The main equipment functions of the gasifier system: (2)
The role of the electrostatic tar detar eliminator
The volatile compounds in coal produce post-tar during dry distillation. It leaves the furnace with the gas in the form of a mist, when the gas is initially cooled in the air cooler, the heavy tar fraction with high boiling point can be removed by condensation, while the light tar with low boiling point is retained in the gas, these tars are difficult to remove with general water washing, and special tar removal devices are needed to capture, and electric tar removal is to achieve the purpose of removing tar by means of high-voltage static electricity to make the tar mist in the gas move electrically and directionally. It is a highly efficient tar removal equipment with low power consumption (0.5 kWh/1000 standard m3 with a tar removal efficiency of up to 95%-99%).
There are three kinds of common electric tar removal devices: tubular type, concentric circle type and plate type, and our electric tar removal device is a tubular type, which is equipped with several Φ219 pipes according to the needs of the process.
After the gas enters the electric tar remover, it enters the sedimentation electrode through the gas separation partition, and the precipitation electrode is grounded and positively charged. In the middle of the second stage, 30-60 kV high-voltage direct current is supplied, and when the gas passes between the precipitating electrode and the corona electrode, the gas is ionized due to the action of the high-voltage electric field, so that this area is filled with positive and negative ions and electrons. Positive ions are absorbed by the corona electrodes, while negative ions and electrons attach to suspended solids such as tar and dust, making them negatively charged.
According to the principle of same-sex repulsion and out-of-phase attraction in the electric field, the negatively charged tar and dust move to the positive electrode to avoid contact with the tube and lose their charge and accumulate on the precipitating electrode, fall to the lower part of the electric tar remover under its own weight and discharge it through the valve, and the gas is also exported from the upper gas outlet.
In order to ensure the fluidity of the tar, there is an insulating layer on the outside of the electric tar removal tank, and a steam heating tube is installed in the lower cone.
The temperature of the gas entering the electric tar removal device is generally controlled at 85-90 °C, and the tar removal efficiency is high at this time. If the temperature is too low, it is easy to make the gas reach the dew point, and the water will be precipitated in the form of fog, so that the tar removal efficiency is low.
In order to dare to introduce direct current and support corona electrodes, the top of the electric tar remover is equipped with a support or suspension insulator. In order to protect the safe operation of the insulator and avoid the condensation and damage to the electric field caused by the influence of temperature, the insulator is set in the insulating box air, and the outer edge is wrapped with a steam jacket, so that the external temperature of the insulator is higher than the temperature of the gas, so that the moisture in the gas cannot condense to the inner surface of the insulator and ensure the safety of operation.
In order to ensure the safe operation of the electric tar remover, it is not allowed to run the gas under negative pressure.