Prevent Bulk Material Flash Freezing in Hoppers and Chutes

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. 

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. 

Heat Treatment Controllers

ICE STAR manufactures fully digital heat precise and reliable treatment controllers. The ICE STAR controllers ISQ and ISC have from 6 to 12 controlling thermocouple's and up to 36 monitoring thermocouple's. More measurement points are available by connecting up to 14 controllers to each other wirelessly or with cables. The controllers are designed for any kind of heat treatment consoles and furnaces, and can be mounted inside or to front panel. Hotfoil-EHS is the North America representative for ICE STAR.

For more information, visit https://hotfoilehs/icestar or call 609.588.0900.

Common Types of Process Heating Systems and Equipment

External Electric Vessel Heater

In all process heating systems, energy is transferred to the material to be treated. Direct heating methods generate heat within the material (e.g., microwave, induction, or controlled exothermic reaction), whereas indirect methods transfer energy from a heat source to the material by conduction, convection, radiation, or a combination of these functions. In most processes, an enclosure is needed to isolate the heating process and the environment from each other. Functions of the enclosure include, but are not restricted to, the containment of radiation (e.g., microwave or infrared), the confinement of combustion gases and volatiles, the containment of the material itself, the control of the atmosphere surrounding the material, and combinations thereof.

Common industrial process heating systems fall in one of the following categories:

Large heat treated parts - still red-hot.

• Fuel-based process heating systems 
• Electric-based process heating systems 
• Steam-based process heating systems 
• Other process heating systems, including heat recovery, heat exchange systems, and fluid heating systems. 

The choice of the energy source depends on the availability, cost, and efficiency; and, in direct heating systems, the compatibility of the exhaust gases with the material to be heated. Hybrid systems use a combination of process heat systems by using different energy sources, or different heating methods with the same energy source.

Hotfoil-EHS are skilled experts in a wide variety of process heating systems design and fabrication. Contact them at 609-588-0900 or visit their website at http://www.hotfoilehs.com.

Large, Custom Heat Treat Furnace Fabrication

The video below demonstrates the erection of a 16' x 16' x 62' heat treat furnace built out of a 6x6 I-Beam skeletal structure with 11 gauge steel skin. Full size doors, two per end, will allow the furnace to heat loads using it's full volume. The furnace is equipped with eight 3-Million BTU burners, one at either end and 3 down each side, to circulate the air. Four dampers are included, two at each end. It will move back and forth on a rail system by (16) 10" crane wheels. A hydraulic system will act to lift the furnace 3" in the air off the hearth. This will allow the furnace to move freely and without damaging the insulation on the bottom seals. It will be controlled via a remote HMI screen with full SCADA capabilities.

For more information, visit http://www.hotfoilehs.com or call 609.588.0900.

Custom Mobile Heat Treating Trucks

Hotfoil-EHS designs and manufactures custom mobile rigs for remote heat treatment applications.

Custom designs include a variety of generator sizes, power consoles, interior workspaces and layouts, air conditioning, and easy access to all electrical components. For more information, visit http://www.hotfoilehs.com or call 609-588-0900.

Basics of Heat Treating

Interior view of heat treating furnace.

Heat treating refers to the heating and cooling operations performed on metal work-pieces to change their mechanical properties, their metallurgical structure, or their residual stress state.

Heat treating includes stress-relief treating, normalizing, annealing, austenitizing, hardening, quenching, tempering, martempering, austempering, and cold treating. Annealing, as an example, involves heating a metallic material to, and holding it at, a suitable temperature, followed by furnace cooling at an appropriate rate. Steel castings may be annealed to facilitate cold working or machining, to improve mechanical or electrical properties, or to promote dimensional stability.  Steel vessels, girders, pipes, and structures are heat treated prior to, and after welding to improve weld quality and strength.

Gas fired furnace used for heat treating.

Heat treating is performed in conventional furnaces, salt baths, or fluidized-bed furnaces. The basic conventional furnace consists of an insulated chamber with an external reinforced steel shell, a heating system for the chamber, and one or more access doors to the heated chamber.

Heating systems are direct fired or indirect heated. With direct-fired furnace equipment, work being processed is directly exposed to the products of combustion, generally referred to as flue products. Gas- and oil-fired furnaces are the most common types of heat treating equipment. Indirect heating is performed in electrically heated furnaces and radiant-tube-heated furnaces with gas-fired tubes, oil-fired tubes, or electrically heated tubes.

Industrial Process Heating: Electric and Fuel Based

Electric heater used on industrial hopper throat.

Process heating operations supply thermal energy to transform materials like metal, plastic, rubber, limestone (cement), glass, ceramics, and biomass into a wide variety of industrial and consumer products. Industrial heating processes include drying, heat treating, curing and forming, calcining, smelting, and other operations. Examples of process heating systems include furnaces, ovens, dryers, heaters, and kilns. Many of these systems are mature technologies used ubiquitously throughout manufacturing. Process heating is used to raise or maintain the temperature of substances involved in the manufacturing process, such as the use of heat to melt scrap in electric arc furnaces to make steel, to separate components of crude oil in petroleum refining, to dry paint in automobile manufacturing, or to process food for packaging.

Electricity-based process heating systems transform materials through direct and indirect processes. For example, electric current is applied directly to suitable materials to achieve direct resistance heating; alternatively, high-frequency energy can be inductively coupled to suitable materials to achieve indirect heating. Electricity-based process heating systems are used for heating, drying, curing, melting, and forming. Examples of electricity-based process heating technologies include electric arc furnace technology, infrared radiation, induction heating, radio frequency drying, laser heating, and microwave processing.

Gas burners for process heating.

Fuel-based process heating systems generate heat by combusting solid, liquid, or gaseous fuels, then transferring the heat directly or indirectly to the material. Hot combustion gases are either placed in direct contact with the material (i.e., direct heating via convection) or routed through radiant burner tubes or panels that rely on radiant heat transfer to keep the gases separate from the material (i.e., indirect heating). Examples of fuel-based process heating equipment include furnaces, ovens, kilns, melters, and high-temperature generators.

For information on any industrial heating application, contact Hotfoil-EHS at 609.588.0900 or visit http://www.hotfoilehs.com.