Winter Operation Challenges of Storage Tanks
In the cold season, many regions of the world face challenges with storing liquid in tanks, especially outdoors or in unheated spaces. Cable heating can solve this problem: evenly warming the tank helps maintain the required temperature. A proper calculation of the tank heating system is necessary to select a cable with optimal specifications and to lay it in the most efficient configuration.
If a liquid is stored in a tank before winter, its temperature can be maintained through a combination of heating and thermal insulation. An optimally designed system should include both components. Insulation alone is insufficient, while heating alone is inefficient due to significant heat losses.
In a tank that is not heated during the cold season, various issues may arise:
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Crystallization of the liquid
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Coagulation of particles with sediment formation
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Condensation
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Changes in the physical and chemical properties of the product
Heating is necessary to maintain the required temperature and compensate for heat losses. It is not intended to raise the liquid to a higher temperature. Cable heating is an optimal solution for tanks stored outside heated facilities. It is simple to install and cost-effective to operate.
Calculations
To determine heat losses and calculate the required power of a heating cable, certain calculations must be performed. The following parameters are needed:
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Temperature inside the tank (TiT_iTi) and outside (ToT_oTo)
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Surface area of the tank (SSS)
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Thickness of the insulation layer (ddd)
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Thermal conductivity of the insulation (λ\lambdaλ)
How to calculate the area?
The surface area of a cylinder, which is the shape of the tank, is calculated as:
S=2πR(h+R)
where R is the radius and h is the height of the tank. If the calculation is done for a water supply tank, the area is calculated without the base. The radius is equal to half of the diameter.
How to calculate simple tank heating
P = S * R * ΔT * k, where R = λ / d – thermal resistance of the insulation, ΔT = Ti – To – temperature difference, k = 1.25 – safety factor.Пример расчета
Initial data:
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Ti (internal temperature) = 10°C
To (external temperature) = -20°C
S = 15 m²
d = 0.15 m
λ = 0.05 W/m·°C -
ΔT = 10 - (-20) = 30
R = 0.05 / 0.15 = 0.33
P = 15 * 0.33 * 30 * 1.25 = 185.6
As a result of the calculations, it is clear that a heating cable with a power of 185.6 W will be required.
Important!
To simplify the calculation of tank and reservoir heating, TS LLC recommends using the special calculation software TSCalc. This program allows you to determine the required length of heating cable and its power based on the input data of the heated object.
Cable selection
A tank heating cable system consists of:
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Heating cable
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Junction boxes and tape
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Clamps and brackets
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Boxes with indicator lights
The cable can be of two types: self-regulating or resistive. A resistive cable delivers a constant amount of heat unless a resistor is installed in the control cabinet. The system is equipped with a thermostat and a temperature sensor.
A self-regulating cable contains a semiconductor matrix that allows the heat output to adjust automatically with changes in temperature.
Resistive cables are cheaper, but less efficient and harder to use for precise temperature control. Self-regulating cables are more expensive, but easier and more convenient to operate.
Suggestions for installation
The cable is installed on the surface of the tank. To do this, a supporting structure (mesh, harnesses, welding, or other options) is secured to the tank, and the cable is mounted on it. Installation tape or clamps can be used for fastening. If the tank is not expected to be filled completely, it is recommended to lay the heating cable along the lower part of the tank. The cable should follow a serpentine path, with bends kept within allowable limits.
As a solution that is easy to install and convenient to operate, cable heating has virtually no competitors. It is an ideal option for maintaining the desired temperature of tanks stored outdoors. Our company offers a wide range of heating cable models, and our engineers can help perform calculations to make your system as efficient as possible.
