Atmospheric hot water boiler---boiler room system setup

Atmospheric hot water boiler---boiler room system setup

1. Setting of mechanical circulating heating system

Compared with the pressurized boiler system, there are many differences in the connection mode of equipment and pipes in the heating system of atmospheric hot water boiler. The remarkable difference is that the hot water circulating pump of the atmospheric boiler is located on the outlet side of the boiler, that is, the outlet of the atmospheric boiler is connected with the inlet of the circulating pump, and the circulating hot water is pumped out from the boiler. After being pressurized by the hot water pump, it is sent to the heat user through the pipe network. When the circulating hot water returns to the boiler room, it should first go through the detergent, the resistance regulating valve and the opening and closing valve, and then return to the atmospheric hot water boiler. Among them, the detergent is the same as the pressure-bearing system, and the latter two valves are unique to the mechanical circulation heating system of atmospheric boiler. Among them, the resistance regulating valve can use globe valve, gate valve and so on, which can make the pressurized water in the circulation pipeline decompress the backwater when it returns to the boiler under atmospheric pressure. at the same time, it has the function of regulating the continuous change of working conditions in the operating system. The function of the opening and closing valve is to cut off the pipeline in time when the circulating pump stops running suddenly so as to prevent a series of accidents such as the possible emptying of the circulating pipeline.

2.Setting of boiler expansion water tank

The setting of the boiler expansion tank is almost essential for the atmospheric boiler, which can not only absorb the thermal expansion caused by the heating of the boiler water, but also increase the water volume of the boiler to prevent it from being emptied by the pump, and can also accommodate once the pump is stopped, the opening and closing valve is lagging behind or the circulating hot water flowing back due to lax closure. For the atmospheric hot water boiler with large drum volume, part of the space can be reserved in the upper part of the drum, and this space must communicate with the atmosphere. For ordinary boilers, it is necessary to set up another boiler expansion water tank which is connected with the atmosphere. The expansion tank of the boiler is generally located at the top of the boiler, the height of the tank is usually about 1 meter, and the volume is generally not more thanThe following problems should be paid attention to in setting up the boiler expansion water tank:

The expansion space of ① water tank should be larger than the net increment of water expansion of the system.

The expansion space of the ② water tank must have an air vent communicating with the atmosphere, and the diameter of the vent is not less than 100mm, so as to ensure the operation of the boiler under atmospheric pressure.

3. Setting of atmospheric connection tube

In order to prevent the pressure-bearing use of the atmospheric hot water boiler, the installation of the system should ensure that the gauge pressure at the top of the boiler body is zero in any case. Therefore, the atmospheric connecting tube directly to the atmosphere should be arranged at the top of the atmospheric boiler body, and the atmospheric connecting tube should be guaranteed to be smooth, and no water seal should be set. The atmospheric connecting tube of the boiler shall be connected to a safe place, generally to the top of the boiler expansion water tank, the connecting tube shall not be reduced, the height shall not exceed 2m, no valves shall be installed on it, and there shall be anti-freezing measures.

4. Setting of automatic opening and closing Valve

Because the atmospheric pressure hot water boiler is equivalent to an open heating water tank, and the circulating water of the system is sent to the higher heat users before the pressure head of the circulating water pump. When the pump stops normally or suddenly for some reason, the pump pressure head disappears, and the circulating water higher than the boiler water level will be poured into the boiler or even spilled by the boiler expansion water tank due to the action of the gravity pressure head.3 B) U% u' Z2 G. v0 e

In order to avoid the above phenomenon, an automatic opening and closing valve should be installed at the return port of the boiler. when the circulating water pump is running, the opening and closing valve opens itself, the boiler is connected with the system, and the water of the system circulates. Once the pump is stopped, the opening and closing valve immediately closes by itself, which separates the boiler from the system and avoids the overflow of system water into the boiler.* Z% J7

5. Setting of circulating water pump

1) in the heating system of atmospheric pressure hot water boiler, the circulating water pump is set behind the boiler, and the hot water in the boiler is extracted and sent to the heat user through the pipe network, so the temperature of the water flowing through the circulating water pump is higher, so it is best to use the hot water pump.

2) in the heating system of atmospheric hot water boiler, the function of circulating water pump is to pump the hot water from the boiler to heat users of any height, and to promote the continuous circulation of hot water to overcome the resistance of the system. The higher the building is, the higher the lifting height is, the greater the lift of the pump is. The system resistance of the pipeline plus the gravity head of the water between the boiler water level and the highest point of the system and the additional head margin are the head of the hot water circulating pump.  D% a; v: d* s. T1 N

3) the method of determining the necessary flow rate of hot water circulating pump is the same as that of pressurized boiler system.

4) because the circulating water pump is located at the outlet end of the boiler, and the suction end of the pump is negative pressure, the outlet temperature of the boiler is higher, so it is easy to vaporize in the pump, resulting in cavitation, affecting the normal operation of the pump. In order to prevent the possibility of cavitation of the water pump, there should be a certain height difference between the liquid surface of the boiler expansion tank and the axis of the pump. When the static pressure formed between the inlet of the circulating pump and the liquid surface of the boiler expansion tank is greater than the sum of the flow resistance of the pipe at the inlet of the circulating pump, it is not necessary to consider the possibility of cavitation of the circulating water pump. When the circulating water pump is installed, the distance between the inlet center line and the lowest water level of the boiler should not be less than 2 meters.

5) the number of hot water circulating pumps should not be less than 2, one in operation and one in standby.