Have you ever driven by a concrete batch plant while a cement tanker is blowing off and see that unmistakable gray plume of dust billowing out of the top of the silos or bins? Ever wait for what seems like forever for your cement batcher to either weigh up or discharge a load?
Aside from risking unwarranted attention that could lead to an unwelcome visit from the Federales, both of these issues are a huge waste of time and money. Think about the hundreds and possibly thousands of pounds of cement that are blown off into the atmosphere over time. Last I checked, cement isn’t free, in fact it’s pretty darned expensive. Add potential fines to that waste and your head will spin.
Clogged bin vents and dust collectors can and do increase loading and unloading times; oftenat critical times during the day. Make sure your bags are in tip top shape. With spring approaching and after a winter market with steam possibly affecting the efficiency of those bags, it’s a great time to think about inspecting and or replacing those tired and worn out bags at your concrete plant.
Read on for a bird’s eye view and refresher on the basics of how dust collectors work and how to determine if your dust collector is operating at peak efficiency.
High Capacity Dust Collectors come in two different basic arrangements. There are mixer loading point dust collectors where they just collect dust at the loading point or there are central dust collectors were they collect dust at the mixer loading point and from all silos and bins.
Cleaning of Jet Pulse Dust Cleaners
Contaminated air enters from the bottom of the filter media chamber and flows from the outside toward the inside of the filter media leaving dust particles on the outside of the filter media. Clean air exits through the top.
Cleaning of the filter media is done one row at a time. Pulse jet valves are mounted on a manifold in the dust collector and control air to the blowpipes located above the rows of filter media. Holes in the blowpipes centered over each filter media top opening direct air downward through a venturi into the filter media.
The cleaning operation of the dust collector is controlled by a pulse board that operates the pulse jet valves. The pulse board is energized when plant power (X1) is turned on, so cleaning takes place continually when plant power is turned on. At the end of the production day when the blower for the dust collector is turned off, it’s recommended that the plant power (X1) be allowed to remain on to allow the bags to be cleaned without the blower running. Allowing the bags to be cleaned for ten or fifteen minutes without the blower running affords more efficient cleaning of the bags.
From the factory the pulse boards are set to pulse every 30 seconds (off time) and the duration of each pulse is 125 milliseconds (on time).
Air pressure at the manifold (located inside the bag house) should be maintained at 90 to 100
psi. Less than 90 psi will reduce cleaning efficiency: Greater than 100 psi will cause excessive bag or cartridge wear.
Magnehelic pressure gauges are part of a dependable system to make sure your filtering equipment is working properly, but the gauge readings do not reflect absolute pressures.
CON-E-CO recommends the user of the filtering equipment to monitor the gauges and record readings. Initially, the gauge readings will rise until the bags get a protective coating of material. The readings will then level off at a specific pressure reading. This reading may vary from system to system, depending on the system and the gauge the number is not important. It is to be used as a reference point. After the gauge reading has stabilized, the reading should be recorded and compared with future readings of the equipment.
CON-E-CO recommends that the gauge be read and recorded daily, and if a significantly higher reading is recorded, maintenance personnel should check the bags to see if they are being cleaned properly or if there is an obstruction in an air duct. If a significantly lower reading is recorded, maintenance personnel should check to see if there is a tear in the bags, an air leak in an air duct or if there is an air leak around a door or hatch in the system.
This timely advice and information is provided by the concrete batch plant professionals at CON-E-CO. The information provided is for CON-E-CO equipment. If you have questions about your particular manufacturer’s equipment, please call us at 888-378-6223 for additional information or email us at info@MAconcrete.com .