Efficient coal mine gas treatment device and method

Abstract

The invention relates to an efficient coal mine gas treatment device and method.The treatment device comprises a cooling section and a dewatering section which are sequentially connected through a gas inlet pipeline, the cooling section is provided with a heat exchanger, the dewatering section is provided with a main steam-water separator, the gas inlet end of the heat exchanger is provided with a bypass gas path, and the dewatering section is provided with an auxiliary steam-water separator; the bypass gas path is connected with the gas inlet end of the auxiliary steam-water separator, and the gas outlet end of the auxiliary steam-water separator is connected to the gas inlet end of the main steam-water separator. By reasonably arranging the auxiliary steam-water separator, the problems of poor gas dehydration effect and low power generation efficiency caused by water content and pressure fluctuation of a gas source can be solved.

Description

Technical Field

[0001] This invention belongs to the field of gas power generation technology, specifically relating to a high-efficiency coal mine gas treatment device and method. Background Technology

[0002] Low-concentration methane typically refers to methane extracted from mines with methane concentrations between 6% and 30%. Due to its low concentration and high flammability and explosiveness, this type of methane has traditionally been difficult to utilize directly. However, by employing multi-stage flame arresters and water mist delivery systems, low-concentration methane is now widely used for power generation.

[0003] The temperature and moisture content of gas have a significant impact on the efficiency of gas power generation, especially the moisture content. On one hand, the presence of moisture causes unstable fluctuations in the concentration of the gas-air mixture entering the engine cylinder, leading to inconsistent fuel supply and incomplete, unstable combustion, severely reducing the effective power generation per unit volume of gas. On the other hand, the phase change (vaporization) of moisture in the high-temperature cylinder requires the absorption of a large amount of latent heat of vaporization. This heat energy, which should have been used to drive power generation, is wasted, significantly reducing the actual power generation per unit volume of gas. Furthermore, the continuous flow of water-containing gas through the generator set exacerbates corrosion, wear, and scaling of critical components, leading to increased maintenance frequency and costs, shortening the equipment's trouble-free continuous operation time, and ultimately adversely affecting the equipment's lifespan.

[0004] The currently used circulating water cooling system can effectively control the temperature of the methane gas. Furthermore, the moisture content of the methane gas can be reduced by a steam-water separator. The moisture in the methane gas source originates from coal seam water, drilling water, the humid underground environment, and moisture introduced during water ring pump extraction. This results in fluctuations in water content, specifically manifested in significant variations in the daily dehydration capacity of the steam-water separator. Simultaneously, the methane gas source also experiences pressure fluctuations. All these fluctuations significantly impact the dehydration rate of the steam-water separator, leading to poor methane gas dehydration and further affecting the efficiency of methane power generation. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, this invention provides a high-efficiency coal mine gas treatment device, the specific solution of which is as follows:

[0006] A high-efficiency coal mine gas treatment device includes a cooling section and a dehydration section connected in sequence through an air inlet pipeline. The cooling section is equipped with a heat exchanger, and the dehydration section is equipped with a main steam-water separator. The air inlet end of the heat exchanger is provided with a bypass air passage, and the dehydration section is equipped with a secondary steam-water separator. The bypass air passage is connected to the air inlet end of the secondary steam-water separator, and the air outlet end of the secondary steam-water separator is connected to the air inlet end of the main steam-water separator.

[0007] Furthermore, both the main steam-water separator and the auxiliary steam-water separator are cyclone type steam-water separators.

[0008] The principle of a cyclone gas-liquid separator is that after the gas source enters the separator, it rotates at high speed in a spiral direction. Water droplets in the gas are "thrown" onto the separator wall by centrifugal force and discharged by gravity, thus achieving gas-liquid separation. Its dehydration efficiency is affected by the gas flow rate and water content. When the gas source pressure is low and the gas flow rate is small, the centrifugal force on the water droplets will decrease, and the dehydration efficiency will decrease. If the water content of the gas source is too high, exceeding the load, the water film on the separator wall will be thick and easily carried away by the airflow, which will also lead to a decrease in dehydration efficiency.

[0009] By installing a secondary steam-water separator, a portion of the gas source can be introduced into the secondary steam-water separator via a bypass gas path for dehydration. When the moisture content of the gas source is too high, this solution can reduce the workload of the main steam-water separator.

[0010] In addition, in the existing technology, the gas source is cooled by a heat exchanger and then enters the steam-water separator for dehydration. The heat exchanger will cause a pressure loss of 0.1-0.2MPa. The bypass gas path goes directly into the auxiliary steam-water separator without going through the heat exchanger, which can avoid this pressure loss.

[0011] Furthermore, a flow distribution valve is provided at the connection between the bypass gas path and the heat exchanger inlet. The flow distribution valve is used to regulate the gas flow rate of the bypass gas path.

[0012] An improved design involves connecting the auxiliary steam-water separator and the main steam-water separator to separate water tanks, each equipped with a level gauge. The water tank with the level gauge can be used to detect the amount of water removed by the steam-water separator. When the gas source pressure fluctuation is small, a larger amount of water removed by the steam-water separator indicates a higher water content in the gas source itself.

[0013] Another improved design incorporates a pressure detection point at the heat exchanger inlet, located upstream of the flow distribution valve. This pressure detection point is used to monitor the gas source pressure and can be achieved using a conventional pressure gauge.

[0014] Based on the first improved scheme, a method for efficient treatment of coal mine gas is also provided, which increases the bypass gas flow rate when the dehydration capacity of the auxiliary steam-water separator increases.

[0015] Since the dehydration capacity of the steam-water separator reflects the moisture content of the gas source, the separation efficiency of the main steam-water separator will decrease when the moisture content of the gas source increases. Therefore, increasing the bypass gas flow rate can maintain the stable separation efficiency of the main steam-water separator.

[0016] Based on the second improved scheme, another efficient method for treating coal mine gas is also provided: when the pressure detected at the pressure detection point drops, the flow rate of the bypass gas path is increased.

[0017] When the gas source pressure drops, the separation efficiency of the steam-water separator will also decrease. Since there is a pressure drop when the gas passes through the heat exchanger, a portion of the gas source can directly enter the auxiliary steam-water separator through the bypass gas path for dehydration, which can reduce the impact of pressure loss.

[0018] Furthermore, when using the above two methods, the cooling water flow rate of the heat exchanger should be increased when the bypass airflow is increased.

[0019] Because the gas source via the bypass gas path does not pass through a heat exchanger for cooling, the gas temperature can exceed the control temperature. This solution increases the cooling water flow rate of the heat exchanger, which can reduce the gas temperature of the main gas source to below the control range. Then, it is mixed with the uncooled gas from the bypass gas path. Finally, the temperature of the mixed gas can be kept within the control range, thus solving the above problem.

[0020] This invention solves the problem of poor gas dehydration and low power generation efficiency caused by fluctuations in gas source moisture content and pressure by rationally setting up a secondary steam-water separator. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an existing coal mine gas treatment device.

[0022] Figure 2 This is a schematic diagram of the coal mine gas high-efficiency treatment device of the present invention. Detailed Implementation

[0023] Prior to this invention, the method used was as follows: Figure 1 The coal mine gas treatment device shown includes a heat exchanger and a steam-water separator. The heat exchanger is a tubular heat exchanger, utilizing two existing open cooling towers as a cold source to stably reduce the gas temperature to 30-40℃. After cooling, the gas then enters the steam-water separator for dehydration. The following describes the process... Figure 1 The system shown contains a portion of its operational data.

[0024]

[0025] It can be seen that the power generation efficiency is between 1.8 and 2.0 kWh / Nm³.

[0026] like Figure 2The diagram shows the efficient coal mine gas treatment device of the present invention. Based on the original system, a bypass gas path 4 is added to the inlet end of the heat exchanger 3. A flow distribution valve 5 is installed at the connection of the bypass gas path 4. A secondary steam-water separator 2 is installed in the bypass gas path, and the secondary steam-water separator 2 is then connected to the inlet end of the main steam-water separator 1. The nominal diameter of the secondary steam-water separator is smaller than that of the main steam-water separator. The drain valve outlets of both the main steam-water separator 1 and the secondary steam-water separator 2 are connected to independent water tanks equipped with level gauges, allowing for the measurement of the amount of water removed per unit time. During operation, a pressure gauge 6 is used to monitor the gas source pressure, which fluctuates between 0.5 and 0.8 MPa. The water tank is used to measure the amount of water removed by the steam-water separators, with the daily water removal capacity of the secondary steam-water separator fluctuating between 0.9 and 2.0 t.

[0027] When the gas source pressure is below 0.6 MPa, the bypass gas flow rate ratio should be adjusted to 0.2-0.3; when the gas source pressure is above 0.6 MPa, the bypass gas flow rate ratio should be adjusted to 0-0.2.

[0028] When the daily dehydration capacity of the auxiliary steam-water separator is higher than 1 t, the bypass air flow rate ratio should be adjusted to 0.2-0.3; when the daily dehydration capacity of the auxiliary steam-water separator is lower than 1 t, the bypass air flow rate ratio should be adjusted to 0-0.2.

[0029] During operation, adjustments based on the daily dehydration rate of the auxiliary steam-water separator take precedence over the gas source pressure. Generally, the bypass gas flow rate is initially adjusted based on the previous day's daily dehydration rate of the auxiliary steam-water separator, and then adaptive adjustments are made according to the gas source pressure.

[0030] For example, if the daily dehydration capacity of the auxiliary steam-water separator is 1.5t, the bypass airflow ratio should be adjusted to 0.25. If the gas source pressure drops below 0.6MPa, the bypass airflow ratio should be further adjusted to 0.28. If the gas source pressure is not lower than 0.6MPa, the bypass airflow ratio should be kept constant at 0.25.

[0031] For example, if the daily dehydration capacity of the auxiliary steam-water separator is 0.8t, then the bypass airflow ratio should be adjusted to 0.18. If the gas source pressure is lower than 0.6 MPa, the bypass airflow should be increased to 0.20. If the gas source pressure is not lower than 0.6 MPa, the bypass airflow should remain unchanged at 0.18.

[0032] The following is adopted Figure 2 The system shown contains a portion of its operational data.

[0033]

[0034] As can be seen, after the improvement, the power generation efficiency increased to 2.4-2.6 kWh / Nm³.

Claims

1. A high-efficiency coal mine gas treatment device, comprising a cooling section and a dehydration section connected sequentially via an inlet pipeline, wherein the cooling section is equipped with a heat exchanger and the dehydration section is equipped with a main steam-water separator, characterized in that, The heat exchanger has a bypass air passage at the air inlet end and a secondary steam-water separator in the dehydration section. The bypass air passage is connected to the air inlet end of the secondary steam-water separator, and the air outlet end of the secondary steam-water separator is connected to the air inlet end of the main steam-water separator.

2. The high-efficiency coal mine gas treatment device according to claim 1, characterized in that, Both the main steam-water separator and the auxiliary steam-water separator are cyclone type steam-water separators.

3. The high-efficiency coal mine gas treatment device according to claim 1, characterized in that, A flow distribution valve is provided at the connection between the bypass air passage and the air inlet of the heat exchanger.

4. The high-efficiency coal mine gas treatment device according to claim 3, characterized in that, The auxiliary steam-water separator and the main steam-water separator are each connected to a separate water tank, and the water tank is equipped with a level gauge.

5. The high-efficiency coal mine gas treatment device according to claim 3, characterized in that, A pressure detection point is provided at the inlet end of the heat exchanger, and the pressure detection point is located upstream of the flow distribution valve.

6. A method for efficient treatment of coal mine methane, characterized in that, The coal mine gas high-efficiency treatment device as described in claim 4 is used, and when the dehydration of the auxiliary steam-water separator increases, the bypass gas flow rate is increased.

7. A method for efficient treatment of coal mine methane, characterized in that, When the pressure detected at the pressure detection point drops using the high-efficiency coal mine gas treatment device as described in claim 5, the bypass gas flow rate is increased.

8. The method for efficient treatment of coal mine gas according to claim 6 or 7, characterized in that, When the bypass airflow is increased, the cooling water flow rate of the heat exchanger is also increased.

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