Treatment of air blockage in heating system

Treatment of air blockage in heating system

1. Reduce the water supply of the system.

Strengthen the management of heating pipe network to reduce the phenomenon of running, running, dripping and leakage. For the intermittent heating system, when the heat source is heated, the water temperature of the heating system increases gradually, and with the air spilling into the system, the water supply temperature of the intermittent heating system fluctuates greatly, generally reaching a temperature difference of 40 ℃ and 50 mol. For a closed system with a water capacity of more than 100 cubic meters, the volume changes due to the temperature change, which will cause great pressure changes, if the maximum pressure point of the system is exceeded. The excess water is discharged by the pressure relief drainage equipment or valve to reach the allowable pressure value, otherwise it is lower than the minimum of the constant pressure point of the system, the water replenishment equipment is started to reach the allowable pressure value. Most of our common constant pressure equipment are expansion water tank, air pressure tank and frequency conversion pump, the expansion water tank has expansion tube, the system is not closed, and the pressure change is relatively small; if the pressure tank is fixed, if you choose it improperly, or the expansion film in disrepair breaks, it will cause sharp fluctuations in the system pressure, so that a large number of water replenishment and discharge phenomena occur in the system, and the gas will enter the system. Frequency conversion pump constant pressure, the whole system is steel, it is the most sensitive to the pressure change caused by water expansion, there is often the occurrence of water replenishment and discharge. If the system is large, it is recommended to use low temperature and long supply, or reform the system to reduce the occurrence of water replenishment and discharge, such as changing the way of constant pressure.

2. Put an end to the negative pressure of the system.

In the aspect of constant pressure, the first is to select the correct constant pressure to prevent the emptying phenomenon, and the second is to select the correct constant pressure point to prevent the negative pressure during operation. Due to the negative pressure caused by the mismatch between the system and equipment, it is possible to temporarily increase the inlet pressure of the circulating water pump, generally increasing the constant pressure. For example, in a central heating system of a gas-fired boiler, the highest building is a six-story residential building, the constant pressure point of the system is the entrance of circulating water pump, the constant pressure mode is frequency conversion water supply and constant pressure, and the constant pressure point pressure is 21mH2O, this phenomenon occurs in operation, the heating in the duty room and other ancillary rooms of the boiler room is always not hot, and the radiator exhaust valve is opened, and the gas is discharged every half hour, otherwise it is not hot. After inspection, it is found that the inlet pressure gauge of the circulating water pump is negative, which indicates that it is in a vacuum state, which is mainly due to the excessive selection of the circulating water pump and the increase of the constant pressure point pressure to 26mH2O, and the pressure of the pressure gauge is positive. Under this constant pressure point, the radiator does not have the phenomenon of gas storage and non-heat. To solve this problem, increasing the pressure at the constant pressure point is not an ideal solution. If you replace a pump that matches the heating system, not only the negative pressure problem can be solved fundamentally, but also the power of the newly replaced pump is much less than that of the existing pump, which can often save half of the electricity, that is to say, the existing pump consumes twice as much electricity, which can recoup the initial investment in some boiler rooms in a few years. It not only saves the operating cost for the users, but also saves the energy for the society, which is a win-win good thing.

In addition, if a system has two constant pressure points, there will also be emptying phenomenon, which makes the gas enter the system. For example, the original two heating systems use two expansion tanks for constant pressure respectively, and after the two systems are merged into one system, the redundant expansion tanks are not removed, resulting in the coexistence of two expansion tanks in a heating system. the result is that the real constant pressure point of the system is between the two expansion tanks, the expansion tank at the upstream end overflows, and the expansion tank at the downstream end is often emptied, resulting in negative pressure in the system. Air enters the system. During the operation of the heating system, many radiators are not hot, and the phenomenon of accumulated gas is obviously improved after the shutdown of the circulating water pump, but the phenomenon of accumulated gas remains the same when the circulating water pump starts again. Now the original expansion water tank is removed, and the air blockage phenomenon has not occurred again.

3. Eliminate serious hydraulic maladjustment.

The inconsistency between the actual flow and the design flow of thermal users in the system is called the hydraulic maladjustment, which is generally measured by hydraulic misdispatching. A certain hydraulic imbalance is allowed in the design of the heating system, as long as it is within the prescribed range. For example, the operation of the pipe network is not well adjusted, and the load change of the heat users will cause hydraulic maladjustment, which will make the water flow rate of some heat users on the low side and the flow rate on the low side, thus causing the heating equipment of the hydraulic maladjustment users to become a place where gas accumulates and leads to lack of heat.

4. Strengthen the maintenance of heating system in non-heating season.

In the non-heating season, the maintenance of the heating system is very important, which is the basic requirement to reduce water replenishment, safe operation and ensure comfortable heating. At the end of each heating season, the pipe network is repaired, the valve packing and regulating parts are maintained, and the exhaust equipment is repaired in time to confirm whether it is reliable and effective.