Flakt Aktiebolag

Sigvard Matts

Alf G Gustafsson

A method and device for varying a d.c. voltage connected to an electrostatic dust separator so as to render more effective, in return for a low consumption of energy, the collection of dust on an electrode or electrodes incorporated in the dust separator. The d.c. voltage is set to a first level (basic level), said level having superimposed on it a number, in each case two or more, of voltage pulses forming a pulse group, with the consecutive pulse groups being separated from each other in a time sequence and supplied to electrodes incorporated in the dust separator. A pulse generating device is so arranged as to generate a number of pulses making up a pulse group, whereby the first pulse (21) in said pulse group is selected so as to exhibit an amplitude and/or a duration and/or a form such that, when the pulse is supplied to the dust separator, it will not cause flash-over but will produce an increase in the tendency to flash-over (20') of the dust separator, in conjunction with which the immediately following pulse (22) in the pulse group is selected so as to exhibit an amplitude and/or a duration and/or a form such that, when the pulse is supplied to the dust separator, it will not cause flash-over in spite of the increased tendency to flash-over (20') caused by the preceding pulse, and so on.

Method and device for varying a d.c. voltage connected to an

A system and method for controlling energy input to a series of electrostatic dust separator devices having a common gas inlet and a common gas outlet. A detector unit is disposed in the gas outlet to detect the dust concentration or evaluate the actual dust loss in the exhausted gas. Energy control circuitry is coupled with each separator device to control the energy input to each separator device. The control circuitry is actuated by an actuating device to first change and then restore the energy input to each of the separator devices in a selected sequence to thereby change and restore the dust concentration in the exhausted gas. Computation circuitry is coupled with the detector unit to compute the change in dust concentration resulting from a certain change in energy input to each of the separator devices in the sequence. Calculator circuitry selects the separator devices producing a desired change in the dust concentration in response to the certain change in energy input to each of the separator devices. The actuating device is coupled with the calculator circuitry and the control circuitry of each separator device to change the energy input to at least one selected separator device producing the desired change in dust concentration.

System and method for controlling energization of electrodes in

A control device for an electrostatic dust separator (10,11) intended to control in relation to the recorded level of direct current (104) and direct current voltage (102) in the dust separator and with the help of the supply voltage (6a) passes through the zero point the switching in and/or out of the rectifiers (8, 8a) wired into the power supply lead (6a) to the dust separator, usually in the form of two thryistors. The recorded value for the current (104) and the recorded value for the voltage (102) together with the information in respect of the passage through zero of the supply voltage (100) are connected directly via conversion circuits (25, 26) to a data processing unit (112). This (112) is so arranged that in relation to the value (102, 104) of the actual direct current and direct current voltage in the dust separator and with reference to the passages through zero (100) it will on the one hand calculate a specific time interval for the switching in and/or switching out of the rectifier (8) from the power supply and on the other hand generate switching-in and switching-out pulses (112a, 112b). These switching-in and switching-out pulses are fed directly, via adapter circuits, from the data processing unit.

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Vaxjo, Sweden

Sigvard Matts