Pulse Jet Bag Filter

Mechanical Shakers :

In mechanical shakers bag houses, tubular filter bags are fastened onto a cell plate at the bottom of the bag house and suspended from horizontal  beams at the top. Dirty gas enters the bottom of the bag house and passes through the filter, bags and the dust collects on the inside surface of the bags.

Cleaning by a mechanical shakers, bag house is accomplished by shaking the top horizontal bar from which the bags are suspended . Vibration produced by a motor driven shaft and can creates waves in the Bags to shake off the dust cake.

Reverse Air : 

In reverse-air bag house, the bags are fastened onto a cell plate at the bottom of the bag house and suspended from an adjustable hanger frame at the top. Dirty gas flow normally enters the bag house and passes through the bag from the inside, and the dust collects on the inside of the bags.

Pulse Jet :

In reverse pulse jet bag house, individual bags are supported by a metal cage (Filter Cage) which is fastened onto a cell plate at the top of the bag house. Dirty gas enters from the bottom of the bag house and flows from outside to inside the bags. The metal cage prevents collapse of the bag.

A short burst of compressed air injected through a common manifold over a row of bags. The compressed air is accelerated by a venture nozzle mounted at the reverse-jet bag house top of the bag. Since the duration of the compressed air burst in short (about 0.1 sec) it acts as a rapidly moving air bubble, travelling through the entire length of the bag and causing the bag surfaces to flex. This flexing of the bags breaks the dust cake, and the dislodge dust falls into a storage Hopper. Dust discharge through Air Lock Rotary Valve or by a sliding gate.

Bag House :

A bag house, also known as a Bag House Filter, Bag Filter or Fabric Bag Filter is an air pollution control device and dust collector that removes particulates or gas released from Industrial  commercial processes out of the air. Power Plants, Steel Mills, Pharmaceutical Producers, Food Product manufacturers, Chemical Plants and other industrial companies often use bag houses to control the emission of air pollutants. Bag houses came into widespread use in the late 1970’s after the invention of high-temperature resistance fabrics (for use in the filter media) capable of withstanding temperatures over 350 ⁰F (177 ⁰ C).

Unlike electrostatic precipitators, where performance may vary significantly depending on process and electrical conditions functioning of bag houses typically have a particulate collection efficiency of 99% or better. Even when particles size is very small.

Operation :

Most bag houses use long, cylindrical bags or tubes made of woven /non-woven or felted fabric as a filter medium. For applications where there is relatively low dust loading and gas temperature are 250 ⁰F (121 ⁰C) or less, pleated non- woven cartridges are sometimes used as filtering media instead of bags. Dust laden gas or air enters the bag house through hoppers and is directed into the bag house compartment. The gas is drawn through the bags, either on the inside or the outside depending on cleaning method, and a layer of dust accumulates on the filter media surface until air can no longer move through it. When a sufficient pressure drop occurs, the cleaning process from the stream with a 50% efficiency. Particles larger than the cut point will be removed with a greater efficiency, and smaller particles with a lower efficiency as they separate with more difficulty or can be subject to re-entertainment when the air vortex reverses direction to move in direction of the outlet.

Airflow diagram for Aerodyne Cyclone in standard vertical position. Secondary air flow is injected to reduce wall abrasion.

Airflow  diagram for Aerodyne Cyclone in horizontal position,  an alternate design. Secondary air flow is injected to reduce wall abrasion and to help move collected particulates to hopper for extraction.

An alternative cyclone design uses a secondary air flow within the cyclone to keep the collected particles from striking , the walls to protect them from abrasion. The primary air flow containing the particulates enters from the bottom of the cyclone and is forced into spiral relation by stationary spinner vanes. The secondary air flow enters from the top of the cyclone and moves downward towards the bottom, intercepting the particulate from the primary air. The secondary air flow also allows the collector to optionally be mounted horizontally, because it pushes the particulate towards the collection area and does not rely solely on gravity to perform this function.