Pre-combustion reinforced biomass and coal co-combustion device

Abstract

The invention relates to a biomass and coal co-combustion device, in particular to a pre-combustion reinforced biomass and coal co-combustion device. The invention aims to solve the problem that the existing coal and biomass co-combustion device has obvious'wind grabbing 'and is difficult to be effectively applied to a coal-fired industrial boiler. The pre-combustion decoupling treatment is carried out on the biomass fuel, and the pre-combustion gas and the pre-combustion coke participate in the initial combustion process and the later burnout process of the pulverized coal in stages. Firstly, pre-combustion gas enters a combustion chamber to be mixed with coal for combustion. The pre-combustion gas is combusted to quickly ignite the pulverized coal, stable ignition of the pulverized coal is powerfully guaranteed, the amount of air needed by the pre-combustion gas in the combustion process is relatively small, the problem of wind robbing is relieved, and then a gas-solid mixture formed after the pre-combustion gas and the pulverized coal are combusted flows out of the combustion chamber and enters the second-stage combustion hearth. And meanwhile, the pre-burning coke also enters the second-stage combustion hearth and participates in the subsequent combustion process of the gas-solid mixture. The invention belongs to the technical field of solid fuel combustion.

Description

Technical Field

[0001] The invention relates to a biomass and coal mixed combustion device, in particular to a pre-combustion enhanced biomass and coal mixed combustion device, belonging to the technical field of solid fuel combustion. Background Art

[0002] In recent years, high-intensity coal combustion has caused atmospheric CO2 concentrations to soar, triggering environmental crises such as global warming and frequent extreme weather events, posing a severe challenge to human sustainable development. Among the many emission reduction technology paths, the co-firing of biomass in coal-fired boilers has attracted considerable attention as a key low-carbon transformation technology. my country has abundant biomass resources, with the annual output of agricultural and forestry biomass alone reaching 2.34 billion tons. Currently, the low-carbon transformation of power plant boilers has achieved phased results. With the deepening implementation of the dual-carbon strategy, the low-carbon transformation of coal-fired industrial boilers will inevitably become a key area of ​​focus in the future. Industrial pulverized coal boilers, as a type of coal-fired industrial boiler, have the advantages of low pollutant emissions and a high degree of automation. Achieving technological breakthroughs in the efficient co-firing of biomass is of great significance to promoting green and low-carbon development in the industrial sector.

[0003] In existing coal and biomass mixed combustion devices, for example, the invention patent with publication number CN118935372A uses a thick-light separation technology to delay the biomass combustion flame and reduce the risk of burn damage or even flashback at the burner nozzle. However, when a large proportion of biomass is mixed and burned, coal and biomass enter the furnace through the same burner. Since biomass has a high volatile content and is flammable, while coal has a low volatile content and is relatively difficult to burn. In the initial stage of combustion, biomass can ignite quickly and ignite coal powder, which is conducive to stable combustion to a certain extent. However, this process has an obvious "wind rush problem." Because biomass will quickly consume a large amount of oxygen when burning, the residence time of coal in an environment with sufficient oxygen is greatly shortened, which is not conducive to the complete combustion of coal powder.

[0004] Another example is the invention patent with the publication number CN109990267B, which proposes a low NO x The core process of the emission technology solution is as follows: the biomass is first pyrolyzed in the pyrolysis device, and the pre-combustion gas generated is mixed with pulverized coal and burned in the main combustion zone of the furnace through an independent gas burner; the coke remaining after pyrolysis is transported to the reburning zone of the boiler for secondary combustion. This technical solution has three significant features: first, the gas burner and the pulverized coal burner are designed to be separated. The flame generated by the gas burner usually ignites the pulverized coal from the downstream to ensure the stable operation of the combustion system; second, in order to achieve efficient reduction of NO xFirst, pyrolysis coke is fed into the reburning zone above the main combustion zone, which requires ample furnace space to ensure complete combustion of the coke. Third, the heat required for biomass pyrolysis relies on the high-temperature flue gas generated by the coal-fired boiler. Therefore, this technical solution demonstrates excellent adaptability to large-scale coal-fired power plant boilers, enabling efficient synergistic combustion of biomass and pulverized coal.

[0005] However, this technical solution presents significant compatibility issues when applied to coal-fired industrial boilers. First, coal-fired industrial boilers generally operate with frequent starts and stops and large load fluctuations, placing extremely high demands on combustion stability. The aforementioned method of igniting pulverized coal from downstream with a gas burner is not conducive to stable combustion and cannot meet the rapid operational response requirements of industrial boilers. Second, due to the compact furnace space and short fuel residence time of industrial boilers, the solution of feeding pyrolysis coke into the reburning zone exacerbates the problem of incomplete combustion of biomass coke. Furthermore, ensuring complete combustion requires a long furnace stroke. Finally, compared to the high-load, high-temperature combustion conditions of large power plant boilers, coal-fired industrial boilers are primarily used for heating, with low heat loads and limited flue gas volumes. Using some of the flue gas heat for biomass pyrolysis would significantly impact the boiler's overall thermal efficiency and operational stability. Therefore, this technology is more suitable for large coal-fired power plant boilers and is difficult to effectively apply to coal-fired industrial boilers with low heat loads and limited space.

[0006] In summary, in order to achieve full combustion of both fuels when biomass is mixed with coal-fired industrial boilers, a new biomass and coal mixed combustion device is proposed, which has become an urgent problem to be solved by technicians in this field. Summary of the Invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides a pre-combustion-enhanced biomass and coal mixed combustion device.

[0008] The technical solution of the present invention is: a pre-combustion enhanced biomass and coal mixed combustion device, including a biomass feeding pipe, a first secondary air duct, a first pre-combustion furnace, a cyclone separator, a pre-combustion gas pipe, a pre-combustion coke pipe, a blunt body, a pulverized coal primary air duct, a second secondary air duct, a combustion chamber and a secondary combustion furnace.

[0009] The biomass feeding pipe and the first and second air ducts are both connected to the lower part of the first-stage pre-combustion furnace, and the outlet of the first-stage pre-combustion furnace is connected to the feed port on the side wall of the cyclone separator.

[0010] The exhaust port at the top of the cyclone separator is connected to the pre-combustion gas pipeline, and the discharge port at the bottom of the cyclone separator is connected to the pre-combustion coke pipeline.

[0011] A blower is installed at one end of the pre-coking pipe, and the other end of the pre-coking pipe is connected to the secondary combustion furnace.

[0012] The pre-gas pipeline, the pulverized coal primary air pipeline and the second secondary air pipeline are all connected to the inlet of the combustion chamber, and the pre-gas pipeline is coaxially arranged with the combustion chamber. A blunt body is installed in the pre-gas pipeline. The pulverized coal primary air pipeline is coaxially sleeved on the pre-gas pipeline, and the second secondary air pipeline is coaxially sleeved on the pulverized coal primary air pipeline.

[0013] The combustion chamber is coaxially installed at the entrance of the secondary combustion furnace.

[0014] Compared with the prior art, the present invention has the following effects:

[0015] 1. The pre-gas' main components include carbon monoxide, methane, hydrogen, and carbon dioxide, making it highly flammable. When the pre-gas and pulverized coal are fed into combustion chamber 10, the pre-gas ignites first. The resulting high-temperature flame directly heats the pulverized coal airflow from the combustion source, significantly shortening the ignition delay of the pulverized coal and effectively meeting the operational requirements of coal-fired industrial boilers, which frequently start and stop and experience rapid load fluctuations. Furthermore, the pre-gas requires relatively little air for combustion. During the combustion reaction within combustion chamber 10, only a small amount of air is consumed, effectively allocating most of the air to the pulverized coal combustion. This alleviates the "wind rush" problem in existing technologies, maximizes the time the pulverized coal remains in an oxygen-rich environment, and creates favorable conditions for relatively complete combustion of the pulverized coal within the combustion chamber.

[0016] 2. The biomass fuel is pre-combusted in the primary pre-combustion furnace 3, partially burning the carbon in the biomass. The pre-burned char formed during the pre-combustion process carries the remaining carbonaceous components into the secondary combustion furnace 11 for further combustion. This staged combustion method promotes the complete burnout of the biomass fuel by extending the effective residence time of the fuel in the furnace. It successfully overcomes the long burnout time required by existing technologies due to the introduction of biomass pyrolysis char from the reburning zone. It is well-suited to the structural characteristics of coal-fired industrial boilers, which have short fuel travel and limited reaction space.

[0017] In addition, the pre-combustion combustion process of biomass in the first-level pre-combustion furnace 3 releases heat, which is different from the heat absorption of biomass thermal decomposition in the existing technology. It avoids the energy consumption mode that relies on the flue gas of coal-fired boilers to provide heat, reduces the disturbance of the original thermal system of the boiler during the process of co-firing biomass in coal-fired industrial boilers, helps to maintain the stability of the overall operating performance of the boiler, and improves the energy utilization efficiency and operating economy of the biomass and coal co-combustion system.

[0018] In summary, for the blending of biomass into coal-fired industrial boilers, the present invention can not only ensure the stable combustion of pulverized coal, but also effectively promote the complete combustion of the two fuels, thereby improving the combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the present invention;

[0020] In the figure: 1. Biomass feed pipe; 2. First and second air ducts; 3. First-stage pre-combustion furnace; 4. Cyclone separator; 5. Pre-gas pipe; 6. Pre-coke pipe; 7. Blunt body; 8. Pulverized coal primary air duct; 9. Second and second air duct; 10. Combustion chamber; 11. Second-stage combustion furnace. DETAILED DESCRIPTION

[0021] In order to make the objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0022] Specific implementation method 1: Combination Figure 1 To illustrate this embodiment, a pre-combustion enhanced biomass and coal co-combustion device of this embodiment includes a biomass feeding pipe 1, a first secondary air duct 2, a first pre-combustion furnace 3, a cyclone separator 4, a pre-combustion gas pipe 5, a pre-combustion coke pipe 6, a blunt body 7, a pulverized coal primary air pipe 8, a second secondary air duct 9, a combustion chamber 10 and a secondary combustion furnace 11.

[0023] The biomass feeding pipe 1 and the first and second air ducts 2 are both connected to the lower part of the first-stage pre-combustion furnace 3 , and the outlet of the first-stage pre-combustion furnace 3 is connected to the feed port on the side wall of the cyclone separator 4 .

[0024] The exhaust port at the top of the cyclone separator 4 is connected to the pre-combustion gas pipeline 5, and the discharge port at the bottom of the cyclone separator 4 is connected to the pre-combustion coke pipeline 6. Furthermore, a discharge baffle is provided at the discharge port, which is arranged at an angle to the horizontal plane, and the windward side of the discharge baffle faces the blower, and the pre-combustion coke is discharged from the leeward side of the discharge baffle to the pre-combustion coke pipeline 6.

[0025] A blower is installed at one end of the pre-coking pipe 6 , and the other end of the pre-coking pipe 6 is communicated with the secondary combustion furnace 11 .

[0026] The pre-gas pipeline 5, the pulverized coal primary air pipeline 8 and the second secondary air pipeline 9 are all connected to the inlet of the combustion chamber 10. The pre-gas pipeline 5 is coaxially arranged with the combustion chamber 10. A blunt body 7 is installed in the pre-gas pipeline 5. The pulverized coal primary air pipeline 8 is coaxially sleeved on the pre-gas pipeline 5, and the second secondary air pipeline 9 is coaxially sleeved on the pulverized coal primary air pipeline 8.

[0027] The combustion chamber 10 is coaxially mounted at the entrance of the secondary combustion furnace 11 .

[0028] Specific implementation method 2: Combination Figure 1 To explain this embodiment, in this embodiment, the bluff body 7 is a cylindrical bluff body, and the bluff body 7 is coaxially arranged with the combustion chamber 10 .

[0029] Other components and connection relationships are the same as those in the first embodiment.

[0030] Specific implementation method three: Combination Figure 1 To illustrate this embodiment, in this embodiment, the first secondary air duct 2 is a DC secondary air duct. Preferably, the first secondary air duct 2 provides combustion air through a Roots blower.

[0031] Furthermore, the second secondary air duct 9 is a swirl secondary air duct. Specifically, a plurality of axial swirl blades are installed at the outlet of the second secondary air duct 9 in a circular array. Preferably, the number of the axial swirl blades is 16 to 32.

[0032] Other components and connection relationships are the same as those in the first or second embodiment.

[0033] Specific implementation method four: Combination Figure 1 To illustrate this embodiment, the first and second air ducts 2 can deliver combustion-supporting air that accounts for 20% to 50% of the theoretical air volume required for complete combustion of the biomass fuel in the primary pre-combustion furnace 3 .

[0034] Furthermore, the combustion-supporting air that can be delivered by the pulverized coal primary air duct 8 and the second secondary air duct 9 accounts for 50% to 100% of the air required for the complete combustion of the two fuels, biomass and pulverized coal, in the secondary combustion furnace 11 .

[0035] Other components and connection relationships are the same as those in the first, second or third embodiment.

[0036] Specific implementation method five: Combination Figure 1 To illustrate this embodiment, a plurality of axial swirl blades are installed at the outlet of the pre-gas pipe 5 in a circular array. Other components and connection relationships are the same as those of the first, second, third or fourth embodiments.

[0037] Specific implementation method six: combination Figure 1 In this embodiment, the cyclone separator 4 is an adiabatic air separator. Other components and connection relationships are the same as those in the first, second, third, fourth or fifth embodiment.

[0038] How it works

[0039] The present invention decouples precombustion of biomass fuel, allowing the pre-combustion gas and pre-burned char to participate in the initial combustion and later burnout of pulverized coal in stages. During normal operation, biomass pre-combusts under oxygen-depleted conditions within the primary pre-combustion furnace 3, generating pre-combustion gas and pre-burned char. The pre-combustion gas, primarily composed of carbon monoxide, methane, hydrogen, and carbon dioxide, exhibits excellent flammability. The pre-burned char has a unique, well-developed pore structure and excellent combustion characteristics.

[0040] The pre-gas enters the combustion chamber 10 through the exhaust port at the top of the cyclone separator 4 and the pre-gas pipeline 5, where it mixes with the pulverized coal for combustion. Due to its flammable nature, the pre-gas quickly ignites the pulverized coal, effectively ensuring stable ignition of the coal. Crucially, the pre-gas requires relatively little air during combustion. During the combustion reaction in the combustion chamber 10, the pre-gas consumes only a small amount of air, allowing the majority of the air to be allocated to the pulverized coal combustion. This alleviates the "air rush" problem that occurs in traditional combustion processes, maximizes the time the pulverized coal remains in an oxygen-rich environment, and creates favorable conditions for more complete combustion of the coal in the combustion chamber.

[0041] Subsequently, the gas-solid mixture formed after the combustion of the pre-combustion gas and the pulverized coal flows out of the combustion chamber and enters the secondary combustion furnace 11 for further combustion; at the same time, the pre-burned coke is sent into the secondary combustion furnace 11 through the discharge port at the bottom of the cyclone separator 4 and the pre-burned coke pipe 6, and participates in the subsequent combustion process of the gas-solid mixture, thereby promoting the further combustion of the two fuels.

[0042] The present invention has been disclosed as above in terms of preferred embodiments, but this is not intended to limit the present invention. Any simple modifications, equivalent changes, and modifications made to the above implementation cases by any person skilled in the art without departing from the content of the technical solution of the present invention based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A pre-combustion enhanced biomass and coal co-combustion device, characterized by: It includes a biomass feed pipe (1), a first secondary air duct (2), a first pre-combustion furnace (3), a cyclone separator (4), a pre-combustion gas duct (5), a pre-coke duct (6), a blunt body (7), a pulverized coal primary air duct (8), a second secondary air duct (9), a combustion chamber (10) and a second-stage combustion furnace (11); The biomass feed pipe (1) and the first and second air ducts (2) are both connected to the lower part of the first-stage pre-combustion furnace (3), and the outlet of the first-stage pre-combustion furnace (3) is connected to the feed port on the side wall of the cyclone separator (4); the exhaust port on the top of the cyclone separator (4) is connected to the pre-combustion gas pipeline (5), and the discharge port at the bottom of the cyclone separator (4) is connected to the pre-combustion coke pipeline (6); A blower is installed at one end of the pre-coking pipe (6), and the other end of the pre-coking pipe (6) is connected to the secondary combustion furnace (11); The pre-gas pipeline (5), the pulverized coal primary air pipeline (8) and the second secondary air pipeline (9) are all connected to the inlet of the combustion chamber (10), and the pre-gas pipeline (5) and the combustion chamber (10) are coaxially arranged, a blunt body (7) is installed in the pre-gas pipeline (5), the pulverized coal primary air pipeline (8) is coaxially sleeved on the pre-gas pipeline (5), and the second secondary air pipeline (9) is coaxially sleeved on the pulverized coal primary air pipeline (8); The combustion chamber (10) is coaxially mounted at the entrance of the secondary combustion furnace (11).

2. The pre-combustion enhanced biomass and coal co-combustion device according to claim 1, characterized in that: The bluff body (7) is a cylindrical bluff body.

3. The pre-combustion enhanced biomass and coal mixed combustion device according to claim 2, characterized in that: The first and second air ducts (2) are direct current secondary air ducts.

4. The pre-combustion enhanced biomass and coal co-firing device according to claim 1, characterized in that: The first and second air ducts (2) provide combustion air via a Roots blower.

5. The pre-combustion enhanced biomass and coal co-firing device according to claim 4, characterized in that: The combustion-supporting air that can be transported by the first and second air ducts (2) accounts for 20% to 50% of the theoretical air volume required for complete combustion of the biomass fuel in the first-stage pre-combustion furnace (3).

6. The pre-combustion enhanced biomass and coal co-firing device according to claim 2, characterized in that: The pulverized coal primary air duct (8) and the second secondary air duct (9) can transport combustion-supporting air that accounts for 50% to 100% of the air required for complete combustion of the coal and biomass fuels in the secondary combustion furnace (11).

7. The pre-combustion enhanced biomass and coal co-firing device according to claim 1, characterized in that: The second secondary air duct (9) is a cyclone secondary air duct.

8. The pre-combustion enhanced biomass and coal co-firing device according to claim 1, characterized in that: A plurality of axial swirl blades are installed at the outlet of the pre-gas pipeline (5) in a circular array.

9. The pre-combustion enhanced biomass and coal co-firing device according to claim 1, characterized in that: A plurality of axial swirl blades are installed at the outlet of the second secondary air duct (9) in a circular array.

10. The pre-combustion enhanced biomass and coal co-firing device according to claim 1, characterized in that: The cyclone separator (4) is an adiabatic air separator.

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