United Air Specialists, Inc.

William A Cheney

Wendell P Spurgin

Robert S Wilks

Victor L Sellers

John T Grady, Jr

Kevin Lefler

An improved electrostatic precipitator system is provided for use in high-grease atmospheres in which the grease is electrically conductive. The precipitator includes high-voltage insulators that are both located in areas unlikely to accumulate electrically-conductive grease and that, in themselves, can operate in a high-voltage system without tracking, even when a certain amount of conductive grease has accumulated on the insulators' surfaces. In a multi-cell precipitator system, a high-voltage insulator is provided as part of a cell-to-cell assembly that receives high-voltage electricity on one side of its insulator, and conducts that electricity to its opposite side, and is placed in a specially-shaped cut-out in the bulkhead between the cell chambers, in which the cut-out is shaped so as to minimize the amount of grease that may accumulate upon the cell-to-cell assembly's insulators. The electrostatic precipitator also includes a high-voltage electrical power supply that has special current limiting features and time delay functions that allow it to operate during relatively brief time intervals when a high-humidity atmosphere exists along with the electrically-conductive grease particulate. The electrostatic precipitator also includes electrical door interlocks using safety limit switches to detect whether or not any of the doors have been opened and which shut down the high voltage power of the system in the event of an untimely opening of one of the doors.

Electrostatic precipitator that operates in conductive grease atmosphere

An electrostatic air cleaner is disclosed for use in removing particulate matter from moving streams of air. A high voltage ionizer is used as a corona source to ionize the particulate matter as it approaches the air filter portion of the electrostatic air cleaner. The air filter uses reticulated polyether foam filter media for collecting the particulate matter, and the filter media is non-deliquescent, thus preventing the high-voltage electric field from being dissipated by imbedded water vapor, which is the cause of filter inefficiency in the prior art. In one embodiment, the air filter uses strips of conductive material raised to a very high DC voltage interleaved between strips of conductive material held to ground potential, and these strips are oriented so as to be parallel to the direction of the air flow through the air filter's foam filter media, thereby creating an electric field that is perpendicular to the direction of air flow. In a further alternative construction, a charge accumulator is located adjacent to or within the ionizer to collect ions that migrate from the ionizer's electrodes to the collecting member of the charge accumulator. The charge accumulator is raised to a very high DC voltage and is electrically connected to the high-voltage conductive strips of the air filter, thereby eliminating the need for a high-voltage DC power supply to charge these conductive strips directly.

Apparatus for electrostatically cleaning particulates from air

An electrostatic air cleaner is disclosed along with a method for removing particulate matter from moving streams of air. A high voltage ionizer is used as a corona source to ionize the particulate matter as it approaches the air filter portion of the electrostatic air cleaner. The air filter uses a pair of reticulated polyether foam filters for collecting the particulate matter. The foam filters are separated by a thin, grid-like layer of semiconductive material (carbon-impregnated polycarbonate) which is raised to a very high DC voltage. The foam filters are also surrounded by thin, grid-like layers of electrically conductive material which are held at ground potential, thus creating a high-voltage electric field through each of the foam filters. The polyether foam filter media is non-deliquescent, thus preventing the high-voltage electric field from being dissipated by such imbedded water vapor, which is the cause of filter inefficiency in the prior art. The electrostatic air cleaner of the present invention has such high initial efficiency that it does not require the addition of any particulate matter to its surfaces to achieve its nominal efficiency when first put into use. The air filter can be constructed in a relatively thin, rectangular shape, or in a cylindrical cartridge for use with industrial dust collecting systems. Both shapes lend themselves for ease of installation and removal within air handling systems.

Method and apparatus for electrostatically cleaning particulates from air

A conventional HEPA (high efficiency particulate air) filter is provided with a ionizer at its air inlet face to enhance its efficiency. The filter comprises a non-conductive fibrous filter medium sheet formed in a zig-zag or accordian fold. Within each fold of the filter medium is there located a conductive spacer so that the accordian folds are supported and substantially evenly spaced throughout the filter. By virtue of the accordian fold of the filter medium sheet, a series of spacers, forming a first set thereof, each has one of its longitudinal edges exposed at the air inlet face of the filter and the other of its longitudinal edges covered at the air discharge face of the filter. The remaining spacers constitute a second set thereof, each having one of its longitudinal edges exposed at the air discharge face of the filter and the other of its longitudinal edges covered at the air inlet face of the filter. The spacers of the first and second sets alternate, one adjacent the other. The ionizer comprises a plurality of wire-like electrodes and grounded plate-like electrodes arranged alternately and in parallel spaced relationship in a plane perpendicular to the spacers and are positively charged by connection to a high voltage, low current source. The ionizer electrodes are located within charging range of the first set of spacers which are charged by ion flow from the corona of the ionizing electrodes. To create a field between the first set of spacers and the second set of spacers, the spacers of the second set are connected together and to ground. In another embodiment the ionizer is located remotely with respect to one or more HEPA filters and functions to charge the particulate material. A single wire-like electrode is located at each HEPA filter to charge one of its first and second sets of spacers, the other of its first and second sets of spacers being connected to ground.

Electrostatically enhanced HEPA filter

A method and apparatus for treating electrically charged airborne particles to reduce deposition of the particles on walls and other exposed surfaces in an enclosed area. Air containing positively charged particles exhausted from a first group of electrostatic precipitators is admixed with air containing negatively charged particles exhausted from a second group of electrostatic precipitators, the mixed air containing oppositely charged particles having less tendency to become deposited on walls and other surfaces in the enclosed area.

Method and apparatus for treating electrically charged airborne particles

The means and method for the cleaning and self-cleaning of an electrostatic precipitator is especially suited for adaptation to an electronic air cleaner comprised of an ionizer unit and a collecting cell unit adapted to be included in tandem within a suitable cabinet; means to bring air to be cleaned through these units are also provided, and these may or may not be an integral part of the cleaner. The ionizer unit may include support members for a plurality of ground plates between which are located ionizing wires which normally carry a low current but high voltage, preferably in the neighborhood of 10,000 to 14,000 volts. (Some electronic air cleaners, however, use voltages in the 5,000 to 9,000 volts range. This invention will also work effectively with them.) The collecting cell unit includes support members for a plurality of grounded collecting plates and there are a plurality of charged collecting plates suitably supported within the collecting cell unit and interleaved among the grounded collecting plates, the grounded plates and charged plates being out of electrical contact with one another. The charged plates normally carry a low current, high voltage charge in the neighborhood of 5,000 to 7,000 volts. The means and method of this invention, however, will function satisfactorily with all known voltage ranges normally applied to the ionizer and collecting cell in a 2-stage precipitator. Hopper means are located beneath the ionizer and collecting cell in position to receive precipitated contaminants which are removed from the air stream passing therethrough and which are intially collected on the various plates.

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Cincinnati, OH, United States of America

William A Cheney