Abstract
Knowing, that ESP is a "typical fuzzy system" (S. Masuda-S. Hosokawa in Handbook of Electrostatics, chapter 21), including several phenomena and interactions, a new method was created to handle the complexity of ESP modeling. This method is based on fuzzy logic. The experiences industrial electrostatics and control engineering shows, that fuzzy logic is very effective in the handling of complex systems. In the present paper the applicability of the fuzzy logic based ESP modeling is discussed, where classical models can be applied with great difficulty.

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Abstract
The EPRI ESPert program with Automatic mode has been installed by six utilities at six different plants for monitoring and calculating the expected performance of twelve separate electrostatic precipitators. Every 15 seconds the program provides updated calculations of combustion gas composition, actual gas flow rates, calculated emission rates, calculated stack opacities, ash resistivity, total precipitator power per 1000 acfm and other parameters. Predicted opacities for each chamber of the precipitator and total stack opacity are calculated every 15 seconds. This paper presents examples of data acquired and generated by the program and discusses how the program can be used to ensure and improve electrostatic precipitator operation. The use of the program for controlling SO₃ injection rates is also discussed.

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Abstract
Electrostatic precipitators (ESPs) are efficient collectors of fly ash in a wide variety of industrial applications and operating conditions. The optimum performance is achieved, when the collecting plates and discharge electrodes are efficiently cleaned. The cleaning is critical for high resistivity ashes, where the electrical forces between the dust cake and the plate are high.

The deposited ash is usually removed by accelerating collecting plates and discharge electrodes with tumbling hammers. Cleaning is also associated with re-entrainment of ash to the flue gas causing emission peaks, which can be reduced by e.g. off-flow rapping, stepwise rapping or conditioning agents.

In this paper different cleaning technologies and measures to reduce re-entrainment are discussed in connection with experience from commercial ESP installations. The structural dynamics of different collecting electrode systems and rapping modes have also been investigated in the laboratory.

Heavy-duty bottom rapping is the most efficient rapping design for removal of medium to high resistivity dust cakes in ESPs. The rapping is often combined with reduced electrical forces during the cleaning. This can be achieved by an integrated control of energization and rapping.

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Abstract
One of the most commonly used devices for dust removal from industrial flue gases is the electrostatic precipitator (ESP). Dust particles collected in these devices need to be cleaned off the electrodes in adequate intervals to maintain the function of an ESP. The use of hammers rapping against the electrodes to clean them is common practice.

In principle there are many ways to rap the plates with a hammer as there is an almost infinite choice of locations and orientations to install the hammers. Also the hammers can be used for one single element or a set of electrodes. The hammers are typically tumbling hammers that are fixed to a rotating shaft or cylindrical hammers that are lifted by electromagnetic force. Once lifted the hammers usually fall down gravity driven and hit the electrodes via a suitable anvil.

Another aspect is the suspension of the electrodes, which has to be adjusted to the chosen type of rapping system. This interaction between rapping system and the electrode system influences the intensity of the oscillation of the electrodes. The most suitable way to determine the efficiency of a given configuration is to measure the acceleration of the electrodes in those sections where the dust has to be removed. Various types of rapping systems have been investigated to evaluate their efficiency. Acceleration measurements were performed with a frequency analyser. These measurements were done on collecting electrodes as well as on different types of discharge electrodes. Since electrodes installed inside an ESP are hardly accessible most of the measurements took place on a test rig, which allows measurements of full scale electrodes up to dimension of 15m x 5m for one set of electrodes. To validate the data from these tests additional site measurements were carried out.

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