Coal Storage – Handling in Captive Thermal Power Plants

Coal, a non-renewable combustible black sedimentary rock composed of carbon and hydrocarbons, whose combustible quality can be used for electricity generation. Peat, Lignite, black coal and anthracite are four most common forms of coal. Coal based captive thermal power plants are plants, which makes the use of coal for combustion and generate electricity by virtue of heat generated in combustion of coal. Coal Handling in Coal handling Plants/Unit takes place in following three steps:

• Bunkering of coal
• Unloading of coal
• Stacking of coal

Bunkering and Unloading of coal is done whenever coal mines are far away from power plant. The Transportation mode for coal will be purely dependent on the power plant location, location of coal mines and available methods of transportation. Coal handling including bunkering and unloading, now called as ‘Out-plant Coal Handling’ and handling excluding bunkering and unloading known as ‘In-plant Coal Handling’. During out-plant coal handling, coal quality may get affected as it tends to absorb moisture and oxygen of air. This problem losing coal quality can be eliminated by coal storage.

A large machine known as Stacker or Reclaimer mainly used for bulk storage and inside bulk storage shed facility. As the name suggests, the two main functions of stacker are:

1. Stacking
2. Reclaiming

In Stacking Process, coal stock travel on conveyor rail in horizontal as well as in vertical direction.  Stackers may be used to form two different patterns- ‘cone’ , ‘chevron’ either on one or both sides of stacker. Main motive of coal stacking is to produce efficient industrial outcome from coal by avoiding problems faced in coal stacking like oxidation of coal, spontaneous combustion, self-heating of coal, increase in moisture and many more.

In Reclaiming process, the two modes of operations are performed by stacker.

1. On/Off Mode: In this mode of operation, Material to be reclaimed are not only easy to handle but also it maintains reclaimer efficiency. The material is carried on the belt driven by the constant speed and then discharged to the discharged/feed bin.
2. Direct Mode: In direct mode of operation, it is difficult to handle the material to be reclaimed but this mode gives benefit to eliminate the need of intermediate bins.

Earlier, Stacker/Reclaimer run manually by operators but now due to advancement in technology, their operations are made to run on PLC-based automation, which not only make the operations cost effective but also saves the time to complete operations. This Coal Storage and handling can be done under bulk storage dome (like Coal dome, lignite dome) and horizontal semi circular storage sheds   We, at Hindustan Alcox Limited, satisfy our clients the best available solution in storage and handling of any type of bulk storage.