I. principle of incinerator
Liquid (gas) fuel is burned in the radiation chamber (furnace) of the incinerator, which produces high-temperature flue gas and uses it as a heat carrier, flows to the convection chamber, and is pushed out from the chimney. The crude oil to be heated begins to enter the convection chamber tube of the incinerator, and the crude oil temperature is generally 29. The heat of the furnace tube is obtained from the flue gas (9) flowing through the convection chamber by convection method. The heat is transferred from the external surface of the furnace tube to the external surface of the furnace tube by heat transfer method, and then transferred to the active crude oil in the tube by convection method. Crude oil enters the furnace tube of the radiation chamber from the convection chamber furnace tube. In the radiation chamber, the flame emitted by the incinerator radiates one side of the heat to the external surface of the furnace tube by the radiation method, and the other side radiates to the furnace wall laying the furnace tube. The furnace wall radiates the heat to the external surface of the furnace tube on the side of the back fire surface by the radiation method again. The two-sided radiant heat are used together to raise the temperature of the external surface of the furnace tube and cause the temperature difference between the external surface and the external surface of the tube wall. The heat flows to the inner wall of the tube by conduction method, and the active crude oil in the tube obtains heat from the inner wall of the tube by convection method, thus completing the process request of heating crude oil.
The heating capacity of the incinerator depends on the strength of the flame (furnace temperature), the appearance of the furnace tube and the total heat transfer coefficient. The stronger the flame, the higher the furnace temperature, the greater the temperature difference between the furnace and the oil flow, and the greater the heat transfer; the larger the area of the furnace tube where the flame and the flue gas touch, the more heat transfer; the better the heat transfer function of the furnace tube, the more reasonable the furnace layout, and the more heat transfer. The strength of the flame can be adjusted by mastering the skill of the nozzle. But for the furnace with certain layout, the temperature of the furnace will not rise after reaching a certain value under normal operation. The total heat transfer coefficient of furnace tube appearance is inevitable for a furnace, so the heating ability of each furnace has certain limitations. In practical application, poor flame incineration and coking of furnace tubes affect the heating ability of the incinerator, so it is necessary to pay attention to the incinerator to make it burn completely, and prevent coking due to too high temperature of some furnace tubes.
Operation parameters of two incinerators
Furnace temperature (retaining wall temperature)
Furnace temperature generally refers to the temperature of flue gas leaving the radiation chamber, that is, the temperature of flue gas not entering the convection chamber or the temperature in front of the fire wall of the radiation chamber, which is a tight parameter for the operation of the incinerator. The heat generated by fuel incineration in the furnace (radiation chamber) is radiated and distributed to the furnace tube. The magnitude of heat transfer is related to furnace temperature and tube wall temperature. The heat of crude oil obtained from the incinerator is mainly radiation heat transfer. The radiation heat transfer is directly proportional to the fourth power of the overall temperature of the flame. Therefore, in the high-temperature zone, the heat absorption result of the radiation heating surface is better than that of the convection heating surface, and the heat consumption required by the radiation heat transfer is less than that of the convection heat transfer. The furnace temperature selected in the plan determines the heat absorption ratio between the radiant heating surface and the convective heating surface of the incinerator. If the furnace temperature is high, the radiant chamber will transmit more heat. Therefore, the furnace temperature can vividly reflect the furnace outlet temperature. However, from the perspective of operation, the furnace temperature is too high, and the heat intensity of the furnace tube in the radiation chamber is too large, which may cause the part of the radiation tube to overheat and coke, and the flue gas temperature entering the convection chamber is too high, and the furnace tube in the convection chamber is easy to be burned out, so that the flue gas temperature is too high, and the heat of the incinerator is subject to falling. So the furnace temperature is the goal of ensuring the safe operation of the incinerator forever. The furnace temperature is very high in the oil transportation incinerator.
Exhaust gas temperature
The flue gas temperature is the temperature of a group of convective heating surfaces entering the chimney after the flue gas leaves the incinerator. The exhaust gas temperature should not be too high, or the heat loss will be large. During the operation, the exhaust gas temperature shall be controlled, and the exhaust gas temperature shall be lowered when the incinerator is in the environment of complete incineration under negative pressure. The adjustment of the exhaust gas temperature is usually controlled by the intake air volume, i.e. the facility to adjust the excess atmosphere coefficient. Lowering the exhaust gas temperature can reduce the loss of exhaust gas heat of the incinerator and improve the heat compliance, thus saving fuel consumption and lowering the operating cost of the incinerator. However, the temperature transition of exhaust gas is too low, which makes the heat transfer temperature difference between the flue gas and the heat carrier at the end of the convective heating surface low, increases the metal consumption of the heating surface, and advances the investment price of the incinerator. Therefore, the selection of exhaust gas temperature shall be through economic comparison.
When choosing a very reasonable exhaust temperature, we should also consider the impact of low temperature erosion. Because the burning sulfur can produce +. It neutralizes the water vapor in the flue gas to create sulfuric acid vapor. When the wall temperature of the heating surface is lower than the dew point temperature of the sulfuric acid vapor, the sulfuric acid vapor will condense and corrode the metal on the wall. If the wall temperature of the heating surface is lower than the dew point of the water vapor in the flue gas, the water vapor will also freeze on the pipe wall, aggravating the erosion and easily causing ash blocking. The mistakes of lowering dew point, reducing erosion and ash accumulation are: purifying fuel oil. At present, it has been used internationally, but whether it can be widely used is still worth studying.
——Author：ebico