Definition of Boilers Boiler Vessel that heats water to become hot water or steam At atmospheric pressure water volume increases 1,600 times Hot water or steam used to transfer heat to a process

Types of Boilers Fire Tube Boiler Water Tube Boiler Packaged Boiler Fluidized Bed (FBC) Boiler Stoker Fired Boiler Pulverized Fuel Boiler Waste Heat Boiler Thermic Fluid Heater (not a boiler!)

Boilers for Various Applications

Boilers Babcock and Wilcox Benson Cochran Cornish Lamont Lancashire Stirling Velox

Boilers based on Firing 1. Fire Tube Boiler is Relatively small steam capacities (12,000 kg/hour) Low to medium steam pressures (18 kg/cm2) Operates with oil, gas or solid fuels To begin with, we will look at the fire tube boiler: This is generally used for relatively small steam capacities and at low to medium steam pressures. The steam rates for fire tube boilers are up to 12,000 kg/hour with pressures of 18 kg/cm2. Fire tube boilers can operate on oil, gas or solid fuels. The figure illustrates how a fire tube boiler works. The fuel is burned and heats up the water to steam which is turn channeled to the process. Today, most fire tube boiler are in a packaged construction for all fuels. (Light Rail Transit Association)

Type of Boilers 2. Water Tube Boiler is Used for high steam demand and pressure requirements Capacity range of 4,500 – 120,000 kg/hour Combustion efficiency enhanced by induced draft provisions Lower tolerance for water quality and needs water treatment plant In a water tube boiler, boiler feed water flows through the tubes and enters the boiler drum. The circulated water is heated by the combustion gases and converted into steam at the vapour space in the drum. These boilers are selected when the steam demand as well as steam pressure requirements are high as in the case of process cum power boiler / power boilers. Most modern water boiler tube designs are within the capacity range 4,500 – 120,000 kg/hour of steam, at very high pressures. Many water tube boilers are of “packaged” construction if oil and /or gas are to be used as fuel. Solid fuel fired water tube designs are available but packaged designs are less common. The features of water tube boilers are: Forced, induced and balanced draft provisions help to improve combustion efficiency. Less tolerance for water quality calls for water treatment plant. Higher thermal efficiency levels are possible (Your Dictionary.com)

Assessment of a Boiler Heat Balance Balancing total energy entering a boiler against the energy that leaves the boiler in different forms 12.7 % BOILER Heat loss due to dry flue gas 8.1 % Heat loss due to steam in flue gas 100.0 % 1.7 % Heat loss due to moisture in fuel Heat balance is an attempt to balance the total energy that enters a boiler against the energy that leaves it. This figure illustrates the different typical losses that occurs while generating steam. (Question) Does anyone have any suggestions of what the two major heat losses are? (Discussion) (Click once and answer reveals) They are dry fly gas that represents a heat loss of 12.7% and heat loss as a result of steam in the flue gas of 8.1%. (Click once for other heat losses to appear) Other heat losses are due to moisture in the fuel and in the air, as well as unburnts in residue and radiation. (Click once) This leaves 73.8% of heat that goes to steam. Fuel 0.3 % Heat loss due to moisture in air 2.4 % Heat loss due to un-burnts in residue 1.0 % Heat loss due to radiation & other unaccounted loss 73.8 % 73.8 % Heat in Steam

Mountings and Accessories Fitting and devices which are necessary for the safety and control are knows as boiler mountings Fitting or devices which are provided to increase the efficiency of the boiler and help in the smooth working of the plant are knows as boiler accessories

Fittings - Safety Water level indicators Safety valves Combined high steam and low water safety valve Fusible plug

Fittings - Control Pressure gauge Junction or stop valve Feed check valve Blow-off cock Man hole and Mud Box