Heat Loss
Trace heating systems are widely used wherever stored and transported materials are can not alone be protected by an insulation against heat loss.
Each medium must be provided with a combination of trace heating and insulation to reach or maintain its optimal temperature
With a temperature differenve between inside the pipe to the ambient temperature outside the insulation, a heat loss constantly flow from the pipe(blue arrows).
Is the heater output (red arrow) equal or larger than the heat loss or higher the system is able to maintain or increase its temperature.
the heat loss of pipes is calculate withg this equation:
Qv= (2 * pi * lambda * (Th - Tmin)) / (ln * (D/d)) ( Here you can online calculate heat losses in a table)
| Qv | heat loss(W/m) |
| lambda | thermal conductivity(W/mK) |
| Th | maintain temperature (°C) |
| Tmin | minimum ambient temperature (worst case °C) |
| ln | natural logarithms |
| D | pip diameter with
insulation(mm) ( pipe diamter+ 2 x insulation thickness) |
| d | outer pipe diamter without insualtion(mm) |
the formula to calculte the heat loss of a tank it similar:
Qv= (A * lambda * (Th - Tmin)) / s
Qv= total heat loss(W)
A = total tank surface ( m²)
s = insulation thickness (Meter!)
(all other see above)
^To Top
Insulation
As
can be easy seen from the above-mentioned formulas and presentation,
the thermal insulation of the plants is a very essential
part for the fulfillment of the requirements for the accompanying
heating.
In Germany, detailed description of the execution of
thermal insulation for heating systems in the accompanying worksheet
AGI Q103 to find.
See at your local installation regulations/recommendations for doing
insulation of electrical trace heating
Auswahl des Dämmmaterials
- thermal properties (thermal conductivity and temperature dependence of this value at very high temperatures)
- mechanical properties
- chemische compatibilityand resistance
- Feuchtebeständigkeit
- Feuerbeständigkeit
- Kosten
Beim
Aufbau der Dämmung gibt
es verschiedene Varianten:
Source: VE25 des VIK (german trace heating council for hazardous areas)
When choosing the insulation for the underlying weather barrier, the following important considerations should be made:
Types of trace heating
Depending on the application one can find 3 basic types of
trace heating:
Frostprotection
(
as a special type of temperature maintenance)
avoid frost damages at objects, frostleakages and avoids pricess damages
Temperature maintenance
hereby the temperature within the pipe/tank is higher than the ambient temperature(e.g. 30°C), which mwanss
that a deadlock of the process the appilcation must be heated, to stay at the right process temperature.
So e.g. the ease of flow can be maintained or get better.
(Oil, gas etc)
Rise of
temperature
Here you find different kind of appilcations as:
- heating up of an empty pipe or tankAufheizen der Rohrleitung/Tanks leer
- heating up of a filled pipe or tank
At heating process nparticularly on must take of the duration
of the heating up process. For short heating times or heating of
flowing
media often the transfer surface of the pipe is too small or a
very
high power density is required. Here one often switch to other
heating systems (e.g. heat exchanger) and includes a
temperature
maintenance with electricla trace heating.
Industrial applications
Here some examples of industry-specific applications. Since
the
electrical trace heating is very flexible and easy to use, it has in
almost all sectors of the industry prevailed.
Installation,
maintenance, and also helped reliability of the electrical trace
heating on all important processes of the industry to a large boom that
still continues.
In addition, the controllability for the
commercial application of the electrical trace heating, especially
under consideration of the cost of operation, this type of heating is
very
lucrative.
Even if other options are available, the
above-mentioned reasons lead to the use of controlled and
maintenance-free electrical trace heating.
| Industrial branch | Application |
| Oil and gas | lubricant, gas oil, lubricant grease, additives |
| petro chemistry | oil, grease, additives, naphta |
| Chemistry | acids, bases,adhesives, fertilizer |
| Pharmacy | wax, stearids, emulsions |
| Cosmetics | wax, Oil, grease, plant extracts |
| power stations | ashes,sulfid, bases |
| Food & beverages | broweries, molasses, sugar, fat, oil, butter |
commercial construction application
Also in commercial construction applications yolu can find different
types of applications for electrical trace heating.
- Frostprotection
These are tubes and safety equipment (eg sprinkler systems), similar to the industrial application protected against frost damage.
This is impoartant for pipe in air piope in unhested rooms (underground parkings) and not frost free in earth pipes.
A very special application of frostprotection and temperature maintenance is pond heating - Roof-
and gutter deicing
AEven with change of our world woide climate this appolicatoion gain more and more importance. Specialist say that theat we will have not more more snow but hevier snow in future (more moisture snow)
By this portection of people against snow from a roof or iciles get relevant.
Together with a special kind of monotoring system the economic and saftey aspects of the system are brought together. - Hot
water systems
For this application two different apsects occurs very imprtant:
Ad 1: for large warm water pipe contstructions the danger of leginella grows rapidly within warm standig water. This can lead to a legionella desease espially for weakend people (hospitals, senoior residences). There the electrical trace heating is uesed to heat up for a short time the totaslpipe systen up to 65°C to decontaminate the pipe system. This is possible with the right trace heating material and the swtich on during reduced operation times
Ad 2: to have warm water at your water tap instantly one normally uese circulation systems. This kind of comfort needs two pipe systems, which causes two times a heat loss. To avoid that and to reduce costs during installation and operation trace heating system are build on that warm water pipes. It is a n economici, safe and reliable kind to have 'green' warm water instantly
Installation
An expert made and in according to the design data installed insulation is esential for a correct working electrical trace heating
The Assembly can only begin when the pipeline fully assembled and pressure tested. Before beginning the assembly should meet the requirements .
The best transfer of the heating or heating of the tube is stretched. spiralizing convolute the heating cable should be avoided, since it is a higher dange of damage and failures (spiral distance must be kept accurately, mechanical damage in the upper part of the tube. Etc..)
Here are some hints for the layers
To compensate for higher heat losses on flanges, valves and other
fittings additional line lengths are designed for such
locations.
This can be done by direct
wrapping the additional length around that build in. Often, however,
the need, to maintain the heated work pieces
(eg valves) must be taken in account. The techinc of build up
'heated baskets' around that instruments and fix the tapes on that.
makes it easier to re-open the heating system durung maintenance work
