This article is a continuation of the previous article titled the “Heating and Storing Asphalt Part 1”. It continues on the general theme of talking about the role of industrial process heating and heaters in depth at the storing and transportation of asphalt in factories and before they can be put to use.

Heating Systems

Primarily there are two types of heating systems in play at the asphalt plants. One is the fuel heating systems while the other is the electric heater heating system. Both of these systems are poles apart from one another in terms of functionality, characteristics and benefits.

The first system of heating represents an old system. One system that has been in play for a good number of years and one that is heavily reliant of heavy fuels such as diesel and gasoline. These heating systems typically make use of fires and heat produced as a result of it to heat and increases or maintains the temperature of the asphalt.

This system doesn’t take the heating head on and will typically heat the liquid asphalt from outside the container. The most important thing to take into account in this regard is maintenance of temperature may be a weakling of this method. Heating systems like these may find it difficult to accurately judge the temperature of the asphalt. Also powering them up using fuel to come up to their optimum heat producing capacity may take some time.

Another problem that is likely to hinder their use these heating systems on a large scale is the increasing importance being given to the protection of environment. One of the primary features of environmental protection is to save up on fossil fuels. Fuel and that too heavy fuel are the primary source of powering up such heating systems. Not will lack of such fuel can cause a downfall in their fortunes, also increasing emissions of harmful substances from the burning of heavy fuels can result in imminent threats being posed to the environment.

To make sure that the heating requirements of the asphalt industry are fulfilled without having to compromise on the protection of environment or prevention of combustive fuels being used. This is done by the use of second heating systems being used in the asphalt industry. These systems make use of high powered electric heaters. The electric heater makes use of heating elements to make produce the necessary heat that is required. There are many a reasons why the second heating system should be used over the first. The first reason in that regard can be that it is a new technology. It has been designed to fit in with the changing consumer demands and industrial technologies and applications.

Secondly and perhaps most importantly, the fact asphalt needs constant heating at a certain temperature makes electric heaters standout from the first heating system. While the first heating system may have been able to heat a colder lower temperature asphalt to a high temperature, its effectiveness at maintaining temperature has been called into question more time than one. In stark contrast, the secondary heating system made up of electric heaters is able to ensure that the asphalt temperature is maintained. The problem with maintenance of asphalt temperature and warmth depends primarily on the checks on the temperature drops. With electric heaters that task is usually done by a sensor that is attached to the control panels. This control panel has a bearing over the electric heaters. As the temperature drops, the sensors can notify the control panels which start the electric heaters.

As mentioned in the previous part sometimes asphalts that may not be used for long can be left to cool down. In the event that they are needed, the electric heater heating systems will be able to heat them faster than the other heaters. These heating systems make use of heating elements that are run on electricity and are designed to warm up quickly.

Another major difference between the two kinds of heating systems is the way they go about with the actual heating. Industrial process heating with electric heaters typically use direct heating methods. The heating elements come in contact with the product and directly heat it. This is makes sure that there is little or no heat loss since most of the produced is directly added to the product itself.

Direct Fired Tanks

A direct fired tank is an important heating system. This is typically used when either the storage heating requirements are inadequate or the asphalt needs to be heated before it is used or when the distance to transport the asphalt is more than the amount of time the asphalt can keep its heat intact. These direct fired tanks are typically installed with proper insulation to ensure relatively little loss of heat. These tanks are typically attached to either an immersion or any other type of electric heater or it has a burner installed in at the bottom of the tank.

Yet with the emphasis on environment and safety of vehicles that transport bitumen, the use of electric heaters on the direct fired tanks is more of a norm. The use of electric heaters and the insulation of the tank mean that the tank has a high thermal efficiency. A truck in its basic composition, this heater is easy to move around and maintain and there are only so many parts that have to be used.

The use of direct fired tanks is best for small asphalt plants. The need for industrial process heating in these plants will typically not be in such high demand since there may be only one or two storage tanks for asphalt. Not needing heat for other components of the plant.

Despite having a plethora of advantages, some of them are not well suited for larger PMAC plants. The larger the plant, the greater the need for heating is typically the notion put into play. In addition to that there is need for the heater to be able to heat other subsidiary products that complete the assortment of asphalt. Heating other components is a task almost impossible for direct fired tanks. They can only do so with the help of multiple scavenger heating coils or booster heaters etc.

One disadvantage of the direct fired tanks that make use of burners is that there is very little space for the heat to affect the asphalt. This means that typically the recovery rate of temperature in such direct heaters is 1 to 3 degree F per hour.

Accordingly direct fired tanks that make use of immersion heaters have a greater surface are to heat. The heating element in immersed in the asphalt allowing for it to be heated thoroughly from within without any bit of heat loss.

People in the asphalt industry that are looking to buy and make use of them, it is important that they realize the potential of these heaters in terms of temperature maintenance instead of temperature increase in bitumen products. Temperature increase is a job that is best left to large storage containers that have powerful electric heaters with strong heating elements attached to them. In a direct fired tank, both the place of heating, the method of heating being used and the amount of asphalt that can be heated will all be inadequate.

Heating fuels

Even today heating systems in some asphalt heating and storage factories are heavily reliant on usage of heavy fuels. These heating systems work with a large number of fuel varieties. Typically the fuel usage of these heaters has been compared to that of aggregate dryers. Usually both can work in tandem where the dryer uses more of the fuel than the heating systems however.

One of the overriding factor as mentioned above for heating systems is that the emissions of these heating fuels can be harmful for the air we breathe in and the environment that is integral to our survival on earth. These fuels will typically produce high amounts of emission, however now; there has been a shift with the remaining fuel powered heaters moving away from such high on emission fuels.

Most of these fuels used are typically heavy and will often need to have a pre heating of their done to be ready for use in these heaters.

Heaters to Pre Heat Fuel oil

Some firms of asphalt continue to use heavy fuels in their fuel powered heating systems. One of the drawbacks of this is that fuel powered heaters typically take longer to come up to their full heat since they are slow starters. This late appearance can possibly prove to be catastrophic for asphalt, which can quickly lose its temperature and alter its state to become a solid.

Heaters with Features Best Utilized in the Asphalt Industry

Electric Circulation Heaters

• Thermal insulated vessels
• Special wattages, sizes and materials are available whenever you need them
• Units are available with larger vessels and heavier flanges
• Can be supplied with stainless steel parts and special design terminal boxes for heat    protection Custom unit sizes
• Standard sizes: 1.25” NPT Screw Plug size to 14” diameter
• Steel or stainless vessels fitted with 150 lb./300 lbs/ 600lbs/ 2000 lbs. psi flanges
• Custom-designed to meet your specifications
• Use in high temperature conditions.
• Compact
• Clean
• Insulated upon request
• Installation of the product is easier.
• Durable
• Highly energy efficient
• Provide fast response and even heat distribution
• Easy mounting support
• Suitable to general purpose terminal enclosures, NEMA 7, NEMA 4X NEMA 7, and unsafe or explosion proof locations
• Reduce heat loss from the vessel
• Provide maximum dielectric strength
• Compatible with standard industry piping and safety standards
• Protect and prevent from thermal insulation
• Provide greater wattage in a smaller heater bundle
• Designed and built for safety
• Works in conjunction with Control Panels

Immersion Heaters

• The heaters have  standard 1-inch openings of conduit
• Custom-designed to meet your specifications.
• The elements can be of a variety of diameters, such as 0.375”, 0.475”, 0.315” and 0.430”
• Special sizes, wattage are available upon request CSA and UL approved
• Lightweight
• Sheath materials:

• Steel riser made up of stainless steel
• Steel riser made from stainless high quality steel

• All models are moisture proof.
• No new holes need to be drilled
• Portable heater which makes it easy to remove and easier to install
• Low and fast maintenance
• Operation from 1 to 3 phase
• Optimum levels of heat transfer
• Built solidly
• Designed for safety
• Uniformity in Temperature
• Able to withstand the effects of moisture
• Resistant from the effects of corrosion and Oxidation
• Durable

Pipe Heaters

• Single element ratings: 4-20 kW
• Quick heat up time & easily replaceable
• Outside diameters: 1 7/8’’ and 2 ¾’’
• Lengths: 60-320’’ (5-26 ft)
• Pipe Surface: 3-12 W/In2
• Equipped with high density electrical ceramic insulating supports
• Voltages: 240, 480 and 600V, 3 PHASE
• Used in horizontal 2’’ or 3’’ schedule 40 NPS pipe
• Special ratings and lengths available upon request
• Can be bent in a vertical plane on at least 12’’ radius
• Easy installation
• Very flexible
• Heavy gauge bus bars
• Heavy gauge resistance wire
• Long service life
• Uniform heat distribution
• Very long – 40 ft or greater
• Equipped with a continuous support bar that ensures proper rigidity

Boiler Heaters

• Moisture and contaminant resistant
• Available special sizes, wattage’s, and materials upon request
• Heating units are designed in a way that meets your industrial needs.
• Maintenance is easier
• Easy to install
• Replacement Boiler Flange Heaters – TYPE FL
• Energy efficient
• Square or round steel flange types
• Broad variety of sizes for different applications

Conclusion

In conclusion it is fair to say that the importance of the asphalt industry in the development of infrastructure in the world is clear. As important as asphalt is to the transport system, the same is the level of importance of electric heaters and process heating in this industry.

For more insight into process heating in different industries, read the Wattco Blog, look through our heating industry case studies, or contact one of our experts today for a quote on some of the many high grade industrial heating elements offered in our product catalog.