The project site is located on the west side of Taiping Village, Nankou Town, Changping District, Beijing. The campus covers an area of about 80 hectares, with a total construction area of about 18× 104m2. The scheme design began in August of 20001year, and the construction drawing design was approved by the Municipal Planning Commission. In September 2003, the new school year was put into use.
The campus plane is divided into four areas: front area, middle area, back area and mountainous area. The front area is the teaching area, including the administrative teaching and research building, the library, the teaching laboratory building and the lecture hall. The central area is the dormitory area, including students' dormitory and canteen, police officers' dormitory and canteen and teachers' dormitory. The back area is the venue area, including the police skill hall, physical fitness hall, swimming pool, auditorium, standard sports ground and cadre training building. The mountainous area is a foreign research area, including a foreign research building, a property building and a sunken shooting range.
There are more than 20 buildings on campus, all of which are multi-storey buildings. 5 floors of administrative teaching and research building, underground 1 floor; The auditorium is 3rd floor, underground 1 floor; The rest are 2-4 floors. The external wall is made of 300-thick aerated concrete blocks with a heat transfer coefficient of 0.82 W/(m2 k). The roof insulation material is 60 thick polystyrene board or metal insulation board, and the heat transfer coefficient is 0.6 ~ 0.78 w/(m2 k). The heat transfer coefficient of aluminum alloy double glazing is 3.5 W/(m2 k).
2. Generation of groundwater heat pump system scheme
To establish a modern institution of higher learning and create a good teaching and living environment for students and staff, it is required to set up central air conditioning in the whole hospital, which is warm in winter and cool in summer.
Heating and supplying domestic hot water are the primary problems in schools, which are more important than refrigeration. There must be a reliable heating scheme. What kind of energy should be used for cooling and heating must be decided according to the external conditions of the region. The commonly used schemes are: ① urban heating network heating+electric refrigeration; (2) Coal-fired boiler heating+electric refrigeration; (3) gas boiler heating+electric refrigeration; (4) Oil-fired boiler heating+electric refrigeration; ⑤ Electric boiler heating+electric refrigeration.
The new school is located in the suburb of Changping, adjacent to the Ming Tombs in the south, and is a key area of environmental protection in Beijing. There is no urban heating network supply in this area, so scheme ① cannot be adopted; Scheme (2) is a coal-fired boiler, which does not meet the requirements of environmental protection and is explicitly prohibited by the Beijing Municipal Government; Fuel oil is expensive and the operation cost is high. Generally, there are only a few days of oil reserves at most, so it is very troublesome and inconvenient to set up a special transportation fleet to organize oil transportation. Therefore, scheme ④ is not suitable; Electric energy is a clean and high-grade energy source. In China, 70% of electricity is thermoelectric, which is converted from coal, and its conversion rate is only about 30%. It is uneconomical to convert high-grade electric energy into low-grade heat energy for heating. The campus is large, so it is obviously unreasonable to use electric boilers for heating in winter. Scheme ⑤ should not be adopted. Schemes ①, ②, ④ and ⑤ are not applicable to this project.
Scheme ③ is gas-fired boiler heating. It is known that the natural gas pipeline in Changping District is 5 ~ 10 km away from the campus, and it is uncertain whether it can be connected in the past two years.
In order to implement the requirements of Beijing Municipal Government for air pollution control, Party A entrusted Beijing Geological Engineering Survey Institute to conduct a preliminary survey of the geological and hydrogeological conditions in this area, and confirmed that the geological and hydrogeological conditions in this area can fully meet the design requirements of the groundwater heat pump system.
Party A requires that two schemes of gas boiler heating+electric refrigeration (scheme 1) and groundwater heat pump (hereinafter referred to as heat pump, scheme 2) be compared and selected according to the site resources.
Total investment:
Scheme1:59.292 million yuan (excluding investment in natural gas pipeline from Changping to campus).
Scheme 2: 544 1.5 million yuan.
Operating cost comparison
(Based on the electricity and gas charges in 2003, the electricity charge is 0.57 yuan /kW, and the natural gas 1.8 yuan/nm3);
Scheme 1: Summer 1 1.2 yuan/m2.
27.9 yuan/square meter in winter
Scheme 2: Summer 10.2 yuan/m2.
25.4 yuan/square meter in winter
Features of the plan:
Scheme 1:
① One-time investment and annual operating expenses are slightly higher than those in Scheme 2;
(2) to build a boiler room on campus, the general layout is difficult to plan;
③ The problem of natural gas export pipeline is difficult to solve, which will affect the time of putting into use.
Option 2:
① A heat pump system can provide heating in winter and cooling in summer without building a boiler room;
(2) No boiler chimneys, cooling towers and other equipment, no heat, humidity, dust and chemicals discharged into the atmosphere, no air pollution and noise pollution;
(3) saving room area;
(4) When sanitary hot water is provided in summer, cold recovery can be carried out, and the cold water after heat extraction can be used for air conditioning.
3. Introduction of groundwater heat pump system
Design total cooling load of air conditioner:15153 kw; Total heat load: 1608 1kW. The peak water demand is 900m3/h, and the operation effect is good since it was put into use in 2003.
4. Regional hydrogeological conditions
The strata with water supply significance in this area are mainly Gaoyuzhuang Formation (Chg) of Great Wall System and Wumishan Formation (JxW) of Jixian System.
The strata of Gaoyuzhuang Formation of Great Wall System
This formation is distributed in the northern mountainous area of Taipingzhuang and near the piedmont. The lithology is light gray thick siliceous dolomite, siliceous limestone and flint dolomite. Rock is weathered and broken, and cracks develop.
The strata of Wumishan Formation in Jixian System
This formation is mainly distributed in the piedmont of Taipingzhuang to the plain, concealed under the loose accumulation of Quaternary alluvial deposits in the piedmont. The lithology is mainly grayish white dolomite, dolomitic limestone, dolomitic limestone containing flint blocks and crystalline dolomite. Rock is weathered and fractured, and karst fractures are developed, especially near the fault structure zone, which shows that groundwater is rich in conditions and is the target rock stratum of ideal water supply source.
The groundwater in this area is replenished not only by a small amount of atmospheric precipitation infiltration through loose Quaternary strata, but also by the atmospheric precipitation infiltration from the Ming Tombs area through the northern exposed bedrock mountain area and the lateral recharge of groundwater from this stratum through plane cracks and structural cracks.
According to the analysis of exploration data, the stratum of Wumishan Formation (JxW) in Jixian County is concealed under the loose deposits of Quaternary, and the rock fracture structure, karst fracture, water permeability and water conductivity are well developed, so it is a good water supply source.
5. Well water system
* * * Drilling 12 wells (6 pumping and 6 irrigation), with a well depth of about 350m, a well spacing of 150 ~ 200m, a buried depth of about 80m, and a single well water output of150m3/h. After extracting energy, all the extracted groundwater is reinjected to the ground;
The campus is divided into two groundwater heat pump systems. The upstream of the water source in this area is northeast, and six wells are arranged along the west and south boundaries of the campus. The southwest direction is the downstream direction of groundwater in this area, and the well spacing is 200 ~ 300 m. Six recharge wells are arranged in a large area in the middle of the campus to recharge backwater upstream to ensure the sufficiency and stability of water sources. Because there is room for the lifting height of well water, the number of heat pump units is controlled with the change of load, so the water volume of the system changes. In order to save water and energy, all submersible pumps adopt variable frequency pumps.
The underground water supply pump section has a diameter of 400mm and a depth of 350m, and the designed water output of each well is150m3/h/h.
6. Selection of air conditioning equipment
The whole school has designed two sets of groundwater heat pump systems, and the heat pump system room of the administration building is located in the basement of the administration building. There are 22 heat pump units in the computer room. The heat pump system room in the audience hall is located in the basement of the audience hall.
The building area of the front area (teaching administrative area) and the central area (dormitory area) is1.6×104m2, the cooling load of air conditioning is 10459kW, the heating load is 93 14kW, and the heating load of sanitary hot water is/kloc-0. LSB of semi-closed screw underground water source heat pump is selected. The back area (venue area) has a building area of 4.9× 104m2, with air conditioning cooling load of 5556kW, heating load of 5834kW and sanitary hot water heating load of 1000kW. LSBLGR-530 14 units are selected, of which two units supply sanitary hot water all year round, and the terminal form adopts all-air air conditioning unit+fan coil unit+fresh air.
7. Automatic control and adjustment
Automatic control of heat pump unit;
Each heat pump unit is equipped with a microcomputer control device, and the terminal device of the air conditioning system adopts a two-way control valve to automatically (or manually) control the number of heat pump units and circulating pumps according to the return water temperature of cold and hot water of the air conditioner, so that the running time of each unit is equal; The heat pump unit is interlocked with the cold and hot water pump and the deep well pump. The starting sequence is deep well pump-cold and hot water pump-heat pump unit, and the stopping sequence is deep well pump-cold and hot water pump-heat pump unit. Considering that there are many heat pump units, pumps are not in one-to-one correspondence, and 5 ~ 6 heat pump units are one pump, therefore, the inlet and outlet pipelines of heat pump units are manually switched by manual butterfly, which can not only meet the use requirements, but also save investment.
Well group control:
Control requirements: ① 1 water supply well 150m3/h, which can supply 5 heat pump units. When the number of heat pump units is less than 5, any one 1 submersible pump can meet the requirements of well water quantity of heat pump units. The variable frequency operation of submersible pump can meet the flow and pressure requirements of heat pump unit and save water and electricity to the maximum extent. ② When the number of heat pump units increases, 1 submersible pump will be put into operation. 1 pump is used for constant flow operation, and 1 variable frequency pump is used for insufficient flow. ③ Submersible pump is loaded in the above manner. ④ On the contrary, the number of submersible pumps decreases one by one.
Control system:
① The control mode of submersible pump system is similar to that of tap water constant pressure water supply system, which ensures the constant water supply pressure of the user's pipe network. According to the set pipe network pressure and the actual pipe network pressure signal measured by the pressure sensor, the control system adopts the operation mode of 1 speed regulating pump with four constant-speed pumps to automatically start the number of constant-speed pumps and the speed of speed regulating pumps, so as to ensure the water supply pressure when the water volume changes and save electricity to the maximum extent; (2) In order to prevent the water pump from rusting after long-term non-operation, PLC controls the water pump to operate as a variable frequency pump regularly, that is, the function of automatically changing the pump; (3) Intuitive graphic display and inspection function, which graphically displays pipeline pressure, submersible pump operation status, water quantity and total water quantity of each well, equipment status and system working status; ④ Alarm and protection function: When the pressure and flow of the water main reach the alarm state and the starting cabinet fails, the operation panel will give an audible and visual alarm. ⑤ Detect and record the water quantity and running status of each submersible pump.
Operation regulation of air conditioning circulating water system
Air-conditioning circulating water pump adopts constant speed pump, and there is a pressure difference bypass valve between air-conditioning distribution headers, so the air-conditioning circulating water system is a typical constant flow water system.
8. Operation effect of groundwater heat pump
The ground source heat pump heating system was put into operation in June 2003 +065438+ 10, and the operation effect has been good. According to the records and display data of winter and summer operating conditions, the indoor temperature of users is stable, which can meet the needs of users for cold, heat load, domestic hot water and so on.
In summer, the electricity consumption of air conditioning and domestic hot water system is about 6364kW；; The electricity consumption of heating and domestic hot water system in winter is about 4660kW.
In summer, refrigeration began gradually from mid-May to the end of September of that year, and the refrigeration cost was about 1.53 million yuan.
In winter, from 1 1 to the end of March of the following year, the heating cost is about 3.809 million yuan;
The comprehensive unit price is about 20 yuan for heating per square meter in winter and 8 yuan for cooling per square meter in summer.
9. Operation of water wells
It can meet the requirements of pumping irrigation, the peak water demand is 900m3/h, and the water intake can be recharged 100%. After four years of operation, the water level has no obvious downward trend, the water quality has not changed, and the water quantity can meet the water demand of the unit.
65438+
Because the whole system adopts frequency conversion speed regulation technology, according to the requirements of flow and pressure of heat pump unit, submersible pump runs in frequency conversion to save water and electricity to the maximum extent, so the economic benefit of the whole system is very remarkable, and it also brings great social and environmental benefits. The visiting groups are in an endless stream, and the construction unit is very satisfied.
1 1. Project summary
(1) Replacing boiler room and freezing station with heat pump unit can reduce chimneys and cooling towers, greatly reduce the degree of air pollution, improve urban environmental sanitation, and be beneficial to ecological balance. It is especially suitable for using heat pumps in areas where boiler rooms are restricted, such as key cultural relics protection areas, commercial centers, tourist areas, convalescent areas, etc.
(2) The key of groundwater heat pump system is water source. First, with the approval of local administrative, environmental protection, water conservancy and other competent departments, carry out hydrogeological investigation, obtain geological investigation report and groundwater resources evaluation report, including parameters such as water quantity, water temperature, water level and water quality, and design drilling position. Make a recharge plan according to local conditions to ensure that all water is recharged and water resources are not polluted.
(3) The working principle of heat pump unit is to use well water as cooling water in summer and well water as heat source in winter. After the pipes of air conditioning cold and hot water system and well water system are configured, the switching valve is used to switch between winter and summer working conditions, as shown in Figure 3-3. Therefore, the tightness of valve 1 ~ 8 is very important. If the valve leaks, two systems will be connected in series. This project has such a problem. The valves 6 and 7 are leaking, and the water from the air conditioning circulating water system leaks into the recharge well, so the pressure of the air conditioning water system can't go up, and the system can't operate normally.
(4) The dynamic water level of well water and the size of well water pipe network have great influence on the energy consumption of the system. The deeper the dynamic water level, the greater the power consumption. The author calculates that the electricity consumption of deep well pumps in this project accounts for about 15% ~ 18% of the total electricity consumption. If the dynamic water level is increased by half, the lifting height of the pump will be reduced by half. When the action radius of the system decreases, the resistance of the pipe network decreases. When the sum of the two items is reduced by 1/2, the lift of the pump is reduced by half, that is, the power consumption is reduced by about 1/2, which can save electricity by about 8% ~ 10%.
Groundwater heat pump technology has a history of several decades in North America and Europe, and it is a widely used and mature heating and air conditioning technology. Groundwater heat pump heating and air conditioning system has been applied in China for more than ten years, and its development is relatively slow compared with foreign countries. Beijing police college groundwater heat pump system is an application example of water-water heat pump system in engineering, which has reference value for the popularization of this technology in the future. I also hope to accumulate experience in future operations, improve management level, provide quality services for owners and save operating costs. It is expected that the use of this system can achieve a win-win situation of social benefits, environmental benefits and economic benefits.