CN106545876A - A method for heating wellbore with flue gas after gas thermal storage and oxidation - Google Patents

Abstract

The invention relates to a method for heating a shaft by using flue gas after heat storage and oxidation of gas, which comprises the steps of mixing extracted gas with air, sending the mixture to a gas heat storage and oxidation device for oxidation reaction to generate high-temperature flue gas; the generated heat keeps the heat balance of the oxidation device, one part of the flue gas enters the gas/gas heat exchanger to heat the shaft, the other part of the flue gas is respectively sent to the gas/water heat exchanger or the water boiler to generate hot water, and the high-temperature flue gas after heat exchange of the heat exchanger flows back to be mixed with the extracted gas in the blender for the second time; the method provided by the invention can be used for remarkably improving the heat energy utilization efficiency of the system and realizing reasonable distribution of heat energy utilization after gas oxidation.

Description

A method for heating wellbore with flue gas after gas thermal storage and oxidation

technical field

The invention belongs to the field of energy recycling and relates to a method for heating a shaft with flue gas after gas heat storage and oxidation.

Background technique

At present, the main use of low-concentration gas in coal mines is gas power generation, but when the gas concentration fluctuates greatly or the concentration is lower than 8%, the method of gas thermal storage and oxidation is mainly used for destruction and thermal energy utilization. At present, many coal mining enterprises have carried out Industrial test application of gas thermal storage oxidation technology. Gas heat storage oxidation technology is mainly used in coal mines for steam power generation after oxidation, building heating, drying coal slime and bathing. There are also application cases of using the gas thermal storage and oxidation method to heat the wellbore, but there is no method or system to solve the hidden dangers of system operation and ensure the heating effect of the wellbore.

At present, most coal mines use coal-fired hot air stoves or coal-fired boilers to provide heat medium for shaft heating during the heating season. If a coal-fired hot blast stove is used, the coal-fired hot blast stove is used to generate high-temperature air, which is sent to the wellhead and mixed with cold air to 2°C, and then sent underground to heat the wellbore. If a coal-fired boiler is used, steam or hot water will be generated by the boiler and sent to the wellhead heating room to exchange heat with the air, heat the air to a temperature above 40°C, mix it with fresh air to 2°C, and then send it underground .

At present, most coal mines use coal-fired hot air stoves or coal-fired boilers to provide heat medium for shaft heating, and the evaporation capacity of the coal-fired furnaces used is generally 10 tons/h or less, with low energy utilization efficiency and serious pollution. As the situation continues to aggravate, the state's efforts to control the atmospheric environment are increasing, and coal-fired boilers used in coal mines for various heating purposes will be gradually banned.

The invention creates the use of gas thermal storage and oxidation technology to replace coal-fired boilers or coal-fired hot air stoves, and generates high-temperature air to achieve the purpose of heating shafts during the heating season. Although this technology has been used similarly in coal mine heating shafts, it still has the problem of fan pressure holding when the reversing valve is switched, and it is difficult to achieve uniform airflow in the heat storage chamber, which affects the operation safety of the heat storage oxidation device. In the process of combining the middle and rear heat exchangers, load fluctuations are prone to occur, which makes it difficult to control and adjust the system. The thermal energy utilization efficiency of the existing gas thermal storage oxidation system is low, and due to the cold winter climate in northern mines, the gas transportation system, gas mixing system and instrumentation actuators are prone to freezing, which is likely to cause safety hazards to the system operation.

Contents of the invention

In view of this, the purpose of the present invention is to provide a method for heating the wellbore with flue gas after gas heat storage and oxidation, which can significantly improve the heat energy utilization efficiency of the system, realize the reasonable distribution of heat energy utilization after gas oxidation, and effectively solve the problem of gas transportation system. The hidden danger of road icing creates favorable conditions for the popularization and application of gas heat storage and oxidation utilization technology in cold northern regions.

To achieve the above object, the present invention provides the following technical solutions:

A method for heating a wellbore with flue gas after gas heat storage and oxidation, comprising the following steps:

1) Drainage gas is mixed with air and sent to the gas thermal storage oxidation device;

2) The mixed gas is preheated in the regenerative oxidation device, and an oxidation reaction occurs in the combustion chamber to generate high-temperature flue gas;

3) The generated heat maintains the heat balance of the oxidation device itself. Part of the flue gas enters the gas/gas heat exchanger to heat the shaft, and the other part of the flue gas is sent to the gas/water heat exchanger or the boiling water boiler to generate hot water;

4) After heat exchange by the heat exchanger, the high-temperature flue gas flows back to the mixing section of gas and air for primary mixing, and secondary mixing with the extraction gas in the blender, while laying insulation materials on the system pipes.

Further, it also includes adjusting and distributing the available heat after oxidation among different heat loads before step 3).

Further, in step 4), the high-temperature flue gas backflow is mixed with air at multiple points.

Further, a spoiler is added to the pipe where the high-temperature flue gas returns and air is mixed, and the spoiler is three one-third circular ring plates, which are arranged at intervals on the inner wall of the mixing pipe.

Furthermore, the regenerative oxidation device in step 2) adopts a 4-chamber structure. The upper part of the regenerator is an interconnected area, and the lower part of the pneumatic reversing valve can realize the switching between the intake and the outlet. Each time the reversing valve is switched, only There is a chamber that changes from inlet to outlet.

The beneficial effects of the present invention are: solving the hidden danger of freezing of pipelines in the transportation system after gas mixing in coal mines in winter, improving the efficiency of thermal energy recycling in the system, and optimizing the heat distribution of available flue gas after gas oxidation, improving the System thermal energy utilization efficiency.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is the schematic diagram of the inventive method;

Fig. 2 is the flowchart of the inventive method;

Fig. 3 and Fig. 4 are structural schematic diagrams of the spoiler of the method of the present invention.

Among them, 1 is a blender, 2 is a fan, 3 is a thermal storage oxidation device, 4 is a heat exchanger I, 5 is a heat exchanger II, 6 is a chimney, 7 is a pumping station, and 8 is a water seal fire arrester Explosion relief device, 9 is an automatic powder spraying explosion suppression device, 10 is an automatic explosion suppression device, 11 is a soft water processor, 12 is a feed water pump, 13 is a bypass valve, and 14 is a combustion-supporting fan.

detailed description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 1 and Figure 2, the extracted gas and air are mixed in the blender 1, after passing through the water seal fire arresting and explosion venting device 8, the automatic powder spraying explosion suppression device 9, and the automatic explosion arresting device 10, after mixing It is transported by the fan 2 to the gas thermal storage oxidation device 3, and the combustion-supporting fan 14 provides combustion-supporting air for the fuel during the cold start-up process of the gas oxidation device, and the oxidation reaction occurs, and the excess heat other than maintaining the self-heating balance of the system is converted into high-temperature flue gas. The regenerative oxidation device 3 and 13 are taken out as bypass valves, which are sent to heat exchanger I4, heat exchanger II5 and boiling water boiler for heat exchange. Heat exchanger I4 is for gas-gas heat exchange, and heat exchanger II5 is for gas-water exchange. Heat, respectively generate hot air for mixing the incoming air for shaft heating, hot water for bathing and boiling water, etc., to meet the heat load requirements of shaft heating, bathing and drinking water in coal mines, and the water after heat exchange can be recycled after being treated by the soft water processor 11 Utilize, 12 is feed water pump.

As shown in Figure 2, the gas thermal storage and oxidation device 3 has a structure of four regenerator chambers, and only one chamber changes from air intake to air outlet each time the reversing valve is switched, so no airflow will flow into the regenerator and cause the fan to The pressure is suppressed, and the relative cross-sectional area of a single regenerator is smaller, the airflow distribution is more uniform, and the oxidation effect is better. The upper part of the regenerator is designed as an interconnected area, called the combustion chamber, which is the main reaction area after the gas is preheated. The gas reacts in the oxidation device to release heat to maintain the heat balance of the system. The excess heat passes through the gas inlet on the top and outputs heat to the boiler or heat exchanger in the form of high-temperature flue gas to prepare heat medium for heating or other ways. energy utilization. The pneumatic reversing valve at the lower part of the thermal storage oxidation device can realize the switching of the air intake and output, and realize the heat transfer and balance process between the regenerators of the oxidation device.

In this embodiment, by setting up a heat regulation and distribution system, including a pneumatic control valve, a pneumatic shut-off valve, a flow meter and a monitoring system from the outlet of the oxidation device to the heat user end, the flue gas flow rate can be reasonably adjusted and monitored according to weather conditions and load fluctuations. distribution, so as to better meet the needs of various heat loads, use the flue gas after heat exchange that should have been discharged to the chimney 6, return to the air intake end, and mix through multi-point hedging to heat the air to water vapor Above the dew point temperature (generally, it can be heated to 20°C or higher), and then blended with the extraction gas in the blender 1, which increases the temperature of the blending process and the mixed delivery process gas, and through setting a reasonable Pipeline insulation measures are adopted, and insulation materials are laid on the system pipelines to avoid the hidden danger of freezing during gas mixing and transportation.

As shown in Figure 3 and Figure 4, in this embodiment, spoilers are added to the pipeline after the return flue gas is mixed to increase the mixing effect and ensure the uniformity of the gas mixing effect. The shape of the spoiler is to divide a steel plate with the same cross-section as the air duct into three parts according to the fan-shaped area. On the inner wall of the pipeline, Fig. 4 is a view along the axial direction of Fig. 3, and the three fan-shaped steel plates just surround 360° in the radial direction.

The invention realizes the "on-demand distribution" of heat after gas oxidation and the cascade utilization of high-temperature flue gas heat, provides heat energy utilization efficiency, and solves the problem of mixing and mixing after the system is applied in the heating period of northern coal mines. Hidden dangers of ice, strong technical innovation, and good practical value.

This embodiment is a coal mine in the north. It is planned to use the gas heat storage and oxidation process to replace the coal-fired boiler to realize the function of shaft heating, and provide the building heating source and the heating source of the boiling water boiler for the air shaft duty room. The average minimum temperature of the coldest month in this area in winter is -19°C, and the air intake of the shaft is 10,000Nm ³ /h. After calculation, the antifreeze heat load demand of the shaft is 4962kW, and the building heating load of the duty room of the air shaft is 600kW. The heat load of the furnace is 400kW, and the total load is 5962kW. Design a set of 100,000Nm ³ /h gas thermal storage oxidation device and supporting waste heat steam boiler. It is estimated that when the gas thermal storage oxidation device has a treatment concentration of 1.2%, the output heat is 9095kW. Considering the transportation loss and heat exchange efficiency along the way, then The output heat source heat is 6063kW, which can meet the heat load demand of existing heating shafts, heating and boiling water boilers. The process flow is shown in Figure 2. Use the flow regulating valves of steam leading to heat exchangers for heating at the wellhead, heat exchangers for heating and boiling water boilers, etc., to adjust according to their different heat load requirements, so that the heat generated by the waste heat boiler after the oxidation device is reasonable and efficient. efficient distribution. When the meteorological conditions change, the inlet air temperature rises to -10°C, and the wellbore antifreeze load drops to 2835kW. At this time, the total load of wellbore antifreeze, heating and boiling water is 3835kW, which can reduce the methane concentration to 0.8%, and the waste heat after the oxidation device The maximum heat output of the boiler is 4042kW, which can meet all heat load requirements (transport loss and heat exchange efficiency along the way have been considered). Similarly, when the inlet air temperature continues to rise, such as -4°C, the methane concentration can be reduced to 0.5, and the waste heat boiler at the rear end of the oxidation device can output heat of 2526kW (considering the transmission loss and heat exchange efficiency along the way) ), which can meet the total heat load demand of 2418kW.

At the same time, the flue gas temperature at the outlet of the waste heat boiler 9 is about 150°C, which should be discharged to the chimney 6. In this process system, part or all of it (adjust the flow rate according to actual needs, and the excess flue gas is partially discharged to the chimney 6 ) is used to heat the cold air intake in the gas extraction and mixing section, so that its temperature is higher than the water vapor dew point temperature under the local meteorological conditions, so as to avoid icing during mixing and transportation, and avoid operation accidents. The concentration of gas extracted from the coal mine is about 8%, and the mixed volume of extracted gas is 12000Nm ³ /h. When the ambient temperature is -19°C and the target temperature of the mixed gas is 21°C, the air that needs to be mixed and the backflow of smoke The air flow rates are 67000Nm ³ /h and 21000Nm ³ /h respectively; when the ambient temperature is -15°C, the mixed air and return flue gas flow rates are 69000Nm ³ /h and 19000Nm ³ /h respectively; when the ambient temperature is - At 10°C, the mixed air and return flue gas volumes are 71000Nm ³ /h and 17000Nm ³ /h respectively (assuming that when the ambient temperature changes, the return flue gas temperature remains constant, both at 150°C). According to calculation, the flue gas flow rate at the waste heat boiler outlet is about 24000Nm ³ /h, and in addition to the return flue gas, the excess flue gas is directly discharged to the chimney 6 .

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (5)

1. flue gas wellbore method after a kind of gas regenerative oxidation, it is characterised in that：Comprise the following steps：

1) mash gas extraction is blended with air, delivers to gas regenerative oxidation device；

2) mixed gas is preheated in regenerative oxidation device, and oxidation reaction occurs in combustor, produces high-temperature flue gas；

3) heat for producing maintains the heat balance of oxidation unit itself, part of smoke to enter gas gas-heat exchanger, heated well Cylinder, another part flue gas deliver to gas water heat exchanger or boiler respectively, produce hot water；

4) the blending section of the high temperature gases recirculating to gas and air after heat exchanger heat exchange, carries out mixed once, and with Mash gas extraction carries out secondary mixing in mixing machine, while system pipeline is laid insulation material.

2. flue gas wellbore method after gas regenerative oxidation according to claim 1, it is characterised in that：It is additionally included in step It is rapid 3) before available heat after oxidation is adjusted between different thermic loads and distribution.

3. flue gas wellbore method after gas regenerative oxidation according to claim 1, it is characterised in that：In step 4) In, high temperature gases recirculating carries out multiple spot with air and liquidates mixing.

4. flue gas wellbore method after gas regenerative oxidation according to claim 1, it is characterised in that：In high-temperature flue gas Backflow increases spoiler, Circular Plate of the spoiler for three piece of 1/3rd annular shape, interval with the mixed pipeline of air It is straggly to be arranged on the inwall of mixing duct.

5. flue gas wellbore method after gas regenerative oxidation according to claim 1, it is characterised in that：Step 2) in Regenerative oxidation device adopts 4 cell structures, and the top of regenerator is the region for interconnecting, the air operated reversing valve of bottom be capable of achieving into Gas and the switching of outlet, only have a room during commutation Vavle switching every time and are changed into outlet from air inlet.