Showing posts with label STEAM. Show all posts
THERMAL FLUIDS
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.
Tag :
STEAM,
THERMAL FLUID
CLASSIFICATION AND TYPES OF BOILERS
INTRODUCTION
1) KNOW THE NEED FOR STEAM ON A MOTOR VESSEL.
2) KNOW THE PRINCIPLES INVOLVED IN HEAT TRANSFER AND IN GENERATING STEAM IN A BOILER.
3) KNOW THE VARIOUS WAYS THE BOILERS CAN BE CLASSIFIED.
4) KNOW THE BASIC CONSTRUCTIONAL FEATURES OF SOME
OF THE POPULAR BOILERS USED.
OF THE POPULAR BOILERS USED.
USE OF STEAM
1) HEATING DUTIES: ME FUEL OIL HEATER, PURIFIER HEATER, OIL
TANK HEATING, CARGO HEATING, AIR CONDITIONING & HEATING PLANT, CALORIFIER,
GALLEY SUPPLY, SEA-CHESTS, TRACER LINES FOR PIPELINE HEATING ETC.
2) RUN TURBINE GENERATORS
3) RUN CARGO PUMP TURBINES IN TANKERS
4) DRIVE STEAM DRIVEN DECK MACHINERY LIKE WINCHES ETC. OPERATE
BILGE, STRIPPING AND OTHER STEAM DRIVEN PUMPS DRIVE BOILER FEED PUMP TURBINES
5) EVAPORATOR/FRESH WATER GENERATOR HEATING MEDIA
6) TANK WASHING IN TANKER SHIPS AND GENERAL CLEANING FOR BOILER SOOT BLOWING AND FOR THE STEAM ATOMISED BURNERS
7) FIRE FIGHTING AS USED IN STEAM SMOTHERING SYSTEM
8) MAIN ENGINE JACKET F.W. PREHEATER AND LUB OIL SUMP AND DRAIN TANKS
9) USE IN THE WASTE OIL, INCINERATOR, SLOP TANKS
10) USE AS A STEAM EJECTOR MEDIA FOR EJECTOR PUMPS AND VACUUM DEVICES WATER GENERATOR HEATING MEDIA
TYPES OF BOILERS
1) MAIN BOILER- PROPULSION OF THE VESSEL
2) AUXILIARY BOILER-HEATING OF HEAVY FUEL OIL USING A STEAM
HEATER, NECESSARY FOR PROPULSION WOULD QUALIFY THE SUPPLYING BOILER TO BE
REFERRED TO AS AN
AUXILIARY BOILER.
AUXILIARY BOILER.
3) TANK BOILER- A BOILER WITH LARGE WATER CARRYING CAPACITY
WHERE THE SHELL IS BEING USED AS THE PRESSURE VESSEL. MOST LOW PRESSURE
AUXILIARY BOILERS WILL COME INTO THIS CATEGORY.
4) EXHAUST GAS BOILER- BOILER OPERATED BY HOT GAS FROM ENGINE
OR OTHER EXHAUST GAS SOURCES.
5) DRUM TYPE BOILER-WATER TUBE BOILERS EMPLOYING STEAM AND
WATER DRUMS. THEY ARE ALSO KNOWN AS BENT TUBE TYPE BOILERS.
6) PACKAGE BOILER -FULLY AUTOMATIC, LOW CAPACITY BOILERS
PACKAGED INSIDE A BOX TYPE CASING, CAPABLE OF QUICK STEAM PRODUCTION AND
FLEXIBLE IN BEING POSITIONED ANYWHERE; COULD BE COIL TYPE OR FIRE TUBE TYPE.
SMOKE TUBE & WATER TUBE BOILERS
PRINCIPLE OF HEAT TRANSFER IN BOILERS
LIMITING THE STRESS
MAX WORKING PRESS. = MAX STRESS X 2 X WALL THICKNESS/DIAMETER
THEREFORE TANK TYPE BOILER MAX PRESS LIMITED TO 17.5 BAR
COMPENSATING PADS
POSITION OF MANHOLES
COMPENSATING RING
SUPPORTING FLAT SURFACE
SUNROD CHS
MIURA Z - BOILER
WATER TUBE BOILER
BLUE: THE DOWNCOMERS LEAD THE WATER FROM THE STEAM DRUM TO
THE WATER DRUM AND THE WATERWALLS
HEADERS.
HEADERS.
RED AND BLUE: THE EVAPORATION TUBES AND THE WATER WALLS LEAD
THE WATER AND STEAM EMULSION BACK TO
THE STEAM DRUM.
THE STEAM DRUM.
RED: THE STEAM PASSES THROUGH THE SUPERHEATER BEFORE IT
LEAVES THE BOILER FOR THE CONSUMERS.
KEEP SUPERHEATER VENT OPEN AND MAINTAIN FLOW TO PREVENT
OVERHEATING.