Requirements: ice storage construction organization design. Urgent! !

Design and construction method of ice storage system

I. Overview of the Project

Beijing International Finance Center is located in the east of Yuetan North Bridge, and the construction unit is Jin Rong Real Estate Development Co., Ltd., the capital group. The building functions are office, hotel and bank complex buildings with a total construction area of 1 16000 square meters. This is the largest ice storage project in China. The project was constructed and installed by the first project department of Beijing Construction Engineering General Mechanical and Electrical Equipment Installation Engineering Co., Ltd. The system mainly provides air conditioning chilled water for the building, and the freezing station is located on the third floor underground. The building area of the computer room is 1200m2 (the ice storage tank is 520m2). The ice storage air conditioning system is adopted in the freezing station, which makes full use of the cheap low-voltage electricity at night to store the cold energy, supplement the air conditioning cooling load during the peak electricity consumption period, and save the system operation cost.

Second, the equipment configuration

(1) cold source

1. Three double-working screw chillers (YSFAFAS55CNES) and two in York (joint venture). Two centrifugal chillers with basic load (ykfebh 55 CPE)York (joint venture).

(2) Cooling tower: Dalian speed

There are 5 cooling towers, 2 CTA-600 ufw and 3 CTA-450 ufw.

(3) Plate heat exchangers: There are three APV plate heat exchangers in Denmark, and the APV plate heat exchanger J185-MGS16/16 is selected.

(4) Ice storage tank (field processing)

There are six ice storage tanks * * *, and the maximum ice storage capacity is 3 1787.2KW(9040RT). (See table 1)

(5) Ethylene glycol circulating water pump: KSB, Germany.

There are 4 glycol circulating pumps, including 1 standby pump and 4 frequency converters.

(6) Cooling water circulating pump: Germany KSB

Four horizontal centrifugal pumps are selected as cooling water circulating pumps, of which 1 is standby.

Third, the operation strategy:

(a) load description

According to the usage of the building and the preliminary design estimation results, the peak cooling load of the whole building is 1 1428KW(3250RT). Due to the change of temperature, the daily load of air conditioning system will change during the whole operation period. According to the load distribution, the hourly air conditioning load of 100% is calculated (see Table 2).

The ice storage mode can be a complete (total) ice storage mode or a partial (partial) ice storage mode. This project adopts partial ice storage method.

According to the daily design load 100% provided by HVAC specialty, the maximum hourly cooling load is 1 1428KW(3250RT).

Design daily cooling load:151705kwh (43144th).

Maximum hourly cooling load: 2286KW(650RT)

Maximum hourly cooling load after deducting basic load: 9 142.33KW(2600RT).

Cooling load after deducting the cooling load of basic load on design day: 852.4 kWh (27 27,544 rth).

(2) Brief introduction of system flow

In this design, the ice storage equipment is ice hockey ice storage equipment, and the system adopts series single circulation loop. In the circulation loop, the ethylene glycol refrigeration main engine is placed upstream of the ice storage device. There are three plate heat exchangers in the system, each with a heat exchange capacity of 3961kw (1126 rt), which are used to isolate the glycol loop of the ice storage system from the water loop leading to the air conditioning load, so as to ensure that glycol only flows in the ice storage cycle and does not flow through the air conditioning load loop, thereby reducing the amount of glycol and avoiding the leakage of glycol in the air conditioning load loop. There are four electric control valves CV 1, CV2 and cv8cv9 in the glycol circuit. According to the change of cooling load, the flow rate of ethylene glycol entering the ice storage device is adjusted by electric regulating valves cv 1 and cv2 to ensure the constant temperature of ethylene glycol entering the plate heat exchanger and meet the requirements of cooling load. Electric regulating valve CV8. CV9 regulates the ethylene glycol flow into the plate heat exchanger to ensure that the water side temperature entering the plate heat exchanger is constant and meet the cooling load requirements. At the same time, the chilled water loop of the air conditioner adopts a two-stage pump system, which saves operating costs.

The maximum ice storage capacity of this project is 3 1, 787.2 kW(9040 rt), which is divided into six ice tanks with a clear height of 2.35 meters. In order to reduce the occupied area of the ice storage tank as much as possible, we make the ice storage tank non-standard, make full use of the building space, and reserve the equipment entrance and inspection hole above the roof for equipment and maintenance personnel to enter and exit. The structure of the ice tank is external insulation. The structure from the ice storage tank to the outside is divided into waterproof coating and rubber-plastic cold insulation layer. In order to meet the demand of peak load cutting and valley filling in the power sector, the power peak section, dual-mode water chillers and base-load water chillers operate at full load, and the insufficient cooling capacity is supplied by deicing output. Standby is also considered in the system design. When any unit fails, the standby basic load chiller will be started to meet the needs of air conditioning and refrigeration. When any double-condition water chiller fails, start the standby base-load water chiller to meet the air conditioning and refrigeration requirements for the next day, and when the ice storage tank in any partition fails, start the standby base-load water chiller to meet the air conditioning and refrigeration requirements.

In the transitional season, when the air conditioner is cooling, the water chiller stops and only outputs deicing refrigeration, which can meet the air conditioning demand. At this time, the electric regulating valve CV 1, the electric valve CV3 is closed, and the electric valves CV2 and CV4 are opened, so that the ethylene glycol solution ice does not flow through the dual-mode water chiller, and the waste of pump power is avoided. When the cold storage tank is used for cooling alone, the glycol solution pump adopts frequency conversion technology, which greatly reduces the energy consumption of the pump.

(3) Ice storage operation strategy

According to the all-day cooling load curve and the time-of-use electricity price in Beijing, this design adopts the partial ice storage strategy with balanced load, so that the cold storage at night can meet the needs of air conditioning cooling load during peak electricity consumption periods to the greatest extent, save the system operation cost and occupy the effective area of the building as little as possible.

Fourth, the operation comparison:

Due to the implementation of peak-valley electricity price policy in Beijing Power Grid, the peak-valley electricity price has reached 4.3∶ 1. Therefore, using ice storage system can greatly reduce the operating cost of air conditioning system. At this stage, the peak-valley time-of-use electricity price is as follows:

Control of ethylene glycol system According to the peak-valley period of power load (the level of electricity price) and the requirements of air conditioning load, the whole ice storage refrigeration system can automatically switch the operating conditions of the system:

(1) Ice-making mode of dual-mode main engine

(2) Double-working-mode host+ice-melting refrigeration mode (full load)

(3) Single melting ice refrigeration mode (partial load). According to the requirements of working conditions, the control system automatically opens and closes the electric valve to form a fluid channel required for a certain working condition. The ice melting speed is controlled by valve adjustment; In the case of single ice melting and cooling, the ice melting speed and water supply temperature are controlled by frequency conversion of glycol pump and adjusting the number of units.

1. Ice making mode of dual-mode host: 23: 00 ~ 7: 00.

During this period, the electricity is low and the electricity price is low. The dual-mode host is set to ice-making mode, running at full load, and all the generated cold energy is stored in the form of ice for use at the peak of cooling load. Start the dual-mode host and glycol pump to form an ice-making cycle among the dual-mode host, glycol pump and ice storage tank. In the low-power period, the low-cost power in the low-power period is fully utilized, and the three dual-mode hosts fully make ice. Firstly, the sensible heat in the cooling circuit of the refrigeration unit is cooled until the phase transition temperature of the cold storage ball is reached. After reaching the phase change temperature, the cold storage ball begins to change phase (freeze) with the absorption of the cold generated by the unit. In ice period, the ice hockey continuously absorbs the cold generated by the unit, and the temperature of the frozen liquid generated by the refrigeration unit also drops slightly to the corresponding final temperature at the end of the phase change, which indicates that the rapid cooling speed in the cold storage stage is very fast, because the efficiency of the main engine is set by the outdoor air parameter system when making ice, and the time required to reach the designed ice storage capacity may be longer or shorter than that in the low power stage. If it exceeds the low power consumption period, the system will make ice in the early peak period or even the peak period, and the system operating cost will increase. If it is shorter than the power trough period, it will lead to ineffective or inefficient operation of the system after reaching the designed ice storage capacity (the outlet temperature of the main engine is very low), and the operating cost of the system will also increase. Therefore, it is necessary to make full use of the ice-making capacity of the refrigeration unit and the ice storage capacity of the ice hockey in the low-power period to maximize the ice storage effect (that is, the most effective effect). The conditions for judging the end of ice making are: