Precautions for coal-fired boiler transformation - self recycling burner

Precautions for coal-fired boiler transformation
The long-standing problems of coal-fired boilers, such as large areas of pollutants, small monomer capacity, emissions close to the ground, and mismatches between main and auxiliary engines, have been magnified again. The transformation of coal-fired boilers will undoubtedly become the focus of urban air pollution control in the next step.
I. Basic principle of changing coal-fired boiler into oil-fired (gas) boiler.
1. The reformed coal-fired boiler must meet the following conditions:
① The pressure parts of the original boiler are basically intact and have the value of continuous use;
② The water and gas system, air supply and induced draft system of the original boiler shall be basically intact.
2. The modified boiler shall achieve the following purposes:
① Keep the rated parameters of the original boiler (such as steam pressure, steam temperature, return water temperature, etc.) unchanged;
② Maintain or improve the output and efficiency of the original boiler.
3. The purpose of eliminating smoke and dust is achieved through transformation to meet the requirements of environmental protection.
4. The boiler transformation scheme must be simple, easy, less investment, quick effect and short construction period. Therefore, the smaller the scope of boiler transformation is, the better it can be achieved only through boiler transformation and combustion device. The transformation part does not exceed the basic structure scope of boiler body.
2、 Problems to be paid attention to when changing coal-fired boiler to oil (gas) boiler.
1. To change to mechanized stratified combustion of oil (gas) boiler, first remove the front and rear arches, and consider adding the bottom heating surface to replace the grate to prevent the grate from overheating and burning.
2. For small boilers that change coal to oil (gas) fired boilers, that is, from the original negative pressure combustion to the current micro positive pressure combustion, attention must be paid to the wall structure and sealing.
3. The type selection and arrangement of burners are closely related to the furnace form. The flame in the furnace should be filled well without forming a dead angle of air flow; Avoid mutual interference of adjacent burner flames; Keep the flame at the center of the furnace at low load to prevent the flame center from deviating from the symmetrical center of the furnace; The mixture of unburned gas shall not contact the heating surface to avoid incomplete combustion of gas; High-temperature flame shall avoid scouring the heating surface at high speed and overheating the pipe wall due to excessive heat intensity of the heating surface. The layout of the burner shall also take into account the layout of the gas pipeline and the reasonable layout and use of the pipeline.
4. The flue gas velocity of the convection heating surface of the oil-gas-fired boiler is not limited by the fly ash wear condition, and the flue gas velocity can be appropriately increased to increase the heat transfer coefficient of the convection heating surface; For boilers with superheated gas, the heating area shall not be increased. Attention shall be paid to the capacity of the furnace steam-water separator to ensure the steam quality, especially for boilers with superheated gas.
5. To prevent high temperature corrosion, change coal to fuel oil, because the fuel oil contains metal elements such as sodium and vanadium, and the melting point of oxide eutectic crystals after combustion is very low, generally around 600 ℃, or even lower. After sublimation at high temperature in the furnace, this kind of oxide forms corrosive high-temperature ash deposit on the heating surface with relatively low temperature, and the corrosion rate is faster. Therefore, during the transformation, special coatings such as ceramic and silicon carbide should be coated on the surface of the heating surface that is prone to high-temperature corrosion, and materials with good high-temperature corrosion resistance can also be selected to improve its high-temperature corrosion resistance.
6. To prevent explosion in the boiler, when coal is changed to oil (gas) boiler, when the oil atomization is poor or the oil droplets (gas) with incomplete combustion are gathered by hot gas in the furnace or tail, due to the danger of fire, explosion, etc., the explosion-proof door shall be installed at the proper position of the boiler, and the ignition program control and flameout protection device shall be added to the automatic control to ensure the safe operation of the boiler.