can be implemented using a three-dimensional pressure sensor, image recognition component, etc., to monitor the remaining fuel level in the storage tank in real time. When the fuel level is lower than a set value, a signal is sent to the control system. The control system then controls the batching system 1 and the fuel grinding system 2 to grind the corresponding fuel. When the fuel levels in both storage tanks are simultaneously lower than the set value, the control system determines which tank has higher fuel consumption and prioritizes processing the higher-consumption fuel. Optionally, more than one fuel grinding system 2 can be installed.

[0062] Optionally, the hybrid combustion system also includes a raw material supply system 5, which may include conveying equipment such as conveyor belts for transporting raw materials from the warehouse to the batching system 1.

[0063] Preferably, the storage tank is equipped with a stirring mechanism.

[0064] A second embodiment of the hybrid combustion system: In the first embodiment, due to the high cost and large footprint of the large fuel grinding system 2, when a set of fuel grinding systems 2 is set up, it is necessary to grind fuels with different proportions at different times. At the same time, the batching system 1 needs to make corresponding adjustments and adjust the fuel grinding time according to different fuel consumption rates, resulting in an increased workload. In this embodiment, such as Figure 2 , Figure 3 A fuel sorting system 6 is added, which connects the fuel grinding system 2 and the storage system 3. The fuel grinding system 2 and the batching system 1 maintain constant operating parameters for most of the time, processing only medium-calorific-value fuels with proportions between their highest and lowest calorific values. After the medium-calorific-value fuels are mixed and ground, they enter the fuel sorting system 6. The fuel sorting system 6 can employ methods such as air separation, vibration separation, and centrifugal separation. In this embodiment, the fuel sorting system 6 includes a duct 61 and a feed inlet 62. A fan is installed at one end of the duct 61, which is connected to storage tanks 31 and 32 in the storage system 3. The biomass char and pulverized coal are partially separated due to their different densities, meaning the resulting fuel is still a blended fuel, but with different cost ratios. This results in different ratios of biomass char and pulverized coal entering the fuel in different storage tanks, leading to fuels with different calorific values. Through this method, the fuel grinding system 2 and the batching system 1 do not need to adjust parameters in a timely manner, maintaining a stable working state. Furthermore, a calorific value detection module (such as a thermometer or calorimeter) is installed at the burner to detect the specific calorific value parameters of the blended fuel. The control system adjusts the fuel ratio at different blended fuel supply systems 4 based on the real-time detection parameters.

[0065] When different calorific values ​​of premixed fuels are required, only the blower power needs to be changed, and there is still no need to adjust the fuel grinding system 2 and the batching system 1.

[0066] The feed inlet 62 and the inlets of storage tanks 31 and 32 are not limited to... Figure 3 Due to the limited positional relationship, for example, the feed inlet 62 can be set near the inlet of the storage tank 31.

[0067] A third embodiment of the hybrid combustion system: Based on any of the above embodiments of the hybrid combustion system, an additional storage tank three is added. Storage tank three is used to store the powdered biochar. When the fuel calorific value demand is low, only the biochar can be fed into the burner and used for combustion alone.

[0068] A third embodiment of the mixed combustion system: Based on any of the above embodiments, a biomass char grinding device is added. The biomass char grinding device is connected to the batching system 1 and the mixed fuel supply system 4. When biomass char needs to be used for combustion alone, the biomass char is ground through the biomass char grinding device. Since the fuel grinding system 2 needs to grind the raw coal and has a large power, the separately set biomass char grinding device can be a small-power fast grinding device.

[0069] The fourth embodiment of the mixed combustion system: Based on the mixed combustion system in the first embodiment, the fuel grinding system 2 is directly connected to the mixed fuel supply system 4. When it is necessary to burn pulverized coal or biochar separately, the fuel grinding system 2 can grind the corresponding fuel and supply it directly to the mixed fuel supply system 4.

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand and implement the present invention. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A hybrid combustion method, characterized by: It comprises the following steps: S1: the batching system measures and mixes fossil energy fuel and biomass charcoal, and the raw materials are proportioned; S2: the fuel grinding equipment is used to grind the above-mentioned raw materials, and the processed fuels of different calorific values are respectively stored in separate storage systems; S3: all storage systems simultaneously supply fuel to the burner mixed fuel supply system, and the burner mixed fuel supply system adjusts the proportion of the required calorific value fuel for the corresponding burner to obtain the final fuel; S4: the burner mixed fuel supply system supplies the proportioned fuel to the burner for combustion; Before S1, the required fuel is counted to obtain the highest calorific value fuel and the lowest calorific value raw material; In S1, the batching system proportionally adjusts the raw materials according to the medium calorific value fuel between the highest calorific value fuel and the lowest calorific value raw material; In S2, after the fuel grinding equipment grinds the above-mentioned raw materials, the mixed fuel is obtained, and the fuel with different calorific values stored in different storage systems is obtained through the fuel sorting system; The calorific value detection module detects the calorific value parameters of the mixed fuel / final fuel, and the mixed fuel supply system adjusts the fuel proportioning according to the parameters.

2. The hybrid combustion method of claim 1, wherein: It also comprises the following steps: When the temperature in the kiln needs to be adjusted, the temperature adjustment step is performed: Increase the temperature: increase the proportion of the highest calorific value fuel in the final fuel; Lower the temperature: increase the proportion of the lowest calorific value fuel in the final fuel.

3. The hybrid combustion method of claim 2, wherein: In the temperature adjustment step, when the temperature is increased and decreased, the total fuel supply amount of the burner remains unchanged or gradually changes.

4. The mixed combustion method according to any one of claims 1 to 3, characterized by: It also includes an exhaust gas monitoring step: the exhaust gas monitoring system monitors the pollutants in the exhaust gas, and when the pollution level is lower than the set value, the proportion of the highest calorific value fuel in the final fuel is increased; when the pollution level is higher than the set value, the proportion of the lowest calorific value fuel in the final fuel is increased.

5. A hybrid combustion system based on the hybrid combustion method according to any one of claims 1 to 4, characterized in that: It comprises a batching system (1), a fuel grinding system (2), a storage system (3), a mixed fuel supply system (4) and a fuel sorting system (6), the batching system (1) is used to measure biomass charcoal and fossil energy fuel, the fuel grinding system (2) is used to grind the measured and mixed biomass charcoal and fossil energy fuel, the fuel sorting system (6) is connected to the fuel grinding system (2) and the storage system (3), the storage system (3) comprises at least two storage tanks, each storage tank stores fuel with different calorific values, and the mixed fuel supply system (4) is provided with a plurality of mixed fuel supply systems (4), each mixed fuel supply system (4) is connected to all storage tanks.

6. The hybrid combustion system of claim 5, wherein: The mixed combustion system also comprises a calorific value detection module.

7. The hybrid combustion system of claim 5 or 6, wherein: The mixed combustion system also comprises an exhaust gas monitoring system, which is electrically connected to the mixed fuel supply system (4).

8. The hybrid combustion system of claim 5, wherein: The mixed combustion system also comprises a raw material supply system (5).

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