Heat supply system based on hydrothermal type middle-deep layer terrestrial heat

Abstract

The utility model discloses a heat supply system based on hydrothermal type middle-deep layer terrestrial heat, which comprises a production well, a recharge well, a soft water supply unit, a heat supply unit, a first-stage heat exchanger and a second heat exchange unit, and the second heat exchange unit comprises a second-stage heat exchanger and a first heat pump unit. A first circulation loop is formed between the secondary heat exchanger and the first heat pump unit through a pipeline; the primary heat exchanger and the secondary heat exchanger are connected in series by the production well through a geothermal water supply pipeline; the secondary heat exchanger is communicated with the recharge well through a geothermal water return pipeline; a hot water outlet of the first-stage heat exchange channel is divided into two paths, one path is connected with a municipal primary network hot water supply pipeline, and the other path is connected with the heat supply unit. Heat of geothermal water is absorbed through three-stage heat exchange, the heat pump technology is coupled, the utilization rate of heat energy of the geothermal water and the water supply temperature of a municipal primary network are increased, and the operation cost of the whole system is reduced; and the heating duration of the heating unit in the whole heating season is shortened to a certain extent through efficient conversion of geothermal energy.

Description

Technical Field

[0001] The utility model relates to the field of municipal heating, in particular to a heating system based on hydrothermal medium-deep geothermal heat. Background Art

[0002] As a non-carbon-based clean energy, geothermal energy has a lot of advantages such as continuity, stability, and exploitable resources, and has broad application prospects in the field of heating. Geothermal energy includes 0-200m shallow layer, 200-1000m shallow hot water layer (sandstone), 1000-3000m medium-deep layer and 3000-5000m deep layer. The thermal energy water temperature of the shallow hot water layer is not high and it is not easy to recharge, which limits its application; the thermal energy temperature of the first heat reservoir in the medium-deep layer of 1000-3000m is high and the water volume is large, which is an important research object in the field of heating in recent years.

[0003] Medium-deep geothermal is divided into hydrothermal type and dry hot rock type (also known as "medium-deep non-interference"). Hydrothermal medium-deep geothermal technology is to directly extract medium-deep geothermal water as a heat source by drilling into medium-deep rock formations, and the heat is extracted by the ground system for heating ground buildings. The utilization principle of the existing demonstration projects that have been put into use is "taking heat without taking water, and fully enclosed recharge", which has also been proven to be mature, reliable, and sustainable. However, the existing medium-deep geothermal heating technology generally has problems such as single heating, inability to coordinate heating, low heat source utilization, and poor complementary coupling with other energy sources. Summary of the invention

[0004] In view of this, the utility model proposes a heating system based on hydrothermal medium-deep geothermal energy, which improves the utilization rate of geothermal energy on the basis of meeting the heating demand of the municipal primary network.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model discloses a heating system based on hydrothermal medium-deep geothermal energy, comprising a production well, a reinjection well, a soft water supply unit, a heating unit, and a primary heat exchanger and a second heat exchange unit, wherein the second heat exchange unit comprises a secondary heat exchanger and a first heat pump unit, wherein a first circulation loop is formed between the secondary heat exchanger and the first heat pump unit through a pipeline, and the first circulation loop is provided with a first circulation pump; the production well connects the primary heat exchanger and the secondary heat exchanger in series in sequence through a geothermal water supply pipeline, and the secondary heat exchanger is connected to the reinjection well through a geothermal water return pipeline; the hot water outlet of the primary heat exchange channel is divided into two routes, one route is connected to the hot water supply pipeline of the municipal primary network and has a sixth valve, and the other route is connected to the heating unit; the hot water return pipeline is connected to the return water port of the primary heat exchanger after heat exchange by the first heat pump unit, and the water supply pipeline of the soft water supply unit is connected to the hot water return pipeline.

[0007] The beneficial effects are: the utility model adopts gradient heat exchange, uses geothermal energy to exchange heat with soft water in succession, improves the utilization rate of medium and deep geothermal energy, and thus reduces the consumption of carbon-based energy, and saves energy and protects the environment. The utility model uses three-stage heat exchange to absorb the heat of geothermal water, and couples with heat pump technology, which greatly improves the utilization rate of geothermal water heat energy, and increases the water supply temperature of the municipal primary network, thereby reducing the operating cost of the entire system; in addition, the efficient conversion of geothermal energy also reduces the heating time of the heating unit in the entire heating season to a certain extent, further saving carbon-based energy, low-carbon emission reduction, and green environmental protection.

[0008] Preferably, the utility model also includes a third heat exchange unit, which has a three-stage heat exchanger and a second heat pump unit, a second circulation loop is formed between the three-stage heat exchanger and the second heat pump unit through a pipeline, and a second circulation pump is provided on the second circulation loop; the geothermal outlet of the secondary heat exchanger is divided into two paths, the first path is connected to the three-stage heat exchanger and a second valve is arranged on the first path, and the second path is connected to the geothermal return water pipeline and the branch has a first valve; the three-stage heat exchanger is connected to the geothermal return water pipeline, and a third valve is provided at the geothermal water outlet of the three-stage heat exchanger; a tenth valve is provided on the pipeline between the second path and the geothermal water outlet of the three-stage water heater; the hot water return water pipeline is divided into two paths, one path is connected to the first heat pump unit and the path has an eleventh valve, and the other path is connected to the second heat pump unit and the path has a fifth valve, and the hot water outlet of the second heat pump unit is connected to the first heat pump unit through a pipeline and the pipeline has a fourth valve. The beneficial effect is that the utility model adopts three-level gradient heating and determines the working state of the third heat exchange unit according to the outdoor temperature to meet the heating demand of the municipal primary network.

[0009] Preferably, the heating unit includes an absorption heat pump unit and a gas-fired hot water boiler, a branch of the hot water supply pipeline is connected to the absorption heat pump unit and has an eighth valve on the branch; the outlet of the gas-fired hot water boiler is connected to the municipal primary network hot water supply pipeline, and the hot water outlet of the gas-fired hot water boiler is provided with a seventh valve; the water source end of the municipal primary network water supply pipeline has a first temperature sensor.

[0010] Preferably, the hot air channel of the gas-fired hot water boiler is connected to an absorption heat pump unit to recover the waste heat of the flue gas of the gas-fired hot water boiler and improve the thermal efficiency of the gas-fired hot water boiler.

[0011] Preferably, a second temperature sensor is provided on the hot water supply pipeline close to the primary heat exchanger.

[0012] Preferably, the soft water supply unit comprises a softened water device, a softened water tank and a water supply pump which are sequentially connected through a water supply pipeline, the outlet of the water supply pump is connected to the hot water return pipeline, and a ninth valve is provided at the inlet of the water supply pipeline to provide sufficient circulating water for the hot water supply and hot water return during the trial operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0014] The following is a detailed description of an embodiment of the utility model in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the utility model, and a detailed implementation method and a specific operation process are given, but the protection scope of the utility model is not limited to the following embodiment.

[0015] It should be noted that, in the description of the present utility model, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0016] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" that may appear should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0017] like Figure 1As shown, the heating system based on hydrothermal medium-deep geothermal energy described in the utility model includes a production well 1, a reinjection well 2, a soft water supply unit, a heating unit, a primary heat exchanger E1 and a second heat exchange unit. The production well 1 is provided with a production pump P4 to provide power for the extraction of geothermal water; the reinjection well 2 is provided with a reinjection pump P5 to provide power for the reinjection of geothermal water; the soft water supply unit includes a softened water device 3, a softened water tank 4 and a make-up pump P3 connected in sequence through a make-up pipe L1, the outlet of the make-up pump P3 is connected to the hot water return pipe L2, the make-up pipe L1 is externally connected to tap water and has a ninth valve F9 at its inlet, the softened water device 3 can soften the tap water and circulate it with soft water; in the initial stage of operation, the make-up pump P3 is used to pump softened water into the hot water return pipe L2; during operation, municipal heating inevitably suffers from water loss, and the make-up pump P3 can be used to replenish water to ensure the circulating water volume; the second heat exchange unit includes a secondary exchange A first circulation loop is formed between the heat exchanger E2 and the first heat pump unit R1, and between the secondary heat exchanger E2 and the first heat pump unit R1 through pipelines, and the first circulation loop is provided with a first circulation pump P1; the production well 1 connects the primary heat exchanger E1 and the secondary heat exchanger E2 in series in sequence through the geothermal water supply pipeline L3 (a desander 7 is provided on the geothermal water supply pipeline L3), and the secondary heat exchanger E2 is connected with the reinjection well 2 through the geothermal return water pipeline L4 (a self-cleaning filter 5 is provided on the geothermal return water pipeline L4); the hot water outlet of the primary heat exchanger E1 is divided into two routes, one of which is connected to the municipal primary network hot water supply pipeline and has a sixth valve F6, and the other is connected to the heating unit; the hot water return water pipeline L2 (a municipal primary network circulation pump P6 is provided on the hot water return water pipeline L2) is connected with the return water port of the primary heat exchanger E1 after heat exchange through the first heat pump unit R1, and the water supply pipeline of the soft water supply unit is connected with the hot water return water pipeline L2. In actual operation, the geothermal water enters the primary heat exchanger E1 and then the secondary heat exchanger E2, and then flows back to the reinjection well 2; the hot water return pipe L2 first enters the first heat pump unit R1, and then enters the primary heat exchanger E1 after heat exchange, and exchanges heat with the hot water flowing through the primary heat exchanger E1, and can obtain 75°C hot water, which is directly supplied to the municipal primary network hot water supply pipeline, realizing the full utilization of geothermal energy;

[0018] In addition, a first circulation loop is formed between the secondary heat exchanger E2 and the first heat pump unit R1. When the geothermal water passes through the secondary heat exchanger E2, it can continue to absorb the heat of the geothermal water through the first circulation loop and transfer it to the softened water flowing through the first heat pump unit R1, so that the temperature of the softened water rises to about 55°C, thereby increasing the temperature of the softened water entering the primary heat exchanger E1, thereby achieving full utilization of the heat of the mid-deep layer water.

[0019] Combination Figure 1It can be seen that the utility model also includes a third heat exchange unit, which has a three-stage heat exchanger E3 and a second heat pump unit R2. A second circulation loop is formed between the three-stage heat exchanger E3 and the second heat pump unit R2 through a pipeline, and a second circulation pump P2 is provided on the second circulation loop; the geothermal water outlet of the secondary heat exchanger E2 is divided into two paths, the first path is connected to the three-stage heat exchanger E3 and a second valve F2 is provided on the first path, and the second path is connected to the geothermal return water pipeline L4 and the branch has a first valve F1, that is, the geothermal water flowing out of the secondary heat exchanger E2 enters the three-stage heat exchanger E3, and the second circulation loop and the second heat pump unit R2 are used to heat the low-temperature softened water to improve the utilization rate of geothermal heat. When the return temperature of the softened water is high, the geothermal water flowing out of the secondary heat exchanger E2 can directly enter the recharging well 2; a twelfth valve F12 is provided between the geothermal inlet and the geothermal outlet of the secondary heat exchanger E2;

[0020] The three-stage heat exchanger E3 is connected to the geothermal return water pipeline L4, and the geothermal water outlet of the three-stage heat exchanger E3 is provided with a third valve F3; the pipeline between the second route and the geothermal water outlet of the three-stage heat exchanger E3 is provided with a tenth valve F10; the hot water return water pipeline L2 is divided into two routes, one route is connected to the first heat pump unit R1 and has an eleventh valve F11, and the other route is connected to the second heat pump unit R2 and has a fifth valve F5, and the hot water outlet of the second heat pump unit R2 is connected to the first heat pump unit R1 through a pipeline and has a fourth valve F4 on the pipeline. That is, the hot water return water pipeline L2 can directly enter the first heat pump unit R1 through one route, and enter the primary heat exchanger E1 through the second heat pump unit R2 and the first heat pump unit R1 through the other route, which can be flexibly selected according to actual conditions.

[0021] In the utility model, the utility model utilizes three-stage heat exchange to absorb the heat of geothermal water, and couples the heat pump technology, which greatly improves the utilization rate of geothermal water thermal energy and increases the water supply temperature of the municipal primary network, thereby reducing the operating cost of the entire system; in addition, the efficient conversion of geothermal energy also reduces the heating time of the heating unit in the entire heating season to a certain extent, further saving carbon-based energy, low-carbon emission reduction, and green environmental protection.

[0022] In actual engineering, the utility model is a three-stage gradient heat exchange, and of course it can also be a four-stage gradient heat exchange. Among them, the first-stage heat exchanger E1, the second-stage heat exchanger E2 and the third-stage heat exchanger E3 are preferably plate heat exchangers, and the first heat pump unit R1 and the second heat pump unit R2 are preferably single-effect lithium bromide gas absorption heat pumps.

[0023] Combination Figure 1It can be seen that the heating unit includes an absorption heat pump unit R3 (preferably a hot water + gas composite absorption heat pump) and a gas hot water boiler 6. A branch of the hot water supply pipeline L5 is connected to the absorption heat pump unit and has an eighth valve F8 on the branch. The outlet of the gas hot water boiler 6 is connected to the municipal primary network hot water supply pipeline, and the hot water outlet of the gas hot water boiler 6 has a seventh valve F7. The water source end (i.e., A) of the municipal primary network water supply pipeline has a first temperature sensor T1 for monitoring the municipal primary network hot water supply pipeline. The heating temperature of the circuit; a second temperature sensor T2 is arranged on the hot water supply pipeline near the primary heat exchanger E1 (i.e., at B), which is used for the hot water supply temperature of the primary heat exchanger E1; a third temperature sensor T3 is arranged at the geothermal water outlet of the secondary heat exchanger E2 (i.e., at C), which is used to monitor the return water temperature of the geothermal water; a fourth temperature sensor T4 is arranged at the geothermal water outlet of the tertiary heat exchanger (i.e., at D), which is used to monitor the return water temperature of the geothermal water, so as to determine the working state of the third heat exchange unit according to the return water temperature.

[0024] In actual operation, the hot air channel of the gas-fired hot water boiler 6 is connected to the absorption heat pump unit R3. The absorption heat pump unit R3 absorbs the flue gas heat of the gas-fired hot water boiler 6 and then discharges the cold air into the chimney of the gas-fired hot water boiler 6, thereby utilizing the waste heat of the gas-fired hot water boiler 6 and improving the utilization rate of the gas-fired hot water boiler 6.

[0025] During actual installation, the first valve F1, the second valve F2, the third valve F3, the fourth valve F4, the fifth valve F5, the sixth valve F6, the seventh valve F7, the eighth valve F8, the ninth valve F9, the tenth valve F10, the eleventh valve F11 and the twelfth valve F12 of the utility model are all electrically controlled valves, the control input ends of these electrically controlled valves are all connected to the control output ends of the controller, and the signal output ends of the four temperature sensors are all connected to the signal input ends of the controller. Among them, the controller can be a general processor, a special processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, etc., and can also be a PLC, or an industrial computer, etc.

[0026] During the debugging and trial operation stage, first open the ninth valve F9 and the make-up pump P3 to ensure that the circulating water volume of the hot water supply and hot water return water meets the set requirements; during operation, water can be replenished by opening the ninth valve F9 and the make-up pump P3.

[0027] In the present invention, the municipal primary network hot water supply temperature range is controlled at 75-110°C, and the hot water return temperature is controlled at 45-50°C; the groundwater supply temperature is usually above 90°C.

[0028] During the operation of the system, the production pump P4 pumps the geothermal water into the primary heat exchanger E1. The initial temperature of the geothermal water is above 90°C, and it is cooled to about 65°C after heat exchange. Then it enters the secondary heat exchanger E2 for heat exchange and continues to cool down to below 40°C. The hot water return water enters the primary heat exchanger E1 after heat exchange by the heat pump unit. The hot water supply temperature coming out of the primary heat exchanger E1 is above 75°C and can be directly supplied to the municipal primary network hot water supply pipeline. When the temperature of the hot water supply from the primary heat exchanger E1 reaches the minimum limit of the set water supply temperature, the controller controls the production pump P4 to increase the flow rate, increase the water supply flow of the production well 1, until the hot water supply temperature from the primary heat exchanger E1 reaches the maximum value of the municipal primary network water supply temperature, and then the production pump P4 is adjusted down; if the position at A is still lower than the minimum value of the municipal primary network water supply temperature when the production pump P4 is in the maximum flow state, it means that the geothermal water cannot meet the heating demand of the municipal primary network, close the sixth valve F6, and stop directly supplying water to the municipal primary network; open the seventh valve F7 and the eighth valve F8, so that the hot water supply from the primary heat exchanger E1 enters the absorption heat pump and the gas hot water boiler 6 for heating and then supplies it to the municipal primary network hot water supply pipeline, that is, the gas hot water boiler 6 is used as a supplementary heat source for heat supplement. When the water source side temperature of the municipal primary network hot water supply (i.e., the temperature at B) reaches the maximum limit of the water supply temperature, open the sixth valve F6 and close the seventh valve F7 and the eighth valve F8.

[0029] At the beginning or end of heating, the outdoor temperature is high, the hot water supply temperature of the municipal primary network is low, and the return water temperature is relatively high. You can choose to close the third heat exchange unit and use the first-stage heat exchanger E1 and the second heat exchange unit for secondary heat exchange and heating; in the middle of heating, the outdoor temperature is low and the return water temperature of the municipal primary network is relatively low. At this time, you can start the third heat exchange unit and use the third-stage heat exchange and heating. Specifically: the twelfth valve F12 is a normally closed valve. When the primary side return water temperature of the secondary heat exchanger E2 (corresponding to the temperature monitored by the third temperature sensor T3) is lower than the maximum value of the reinjection temperature, the second valve F2, the third valve F3, the fourth valve F4, and the fifth valve F5 are closed, and the first valve F1 and the eleventh valve F11 are opened, and then the third heat exchange unit is closed, and the hot water return water of the municipal primary network directly enters the first heat pump unit R1 of the second heat exchange unit through the hot water return pipeline L2, and the geothermal water return water directly flows back to the reinjection well 2; when the primary side return water temperature of the secondary heat exchanger E2 is lower than the minimum value of the reinjection temperature, the twelfth valve F12 and the first valve F1 are opened, so that .... The geothermal water after heat exchange in the primary heat exchanger E1 flows directly back to the reinjection well 2 until the temperature monitored by the third temperature sensor T3 is higher than the maximum value of the reinjection temperature, and the twelfth valve F12 and the first valve F1 are closed; when the primary side return water temperature of the secondary heat exchanger E2 is higher than the maximum value of the reinjection temperature, the first valve F1 and the eleventh valve F11 are closed, and the second valve F2, the third valve F3, the fourth valve F4 and the fifth valve F5 are opened, that is, the third heat exchange unit is started, so that the geothermal water passes through the secondary heat exchanger E2 and then enters the three plate heat exchangers for heat exchange, and the hot water return directly enters the second heat pump unit R2, that is, the third heat exchange unit is started, realizing three-stage gradient heat exchange and heating. During operation, the tenth valve F10 is a normally closed valve. When the temperature monitored by the fourth temperature sensor T4 is lower than the minimum value of the re-injection temperature, the tenth valve F10 and the second valve F2 are opened, so that the geothermal water from the secondary heat exchanger E2 flows directly into the re-injection well 2, until the temperature monitored by the fourth temperature sensor T4 is higher than the maximum value of the re-injection temperature, and then the tenth valve F10 is closed.

[0030] Finally, it should be emphasized that the above is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A heating system based on hydrothermal medium-deep geothermal energy, comprising a production well, a reinjection well, a soft water supply unit, and a heating unit, characterized in that: It also includes a primary heat exchanger and a second heat exchange unit, the second heat exchange unit includes a secondary heat exchanger and a first heat pump unit, a first circulation loop is formed between the secondary heat exchanger and the first heat pump unit through a pipeline, and the first circulation loop is provided with a first circulation pump; the production well connects the primary heat exchanger and the secondary heat exchanger in series in sequence through a geothermal water supply pipeline, and the secondary heat exchanger is connected with the reinjection well through a geothermal return water pipeline; the hot water outlet of the primary heat exchange channel is divided into two paths, one path is connected with the municipal primary network hot water supply pipeline and has a sixth valve, and the other path is connected with the heating unit; the hot water return water pipeline is connected with the return water port of the primary heat exchanger after heat exchange by the first heat pump unit, and the water supply pipeline of the soft water supply unit is connected with the hot water return water pipeline.

2. The heating system based on hydrothermal medium-deep geothermal energy according to claim 1 is characterized in that: It also includes a third heat exchange unit, the third heat exchange unit has a three-stage heat exchanger and a second heat pump unit, a second circulation loop is formed between the three-stage heat exchanger and the second heat pump unit through a pipeline, and the second circulation loop has a second circulation pump; the geothermal outlet of the secondary heat exchanger is divided into two paths, the first path is connected to the three-stage heat exchanger and a second valve is arranged on the first path, and the second path is connected to the geothermal return pipeline and the second path has a first valve; the three-stage heat exchanger is connected to the geothermal return pipeline, and the geothermal water outlet of the three-stage heat exchanger is provided with a third valve; the pipeline between the second path and the geothermal water outlet of the three-stage water heater is provided with a tenth valve; The hot water return pipeline is divided into two routes, one route is connected to the first heat pump unit and has an eleventh valve, and the other route is connected to the second heat pump unit and has a fifth valve. The hot water outlet of the second heat pump unit is connected to the first heat pump unit through a pipeline and has a fourth valve on the pipeline.

3. The heating system based on hydrothermal medium-deep geothermal energy according to claim 1 is characterized in that: The heating unit includes an absorption heat pump unit and a gas-fired hot water boiler, a branch of the hot water supply pipeline is connected to the absorption heat pump unit and has an eighth valve on the branch; the outlet of the gas-fired hot water boiler is connected to the municipal primary network hot water supply pipeline, and the hot water outlet of the gas-fired hot water boiler is provided with a seventh valve; the water source end of the municipal primary network water supply pipeline is provided with a first temperature sensor.

4. The heating system based on hydrothermal medium-deep geothermal heat according to claim 3 is characterized by: The hot air channel of the gas hot water boiler is connected to the absorption heat pump unit.

5. The heating system based on hydrothermal medium-deep geothermal energy according to claim 1 is characterized in that: A second temperature sensor is arranged on the hot water supply pipeline close to the primary heat exchanger.

6. The heating system based on hydrothermal medium-deep geothermal heat according to claim 1 is characterized in that: The soft water supply unit comprises a softened water device, a softened water tank and a water supply pump which are sequentially connected via a water supply pipeline. The outlet of the water supply pump is connected to the hot water return pipeline. The inlet of the water supply pipeline is provided with a ninth valve.

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