Presentation on theme: "Industrial Boilers Steam generators Closed vessels made of steel and"— Presentation transcript:
1 Industrial Boilers Steam generators Closed vessels made of steel and used for generation of steamvaporizing watercombustion of fuelseg. coal,coke,oil,wood,saw dust and begesse etc.Steam used for producing power,for industrial process work or for heating proposes.
2 Requirements of a Perfect Steam Boilers Should be absolutely reliable,capable of producing maximum steam at required pressure for minimum of fuel consumption,with minimum attention and minimum initial cost and operating cost.Simple constructionsQuick starting from coldStrong enough against temp. stress & strainsWell design combustion chamberLess floor area, space & light weightBest gauges,safety valves and other mountingsEasily accessible for inspection,cleaning and repairs
3 Classification of Steam Boilers Vertical or HorizontalStationary(Power plant,industrial,central heating and combined power and heating boilers.),Portable,Locomotive or MarineInternally Fired or Externally Fired (Lancashire and Locomotive Boilers)Solid,Liquid or Gas FiredFire(Smoke)Tube:Water is outside the tubes while the hot gases are inside the tubes eg.Vertical,Cochran,Lancashire,Cornish,Locomotives,etc) or Water Tube: Contain a large number of small tubes through which water circulates,the fire and hot gases being outside of the tubes.eg.Babcock and Wilcox, Stirling and High pressure Boilers etc.)
4 Vertical BoilersUsed in small factories,small water supply plants,cranes,excavators,winch engines in mines and on sites of temporary nature such as construction work etc.Required minimum floor space,not required elaborate foundations,and is portable.Cheap,easy to start but inefficient due to large wastage of fuel and less heating surface.Vertical Boilers are:Simple(having one to three cross tubes), fire tubes and water tubes types.
5 Simple Cross tube vertical boiler consists of a cylindrical shell surrounding a cylindrical fire box.heating surface is about 8-10 times the grate area.50% efficiency
6 Cochran BoilerIt is well design of a Vertical multitubular fire tube boilerImprovement over the simple vertical boiler as it provides greater heating surface.Total heating surface area is about times the grate areaEfficiency 70-75%Ranges from 1m dia.X2m high,evaporation 20kg/hr to 3m dia X6m high,evaporation 3000kg/hr.
8 Lancashire BoilerIs horizontal smoke tube boiler size range from a shell 2m diaX6m long to 3m diaX10m longWorking pressure range are up to 20kgf/cm2Ratio of heating surface to grate area is 24-30Efficiency is about 56% without economizer and 75% with economizer.Similar to Cornish boiler,in Lancashire Boiler two flue tubes but in Cornish boiler only one flue tubes are there.
20 Fire tubes Vs water tubes Boilers Fire tubes boilers has a large volume of water,therefore more flexible and can meet the sudden demand of steam without much drop of pressure.Fire tubes boiler is rigid and of simple mechanical construction,so greater reliability and low in first cost.Fire tube boilers can be made in smallest sizes therefore simple to fabricate and transport, occupies less floor space but more height.Due to mostly externally fired water tubes boiler so furnace can be altered considerably to meet the fuel requirements.Water tubes boilers are more readily accessible for cleaning,inspection and repairs,compared to the fire tube boilers.Modern trend is in the favors of water tube boiler due to continuous increase in capacities and steam pressures.
21 Boiler Mountings and Accessories Fitting and devices which are necessary for the safety and control are knows as boiler mountingsFitting 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 which are essential from the safety point of view are as follows,Water level indicatorsSafety valvesCombined high steam and low water safety valveFusible plug
22 Boiler Mountings and Accessories contd…. Fittings which are essential from the control point of view are as follows,Pressure gaugeJunction or stop valveFeed check valveBlow-off cockMan hole and Mud BoxThe important accessories areSuperheaterEconomiserAir-preheaterFeed pump or injector