CN113340140A

CN113340140A - Cross-season solid-liquid combined heat storage method for reducing heat loss

Info

Publication number: CN113340140A
Application number: CN202110718434.5A
Authority: CN
Inventors: 王有镗; 徐超; 李成宇; 刘旭阳; 姜朋朋; 付士宾; 何梦遥
Original assignee: Shandong Shengli Tonghai Group Dongying Tianlan Energy Saving Technology Co ltd; Shandong University of Technology
Current assignee: Shandong Shengli Tonghai Group Dongying Tianlan Energy Saving Technology Co ltd; Shandong University of Technology
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2021-09-03
Anticipated expiration: 2041-06-28
Also published as: CN113340140B

Abstract

The invention discloses a cross-season solid-liquid combined heat storage method for reducing heat loss. According to the invention, water and gravel are used as heat storage bodies, water is used as a heat storage medium and also used as a heat transfer medium in the heat storage stage, heat is sequentially stored in the water tank and the gravel, and solid-liquid heat storage is synchronously carried out; in the heat preservation stage, solid-liquid separation is carried out, and the heat dissipation mode of the heat storage body mainly takes heat conduction of gravels and heat storage boundaries as the main mode, so that the heat loss can be effectively reduced compared with solid-liquid convection heat exchange; in the heat taking stage, the heat stored in the water body and the gravels is sequentially released to a heat user through circulation.

Description

Cross-season solid-liquid combined heat storage method for reducing heat loss

Technical Field

The invention belongs to the technical field of underground heat storage and utilization, and particularly relates to a cross-season heat loss problem of solid-liquid combined heat storage.

Background

Compared with other heat storage media, water has larger specific heat capacity, and the heat exchange intensity is easy to control, so that the water body heat storage is always the main form of the underground heat storage technology. This technique generally adopts the direct excavation on ground to store up the hot water pond, lays the waterproof layer in the pond, and the top sets up floats the top structure and is used for heat preservation and thermal-insulated, relies on the buoyancy of water to support pond top structure, but this kind of structure bearing capacity is little, and the upper strata can't plant the vegetation again or build any building or structure, consequently this kind floats the occupation of land of top formula storage hot water pond and can not effectively utilized, arouses that the land use cost increases, and this brings very big degree of difficulty for this technique is promoted in the periphery of cities and towns. In order to overcome the defects of the water body heat storage technology in this respect, gravels can be added into the water body heat storage technology to enhance the supporting effect, so that the occupied area of the water pool can be utilized, and the land cost is reduced. Therefore, the invention provides a solid-liquid combined heat storage technology which mainly stores heat in a water body and assists heat in gravel storage.

For a long time, the larger heat loss is a key problem for restricting the popularization and the application of the cross-season heat storage technology. For the solid-liquid two-phase heat storage medium, the heat convection effect exists on the solid boundary, and particularly in high-temperature heat storage projects, the problem of large heat loss also exists in the cross-season long-term heat storage process. Therefore, the problem of reducing the cross-season heat loss of the solid-liquid combined heat storage system is particularly important. Firstly, a heat insulation material with better heat insulation effect can be selected or the thickness of the heat insulation layer can be increased, which is beneficial to reducing heat loss, but the method not only increases the cost, but also causes the problem of aging attenuation of the heat insulation layer under the environment of underground high pressure, high temperature and high humidity, and once the heat insulation layer is damaged, the high temperature water body can be lost, and the problem of heat loss can not be solved; secondly, the heat storage temperature can be reduced, and the temperature difference between the heat storage body and the underground environment is reduced, so that the heat loss is reduced, but the low-grade energy is limited in application, and the popularization of the technology is not facilitated.

Compared with the prior art, under the condition of meeting the heat storage requirement, the solid-liquid combined heat storage body structure and the heat storage/heat extraction mode are improved, the heat loss of the system operation is reduced from the aspect of changing the heat transfer mode in the cross-season heat preservation process, the defects caused by the measures are avoided, and the improvement of the operation efficiency of the heat storage system and the popularization of the technology are facilitated.

Disclosure of Invention

The invention aims to provide a cross-season underground solid-liquid combined heat storage method capable of reducing heat loss. In the method, water and gravel are used as heat storage bodies, water is used as a heat storage medium and also used as a heat transfer medium in a heat storage stage, heat is sequentially stored in a water tank and the gravel, and solid-liquid heat storage is synchronously carried out; in the heat preservation stage, solid-liquid separation is carried out, and the heat dissipation mode of the heat storage body mainly takes heat conduction of gravels and heat storage boundaries as the main mode, so that the heat loss can be effectively reduced compared with solid-liquid convection heat exchange; in the heat taking stage, the heat stored in the water body and the gravels is sequentially released to a heat user through circulation.

The technical scheme for realizing the purpose is as follows: the cross-season solid-liquid combined heat storage system comprises a heat storage water tank, a lower water pipe, an upper water pipe, heat storage gravels, a water injection well, a pumping well, a water-proof heat preservation layer, temperature testing gravels, a heat source, a heat taking heat exchanger, a controller, a first circulating pump, a second circulating pump, a third circulating pump, a water tank temperature sensor, a gravels temperature sensor, a water tank setting liquid level sensor, a water tank lower limit liquid level sensor, a water tank pressure sensor, a gravels layer liquid level sensor, a heat storage water supply temperature sensor, a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve, an eighth valve, a ninth valve, a tenth valve, an eleventh valve and a twelfth valve. The heat storage water tank is cylindrical, arranges in the heat storage gravel layer, heat storage water tank lower part and upper portion are arranged respectively in to next water pipe and last water pipe, the heat storage gravel is the pebble layer of 60 ~ 200mm particle diameter, and the water of being convenient for circulates at its hole, and its hole volume should be controlled and is less than 1/2 of heat storage water tank volume, arranges it to load-bearing structure with it simultaneously, will coat pressure transfer to underground, the biggest particle diameter pebble is chooseed for use to examination temperature gravel, arranges the heat storage gravel layer middle part of pumping well in, in the heat storage gravel layer is arranged in to water injection well and pumping well, and symmetric distribution is in heat storage water tank both sides, heat-insulating layer arranges in between heat storage gravel and the normal position soil, the heat source can be industry waste heat exchanger, get heat exchanger and connect heat-retaining system and heat consumer, each sensor, each valve and each circulating pump are connected to the controller, next water pipe and water injection well are connected to first circulating pump, upper hose and pumped well are connected to the second circulating pump, the water source is connected to the third circulating pump, heat storage water tank lower part is arranged in to water tank temperature sensor, also can the temperature measurement when guaranteeing the water level lower, gravel temperature sensor arranges the inside central point of examination temperature gravel in and puts, the water tank sets for level sensor and arranges set standard water level department in the water tank, water tank lower limit level sensor arranges the water tank lower part in, is not less than next water pipe tip height, water tank pressure sensor arranges the inside top of water tank in, gravel layer level sensor arranges upper portion in pumped well, second circulating pump exit position is arranged in to heat-retaining water supply temperature sensor, first valve ~ twelfth valve are normally closed solenoid valve.

The invention has the beneficial effects that: in the heat storage stage, the water tank is firstly subjected to heat storage and then gravel heat storage, so that the core heat storage status of the water tank is ensured, and the temperature difference between the inlet heat source and the outlet heat source is increased, thereby being beneficial to improving the heat storage efficiency; in the heat preservation stage, solid and liquid are separated, the boundary heat dissipation mode of the heat storage body is mainly heat conduction, and the core high-temperature heat of the heat storage of the water tank is ensured by dissipating part of heat of the gravels; in the heat extraction stage, the core heat of the water tank is extracted firstly, and then the available heat of the gravel is extracted, so that the high-grade heat storage is preferentially utilized.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

FIG. 2 is a schematic diagram of the system operation process of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

as shown in fig. 1, the underground solid-liquid combined heat storage system comprises a heat storage water tank 1, a lower water pipe 2, an upper water pipe 3, heat storage gravels 4, a water injection well 5, a water pumping well 6, a water-resisting and heat-insulating layer 7, temperature testing gravels 8, a heat source 9, a heat extraction heat exchanger 10, a controller 11, a first circulating pump P1, a second circulating pump P2, a third circulating pump P3, a water tank temperature sensor T1, a gravel temperature sensor T2, a water tank setting liquid level sensor T3, a water tank lower limit liquid level sensor T4, a water tank pressure sensor T5, a gravel layer liquid level sensor T6, a heat storage and water outlet temperature sensor T7, a first valve V1, a second valve V2, a third valve V3, a fourth valve V4, a fifth valve V5, a sixth valve V6, a seventh valve V7, an eighth valve V8, a ninth valve V9, a tenth valve V10, an eleventh valve V11, and a twelfth valve V12. Its characterized in that heat storage water tank 1 uses water as the medium storage heat, lower water pipe 2 and upper water pipe 3 supply water or draw water to heat storage water tank 1 in to realize the heat-retaining or get hot, heat-retaining gravel 4 constitutes the heat-retaining body with heat storage water tank 1 to bear the upper portion load, water injection well 5 and pumping well 6 all are furnished with the cover that permeates water, to water supply and draw water in the gravel layer, in order to realize the heat-retaining or get hot, 7 separation heat preservation of water proof heat preservation and moisture are transferred to normal position soil from heat-retaining gravel 4, temperature testing gravel 8 is used for reflecting the temperature of the regional heat-retaining gravel layer of pumping well, heat source 9 supplies the heat to the heat-retaining body, heat exchanger 10 absorbs heat from heat storage water tank 1, and releases heat to the heat user, controller 11 is through the break-make-break of accepting each valve of each sensor signal control and circulating pump, first circulating pump P1 and second circulating pump P2 provide circulation power for, third circulating pump P3 provides the moisturizing for the system, water tank temperature sensor T1 is used for monitoring temperature in the heat storage water tank, gravel temperature sensor T2 is used for monitoring the temperature in the regional heat-retaining gravel layer of pumping well, the water tank sets for level sensor T3 and is used for monitoring whether the water tank water level reaches standard setting value, water tank lower limit level sensor T4 is used for monitoring whether the water tank lacks water, water tank pressure sensor T5 is used for monitoring water tank internal pressure, gravel layer level sensor T6 is used for monitoring whether the water level reaches the default in the heat-retaining gravel layer, heat-retaining play water temperature sensor T7 is used for detecting heat-retaining system's temperature of giving water, first valve V1 ~ twelfth valve V12 is used for realizing pressure release functions such as system's heat-retaining, getting heat, moisturizing, pressure release through the cooperation.

The working principle of the invention is as follows: as shown in fig. 2, the system working process sequentially includes a heat storage mode, a heat preservation mode, and a heat extraction mode, and has a water replenishing function and a pressure releasing function to assist the system in working, and the working principle of each mode and function of the invention is described with reference to fig. 1 and fig. 2.

A heat storage mode: this mode stores heat from the heat source into the water tank and gravel bed by the flow of circulating water through the equipment path: 1 → 2 → P1 → V1 → 5 → 4 → 6 → V2 → P2 → V7 → 9 → V3 → 3 → 1. The specific implementation mode is as follows: in the initial state, the heat storage water tank 1 is filled with water, all the circulating pumps and valves are in the closed state, the controller 11 sends an opening command to the first valve V1 and the first circulating pump P1, water in the water tank is sucked into the first circulating pump P1 through the lower water pipe 2, enters the water injection well 5 through the first valve V1 and enters the water pumping well 6 through the pores of the heat storage gravel 4, when the water level in the pumping well 6 reaches the working preset value, the controller 11 receives a signal of a gravel layer liquid level sensor T6, sends an opening instruction to the second valve V2, the third valve V3, the seventh valve V7 and the second circulating pump P2, water enters the heat source 9 from the pumping well 6 through the second valve V2, the second circulating pump P2 and the seventh valve V7, the water temperature is increased after heat absorption, and then passes through the third valve V3, and the heat returns to the heat storage water tank 1 through the upper water pipe 3, and after repeated circulation, the heat is continuously stored in the heat storage water tank 1 and the heat storage gravel 4 through the heat source 9.

A heat preservation mode: in the heat storage mode, when the temperature of the heat storage body reaches a set value, the system enters a heat preservation mode. This mode is first to transfer gravel pore water to the water tank, and the circulating water flows through the equipment route and is: 4 → 6 → V2 → P2 → V7 → 9 → V3 → 3 → 1. The specific implementation mode is as follows: when the temperatures of the heat storage water tank 1 and the heat storage gravels 4 reach the set temperatures, the controller 11 receives signals of a water tank temperature sensor T1 and a gravel temperature sensor T2 and sends closing commands to the first circulating pump P1 and the first valve V1, so that no water is injected into the water injection well 5 any more, water in the heat storage gravels 4 is pumped out from the water pumping well 6 and passes through the second valve V2, the second circulating pump P2, the seventh valve V7, the heat source 9 and the third valve V3 to enter the heat storage water tank 1 through the upper water pipe 3 until the water in the heat storage gravels 4 completely enters the heat storage water tank 1, and at the moment, the controller 11 receives no-flow passing signals of the second circulating pump P2 and sends closing commands to the second circulating pump P2 and the second valve V2. And after the gravel pore water is transferred to the water tank, the system judges whether water is required to be supplemented. If the water level in the heat storage water tank 1 is lower than the standard set value, the controller 11 sets a signal of a liquid level sensor T3 to the water tank, and the system starts a water supplementing function.

After the moisturizing stops, controller 11 sends the instruction of closing to all valves, detects the water tank temperature simultaneously, if the temperature is less than the settlement temperature, then carries out independent heat-retaining to the water tank, and the circulating water flows through the equipment route and is: 1 → 2 → P1 → V8 → 9 → V3 → 3 → 1. The specific implementation mode is as follows: when the test value of the water tank temperature sensor T1 is lower than the set value, the controller 11 sends an opening instruction to the first circulating pump P1, the third valve V3 and the eighth valve V8, water passes through the first circulating pump P1, the eighth valve V8, the heat source 9 and the third valve V3 from the lower water pipe 2 and returns to the heat storage water tank 1 from the upper water pipe 3, the water tank is repeatedly circulated to realize independent heat storage of the water tank until the water temperature reaches the set value, the controller 11 receives a water tank temperature sensor T1 signal and sends closing instructions to each valve and the circulating pump, and heat storage of the system is stopped.

And then the system enters a heat preservation stage, no liquid water exists in gravel gaps, the convection heat transfer on the surface of the water tank is greatly reduced, and the core energy of the heat storage water tank is ensured.

A heat taking mode: when the hot user has a useful heat demand, the system enters a heat-removal mode. In the mode, firstly, the stored heat energy in the water tank is utilized, and the path of circulating water flowing through the equipment is as follows: 3 → V4 → P2 → V9 → 10 → V10 → V5 → 2 → 3. The specific implementation mode is as follows: the controller 11 firstly sends an opening instruction to the second circulating pump P2, the fourth valve V4, the fifth valve V5, the ninth valve V9 and the tenth valve V10, water in the heat storage water tank 1 is pumped out by the upper water pipe 3, enters the heat taking heat exchanger 10 through the fourth valve V4, the second circulating pump P2 and the ninth valve V9 to complete heat release, then passes through the tenth valve V10 and the fifth valve V5 and returns to the heat storage water tank 1 through the lower water pipe 2, and the circulation is repeated, so that heat energy in the water tank is continuously released to a heat user.

When the water outlet temperature of the heat storage water tank does not meet the heat taking requirement of a heat user, the stored heat energy of the gravel layer can be extracted again. If the temperature of the heat storage and water outlet temperature sensor T7 is lower than a heat taking set value, the controller 11 is connected with a T7 signal, the temperature value of the gravel temperature sensor T2 is read, if T2 is not more than T7, the controller 11 closes all circulating pumps and valves, and the system stops a heat taking mode; if T2 > T7, the system extracts heat from the heat-storage gravel, and the path of circulating water flowing through the equipment is as follows: 6 → V2 → P2 → V9 → 10 → V6 → V3 → 3 → 2 → P1 → V1 → 5 → 4 → 6. The specific implementation mode is as follows: the controller 11 sends a closing instruction to the fifth valve V5, sends an opening instruction to the first circulating pump P1 and the first valve V1, at this time, the lower water pipe 2 pumps water from the hot water storage tank 1, passes through the first circulating pump P1, joins the incoming flow passing through the tenth valve V10, enters the water injection well 5 through the first valve V1, the circulating water passes through the heat storage gravel 4 to absorb heat, collects the heat to the water pumping well 6 to increase the water level thereof, when the water level reaches a set position, the controller 11 receives a signal of a gravel level sensor T6, sends a closing instruction to the fourth valve V4 and the tenth valve V10, and sends an opening instruction to the second valve V2, the third valve V3 and the sixth valve V6, at this time, the water in the water pumping well 6 is sucked into the second circulating pump P2, and sent to the heat extraction heat exchanger 10 to release heat, and then enters the hot water storage tank 1 through the sixth valve V6, the third valve V3 and the upper water pipe 3, circulating water in the water tank is sucked into a first circulating pump P1 through a lower water pipe 2, enters a water injection well 5 through a first valve V1, enters heat storage gravel 4 again, absorbs heat, returns to a water pumping well 6, circulates repeatedly, and continuously releases heat energy in the gravel layer to a heat user. And when the temperature of the heat storage and water outlet temperature sensor T7 is lower than the heat taking set value, the controller 11 closes all circulating pumps and valves, and the system stops the heat taking mode.

The water replenishing function: for the heat storage system in service for a long time, the water-proof heat-insulating layer 7 cannot avoid the problems of damage, aging, cracking and the like, water flowing in the gravel layer can leak and evaporate to a certain extent and then flows away, and when the water level in the water tank is lower than a set value, the water replenishing function needs to be started by the system. This function is with the water introduction system at water source, and the moisturizing is flowed through equipment route and is: water source → P3 → V11 → V7 → 9 → V3 → 3 → 1. The specific implementation mode is as follows: in the heat storage (or heat preservation) mode, when the water level in the hot water storage tank 1 is lower than the set lower limit value (or the standard set value), the controller 11 receives a signal from a tank lower limit level sensor T4 (a tank set level sensor T3), sends an opening instruction to the eleventh valve V11 and the third circulating pump P3, water flows through the eleventh valve V11 from the third circulating pump P3, then flows through the seventh valve V7, the heat source 9 and the third valve V3, and finally flows into the hot water storage tank 1 through the upper water pipe 3, so as to realize system water replenishment until the water level in the hot water storage tank 1 is higher than the set lower limit value (or the standard set value), and the controller 11 sends a closing instruction to the eleventh valve V11 and the third circulating pump P3, so as to stop the water replenishment.

The pressure relief function: in the heat storage or heat preservation mode, if the pressure in the heat storage water tank 1 exceeds the limit value, the controller 11 receives a signal from a water tank pressure sensor T5, sends an opening command to the twelfth valve V12, discharges steam to reduce the pressure in the heat storage water tank 1, and when the pressure is lower than the limit value, the controller 11 sends a closing command to the twelfth valve V12, and ends the pressure relief function.

Claims

1. The seasonal underground solid-liquid combined heat storage method capable of reducing heat loss is characterized in that a heat storage water tank (1) and heat storage gravels (4) are used as a heat storage body, the water tank is arranged in a gravel layer, the pore volume of the heat storage gravels (4) is controlled to be smaller than 1/2 of the volume of the heat storage water tank (1), the heat storage water tank and the heat storage gravels are used in series in the heat storage stage, circulating water sequentially flows through the water tank and the gravels under the action of a first circulating pump (P1) and a second circulating pump (P2), and the temperature difference between an inlet heat source and an outlet heat source is increased, so that the heat storage efficiency is improved.

2. The cross-season underground solid-liquid combined heat storage method capable of reducing heat loss is characterized in that solid-liquid separation operation is carried out on heat storage gravels (4) in a heat preservation stage, gravel pore water completely enters a heat storage water tank (1) under the action of a second circulating pump (P2), then the cooperation of a liquid level sensor (T3) and a controller (11) is set by the water tank, water is supplemented to the heat storage water tank (1), then the water tank temperature sensor (T1) is matched with the controller (11), independent heat storage is carried out on the heat storage water tank (1), solid-liquid heat separation storage is finally achieved, and heat loss is reduced.

3. The seasonal underground solid-liquid combined heat storage method for reducing heat loss is characterized in that in a heat taking stage, a heat storage water tank (1) is used for releasing heat of a heat taking heat exchanger (10), and when the temperature of the water tank is lower than a heat taking set value, a gravel temperature sensor (T2), a heat storage water outlet temperature sensor (T7) and a controller (11) are matched to achieve heat taking circulation by using heat storage gravel (4).