Problems in the operation of electric tar capturers and solutions!
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Experience from system operation is for reference only! (A few measures were discussed in #6; please, fellow users, provide additional suggestions.) 1. Solutions to the tar clogging problem: During the operation of the electrostatic tar catcher, the tar that reaches the inner wall of the sedimentation electrode flows down along the wall. When the tar is highly fluid, it flows to the bottom and is then discharged through the liquid seal tank and the return liquid main pipe. If the fluidity of the tar captured by the electrostatic tar catcher is very poor, even with normal flushing of the ammonia water pipe using inclined plates, internal discharge will occur after about a week, along with abnormal noises. When this occurs, it is necessary to carry out a flushing of the electrostatic tar catcher: the outlet gas valve is closed, and hot ammonia water is sprayed from the top of the electrostatic tar catcher to wash the honeycomb structure and the gas distribution plate. Each flushing process results in the removal of a large amount of tar; such a flushing operation takes about 1 hour. After about 2 hours of natural cooling, the gas outlet valve is opened and the device can resume normal operation. For each shift, it is also necessary to carry out flushing of the liquid seal tank; by using a downhole camera, it is possible to check whether the pipes are unobstructed and to assess the accumulation of tar inside them. When tar blockage occurs at the bottom of the electrostatic precipitator or inside its tubes, the following two methods can be used to resolve it. First, close the outlet valve of the lower flushing pipe; hot ammonia water is then introduced into the electrostatic precipitator through the inclined plate flushing pipe, and it is discharged into the liquid seal tank via the upper flushing pipe. This method allows for effective heating and flushing of the tar accumulated at the bottom of the electrostatic precipitator, while also enabling a clear assessment of the condition of the upper and lower flushing pipes. It is also an effective way to deal with blockages in these flushing pipes. Second, close the outlet valve of the upper flushing pipe; hot ammonia water is fed into the upper flushing pipe to directly flush the interior of the electrostatic tar catcher, and then flows into the liquid seal tank through the lower flushing pipe. When a large amount of tar accumulates in the liquid seal tank, close the valves of the upper and lower flushing pipes to break the connection with the electrostatic tar collector, and flush the liquid seal tank separately using hot ammonia water. 2 Problems related to zero insulation and countermeasures: When issues arise in electric tar catchers, the first step is to perform a pressure retention test using nitrogen, and blind flanges are installed at the gas inlet and outlet to isolate the system. After isolation, manholes are opened for inspection; once the problems have been resolved, the area is purged with nitrogen. Once the purification is complete, the blind flanges are removed and the valves are opened to resume operation. The time required for each such treatment is generally 16 hours, but it can take up to 48 hours in cases where things don’t go smoothly. This process is time-consuming and labor-intensive, and safety cannot be fully guaranteed. If the valve does not close properly, an increase in the oxygen content in the gas can occur when removing or installing blind flanges. After modifying the corona wire, it is easier to determine when a wire has broken during each treatment, and the processing is also very fast. Later, only pressure retention tests were conducted; as long as these tests passed, the manholes were removed even if the replacement process was not thorough. When removing the manholes, it was essential to follow the sequence of opening the upper manhole first and then the lower one, in order to prevent a chimney effect from occurring within the electrostatic precipitator. This approach proved effective, allowed for quick and safe handling, and also **saved on maintenance costs**. The following introduces several methods for dealing with zero insulation. (1) Corona electrode wire breakage. When the nitrogen heating system is functioning properly, the problem of corona wire breakage still occurs frequently. Φ4mm stainless steel wire ropes can be used as a substitute for nickel-chromium wires, which significantly improves the natural verticality of the corona electrode and effectively corrects the deviations caused by the non-vertical alignment of nickel-chromium wires. However, in 2008, there were still 6 occurrences of corona electrode wire breaks. There are two scenarios for broken corona electrodes. In one case, after opening the manhole, it is possible to see a weight or a section of electrode wire with a hook on the gas distribution plate; by determining the location of these elements, it is possible to accurately locate the honeycomb structure. Then, using a long-tube mask, one can reach inside through the upper manhole and use a hook to pull out the broken electrode wire hanging from the hanger. A new electrode wire is then installed, and once the insulation level is confirmed to be satisfactory, the manhole can be sealed again. In another case, after opening the manhole, no weight or wire with a hook could be found; the insulation inside the electrostatic precipitator was found to be satisfactory upon measurement, yet the secondary voltage still fluctuated severely when the electrostatic precipitator was turned on. Upon close inspection, it was found that after the corona wire broke, the weight and the broken wire with the hook did not fall off, but were trapped by the lower fixing ring; as a result, it was difficult to detect the broken wire. The upper pole wire, being suspended, remains in a vertical position when no electricity is applied, so it does not touch the walls and thus maintains good insulation; however, once electricity is applied, it comes into contact with the walls of the honeycomb structure, resulting in grounding. (2) Breakdown of the insulating sleeve. Although a zero insulation condition or direct grounding in electric tar collectors is mostly caused by broken corona electrodes, it can also be resulting from damaged wall-mounted bushings for electrical connections. (3) The insulator has low insulation. It is mainly due to the effect of temperature; raising the temperature will solve this problem. This post was last edited by ryn on 2009-1-7 16:14]
Our electric precipitator often experiences fluctuations in voltage and current; sometimes the voltage even fails to rise. Please advise! Thank you! ! !
After the corona electrode in our factory broke, there were no replacement parts available, so we simply removed the broken part and used the remaining wire; it worked for two years. Now too many of these electrodes have broken, and we have to consider replacing them again. As mentioned by the original poster, all the new ones also break – the quality of these corona electrodes is really poor
Is there no better way to remove tar from coke oven gas? Electrostatic collection is an option, but it has problems and isn’t very effective. The original poster, give some ideas.
In the daily maintenance of electrostatic precipitators, maintaining an appropriate temperature in the insulation box jacket and performing regular cleaning are two key factors for its stable operation.
I think it might be appropriate to consider this from the following aspects; everyone can discuss it. 1. Water seals should be installed as much as possible at the inlet and outlet to ensure safe production; even if blind flanges are needed, they should be placed after the water seals, which is even safer. 2. Adding a collar at the distance between the corona wire and the outlet at the bottom of the honeycomb structure can reduce the risk of the corona wire coming into temporary contact with the precipitator electrode due to fluctuations in airflow, thereby preventing damage to the wire. Additionally, installing a stainless steel sleeve with appropriate inner diameter, wall thickness, and length below the corona wire and above the suspension ring helps to protect the corona wire and extend its service life. 3. Another electrostatic tar catcher can be installed, allowing several of them to operate in parallel. 4. To prevent accidents such as insulation breakdown caused by moisture, it is crucial to use nitrogen to protect the insulators in the insulation box. Electric heating or steam heating can be employed; the temperature of the nitrogen outlet and the amount of nitrogen used are determined based on the actual conditions of the factory ； In plants without nitrogen, purified coke oven gas can be heated and used as a shielding gas (this is generally not recommended as it poses safety risks). I’m not sure if I have explained or answered the questions posed by those above; I hope experts can give me some guidance! This post was last edited by ryn on 2009-4-1 11:19]
The tar collected on the sedimentation plates can be heated with steam first and then rinsed with ammonia water, which will yield better results; a steam coil can be installed at the bottom of the equipment to increase heat and thus improve its fluidity. There are mainly two types of failures in electric capture ； 1. If the corona electrode wire is fractured, purchasing products from reputable manufacturers and using single-strand, soft manganese-enhanced stainless steel wire can successfully resolve this issue. 2. The insulating porcelain insulators may crack or become covered with moisture and tar; this phenomenon is caused by excessively low temperatures in the insulation boxes. Most existing electric collectors use steam jackets for insulation, but the temperatures within these insulation boxes can vary significantly. A PID temperature control valve can be installed in front of the steam coil to keep these temperatures stable at 100 degrees, thereby resolving the issue. I share this information with you all; I hope experts can offer some guidance
Right now, apart from using an electric degreaser, I don’t know about anything else :( ......
Common faults in electric precipitators include broken corona wires and cracked ceramic cylinders. The reason for broken corona wires is that the interior of the electric precipitator is dirty, especially at the bottom of the corona wires, where there is a lot of tar adhered. Due to the surface tension of the liquid, this tar forms local sharp points; the electric field strength increases near these points, leading to frequent discharges and eventual breakdown as a result. Furthermore, the upper and lower hangers used to control the position of the corona wire are severely deformed, making it difficult to adjust the position of the corona wire; as a result, its installation exceeds the allowable tolerances, which reduces the distance between the positive and negative poles and leads to discharge breakdown. The reason for the cracking of the porcelain cylinder is the low temperature inside the insulation box, as well as the humidity there; these conditions lead to the formation of liquid droplets on the walls of the porcelain cylinder, which in turn cause creeping arcs and result in the cracking of the cylinder.
There are mainly two types of failures in electric capture； 1. If the corona electrode wire is fractured, purchasing products from reputable manufacturers and using single-strand, soft manganese-enhanced stainless steel wire can successfully resolve this issue. 2. The insulating porcelain insulators crack or become covered with moisture and tar; this phenomenon is caused by excessively low temperatures in the insulating chambers. Most current electric precipitators use steam jackets for insulation, but the temperatures within these insulating chambers often vary significantly. By installing PID temperature control valves in front of the steam coils, it is possible to keep these temperatures stable at 100 degrees, thereby resolving the issue. Common faults in electric precipitators include broken corona wires and cracked ceramic cylinders. The reason for broken corona wires is that the interior of the electric precipitator is dirty, especially at the bottom of the corona wires, where there is a lot of tar adhered. Due to the surface tension of the liquid, this tar forms local sharp points; the electric field strength increases near these points, leading to frequent discharges and eventual breakdown as a result. Furthermore, the upper and lower hangers used to control the position of the corona wire are severely deformed, making it difficult to adjust the position of the corona wire; as a result, its installation exceeds the allowable tolerances, which reduces the distance between the positive and negative poles and leads to discharge breakdown. The reason for the cracking of the porcelain cylinder is the low temperature inside the insulation box, as well as the humidity there; these conditions lead to the formation of liquid droplets on the walls of the porcelain cylinder, which in turn cause creeping arcs and result in the cracking of the cylinder.
2# Knight’s Tears: Can’t increase the voltage? Will it stay like this after it goes into operation? How often do you use steam to purge or hot ammonia water to clean your electrostatic precipitators? Based on what you said, the interior seems to be quite dirty, so it’s best to use hot ammonia water for cleaning.