Abstract
It is well-known, that dust properties have a strong influence on the process of the precipitation. Some of the main relationships between the precipitation efficiency and the parameters of dust, like specific resistance, permittivity, particle size etc. have also been published [1].

There are several uncertainties in the determination of these parameters. Some parameters can not be properly determined, some properties cannot be measured continuously, and some of them are changing during the operation of ESP, etc. Because of the uncertainty of these factors the reliability of ESP models can decrease with decreasing accuracy of the input data.

The most important aim of our investigations was to determine the effect of the variation of the dust parameters on the precipitation. The degrees of these dependencies have been investigated and presented  in  the  paper.  Based  on  the  new  results,  it  is  possible  to  estimate  what  accuracy  is necessary in case of different parameters to obtain reliable ESP models.

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Abstract
Voltage-current characteristics are a basic tool to analyse the operational conditions of an electrostatic precipitator, and to detect the onset of Back-corona, that strongly affects the collection performances. In this investigation, a laboratory set-up has been arranged, with a classical ESP wireplate configuration; both static and dynamic voltage-current characteristics have been measured and analysed with different geometries, dust characteristics, and layer thickness. Similar results have been also obtained in an industrial ESP, and compared with the laboratory results.

In the laboratory ESP, the static voltage-current characteristics and the collection efficiency have been measured as functions of time; with high resistivity dust, back-corona takes place as layer thickness increase, with a decrease of the efficiency and a sharp raise of the current. The effect of electrode type and powder resistivity has been analysed.

With varying applied voltages, the dynamic voltage-current characteristics show an hysteresis cycle, the recorded values depending on the slope of the applied waveform. The shape of the dynamic characteristics changes significantly with the onset of back-corona.

A self-consistent numerical model has been applied to simulate static and dynamic voltage-current characteristics in absence of back-corona. These simulations allowed to analyse the retarding
effects of the different physical process (capacitive charging, ion drift, space charge movements), and to estimate the corresponding time constants. Finally, the dynamic effects of back-corona have been
analysed.

Abstract
In this paper, the characteristics of the magnet enhancement corona discharges and their function for charging particles are introduced. The experimental results demonstrated that the magnet field could obviously increase the discharge current and enhance the particle agglomeration in corona discharges. The deflection of free electrons between the discharge and collection electrodes was measured. Therefore we can deduce that both the energy of free electrons and the concentration of free electrons and ions are increased in the magnet enhancement corona discharges. Comparing with the uniform magnet field, the uneven magnet field formed by the permanent magnet nearby the discharge electrodes can more effectively intensify corona discharges. We developed an aerosol charger of the magnet enhancement corona discharges with permanent magnet. The charging current was increased by 25% in a magnet field of 0.02T.

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Abstract
Emission excursions are sometimes explained by weird and wonderful theories and speculations about changes in ash chemistry and a whole host of other often complex reasons.    In many instances when this happens one finds that surprisingly often the “basics” have been overlooked. In extreme cases this could be something as obvious as a field being out of service.   This Paper addresses the basics.

Matimba Power Station is situated in an environmentally pristine area in the northern part of South Africa, 13 km west of Lephalale in the Limpopo Province approximately 75 km from the Botswana border.   This area is known for its “eco-tourism” and local environmentally conscious communities do not easily accept this Power Station and other industries associated with the abundant coal reserves found in the area.   The long-suffering ESP Systems Engineer often has to bear the brunt of these conflicts of interests. 

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Abstract
The two 4-fields, 230 m² flow area, magnetic hammer top rapping precipitators of a 300MW unitin Zhangjiakou Power Plant encountered dust accumulation and clogging difficulties, especially in third and fourth fields. By mounting acoustic horns of SQ-75 type, produced by Liaoning zhongxin Automatic Instruments Company, for one channel, four fields on the top, in the sidewalk between electric fields and in the hopper, dust scale up and accumulation problems were eliminated. Operation voltage and current were increased by 6% and 28% respectively. Working principle and detailed description are given. 

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