Analysis of the reasons for fouling of the diesel burner of the heat-conducting oil boiler

The thermal oil boiler diesel burner refers to the boiler diesel burner heated by the thermal oil. Heat transfer oil, also known as organic heat carrier or heat medium oil, has been used as an intermediate heat transfer medium in industrial heat transfer processes for more than 50 years. The boiler diesel burner is developed based on the design concept of forced circulation. Generally, coal, petroleum, and natural gas are used as fuels, and heat transfer oil is used as a medium. The hot oil circulation pump is used to force the medium to circulate in the liquid phase. The heat energy is transferred to the heating equipment and then returned to the heating furnace for reheating. 1. Types of heat transfer oil Heat transfer oil is generally pided into two types: mineral type and molding type. The mineral form is part of the high-boiling fraction extracted from petroleum refining to which antioxidants are added to become heat transfer oil. Synthetic heat transfer oil is usually a mixture of several isomers or similar chemicals. The composition of heat transfer oil includes biphenyl, naphthalene, diphenyl ether and their low melting point mixtures. Common types include alkyl benzene type, alkyl naphthalene type, alkyl biphenyl type, mixed biphenyl and diphenyl ether, hydrogenated triphenyl type, benzyl toluene type, heavy alkyl benzene type, silicone type , Mineral oil type 2. Disadvantages of heat transfer oil The heat transfer oil is easily oxidized during heating. Its kinematic viscosity gradually increases, which is due to the pyrolysis and thermal condensation reaction of the heat transfer oil components at high temperatures. The pyrolysis reaction results in the formation of small molecular compounds, reducing their viscosity. However, thermal polycondensation produces a polymer product, which increases its viscosity. Small molecule compounds have a small amount of volatilization, and the overall result is an increase in oil viscosity. The amount of carbon residue increases with increasing temperature. When the operating temperature is 300~400℃, thermal cracking is prone to occur. In the pipeline, carbon is formed on the inner wall of the equipment, which affects the heat transfer efficiency, accelerates the aging and failure of the heat transfer oil, and also causes the furnace body and the pipeline to locally overheat, damage the mechanical force and endanger personal safety. The fouling of the heat transfer oil in the pipeline tube reduces the circulation area of ​​the pipeline, increases the friction resistance, increases the energy consumption of the pipeline, and reduces the oil transportation capacity of the pipeline. Sometimes, it can even cause accidents, such as initial condensation and flow stop. In addition, the grease and coke produced by the heat transfer oil will increase the thermal resistance of the pipe wall, increase the energy consumption in the production process, shorten the service life of the equipment, reduce the internal diameter of the equipment, increase the pressure drop of the material flow, reduce the output, and shorten the operation cycle, which is serious affect production. 3. Causes of thermal grease stains High-temperature thermal oil circulates thermal energy in the thermal oil furnace and produces colloids. Glue is sticky, and a good heat transfer oil can suspend the glue in the oil. During the cycle, part of the glue can be filtered out through the filter. However, if a small amount of glue is attached to the inner wall of the furnace tube, it is easy to form coking. In addition, if there is a series of air in the process of heat transfer oil circulation, it is easy to degrade and polymerize, forming low boiling point substances and high boiling point substances. The low boiling point can be discharged into the atmosphere through the high tank, and a small amount of high boiling point can be dissolved in the heat transfer oil. However, if the solubility of the heat transfer oil reaches a subsaturated state, the high boiling point will adhere to the inner wall of the tube, which is another cause of coking. In addition, operating temperatures exceeding its design temperature often result in autocatalytic thermal decomposition, leading to coking in the tube. The leakage of process materials into the heat transfer oil system, the formation of corrosion products, the formation of rust, and the contamination of impurities during the overhaul will cause the inner wall of the pipeline to coke. 4. The main components of heat transfer oil and dirt. Grease dirt is mainly composed of wax, colloid, coke, pitch, carbide, carbon, iron sulfide, iron oxide, inorganic salt, organic polymer, catalyst, etc. 5. Damage caused by thermal grease. A small amount of light components in the heat transfer oil system can be discharged through the exhaust pipe, but too much light components will result in low pumping flow and interlocking shutdown of the furnace. Recombination will cause coking in the furnace tube and reduce the heat transfer rate. The thermal efficiency of the hot oil furnace is reduced, resulting in energy waste, and the temperature difference between the inside and outside of the furnace tube increases. When the temperature of the outer wall of the furnace tube reaches 600~700℃, it is easy to burn through the furnace tube, causing fire, equipment damage, and even casualties. Coking is the natural enemy of the thermal oil boiler diesel burner and the cause of fire. Due to the above shortcomings of heat transfer oil, the usual solution is to clean and remove dirt. ! If you are interested in diesel combustion engines, please contact us for a quote!