Boiler steam pressure control refers to maintaining the steam pressure of boiler drum by adjusting the fuel control system. Its basic task is to adapt the heat provided by fuel combustion to the steam load of boiler drum. At the same time, it is necessary to ensure the safe and economic operation of boiler drum and meet the requirements of environmental protection.
According to the power of water or steam circulation, boilers can be divided into natural circulation boilers, forced circulation boilers, once-through boilers and combined circulation boilers.
If the boiler gives overpressure indicator which affects boiler's safe operation, depressurization measures should be taken. However, please pay attention that depressurization can not be too fast. After the overpressure problem of steam boiler is solved, we should check the internal and external parts of boiler to ensure that everything is going well.
Here load means, amount of steam drawn from the boiler. So when the load increases, the specific volume of the steam in the boiler increases reducing the pressure. This inturn demands for more feed water and more amount of fuel to be burnt. So, for any boiler there will be a feed water level control system put in place to measure the water level in drum. As and when the level of water in the drum reduces, the controller sends a signal to the feed water pump to start and stops when the desired water level is reached. This way the steam generation continues to maintain the desired pressure.
The coal-fired steam boiler is a forced circulation high-pressure single-tube DC boiler. Its operation process includes three processes: the combustion process of the fuel, the heat transfer process of flue gas to water and the vaporization process after water absorbs heat. In order to better control these different processes, the control system should make
the heat of pulverized coal combustion adapt to the requirements of steam load changes and dryness.
Loads vary, and a power plant must be capable of handling the minimum load, the maximum load, and any load variations. Boiler selection is often dictated by the variation in load demand, rather than by the total quantity of steam or hot water required. There are three basic types of load variations: seasonal, daily, and instantaneous.
The choice between a steam system or a thermal fluid system is governed by the process requirements. The range or process temperature is a deciding factor. If the system’s required temperature is above the freezing point of water (0°C) and below approximately 160°C, the choice is usually steam. However, if the required temperature is above 160°C, thermal fluid may be a better solution. Thermal oil heater systems can be designed with maximum operating temperatures to 325°C.
The boiler gas consumption calculation need the following parameters: gas calorific value and boiler thermal efficiency.
Theoretically, the gas consumption of boiler = boiler thermal capacity ÷ (calorific value of gas x boiler thermal efficiency )
Take the 1 tph steam boiler as an example:
= 600,000 cal / (8500Kcal * 0.98) =72m3/h, the 1 tph boiler's gas consumption per hour is about 72 cubic meters.
