Material Handling Overview

 Coal Handling Overview at Power Plant

The Coal Handling Overview at Power Plant are following:

figure 1. coal handling system

• Coal Receiving Line/ Incoming System / Stacking System

It’s mean coal from ship is transported to stockpille. Coal received by the coal unloader line, then transferred to conveyor belt. The provided conveyor belt ( 2 unit, C1A and C1B ) are continued to tower 01. Tower is used as the connection between two conveyors, and also as a place for magnetic separator.

Magnetic separator is used to separate metal ( Ferro only ) by passing through coal flow in the operating belt conveyor. This device is aimed to prevent metal damaging the belt conveyor, the trapped metal is stick to belt of magnetic separator and directed to collected metal bin at the end of the 3 meters magnetic separator belt. Magnetic Separator can’t make system trip.

Tower functioned to regulate the direction of coal flow, whether to use conveyor A or B. For example, the coal flow from both conveyor 1A and 1B is collected to hopper and then the  diverter gate ( deflector gate ) towards 2A or 2B decide to be opened or closed. Tower has diverter gate is Tower 2, Tower 6, and Crusher building. The other ones are not have diverter gate. Almost in tower there is Dust Suppresion, to scrap or minimize the amount of dust caused by coal when is transporting. The placement is each towers from tower 1 until 5. There is no dust supresion in both crusher building and tower 6 because of preventing plug in coal silo.

Along conveyor 2, there is a load-cell-digital-belt-scale to check the sum of coal unloaded from the ship. Another scale is located on reclaimer A and B to compare the weight from the previous belt scale. So that we can get information whether the coal spill can be tolerated or else should be taken care of.

The conveyor belt is installed in pair; one is used for operation, the other is used as spare. For special condition when the coal stock should send to silo directly, both of the belt can be used. The capacity of belt conveyor is 1500 ton/h, the normal operation is below 1300 ton/h to prevent spillage of coal and undetected metal in coal flow.

Coal conveyor is driven by motor drive [6.5 x 250 A], connected to gear box and fluid coupling. To prevent belt miss-alignment, there are belt alignment roller along the belt conveyor. Metal wire along the side of belt is provided for emergency tool, this device is called Pull Cord Switch. In case operator finds a metal in coal flow. In such case operator draw the wire to activate the interlocking system or stop the belt operation.

Stacker and reclaimer ( STARE )

This equipment has two function both to stock / receive and to reclaim / deliver coal. Four modes of its operation:

- Operation (O) : normal delivering and receiving process

- Schedule Maintenance (SM) : stopped for predictive maintenance purpose

- Break Down (BD) : stopped for the failure of equipments and accessories

- Idle (I) : stand by mode, ready for normal delivering and receiving operation.

Stare is moved by 8 motor, 4 in left leg and 4 in right leg. There are Rail Calm as safety protection equipment. It is role as the holder between leg of Stare and its rail so the stare is unmoved even something happen in around environment. Safety protection equipments are consist of two kinds, hardware and software. Hardware protection place on 2 m and 300 m of rail counted from north.

Movement of stare is travelling, slewing, and hoisting. These also be called as reclaiming system. When stacking is travelling from north to south, while reclaiming is from south to north.

         The important parts of Stare:

ü  Split Device Þ to control how much coal go to stockpille and go to coal silo ( called also bypass activity ). For example 20 %, its mean coal to silo is 20 % and to stockpille is 80 %.

ü  Collapsable spoon Þ to control when stare is stacking or reclaiming. Close when stacking and open when reclaiming.

ü  Chute wheel Þ placed around bucket wheel , the function is similar with collapsable spoon. Open when stacking and close when reclaiming.

ü  Water Dedusting Þ to decrease the amount of dust from coal when running.

ü  Stockpile overview in display ( Bench ) :

–         Top bench

–         Intermediete bench

–         Bottom bench

• Coal Delivery Line/ Outgoing System / Reclaiming System

The main activity of this system is transporting coal from stock pile to coal silo. After stacked from coal stock pile, the coal distributed to crusher building. In the end of Conveyor 5 A / 5B, there is magnetic separator. After its passing, coal is temporary stored in Susbin. How much coal needed can be adjusted here by regulating its gate. Output from Susbin, coal goes to belt feeder. Then coal flow directly to the vibrating screen. By using spring and unbalanced mass, the screen dynamically separates the coal size. Measure of screen is 2.5 cm x 2.5 cm. The oversized coal go to the crusher. The qualified coal flow to conveyor 6A / 6B directly. In the end both meet again in Conveyor 6A / 6B.

Metal detector is located afterwards, in order to stop the conveyor operating system in case there’s any metal ( all kinds of metal ) slipped among coal. In such case the operator who works in coal control room check the coal flow and separate the detected metal manually. The unwanted metal can damage the pulverizer and another coal processing equipment. Sampling Systems are located in 2 points, in conveyor 2A / 2B and after the metal detector in conveyor 6A / 6B. Sample is needed for coal sampling process executed in laboratory to re-check whether the quality of coal proper compared to its certificate. The sample is automatically took from the coal flow, fall to the sampler bottle. Belt Scale also located here after Sampling system.

From conveyor 6 A and B, the coal distributed to 6 unit of coal silo each unit by using tripper car and tripper gallery. The sequence of filling the coal silo is determined by the coal control room operator regarding to the level of coal inside the silo. For burner coal consumption, 5 coal silos are needed. Another available one is for spare, while the ratio of MCV and LCV is 4:1. The required size for coal burning process inside boiler is 200-mesh grid. 

      Coal Silo Filling Method :

–         Automatically Þ Just adjust set pont ( excample 95 % ). Tripper car will fill silo until reach 95 % and then seek where silo is under 95% level.

–         Manually Þ operator self bring tripper car to silo he want.

Ø  The Parts of Conveyor

1.       Drive, as force service which consist of motor, breaker, fluid coupling ( arrange when starting and regulate rotation ), gear box.

2.       Haed Pully

3.       Tail Pully, here is place of speed sensor

4.       Carrying Roller

5.       Return Roller

Ø  The Protection Equipment in Conveyor

1.   Speed sensor, velocity permitted is 60 m/s until 110 m/s. While in normal operation is about 90 – 95 m/s. The outside of those values will cause trip. To prevent that tragedy, there is necessary needed speed sensor.

2.     Belt misaligment switch

3.     Pull cord switch

4.     Chute plugged switch

5.     Patch limitaton switch