Failure cause of overheating deformation of glass lined reactor

Glass lined reactor is a kind of chemical reaction equipment, so great attention must be paid in use, otherwise it will be damaged due to various reasons, and eventually affect the normal operation of the equipment. As the reaction kettle is under the working condition of high temperature and high pressure for a long time, overheating deformation, wall thickness thinning, material performance degradation and other phenomena often occur in the use process. If it is not solved in time, it will seriously threaten the safe use of the pressure vessel, and even may cause very serious consequences. Therefore, the management of inspection and use should be strengthened when using the reactor to avoid safety accidents. Today, the manufacturer briefly talked about the cause of overheating deformation and failure of glass lined reactor. Come and have a look.

1、 Material factor

The steel used for glass lined reactor is a kind of medium temperature hydrogen resistant steel. Normalization+tempering is often used for heat treatment. When the temperature is below 550 ℃, it has high endurance strength, but under the action of long-term constant temperature and stress, plastic deformation creep will slowly occur. The creep temperature of different materials is different. The alloy steel will creep when the temperature exceeds 350~400 ℃. Generally speaking, the metal will show obvious creep only when the temperature exceeds 0.3-0.4Tm (Tm is the melting point of the material, in K). The reactor operates at 300~400 ℃ for a long time, and the creep factor has a great influence on the deformation failure.

2、 Medium factor

The medium used in the reactor is coal tar pitch, which is a black solid at normal temperature without fixed melting point. It is softened after being heated and becomes liquid at high temperature. It is not easy to flow below 180 ℃, and its density reaches 1.2kg/m3. The role of the reactor is to remove flash oil by heating and pressurizing. Although there are three layers of mixing devices installed inside the container, due to the small specific heat capacity of this medium, it is not conducive to the absorption and transmission of heat. The presence of local high temperature at the lower part of the cylinder causes asphalt to coke on the inner wall of the container, which can reach a thickness of 3-4 cm, forming an insulating layer, which is not conducive to heat transfer. Large amount of heat accumulation provides temperature conditions for over burning and creep.

3、 Heating mode factor

The reactor vessel is directly heated by flame.

Two weeks of fire resistant walls shall be built at 300mm around the periphery of the vertical reactor vessel, and a combustion chamber shall be built at the lower part of the cylinder. The coke oven gas shall directly contact the vessel wall for side heating, and work 24 hours a day. The flame temperature reaches about 900 ℃, the flue temperature reaches 700 ℃, and the flue outlet temperature reaches 500 ℃. In use, it operates for a long time beyond the design temperature. In this heating mode, the heat is too concentrated and the local temperature is too high, causing local overheating and deformation of the container barrel.

4、 Flue gas flow factors

The insulation wall was not installed according to the design drawings. High temperature flue gas fails to realize heat exchange at the first floor and directly rises to the second floor. It enters the third floor after rotating 180 ° around the barrel at the second floor, enters the fourth floor after rotating 90 ° at the third floor, enters the fifth floor after rotating 90 ° at the fourth floor, and enters the chimney for emission after rotating 180 °. Such flue gas process layout is unscientific, and the high-temperature flue gas on the first floor basically does not rotate around the cylinder for heat exchange, resulting in the high temperature of the high-temperature flue gas at the corner of the second floor, causing overheating deformation here. There are flue gas short circuits in each layer of flue gas, which can not achieve full heat exchange, low heat exchange efficiency, and waste of energy.