Structure overview of electrostatic precipitator (ESP)

The corona electrode system is the most important component for generating corona and establishing an electric field, which determines the strength of the discharge. Affecting the performance of dust charging in the flue gas is directly related to the dust removal efficiency. In addition, its strength and reliability are also directly related to the safe operation of the entire electrostatic precipitator. Therefore, the corona electrode system is the design, manufacture and key components for installation. Must choose good line, reasonable structure and suitable rapping. Strict pole spacing should be ensured during installation to ensure good insulation performance and sufficient discharge distance between the entire corona pole system and other components of the electrostatic precipitator. In actual operation, the corona electrode system often occurs due to rapping, thermal expansion, dust accumulation, etc., causing the electrode plate or electrode line to deform slightly, causing the electrode spacing to change. The direct performance in operation is that the secondary voltage rises to a lower voltage. Flashover occurs, the secondary voltage cannot be maintained at a high level, and the dust removal performance deteriorates.

3. Dust collector system
The dust collection electrode system is composed of several rows of electrode plates and corona electrodes arranged alternately, together with the corona electrode to form an electric field. It is an important part of dust deposition and directly affects the efficiency of the electrostatic precipitator. Dust collectors are generally rolled from steel.
4. Channel plate system
Arranged at the exit end of the last electric field, the more common shape is a louver-like device composed of "["-shaped and "]"-shaped steels. At the same time, it also has the functions of improving airflow distribution and controlling secondary flying, so it also has a significant effect on improving dust removal efficiency.
5. Ash storage system
The function of the ash storage system is to concentrate the dust falling from the electrode and send it to other devices through the ash discharge system. Generally, the ash collecting hopper is in the shape of a quadrangular pyramid or prism. The quadrangular pyramid-shaped ash hopper mostly uses a star-shaped ash discharge valve to discharge ash sequentially and regularly, and the prismatic ash hopper mostly uses a chain conveyor to continuously discharge the ash. There are many accidents in the ash storage system of the electrostatic precipitator, especially the ash hopper that discharges ash regularly. The corona electrode is often grounded because the ash hopper is too full; It will cause the air to leak in and cause secondary flying. In addition, if the capacity of the lower ash discharge device is not enough, it is easy to cause operating failures. If the inclination angle of the ash bucket is too small or the heating and heat preservation of the bucket wall is poor, it will cause poor ash fall or even blockage. Therefore, the design, manufacture and installation of the ash storage system should be paid enough attention to ensure the safe operation of the ash hopper. Some electrostatic precipitators also use ash hopper heating (steam heating, electric heating or hot air heating) devices and detection devices such as material level display and high and low ash level alarms. In order to prevent the half bypass of the airflow, several baffles should be set in the ash hopper.
6. Housing
The shell can be divided into two parts, one part is the frame that bears the entire structural weight of the electrostatic precipitator and external additional loads (the winter snow load must also be considered in the northern region); the other part is used to separate the outside air from the interior of the electrostatic precipitator and is independent. Wall panels that form an ESP environment. Almost all modern electrostatic precipitators use steel shells, and the shells are also made of reinforced concrete or bricks. When capturing high temperature and corrosive flue gas, ceramic tiles or lead plates are used as linings. Generally, the steel consumption of the shell accounts for 1/5~1/3 of the total steel consumption of the precipitator, so it is an important factor affecting the economy of the electrostatic precipitator. The shell should not only have sufficient grace, strength and tightness, but also consider the corrosion resistance and stability under the working environment. Because before and after operation, the components of the electrostatic precipitator will be deformed by heat, so the supports at the lower part of the shell of the electrostatic precipitator cannot all be fixed with the foundation, but only one fixed point, and the other points use various forms of movable supports. to slide it in the indicated direction.
7. Piping system
The pipeline system of the electrostatic precipitator in thermal power plants generally includes three parts: one is the steam heating pipeline. Local heating, generally used for ash hopper heating, the Changle Power Plant in this internship uses serpentine steam heating; the second is the hot air maintenance pipeline, which is heated by an air preheater (heating the air with the waste heat of the flue gas at the tail of the boiler). Parts) to attract hot air, pass through the wall of the hopper directly into the interior of the dust collector, as a heat source for maintenance during shutdown and drying after washing with water, and also continuously supply the electric ceramic shaft, insulating ceramic pillar, and ceramic sleeve during the operation of the dust collector. The parts such as pipes (insulation device between the corona electrode and the shell) are blown with hot air to prevent surface dust; the third is to flush the pipeline with dust accumulation, connect the pipeline to the fire water source, and introduce the water into the electrostatic precipitator when it is stopped. Internally, the electrode is rinsed. This method saves time and effort, has obvious cleaning effect and good working conditions, so this method is generally used, and it is also used for purging with compressed air, but due to poor operating conditions, the purging effect is not good. , has been basically eliminated.

8. Insulation system
Poor insulation will not only affect the uniformity of airflow distribution in the electric field or the normal operation of the electrostatic precipitator due to creepage along the surface caused by the condensation of insulators, but also lead to corrosion of the electrostatic precipitator. It will cause waste of manpower and material resources, so the design and construction of shell insulation can also not be ignored. The insulation material should be made of materials with large thermal resistance, light weight and easy laying, such as rock wool board, slag wool board, glass wool felt , Microporous calcium silicate, vermiculite board, perlite board, etc. The protective plate material of the thermal insulation layer should be corrosion-resistant, anti-aging, and convenient for construction, and the cross-section should be corrugated, such as thin painted steel plates, glass fiber reinforced plastic corrugated plates, etc. The laying of the thermal insulation layer and the protective plate should be done. Continuous, with tight seams to prevent rain leakage.
9. Ladder platform
The ladder platform is the passage leading to all parts of the dust collector, and it is also a workbench for maintenance, inspection and testing and sampling. The platform is required to be wide, unobstructed, durable, and have a certain decorative effect. , save investment. Generally, platforms and escalators should be provided at the part where the manhole door is opened, the lower part of the ash discharger, the location of the corona pole and the dust collector rapping transmission mechanism, the opening of the measuring hole, the vicinity of the high-voltage cable terminal and the top of the electrostatic precipitator.
The above is only a brief description and introduction of the main structure of the conventional electrostatic precipitator, emphasizing the matters that should be paid attention to in the engineering design process of each component.