The scrubber has three sections:

Humidification/Pre-scrub Section 

A pipe distribution manifold supplies a "sheet" of water across an air distribution plate at the scrubber entrance. Most of this water is swept through the distribution plate to the open space under the trays. Some of the droplets are carried up into the bottom of the trays which keep them wet and washes off any solids that begin to collect. In this section there is 80-85% humidification/scrubbing of the process gas stream.

Scrubbing Section 

The scrubbing section consists of two or three steps of scrubbing trays. The scrubbing trays have a myriad of small holes that break the gas stream into small air jets that stream through the water on the tray. The water will not fall through the holes because the velocity pressure is higher than the water level in the tray. Many water droplets are thrown into the space above the tray, giving further gas to liquid contact. Water flows from an upper water reservoir over a distribution weir to flood the lower trays, causing the flow to be

uniform across the total surface of the trays. This action is repeated on the lower tray and continues over the lower weir furthest from the inlet and falls into the horizontal recirculation tank.

The air impinging against the surface of the liquid washes the dust from the air. This action also provides a relatively lengthy contact of the gas with surface of the liquid. The gas to liquid contact allows the hydrodynamic scrubber to be adapted to many processes. This unit can be used for gas absorbers, where the gas is soluble in the scrubbing liquids. Where the gas has reached it solubility limit in the liquid, the scrubber can strip the gas from the liquid.

Mist and Droplet Eliminator

 The eliminator section strips off the droplets and mist carried over from the scrubbing trays. As the droplets impinge against the grooves of the insides of the staggered "v" shaped chevrons, the pressure causes the droplets to agglomerate and form a channeled flow back into the horizontal recirculation tank.

Level Controls

The pressure drop across the scrubbing trays (and division baffle in the tank) keep the level on the lower pressure side higher than on the high pressure side. The low pressure side is at the discharge end of the scrubber.

A float control box is located external to the unit on the low pressure end of the scrubber. Reliable float switches in this box regulate the fill valve and circulation pump.

When the system fan and circulation pump are de-energized, the trays and upper reservoirs completely drain. The main sump can be automatically or manually drained to the sewer or other waste water system. There is also a system to provide continuous drain. The latter is used in systems where the dust load is relatively high. The solids liquid ratio should normally be less than ten percent solids.

Chemical Treatments

The scrubber is adaptable to many processes in which alkaline or acids may be added to maintain the proper pH level for a particular gas/liquid contact absorber or stripper application.

A proprietary surfactant is available from EV Air to increase dust collection efficiency even on fumes and mists.

A chemical feed pump and associated control system is available.

Control System

Energize the automatic PLC controlled system. On the optional manual control system, this is accomplished by an "on/off' button.

The water supply valve (WS-1) opens to begin filling the integral recirculation tank.

The water flow continues until the magnetic float switch (FS-2) energizes the circulation pump motor (RP-3).

A time delay relay (TD-4) is activated. This time delay relay is adjustable between 1 and 5 minutes. When the relay times out, the starter (M-5) for the fan motor is energized.

After the fan is operating another float switch (FS-6) regulates the final operating depth of the scrubber. It opens and closes the (WS-1) supply valve to maintain a constant level.

At this time, the chemical additive pump control system is activated. The pump (CP-7) begins to dispense chemical into    ( the scrubber tank. The duration of the operation of this pump is regulated by a timing relay (TD-8), which shuts the pump off after a preset interval from 1 to 10 minutes. An optional circuit and probe will allow the pump circuit to be energized whenever the concentration reaches a minimum level.

Semiautomatic skimming control (if provided) overrides the high level float

control (FS-6) at preset intervals for an adjustable time period of 1 to 5 minutes. This allows the water level to rise above the end weir. The water overflow and air movement skims off the floating material. At the end of the skim/purge cycle, the high level float control returns to its regular function.

Shutdown

De-energize the main control switch. (The "off' button on the system control package, if on manual.) Pumps, fans, and valves are stopped or closed in a programmed sequence.

Tank can be drained either manually or with an optional solenoid controlled valve (DP-8). Frequency of draining the tank is dependent on the dust load and other process considerations. If manually operated, the valve needs to be closed before the system is restarted.

If water supply fails and levels fall in tank, the FS-2 float switch will close, shutting off the circulation pump motor (RP-3).