Friday, August 16, 2013
THERMAL
FLUID, HOT WATER and STEAM
All three
have advantages and all of them also do have disadvantages. Fortunately the
three systems do not have the same disadvantages; therefore you will surely
find the most suitable system to fulfill your heat transfer needs. The
following list is not complete, such a list does not exist, but it may be
guidance for those who have to consider a new installation.
THERMAL FLUID OR THERMAL OIL
Advantages
Transfers heat at high temperature and low pressure.
No danger of freezing when the plant stops in the wintertime.
Corrosion minimized.
The only possible heating medium for higher temperatures, for example, asphalts cargos.
Low maintenance costs.
Simple operation starts and stops.
Transfers heat at high temperature and low pressure.
No danger of freezing when the plant stops in the wintertime.
Corrosion minimized.
The only possible heating medium for higher temperatures, for example, asphalts cargos.
Low maintenance costs.
Simple operation starts and stops.
Disadvantages
Huge quantities of thermal oil to be pumped due to low heat transfer value.
Liquid flow heat control is complicated and expensive.
Risk of discoloring when heating vegetable oil.
Risk of high temperature corrosion when heating acids in chemical carriers.
The high temperature minimizes the heat recovery from the exhaust gas heat recovering.
The thermal oil is expensive and it has to be replaced frequently.
The staff usually lacks skills to handle a tube leakage in a thermal heat oil furnace.
Huge quantities of thermal oil to be pumped due to low heat transfer value.
Liquid flow heat control is complicated and expensive.
Risk of discoloring when heating vegetable oil.
Risk of high temperature corrosion when heating acids in chemical carriers.
The high temperature minimizes the heat recovery from the exhaust gas heat recovering.
The thermal oil is expensive and it has to be replaced frequently.
The staff usually lacks skills to handle a tube leakage in a thermal heat oil furnace.
HOT WATER
Advantages
Simpler plants at low temperature, e.g., lower than the water boiling point.
Closed system, continuous water treatment not required.
Simpler plants at low temperature, e.g., lower than the water boiling point.
Closed system, continuous water treatment not required.
Disadvantages
Complicated and expensive pressure control when the temperature is higher than the water boiling point.
Relatively large quantities of water to be pumped.
Liquid flow, heat control is complicated and expensive.
Complicated and expensive pressure control when the temperature is higher than the water boiling point.
Relatively large quantities of water to be pumped.
Liquid flow, heat control is complicated and expensive.
STEAM
Advantages
Transfers huge quantities of heat with comparatively small quantities of steam and water.
Lesser expensive heat exchangers.
Steam flow and heat control are simple.
Use of steam atomized burner is possible.
Use of steam soot blowing is possible.
Steam can also be used for various cleaning purposes.
The steam can also be used to produce power.
Transfers huge quantities of heat with comparatively small quantities of steam and water.
Lesser expensive heat exchangers.
Steam flow and heat control are simple.
Use of steam atomized burner is possible.
Use of steam soot blowing is possible.
Steam can also be used for various cleaning purposes.
The steam can also be used to produce power.
Disadvantages
Requires continuous chemical treatment of the water.
Skilled operators required.
Requires continuous chemical treatment of the water.
Skilled operators required.
Repeatability
The value equal to or below which the absolute difference between two single tests results tested by the same operator, on the same apparatus at the same laboratory, may be expected to lie with a probability of 95%.
The value equal to or below which the absolute difference between two single tests results tested by the same operator, on the same apparatus at the same laboratory, may be expected to lie with a probability of 95%.
Reproducibility
The value equal to or below which the absolute difference between two single tests obtained by different operators, on different apparatuses at different laboratories, may be expected to lie with a probability of 95%.
The value equal to or below which the absolute difference between two single tests obtained by different operators, on different apparatuses at different laboratories, may be expected to lie with a probability of 95%.
Acceptability
When single results are obtained in two laboratories and their difference is less than or equal to the reproducibility, the two results shall be considered as acceptable and their average, rather than either one separately, shall be considered as the estimated value of the tested property.
If the two results differ by more than the reproducibility, both shall be considered suspect.
When single results are obtained in two laboratories and their difference is less than or equal to the reproducibility, the two results shall be considered as acceptable and their average, rather than either one separately, shall be considered as the estimated value of the tested property.
If the two results differ by more than the reproducibility, both shall be considered suspect.
