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Total Cloth area = 144 x total number of bags To the point, what are the possibilities for dry treatment for the so-called moist (sticky) dust, considering dry applications? While they can be fitted with wear protection, this type of blade can still become backed up if the particle load gets to be too heavy. Learn how your comment data is processed. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. The advantages and disadvantages of bag filter dust collector, The bag filter has high dust removal efficiency, can remove fine dust particles, has strong adaptability to the change of treatment gas volume, and can capture a large range of dust particle size, and is most suitable for processing fine particles with recovery value. Areas of concern are the need to maintain a constant down pitch in the ductwork, and greater maintenance costs. These fans will provide an efficient operation, and can be used in Gas streams with light to medium particle concentration. PJ = Pulse Jet. Air Conveyers are used mainly for dry dust applications. This causes the compartment to become pressurized. The large amount of different Wet Scrubbers in use makes it impossible to comment on every single design in this article. Propeller Fans is the most simple fan design. However the advantages of this system are great for their intended applications. Fill large-volume basins from external sources. This ratio is defined as the amount of air or process gas entering the Baghouse divided by the sq. Co-current flow scrubbers The baghouse solution is my preferred solution. This collector has a relatively low efficiency compared to other kinds of Wet Scrubbers. To absorb excess air. A greater efficiency can be obtained by the addition of liquid spray nozzles to further separate the contaminates from the Gas stream. Inspect bags thoroughly. Check fan belts. Large numbers of these Collectors can be installed and used for continuous filtration for a locations dust collection system. Check ductwork for leakage and excessive flexing, Line or replace as necessary. The only way to gain multiple ratings is by varying the speed and the blade setting. With a Reverse Jet or Pulse Jet Baghouse, the same basic design is found as in the other types of Baghouse design, however, with a few very important differences. We usually leave that up to each plant for finding the best methods. Pressurized piping system for wet material (Slurry). ft of cloth in the Baghouse. Liquid is introduced at the top of the collector allowing the dust particles to stick to the wet walls of the collector when they are thrown off by the vortex. Check for unusual occurrences in process. The exact dangers and hazards of the contaminates to be captured, its potential as a public health risk or nuisance, site location, the allowable emission rate by the regulatory body for the given substance, characteristics of the dust, and any recyclable value. Over time a layer of cake dust is built up on the surface of the filter bags. Save my name, email, and website in this browser for the next time I comment. Check gaskets on doors. They benefit from low initial cost, direct return of captured material to the main material flow, and very low space requirements. Check gaskets, valves, and other openings for leakage. it has simple structure and easy operation. Open bleed to pond, thickener, or other drain systems so slurry concentration can build slowly. 5. They usually employ either a Mechanical Shaker, or a Pulse Jet system for cleaning. The Gas stream, as in the Mechanical Shaker design enters into the Baghouse and passes through the filter bags from the bottom leading to the dust collecting again on the interior of the filter bags, thereafter leaving through the outlet port at the top. A bag filter cannot be used when the dust particle concentration exceeds the dust particle explosion limit. In a Reverse Air Baghouse, filter bags are connected to a cell plate on the bottom of the Baghouse and are suspended from an adjustable hanger frame on top. Once all of the preceding material has been examined, the final step in the selection of the proper fan for your system is to consult a Fan Rating Table. Fan dampeners are metal plates that can be adjusted to reduce the energy usage of the fan. Check liquid spray quantity and manifold pressure on mist eliminator automatic washdown. Wet scrubbers have the advantage of low start up costs and low space requirements. For vane-type demisters, spray the center and periphery intermittently to clean components. When the Gas stream enters the collector it is rapidly redirected when it comes in contact with the water surface. My main concerns are the accumulation of wastewater using a wet process. Low Voltage Dual Stage Precipitators contain several grounded plates about one inch from each other with another intermediate plate that also contains a charge. Power supply needs such as voltage, single or three phase AC and frequency Limitations in space This Baghouse has a relatively low Air to Cloth Ratio requiring large amounts of space. Placement in a landfill The air enters into the side of the fan and then turns 90 and is accelerated and thrown out of the fan by means of centrifugal force. A precipitator does not have filter bags, it has large plates that collect dust. Shut down fan, drain the system, and remove temporary strainers. The five principal types of industrial dust collectors that will be discussed in this article are: Cyclone Collectors (Inertial separators) Record the valve positions as a future baseline. When certain types of materials are fluidized into the air they become highly combustible. The stream separates and flows around the droplet. Air Slides are widely used for light dust loads with nonabrasive materials. Clean and dry pneumatic lines associated with monitoring instrumentation. If flow is significantly less than desired, block off rows of cyclone to maintain the necessary flow per cyclone. In these environments, a baghousewill handle and most efficiently filter your dust laden air. A standard 6 bag has a 5-7/8 diameter 2. Clean by high-pressure spraying, if necessary. Check pressure drop across mesh and baffle mist eliminators. The Gas stream enters in one side of the Scrubber and flows horizontally through it passing though the packing media and then exiting out the opposite side Required fields are marked *. Your email address will not be published. This design features a series of blades that extend straight out from the center hub. 2. (Ensure that all compartments of shaker or reverse-air Baghouses are open.). The positively charged plates attract the negatively charged particles causing them to collect on the plates. 4. Pressurized piping systems are needed when transporting the slurry made from using a Wet Scrubber design. The gas temperature during operation needs to be higher than the dew point temperature. The main disadvantages are that they are costly to operate, require a precleaner for any heavy dust loads, cause water pollution that then needs to be addressed, and can erode with high air velocities. Wet Scrubbers are further categorized by pressure drop (in inches water gauge) as follows: Low-energy scrubbers (0.5 to 2.5) Since it is necessary to shut down normal airflow to the Baghouse during the cleaning cycle, this type of Baghouse is normally compartmentalized so as to allow for only a partial shutdown of the system. After being filtered the Gas Stream is then sent through a mist eliminator (demister pads) to remove the excess moisture from the Gas stream. RA = Reverse Air The water hitting the extremely high speed air causes it to instantly atomize. There are a total of 132 bags in the Baghouse Axial-flow fans. Another effective method of dust collection is the use of Wet Scrubbers (Air Washers). The main advantage of this Baghouse is that it does not require a shutdown of any kind to run a cleaning cycle. Wet scrubbers Conduct same shutdown procedures as cyclones. Start recycle pumps with liquid bleed closed. 4. 1. Build up of debris in the inlets, blades, passages as well as obstructions should be checked and remedied ft. Despite this draw back, the simple design remains a noted advantage, leading to this system being widely used in the mineral processing industry. Placed directly in the middle of each set of directly adjacent plates are a series of high voltage (40,000-70,000 volts) DC Discharge Electrodes. While it can be designed to remove a specific size range of particles, it still remains best used as a precleaner to eliminate coarse particles and ease the load on more efficient Dust Collectors further along in the system. Inspect housing for corrosion. I am a process engineer trying to cope with a sticky dust situation (both metaphorically and realistic wise). In this system the contaminated air enters at the bottom of the cylindrically shaped scrubber and rises through a mist of water sprayed from nozzles at the top. While these are an effective filtration system one should note that they tend to be ineffective against fine particles as these tend to be redirected off of the water surface by the high surface tension. The fan blows air over the motor enclosure to provide additional cooling for the motor. When pump cavitation noise is heard, turn off pump and pump gland water. Another important design consideration is whether the Motor is one of these two enclosure designs: Drip Proof and Splash Proof Motor are types of Open Enclosed Motors, which use a kind of electric motor enclosure that has vents to allow airflow but to prevent liquids and solids from entering the motor. However, the fact that it can be fashioned from almost any material and its simple design, which requires little maintenance, leads it to being a wise choice as a precleaner for a more efficient Dust Collector. High Inlet versus Low Inlet Baghouse Design, Constantly cleanedso there isminimaldust build up in the dust collector, Cannot be used when there is humidity of high moisture content present, Cannot handle high temperatures (unless you use special, Units are typically compartmentalized into sections which allows them to be cleaned without shutting off theentire baghouse, Not space efficient (takes up a large area). Induction Motors normally operate on three phase AC current. The patent I am looking at uses two dust collectors. Electrostatic precipitators Check pressure-drop-indicating equipment for plugged lines. This type of fan is commonly used in systems with low resistance levels. Inspect fans for corrosion and material buildup. Baghouse.com is a leading manufacturer of baghouse dust collection systems and equipment with 40+ years of experience serving all industries. He is currently serving as Online Marketing Director & Content Manager at Baghouse.com. General and Dilution ventilation are two common uses for this type of axial fan. Electric Motors are usually grouped as either Induction, or Synchronous designs. Often this process is done while the collector is still operating. A big problem is that positive pressure systems require the dust-laden air to pass through the fan. This step is crucial in order for a proper fan system to be selected. Acceptable levels of noise caused by the fan The two most common types used in Dust Collection Systems are: Squirrel Cage Motors are generally used where a constant speed is desired As with Settling Chambers this type of collector is best used as a precleaner for another more efficient collector further in the collection system. The dust I am dealing with is dry at times and moist at times, depending on the different stage of the process. Check welds. At least once a month, measure airflow by conducting a pitot traverse across inlet to determine quantity and distribution of airflow. Yes, they can operate this way. If material of this kind is present in the system, special equipment such as bin vibrators, rappers, or air jets should be used to ensure that the material that has a bridging tendency does not interfere with normal operation of the hopper. Cleaning is accomplished by vibrating the electrodes either continuously, or at a timed interval, causing the captured dust to fall off into a hopper below. Check hoses and clamps. However these fans are in most applications used only for clean air. For example Gas temperatures above 180 F (82C) will destroy many types of filter media (Filter Bags) used in Fabric Collectors (Baghouses). i m having a final year project bout bagfilters. Fan static pressure There are a vast variety of different designs and applications of this type of filtration system but all of them have three basic operations they perform: Gas-humidification: The gas-humidification process conditions fine particles to increase their size so they can be collected more easily. These collectors are best used when the dust source is isolated, portable or changes position often. While this type of collect can be used in applications where particle sizes are large and only a rough air filtration is desired, the main usage for this type of collector is as a precleaner, to remove larger particles and debris and avoid overloading and damaging more efficient dust collectors. An Electric Motor is what supplies the power necessary to operate the fan (Blower) in the Dust Collection System. Semiannually. His articles have been published not only on Baghouse.com , but also on other industry related blogs and sites. Also the short nature of the cleaning cycle also leads to a reduction in the recirculation and redeposit of dust. Is there a reason why? Check gas saturation, liquid flows, liquid levels, fan pressure drop, duct pressure drops, and scrubber pressure drop. Minimizing secondary dust problems is also a key component in an effective dust disposal system. Straight Radial Blades. Great care must be taken by the operators of this system to ensure that no leakage occurs which would result in an environmental hazard caused by water pollution. What Kind Of Dust Collector Is Right For Me? Removal of collected matter from dry systems can also result in secondary causes of dust pollution and contamination. All Disposal Systems have to accomplish these four objectives without further contaminating the environment, in order to be effective in their role in the Dust Collection System: Collected material from the hopper must be removed 3172 N. Rainbow Blvd. In a Pulse Jet Baghouse, the baghouse filter bags are individually overlaid on a metal cage, which is then attached to a cell plate at the top of the compartment. The sudden larger area for the airstream to pass through causes the air stream to slow down, which in turns causes the larger particles to settle to the bottom of the chamber. Shut down fan and fan spray. Also to be considered is what type of drive system for the fan you plan to use. Use fan current to indicate gas flow. Install temporary strainers in pump suction line and begin liquid recycle. Check that valves are opening and closing properly in bag-cleaning sequence. How to Choose the Correct Baghouse Filter, Have low collection efficiency for respirable particulates, Can be used as precleaners to remove coarser particulates and reduce load on more efficient dust collectors, Suffer decreased efficiency if gas viscosity or gas density increases, Can be designed to remove a specific size range of particles, Have drastically reduced efficiency due to reduction in airflow rate, Are more efficient than single-cyclone separators, Are prone to plugging due to smaller diameter tubes, Have low pressure drop when used as a precleaner, Improper gas distribution may result in dirty gas bypassing several tubes, For a given gas volume, occupy more space than single-cyclone separators, High concentrations of heavy, hard, sharp-edged particles. Collected material may be suitable for backfilling land fills and quarries. Install large-diameter roughing cyclone upstream of high-efficiency, small-diameter cyclone. If combustion process is used, allow hot, dry air to pass through cyclone for a few minutes after process shutdown to avoid condensation. Some examples of instances where this type of collector might be useful are dust-producing operations, such as bins and silos or remote belt-conveyor transfer points. I have being doing research and I havent seen any pulse jet baghouse with the fan upstream of the dust collector. Have collection efficiencies in excess of 99% for all particulates, including sub-micron-sized particles, Do not respond well to process changes such as changes in gas temperature, gas pressure, gas flow rate, gaseous or chemical composition, dust loading, particulate size distribution, or electrical conductivity of the dust, Have lower pressure drop and therefore lower operating costs, Have a risk of explosion when gas stream contains combustibles, Can operate at high temperatures (up to 1200 F) and in colder climates, Can remove acids and tars (sticky dust) as well as corrosive materials, Require large space for high efficiency, and even larger space for dust with low or high resistivity characteristics, Allow increase in collection efficiency by increasing precipitator size, Require special precautions to protect personnel from exposure to high-voltage, Require highly skilled maintenance personnel, Forward curved impeller installed backwards, Change fan rotation by reversing two of the three leads on the motor, Impeller not centered with inlet collar(s), Make impeller and inlet collar(s) concentric, Increase fan speed by installing smaller diameter pulley, Elbows or other obstructions restricting airflow, Install straight length of ductwork, at least 4 to 6 duct diameters long, where possible, Increase fan speed to overcome this pressure loss, Remove obstruction or redesign ductwork near fan outlet, Projections, dampers, or other obstructions near fan outlet, Actual system more restrictive (more resistant to flow) than expected, Decrease systems resistance by redesigning ductwork, Open or adjust all dampers according to the design, Backward inclined impeller installed backwards (high horsepower), Install impeller as recommended by manufacturer, Redesign ductwork or add restrictions to increase resistance, System has less resistance to flow than expected, Reduce fan speed to obtain desired flow rate, Gas Density lower than anticipated (due to high temperature gases or high altitudes), Calculate gas flow rate at desired operating conditions by applying appropriate correction factors for high temperature or altitude conditions, Fan inlet and/or outlet conditions not same as tested, Backward inclined impeller installed backwards, Calculated horsepower requirements based on light gas (e.g., high temperature or high altitude) but actual gas is heavy (eg.,cold startup), Install outlet damper, which will open gradually until fan comes to its operating speed, Fan not operating at efficient point of rating, Motor too small and overload protector has broken circuit. A Direct Drive fan is run directly off of a drive shaft from the motor, this provides for lower space needs, but places the fan at a constant unchangeable speed. Venturi Scrubbers make use of the Venturi effect to accelerate the Gas stream to speeds of 12,000 to 36,000 ft/min. The specifics of the process are irrelevant, since the process does not allow for change in moisture content. However, implementing the baghouse solution might yield extensive operational malfunctions. Air fluidization of the dust is the main operating principle behind this system. The method of contact between the liquid is done in four main ways: Inertial impaction takes place when the Gas stream is forced to flow around the droplets in its path. Notify me of follow-up comments by email. Low- to medium-energy scrubbers (2.5 to 6) Record inlet and saturation temperature of gas stream. Start fan and fan inlet spray. In this system the Gas stream passes through a larger fan that is constantly kept wet with the cleaning liquid. They are highly valuable for use in high temperature Gas streams (boiler exhaust gas on power plants) because of their ability to adjust to the expansion and contraction of metal parts in the system. Inertial separators work by making use of one or more of the following forces centrifugal, gravitational, and inertial in order to separate dust from the airstream. Start liquid flow to all pump glands and fan sprays. These are called positive pressure systems. = (5-7/8 x 3.1416 x 144) 144 x 132 Pleated Dust Collector Filter Conversion: Cost-Benefit Analysis, Industrial Dust Collectors Dust Collection Systems. Great web site. What kind of load is going to be placed on the motor (fan and other drive mechanisms) and power company restrictions on cold starts. There are many reasons why having a proper Dust Collection System installed in your facility is needed, a few important reasons are: To protect employees and society from exposure to pollution, Keep gas stream temperature above dewpoint.