Coal Handling process. Brief description about the activities carried out

Coal Handling process

1. Power systems instrumentation Group presentation assignment BEE 4105 PRESENTATION MEMBER REG. NO ATIBUNI YOFAT 2020/A/KEE/0039/G/F SSEMBALIRWA DENIS 2020/A/KEE/0034/G/F WAFULA MOSES 2020/A/KEE/0040/G/F ATUKUNZIRE JOVIAS 2020/A/KEE/0675/F OKELLO THOMAS 2020/A/KEE/1800/G/F NAGAGO BRIDGET 2020/A/KEE/0689/F SAMANYA JOSEPH 2020/A/KEE/2154/F AGUMA MEMORY 2020/A/KEE/0786/F ARINDE FRANCIS 2020/A/KEE/0908/F MUSAU CONNEL 2020/A/KEE/0696/F

2. Discuss the fuels (preparation and auxiliaries) and fuel system of coal-fired steam power plants. Fuels are materials that are burnt to produce a large amount of heat energy. Fossil fuels are used to heat water in order to form the steam which powers the turbine to generate electrical energy. Different types of fuels are used in different boilers for steam generation. The different fuels include solid fuels, liquid fuels and gaseous fuels. However, solid fuels are the most commonly used fuels in steam power plants (coal fired steam power plants).

3. Coal Preparation When the coal delivered is in the form of big lumps and it is not of proper size, the preparation (sizing) of coal can be achieved by crushers, breakers, sizers, driers and magnetic separators. The arrangement of a coal handling plant is shown as shown below.

4. Coa l preparation continued………. Coal is crushed on a crusher to proper size as per the requirement of the boiler. This crushed coal is fed to the vibrating screen for getting the required size coal. Magnetic separators are provided to separate magnetic materials from the coal. Then, this coal is weighed in weigh feeder and stored in a hopper called as storage bin for use in the boiler.

5. Fuel auxiliaries. Conveyor belt system. Conveyor belt is used for feeding coal into the boiler. Numbers of belts are used for coal transportation from coal stock yard up to the boiler bunker. A conveyor belt is an endless rubberized flat belt moving between pulleys . It consists of a various pulleys , idler arrangements and a suitable belt tensioning arrangement systems Feeders. This is an equipment use in coal handling plant to control or regulate the rate of coal flow from a bin of hopper. The feeder is used in conjunction with conveyors, crushers and vibrating screens. They precisely meter the flow of pulverized coal into the boiler furnace .

6. Fuel auxiliaries continued. Coal crusher Coal obtained from coal minds is not sized as requirement for the boiler. Bigger size coal can not be used in the boiler So its required to size the coal properly before feeding it to the boiler. This is done at the crusher. Screen . Crushed coal from the crusher is screened to segregate the over size and required size coal. Screen is used for this.

7. Fuel auxiliaries continued Fans. They provide air for combustion that is to say; primary air for initial ignition and secondary air for complete burning within the furnace. Bucket Elevators It s used convey materials vertically rather than horizontally. The elevator has a series of buckets attached to an endless loop of belt or chain

8. The fuel system. Handling of solid fuel : Coal handling plant, Based on the design of the boiler, different grade coals are used in different boilers. The coal is handled in a coal handling plant. The various steps involved in coal handling are as follows; Coal delivery. Unloading. Preparation.

9. CONT………… Transfer. Outdoor storage. Covered storage. In plant handling. Weighing and measuring. Feeding the coal into a furnace.

10. Flow chart of a fuel handling system.

11. CONT…. Coal Delivery. The coal from the supply points is delivered by ships or boats to power stations situated near to sea or river whereas coal is supplied by rail or trucks to the power stations which are situated away from sea or river. The transportation of coal by trucks is used if the railway facilities are not available.

12. CONT….. Unloading. The type of equipment to be used for unloading the coal received at the power station depends on how coal is received at the power station. If coal is delivered by trucks, there is no need of unloading device as the trucks may dump the coal to the outdoor storage. Coal is easily handled if the lift trucks with scoop are used. In case the coal is brought by railway wagons, ships or boats, the unloading may be done by car shakes, rotary car dumpers, cranes, grab buckets and coal accelerators. Rotary car dumpers although costly are quite efficient for unloading closed wagons.

13. CONT….. Preparation When the coal delivered is in the form of big lumps and it is not of proper size, the preparation (sizing) of coal can be achieved by crushers, breakers, sizers, driers and magnetic separators.

14. Cont … Transfer. After preparation, coal is transferred to the dead storage by means of the following systems; Belt conveyors, Screw conveyors, Bucket elevators, Grab bucket elevators, Skip hoists, Flight conveyor.

15. CONT… Coal Storage Purpose of coal storage. Insurance from failure of normal operating supplies to arrive Permits some choice of date of purchase, allowing the purchaser to the advantage of seasonal market conditions. It is a matter of protection against coal strikes, failure of the transportation system and general coal shortages.

16. Cont … Coal storage can be done in two types; live storage (boiler room storage) and dead storage. Live storage. This is the storage from which coal may be withdrawn to supply combustion equipment with little or no remanding. This storage consists of about 24 to 30 hours of coal requirements of the plant and is usually a covered storage in the plant near the boiler furnace. The live storage can be provided with bunkers and coal bins.

17. Cont … Bunkers are enough capacity to store the requisite of coal; from bunkers, coal is transferred to the boiler grates. Dead storage. This storage is intended for future use. Mainly is for longer period of time, and its also a mandatory to keep a backup of fuel for a specified amount of days depending on the reputation of the company and its connectivity.

18. Cont … In plant handling. From the dead storage the coal is brought to covered storage (Live storage) (bins or bunkers). In plant handling may include the equipment such as belt conveyors, screw conveyors, bucket elevators etc. to transfer the coal. Weigh Lorries hoppers and automatic scales are used to record the quantity of coal delivered to the furnace.

19. Cont … A cylindrical bunker is shown in below .

20. Cont …. Coal weighing methods. Weigh Lorries, hoppers and automatic scales are used to weigh the quantity coal. The commonly used methods to weigh the coal are as follows: i . Mechanical ii. Pneumatic iii. Electronic.

21. Cont … The Mechanical method works on a suitable lever system mounted on knife edges and bearings connected to a resistance in the form of a spring of pendulum. The pneumatic weighs use a pneumatic transmitter weight head and the corresponding air pressure determined by the load applied. The electronic weighing machines make use of load cells that produce voltage signals proportional to the load applied.

22. Cont … The important factors considered in selecting fuel handling systems are as follows: i . Plant flue rate ii. Plant location in respect to fuel shipping iii. Storage area available.