Thermal Oil Boiler Fire prevention

ONE / Pipe burst fire

1. The oil quality is poor, and the carbon residue index in the oil exceeds the standard. When the heat transfer oil is inadvertently mixed with moisture, impurities or other oils during storage, transportation or operation and maintenance, when the heat transfer oil is heated to 1000C, it will cause oil injection and fire, or the moisture will vaporize and generate high pressure when heated, causing equipment The overpressure explosion. In addition, the index of residual carbon in the oil exceeds the standard. The heat transfer oil will undergo some chemical changes during the heating operation to generate a small amount of high polymer. At the same time, it will also generate coke due to local overheating. These high polymers and carbon residue are insoluble in the oil and suspended in the oil. During operation, these substances will deposit on the bottom of the drum and overheat and bulge, and deposit on the tube wall and burst the tube due to overheating. Therefore, regular sampling and analysis of the heat transfer oil, timely grasp of the quality change of the oil, analyze the reasons for the change, regularly supplement the amount of new heat transfer oil, so that the residual carbon amount is basically stabilized, and the heat transfer oil added to the boiler must be dehydrated in advance to find problems. Corresponding measures should be taken in time.

1. The outlet temperature is too high and the flow rate is too low. Sometimes due to the high oil temperature, the heat engine temperature cannot rise, which cannot meet the production needs. Some units have adopted the method of increasing the outlet temperature to ensure the heat supply. As a result, the outlet temperature is close to or even exceeds the maximum allowable use temperature of the heat carrier, thereby increasing the degree of coking and fouling. The heat transfer efficiency of the radiator using the heat engine is lower. The vicious circle is repeated until the furnace tube bursts. In addition, too low a flow rate will cause the temperature of most or part of the inner wall of the tube on the heating surface to be higher than the allowable oil film temperature, which will shorten the normal service life of the heat transfer oil, resulting in overheating and tube bursting. Therefore, the maximum outlet oil temperature of the boiler should be about 30°C lower than the working temperature of the heat carrier to prevent the oil from being overheated and degraded during use. During operation, the flow rate of the heat transfer oil in the radiant heating surface tube is not less than 2m/s, and the convection heating tube is not less than 1.5m/s to prevent the occurrence of carbon residue, blockage of the pipe diameter, and overheating of the pipe wall.

TWO / Leak fire

Due to welding quality problems, the welding seam of the heat transfer main pipe is partially peeled off or a large amount of vaporization occurs under over-temperature conditions, causing vibration or even damage to the pipeline, resulting in a large amount of heat transfer oil leaking, and the heat transfer oil has strong permeability, especially at the flange gasket. Severe, fires often occur after the leak is met with a fire source. Therefore, when installing, choose a qualified installation company. The pipe connection should be welded, and flange connection should be properly supplemented. Screw connection should not be used. The flange connection should be made of high-strength graphite products with oil resistance, pressure resistance and high temperature resistance. As a sealing gasket. All accessories in contact with the heat carrier must not be made of non-ferrous metals and cast iron. The steel pipe should be made of 20# steel seamless pipe, and the fasteners, especially the connecting bolts on the main circuit, should be made of 35# steel drum. Before the boiler is ignited, the boiler supervisory office and the installation company should conduct a pressure test on all pipes, valves, etc., until there is no leakage. The heat transfer oil should not circulate in the system pipeline for less than 60 minutes. After confirming that everything is normal, It can be fired.

THREE/ Blackout fire

When the heat-conducting oil boiler is in normal use, the unit occasionally has a sudden power failure. At this time, the circulating oil pump stops working, and the coal in the furnace continues to burn, so that the boiler oil temperature continues to rise. If the oil temperature rises too fast and cannot fall, it will In a short period of time, the oil temperature is locally super high and coking occurs, causing the overheating and overheating of the pipe to cause fire. Therefore, in the event of a power failure and other failures, all furnace doors should be opened to immediately eliminate the remaining coal in the furnace, let a large amount of cold air flow into the furnace, quickly reduce the furnace temperature and eliminate the heat source; open the boiler oil drain valve simultaneously to slow down the high temperature oil Slowly put it into the oil storage tank, and let the cold oil in the expansion oil tank slowly flow into the boiler to take away heat in time. Conditional units can be equipped with dual power sources, such as a small gasoline generator, whose circuit and circulating oil pump circuit are switched to each other, so as to prevent excessive oil temperature in a short period of time after a power failure, which may cause coking and cause accidents.

In addition, furnace workers must be trained and qualified by the technical supervision department and issued a “fireman operating certificate”. Only those who have a license can operate independently to ensure that abnormal situations can be eliminated in time. It is also necessary to keep the circulating oil pump and the oil storage tank clean, remove the grease and dust accumulated on the surface at any time, and prevent them from being ignited by external flying fires.