Fossil Fuel Supply for India's Coal-fired Power Plants

Related Vendors

DÜPERTHAL Sicherheitstechnik GmbH & Co. KG

Glatt Ingenieurtechnik GmbH

EDL Anlagenbau Gesellschaft mbH

Tata Consulting Engineers

Challenges in System Design

Coal size plays a very important role in the design of transportation, unloading and handling systems. In the earlier decades all the utilities were burning only Indian coal. When indigenous coal is used, the coal size can be as large as 400 millimetres to 1 metre. Because of this, there are lot of challenges to be faced by the utilities and the designers.

Typically, the large size lumps block free flow of smaller size particles at the track hopper/receiving travelling hoppers in ship unloading systems and damage the discharge chutes and their liners, conveyor belts and the other equipment as well. The problems are compounded by the presence of large sized boulders. The difficulties faced are mainly in receiving, screening, crushing, design of chutes, etc. Coal handling systems have to be provided with lot of features to avoid all these problems which increases the cost significantly. Hence when the import regulations were liberalized, utilities started opting for importing of coal.

Imported coal is sized with the top size varying between 50 to 100 millimetres. This has reduced the preparation and handling problems to a large extent. 50-millimetre size coal is acceptable in coal pulverizing mills supplied by overseas suppliers and the need for crushing has been eliminated. In the on going Ultra Mega Power Project (UMPPs) at Mundra, this concept has been adopted. If the size of the “as received coal” can be restricted to 50 millimetres, raw coal itself can be stacked instead of the crushed coal, even if coal has to be reduced to -25 millimetres.

Gallery

Gallery with 7 images

India has large reserves of coal which have not yet been fully explored and hence the usage of domestic coal has to continue. Therefore many utilities including some of the future UMPPs will still have to use Indian coal. In such cases, to obviate the problems associated with handling large size coal, the size of the “as received” coal has to be restricted to say 100 millimetres at the mine itself.

This has already been adopted in some cases. In mine mouth stations, the size of the as received coal has been reduced to almost 100 millimetres with mining activity being contracted. In the 2x600MW project of Essar at Mahan (now under engineering) this concept has been adopted since the first stage, crushing is expected to be at the mines itself.

Techno Economic Studies

In power projects the main consideration is the tariff or the rate at which electricity is supplied to the public. Generally the tariff is fixed. One of the main inputs to this cost is the landed cost of coal. Landed cost of coal comprises the ex-mines cost and the supply cost. The two together give the landed cost at site. Supply cost should take into account the cost of all the infrastructural facilities, operating and other project related costs. Since the landed cost plays an extremely crucial role, a detailed techno economic feasibility study is most important.

In a feasibility study, all technically feasible alternatives have to be evaluated along with the cost for each of the alternatives and the technically best alternative with the least landed cost has to be selected. The landed cost with such a technically best alternative has to be considered for calculation of the tariff and required corrections if any in the selected alternative to meet the tariff requirements, have to be carried out.

Conclusions

• Project requirements are to be considered before planning any unloading and transportation system.

• Various solutions are available for transportation and unloading systems.

• Sea transport for transportation over long distances will continue to be the main stay for future also

• New trends are emerging. However for these to get implemented in future lot of efforts is required in the on going projects considering the cost and efficacy of such trends.

• Developments in design procedures and setting international standards have to get further impetus for pipe conveyors.

• Techno economic feasibility studies have to be carried out before adopting a suitable alternative with the least landed cost of coal to ensure the electricity tariff is within the limits set for it.

* B.V. Sambashivan is Managing Director Tata Consulting Engineers, India, Tel. +91 80/6638-4300, E-Mail: bvsambashivan@tce.co.in

(ID:35459490)