Fixed Pressure Mode in Heating System of Biomass Boiler

Fixed pressure mode in biomass boiler heating system: In high temperature hot water supply system, because the water temperature is higher than the saturation temperature of water under normal pressure, the pressure in the system should be higher than the saturation pressure of the corresponding water supply temperature, so as to avoid hot water vaporization and water shock. Water is an uncompressible fluid. Once it leaks, it will reduce the pressure. On the contrary, water heating will shrink the volume. If the pressure cannot be stabilized, it will also destroy the equipment in the heating system. Therefore, in order to avoid pressure reduction, vaporization and pressure contraction, the high temperature hot water system must stabilize the pressure in the system, which is constant pressure. There are several ways of constant pressure in hot water heating system:
1) Pressure-fixing method of elevated water tank
The fixed pressure point of this method is located at the inlet or backwater main line of the hot water circulating pump. It is only installed as an elevated water tank. It has simple structure, stable and reliable operation, can stabilize the pressure of the system, and can satisfy the overflow and water supply requirements of the system network. In such a system, the height of the water tank device must satisfy the requirement of non-vaporization of the highest point in the system. Therefore, the position of the device is higher. This constant pressure method is suitable for low temperature water heating system with a small heating range.
2) Adopt the way of constant pressure of replenishment pump
When the pressure of heating system is high, the use of advanced water tank can not guarantee the pressure required by the system. At this time, the way of constant pressure of supply pump should be adopted. This constant pressure method is widely used in the heating system of hot water boilers in the Soviet Union. There are two ways of constant pressure of supply pump: continuous water supply and constant pressure of continuous water supply. The fixed pressure installation of the biomass boiler consists of a supply water tank, a supply pump, a pressure regulator, etc. When the system is in normal operation, the pressure regulator is used to make the supply pump continuously replenish water and make it conform to the leakage of the system, so as to maintain the stability of the system pressure. When the circulating pump is out of operation, the shutoff valve in front of the pressure regulator can be closed. The replenishment pump continues to replenish water to maintain the static pressure required by the system. This constant pressure method does not need to shrink the water tank, so the cost of equipment is low. In addition, the supply pump is also constant pressure, the pump power is not large, and the operation cost is small. Therefore, this method is widely used in China's hot water heating system. The biggest defect of this constant pressure method is that if the power system is suddenly cut off, the supply pump will lose its constant pressure function. In order to avoid water shortage and vaporization of the boiler at this time, the auxiliary installation of pressure water is adopted in the system. When the circulating water pump is running, because of the auxiliary installation of water supply, the circulating water will not be poured back into the pressure rising system. When the circulating water pump and the supply water pump are shut down due to a sudden power cut, the pressure water supply system is put into operation immediately, the check valve is opened automatically, and the pressure water will flow through the hot water boiler and be discharged from the gas collecting tank, thus preventing the boiler water vaporization caused by the residual heat of the furnace chamber. At the same time, the operation is to close the main valve of the supply and return water pipe so as to isolate the heat source from the heat network. The constant pressure of continuous water supply pump of biomass boiler is controlled by electric contact pressure gauge. The inlet pressure of circulating water pump can be maintained in a certain range. When the pressure is below this range, the electric contact pressure gauge acts and connects the motor circuit of the supply water pump. When the supply water pump runs, the supply water and the inlet pressure of the hot water circulating pump rises and exceeds a certain range, the pressure of the hot water boiler will rise. Table is to cut off the supply pump power supply, is the supply pump shutdown. Such reciprocating action, the supply pump continuously replenishes water, and maintains the system pressure to shake in a certain range, so that the system constant pressure mode, because of continuous replenishment, saves electricity than continuous replenishment, but its conditioning and pressure quality is worse than continuous replenishment mode, there are also defects such as pressure fluctuation, frequent contact action of pressure gauge and easy damage.