KleanAire Technology, LLC.

THE TECHNOLOGY

A method for improving the removal of particulate matter, heavy metals and acidic gases from waste emissions streams through continuous control of independent filtering chambers. Each chamber provides individual control over the separate processes of cleaning, pre-coating with sorbent material and filtering. This process allows the operator to optimize emissions collection efficiency, costs and prevent fugitive emissions.

INHERENT FLAWS IN CURRENT DRY SCRUBBING
The Dry Flue Gas Scrubber (DFGS) technology is acknowledged as the most widely used air pollution control scrubbing process. Many modifications have been made to enhance the original baghouse design and efficiency however these modifications have been unable to resolve a significant inefficiency in the technology. This inefficiency is due to the "spikes" in emissions which occur during baghouse cleaning cycles. These spikes are shown in the figure below.

FIGURE 1. Mercury concentrations and baghouse pressure drop during extended Darco FGD injection tests. (Ref: “Full-scale Evaluation of Mercury Control at Great River Energy’s Stanton Generating Station Using Injected Sorbents and a Spray Dryer/Baghouse”, 2002 Air Quality III Conference, Session A3b, R. Chang et al)

Most improvements have sought to use semi-dry technology, dry sorbent injectors, electrostatic precipitators, or alkaline liquid sprays installed up-stream of the baghouse to control acid emissions and improve filter coating which is known to capture particles in the one micron range within the flue gas stream. Such pretreatment has been able to decrease the load on the baghouse filters and improve the overall efficiency. These elaborate pretreatment systems have been able to achieve up to 95% (ninety five percent) efficiency for acid removal, and improvements in filter media types have reportedly improved particulate matter (PM) recovery as high as 99.9% (ninety nine point nine percent) efficiency.

These advancements have improved the dry scrubbing process, but have been unable to address an inherent flaw in the design of the baghouse filtration process which prohibits the DFGS process from achieving the continuous steady-state operation that is found in wet scrubbing technology.

THE SPIKE-FREE TECHNOLOGY
To remove the cleaning "spikes" KleanAire Technology uses a method and device called The Emissions Terminator™. The device employs long-known methods difficult to implement without pretreatment methods such as electrostatic precipitators (ESPs) or pre-filter systems adding to cost, The KleanAire Technology process advances the art of air pollution control through the implementation of a clean atmosphere for coating without a pre-treatment system. The Terminator™ makes the following improvements possible:

A thin coating can now be applied to the surface of any filter media under selection, which is known to improve filter capture rates of PM to high levels.
The efficient use of sodium bicarbonate as a reagent sorbent alkaline proven in the incineration arena to be highly effective in PM, acids, metals, voc and PM on levels that rival active carbon at less cost.
A clean-air precoating application system which is able to apply selective sorbent upon individual filter sections for the development of a sorbent coating without allowing polluted gases to pass through, thereby eliminating cleaning spikes.
Definitive air flow control through individual filter segments which are able to lower air flow rates during precoating and preventing:
- Injected sorbent particles from being drawn through the fabric of the woven filter media fabric by high air velocities after cleaning.
- Filter cloth wear from abrasion between the filter media and the support cage resulting in longer filter life.
Having multiple sorbent injection points provides the capability to,
- Apply sodium bicarbonate or activated carbon as a precoat to reduce cost and increase efficiency.
- Apply powered limestone as body feed sorbent supplied during flue gas processing.
- Apply a 1~4 mil thickness of precoat outside of hot, polluted flue gas stream known to protect filter media from heat and deterioration from acids.

Termination Chambers
A simplified version of the The Emissions Terminator™ device is diagramed in the figure below. As the minimum number of chambers required for processing is three.

FIGURE 2. The Emissions Terminator™ (u.s. patent no. 6,451,091 1B) chambered pollution control system able to simultaneously clean, precoat, and operate all cycles without breeching, fugitive emission cleaning spikes.

Figure 2. illustrates the three phases of operation of the filter baghouse system. Each chamber is bracketed by inlet and outlet dampers controlled by a Process Logic Controller (PLC) that monitors the pressure within each chamber and stage process to channel treated and untreated flue gas streams through the baghouse filter chambers. The logic of the controller maintains a delicate airflow balance that permits the introduction of untreated flue gas into a clean chamber without breeching the pre-coating surface after the filter has been cleaned.

FIGURE 3. Terminator cleaning cycle upper dampers close to seal discharge side of filter during cleaning and purging. Chamber enclosures permits filter segment to be isolated from adjacent filters to prevent carry over collection and channels collected fly-ash and spent sorbent to collection hopper below.

FIGURE 4. Precoating Cycle begins when lower dampers are closed and upperdampers are opened then a selected sorbent e.g., (sodium bicarbonate, limestone, or activated carbon) is used depending upon the practical emissions processing requirements for the application.

FIGURE 5. Filtering Cycle begins once a precoat layer has been established upon the filter media and a pressure drop is developed across the coated filter media, then the lower damper doors are opened and untreated flue gas is introduced into the filter chamber and remains so until a higher pressure drop setting is achieved and the filter goes into a cleaning mode.

Click here to download an interactive simulation of The Emissions Terminator™