Novel intermediate water circulation system for gradient utilization of mid-deep geothermal energy

Abstract

The utility model discloses a novel intermediate water circulation system for gradient utilization of mid-deep geothermal energy, which comprises a production well and a recharge well which are arranged at a mid-deep geothermal source and are communicated through a geothermal water pipe, and a first-stage plate heat exchanger, a second-stage plate heat exchanger and a third-stage plate heat exchanger are sequentially arranged on the geothermal water pipe. The heat exchange end of the first-stage plate heat exchanger is connected with a heat supply pipe network through a pipeline, and the heat supply pipe network is further connected with the heat exchange end of the first heat pump unit and the heat exchange end of the second heat pump unit. The low-heat end of the first heat pump unit, the low-heat end of the second heat pump unit, the heat exchange end of the third-stage plate heat exchanger and the heat exchange end of the second-stage plate heat exchanger are sequentially connected through a circulating water pipe, and a circulating pump is arranged on the circulating water pipe. And the circulating water pipe and the geothermal water pipe are provided with valves for controlling the second and third plate heat exchangers and the first and second heat pump units to start and stop. The system is low in investment cost, high in thermal efficiency utilization rate and low in failure rate during operation, and the operation cost of the system is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of geothermal energy heating, in particular to a novel intermediate water circulation system for cascade utilization of mid-deep geothermal energy. Background Art

[0002] Geothermal energy is a green, low-carbon renewable energy source that can be used for heating and cooling, power generation, industrial heating, planting and breeding, etc. Among them, the total amount of hydrothermal geothermal resources in the deep layer with a burial depth of about 3 kilometers is equivalent to 1.25 trillion tons of standard coal. If it is vigorously developed and used as a heat source for urban heating, it can save a lot of coal resources and reduce the emission of pollutants such as CO2. However, the existing geothermal heating system has problems such as low thermal efficiency utilization, high investment cost and operating cost, which hinders the promotion and application of deep geothermal heating technology. Summary of the invention

[0003] In order to solve the above problems, the utility model provides a novel intermediate water circulation system for cascade utilization of mid-deep geothermal energy, which can specifically adopt the following technical solutions:

[0004] The novel intermediate water circulation system for cascade utilization of medium-deep geothermal energy described in the utility model comprises a production well and a reinjection well arranged at a medium-deep geothermal source, the production well and the reinjection well being connected through a geothermal water pipe, a primary plate heat exchanger, a secondary plate heat exchanger and a tertiary plate heat exchanger being arranged in sequence on the geothermal water pipe, a heat exchange end of the primary plate heat exchanger being connected to a heat supply network through a pipeline, the heat supply network being also connected to a heat exchange end of a first heat pump unit and a heat exchange end of a second heat pump unit, a low heat end of the first heat pump unit, a low heat end of the second heat pump unit, a heat exchange end of the tertiary plate heat exchanger and a heat exchange end of the secondary plate heat exchanger being connected in sequence through a circulating water pipe, a circulating pump being arranged on the circulating water pipe, and valves for controlling the start and stop of the secondary plate heat exchanger, the tertiary plate heat exchanger, the first heat pump unit and the second heat pump unit being arranged on the circulating water pipe and the geothermal water pipe.

[0005] The geothermal water pipe is provided with a first branch pipe connected to the inlet and outlet of the low heat end of the secondary plate heat exchanger and a second branch pipe connected to the inlet and outlet of the low heat end of the tertiary plate heat exchanger. The circulating water pipe is provided with a third branch pipe connected to the inlet and outlet of the heat exchange end of the tertiary plate heat exchanger and a fourth branch pipe connected to the inlet and outlet of the low heat end of the second heat pump unit. The valve components include a first valve arranged on the first branch pipe and a second valve arranged on the geothermal water pipe near the inlet / outlet of the low heat end of the secondary plate heat exchanger, a third valve arranged on the second branch pipe and a fourth valve arranged on the geothermal water pipe near the inlet / outlet of the low heat end of the tertiary plate heat exchanger, a fifth valve arranged on the third branch pipe and a sixth valve arranged on the circulating water pipe near the inlet / outlet of the heat exchange end of the tertiary plate heat exchanger, and a seventh valve arranged on the fourth branch pipe and an eighth valve arranged on the circulating water pipe near the inlet / outlet of the low heat end of the second heat pump unit.

[0006] Two circulating pumps are arranged in parallel and are located on the circulating water pipe between the third branch pipe and the fourth branch pipe.

[0007] The novel intermediate water circulation system for cascade utilization of medium-deep geothermal energy provided by the utility model has low investment cost, high thermal efficiency utilization rate, low failure rate during equipment operation, and greatly reduces system operation cost.

[0008] Compared with the prior art, the advantages of the utility model are as follows:

[0009] 1) A three-stage heat exchange structure consisting of "first-stage plate heat exchanger, second-stage plate heat exchanger + first heat pump unit, third-stage plate heat exchanger + second heat pump unit" is set between the geothermal well and the heating pipe network to release the heat of geothermal water in steps, extract geothermal energy in a cascaded manner, and maximize the utilization of geothermal water thermal efficiency;

[0010] 2) A series-type intermediate water circulation system is set up between the "secondary plate heat exchanger, the first heat pump unit, the third-stage plate heat exchanger and the second heat pump unit", which saves the number of circulating water pumps and reduces the investment in pump equipment; at the same time, when performing indirect heat exchange between water and heat, the more expensive heat pump unit equipment is isolated from the more corrosive geothermal water, which prevents the geothermal water from corroding the heat pump unit, ensures the operating stability of the system, extends the service life of the equipment, and greatly reduces the inspection and maintenance costs of the system;

[0011] 3) By rationally setting valves on the system pipelines, the start and stop status of the plate heat exchanger and heat pump unit can be freely adjusted according to the heating heat load demand, which not only reduces the operating cost of the system, but also allows the use of phased investment and construction to reduce equipment idle rate, shorten investment payback period, and improve project profitability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0013] 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.

[0014] like Figure 1 As shown, the novel intermediate water circulation system for the stepwise utilization of mid-deep geothermal energy described in the utility model comprises a production well A and a reinjection well B arranged at the mid-deep geothermal source, the production well A and the reinjection well B are connected through a geothermal water pipe 1, and the geothermal water pipe 1 is sequentially connected to the low-heat ends of the primary plate heat exchanger 2, the secondary plate heat exchanger 3 and the tertiary plate heat exchanger 4. The heat exchange end of the primary plate heat exchanger 2 is connected to the heating network through a pipeline, and at the same time, the heat exchange end of the first heat pump unit 5 and the heat exchange end of the second heat pump unit 6 are also connected to the heating network. The low heat end of the first heat pump unit 5, the low heat end of the second heat pump unit 6, the heat exchange end of the tertiary plate heat exchanger 4 and the heat exchange end of the secondary plate heat exchanger 3 are connected in sequence through a circulating water pipe 7, on which a circulating pump 8 is provided, and the circulating water pipe 7 and the geothermal water pipe 1 are provided with valves for controlling the start and stop of the secondary plate heat exchanger 3, the tertiary plate heat exchanger 4, the first heat pump unit 5 and the second heat pump unit 6.

[0015] Specifically, the geothermal water pipe 1 is provided with a first branch pipe 11 connected to the low heat end inlet and outlet of the secondary plate heat exchanger 3 and a second branch pipe 12 connected to the low heat end inlet and outlet of the tertiary plate heat exchanger 4, and the circulating water pipe 7 is provided with a third branch pipe 71 connected to the heat exchange end inlet and outlet of the tertiary plate heat exchanger 4 and a fourth branch pipe 72 connected to the low heat end inlet and outlet of the second heat pump unit 6. The valve components include a first valve K1 arranged on the first branch pipe 11 and a valve K2 arranged on the geothermal water pipe 1 near the low heat end inlet and outlet of the secondary plate heat exchanger 3. The second valve K2 at the outlet, the third valve K3 arranged on the second branch pipe 12, and the fourth valve K4 arranged on the geothermal water pipe 1 near the low heat end inlet / outlet of the tertiary plate heat exchanger 4, the fifth valve K5 arranged on the third branch pipe 71, and the sixth valve K6 arranged on the circulating water pipe 7 near the heat exchange end inlet / outlet of the tertiary plate heat exchanger 4, and the seventh valve K7 arranged on the fourth branch pipe 72 and the eighth valve K8 arranged on the circulating water pipe 7 near the low heat end inlet / outlet of the second heat pump unit 6. The first valve K1, the second valve K2, the third valve K3 and the fourth valve K4 are mainly used to control whether the geothermal water flows to the secondary plate heat exchanger 3 and the tertiary plate heat exchanger 4, and the fifth valve K5, the sixth valve K6, the seventh valve K7 and the eighth valve K8 are mainly used to control whether the intermediate water flows to the first heat pump unit 5 and the second heat pump unit 6, and can also be associated with the start-stop interlocking system of the heat pump unit.

[0016] Typically, two circulation pumps 8 are arranged in parallel and are located on the circulation water pipe 7 between the third branch pipe 71 and the fourth branch pipe 72 .

[0017] When using the utility model, generally, the appropriate working mode should be selected according to the heating load demand, so as to achieve the purpose of energy saving and high efficiency. The details are as follows:

[0018] Working mode 1: In late winter, when the heating heat load demand is the largest, the system runs at full load, and all plate heat exchangers and heat pump units are in the open state. At this time, the second valve K2, the fourth valve K4, the sixth valve K6, and the eighth valve K8 need to be opened, and the first valve K1, the third valve K3, the fifth valve K5, and the seventh valve K7 need to be closed.

[0019] Working mode 2: At the beginning and end of winter heating, when the heating heat load demand is relatively small, the second valve K2, the third valve K3, the fifth valve K5, and the seventh valve K7 can be opened, and the first valve K1, the fourth valve K4, the sixth valve K6, and the eighth valve K8 can be closed, so that the first-stage plate heat exchanger 2, the second-stage plate heat exchanger 3 and the first heat pump unit 5 are in working state, and the third-stage plate heat exchanger 4 and the second heat pump unit 6 are in a stopped state.

[0020] Working mode three: At the beginning and end of winter heating, in addition to natural conditions, if there are human factors (such as phased construction of the community, low occupancy rate of the community, etc.) that cause the heating heat load demand to further decrease, the first valve K1 and the third valve K3 can be opened, and the second valve K2, the fourth valve K4, the fifth valve K5, the sixth valve K6, the seventh valve K7 and the eighth valve K8 can be closed, so that only the primary plate heat exchanger 2 is in working state, and other plate heat exchangers and heat pump units are in a stopped state.

[0021] Based on the above working mode, for residential communities that are large in scale and built in phases, the geothermal energy utilization system described in the utility model can also be constructed in phases as the community construction progresses. For example, other equipment except the three-stage plate heat exchanger 4 and the second heat pump unit 6 can be installed first, and the working mode 2 or working mode 3 can be used to put it into operation first. After obtaining economic benefits, it can be decided whether to invest in the construction of other equipment based on actual needs, thereby reducing the project investment amount, shortening the investment recovery period, and improving the project rate of return.

[0022] It should be noted that, in the description of the present invention, terms indicating orientation or positional relationships, such as "front", "rear", "left", "right", "vertical", "horizontal", "inside", "outside", etc., are based on the orientation or positional relationships shown in the drawings and 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

Claims

1. A novel intermediate water circulation system for cascade utilization of mid-deep geothermal energy, characterized by: It includes a production well and a reinjection well arranged at a medium-deep geothermal source, the production well and the reinjection well are connected through a geothermal water pipe, and a primary plate heat exchanger, a secondary plate heat exchanger and a tertiary plate heat exchanger are arranged in sequence on the geothermal water pipe, the heat exchange end of the primary plate heat exchanger is connected to a heat supply network through a pipeline, and the heat supply network is also connected to a heat exchange end of a first heat pump unit and a heat exchange end of a second heat pump unit, the low heat end of the first heat pump unit, the low heat end of the second heat pump unit, the heat exchange end of the tertiary plate heat exchanger and the heat exchange end of the secondary plate heat exchanger are connected in sequence through a circulating water pipe, a circulating pump is arranged on the circulating water pipe, and valves for controlling the start and stop of the secondary plate heat exchanger, the tertiary plate heat exchanger, the first heat pump unit and the second heat pump unit are arranged on the circulating water pipe and the geothermal water pipe.

2. The novel intermediate water circulation system for cascade utilization of mid-deep geothermal energy according to claim 1 is characterized by: The geothermal water pipe is provided with a first branch pipe connected to the inlet and outlet of the low heat end of the secondary plate heat exchanger and a second branch pipe connected to the inlet and outlet of the low heat end of the tertiary plate heat exchanger. The circulating water pipe is provided with a third branch pipe connected to the inlet and outlet of the heat exchange end of the tertiary plate heat exchanger and a fourth branch pipe connected to the inlet and outlet of the low heat end of the second heat pump unit. The valve components include a first valve arranged on the first branch pipe and a second valve arranged on the geothermal water pipe near the inlet / outlet of the low heat end of the secondary plate heat exchanger, a third valve arranged on the second branch pipe and a fourth valve arranged on the geothermal water pipe near the inlet / outlet of the low heat end of the tertiary plate heat exchanger, a fifth valve arranged on the third branch pipe and a sixth valve arranged on the circulating water pipe near the inlet / outlet of the heat exchange end of the tertiary plate heat exchanger, and a seventh valve arranged on the fourth branch pipe and an eighth valve arranged on the circulating water pipe near the inlet / outlet of the low heat end of the second heat pump unit.

3. The novel intermediate water circulation system for cascade utilization of mid-deep geothermal energy according to claim 2 is characterized by: Two circulating pumps are arranged in parallel and are located on the circulating water pipe between the third branch pipe and the fourth branch pipe.

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