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Electrical Tank Container Heating Systems
South Africa and Sub-Sahara
With the electrical tank container heating systems, eltherm developed a real alternative to heating with steam and Glycol and created some new options for applications. The eltherm product range for electrical heat tracing systems combines high-quality heating cables and accessories with individually designed systems. As an engineering company with its own manufacturing site, eltherm advises container manufacturers from the planning phase on. These manufacturers have relied for many years on the know-how and innovative strength of eltherm. eltherm ensure that all requirements of the container industry are fulfilled by coordinating with the tank manufacturer during the design process to make certain that the heat tracing system is specifically tailored to each container requirement. When faced with complicated and difficult specifications the container manufacturer and sponsor prefer to rely on the experience of the eltherm engineers.
Advantages of the eltherm Tank Container Heating Systems:
Even with damage of one heating cable there are no cold zones on the container
High chemical resistance of the applied heating cables
Low weight, thereby less loading loss and additional consumption
Repairing and maintaining can be carried out quick and easy
Efficient heat distribution
Flexible cables with small bending radius
Various resistances are available, so the transformer is not needed
Low power output W/m prevents container walls from overheating
The automotive industry, machine construction and plant construction require more and more temperature sensitive chemicals. So it is increasingly necessary to transport these chemicals safe way whilst maintaining the product characteristics. Mostly tank containers, SWAP containers, road tanks and IBC’s (Intermediate Bulk Containers) are used. Sensitive chemicals have high requirements for secure transportation.
Electrical Heat Tracing for MDI-tank Containers: Temperature Accuracy up to +/- 1 °C
In one case eltherm engineers successfully faced the challenge of transportation of MDI (Methylene-Diphenyl-Diisocyanate). The task was: heating of 20’ Iso tank containers up to 43° C, with only a temperature variation of the product from +/- 1 K. The engineers also had to consider that on worldwide transports the power supply range can vary between 380 und 440 V. Additionally, the complete control system had to be protected against voltage peaks, that can occur by using power supply from the board network of a container ship or a ferry. A complete record of the product temperature without gaps over the whole transportation cycle must also be provided.
To meet these high requirements the eltherm engineers made several temperature experiments on prototypes. The knowledge that could be gained out of these tests was integrated during the solution finding process. It showed, that for heating the whole tank up to the minimum filling height the eltherm fluoropolymer-insulated heating cables Type ELKM-AG-L are the best choice. In addition to the cable choice, also the way of positioning the cables and the installation play an important role. The especially developed installations technique by eltherm on the one hand makes sure that the required temperature accuracy can be reached. On the other hand it assures a consistent heating of the whole container surface, even if one of the cables is broken by mechanical damage. The Pt100 sensors measure the product temperature for each heating circuit and also the temperature of the heating cable. So you can make sure that even if there is a fault there will not be undesired temperature rises.
The eltherm tank container heating systems are all delivered with complete control systems made of vibration-resistant components in a suitable stainless steel housing. As MDI generally is not unloaded by the bottom valve but over fittings on the spill box, a separate heating for the spill box is also needed to maintain the temperature of the valve and to guarantee its function. This heating was of course also considered by the eltherm engineers and delivered. With some applications also the syphon pipe has to be heated. The heating will be placed in a double casing tube, which has to be produced by the container manufacturer according to the requirements of eltherm. When the heating is operated autarkic without any fixed power supply, an attached generator is switched on and off by the control of the heating system. The proof without gaps of the required temperature during the complete transportation is assured by so called data loggers. If the measurement results are within the tolerances, this also makes sure that the customer accepts the delivery. The electrical tank container heating system of eltherm has not only revolutionized the common tank container heatings, it also allows custom-made solutions even for highly sensitive and difficult temperature requirements.
Electrical Heat Tracing of High-temperature Tank Containers
For transportation of highly viscous materials of the chemical and petrochemical industry, suitable and worldwide applicable transport containers are needed. Electrically heated 20’ Iso tank containers, SWAP-containers and road tanker are the best fitting solution. Especially in these cases there are high requirements on the electrical heating. High heater output with as low as possible heat loss, short time preheating of the empty tanks before filling, as well as resistance of the heating system against filling temperatures up to 260 °C were demanded here. In general these tank containers are operated without generators, so a power reserve has to be installed, to be able to heat the tank content over several hours if needed.
Because of the temperature range the electrical controllers can be operated with a hysteresis of +/- 5 K. No problem for the eltherm engineers. As the used eltherm heating cables are manufactured in the own production site, our engineers have been able to develop a special tank container heating cable for this special temperature range. So the requirements of power and high temperature could be fulfilled. Power output up to 18 kW with power supply range between 380 and 440 V have to be realized with a temperature maintenance up to 210 °C. To reduce heat loss to a minimum our engineers developed in cooperation with insulation companies a multilayer insulation, which allows, together with the heat tracing, an energy efficient usage of the systems. Redundant temperature sensors and the eltherm typical installation of the heating cables make sure, that even if there is any mechanical damage, the heating can be used without any cold areas on the tank. Roundabout 80 % of the tank surface are heated consistently. The bottom valves of these kind of tanks cool down especially fast. So it is necessary to install a Mikanit heating element on the discharge pipe and the valve as a separate heating circuit. A custom-made heating jacket is used as thermal insulation. This jacket can be removed for cleaning and put on again without any problems. To be able to document and see the energy consumption during heating an operation hour counter is installed for each heating circuit. This tank container heating system, developed by eltherm, provides a perfect solution which is characterized by cost effectiveness and also convenience.
Heating of Chocolate Containers
After mixing the ingredients needed for production of chocolate, the mixture is conched*. After conching the chocolate is quite liquid and not really suitable for eating. Because of the increasing internationalization of the leading confectionery producers, it is more and more necessary to transport primary products like fat, oil and cocoa butter as well as finished products like chocolate mass between the production sites for further processing without quality loss. The liquid form for transportation of bigger quantities is the most economically advantageous way. To make sure that the chocolate does not loose its characteristic taste or gets hard, a heating of the container is needed. Here the worldwide standardized means of transportation are applied, like e.g. 20’ Iso tank containers, SWAP-containers, road tanker and IBCs.
The task for eltherm:
Pre-heating of the tank before filling
Temperature maintenance during storage and transportation
Maintenance temperature freely programmable between 40 and 70 °C
Temperature tolerance: +/- 2 °C
Supply voltage 380 – 440 V
Assure that there are no temperature rises to avoid changes in product characteristics
Avoid undergoing of minimum nominal value to make sure that tanks can be emptied completely
The eltherm engineers developed a best suitable solution. The tank container surface was heated constantly with the eltherm fluoropolymer-insulated heating cable ELKM-AG-L up to the fill capacity of 80%. Particular attention was paid to compensation of heat losses on „cold bridges“ like tank suspension. By the eltherm specific installation technique of the heating cables a constant heating is assured even when there is any damage on the heating cables. Of course eltherm again supplied the complete control system and generators for power supply without interruption. The documentation without gaps throughout the whole transportation cycle is an important requirement of the quality management system and is assured by data loggers. At eltherm the complete engineering, design, calculation and installation on site are included in the scope of supply of this kind of projects.
* (heating up to 90 °C and stirring constantly)
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