Guide: The steam boiler is a pressure vessel. The sufficient condition for the safe operation of the boiler is that the pressure and temperature of the boiler are controlled within a safe range. Then, how to control the pressure and temperature of the steam boiler? The hot water boiler operating system is more complicated, including the boiler system and piping system, how to adjust the hot water boiler system.
The steam boiler is a pressure vessel. The sufficient condition for the safe operation of the boiler is that the pressure and temperature of the boiler are controlled within a safe range. Then, how to control the pressure and temperature of the steam boiler? The hot water boiler operating system is more complicated, including the boiler system and piping system, how to adjust the hot water boiler system.
1. Steam boiler pressure and temperature control method
1. When the load decreases and the vapor pressure rises, if the water level is low at this time, the water supply can be increased to prevent the vapor pressure from rising, and then reduce the fuel and air volume as appropriate, weaken the combustion, reduce the evaporation, and keep the vapor pressure normal .
2. When the load decreases and the steam pressure rises, if the water level is also high, first reduce the fuel volume and air volume to weaken the combustion, while appropriately reducing the water supply. After the steam pressure and water level are normal, adjust the combustion and water supply according to the load.
3. When the load increases and the vapor pressure drops, if the water level is low at this time, you can increase the fuel volume and air volume first to strengthen the combustion, and at the same time slowly increase the water supply volume to restore the vapor pressure and water level to normal; you can also increase the water supply volume first After the water level is normal, increase the combustion to restore the vapor pressure to normal.
4. When the load increases and the vapor pressure drops, if the water level is high, you can first reduce the water supply, then increase the fuel and air volume, intensify the combustion, increase the evaporation volume, and the negative air pressure will return to normal. For boilers that interrupt the water supply, the water supply should be even, the interval between water supply should not be too long, the water supply should not be too much at one time, and the water supply should not be used when the combustion is weakened to keep the vapor pressure stable.
5. When purchasing a boiler, users should carefully consider various comprehensive factors. Don't just pay attention to the price of the boiler, and choose the boiler equipment that really suits you.
2. Hot water boiler system adjustment method
1. Operating parameter control
Maintain the pressure. During the operation of the hot water boiler, the inlet and outlet pressure gauges of the boiler and the circulating water pump inlet pressure gauges should be closely monitored. If large pressure fluctuations are found, the cause should be searched for and dealt with in time. When the system pressure is low, water should be added to the system in time, and the combustion should be adjusted according to the requirements of heat supply and water temperature. When a local fault occurs in the network system and needs to be cut off, the circulating water pressure should be monitored more closely. If the pressure changes greatly, the valve should be adjusted accordingly to ensure that the total operating network pressure remains unchanged.
Temperature control, the furnace staff should always pay attention to the change of outdoor temperature, and adjust the amount of combustion in time according to the specified curve of the relationship between water temperature and air temperature. The method of centralized adjustment in the boiler room should be selected according to the specific situation. Generally, it is required that the difference between the network water supply temperature and the temperature value specified by the water temperature curve is no more than ± 2 °C. If the quality adjustment method is adopted, the temperature of the network water supply should be changed gradually, and the hourly water temperature increase or decrease should not be greater than 20. C, so as to avoid abnormal temperature stress in the pipeline. During the operation of the hot water boiler, always pay attention to the changes of the pressure gauge and thermometer on the boiler and its pipes. For hot water boilers with regulating valves in each external circulation loop, the return water temperature of each circulation loop should be compared frequently during operation, and attention should be paid to adjust so that the temperature deviation does not exceed 10°C.
2, matters needing attention during operation
(1) When starting a large circulating water pump, the bypass valve should be opened first to prevent damage to the boiler or radiator due to the start-up of the pressure rise too fast. After the boiler is operating normally, open the main water valve and close the bypass valve.
(2) During operation, as the water temperature rises and the make-up water enters the boiler, gas will continue to evolve, and the bleed valve should be opened frequently for exhaust.
(3) The hot water boiler should also be drained regularly through the blowdown valve during operation. When blowdown, attention should be paid to the stability of the pressure in the boiler to avoid water hammer caused by boiler water vaporization. The network system discharges sewage through the sewage device.
(4) The water supply of the hot water heating system should be reduced as much as possible. Water leakage should be repaired in time. At the same time, the management of air venting and drainage devices should be strengthened. It is forbidden to discharge hot water for other purposes. Under normal circumstances, the system's water replenishment volume should be controlled within 1% of the system's circulating water volume
(5) In the system network of gravity-type natural circulation, the expansion pipe of the expansion tank should be installed on the boiler water supply (outlet) main pipe. Valves are strictly prohibited on the expansion pipe, and anti-freezing measures are provided.
(6) The circulating water should maintain a certain flow rate and flow evenly into each heating surface to prevent vaporization.
(7) There should be proper power failure protection measures. When the natural circulation hot water boiler suddenly loses power, it can still keep the boiler water circulating, which poses little threat to safe operation. However, when a forced-circulation hot water boiler suddenly loses power and forces the pump fan to stop running, the boiler water circulation will stop immediately, which is prone to serious accidents due to vaporization. At this time, you must quickly open the furnace door and the economizer bypass flue (when there is an economizer), remove the coal fire in the furnace or use wet furnace ash to suppress the coal, so that the furnace temperature is quickly reduced, and the boiler should be Use a valve to shut off with the system. If the feed water (tap water) pressure is higher than the static pressure of the boiler, water can be fed into the boiler, and the boiler relief valve and bleed valve can be opened to make the boiler water flow and cool down at the same time until the residual heat in the furnace is eliminated. Some larger boiler rooms are equipped with backup power sources or diesel engines. When the power grid fails, they should be started quickly to ensure that the water circulation in the system is not interrupted.
(8) In order to coordinate the operation of the boiler's combustion system and the water circulation system to prevent accidents and expansion, it is best to interlock the boiler coal ventilation and other equipment with the water pump, so that once the water circulation stops, the furnace will be extinguished.
(9) Nowadays, environmental protection is promoted in various places, especially the nitrogen reduction of boilers. Users should pay attention to local environmental protection requirements when purchasing boilers and choose suitable boilers.
The above introduces the steam boiler pressure and temperature adjustment and the hot water boiler system adjustment method. Whether it is a steam boiler or a hot water boiler, safe operation and stable working conditions are essential. The boiler staff must always control the boiler within the normal range to ensure The boiler runs safely and stably.