CN-117606014-B - Method for generating power by combining in-situ combustion of hot flue gas modified ultrathin coal seam with steam

CN117606014BCN 117606014 BCN117606014 BCN 117606014BCN-117606014-B

Abstract

The disclosure relates to the field of development and utilization of coal seam resources, in particular to a method for generating electricity by in-situ combustion and water vapor of a hot flue gas modified ultrathin coal seam. According to the method, the hot flue gas is utilized to thermally modify the ultrathin coal seam, so that the permeability of the coal seam is increased, and meanwhile, the flue gas component is utilized to displace the coal seam gas, so that the improvement of the coal seam gas migration environment is realized, the mobility of the air flow in the coal seam is ensured, and the air condition is provided for the in-situ combustion of the subsequent coal seam. The water injection heat regeneration subsystem capable of matching with the in-situ combustion of the ultrathin coal seam is formed by drilling holes along the seam and nesting refractory water pipes, and air is injected into the ultrathin coal seam to induce the coal seam to generate in-situ spontaneous combustion, so that a large amount of heat energy is generated and water vapor is heated, and the in-situ combustion heat energy of the coal seam is extracted. Aiming at an extremely thin coal seam, the coal resource is developed and utilized in a mode of in-situ combustion of the coal seam and water vapor power generation, and the method has important significance for high-efficiency utilization of the coal resource and multistage energy of China.

Inventors

LIN BAIQUAN
ZHA WEI
LIU TONG
MA SHUNQING
LIN MINGHUA

Assignees

中国矿业大学

Dates

Publication Date: 20260508
Application Date: 20231115

Claims (4)

1. The method for generating electricity by combining in-situ combustion of hot flue gas modified ultrathin coal seam with water vapor is characterized by comprising the following steps of: (1) The method comprises the steps of dividing an extremely thin coal layer into a combustion area and a non-combustion area positioned around the combustion area, constructing a extraction well and at least one gas injection well from the ground to the combustion area, wherein the area between the extraction well and the gas injection well can cover the combustion area; (2) Injecting hot flue gas into the combustion zone from the gas injection well through gas injection equipment to expand and increase the coal seam cracks of the combustion zone of the ultrathin coal bed, increasing the coal seam air permeability of the combustion zone, simultaneously extracting the coal seam gas produced by the displacement of the hot flue gas by using extraction equipment from an extraction well, and conveying the obtained extracted gas to a coal seam gas purification device for purification and utilization; (3) Constructing a first vertical shaft and a second vertical shaft respectively from a non-combustion area positioned on two opposite sides of a combustion area, constructing two drilling operation surfaces along the direction of an extremely thin coal seam respectively adjacent to the first vertical shaft and the second vertical shaft, constructing a plurality of bedding drilling holes along the direction of the extremely thin coal seam by the drilling operation surfaces, wherein the bedding drilling holes penetrate through the combustion area; (4) A fire-resistant wall is built at the juncture of the combustion area and the non-combustion area, wherein the fire-resistant wall can divide the two drilling operation surfaces into the same combustion area; (5) The method comprises the steps of starting a water inlet valve and a gas outlet valve, starting the water inlet pump to inject a water source into a refractory water pipe from a water inlet main pipe until the water content in all pipelines reaches 80%, stopping water injection, closing the water inlet valve and the gas outlet valve, injecting air from a gas injection well to a combustion zone through gas injection equipment to induce in-situ spontaneous combustion of an extremely thin coal layer, simultaneously pumping tail gas generated by in-situ spontaneous combustion of the extremely thin coal layer by using pumping equipment from the pumping well, conveying the obtained pumping gas to a tail gas treatment device for purification, discharging, heating water in the refractory water pipe at high temperature generated by in-situ spontaneous combustion of the extremely thin coal layer, and producing water vapor, monitoring the water vapor pressure in the gas outlet main pipe in real time through a water vapor pressure meter, opening the gas outlet valve when the water vapor pressure in the gas outlet main pipe reaches the working pressure of a vapor generator, enabling the water vapor to enter the vapor generator for power generation, conveying electric energy generated by the vapor generator to a power user through a power transmission line, and conveying vapor generated after power generation of the vapor generator to a thermal user for recycling residual heat energy in the vapor.
2. The method for generating power by combining in-situ combustion and steam of a hot flue gas modified ultrathin coal seam according to claim 1, wherein the number of gas injection wells and gas injection equipment is two, the two gas injection wells are respectively arranged adjacent to two drilling operation surfaces, and the extraction well is positioned in the middle of the two gas injection wells.
3. The hot flue gas modified ultrathin coal seam in-situ combustion synergistic steam power generation system is characterized by comprising an ultrathin coal seam, a gas injection extraction subsystem, a water injection heat regeneration subsystem, a steam power generation subsystem and a fire wall; the fire-resistant wall is arranged at the junction of the combustion zone and the non-combustion zone; The gas injection extraction subsystem comprises an extraction well, extraction equipment, a coal bed gas purification device, a tail gas treatment device, at least one gas injection well and at least one gas injection equipment; the extraction well and the gas injection well are both extended to the combustion zone from the ground, and the area between the extraction well and the gas injection well can cover the combustion zone, the gas injection device is configured to inject hot flue gas or air into the gas injection well, the extraction device is configured to extract coal bed gas produced by the displacement of the hot flue gas or tail gas produced by spontaneous combustion of the combustion zone under the action of the air from the extraction well, the coal bed gas purification device is communicated with the extraction device, and the tail gas treatment device is communicated with the extraction device; The water injection heat regeneration subsystem comprises a first vertical shaft, a second vertical shaft, two drilling surfaces, a plurality of bedding drilling holes along the direction of the extremely thin coal seam, a water source, a water inlet pump, a water inlet valve, a water inlet main pipe, a fire-resistant water pipe, an air outlet main pipe, a water vapor pressure gauge and an air outlet valve, wherein the first vertical shaft and the second vertical shaft extend from the ground to the non-combustion area positioned at two opposite sides of the combustion area, the two drilling surfaces are respectively arranged close to the first vertical shaft or the second vertical shaft and are configured to construct the bedding drilling holes, the bedding drilling holes penetrate through the combustion area, the fire-resistant water pipe is nested inside the bedding drilling holes, the water inlet main pipe is communicated with the first end of the fire-resistant water pipe through the first vertical shaft, the water inlet main pipe is communicated with the water source, the water inlet pump and the air outlet main pipe are arranged on the water inlet main pipe, the air outlet pump is communicated with the second end of the fire-resistant water pipe through the second vertical shaft, and the air outlet valve is arranged on the main pipe; The steam power generation subsystem comprises a steam generator, a power transmission line, a power user and a heat user, wherein the steam generator is connected with the power user through the power transmission line, and the steam generator is connected with the heat user.
4. The hot flue gas modified ultra-thin coal seam in-situ combustion collaborative steam power generation system according to claim 3, wherein the gas injection extraction subsystem comprises two gas injection wells and two gas injection devices, wherein the two gas injection wells are respectively arranged adjacent to two drilling operation surfaces, and the extraction well is positioned in the middle of the two gas injection wells.

Description

Method for generating power by combining in-situ combustion of hot flue gas modified ultrathin coal seam with steam Technical Field The disclosure relates to the field of development and utilization of coal seam resources, in particular to a method for generating electricity by in-situ combustion and water vapor of a hot flue gas modified ultrathin coal seam. Background Compared with the main coal seam, the low coal seam has the advantages of poor gas content, high exploitation difficulty, high cost and low benefit, and is long-term regarded as marginal resource in the development of coal seam gas. The extremely thin coal seam in the thin coal seam is often not developed and utilized due to factors such as small coal seam thickness, difficult exploitation and the like. However, in recent years, chemical gasification for extremely thin coal seams is performed by extracting combustible gas generated by gasification reaction of coal seams, and chemical gasification is greatly affected by low efficiency of chemical reaction and environmental openness such as coal seam faults. Disclosure of Invention Technical problems: The in-situ combustion collaborative steam power generation method and system suitable for the extremely thin non-acquirable coal seam are provided, and extraction of coal bed gas and efficient extraction of in-situ combustion heat energy of the extremely thin coal seam are synchronously realized. The technical scheme is as follows: In one aspect, a method for generating electricity by in-situ combustion and co-steam generation of a hot flue gas modified ultrathin coal seam is provided, which comprises the following steps: (1) The method comprises the steps of dividing an extremely thin coal layer into a combustion area and a non-combustion area positioned around the combustion area, constructing a extraction well and at least one gas injection well from the ground to the combustion area, wherein the area between the extraction well and the gas injection well can cover the combustion area; (2) Injecting hot flue gas into the combustion zone from the gas injection well through gas injection equipment to expand and increase the coal seam cracks of the combustion zone of the ultrathin coal bed, increasing the coal seam air permeability of the combustion zone, simultaneously extracting the coal seam gas produced by the displacement of the hot flue gas by using extraction equipment from an extraction well, and conveying the obtained extracted gas to a coal seam gas purification device for purification and utilization; (3) Constructing a first vertical shaft and a second vertical shaft respectively from a non-combustion area positioned on two opposite sides of a combustion area, constructing two drilling operation surfaces along the direction of an extremely thin coal seam respectively adjacent to the first vertical shaft and the second vertical shaft, constructing a plurality of bedding drilling holes along the direction of the extremely thin coal seam by the drilling operation surfaces, wherein the bedding drilling holes penetrate through the combustion area; (4) Building a fire-resistant wall at the juncture of the combustion area and the non-combustion area, wherein the fire-resistant wall can divide the two drilling operation surfaces into two areas with the same combustion area so as to protect the two drilling operation surfaces, the first vertical shaft and the second vertical shaft when the combustion area of the subsequent extremely thin coal layer is in-situ spontaneous combustion; (5) The method comprises the steps of starting a water inlet valve and a gas outlet valve, starting the water inlet pump to inject a water source into a refractory water pipe from a water inlet main pipe until the water content in all pipelines reaches 80%, stopping water injection, closing the water inlet valve and the gas outlet valve, injecting air from a gas injection well to a combustion zone through gas injection equipment to induce in-situ spontaneous combustion of an extremely thin coal layer, simultaneously pumping tail gas generated by in-situ spontaneous combustion of the extremely thin coal layer by using pumping equipment from the pumping well, conveying the obtained pumping gas to a tail gas treatment device for purification, discharging, heating water in the refractory water pipe at high temperature generated by in-situ spontaneous combustion of the extremely thin coal layer, and producing water vapor, monitoring the water vapor pressure in the gas outlet main pipe in real time through a water vapor pressure meter, opening the gas outlet valve when the water vapor pressure in the gas outlet main pipe reaches the working pressure of a vapor generator, enabling the water vapor to enter the vapor generator for power generation, conveying electric energy generated by the vapor generator to a power user through a power transmission line, and conveying vapor generated after power generation of the vapor g