Dust Collector Troubleshooting Guide
Introduction to Dust Collector Troubleshooting
Operating and maintaining an equipment system as complex as an Industrial Dust Collector can be a challenge. Here at Baghouse.com we pride ourselves on being experts in our field, with decades of experience designing, installing, maintaining and servicing every kind of Dust Collect design available. We have prepared this short troubleshooting guide in order to help you solve some of the more commonly encountered issues involving Dust Collectors.
Table of Contents
- Blower (Fan) & Ductwork Issues
- Common Baghouse Issues (All Designs: Shaker, Reverse Air, & Pulse Jet)
- Baghouse Design Specific Problems
- Shaker
- Reverse-Air
- Plenum Pulse-Jet
- Pulse-Jet
Blower (Fan) & Ductwork Issues
Many Baghouse difficulties originate as problems with the main Blower, or Fan and the supply and exhaust Ductwork.
Problem: Insufficient Airflow Rate coming from the Blower, or Ductwork System
- Is your Blower (System Fan) powering on and operating properly?
- Action: Check electrical connections and turn on the Blower.
Addition Questions
- Is the motor pulling the specified proper amount of Amps?
- Action: Check wiring
- Is the fan turning in the right direction?
- Action: Make sure that motor leads are attached to the proper terminals.
- Is there excessive vibration?
- Action: Ensure that there is no excess build up of material on the fan blade, or Blower housing.
Are you getting the proper amount of Air Flow (Cubic Feet per Min) from the Blower?
- Is the Fan Dampener Open?
- Action: Close Dampener.
- Is the air volume at fan rated capacity?
- Action: See Below.
- (If your Blower output is normal) Has the Ductwork System been inspected for obstructions, leaks or design flaws that increase static resistance?
- Action: Redesign Ductwork System to have lower resistance.
Addition Questions
- Are there elbows, or other directional changing Ductwork immediately preceding the Blower Inlet?
- Action: Redesign Ductwork to remove any Elbows, or similar configurations near the Blower.
- Is there an obstruction near the outlet of the Ductwork?
- Action: Removed any obstruction and try again.
Problem: Excessive Airflow Rate
- Is the Blower set to the proper speed?
- Action: Check setting and adjust.
- Is the Ductwork System oversized?
- Action: Evaluate the Ductwork System and consider redesigning if needed.
- Are there any access ports on the Ductwork that are open?
- Action: Close all ports, and ensure they are sealed properly.
Problem: You have High Static Pressure and a low Airflow Rate
- Are there any obstructions in the Ductwork System?
- Action: See above
- Is the Ductwork System to restrictive?
- Action: See above
Common Baghouse (All Designs: Shaker, Reverse Air, & Pulse Jet) Issues
Many of these issues can be resolved with a simple maintenance procedure; others may require a qualified service technician to implement a solution a particular problem.
Problem: There is a higher than anticipated Pressure Drop in the Baghouse
- Have all gauges and pressures sensors been checked for accuracy?
- Action: Clean all pressure taps, check houses for leaks, for proper fluid level in Manometer, and diaphragm in gauge.
- Is the Baghouse the undersized for the application?
- Action: Consider upgrading to a larger unit.
- Is the cleaning mechanism adjusted to the proper settings?
Addition Questions
- Is the cleaning timer working properly?
- Action: Reset the timer. Check wiring, and replace if needed.
- Is the dust not able to be removed from the Filter Bags by the cleaning mechanism?
- Action: Check for condensation on Bags. Dry clean bags, or replace them. Take dust samples and send them to the manufacturer for analysis.
- Is there excessive reentrainment of dust on the Filter Bags?
- Action: Empty Hopper continuously.
Problem: Dirty discharge at stack
- Are the Bags leaking from either the clamps, or are from being too porous?
- Action: Replace Bags, isolate leaking compartment or module. Allow sufficient filter cake to form. Check and tighten clamps. Change to a different Filter Bag; smooth out Bag before clamping.
- Are the seals between the different compartments (Dirty Air, and Clean Air Compartments) of the Baghouse leaking?
- Action: Repair by caulking or welding seams.
Problem: Moisture in the Baghouse
- Is the Baghouse temperature below the dew point?
- Action: Raise gas temperature; insulate unit.
Additional Questions
- Are there any cold spots where pipes or other components connect?
- Action: Eliminate direct metal line through insulation.
- Has the Baghouse been sufficiently preheated (Certain applications only)?
- Action: Run system with hot air only before process gas is introduced.
- Is the system purged properly after each shutdown?
- Action: Run fan for an additional 10 min after processing is shut down.
Problem: Material is bridging in the Hopper, thus preventing proper operating of the Baghouse
- Is there excess moisture in the Baghouse?
- Action: (See previous solutions)
- Does the Hopper retain too much material, or is it cleaned on a regular basis?
- Action: Clean Hopper on a regular schedule.
- Is the Hopper slope sufficient to allow for the collected material to fall?
- Action: Redesign and replace.
- Is the opening for the Screw Conveyor (Or similar device) of adequate size?
- Action: Redesign and replace.
Problem: The Bags fail prematurely, or wear or faster than they should
- Is the Baffle Plate worn out?
- Action: Replace with a new Baffle Plate; Determine whether the Gas stream is striking the Baffle Plate correctly, if it is not, consult with the manufacturer, redesign and replace.
- Is the dust load to high for the particular Baghouse, or Bags?
- Action: Install a Primary Dust Collector (Pre-Filter) to reduce dust loads to the Baghouse.
- Are the Bags being cleaned at the proper intervals?
- Action: Clean less often.
Baghouse Design Specific Problems
The most common variations in Baghouse design regard the cleaning mechanism. The three most common are Shaker, Reverse Air, & Pulse Jet. While the proceeding information applies to all Baghouse designs, the following covers specific design related problems.
Shaker Baghouse Type Specific Issues
Problem: Cleaning Mechanism Does Not Function Properly
- Does Shaking action take place, as it should?
- Action: Check pins, Keys, Bearings, Etc and repair if necessary.
- Is the Shaking action strong enough?
- Action: Increase Shaking rate.
- Have the Filter Bags been checked to have proper tension?
- Action: Tension Bags to proper rate.
- Are any other Baghouse functions affected when Shaking process begins (Fan, or Isolation Dampener, etc)?
- Action: Repair Isolation Damper, or stop Fan.
- Are the different compartmental isolation dampener valves functioning properly?
- Action: Check linkage, Valve Seals, and Air supply of the Pneumatic Operators.
- Is the cleaning cycle set to the proper interval?
- Action: Set to the shortest interval possible between compartments.
- Is the Air to Cloth Ratio at least 3:1?
- Action: Add Bags; Consider installing a larger unit.
Problem: Filter Bags fail prematurely
- Is the shaking mechanism set too high?
- Action: Slow down shaking mechanism.
Reverse Air Baghouse Type Specific Issues
Problem: Cleaning Mechanism Does Not Function Properly
- Are the different compartmental Isolation Dampener valves functioning properly?
- Action: Repair if necessary.
- Do the Bags have the proper amount of tension?
- Action: See above.
- Is the Reverse Air Fan powering up/running properly?
- Action: Run Fan and check differential pressure.
- Does the Reverse Air Fan spin in the correct direction?
- Action: See section: Blower (Fan) & Ductwork Issues
- Is the Air to Cloth Ratio at least 3:1?
- Action: Consider acquiring a larger Baghouse.
Plenum Pulse Jet Baghouse Type Specific Issues
Problem: Cleaning Mechanism Does Not Function Properly
- Is the air pressure at the Pulse Valves within the recommended levels and are all Solenoids and Diaphragms operating properly?
- Action: Check for leaking solenoids and pulse valves; check compressed air source and check differential pressure.
- Are the cleaning pulses at set to the correct duration (0.1 sec)?
- Action: Reset to 0.1 sec.
- Is cleaning interval at the lowest setting the will allow air manifold pressure to rebuild?
- Action: Change setting, and check the differential pressure.
- Do all poppet valves seal properly?
- Action: Adjust and/or repair all valves and check differential pressure.
- Is the Air to Cloth Ratio at least 4:1?
- Action: Switch to pleated media; Consider installing a larger unit.
Pulse Jet Baghouse Type Specific Issues
Problem: Cleaning Mechanism Does Not Function Properly.
- Is the manifold pressure within the manufacturer’s suggested range?
- Action: Check for leaks at the solenoids and pulse valves; Check compressed air source and then check differential pressure.
- Are the cleaning pulses at set to the correct duration (0.1 – .015 sec)?
- Action: Set to 0.1 – 0.15 duration.
- Is cleaning interval at the lowest setting the will allow air manifold pressure to rebuild?
- Action: Change setting and check differential pressure.
- Is the compressed air pressure at the proper level?
- Action: Check for leaks; Increase pressure.
- Is the Air to Cloth Ratio at least 6:1?
- Action: Switch to pleated media; Consider installing a larger unit.
About the Author
| Dominick DalSanto is an Author & Environmental Technologies Expert, specializing in Dust Collection Systems. With nearly a decade of hands-on working experience in the industry, Dominick’s knowledge of the industry goes beyond a mere classroom education. He is currently serving as Online Marketing Director & Content Manager at Baghouse.com. His articles have been published not only on Baghouse.com , but also on other industry related blogs and sites. In his spare time, Dominick writes about travel and life abroad for various travel sites and blogs.
DEARS,
OUR FILTER BAG HOUSE IS NOT SUCING THE AIR WELL.
THERE ARE VUMES & DUST IN THE AREA.
PLEASE SUPPORT ME.
Hi,
Probably following are the reasons
1. Filter bags should be heavily choked,hence ID fan could not suck properly.
2. Fan may be under designed for your requirement.
3. Leakages in the inter connecting ducts, bag filter as well as filter bags
Experiencing high positive pressure at the roller mill house
Hi Chandrakanthan,
High pressure on a baghouse is caused by the filters being dirty. Check the cleaning system and make sure its operating correctly. If the cleaning system is working and you still have high DP then it could be the filters are at the end of their service life and need to be replaced. Less common issues could be the baghouse is undersized for the airflow/dust loading and the cleaning system cannot keep up.
Good Day,
Would you be able to assist.
If we have a calculated air volume of 13,12mcubed/sec – How do we calculate the gross filtration area required.
Fabric Details:
Polyester Needlefelt tubular bags
115 diameter x 3 meter long
Permeability (M cubed/M squared MIN@13mm W.G.) – 6-10.
Many thanks
Mandy
M&B Consulting Services
You need to determine what air to cloth ratio you need for the product. Most are between 3:1 – 6:1. If you want to get specific help you can email us and we will be glad to recommend an air to cloth ratio for your application.
I am looking forward for a bag filter that will be suitable for my system. we have a RVD in which we are using three stage steam jet ejector. before sending our vapors to ejector system we have a bag filter to remove particles of the drying material as the particle size of material is very less. instead of using pulsation we are getting high pressure drop across the bagfilters(50-60 mmHg). Can you suggest me by using your bag filter(PTFE fabric) can this problem be solved.
Do I understand you right, do you not pulse your bags at all? If not, that would be the first step. All baghouse filters need to be cleaned regularly to function properly. Using PTFE membrane bags certainly helps with dust release, but only if they are cleaned using pulse jet, or reverse air.
Very informative blog/site..
I was wondering if there is information available on how to install a differential pressure gauge. I have looked many places and we would like to install it in house since it doesn’t look too complicated. Determining where to drill holes and install the probes seems to be the hardest info to find. Any advice would be appreciated.
I’m having lots of moisture and hot stem coming out of my screws in elevators. When my baghouse cleaning cycle runs to clear it’s self out. I’ve gone up on my baghouse temp 430°F. I’ve also running my cleaning cycles faster. But I’m still getting moisture. What else can I do or any answers …thx
You can try to reduce the moisture content in the process…as its really not good practice to send any moisture into your baghouse if you can avoid it.
Otherwise, you can try making sure that you have everything well above the dew point, from the ductwork, to insulating the baghouse, especially around contact points. You also can look into preheating the system to make sure you have everything above the dew point below introducing the airstream to the unit.
IF you still can’t get rid of the steam, then I would suggest you need to use a fabric/treatment that handles moisture well. Go with hydrophobic coatings, or PTFE.
can used hydrophobic coatings for filters?
i am also facing same issue hot steam is going through the bag filter then always filters getting blocked,,so what is the best solution for this issue ,150c temp under ruining this bags
Hi Sheran,
Any moisture in a baghouse is going to make things difficult. No fabric is going to change that…we can only do things to mitigate the problem.
First, you need to maintain the temp above the dew point as it goes through the baghouse. This also requires following a strict startup/shutdown procedure to make sure you dont have condensation problems at the beginning or end of a shift.
Second, the oleophobic treatment on the bags can help, but only a bit. They do not make the bags waterproof by any means. If you are having any failures in the bags or difficulty cleaning the dust off you might want to consider other fabrics like PTFE membrane or fabrics like polypropylene that have better resistance to high moisture gas streams.
if you are running up to 430 degrees at the inlet of the bag house you wont see any condensation across the bags unless your cake is to heavy and your not getting a good pressure drop. your issue sounds like a lack of draw. Try replacing a number of bags say 10-30 and see if that has any effect. if not then likely you have developed a air leak (ducts have worn out, rotory valve is leaking air (check the paddles for seal – I have solved more problems with my bag houses by servicing the airlock then I care to remember. Try to seal up any equipment serviced by the bag house. close dampers on equipment not effected and open up ones that are. you may also need to adjust your clean air damper to get more cfm’s out of your fan. one other trick that might do it would be to jump up your clean cycle timing to get the bags running less cake.(they should have some as the cake is what does the filtering but it also is what cuts the draw. check and monitor your gauges to see what the pressure is doing. as you stated that after the clean out the problem stops then use that as you ideal pressure and keep the system there. my houses work very good at 1.5 inches of water fair at 2-3 and go to hell over 4.
Good points Dustin! If you cannot reasonably remove the moisture from the process you only choice is to deal with it by maintaining as ideal of conditions as possible in your baghouse.
So as you said, keep the DP as low as possible and keep the cake from forming too much…it gives a place for the moisture to condense and form hard, sticky cake.
Be aware though, that any increase in cleaning frequency will proportionally increase your emissions as well as decrease overall bag life.
What is the desired distance from dust collecting point to bag house? I have several areas in the plants and each area has around 40,000 am3/h of air flow rate to collect dust. How I defined my baghouses, per flow rate? per temperature or with distance? Please advise. Thanks
Helen,
In general, we say that every 1,000 ft of duct will add about 1″ of resistance to your system. Normal systems are designed for 15″ – 25″ of vacuum. Higher vacuum pressures are used, but they are not common. Its best to keep it under 5,000 ft unless absolutely necessary as running such a powerful fan will be expensive and the baghouse will need to be reinforced to handle the extra pressure.
As for defining your systems, it depends on from what perspective. From yours as an operator/manager in the plant, most label them according to what they are collecting, “Clinker cooler baghouse” or “Hammer mill #5 baghouse”, etc. When you are looking at design and maintenance, we talk about them in terms of CFM, number of bags, style of baghouse (pulse-jet, reverse-air) type of bags (aramid bags, top load, bottom load, etc.).
Dear Sir We have a high D.P pressure even at low loads any ideals?
How old are your bags? Once your bags are old and blinded they will get plugged up very quickly no matter how light the load since they can no longer be cleaned effectively.
Otherwise, I would recommend looking at the type of dust you are collecting and make sure you have the correct kind of filter/treatment selected for that dust. Try switching to PTFE membrane coating.
You might also need to adjust your cleaning settings. In a pulse jet you might have weak or uneven pressure. Your pulse valves could be old and leaking when they fire. The blow pipes could be misaligned, insufficient airflow in the header, wrong settings on the timer board, etc.
Dominick
We have a Hocker Polytechnik baghouse in our single stream recycling facility. It’s purpose is to collect plastic bags thru an air lock and deposit them into a bin. There are 5 ports along the production line that air is drawn. The past few weeks the system has been loosing suction at all locations the farthest point even more so. We have cleaned the filter bags, all 288 of them. Upon restart after the cleaning the system appeared to be operation properly, but within a few minutes we noticed the amps dropping from 100 to 65. Not sure where to turn next .If you have any insight it would be very appreciated.
Thank you
Andy Tomasello
Plant Manager
City Carting & Recycling
Andy,
Thanks for sending us the question! Sorry for the late reply, as I have been away for the last 2 weeks.
It seems like you might have some kind of electrical problem with your fan, as lose of power is usually independent of the filter system. Also, its very likely that although you “cleaned” the bags, they plugged back up very quickly. Cleaning of filter bags not not best practice as they are not designed to be cleaned, washed, or anything like that except online by the air pulses. Many times, users do more damage to their bags by attempting to “clean” them than they do just leaving them alone. The only real solution for blinded bags is to replace them. If they are blinding fairly quickly after you change them it may be that other conditions are not optimal and you need to improve system efficiency (many factors impact efficiency).
Has the situation improved since you posted your comment?
Hi,
We have a dust collector for our kettles (gypsum),during operation we observe that when dust filter is operating we still have positive pressure on the inspection hatch point on top of kettle.
If our dust collector is working proper, what I feel that we should have only negative pressure.
Could you please advise something.
Thanks,
Thanks for your comment. I am a little confused about whether you are referring to the baghouse or the kettle itself.
IF BAGHOUSE
Are you getting a reading of positive pressure on your magnehelic gauge or is the air rushing out when you open the hatch? I don’t see how you would have positive pressure on the clean side, regardless of whether the filters are dirty or not. The system fan is pulling air out of the baghouse at the outlet so it should be negative or worst case close to neutral if the bags are 100% blocked (which is not realistically possible).
Sounds like your airlines are swapped on the magnehelic gauge. Otherwise, your fan could be spinning backwards as those are the only explanations for why you would have positive pressure in the baghouse on the clean side.
IF KETTLE
You must have excess air coming into the kettle beyond that supplied by the dust collection system. Likely the air is bottlenecking in the baghouse because the filters are clogged and restricting the airflow. Even if the filters are not blinded, the baghouse could be inadequately sized to allow the needed airflow through the system, thus building up pressure on the kettle.
We are trying to run Fuel Pellets instead of coal in a Stoker Boiler and the filters are blinding over and creating problems in the bag house. Any ideas on what could be causing this.
Mark,
Thanks for submitting the question. It could be a number of different things. Each baghouse is designed to run for a particular application, changing anything can upset the original balance…certainly switching to another kind of fuel requires some modifications to the dust collection system.
It could be that the pellets are throwing an increased/decreased dust load on the filters and your cleaning settings are no longer optimal for that mix. It could also be that the fuel pellets have a different chemical makeup that are somehow affecting the filters (e.g. more acidic gases, higher alkali content, etc.).
Can you provide us with a better description of your process and the baghouse specs? (Namely, the type of unit, filter style, number of filters, fabric/treatment used, air to cloth ratio, total CFM, etc.)
The Lines feeding our bag house are having excessive product build up. The product is settling on the lines. You can stir the product up and what is stirred up will be taken into the system, but some settles back down on the pipes. Can you provide me some help in this scenario?
Brandon,
Thanks for contacting us. It sounds like you are differing from product drop out in the ductlines. This indicates your airspeed in your ductwork is below the minimum conveying velocity for the product. Most fall within 3,500 to 4,500 ft/sec. If it drops below that you will have the product falling out and building up in your baghouse.
Ill follow up by email with you to see if we can get some more information and help you.
Hi
We have a problem with our dynaclone (Baghouse) Coal dust is escaping from the inspection doors. we recently changed our filter bags but after 3 weeks the problem re-occured. Could it be that the exhaust fan is not exhausting enough air from the baghouse?
Aubrey,
It sounds like you have dirty air escaping from the view ports on your unit, is that correct? IF that is so, the first thing you need to do is replace the gaskets around the ports. If that does not fix the issue, it could be that the filters are overloaded and blinded. If that happens the pressure on the dirty side of the baghouse might rise higher than normal and you would get some leaks around the hatches.
More likely than not, the problem is the gaskets (which need to be replaced regularly).
If you would like, we can get you pricing on some replacement gasket if you send us a picture with some basic dimensions and a request for how many feet you want.
we have a cyclone dust collector on a joy drill rig. the blower fan is working but the pulse jets stopped working and no longer purges air. any ideas?
Scott,
Sounds like you have two systems mixed up. Cyclones do not have pulse jets, baghouses have pulse jets. If you mean that your baghouse pulse jets have stopped working, that could be caused by a number of issues. Check the solenoids and the controller connections to make sure everything is good. Solenoids do go bad overtime so you might have to replace them.
Also, it could be the air header, pulse valve connections are bad. The valves won’t fire if there is no air in the air header tank. So check to make sure its being filled properly.
Sir,
Our coal dust plant we using off line pulse jet type bagfilter,
But after tripping ID fan huge dust fall down from bags.and accumulated in bagchambers.
Why it’s happened???
Pressure 4bar
Off line isolationa valve also OK..
Let me know if I understand you correctly…When you pulse the bags offline they drop huge amounts of dust into the baghouse hopper and this then clogs up the discharge? What exactly do you mean when you say “tripping ID fan”? If you are using a fan that blows back into the unit this is actually a reverse air dust collector. Pulse jets are designed to work online, there is not really any reason you should only trigger them when the unit is offline.
IF you have a problem of too much dust coming off the bags when you clean and it overwhelms the discharge, then you should try cleaning the bags more frequently, possibly while they are online (if you do actually have a pulse jet). IF you have a reverse air baghouse then you need to clean the bags more frequently to prevent such a massive amount of dust from building up between cleaning cycles.
I think nithi means the induced draft fan. When that trips the suction is gone and a lot of dust drops. It sounds like normal cleaning, online or off, isn’t knocking off enough dust.?
In either case, when the suction turns off you should have dust falling into the bags in a pulse jet or in a reverse air. The dust should be falling off into the hopper. If too much dust falls off at once (especially with certain sticky dusts that accumulate easily) the dust can bridge across the hopper discharge and the resulting blockage will pile up high into the collector. In time it can even reach the bottom of the filter bags.
Dear,
Our filter house bag is not blasting; it is always piling up dust. we had to clear out the dust manually all the time. Kindly help please
Can you tell me a little more about the system? What kind of baghouse is it? Maybe send some photos as well. Once we know more we can help you with the problem.
Hello,
We’ve got some baghouse troubles and I’m looking for some ideas. Here is some background; We incinerate sludge from a wastewater treatment plant. Each of our 3 incinerators has a baghouse consisting of 3 modules running in parallel. 272 bags per module with an average flue gas flow of 17,000cfm. The middle module / hopper on train 3 repeatedly plugs up right after clearing. This has been a problem for years. It is disastrous as the inlet duct becomes smaller, velocity increases and the bottoms of the bags get sand / ash blasted through. What could cause this? From reading your blog it looks like I should be looking at leakage causing moisture and bridging.? The ash removal system seems to be in working order. The transporter gets hot so I know it is getting some ash. Thank you
Scott,
Thanks for sharing!
Is the inlet duct becoming smaller because the duct diameter is reduced going into the unit or are you saying the product slowly builds up in the duct, blocking it off and making the air pass through a smaller area (and thus increasing in speed) ?
If its the first situation (duct is reduced to a smaller size going into the unit) then its a design flaw. If the air is coming it so fast that its tearing up the bags then it probably is a result of poor design from the system OEM or modifications have been made to the system by non-baghouse engineer or to the operation (all three are very common in the field).
If the duct is being closed off by build up of dust you have a different issue. If its settling in the bottom of the duct and building up you could have an issue with product dropout from a air speed within the duct (dropping below the minimum conveying velocity).
A possible solution to the bags being abraded is to switch to pleated elements. Since they are shorter the air has more time to slow down and allow for the heavier particles to drop out before reaching the filters. This is only possible if the temperature and chemical conditions allow for use of pleated elements.
No matter what the cause is there is certainly a better way to operate. You do not need to battle with abraded bags for the long term.
If you would like to discuss this more in depth you can email me directly at info@baghouse.com, or give us a call tomorrow at (702) 848-3990. Perhaps we can work it out by phone or we can discuss having us conduct a site visit to find a solution to your problem.
Thanks for the reply Dominick.
To clarify; The hopper is filling up to, and higher than the inlet duct. The product is not dropping out. When ash is filling the hopper to this level the velocity is increasing, trajectory changing, and hitting the bottom of the bags causing holes. This is not a problem with clear hoppers. What could be causing this to happen repeatedly in this module? What are some methods or tips & tricks for unplugging this hopper while online?
Years ago we did try some short pleated (shop vac style) filters. They didn’t seem to work well as plugging was a big problem. A combination of 12′ and 16′ bags seems to work pretty well. Sorry about not emailing direct. I wanted to continue sharing in case others are having the same problem.
Scott,
Ok I have a better picture now of whats happening. The dust is not emptying from the hopper faster enough during peak loads. This is causing the issues with the increase airspeed, etc.
Here’s a few things to try:
– Check the airlock and make sure its operating correctly. If there is another wrong with it you may want to look into getting a better airlock with a faster discharge rate.
– It could be the airlock is fine, but the material is bridging over the discharge. This tends to happen with sticky dusts or dusts that can easily form clumps, or if there is a high moisture level. Many times you can install vibrators on the hopper walls to help with this problem.
– If its a moisture problem you can look at ways to lower the moisture content before it enters the baghouse or keep the temperature high enough above the dew point so its not an issue.
The pleated filters may have been the wrong variant for the application. If the pleat depth is too short or the pleat count too high the same bridge effect can happen between the pleats on the filters. It could also be that the air to cloth ratio was not done properly or that too many filter elements went into the unit and you have high can velocity and interstitial velocity, which can prevent the files from being cleaned properly. You may also have benefited from PTFE membrane to help with dust release, or the pulse jet settings could have been wrong. If done correctly pleated filters often work wonders in ash applications like this. I would suggest you look into them again.
Mixing bag lengths is not always the best option as it itself messes with the aerodynamics within the unit and causes disruptions within the airflow. IT could be contributing to the problem as well.
Fantastic website! We have a jet pulse baghouse with 323 12ft PTFE bags and system rated at 30″. When we started operations we were within the 4″DP and static pressures for dirty and clean sides have generally been -23 & -27 at the start. We had a faux pas in hopper clearing frequency briefly and I had to change a row of bags that had their bottoms abraded. After replacing bags and vacuuming the clean side, the DP is still achievable but static pressures of -15 & -19. Is this positive movement attributed to the bags becoming more seasoned or should I be slightly worried about reading accuracy. Since starting in September, I have not cleaned the short steel sensing lines.
Jason,
Thanks for your comment here. You are still maintaining the 4″ DP, but your vacuum has gone down, correct? If correct, the lower pressures indicate that your fan is not pulling as hard since the clean side vacuum is much lower. 19” vs. 27” initially. You should check your fan output. This is not due to “seasoning” of the filters as the vacuum after the filters has been reduced. The fan should still pull the same Static Pressure [clean side/high number] unless you turned it down somehow. You must continually clean the static lines to avoid false readings. You can read our articles about DP troubleshooting here:Baghouse Differential Pressure – How to Troubleshoot False Readings
If you are still having problems you can consider having us come out to inspect your system. We offer our audit services at very reasonable rates and even offer rebates that can potentially make our audits free. See here for more information or give us a call or email.
Thanks Dominic, would look into that asap
Comment
We are a dry corn mill. After temper process we degerm the corn then dry it down for customer specs. Our cr288 filterhouse for our fluid bed dryer which dries the degermed corn (indirect heat)has started to condensate and plug apu lines and cause downtime problems daily.
We haven’t added or took away from this setup in 3 years. Although filterhouse is insulated along with trunk lines,from discharge conveyor and airlock on it is not. Dust collection is transferred back thru mill via closed loop system with degermed corn to dryer then picks up this filterhouse. Product has historically always been damp but this is dripping wet water/flour/dust sludge that cakes lines solid ino some sweeps. HELP
We haven’t added or took away from this setup in 3 years. With all the problems listed something has definitely changed. It may be the corn that they are starting with, the insullation on the equipment sand conveyors or something in the building/weatherproofing, etc. Re-check entire system for changes.
BH has started to condensate and plug apu lines – problems daily. #1 – What are APU lines? #2 – Condensation comes from temperature differences in the system. Insulation helps this problem however it sounds like something else has changed. Any changes to the equipment, conveyors, transfer points?
Filterhouse is insulated along with trunk lines – from discharge conveyor and airlock on it is not. If the product comes out of the Baghouse hopper at a temp higher than the dew point temp then condensation will occur. Have they raised/lowered the temp of the product for any reason? Insulation and occasionally heated hoppers/conveyors are used to solve the problem.
Dust collection is transferred back thru mill via closed loop system with degermed corn to dryer then picks up this filterhouse. Sounds like you are feeding the wet corn product right back into the system along with the moisture. Is the dryer removing the same amount of moisture as before the problems started?
Product has historically always been damp but this is dripping wet water/flour/dust sludge that cakes lines solid into some sweeps. Sweeps referring to ductwork? If ductwork then the product being transferred is too wet at too low of a temperature to start with. Below dew point will cause condensation.
Additional Questions:
Where is this plant located?
Has the local weather been unusually rainy/snowy or above/below average recently?
Has the raw materials supplier changed anything?
Any problems with the dryer itself?
Hi
Our bag filter house is not discharging dust continuously. Dust get surge out once in a day. DP get raised from 70 to 100 before surge out and reduced to 70 after surge out. Since the dust is added to our process. It gets affected drastically. Plz help.
Premkumar,
Is that 70-100 inches of water? I think you need to take those measurements again…
If you are having discharge problems it could indicate a leak around the airlock, high dust loading (too high for the size baghouse indicating high air to cloth ratio, can/interstitial velocity, etc.) You should also try having a rotary airlock to make sure the dust is emptying at all times and does not have a chance to buildup.
Hi,
Can I install the temperature gauge at Dust collector pipeline? If yes,is it on inlet or outlet? Kindly help me to solve this doubt..
Thanks..
You can measure it both before and after if you want…but usually its best to know the temp before it enters the unit so you can use that information to guide fabric choice among other operating variables.
Hi I worked at a battery company our lead oxide mill gets blocked up and we often run it in manual to run the build up out through a star valve. The oxide builds up over the middle screw which then trips the bad house.we have tried a vibrator on the out side of the bag house and a bigger star valve non which as worked. When it blocks up it is mostly at back fills on the entry of the oxide in the bag house any ideas will be welcomed thanks Michael
Michael,
It sounds like you need a faster discharge, we supply fast dumping rotary valves that might help. You also need to make sure that you always have the value running and that you NEVER allow dust to build up inside the hopper. If it simply overwhelms the discharge when it hits a peak load then you might need to look at installing a pneumatic conveying system of some kind instead of just dumping into a dumpster or drum. If that doesnt work then you can consider using some kind of pre filter such as a cyclone or knock out box to remove the majority of the particles before it enters the baghouse. The also has the effect of improving efficiency and service life on the filters in the baghouse since they then only handle the fines as opposed to all the coarse particles and the fines.
My dust collector not working. Flue gas goes directly to the chimney and taking ash content which came out from the top. I install obstacle in the path of flue gas but still problem exist. Tell me what can do so that ash content come out through dust collector.
Rishu,
It sounds like you have the gas bypassing the unit. you should check that any diverters, dampers, etc. are in the correct setting. IF the dust is passing THROUGH the filters then you likely have massive leaks or you have too small of a baghouse to handle the amount of gas you are trying to pass through it
Hi
We have a cyclone system for paper dust removal.
Our 12 bags will fill up with dust but not the 55 gal
can.
In the past, the can would fill first.
Can you help?
Hi Dallas,
Sounds like an issue with the discharge. Do you have an automatic dumping valve at the bottom of the cyclone (double dump valve or rotary air lock)? If so, you need to check the settings and see if its running properly.
We have no automatic valve at all. Open from the top to bottom of the cyclone into the 55 gal drum.
Great info here.
Good day. Found dust on stack on our cement bag house.(pulse jet bag house)
Done inspection on filter bags, found 2 bags full of dust inside.
Done changing 2 new bags. However, I unable to find any hole or torn at those 2 old bags. Wondering where and how the dust flows through those 2 bags?
Please advice.
KK,
Im glad you like our site! We work very hard to have valuable information here on the site for your benefit.
REgarding your filled bags it could be the holes are too small to notice or it could be a leak in the seam or near the tubesheet thats causing the dust to collect inside. At very high airflows (when you exceed the recommended airflow for the baghouse) you can actually begin to see dust pulled through the fabric due to the high velocity alone. Check the bags next time with leak detection powder and black light (leak testing) and then verify if the airflow is within proper parameters.
l work in a tobacco company,in charge of Dustroom’ the problem l have now that, the production section does not have enough suction for production, how can solve the problem
Normally, increasing airflow to a collector is not really possible without expanding it or installing a new unit. Sometimes you can switch to pleated filters and increase the airflow. Send us the operating specs and specs on the unit in question and we can review it to see if we can expand capacity with the pleated filters alone. Use the contact form to send the data.
Hi,
I work at an asphalt plant. We have installed a new baghouse. We are having trouble getting the baghouse inlet and outlet temperatures up high enough. Would like to see outlet at 212degrees, but it is only about 140 degrees. Aggregate temps are good. With low temps on baghouse we are not getting the moisture out. Please help with any suggestions thanks,
Jeff
Jeff,
It could be a lot of different things. Are you bleeding air in anywhere along the way thats causing it to drop? Also, how sure are you of your temp readings on the kiln?
It might require insulated ductwork or unit heaters to keep the unit above the dew point or a combination of things.
Give us a call and we can walk you through a few things.
We plan on placing a Humidity/ temperature/ dew point transmitter – EE 310 ( has 2 x 4-20 Outputs and 2 Alarm outputs))
http://www.ecefast.com.au/humidity-temperature-dew-point-transmitter-ee29-31
, in our Dust Collector used for venting a Grinding Mill to allow us to maximize the wet material inputs. I would think that it should be placed in the coldest possible area (outlet of the Dust Collector) , we already have a separate inlet temp probe. Your thoughts?
Hi Brian,
I would suggest you monitor things at the inlet of the baghouse…once its going out its not of much use to know the conditions unless you are comparing it to the inlet conditions (maybe correlating how much moisture/temp loss you have through the baghouse).
How do you monitor emissions levels? Have you looked into triboelectric emissions monitors?
Hello,
I work in a cement plant where a baghouse is used at the exit of a cement mill. It was discovered that after the bags were changed and the mill started up, that blaine on the cement started to drop after 4 hours of operation. Air flow checks revealed the air flow was dropping of. When the mill was stopped and bags allowed to pulse and clean itself and mill was restarted, same trend occurred, blaine started to drop after 4 hours of operation. I contacted the guys who installed the filter bags and I was told no pre-coating was used. Can this be my problem?
Hi Shastri,
IT could very well be the problem. When things stop working, its important to determine when it started malfunctioning and then see if anything has changed with the process or with the dust collection system. If the bags were damaged by not precoating them, then you will need to get a new set of filters. Alternatively, you could try installingPTFE membrane filters, which do not require precoating.
Hi,
In our phosphate mine,there is spillage case in the discharge line of dust collector,Spills occur although all rock phosphate spill on the conveyor, spills to outside occur because this phosphate particles are very fine particles and can be suspended in the air.
There is a double flap discharge type to discharge the dust in to the conveyor. This dust being collected is dumped on to the conveyor at high velocity (By Gravity) resulting in spills across the conveyor.
I have recommended to provide a vacuum line on the top of dust discharge line and to be connect with same dust collector to reduce the spillage of these fine particles.
Note:conveyors are covered.
So I need your opinion and what do you think in this case??
Thanks a lot
if you are going to enclosure the conveyors then you need to provide sufficient dust collection suction to ventilate the entire run. IF you do not provide enough suction then the dust will buildup inside and cause lots of problems. Some dust collectors are made specifically for being installed on the conveyor lines and then dump directly back onto the conveyor when the filters are cleaned. That might be your best solution. Otherwise you need to run ducting to the lines and then have it go to a large central collector.
Having trouble getting the belt pully and bearings off the fan shaft any tips?
Im not too sure whats causing the problem. With regards to fan specific problems its best to check with the fan OEM for their assistance.
I work at a grain elevator and we have a serious issue. It has to do with our scale floor the lower garner is being pressurized and completely wiping out 5th and 6th floor. We have a quite large dust system sucking off the scale and 3 of our legs. This issue did not happen until 15 years ago from what I have heard but it had gotten so bad. I’m going to replace the airlock, the bags have been done but something I have noticed it gets bad on humid days. What do you think I will do my best to relay information.
Hi Travis,
Thanks for writing in with your problem.
It sounds like you are having problems with the collection system not being able to keep up with the dust generated. I need more information to determine exactly whats happening but it could be the high humidity gets sucked into the baghouse and its causing condensation thats caking up the dust into a thick, wet layer on the bags that the cleaning system then has a hard time removing.
Thanks for your reply! I did mean to say check the airlock but anyways. That’s what we are thinking for some reason that dust system cant handle the amount of dust. I will reply back once I have more detailed information
This may take sometime. But is there a way to support this dust system without replacing?
Side note. Loading oats seems to be a factor.
The dedusting system I work in handles the dust of raw material (iron ore and coal). The fabric filter length is 1.7 metres with 3-5bar of pressure(pulse jet) used to clean the bag..if we increase the bag length to 3meters.. Would the pulse jet air used to clean the bag will be same or need to be increased? If increased, how much??
If you go to longer pleated filters you need to recalculate the air pressure, but also the blow pipe size, height, hole size, etc. Many things go into it when you switch the filters to a different style.
When we power off our Dust collector system after few minutes there is a fines coming out from the machine dust capture points.We face this problem only in summer session
DP 85 mmWG
Flow 15000 cfm
Purging Air pressure 6 bar
Duct Network is cleaned
Hi
I work in a sand mineral separation plant and recently we are facing an issue with our jet pulse baghouse:
– the dust are captured on the bags but when the jet pulse happen, the bag cleanning doesn’t happen
– the cleaning happens only when we stop the extracting fan or close 100% the damper valve and pulse on manual mode
We have checked the pulse jet air jet pressure and it is on spec
The unit was functionning for 10 years without change but it is a recent issue
Thanks for the help.
Hi Mana,
This sounds like a textbook case of the baghouse having a high interstitial/can velocity. Was the airflow to the unit increased recently? IS there now more dust being sent to the baghouse? IF so, its likely overloading the system and overpowering the cleaning system so that it can only function when the system fan is turned off.
Otherwise, it might the cleaning system has low air pressure, the valves are in bad condition or the cleaning controller is not functioning properly.
Thanks for your reply.
Could you explain more the high interstitial/can velocity phenomena?
No change was recorded on the airflow.
We have noticed that the issue started after that we have changed the top section of the baghouse plenum (due to corrosion issue).
No change on the cleaning air parameters (pressure is OK) and all valves, air dryer, solenoid valves, are well functionning
Hello!
First I would like to say thank you for your postings. I have found them all very helpful. I appreciate the work you are doing and helping all these people out.
I am having a slight problem with one of my pulse jet type baghouses. We take trend data on our baghouses for troubleshooting and it appears that one of my baghouses differential pressure is fluctuating by a whole inch of d/p when it’s not in use. When in use, the rise in differential pressure is fine and the pulse down occurs when required as expected, and it falls to the expected d/p. I do not see any fluctuations when it’s in use. When the baghouse is not in use though, the d/p rises and lowers by a full inch every minute or so, maybe even more often. I do not see it continuously pulsing down when I inspect the baghouse, and the instrumentation and pulse board are all working fine according to my troubleshooting.
I would greatly appreciate any help you could offer me.
Hi Brandon,
My first guess would be that somehow the baghouse continues to have some kind of airflow through it when its off. Maybe its connected to another system via ducting that continues to generate draft even when the unit is off? Or maybe its part of a multiple compartment baghouse and the isolation dampers between the modules are not sealing correctly.
We have bag house at cement plant RM area ,main bag house after we replaced all Fiberglass bags still dust emissions
Hi Mustafa
If you replaced the bags and its still leaking you need to do a dye leak test to see where the leaks are coming through. It could be the tubesheet is leaking and needs repair. Also the filters could be installed incorrectly. This is especially common on larger baghouses or when inexperienced laborers do the changeout as they could easily install a few bags incorrectly if they are not being supervised properly. You could also have extra fine dust and if you use normal medias without precoating you can see dust bleed through even on new bags. You may need to sufficiently precoat the bags or switch to a media with ePTFE membrane or a similar high efficiency media.
Hi, we are having a bag filter dust collector system in Ash handling plant of coal fired thermal power station. We have 8 bag filter system but in a particular system facing problem of High DP from last 6 months. We changed all the bags 2 times but no effect on DP was seen after that also. In remaining 7 and in this particular bag filter system,everything is same e.g. Purging sequence,purging air pressure,bag size etc.
As soon as its DP comes in increasing trend,vacuum pump amps comes in down trend. Can you help in this…??
Hi,
If the DP is still high even with new filters its possible the baghouse is undersized. You could have too high of an air to cloth ratio and the system simply cannot keep the DP lower via the cleaning system. What is the air to cloth ratio?
Hi
Air to cloth ratio is – 1:1.
Air load is 3000 m3/hr with 65 MT of Ash.
Fabric material is – PAN. 3R5.
Purging air pressure 6.5 bar and purging timing is 7:2 seconds Off:On respectivly.
Actually we are having total 8 same type of bag house system but facing this problem in particular 1 syatem so undersize is not an issue i think.
It could be an issue with the pulse valves. Are the diaphragms in good condition? Does the air header have water/dirt in it?
Also please confirm the ON time you have for the pulses. Do I read correct you have the ON time set to 7.2 seconds? As in the pulse valve opens for 7.2 seconds each time?
ON time for the pulse valves should be something like .08 – .12 seconds. More or less than this and you will have a severely weakened pulse.
This is a rotary step baghouse not a pulse jet.
By rotary step, do you mean a rotating arm low/medium pressure reverse air baghouse? Rotary step is not a standard term so I’m not sure what you are referring to.
After every 25-30 minutes bag filter DP reaches at its peak point, then operator opens the vacuum breaker to kill the system vacuum. As soon as he opens open the vacuum breaker, the DP becomes zero and then starts increasing as soon as the deashing starts.
This phenomenon repeats.
What could be causing my drum to steam and at my discharge chute? I have a rotary step bag house i have check all roto steps for proper working condition. I have also check my slam dampner, and exhaust fan blades there all straight up and down. I have a Very able speed exhaust fan. No matter if its 50% up or 100% doesn’t seam to slow or help with steaming. I have sucked all bag out and cleaned them. I have also check duck work for build up none was found clean and dirty side. I have recently switched from methane to natural gas. Tunning guy should be here in two weeks to check tunning of the burner. I have check rotation on blower motor and also to make sure the dampner is working there and blades are not sticking / stopping air flow. I have changed all combustion flights as well. I’m clueless and never seen nor heard of a plant doing this. I was steadly able to run 350 to 380 tph all summer no problem now hardly able to run 225 to 250 tph . Any help would be much appreciated. Thanks in advance.
Hi Chris,
Thanks for contacting us. It sounds like you are getting leaking through your baghouse on a rotary dryer. Is that correct? There are many things it could be. Its difficult to tell from the short description but one thing that caught my attention is you said you “cleaned the bags”. Dust collector filters are not designed to be cleaned, as in washed with water or detergent. Even taking them out and blowing them down with compressed air will not do the trick. In fact, any of those methods will usually cause further damage to the filters as they are not designed to withstand that treatment. IT may be that your filters are blinded and leaking. By taking them out and attempting to “clean” them you may have damaged them further causing more leakage.
Have you done a dye leak test on the unit?
If you want feel free to email us directly here and we can talk you through the issues in depth.
Thanks for mentioning that hoppers can retain too much material and prevent proper operation if they aren’t cleaned regularly. According to my knowledge, you can use a flow-aid device in some situations to resolve issues with material clogging. Your article explained common hopper issues in a clear way, so I appreciate you discussing this info.
Our ballmill DBC Filter bags regularly getting jammed with the duration of 30minutes. Air pulsing working with 6bar pressure. Our filters length was 2mtr. Can you give any solution for this.
I am facing a problem in my bag house. There is a heap getting formed in the middle of bottom hopper and it is getting hold up over the screw. The heap is so high and screw is not able to drag it towards the discharge rotary valve. What can be the cause and what to do.
Hi Yashpal,
Thanks for submitting your question.
Removing dust from the hopper quickly is essential for proper operation of your system. Storing dust in the hopper can lead to filter failure, plugging and other process problems.
If you have bridging over the hopper discharge you may need to look at the discharge device. In some units you have a trough hopper with a screw or drag conveyor that moves material to the middle or the end to discharge through an airlock. (I believe thats what you have here based on your comment.) In that case, you might need to increase the speed of the screw/airlock to empty the dust faster, before it has a change to build up and bridge over. You may also need to look at things like hopper vibrators to break up the dust.
If the dust is exceptionally difficult to remove you may need to look at redesigning the unit/hopper to have a larger opening or to remove the trough hopper style for a pyramid hopper with a very large discharge.
Can you tell me more about the kind of dust you have and how long this problem has been going on for?
Dear sir,
Thanks for your reply. You are getting the point.
I have started my plant after 4 months shut down. Bags are newly replaced with ptfe membranes type. Dust is of calcium hypochlorite. This is issue I am facing since I have started my plant. It looks like powder is not getting distributed over the entire screw.
Dear sir,
Thanks for your reply. You are getting the point.
I have started my plant after 4 months shut down. Bags are newly replaced with ptfe membranes type. Dust is of calcium hypochlorite. This is issue I am facing since I have started my plant. It looks like powder is not getting distributed over the entire screw.
Great presentation! I appreciate your willingness to share the action for each question. Thank you for sharing!
Please Sir,
This are the following problem I’m having with Air jet filter
(1) the filter is generating hot air
(2) the Air cycle is not working perfectly
(3) the filter instead of sucking dust but is blowing out dust
Please I need some help
I need to communicate about cement technology specially bag filter pistons and problems and its solution