A gas thermal storage oxidation multi-media cascade heat storage peak regulation method

Abstract

The present invention relates to a multi-media cascaded heat storage and peak-shaving method for gas thermal oxidation, belonging to the field of energy utilization technology. A gas oxidation device oxidizes low-concentration gas to produce high-temperature flue gas of no less than 900°C. This high-temperature flue gas is then mixed with mixed air in a mixing device to produce final low-temperature flue gas at 40-50°C. A molten salt heat exchanger heats the high-temperature flue gas with low-temperature molten salt in the molten salt heat exchanger, heating the molten salt and outputting primary low-temperature flue gas at 230-240°C. During low-temperature periods, when the high-temperature flue gas is insufficient to produce sufficient final low-temperature flue gas, some of the high-temperature flue gas is extracted from the high-temperature flue gas pipeline and mixed with cold air to produce intermediate low-temperature flue gas at 130-140°C. This intermediate low-temperature flue gas is then heat-exchanged with high-temperature molten salt in the molten salt heat exchanger to output secondary high-temperature flue gas at 350-360°C. This secondary high-temperature flue gas is then passed into the mixing device to compensate for the heat deficit of the high-temperature flue gas during low-temperature periods. This invention improves the utilization rate of gas oxidation heat supply.

Description

Technical Field

[0001] The invention belongs to the technical field of energy utilization and relates to a gas thermal storage oxidation multi-media cascade heat storage peak regulation method. Background Art

[0002] Low-concentration gas refers to coalbed methane with a methane concentration of less than 30%. Low-concentration coal mine gas is the main source of coal mine gas emissions. Due to the lack of effective utilization methods, it has been discharged in large quantities for a long time, resulting in a significant greenhouse effect trend and energy waste. It is also an important reason for the low utilization rate of coalbed methane in my country.

[0003] Thermal storage oxidation technology is currently commonly used to utilize low-concentration methane, and it has also been used industrially in coal mines. This technology not only processes methane but also outputs heat to meet various coal mine load requirements.

[0004] However, if gas thermal storage oxidation technology is used to supply various loads in coal mines, when the gas source is insufficient to meet the maximum load, the system needs to be equipped with auxiliary load supply equipment. When the load fluctuates greatly, it will lead to problems such as low utilization efficiency of the oxidation heating system. Taking the gas thermal storage oxidation heating system as an example, when the gas source is insufficient, the output capacity of the gas thermal storage oxidation heating system is insufficient to meet the entire heating load, and it is necessary to supplement it with gas boilers or other heating methods. At the same time, due to the large difference in average temperature between day and night during the heating season, although the scale of the gas thermal storage oxidation heating system cannot meet the maximum load demand at night, the output capacity of the gas thermal storage oxidation heating system during the day is sufficient, resulting in a certain amount of "waste" of heating capacity. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a gas thermal storage oxidation multi-media cascade heat storage peak regulation method to improve the utilization efficiency of the gas oxidation heating system.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A gas thermal storage and oxidation multi-media cascade heat storage and peak regulation method comprises the following steps: oxidizing low-concentration gas through a gas oxidation device to generate high-temperature flue gas of not less than 900°C; mixing the high-temperature flue gas with mixed air through a mixing device to generate final low-temperature flue gas of 40-50°C; and exchanging heat between the high-temperature flue gas and the low-temperature molten salt in the molten salt heat exchange device through a molten salt heat exchange device to heat the molten salt and output primary low-temperature flue gas of 230-240°C. During a low-temperature period, when the high-temperature flue gas is insufficient to generate sufficient final low-temperature flue gas, part of the high-temperature flue gas is extracted from the high-temperature flue gas pipeline and mixed with cold air to generate intermediate low-temperature flue gas of 130-140°C; exchanging heat between the intermediate low-temperature flue gas and the high-temperature molten salt in the molten salt heat exchange device to output sub-high-temperature flue gas of 350-360°C, and passing the sub-high-temperature flue gas into the mixing device to fill the heat shortage of the high-temperature flue gas during the low-temperature period.

[0008] Optionally, a molten salt electric heater is provided as a backup heating device to fill the shortage of heat from the high-temperature flue gas during low-temperature periods.

[0009] Optionally, the molten salt in the molten salt heat exchange device is 95% HITEC-5% Na2CO3 molten salt.

[0010] Optionally, the primary low-temperature flue gas is used for heat supply including boiler heating.

[0011] Optionally, the design parameters of the molten salt heat exchange device are determined according to the maximum load demand.

[0012] Optionally, the power of the molten salt electric heater is not less than 800 kW.

[0013] Optionally, the final low-temperature flue gas is used for heat supply including wellbore heating.

[0014] The beneficial effect of the present invention is that by using the molten salt heat exchange device to store energy during high-temperature periods and releasing energy during low-temperature periods, peak shaving and valley filling of gas oxidation heating is achieved, thereby improving the utilization rate of gas oxidation heating.

[0015] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0017] Figure 1 The figure is a schematic diagram of a gas thermal storage oxidation multi-media cascade heat storage peak regulation method according to the present invention. DETAILED DESCRIPTION

[0018] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0019] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0020] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0021] See Figure 1 , a gas thermal storage and oxidation multi-media cascade heat storage and peak regulation method, wherein low-concentration gas is oxidized by a gas oxidation device to produce high-temperature flue gas of not less than 900°C, and the high-temperature flue gas is mixed with mixed air by a mixing device to produce final low-temperature flue gas of 40-50°C for heat supply including wellbore heating, and the high-temperature flue gas is heat-exchanged with the low-temperature molten salt in the molten salt heat exchange device by a molten salt heat exchange device to heat the molten salt and output primary low-temperature flue gas of 230-240°C; during the low-temperature period, when the high-temperature flue gas is insufficient to produce sufficient final low-temperature flue gas, part of the high-temperature flue gas is extracted from the high-temperature flue gas pipeline and mixed with cold air to produce intermediate low-temperature flue gas of 130-140°C, and the intermediate low-temperature flue gas is heat-exchanged with the high-temperature molten salt in the molten salt heat exchange device to output sub-high-temperature flue gas of 350-360°C, and the sub-high-temperature flue gas is passed into the mixing device to fill the heat shortage of the high-temperature flue gas during the low-temperature period.

[0022] The present invention utilizes a molten salt heat exchange device to store energy during high-temperature periods and releases energy during low-temperature periods, thereby achieving peak shaving and valley filling of gas oxidation heat supply and improving the utilization rate of gas oxidation heat supply.

[0023] The present invention also provides a molten salt electric heater as a backup heating device to fill the shortage of heat of high-temperature flue gas during low-temperature periods.

[0024] The molten salt in the molten salt heat exchanger of this invention is 95% HITEC-5% Na2CO3 molten salt. This is because high-temperature flue gas reaches 900°C, so a molten salt with a higher melting point is preferred. Furthermore, since the required air is only 40-50°C, a molten salt with a lower freezing point is required to maximize its energy storage density, thereby reducing overall costs and improving the project's economic efficiency.

[0025] The present invention realizes the "peak shaving and valley filling" of heat load during the day and night, solves the problem of high investment and operation costs caused by excessive design capacity, and improves the utilization rate of gas oxidation heating.

[0026] This invention utilizes low-concentration gas discharged from gas pumping stations as fuel. This low-concentration gas is thermally oxidized by a gas oxidation device to eliminate methane, simultaneously generating high-temperature flue gas. This high-temperature flue gas is mixed with cold air for wellbore heating, effectively replacing existing coal-fired hot air furnaces. This effectively addresses the issue of excessive atmospheric pollutants in existing coal-fired hot air furnaces, reduces atmospheric pollutant emissions, and avoids the discharge of wastewater and solid waste. This system offers significant energy-saving and environmental benefits, while fully utilizing the discharged low-concentration gas and saving coal consumption.

[0027] The present invention provides a gas thermal storage oxidation molten salt heat storage circulation system: the design parameters of the circulation system are determined by the maximum load demand, and the control method of the molten salt heat storage peak regulation is determined according to the load fluctuation law. The system includes a gas oxidation device, a mixing device, a molten salt heat exchange device and a control system. The molten salt heat exchange device includes a high-temperature air-molten salt heat exchanger and a molten salt-hot air heat exchanger. The control system includes a molten salt peak regulation system and a molten salt circulation comprehensive safety control system.

[0028] The present invention uses a molten salt heat exchange device as a heat storage system. When the outdoor temperature is high during the day, less heat is required for wellbore antifreeze, and the excess high-temperature flue gas is sent to the high-temperature air-molten salt heat exchanger to exchange heat with the low-temperature molten salt from the low-temperature molten salt tank to heat the low-temperature molten salt. The heated molten salt enters the high-temperature molten salt tank for storage. The high-temperature flue gas is 900°C. After passing through the high-temperature air-molten salt heat exchanger, the flue gas temperature drops to 230°C, and then is sent to other areas, such as boiler heating, to facilitate later use to ensure heat demand. In addition, an 800kW molten salt electric heater is set as a backup to heat the molten salt when the flue gas heat is insufficient.

[0029] At night, when outdoor temperatures are low, the heat generated by the waste heat boiler / heat exchanger is insufficient to meet the heating needs for wellbore antifreeze. At this time, the high-temperature exothermic molten salt pump is turned on, and the high-temperature molten salt enters the molten salt-hot air heat exchanger to exchange heat with the hot air that has passed through the air preheater, producing high-temperature hot air. This is then mixed with the cold air from the mixing blower to produce hot air suitable for wellbore antifreeze. To ensure the safety of the molten salt, the air needs to be preheated. Some hot air is extracted from the high-temperature air main pipeline as another heat source to preheat the cold air. After the air is preheated to 130°C, it is sent to the heat exchanger for heat exchange with the molten salt, producing 350°C high-temperature air. This is then mixed with the mixed air to produce hot air at 40-50°C.

[0030] During the high-temperature period during the day, the present invention uses excess high-temperature flue gas to heat the molten salt through a high-temperature air-molten salt heat exchanger, and stores the waste heat of the high-temperature flue gas in the molten salt; during the low-temperature period at night, the heat energy in the high-temperature molten salt is released, and the hot air is heated through a molten salt-hot air heat exchanger and sent to the wellbore for anti-freezing, thereby meeting the electric heating needs throughout the day.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A multi-media cascade heat storage and peak-shaving method for gas thermal storage oxidation, characterized by: The low-concentration gas is oxidized by the gas oxidation device to generate high-temperature flue gas of not less than 900°C, the high-temperature flue gas is mixed with the mixing air by the mixing device to generate final low-temperature flue gas of 40-50°C, and the high-temperature flue gas is exchanged with the low-temperature molten salt in the molten salt heat exchange device by the molten salt heat exchange device to heat the molten salt and output primary low-temperature flue gas of 230-240°C; During the low-temperature period, when the high-temperature flue gas is insufficient to produce sufficient ultimate low-temperature flue gas, part of the high-temperature flue gas is extracted from the high-temperature flue gas pipeline and mixed with cold air to produce intermediate low-temperature flue gas at 130-140°C. The intermediate low-temperature flue gas is heat-exchanged with the high-temperature molten salt in the molten salt heat exchange device to output sub-high-temperature flue gas at 350-360°C. The sub-high-temperature flue gas is then passed into the mixing device to make up for the lack of heat in the high-temperature flue gas during the low-temperature period. The molten salt in the molten salt heat exchanger is 95% HITEC-5% Na2CO3 molten salt, and the design parameters of the molten salt heat exchanger are determined according to the maximum load demand.

2. The gas thermal storage and oxidation multi-media cascade thermal storage and peak regulation method according to claim 1, characterized in that: A molten salt electric heater is also provided as a backup heating device to fill the lack of heat from high-temperature flue gas during low-temperature periods.

3. The multi-media cascade heat storage and peak-shaving method for gas thermal storage oxidation according to claim 1 is characterized in that: The primary low-temperature flue gas is used for heat supply including boiler heating.

4. The gas thermal storage oxidation multi-media cascade thermal storage peak regulation method according to claim 2, characterized in that: The power of the molten salt electric heater is not less than 800kW.

5. The gas thermal storage oxidation multi-media cascade thermal storage peak regulation method according to claim 1, characterized in that: The final low-temperature flue gas is used for heat supply including wellbore heating.

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