Classification & Types of Boilers Rajan Bhandari Singapore Maritime Academy 5/9/2019

Introduction Know the need for steam on a motor vessel. Know the principles involved in heat transfer and in generating steam in a boiler. Know the various ways the boilers can be classified. Know the basic constructional features of some of the popular boilers used. 5/9/2019

Overview This is a introductory lecture and explains the use of steam and application of various types of boilers for use on a motor vessel. 5/9/2019

Vocabulary Smoke tube, Fire tube, Tank Type, Drum Type Carnot efficiency 5/9/2019

Use of Steam 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. Run Turbine Generators Run Cargo pump turbines in Tankers Drive steam driven deck machinery like winches etc. Operate bilge, stripping and other steam driven pumps Drive boiler feed pump turbines Evaporator/Fresh water generator heating media 5/9/2019

Use of Steam Tank washing in tanker ships and general cleaning For boiler Soot blowing and for the steam atomised burners Fire fighting as used in steam smothering system Main engine Jacket F.W. preheater and Lub oil sump and drain tanks Use in the waste oil, incinerator, slop tanks Use as a steam ejector media for ejector pumps and vacuum deviceswater generator heating media 5/9/2019

Types of boilers Main Boiler- Propulsion of the vessel 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. 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. Exhaust Gas Boiler- Boiler operated by hot gas from engine or other exhaust gas sources. Drum Type Boiler-Water tube boilers employing steam and water drums. They are also known as bent tube type boilers. 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. 5/9/2019

Smoke tube & Water tube boilers Fire tube concept Shell with fire tubes inside Tank type boiler Water tube concept Drum with fire tubes 5/9/2019

Tank type & Drum type boilers Fire tube concept Shell with fire tubes inside Tank type boiler Water tube concept Drum with fire tubes 5/9/2019

Principle of heat transfer in boilers Radiation Conduction Convection 5/9/2019

Limiting the stress Longitudinal stress = Pressure x diameter 4 x thickness of wall 5/9/2019

Limiting the stress Circumferential stress = Pressure x diameter 2 x thickness of wall 5/9/2019

Maximum working pressure Max working press. = Max stress x 2 x wall thickness diameter Therefore Tank type boiler max press limited to 17.5 bar Fire tube concept Shell with fire tubes inside Tank type boiler Water tube concept Drum with fire tubes 5/9/2019

Compensating pads 5/9/2019

Position of manholes 5/9/2019

Compensating ring 5/9/2019

Supporting flat surface 5/9/2019

Supporting flat surface 5/9/2019

Sunrod CHS 5/9/2019

MIURA Z - Boiler 5/9/2019

Water tube Boiler 5/9/2019

Water and steam flow diagram Blue: the downcomers lead the water from the steam drum to the water drum and the waterwalls headers. Red and blue: the evaporation tubes and the water walls lead the water and steam emulsion back to the steam drum. Red: the steam passes through the superheater before it leaves the boiler for the consumers. 5/9/2019

Boiler with integral super heater Keep superheater vent open and maintain flow to prevent overheating 5/9/2019

Carnot efficiency Carnot's Eff iciency % = (T1 ‑ T2 ) x 100 (T1) Turbo alternator T2 at condenser T1 T2 5/9/2019

Efficient heat exchange Thickness of the tube material reduces its conductivity but it is an important factor in limiting stresses in the material Heat conducted = Difference in temp x area x time thickness of material T1 T2 5/9/2019

Summary Need for steam on a motor vessel. Principles involved in heat transfer and in generating steam in a boiler. Various ways the boilers can be classified. Basic constructional features of some of the popular boilers used. 5/9/2019

Where to Get More Information Morton, Thomas D, Steam Engineering Knowledge for Marine Engineers (1994), Thomas Reed Publications Flanagan, G T H, Marine Boilers Question & Answers (1995) Operation Manuals, Aalborg Boilers Operation Manuals, Miura Boilers Milton, J H and Leach, Roy M, Marine Steam Boilers (1995) 5/9/2019