Showing posts with label hopper heating. Show all posts
Showing posts with label hopper heating. Show all posts

Prevent Bulk Material Flash Freezing in Hoppers and Chutes

FRP heating panel
Heaters in stalled on a chute.
A phenomena know as “flash freezing” occurs when aggregate material with trace amounts of absorbed water comes into contact with very cold metal surfaces, resulting in the aggregate instantaneously freezing.  The frozen material then instantly bonds to steel chutes or hoppers (which are at sub-freezing temperatures) causing an immediate, and possibly catastrophic, block in the hopper or chute.

Once this occurs, the cure is often a jack-hammer or other type of brute force method to clear the obstruction It's common for any coal mine, quarry, cement manufacturer, mining facility, or power plant to have a sledge or jack hammer on call for just this purpose. A far better approach is to prevent  sand, cement, ores, and mined products from freezing in the first place. 

The best solution are electric FRP heating panels. FRP heating panels are waterproof, dust tight, and vibration resistant electric heater panels that mount to the exterior walls of the hoppers and chutes. 
Specially designed for use in high shock and high vibration applications, their robust construction and corrosion resistance provides long life. 

FRP heating panel
Multiple heaters on a round hopper.
Because these atmospheres are normally dusty, and occasionally ignitable,  FRP panels are available with FM approval for use in hazardous areas. Furthermore, because hoppers, ducts, and chutes come in a never-ending variety of sizes and shapes, FPR panels are easily customized to conform in shapes and size to virtually application. 

If you work in a plant or facility where bulk material absorbs ambient moisture, and the possibility of freezing exists, you should learn more about FRP heating panels and their benefits they provide in reducing downtime, and more efficient operations. 

Don't Let Frozen Aggregate Clog Your Process Equipment

FRP hopper heaters
FRP hopper heaters
FRP chute heater
FRP chute heater
Processing lines in coal mines, quarries, cement plants, mining facilities, and power plants have a special problem in very cold weather. The coal, sand, cement, ores, or other mined products they handle can freeze and cause equipment outages. The combination of trace moisture mixed with aggregate material, plus freezing temperatures, combine for major problems with conveyors, hoppers and chutes. When the aggregate hits the cold steel surface, it instantly freezes (flash freezing). The bond between the frozen aggregate and the steel wall is virtually unbreakable, and can cause long down-times with the equipment. Maintenance people have their own, time-tested curative solutions - torches and hammers - but installing preventative measures is clearly preferable.

FRP trough heater
FRP trough heater
The FRP heating panel, a waterproof, dust tight, and vibration resistant heater is an excellent preventative solution. FRP heaters are designed to be used in the high vibration, corrosive and dirty areas where they are installed. Available with FM approval for use in hazardous areas, they provide an easily customized panel that conforms to the shape and size needed to fit any chute or hopper. Additionally, they are lightweight, can be applied to flat or curved surfaces, and are very easy to install and maintain.

FRP trough heater
FRP trough heater
For more information on chute, conveyor, hopper or pipe heating, contact the experts at Hotfoil-EHS by visiting www.hotfoilehs.com or calling 609-588-0900.

New Hotfoil-EHS Catalog Available for Download

Electric Heating Systems, Inc. (EHS), established in 1994 in Robbinsville, NJ, is a designer and supplier of turnkey, permanent low temperature heating systems for the electric power and tank fabricating industries. Later, this division's name was changed to Hotfoil, and the EHS division began manufacturing ceramic mat (pad) heaters, power consoles, and accessories for the heat treating industry.

Hotfoil-EHS is now a major manufacturer and producer of standard and custom designed industrial heat treating products with an exhaustive inventory including custom control panels, heat treating power consoles, cables and splitters, temperature recorders, thermocouple attachment units and pin guns.

Rely on Experienced Welding and Heating Applications Experts for Improved Outcome and Efficiency

Product Experts
Work with the manufacturer's experts for better outcomes
When it comes to selecting the right equipment for welding and industrial heating jobs, projects and tasks are best completed and accomplished through the proper application of the right resources. There exists an access point to high level technical knowledge and assistance that can be easily tapped and brought to bear on your successful task or project completion. The manufacturer's own internal experts.
 
Manufacturers provide services that may help you save time and cost, while also achieving a better outcome for the entire project. Consider a few elements the technical sale rep brings to your project:
  • Product Knowledge: Product managers and sales support personnel will be current on product offerings, proper application, and capabilities. They also have information regarding what products may be obsolete in the near future. This is an information source at a level not generally accessible to the public via the Internet.
  • Experience: As a project engineer, you may be treading on fresh ground regarding some aspects of your current assignment. There can be real benefit in connecting to a source with past exposure to your current issue. 
  • Access: Through the manufacturer's internal applications people, you may be able to establish a connection to “behind the scenes” information not publicly available. The people at the manufacturer can provide answers to your application questions.
Certainly, any solutions proposed are likely to be based upon the products sold by the manufacturer. That is where considering and evaluating the benefits of any proposed solutions become part of achieving the best project outcome.

Develop a professional, mutually beneficial relationship with the manufacturer's technical sales team, and don't be shy to develop a professional and trusting relationship. Their success is tied to your success and they are eager to help you.

Electrostatic Precipitator and Bag House Hopper Heaters Prevent Fly Ash Production Problems

hopper heaters for power plants
Coal fired power plants must manage fly ash properly.
Coal fired power plants in the United States require the use of electrostatic precipitators or bag houses to filter out very fine fly ash particulate incorporated in the flue gas. The ash is collected as the flue gas passes through filter bags or by large electrodes, and then falls into collection hoppers.

As the hot fly ash cools, condensate on the hopper walls can form. The mixture of dry, sulfur rich fly ash and water is very problematic, so it's very important to keep condensation from forming in the collection hoppers. The mixture of water and fly ash can cause clogging (or “pluggage”) in the throat of the hopper,  and more importantly, the residual sulphur in the flue gas will combine with the condensate to form sulphuric acid. The suluric acid attacks the hopper walls from the inside causing corrosion, weakening the walls and creating significant (and costly) maintenance issues over time.

hopper heaters for power plants
Fly ash hopper with heaters.
Efficient and continuous fly ash removal is critical for all coal fired power plants. Collection hoppers are an integral part of the removal process. Pluggage or inoperable hoppers are a known issue to engineers and maintenance crews. The constant maintenance and excess of down time seriously hinder a plant’s ability to manage the fly ash production rate. Slower fly ash production means limiting energy production and efficiency. A power plant’s electricity production is directly proportional with its coal combustion rate which, in turn, directly effects the fly ash production rate. Plant maintenance personnel usually attempt to remedy ash system failures in real time by deactivating the affected hopper while continuing to generate power and ash. In some situations (to prevent boilers shutdowns) ash will be dumped on the floor, requiring costly clean up.

The evacuation and management of fly ash is much easier when the ash is kept hot. One of the most common ways to maintain elevated fly ash and hopper temperature are electric hopper heaters attached to the external hopper walls. Hopper heaters play a very important role in the removal of fly ash from precipitators and bag filter hoppers by keeping the hopper temperatures operating above the flue gas acid dew point. The hopper heater’s sole function is to preheat the hopper and the internal environment to prevent the formation of moisture and the resulting clumping of fly ash and development of sulphuric acid.

hopper heaters for power plants
Flexible heating element used on hopper throat.
Hopper heaters are designed for the dirty, high vibration environment of a power plant. They provide the optimum watt density for proper conduction through the hopper wall and for uniform heating. The are available in square, rectangular, and trapezoidal shapes to accommodate any hopper design. Ancillary flexible heating blankets are available for poke tubes, man-ways, and cylindrical throats.

The use of electric hopper heaters on electrostatic precipitator and bag house fly ash collection systems is a time proven, effective way to prevent condensate formation and the resulting clumping and corrosive acids in hoppers, thus facilitating a better opportunity for uninterrupted fly ash production.

For more information, contact:

Hotfoil-EHS, Inc.
2960 East State Street Ext.
Hamilton, NJ 08619
Phone # 609.588.0900
Fax # 609.588.8333
Email: dap@hotfoilehs.com
www.hotfoilehs.com

Freeze Protection for Coal Handling Systems

coal system heating
Coal stored outdoors on the stockpile or delivered by unit train or barges picks up moisture from rain and snow. When this wet or frozen coal is conveyed, it inevitably comes into contact with the plate steel of the various hoppers and chutes within the coal handling system. During winter, this plate steel is below freezing for extended periods.

When wet or frozen coal encounters steel at sub freezing temperatures an instantaneous bond is formed. This bond causes immediate and often catastrophic blockage of the hopper and chutes. The bond and resultant blockage is so severe that pneumatic drilling equipment and explosives are often required to free up the system.

This problem, known as FLASH FREEZING, is extremely inconvenient and very costly. Several cases are documented where utility and industrial boilers have been shut down due to blocked conveying systems.

The document below describes effective electric heating systems for coal handling freeze protection.