The common causes of failures of heat transfer oil electric heaters during production operations include: poor quality of heat transfer oil, leakage of heat transfer oil, excessive temperature of heat transfer oil system outlet, combined with low heat transfer oil flow rate, improper handling during power failure These four aspects account for more than 70% of the failure rate. Today we will focus on the four main failure phenomena.
First, the poor quality of heat transfer oil The poor quality of heat transfer oil is manifested in the following aspects. The first is that heat transfer oil is mixed or adsorbed with moisture in the air during storage and transportation. When the heat-conducting oil mixed with water is heated to 100 ° C, it is easy to cause boiling oil to overflow, which may cause an explosion or explosion under the action of fire. Secondly, the residual carbon in the heat transfer oil exceeds the standard. During the heating operation of the heat exchange system, the heat transfer medium generates some cracking and condensation reactions at high temperatures to generate a certain amount of colloidal polymer. At the same time, some superheated medium will also generate coke. Polymer and residual carbon are insoluble in oil and suspended in oil. During operation, these materials will be deposited on the bottom of the drum and overheated, and deposited on the tube wall and overheated and burst the tube. Therefore, the heat transfer oil is regularly sampled and analyzed to timely grasp the changes in the quality of the oil, analyze the reasons for the change, and regularly replenish the amount of new heat transfer oil so that the amount of residual carbon is basically stable. Corresponding measures should be taken in time.
Second, the heat transfer oil system outlet temperature is too high, and the heat transfer oil flow rate is too low, sometimes due to the high oil temperature, the heat engine temperature can not go up, can not meet the production needs. Some units take measures to increase the outlet temperature to ensure heat supply. As a result, the outlet temperature is close to or even exceeds the maximum allowable temperature of the heat carrier, thereby increasing the degree of coking and fouling. The vicious cycle was continued until the furnace tube burst. In addition, an excessively low flow rate will cause the temperature of the inner wall of most or a part of the pipe on the heating surface to be higher than the allowable oil film temperature, which shortens the normal service life of the heat transfer oil, resulting in overheating and bulging and tube bursting. Therefore, the maximum outlet oil temperature of the boiler should be about 30 degrees Celsius lower than the operating temperature of the heat carrier to prevent the oil from overheating and deteriorating 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 accidents such as residual carbon, blockage of the pipe diameter, and overheating of the pipe wall.
3. Fire caused by leakage of heat transfer oil If there is a problem with the welding parts of the heat transfer oil electric heater, a large amount of vaporization will occur in the case where the welded part of the heat transfer pipe is off or overheated, which will cause pipeline vibration or even damage, resulting in a large amount of heat transfer oil leaking and heat conduction The oil has strong permeability, especially the flange gasket is more serious. Fires often occur after encountering fire sources after leakage. Therefore, when installing, you must choose a qualified installation company to install. The pipe connection should be welded, and flange connection should be used appropriately. Screw connection should not be used. The flange connection should use oil-resistant, pressure-resistant, high-temperature-resistant high-strength graphite products. Used as a gasket. All accessories in contact with the heat carrier must not be made of non-ferrous metals and cast iron. Steel pipes should be made of steel seamless pipes, fasteners, and especially the connecting bolts on the main circuit. Steel drums are more appropriate. Before the boiler is ignited, a pressure test should be performed on all pipes and valves by the boiler supervision institute and the installation company until no leakage occurs. The thermal oil should circulate in the system pipeline for not less than one hour. After careful inspection, To start up.
Fire caused by improper handling during power failure
在正常使用时，如果偶尔发生突然停电，此时循环油泵停止工作，炉膛内燃煤继续在燃烧，使锅炉油温度继续升高，如果油温上升太快降不下来，就会在短时间内油温局部超高而结焦，致使超温过热爆管引起火灾。 In normal use of the heat-conducting oil furnace heater , if there is an occasional sudden power failure, the circulating oil pump stops working at this time, and the coal combustion in the furnace continues to burn, so that the boiler oil temperature continues to rise. If the oil temperature rises too quickly and does not fall, then In a short time, the oil temperature will be locally high and coking, resulting in overheating and overheating the tube and causing a fire. Therefore, in the event of a power outage, etc., all furnace doors should be opened to immediately eliminate the remaining coal burning in the furnace, allowing a large amount of cold air to penetrate into the furnace, quickly reducing the furnace temperature and eliminating heat sources; simultaneously opening the boiler oil drain valve to slow 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 the heat in time. Conditional units can be equipped with dual power sources, such as a small gasoline generator, whose circuit and the circulating oil pump circuit are switched between each other, so as to prevent coking caused by the excessively high oil temperature in a short time after a power outage and prevent unnecessary power outages caused by power outages. The accident happened.