Coal mine cold-heat-electricity regional energy system based on biomass boiler mixed with ultra-low concentration gas

Abstract

The utility model relates to the field of coal mine energy resource utilization and energy -conserving and environment -protecting technology discloses a kind of coal mine cold and heat power district energy system based on ultra-low concentration gas mixed burning biomass boiler, including ultra-low concentration gas processing module, the biomass boiler module being communicated with ultra-low concentration gas processing module, steam turbine power generation module being driven by steam generated by biomass boiler module, and absorption refrigeration module working by receiving low-pressure steam discharged by steam turbine power generation module.The utility model solves the problem of low utilization efficiency of ultra-low concentration gas by mixing ultra-low concentration wind exhaust gas and low concentration extraction gas and adding them into boiler together with biomass for mixed burning, and can also provide cold and heat energy for coal mine.

Description

Technical Field

[0001] This utility model relates to the field of coal mine energy resource utilization and energy conservation and environmental protection technology, specifically to a coal mine cold, heat and power regional energy system based on an ultra-low concentration gas co-firing biomass boiler. Background Technology

[0002] The vast majority of my country's coal mines are located in the cold northern regions, resulting in huge demands for heat supply, including 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 for heating in coal mines has been restricted, forcing many mines to adopt gas-fired or electric boilers. However, this has led to a sharp increase in heating costs, making it urgent for coal mines to find new low-carbon, low-cost heating methods. Biomass, as a renewable energy source, is widely available and environmentally friendly. Furthermore, compared to natural gas boilers, biomass boilers have a significant competitive advantage in heating costs. However, there is still considerable room for improvement in the energy efficiency of biomass boilers. In addition, with the continuous development of deep coal mines, the demand for mine cooling is increasing, making the efficient solution to mine cooling problems 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. Classified by methane concentration, based on current technology and market application, high-concentration coalbed methane resources (over 30%) can be directly used for internal combustion engine power generation or concentrated into CNG / LNG. The state has already banned the direct emission of this type of gas, and the market utilization rate is close to 100%. For low-concentration methane (8%–30%), combustion or direct internal combustion engine power generation technologies are mature, and the market utilization rate is around 70%. With the latest national emission ban standards for this concentration range, its market utilization rate is expected to quickly reach 100%. Meanwhile, extracted methane (concentration below 8%) and ventilation methane (concentration below 0.75%) account for 80% of total coal mine gas emissions. Currently, almost all of these are directly emitted into the air, resulting in extremely low market utilization. This not only wastes resources but also has a significant impact on the atmospheric environment, making it a key area for future coal mine gas utilization.

[0004] While there are currently some schemes that combine biomass with low-concentration methane combustion, such as the Chinese utility model patent CN104990092 A entitled "Method and System for Combustion of Ultra-Low Concentration Methane" and the Chinese utility model patent CN116241878 A entitled "A Self-Excited Oscillation Combustion of Low Concentration Methane Coupled with Biomass," these low-concentration methane combustion schemes all use biomass as fuel to ignite ultra-low concentration methane, producing high-temperature flue gas. Their combustion is not significantly different from other methane combustion methods, and there are no new directions for utilizing their combustion products. Therefore, my country's coal mines urgently need a regional energy system that can fully utilize ultra-low concentration methane resources in coal mines and achieve green, low-carbon, and low-cost combined cooling, heating, and power (CCHP) systems. Utility Model Content

[0005] The purpose of this utility model is to overcome the shortcomings of the existing technology and provide a coal mine cold, heat and power regional energy system based on an ultra-low concentration gas co-firing biomass boiler. By mixing ultra-low concentration exhaust gas with low concentration extracted gas and adding it to the boiler along with biomass for co-firing, the problem of low utilization efficiency of ultra-low concentration gas is solved, and at the same time, it can provide cold and heat energy for coal mines.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a coal mine cooling, heating and power regional energy system based on an ultra-low concentration gas co-firing 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 connected to the high temperature and high pressure steam exhaust port of the biomass boiler module, and an absorption refrigeration module connected to the low pressure steam exhaust port of the steam turbine power generation module.

[0007] The ultra-low concentration gas treatment module includes a mixing device, a gas extraction pipeline for feeding extracted gas with a concentration of less than 8% into the mixing device, and a gas exhaust pipeline for feeding exhaust gas with a concentration of less than 0.75% into the mixing device.

[0008] Furthermore, the biomass boiler module includes a biomass boiler; the biomass boiler and the mixing device are connected via an induced draft duct.

[0009] Furthermore, biomass boilers use biomass fuel, which can be either bulk or in pellet form.

[0010] Furthermore, the biomass boiler is equipped with a flue gas outlet, which is equipped with a dust removal device, a nitrogen oxide removal device, and a flue gas waste heat recovery heat exchanger for treating high-temperature flue gas.

[0011] Furthermore, the gas extraction pipeline is equipped with a gas extraction pipeline flow regulating valve; the ventilation gas pipeline is equipped with a ventilation gas pipeline flow regulating valve.

[0012] Furthermore, the steam turbine power generation module includes a steam turbine and a generator that is driven and connected to the steam turbine; the steam turbine's air inlet is fixedly connected to the biomass boiler's exhaust outlet.

[0013] Furthermore, the absorption refrigeration module includes an absorption chiller unit; the turbine exhaust port is connected to the coal mine steam pipeline and the absorption chiller unit respectively; the cold water drain outlet of the absorption chiller unit is connected to the building air conditioning terminal heat exchanger and the air inlet well surface cooling heat exchanger respectively; the drain outlets of the building air conditioning terminal heat exchanger and the air inlet well surface cooling heat exchanger are connected to the water inlet of the absorption chiller unit respectively; and the high-temperature drain outlet of the absorption chiller unit is connected to the hot water tank.

[0014] Furthermore, the turbine exhaust port is connected to the first main pipeline, which in turn connects to two first branch pipelines. These two branch pipelines are respectively connected to the coal mine steam pipeline and the absorption chiller unit. Each of the two branch pipelines is equipped with a first valve for controlling its opening and closing. The exhaust port of the absorption chiller unit is connected to a second main pipeline, which in turn connects to two second branch pipelines. These two branch pipelines are respectively connected to the building air conditioning terminal heat exchanger and the air inlet well surface cooling heat exchanger. Each of the two branch pipelines is equipped with a second valve for controlling its opening and closing.

[0015] Furthermore, the turbine exhaust port is connected to the first main pipeline, which in turn connects to two first branch pipelines. These two branch pipelines are respectively connected to the coal mine steam pipeline and the absorption chiller unit. Each of the two branch pipelines is equipped with a first valve for controlling its opening and closing. The exhaust port of the absorption chiller unit is connected to a second main pipeline, which in turn connects to two second branch pipelines. These two branch pipelines are respectively connected to the building air conditioning terminal heat exchanger and the air inlet well surface cooling heat exchanger. Each of the two branch pipelines is equipped with a second valve for controlling its opening and closing.

[0016] Furthermore, a gas concentration sensor is installed at the outlet of the mixing unit or on the exhaust duct.

[0017] The beneficial effects of this utility model are: (1) By mixing ultra-low concentration exhaust gas with low concentration extraction gas and adding it to the boiler along with biomass for co-firing, the problem of low utilization efficiency of ultra-low concentration gas is solved, and at the same time, it can provide cold and hot energy for coal mines; reducing resource waste and environmental impact, and meeting the requirements of the dual carbon policy.

[0018] (2) Improve the thermal efficiency of biomass boilers: The co-firing of ultra-low concentration gas provides additional heat to biomass boilers, improves combustion conditions, and increases the thermal efficiency of biomass boilers, making energy utilization more efficient.

[0019] (3) Meeting the comprehensive energy needs of coal mines for green, low-carbon, and low-cost use: By utilizing biomass, a renewable energy source, and combining it with the co-firing of ultra-low concentration methane, the energy procurement costs of coal mines are reduced. The dust removal and denitrification devices equipped in biomass boilers ensure that combustion emissions meet environmental protection standards, reduce pollutant emissions, and have good environmental benefits.

[0020] (4) Achieving efficient cascade utilization of energy: Through combined cooling, heating and power (CCHP), waste heat recovery from boiler flue gas, and connection of high-temperature condensate to domestic hot water tanks, efficient cascade utilization of energy is achieved. Heating and cooling needs are met in the heating season and summer, respectively, ensuring the annual absorption capacity of ultra-low concentration methane from coal mines and the stable annual load operation of biomass boilers, thereby improving the efficiency, economy and reliability of the energy system. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the process of this utility model.

[0022] In the diagram: 1. Gas extraction pipeline flow regulating valve; 2. Gas exhaust pipeline flow regulating valve; 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 chiller unit; 11. Building air conditioning terminal heat exchanger; 12. Air inlet wellhead surface heat exchanger; 13. Hot water tank. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] The directional terms mentioned in this utility model, such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", "top" and "bottom", are only for reference to the orientation of the accompanying drawings. The directional terms used are for the purpose of explaining and understanding this utility model, and are not intended to limit this utility model.

[0025] Example:

[0026] like Figure 1 As shown, a coal mine cooling, heating and power regional energy system based on an ultra-low concentration gas co-firing biomass boiler 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 the steam generated by the biomass boiler module, and an absorption refrigeration module that receives the low-pressure steam discharged from the steam turbine power generation module.

[0027] The ultra-low concentration gas treatment module is used to mix extracted gas with a concentration of less than 8% with ventilation gas with a concentration of less than 0.75%.

[0028] The ultra-low concentration gas treatment 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 gas is fed into the biomass boiler 5 and co-fired with biomass fuel via the induced draft fan.

[0029] The biomass boiler 5 uses biomass fuel, which can be either bulk material or biomass pellets. Bulk material refers to uncompressed raw biomass materials that are loose in shape, including agricultural and forestry waste such as sawdust, straw fragments, branches, and rice husks. Pellets refer to cylindrical solid particles (with a diameter of 6-10 mm and a length of 10-30 mm) made from bulk material after drying, crushing, and high-pressure compression.

[0030] The biomass boiler 5 is equipped with a flue gas outlet 6 and a dust removal device, a nitrogen oxide removal device, and a flue gas waste heat recovery heat exchanger. The flue gas from the outlet 6 is discharged after passing through the dust removal device, nitrogen oxide removal device, and flue gas waste heat recovery heat exchanger. The waste heat recovery heat exchanger is used to exchange heat between the dust-removed high-temperature flue gas and the boiler feed water, thereby reducing the exhaust gas temperature and increasing the feed water temperature. Specifically, the waste heat recovery heat exchanger performs counter-current heat exchange between the dust-removed high-temperature flue gas and the boiler feed water (temperature around 25℃), reducing the exhaust gas temperature to below 110℃ while simultaneously increasing the feed water temperature to around 90℃, significantly improving the boiler's thermal efficiency.

[0031] The ultra-low concentration gas treatment module also includes a gas extraction pipeline and a gas exhaust pipeline that are fixedly connected to the mixing device 3; the gas extraction pipeline is equipped with a gas extraction pipeline flow regulating valve 1; the gas exhaust pipeline is equipped with a gas exhaust pipeline flow regulating valve 2.

[0032] The steam turbine generator module includes a steam turbine 7 and a generator 8 driven by the steam turbine 7. The steam turbine generator module can be a back-pressure or extraction steam turbine generator set. The air inlet of the steam turbine 7 is fixedly connected to the exhaust port of the biomass boiler 5 to transmit high-temperature and high-pressure steam. Taking the back-pressure generator set as an example, the high-pressure steam (pressure 2.5MPa) generated by the boiler drives the steam turbine to do work, which in turn drives the generator 8 to generate electricity. The exhaust steam (pressure 0.15MPa) of the back-pressure unit is distributed according to seasonal demand.

[0033] 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 maker; 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 shaft antifreeze heat load; the exhaust port of the steam turbine (7) is generally connected to the first main pipeline, and the first main pipeline is connected to two first branch pipelines at the same time. The two first branch pipelines are connected to the coal mine steam pipeline (9) and the absorption refrigeration unit (10) respectively; each of the two first branch pipelines is equipped with a first valve for controlling opening and closing.

[0034] The chilled water drain outlet of the absorption chiller unit 10 is connected to the building air conditioning terminal heat exchanger 11 and the air inlet well surface cooling heat exchanger 12, respectively, to achieve cooling of the entire air volume of the building air conditioning and the mine. Generally, the exhaust port of the steam turbine 7 is connected to a main pipe, which is connected to two branch pipes. These two branch pipes are connected to the building air conditioning terminal heat exchanger 11 and the air inlet well surface cooling heat exchanger 12, respectively. Both branch pipes are equipped with valves to control their opening and closing. The drain outlets of the building air conditioning terminal heat exchanger 11 and the air inlet well surface cooling heat exchanger 12 are connected to the water inlet of the absorption chiller unit 10, which is used to return the heated water to the absorption chiller unit 10. The high-temperature drain outlet of the absorption chiller unit 10 is connected to the hot water tank 13.

[0035] A typical steam-type lithium bromide chiller unit has six main inlets and outlets: one cooling water inlet (receiving cooling water from a cooling tower or other cooling water source at a higher temperature); one cooling water outlet (returning cooling water that has absorbed the unit's condensation heat and absorbed heat to the cooling tower or other heat dissipation equipment at an even higher temperature); one chilled water / cooled water outlet (transporting the low-temperature chilled water generated by the unit to air conditioning terminals or process equipment at a lower temperature); one chilled water / cooled water inlet (receiving return water from air conditioning terminals (such as fan coil units, air handling units, etc.) or process equipment that needs to be cooled at a higher temperature); one steam inlet (receiving steam to drive the unit's operation as a heat source); and one condensate outlet / drainage outlet (discharging condensate from the high-pressure generator after the steam condenses and releases heat, usually returning it to the boiler room or condensate recovery system); and one inlet and one outlet for each of the cooling water and chilled water, forming independent circulation loops.

[0036] During the heating season, low-pressure steam is directly connected to the coal mine steam pipeline network 9 to provide a heat source for the heating systems of coal mine offices and factory buildings, as well as the anti-freezing heating devices for shafts, thus meeting the winter heat load requirements of the coal mine.

[0037] During the non-heating season, low-pressure steam is used as the driving energy source to power the steam-type absorption chiller unit 10, such as a steam-type lithium bromide chiller unit, to produce 7°C air conditioning chilled water. Part of the 7°C air conditioning chilled water is transported through cooling pipelines to the ground-based building air conditioning terminal heat exchanger 11 to meet the building's cooling load; another part is transported to the air intake surface heat exchanger 12 to cool the mine's intake air, thereby reducing the temperature of the underground working environment. The loads of both can be adjusted as needed. After the return water temperature rises to 12°C, it returns to the absorption chiller unit 10 for further cooling, completing the cycle.

[0038] The high-temperature condensate discharged from the absorption chiller unit 10 is recycled to the hot water tank 13 through pipelines for use in domestic hot water scenarios such as staff bathrooms and laundry rooms, thereby improving the system's heat utilization efficiency.

[0039] The above description is only used to illustrate the technical solution of this utility model and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-co-fired biomass boiler, characterized in that: 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 connected to the high-temperature and high-pressure steam exhaust port of the biomass boiler module, and an absorption refrigeration module connected to the low-pressure steam exhaust port of the steam turbine power generation module. The ultra-low concentration gas treatment module includes a mixing device (3), a gas extraction pipeline for sending extracted gas with a concentration of less than 8% into the mixing device (3), and a gas exhaust pipeline for sending exhaust gas with a concentration of less than 0.75% into the mixing device (3).

2. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-co-fired biomass boiler according to claim 1, characterized in that: The biomass boiler module includes a biomass boiler (5); the biomass boiler (5) is connected to the mixing device (3) via an induced draft pipe.

3. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-co-fired biomass boiler according to claim 2, characterized in that: The biomass boiler (5) uses biomass fuel, which can be either bulk or biomass pellets.

4. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-coated biomass boiler according to claim 2, characterized in that: The biomass boiler (5) is provided with a flue gas outlet (6), and a dust removal device, a nitrogen oxide removal device and a flue gas waste heat recovery heat exchanger are provided at the flue gas outlet (6) for treating high-temperature flue gas.

5. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-coated biomass boiler according to claim 1, characterized in that: The gas extraction pipeline is equipped with a gas extraction pipeline flow regulating valve (1); the ventilation gas pipeline is equipped with a ventilation gas pipeline flow regulating valve (2).

6. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-blended biomass boiler according to claim 2, characterized in that: The steam turbine power generation module includes a steam turbine (7) and a generator (8) that is driven by the steam turbine (7); the air inlet of the steam turbine (7) is fixedly connected to the exhaust port of the biomass boiler (5).

7. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-co-fired biomass boiler according to claim 1, characterized in that: The absorption refrigeration module includes an absorption refrigeration unit (10); 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 cold water drain outlet of the absorption refrigeration unit (10) is connected to the building air conditioning terminal heat exchanger (11) and the air inlet well surface cooling heat exchanger (12) respectively; the drain outlets of the building air conditioning terminal heat exchanger (11) and the air inlet well surface cooling heat exchanger (12) are connected to the water inlet of the absorption refrigeration unit (10) respectively; the high temperature drain outlet of the absorption refrigeration unit (10) is connected to the hot water tank (13).

8. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-coated biomass boiler according to claim 7, characterized in that: The exhaust port of the steam turbine (7) is connected to the first main pipeline, which is connected to two first branch pipelines. The two first branch pipelines are connected to the coal mine steam pipeline (9) and the absorption chiller unit (10) respectively. Each of the two first branch pipelines is equipped with a first valve for controlling opening and closing. The exhaust port of the absorption chiller unit (10) is connected to a second main pipeline, which is connected to two second branch pipelines. The two second branch pipelines are connected to the building air conditioning terminal heat exchanger (11) and the air inlet well surface heat exchanger (12) respectively. Each of the two second branch pipelines is equipped with a second valve for controlling opening and closing.

9. The coal mine cooling, heating, and power regional energy system based on an ultra-low concentration gas-co-fired biomass boiler according to claim 1, characterized in that: A gas concentration sensor (4) is installed at the outlet of the mixing device (3) or on the exhaust pipe, and the gas concentration after mixing is in the range of 1% to 2%.

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