ALmix Reverse Air Rotary Baghouse | Overview

The Reverse Air Rotary Baghouse is a continuous-duty, modular collector with bag-style filters. The unit is used to collect airborne dust and particulate in the asphalt plant’s exhaust gasses. The simple, reliable design efficiently handles both low and high volumes of dust and provides plant operators with value through the ability to return dust and fines to the mix. Continuous duty means the filters are cleaned in sequence, one set at a time without turning the unit off. The filter bags encompass a large filter area in a small compact housing thus keeping the air velocity through the bag to a very low level when compared to traditional pulse jet baghouses.

A low dryer velocity coupled with a low air-to-cloth ratio results in high performance. These principles are stictly adhered to at ALmix. Dryer velocities are held below 1,000 FPM and air-to-cloth ratios are held below 5-1. Primary collectors are not required. Baghouses feature a return dust system that includes a variable speed waste dust auger to allow adjustment of fines being returned to the mixing drum. Ductwork connecting the dryer to the baghouse allows room for misalignment and is assembled using chain binders instead of bolts.

ALmix offers both portable and relocatable (skid-mounted) baghouse styles. (pictured to the right)

ALmix Reverse Air Rotary Baghouse | Cleaning Process

ALmix reverse-air baghouses are compartmentalized to allow for continuous operation. Before a cleaning cycle begins, filtration is stopped in only the compartment to be cleaned, which occurs by injecting clean air into the dust collector in a reverse direction, which in turn pressurizes the compartment. The pressure makes the bags collapse partially, causing the caked on dust to crack from the filter bags and fall into the hopper below. At the end of the cleaning cycle, reverse airflow is discontinued, and the compartment is returned to the main stream.

The cleaning nozzle drive and sequence mechanism consists of a right angle gear motor with rotating eccentric drive shaft that engages a central sprocket.  The mechanism moves the cleaning nozzle from row to row quickly but allows the nozzle to pause momentarily at each row.  The cleaning mechanism automatically starts cleaning according to a preset time which is adjustable by the plant operator.  After the nozzle completes a full cycle and returns to its parked position, a sensor cuts off power to the cleaning mechanism gear motor.  The baghouse requires no compressed air for cleaning.

ALmix Reverse Air Rotary Baghouse | Features

Almix primary knockout box and ductwork to baghouse

Almix primary knockout box and ductwork to baghouse

KNOCKOUT BOX AND DUCTWORK: The primary knockout box style collector is mounted over the dryer frame to collector heavy fines in the exhaust gas stream.  The fines are dropped into a sloped hopper and trickle valve where the fines will be discharged into the Drum Mixer Rap Collar.  Capturing these larger particles lessens the wear on the bags and increases bag efficiency.  The ductwork between the drum mixer and baghouse is constructed from 3/16" steel plate. Ductwork connecting the baghouse to the exhaust fan is designed to provide minimum pressure drop.

DUST/FINES COLLECTION: The baghouse hopper section contains a screw conveyor for collecting the fine dust released from the baghouse cleaning process. Connected to the collecting screw is an inclined screw conveyor which returns the collected dust to the mixing section of the drum mixer.

Configurations including vane feeders, dust silos and other components for monitoring and storing collected dust and fines are available.

ALmix baghouse exhauster and motor

ALmix baghouse exhauster and motor

BAGHOUSE EXAUSTER: The pollution control system is powered by a high efficiency, low energy, backward inclined exhaust fan powered by a motor through a fully digital AC flux vector drive.  This frequency drive control eliminates the need for a soft starter and a mechanical damper while also eliminating voltage drops on fan startup. Test ports are installed in the stack and a platform accessible from the baghouse top section is supplied. Our optional direct drive configuration eliminates the need for sheaves and multiple belts and belt guards.

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