Coal mine cooling and heating power area energy system based on ultralow-concentration gas blending combustion biomass boiler

Abstract

The invention relates to the technical field of coal mine energy resource utilization and energy conservation and environmental protection, and discloses a coal mine cooling, heating and power area energy system based on an ultra-low concentration gas blending combustion biomass boiler, which comprises an ultra-low concentration gas processing module and a biomass boiler module communicated with the ultra-low concentration gas processing module, the steam turbine power generation module is driven by steam generated by the biomass boiler module, and the absorption type refrigeration module receives low-pressure steam exhausted by the steam turbine power generation module to work. The ultralow-concentration gas processing module is used for mixing the extracted gas with the concentration lower than 8% and the air-exhausted gas with the concentration lower than 0.75%. According to the invention, the problem of low utilization efficiency of the ultralow-concentration gas is solved by mixing the ultralow-concentration air exhaust gas and the low-concentration extraction gas and adding the mixture and the biomass into the boiler for blending combustion, and meanwhile, cold and hot energy sources can be provided for a coal mine.

Description

Technical Field

[0001] The present invention relates to the field of coal mine energy resource utilization and energy conservation and environmental protection technology, and in particular to a coal mine cooling, heating and power regional energy system based on an ultra-low concentration gas-blended biomass boiler. Background Art

[0002] The vast majority of my country's coal mines are located in the cold northern regions, creating a huge demand for heat for mine shaft frost protection, heating, and domestic hot water. In recent years, with the advancement of my country's dual carbon strategy, the use of traditional coal-fired boilers in coal mines has been restricted. Many mines have been forced to use gas or electric boilers for heating, but heating costs have skyrocketed. Therefore, coal mines urgently need to find new, low-carbon, and low-cost heating methods. Biomass, as a renewable energy source, is widely available and environmentally friendly. Compared to natural gas boilers, biomass boilers offer significant competitive advantages in heating costs. However, the energy efficiency of biomass boilers currently has significant room for improvement. Furthermore, with the continued development of deep coal mines, the demand for mine cooling is also increasing. Efficiently addressing this issue has become crucial for the safe and sustainable development of coal mines.

[0003] On the other hand, the overall utilization rate of coal mine gas in my country is very low. Based on current technology and market application, over 30% of high-concentration coalbed methane resources can be directly used for internal combustion power generation or concentrated to produce CNG / LNG. The country has banned the direct discharge of this type of gas, and its market utilization rate is close to 100%. For low-concentration gas with a concentration of 8% to 30%, combustion or direct internal combustion power generation technologies are mature, and its market utilization rate is around 70%. With the release of the latest national emission ban standards for this concentration range, its market utilization rate is expected to quickly reach 100%. Meanwhile, extracted gas with a concentration below 8% and exhaust gas with a concentration below 0.75% account for 80% of total coal mine gas emissions. Currently, almost all of this is directly discharged into the air, resulting in extremely low market utilization. This not only wastes resources but also has a significant impact on the atmospheric environment. Therefore, it is the key direction for future coal mine gas utilization.

[0004] Although there are some schemes for burning biomass and low-concentration gas together, such as the Chinese invention patent with document number CN104990092 A, entitled "Ultra-low Concentration Gas Combustion Method and System", and the Chinese invention patent with document number CN116241878A, entitled "A Low-concentration Gas Coupled Biomass Self-excited Oscillation Combustion", these low-concentration gas combustion schemes all use biomass as fuel to ignite ultra-low-concentration gas, which produces high-temperature flue gas. Their combustion is not much different from other gas combustion methods, and there is no new direction for the utilization of their combustion products. Therefore, my country's coal mines are in urgent need of a regional energy system that can fully utilize the ultra-low-concentration gas resources of coal mines and realize a green, low-carbon, and low-cost combined cooling, heating, and power supply system for coal mines. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a coal mine cooling, heating and power regional energy system based on an ultra-low concentration gas-fired biomass boiler. By mixing ultra-low concentration exhaust gas with low concentration extraction gas and adding them together with biomass to the boiler for co-firing, the problem of low utilization efficiency of ultra-low concentration gas is solved, and at the same time, cooling and heating energy can be provided for coal mines.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: a coal mine cooling, heating and power district energy system based on an ultra-low concentration gas-blended biomass boiler, comprising an ultra-low concentration gas treatment module, a biomass boiler module connected to the ultra-low concentration gas treatment module, a steam turbine power generation module driven by steam generated by the biomass boiler module, and an absorption refrigeration module operated by receiving low-pressure steam discharged from the steam turbine power generation module; The ultra-low concentration gas processing module is used to mix the extracted gas with a concentration below 8% with the exhaust gas with a concentration below 0.75%.

[0007] Furthermore, the ultra-low concentration gas processing module includes a mixing device; the biomass boiler module includes a biomass boiler connected to the mixing device through an induced draft duct.

[0008] Furthermore, the biomass boiler uses biomass fuel, and the biomass fuel uses bulk materials or biomass pellets.

[0009] Furthermore, the biomass boiler is provided with a flue gas outlet and is equipped with a dust removal device, a nitrogen oxide removal device and a flue gas waste heat recovery heat exchanger; the flue gas at the flue gas outlet is discharged after passing through the dust removal device, the nitrogen oxide removal device and the flue gas waste heat recovery heat exchanger.

[0010] Furthermore, the ultra-low concentration gas processing module also includes an extraction gas pipeline and an exhaust gas pipeline fixedly connected to the mixing device; the extraction gas pipeline is provided with an extraction gas pipeline flow regulating valve; and the exhaust gas pipeline is provided with an exhaust gas pipeline flow regulating valve.

[0011] Furthermore, the steam turbine power generation module includes a steam turbine and a generator connected to the steam turbine; the air inlet of the steam turbine is fixedly connected to the exhaust port of the biomass boiler to transmit high-temperature and high-pressure steam.

[0012] Furthermore, the absorption refrigeration module includes an absorption refrigeration unit; the turbine exhaust port is respectively connected to the coal mine steam pipeline and the absorption refrigeration unit; the cold water drain port of the absorption refrigeration unit is respectively connected to the building air conditioning terminal heat exchanger and the air inlet wellhead surface cooling heat exchanger; the drain ports of the building air conditioning terminal heat exchanger and the air inlet wellhead surface cooling heat exchanger are respectively connected to the water inlet of the absorption refrigeration unit; the high temperature drain port of the absorption refrigeration unit is connected to the hot water tank.

[0013] Furthermore, a gas concentration sensor is provided at the outlet of the mixing device or on the induced draft duct.

[0014] The beneficial effects of the present invention are: (1) by mixing ultra-low concentration exhaust gas with low concentration extraction gas and adding them together with biomass to the boiler for co-firing, the problem of low utilization efficiency of ultra-low concentration gas is solved, and at the same time, cold and hot energy can be provided for coal mines; resource waste and environmental impact are reduced, which complies with the requirements of the dual carbon policy.

[0015] (2) Improve the thermal efficiency of biomass boilers: The blending of ultra-low concentration gas provides additional heat for biomass boilers, improves combustion conditions, increases the thermal efficiency of biomass boilers, and makes energy utilization more efficient.

[0016] (3) Meeting the green, low-carbon, and low-cost comprehensive energy needs of coal mines: Utilizing biomass, a renewable energy source, combined with the blending of ultra-low-concentration gas reduces the energy procurement costs of coal mines. Biomass boilers are equipped with dust removal and denitrification devices, ensuring that combustion emissions meet environmental standards, reducing pollutant emissions and providing significant environmental benefits.

[0017] (4) Achieving efficient cascade utilization of energy: Through the combined supply of cooling, heating and power, waste heat recovery from boiler flue gas, and the connection of high-temperature condensed water to domestic hot water tanks, efficient cascade utilization of energy is achieved. This meets heating and cooling needs in the heating season and summer, respectively, ensuring the year-round capacity to absorb ultra-low concentration coal mine gas and the stable load operation of biomass boilers throughout the year, thereby improving the efficiency, economy, and reliability of the energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process of the present invention.

[0019] In the figure: 1. Flow regulating valve of gas extraction pipeline; 2. Flow regulating valve of gas exhaust pipeline; 3. Mixing device; 4. Gas concentration sensor; 5. Biomass boiler; 6. Flue gas outlet; 7. Steam turbine; 8. Generator; 9. Coal mine steam pipeline; 10. Absorption refrigeration unit; 11. Building air conditioning terminal heat exchanger; 12. Surface cooling heat exchanger at the air inlet wellhead; 13. Hot water tank. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0021] Directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", "top" and "bottom", are only used with reference to the directions of the drawings. The directional terms used are used to illustrate and understand the present invention, and are not used to limit the present invention.

[0022] Example: like Figure 1 As shown, a coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler combustion includes an ultra-low concentration gas treatment module, a biomass boiler module connected to the ultra-low concentration gas treatment module, a steam turbine power generation module driven by steam generated by the biomass boiler module, and an absorption refrigeration module that receives low-pressure steam discharged from the steam turbine power generation module; The ultra-low concentration gas processing module is used to mix the extracted gas with a concentration below 8% with the exhaust gas with a concentration below 0.75%.

[0023] The ultra-low-concentration gas processing module includes a mixing device 3. The biomass boiler module includes a biomass boiler 5 connected to the mixing device 3 via an induced draft duct. A gas concentration sensor 4 is installed at the outlet of the mixing device 3 or on the induced draft duct to ensure uniform gas mixing. An induced draft fan is installed on the induced draft duct. The induced draft fan delivers the gas to the biomass boiler 5 for mixing with the biomass fuel.

[0024] The biomass boiler 5 uses biomass fuel, and the biomass fuel uses bulk materials or biomass pellets; bulk materials refer to raw biomass raw materials that have not been compressed and are loose in shape, including agricultural and forestry waste such as wood chips, straw fragments, branches, and rice husks; pellets refer to cylindrical solid particles (the size can be 6 to 10 mm in diameter and 10 to 30 mm in length) made by drying, crushing, and high-pressure compression of bulk materials.

[0025] Biomass boiler 5 is equipped with a flue gas outlet 6 and is equipped with a dust removal device, a nitrogen oxide removal device, and a flue gas waste heat recovery heat exchanger. The flue gas at flue gas outlet 6 passes through the dust removal device, nitrogen oxide removal device, and flue gas waste heat recovery heat exchanger before being discharged. The flue gas waste heat recovery heat exchanger is used to exchange heat between the high-temperature, dust-removed flue gas and the boiler feed water, reducing the exhaust gas temperature and increasing the feed water temperature. The waste heat recovery heat exchanger conducts countercurrent heat exchange between the high-temperature, dust-removed flue gas and the boiler feed water (temperature approximately 25°C), reducing the exhaust gas temperature to below 110°C and simultaneously increasing the feed water temperature to approximately 90°C, significantly improving the boiler's thermal efficiency.

[0026] The ultra-low concentration gas processing module also includes an extraction gas pipeline and an exhaust gas pipeline fixedly connected to the mixing device 3; the extraction gas pipeline is provided with an extraction gas pipeline flow regulating valve 1; the exhaust gas pipeline is provided with an exhaust gas pipeline flow regulating valve 2.

[0027] The steam turbine power generation module includes a steam turbine 7 and a generator 8 connected to it. This module can be a back-pressure or extraction steam turbine generator set. The air inlet of the steam turbine 7 is permanently connected to the exhaust of the biomass boiler 5, transmitting high-temperature, high-pressure steam. For example, in a back-pressure generator set, the high-pressure steam (2.5 MPa) generated by the boiler drives the steam turbine, which in turn drives the generator 8 to generate electricity. The exhaust steam (0.15 MPa) from the back-pressure unit is then distributed according to seasonal demand.

[0028] The absorption refrigeration module includes an absorption refrigeration unit 10; the absorption refrigeration unit 10 can be a steam-type lithium bromide chiller or an absorption ice-making unit; the exhaust port of the steam turbine 7 is connected to the coal mine steam pipeline 9 and the absorption refrigeration unit 10 respectively; the low-pressure steam or extracted steam of the steam turbine power generation module is directly connected to the coal mine steam pipeline 9 during the heating season to meet the building heating and wellbore anti-freezing heat load; generally, the exhaust port of the steam turbine 7 is connected to a main pipeline, and the main pipeline is connected to two branch pipelines, which are connected to the coal mine steam pipeline 9 and the absorption refrigeration unit 10 respectively; both branch pipelines are provided with valves that control opening and closing.

[0029] The cold water drain outlet of the absorption refrigeration unit 10 is respectively connected to the building air conditioning terminal heat exchanger 11 and the air inlet wellhead surface cooling heat exchanger 12; the building air conditioning and the full air volume cooling of the mine are realized; the exhaust outlet of the general absorption refrigeration unit 10 is connected to a main pipeline, and the main pipeline is connected to two branch pipelines, and the two branch pipelines are respectively connected to the building air conditioning terminal heat exchanger 11 and the air inlet wellhead surface cooling heat exchanger 12; the two branch pipelines are provided with valves for controlling opening and closing; the drain outlets of the building air conditioning terminal heat exchanger 11 and the air inlet wellhead surface cooling heat exchanger 12 are respectively connected to the water inlet of the absorption refrigeration unit 10, for returning the heated water to the absorption refrigeration unit 10; the high-temperature drain outlet of the absorption refrigeration unit 10 is connected to the hot water tank 13.

[0030] Steam-type lithium bromide chillers generally have six main water inlets and outlets: 1 cooling water inlet: receiving cooling water (higher temperature) from a cooling tower or other cooling water source; 1 cooling water outlet: sending the cooling water that has absorbed the condensation heat and absorption heat of the unit back to the cooling tower or other heat dissipation equipment (higher temperature); 1 chilled water / cold water outlet: delivering the low-temperature cold water generated by the unit to the air-conditioning terminal or process equipment (lower temperature); 1 chilled water / cold water inlet: receiving return water (higher temperature) from the air-conditioning terminal (such as fan coil units, air handling units, etc.) or process equipment that needs to be cooled; 1 steam inlet: receiving steam that drives the unit (as a heat source); 1 condensate outlet / drain: discharging the condensate generated after the steam condenses and releases heat in the high-pressure generator out of the unit, usually returning it to the boiler room or condensate recovery system; cooling water and chilled water each have an inlet and an outlet, forming an independent circulation loop.

[0031] During the heating season, low-pressure steam is directly connected to the coal mine steam pipeline network 9 to provide heat source for the coal mine office and factory building heating systems and shaft antifreeze heating devices, meeting the coal mine's winter heat load demand.

[0032] During the non-heating season, low-pressure steam is used as a driving energy source to power a steam-based absorption refrigeration unit 10, such as a steam-based lithium bromide chiller, to produce 7°C air-conditioning chilled water. A portion of this 7°C air-conditioning chilled water is delivered via a cooling pipeline to the ground-level building's air conditioning terminal heat exchanger 11, meeting the building's cooling load. A portion is delivered to the wellhead's surface cooling heat exchanger 12, cooling the mine's incoming air and, consequently, the underground working environment. The loads of both systems can be adjusted as needed. After the return water temperature rises to 12°C, it returns to the absorption refrigeration unit 10 for further cooling, completing the cycle.

[0033] The high-temperature condensed water discharged from the absorption refrigeration unit 10 is recovered to the hot water tank 13 through a pipeline and used for domestic hot water scenes such as staff bathrooms and laundry rooms, thereby improving the heat utilization efficiency of the system.

[0034] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A coal mine cooling, heating and power district energy system based on an ultra-low concentration gas-fired biomass boiler is characterized by: It includes an ultra-low concentration gas treatment module, a biomass boiler module connected to the ultra-low concentration gas treatment module, a steam turbine power generation module driven by steam generated by the biomass boiler module, and an absorption refrigeration module that receives low-pressure steam discharged from the steam turbine power generation module; The ultra-low concentration gas processing module is used to mix the extracted gas with a concentration lower than 8% with the exhaust gas with a concentration lower than 0.75%.

2. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 1 is characterized by: The ultra-low concentration gas processing module includes a mixing device (3); the biomass boiler module includes a biomass boiler (5) connected to the mixing device (3) via an induced draft duct.

3. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: The biomass boiler (5) uses biomass fuel, and the biomass fuel uses bulk materials or biomass pellets.

4. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: The biomass boiler (5) is provided with a flue gas outlet (6), and is equipped with a dust removal device, a nitrogen oxide removal device, and a flue gas waste heat recovery heat exchanger; the flue gas at the flue gas outlet (6) passes through the dust removal device, the nitrogen oxide removal device, and the flue gas waste heat recovery heat exchanger and is then discharged.

5. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: The ultra-low concentration gas processing module further comprises a gas extraction pipeline and a gas exhaust pipeline fixedly connected to the mixing device (3); the gas extraction pipeline is provided with a gas extraction pipeline flow regulating valve (1); and the gas exhaust pipeline is provided with a gas exhaust pipeline flow regulating valve (2).

6. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: The steam turbine power generation module comprises a steam turbine (7) and a generator (8) drivingly connected to the steam turbine (7); the air inlet of the steam turbine (7) is fixedly connected to the exhaust port of the biomass boiler (5) for transmitting high-temperature and high-pressure steam.

7. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: The absorption refrigeration module comprises an absorption refrigeration unit (10); the exhaust port of the steam turbine (7) is respectively connected to the coal mine steam pipeline (9) and the absorption refrigeration unit (10); the cold water drain port of the absorption refrigeration unit (10) is respectively connected to the building air conditioning terminal heat exchanger (11) and the air inlet wellhead surface cooling heat exchanger (12); the drain ports of the building air conditioning terminal heat exchanger (11) and the air inlet wellhead surface cooling heat exchanger (12) are respectively connected to the water inlet of the absorption refrigeration unit (10); and the high-temperature drain port of the absorption refrigeration unit (10) is connected to the hot water tank (13).

8. The coal mine cooling, heating and power district energy system based on ultra-low concentration gas mixed with biomass boiler according to claim 2 is characterized by: A gas concentration sensor (4) is provided at the outlet of the mixing device (3) or on the induced air duct, and the concentration of the mixed gas ranges from 1% to 2%.

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