The slugging for the circulating fluidized bed boiler means that the bubbles in the feed layer converge and grow. When the diameter of the bubbles grows close to the cross section of the bed, the feed layer is divided into several sections to be particle layers with intervals of bubble sections. The particle layers are pushed by bubbles to move upwards to a certain height and then they burst into a large number of small particles that are thrown out of the bed and carried away by bubbles, while the large particles fall down like rain.
Whether the water quality in the gas-fired boiler reaches the required standards is directly related to the safety, performance and service life of boiler. The water must be treated before the boiler operation. However, what are the water quality standards for the gas-fired boiler?
The fuel of coal-fired boiler will release some harmful substances after combustion that are harmful to human body, but also pollute the environment. Therefore, the desulfurization treatment is required for coal-fired boiler, including desulfurization before combustion, desulfurization during combustion and desulfurization after combustion. The specific operating methods are different.
In general, gas-fired boiler uses natural gas to heat water in order to provide heat source for underfloor heating and heating radiator, while condensing gas-fired uses condensation technology to recycle the thermal energy from the exhaust gas.
The fuel of a gas-fired boiler is gas such as natural gas, city gas, biogas and liquefied gas, etc. What kind of fuel the boiler burns is decided by an equipment called a burner. The boiler equipped with a gas-fired burner is called a gas-fired boiler. There are three methods of gas-fired boiler combustion as per technical characteristics of how the gas and air mix.
1. Diffusion combustion:
Gas and air mutually diffuse at the gas nozzle and are burning. The advantages are burning stably and with simple burner structure. However, the heated area is easy to be carbonized due to long flame, which is easy to produce incomplete combustion.
2. Premixed combustion:
A part of air and gas are premixed before combustion (coefficient of primary air surplus is between 0.2-0.8), and then being burned. The advantages are clear combustion flame, enhanced combustion, and high thermal efficiency.
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.
