At high and low ambient temperatures, heat insulated storage tanks are an important measure for security of supply to industrial installations as well as to professional gas stations when housing temperature-sensitive media.
Pour, Melting and Flash Points of Operating Materials
Many media such as fuel and mineral oil as well as specific chemical compounds and/or heavy fuel oil and paraffin cause problems at high or low ambient temperatures. The industry is used to install aboveground storage tanks within or outside buildings on open spaces.
These tanks will be usually thermo-insulated in freestanding installations. Most of time, this is not required in buildings. Unless the medium’s pour point exceeds 30° C, including but not limited to heavy fuel oil or paraffin.
In wintertime, tanks containing medium and installed outside are very often confronted with sub-zero temperatures. It is a prerequisite to install high-quality thermo-insulation in storage tanks containing temperature-sensitive media.
If needed, the insulation will be enhanced by tank heating to keep the storage medium above the pour point. They operate electrically or using warm water coils.
In case of traditional gas stations, it was customary to solve this temperature issue by installing underground tanks. This guaranteed media temperature of approx. 8 °C within the storage tank below the soil cover even in the wintertime.
Today, these soil-covered tanks are no longer up-to-date for reasons of environmental protection as well as modern logistical requirements.
Reasons of Environmental Protection
You can control the buried storage tank only from inside. The anti-corrosion protection is not visible from outside. However, aboveground tanks need to be installed visible from all sides. The same is true for underground supply lines of storage tanks (German Water Resources Act). One consolation is the dual wall construction of underground storage tanks and pipes. However, this does not enable a one hundred per cent external control.
Modern Logistic Requirements
The processing technologies of liquid media as well as the provision of liquid media at site are subject to constantly changing requirements. Take the supply of urea to vehicles. It is difficult to anticipate the fluctuating fuel demand in the individual regions equipped with underground storage tank systems. It is tedious, time-consuming, expensive and much too risky in light of the gradual change to other types of drive such as electric cars.
Aboveground storage tanks including but not limited to storage tank containers with insulated versions create a professional solution.
- Fast setup and installation
- State-of-the-art, conformity to German Water Resource Act, easy to control system components
- Fast, easy switch to larger or smaller units, if needed
- Fast and easy replacement of these units by new generation components
Petrol and Gasoline
Petrol is a standard fuel for petrol engines used in all common vehicles such as boats. Petrol has a pour point of -45 °C and a flash point of +35 °C. The major problem of aboveground storage of petrol is the transition of petrol to the gaseous phase at 35 °C. Petrol may evaporate into the atmosphere via the tank ventilation aperture.
A tank can easily reach a temperature of more than 50 °C at the tank cover when exposed to direct sunlight. The simplest protective measure is a sun shield. The most helpful and better measure constitutes the complete thermo-insulation of the storage tanks.
Diesel is the standard fuel for large engines. Many cars and almost all buses and trucks use this kind of fuel. Its melting and freezing point is already at -20 °C. The problem with diesel is that it will separate paraffin at this temperature. A high-quality tank system will counter this risk by reliable heating coils. It is particularly important to drain the diesel fuel.
Inside the shell, non-insulated aboveground tanks constantly show condensation of small amounts of water from the air to the temperature change of day and night. This condensation collects in the bottom of the tank. In the boundary layer between condensation and diesel, colonies of special microbes form at temperatures exceeding 20 °C. This microbiological phenomenon is also known as diesel plague. This process can be slowed downs and/or prevented by a thermo-insulated tank.
Kerosene and Air Field Fuel
The same problem applies to this kind of fuel as to diesel. Only the issue of condensation has a more serious significance. Aviation fuel has to be absolutely free of water. In addition, a thermo-insulated tank would be good answer from the technological perspective.
Urea is an increasingly important operating material for diesel vehicles. It is fed to the diesel engine’s exhaust and provides for a reduction of pollutant emissions within the exhaust gas catalytic converter. It is non-combustible, but highly aggressive and decomposes everything too long in contact with. As a result, it is particularly challenging to store urea. Urea freezes already at -11 °C and loses significantly in viscosity at temperatures of slightly more than 0 °C and tends to flocculation. This flocculation can clog vital supply lines and severely damage the engine. Again, we recommend thermo-insulation and an electric tank heating.
Thermo-insulated storage tank should be complemented by consistent pipe insulation. This pipe insulation ensures that any thermo-insulated tank would have as little as possible cold bridges during filling and emptying. The particular advantage of the pipe insulation is both the heat and cold insulation. It improves the operating ability of the mobile fuel station in any case. However, a thermo-insulated tank has natural limits: During prolonged cold periods, the cold will penetrate to the inner of the tank sooner or later. As a result, further measures must be taken.
A Heated Tank guarantees Operational Safety
If the mobile service station was installed at a site with expected particularly long-lasting cold periods, a heated tank will be the answer to the challenge. An integrated tank heating keeps the operating substances in liquid state and ready for pick-up. This is made possible by a sophisticated sensor system. It ensures that the operating materials remain liquid, but using as little energy as possible. As described, problems begin at cold temperatures around at +5 °C. In particular, urea can start the freezing process at this temperature. Urea is particularly critical, since the resulting crystals are very square-edged. In case of diesel, the aforementioned separation of paraffin is a major problem. This may be prevented by adding a certain quantity of petrol and by drainage. However, both methods are difficult to implement technically. To ensure complete operational safety of mobile and independent fuel stations, a heated tank is the easiest solution.
The application of heated hoses is also useful for operation material such as diesel and urea when particularly confronted with cold. The filling hoses of a mobile fuel station are not self-emptying, but remain filled with operating materials after the first-time usage. Even if you use a heated tank, the source of heat will not be able to reach the operating material in the hose. Tank hoses are the remedy to be installed in an isolated chamber. However, maximum operational safety is the core requirement for an exposed tank system. A heated tank equipped with reliable heating coils and respectively heated fittings ensures operational standby of a fuel station at low outdoor temperatures.
Deflecting Heat by Design
The protection of operating materials against heat is significantly easier to implement. The natural day-night-rhythm in combination with a high-performance insulation ensure that the interior temperature would never reach critical values. A thermo-insulated storage tank may also deflect natural maximum outside temperatures with no additional cooling. However, the installation at a very hot site requires increased subsequent maintenance. Most of all, junctions such as sleeves, hoses and valves are under stress by particular sudden changes between hot and cold, resulting in possible leaks. To prevent this from happening, you urgently need excellent service and continuous monitoring of connections and fittings.
Krampitz for Maximum Security of Supply
If you want to meet any of the technical challenges, Krampitz will offer the ideal package from a single source: design and development of storage tanks for each climate zone. Individual equipment according to the customer’s desire and comprehensive customer service maximize the operational readiness of mobile tank systems at each point on earth.