Drilling heat supply system based on medium-deep geothermal energy

Abstract

The invention discloses a drilling heat supply system based on medium-deep geothermal energy, and belongs to the field of geothermal energy utilization. The system comprises a heat pump, a circulatingpump, an outer pipe, an inner pipe, a medium reversing structure and a shallow heat exchange and medium-deep heat exchange conversion structure. According to the system, circulating power is providedthrough the circulating pump, heat conduction media circulate in the outer pipe and the inner pipe to achieve exchange of medium-deep terrestrial heat, and meanwhile, through the medium reversing structure, when the medium backflow temperature is lower than the temperature of the outer pipe, the flowing position of the media is switched from the outer pipe to the inner pipe, so as to solve the problem that the rising effect of the heated media hinders the operation of the media and increases the energy consumption of the circulating pump; and in summer, the shallow heat exchange and medium-deep heat exchange conversion structure is utilized to act, so that only upper sections of the inner pipe and the outer pipe work, heat exchange of shallow low-temperature terrestrial heat is carried out, and summer cooling can conveniently improve the utilization degree of a coaxial double-pipe heat exchanger composed of the outer pipe and the inner pipe.

Description

technical field [0001] The invention relates to the field of geothermal energy utilization, in particular to a drilling heating system based on mid-deep geothermal energy. Background technique [0002] Medium-deep geothermal heat is generally buried between 2,000 and 4,000 meters deep. The mid-to-deep geothermal heating system is mainly used to extract mid-to-deep geothermal heat. The heat source is the mid-to-deep crustal rock and soil. Drilling, the drilling depth is 2000-4000 meters underground, the drilling diameter is 200mm, the metal heat exchanger made of special materials is installed, the heat exchange well is closed, the liquid heat exchange medium is filled, and the heat exchange medium extracts the The heat is transmitted to the heat pump equipment room, and then distributed to the end users. This technology has a higher heat source temperature (the heat source of the rock mass below 2000m underground can reach 70°C) and is constant. The heat exchange area of ​​a...

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Problems solved by technology

[0003] The existing mid-deep geothermal energy drilling heating system has the following problems: 1. The existing mid-deep geothermal heat often uses coaxial casings as downhole heat exchangers, and heat pumps are used as ground heat exchange elements. Finally, the temperature of the return water flowing back into the outer tube of the coaxial casing is usually around 35 degrees. With the deepening of the formation depth, the temperature of the outer tube of the coaxial casing will gradually increase. At 35 degrees, the outer tube of the coaxial casing will heat the heat exchange medium inside. After the medium is heated, it will generate upward convection, which will hinder the operation of the downwardly moving medium and increase the circulation for medium circulation. For the energy consumption of the pump, in the prior art, the downwardly flowing medium is introduced into the inner tube of the coaxial sleeve on one side, and the outer tube of the coaxial sleeve guides the medium into the upper inner tube of the coaxial sleeve on the other side to realize The reversing of the flow direction of the medium allows the medium to go down from the inner tube and up from the outer tube to solve the problem of heat convection hindering the operation of the medium, but the way of reversing the medium will cause a dead zone in the operation of the medium, which will affect the heat transfer; 2. The existing same The shaft-tube heat exchanger is composed of two smooth tubular structures, and the medium will not be disturbed when it moves inside, so it is easy to generate a temperature difference between the inner and outer layers of the medium, which affects the heat exchange and storage of the medium; 3. Existing Due to the large temperature difference between the outer tube and the inner tube in the upper part of the coaxial casing heat exchanger, the heat conduction of the medium between the inner and outer tubes will affect the heat exchange efficiency of the heat exchanger; 4. The existing medium-depth heat exchanger Because it uses mid-deep geothermal heat for heat exchange, due to the high temperature of mid-deep geothermal heat, it cannot use its heat exchange for cooling in summer, which makes the mid-deep heat exchanger idle in summer, reducing the use efficiency of the mid-deep heat exchanger

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