January 26, 1953 Bokaro Thermal power Station Bokaro is the biggest power station in India. Pari of the capital coat of Bokaro Steam Power Station estimated at RS 13.8 crores Law been met by a World Bank loan tumnmting to 18.5 million dollars, or Rs 9 crores, Bokaro Station will obtain coal from a part of Bermo seam, Kargalli colliery, which has been leased by DVC. This seam consists of low grade coal for which there is normally no market. Ash content is high, varying from 26 to 31 per cent. India's deposits of high grade coal are limited and require to be conserved for iron and steel industry and Bokaro helps tills conservation. Bokaro Station is connected to the DVC transmission network covering 375 miles of 132 kv line, 32 milas of 66 kv and 96 miles of 13 kv lines, serving an area of about 25,000 square miles. AS a result of a recent load survey of the DVC area total prospective maximum demand on DVC system was asseftsed at 282,000 kw, 459.000 kw and 550.000 kw during next live, ten and fifteen years. Bokaro Steam Station order placed on international General Electric Company on February 23, 1949, ground broken at site December 29, 1949, Station opened on February 21, 1913. OKARO, unlike Tilaiya, does explained, though the result, in peak load demand for electricity B not constitute a first step in view of the existing demand for in the valley and the availability of the scheme for taming the Damo- power in the valley, has been entirely power from hydro-electric installa­ dar river. It does constitute, how­ tions. The mining belt, a major ever, a milestone in the country's consumer, has its peak demand in progress. Situated on the river monsoon for pumping out water Konar just below where it meets from the mines just when the the Bokaro river, the power sta­ hydro-electric stations are in a posi­ tion has been located close to the tion to give peak production. In coal mine from which it gets its the following seasons it is necessary coal supply. Bokaro is 50 miles to conserve water for purposes of from Hazaribag and 233 miles irrigation and generation of elec­ from Calcutta by road. The power tricity has necessarily to be stepped station has been designed for base down and here the thermal station load operation for about 37 weeks at Bokaro comes so very handy. of the off-monsoon period and as a The boilers at the power station peak load station for the remain­ arc designed to use inferior grade ing 15 weeks in the monsoon. The coal which is obtained by open cut later period of high load will pro­ mining of the Burmo seam at Kar- vide an opportunity for general gali about 5 miles from the power overhaul and inspection of machi­ station. The colliery belongs to nery. Messrs Bokaro and Ramgarh Ltd Designed for ultimate capacity of and was under lease to the GIP 200,000 kw, three units of 50,000 railway. It has now been sub-leas­ kw each have already been set up, ed to DVC for a period of 35 years. of which the first goes into opera­ The mining will be mechanised tion today and the other two will and coal transported by aerial rope­ follow soon- by June next, accord­ way with a capacity of 150/200 tons ing to present expectations. per hour. The colliery is also con­ Why a thermal station should nected to Bokaro power station by conic first in a multi-purpose pro­ rail and road, to be utilised in the ject which is primarily intended to event of a breakdown of the rope­ control and utilise water power, way. The leased area contains, it one may naturally ask, though is estimated, about 17 million tons after the bitter experience" of Bom­ of coal, of which the following is bay, even a layman will hardly an analysis: need much persuasion to believe Moisture 1.16 per cent that a grid system depending exclu­ Volatile matter 20.2b .. sively on rain-fed rivers or lakes is M Fixed Carbon 53.15 „ „ not the best possible arrangement. Ash 26.6 Admitting the necessity for a ther­ Calorific Value mal station for balanced supply (dry basis) 11,200 BTU and distribution of electricity Fusion Point of through different seasons of the Ash 2/282 deg. F year, the 'priority that Bokaro enjoy­ ed and the fact that it happens to happy. There is a fortunate and very The entire power station was be completed first, Still needs to be favourable co-relation between the designed by the International Gene- 211 February 21, 1953 THE ECONOMIC WEEKLY ral Electric Company who also tages of generally higher efficiency; factors are of importance In supplied the main plant and equip­ due to mote complete combustion India," ment while the designing and super­ less ash residue, more rapid pick­ vision of const ruction was done by up or dropping of load, and better AUTOMATIC CONTROL the Kuljian Corporation of USA. temperature control over wide Incorporating the most modern Coal is fed from the ropeway load limits. practice, units are designed to ope­ bunker or rail track hoppers The selection of steam pressure rate normally on automatic control by means of reciprocating feeders. and temperature for the boilers and under constant as well as varying The tilling of the coal into buckets turbines, higher than had previ- load conditions. The turbine gov­ at the mine and its discharge into impractical. Pulverized coal fired erning system is actuated hydrau- the bunkers at the power house is lically by oil pressure generated by done automatically. Alter passing a centrifugal pump on the turbine over a magnetic pulley, coal is fed shaft. In general, other mecha­ into a crusher capable of reducing nical control systems are operated the run of mine coal into three- by compressed air. fourths of an inch. From here it The combustion control system is conveyed either to the bunker on automatically distribute the effect the top of the boilers or to a stock­ of fluctuating requirements of steam pile in the coal yard, A drag- by the turbine-alternator on the scraper piles coal to a height of two boilers equally, controls the 26 ft and also packs it in such a fuel iced of each boiler to main­ manner as to eliminate spontane­ tain the desired steam pressure at ous combustion. The yard holds any load, controls the furnace draft stock to last 2½ months. A reverse maintaining a negative pressure drag bucket reclaims the coal from under normal operating conditions, the stock pile when necessary. It controls the forced draft to main­ can be dumped into reclaim hop­ tain the fuel-air ratio, controls the pers and led back into the con­ pulverizer mill temperature so as to veyor system, avoid lire hazards or inefficient grinding due to wet coal. STEAM GENERATING UNITS Other controls provide control of The plant has been laid down steam leaving the superheater, feed on the unit system of each gene­ water, water levels in feed water rating set with two boilers and each heater and hot wells. boiler is supplied by two coal bun­ Main station controls are central­ kers. For the three units all the six ised and control boards arc fitted steam generating units are alike. with indicating and recording Steam generating units are of instruments, automatic and manual 300,000 lbs per hour capacity, pul­ control devices, alarms and push­ verized coal fired, and consist of buttons. two drum, bent tube boiler and a water-cooled furnace manufactured OUTDOOR SWITCHGEAR by the Combustion Engineering The use of forced-oil, water- Super-heater Inc., USA, and sup­ cooling for the 65,000 KVA main plies steam at 895 psig with total transformers resulted in lower cost, temperature of 910 F. The boilers size and weight, and made possible are provided with forced and transport over the railway from induced draft fans and air pre- Calcutta. The 138-KV outdoor heaters. Each steam generator is substation is remotely controlled equipped with four burners. Two from the duplex switchboard. A pulverizers are provided per boiler, main and transfer bus arrangement one feeds the two lower burners is provided. The main bus is scc- and the other feeds the two upper tionalised by disconnecting switches burners. Each pulverizer is sized so that one section of bus can be to cany 80 per cent of the full removed from service for mainten­ load. The station has been design­ ance and repair. A bus tie breaker ed for pulverized fuel only, but is also provided so that any line heavy duty lighting-off" equipment [ breaker may be taken out of ser­ has been supplied to act as pilot vice for routine maintenance or torches in case of coal failure. ously been employed in India, fol­ repair. The disconnecting switches The present-day practice where lowed the most conservative prac­ are motor operated and are inter­ large steam turbine-generators are tice in the United States for tur­ locked with their respective breakers involved makes use almost univer­ bines of this capacity. 'The advan­ to ensure proper operation. sally of pulverized firing for coal tage in using higher pressures and Altogether 11 — 138-K V, 1200 burning in boilers, due primarily to temperatures lies in the improved amp., 3500 MVA pneumatically the lower initial investment per station efficiency, reduced unit cost operated outdoor type oil circuit kilowatt of plant capacity realised of power generation, reduced breakers have been used.