Summary <strong>of</strong> country study – Bangladesh 137 kW 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 6 8 10 12 14 16 18 20 22 Time <strong>of</strong> the Day Figure 3.2 Power generation at the textile mill as a function <strong>of</strong> time Ton <strong>of</strong> Refrigeration 590 570 550 530 510 490 470 450 6 8 10 12 14 16 Chiller-1 Chiller-2 18 20 Time <strong>of</strong> the Day Figure 3.3 Cool<strong>in</strong>g provided by chillers as a function <strong>of</strong> time The management <strong>of</strong> the mills cites several advantages <strong>of</strong> the <strong>cogeneration</strong> plant, such as primary fuel sav<strong>in</strong>gs, reduced energy costs, enhanced reliability <strong>of</strong> power supply, <strong>and</strong> reduced environment pollution. Follow<strong>in</strong>g are the benef<strong>its</strong> from the process side: reduced lapp<strong>in</strong>g, reduced end breakage, improved product quality due to cleaner environment, reduced burnout <strong>of</strong> the motors. Moreover, turnover <strong>of</strong> technical staff has reduced considerably, workers feel less fatigued <strong>and</strong> there is reduced absenteeism. As a result, there is 30 per cent <strong>in</strong>crease <strong>in</strong> overall productivity. The gas eng<strong>in</strong>e generator with vapour absorption chillers is found to be an effective performance enhancement option. The result <strong>of</strong> this specific study should encourage other process <strong>in</strong>dustries to look seriously <strong>in</strong>to the prospects <strong>of</strong> opt<strong>in</strong>g for <strong>cogeneration</strong> <strong>in</strong> their respective plants. This will not only be reward<strong>in</strong>g to them, but also to the country as a whole 22 24 24 2 2 4 4
Summary <strong>of</strong> country study – Bangladesh 138 s<strong>in</strong>ce the <strong>in</strong>digenous energy sources will be exploited more rationally <strong>and</strong> the national power utility would have a lower burden <strong>of</strong> cop<strong>in</strong>g with the ever-<strong>in</strong>creas<strong>in</strong>g power dem<strong>and</strong>. Cogeneration <strong>in</strong> sugar mill There are 15 sugar mills <strong>in</strong> Bangladesh. These mills are owned by the government but controlled <strong>and</strong> managed by 'Bangladesh Sugar <strong>and</strong> Food Industries Corporation (BSFIC)'. Sugarcane required by each mill is collected from <strong>its</strong> surround<strong>in</strong>g areas. The <strong>in</strong>dustry meets the major requirement <strong>of</strong> country's sugar. Sugar mills also produce molasses <strong>and</strong> bagasse, two very important by-products that are used as raw materials <strong>in</strong> distilleries <strong>and</strong> paper <strong>in</strong>dustry respectively. Bagasse is also the ma<strong>in</strong> fuel for sugar mill boilers, produc<strong>in</strong>g steam that is required <strong>in</strong> the manufactur<strong>in</strong>g process <strong>of</strong> the mill. In 1993-94, these mills crushed 2.7 million tons <strong>of</strong> cane, produc<strong>in</strong>g close to a million tons <strong>of</strong> bagasse. Data on <strong>in</strong>stalled capacity, cane crushed, turb<strong>in</strong>e capacity, on-site power generation, power purchased, are shown <strong>in</strong> Table 3.2. Table 3.2 Data <strong>of</strong> sugar mills <strong>in</strong> Bangladesh for the mill<strong>in</strong>g season 1993-94 No Sugar mills Installed capacity Cane crushed Turb<strong>in</strong>e generat<strong>in</strong>g capacity Annual operation Power generated Power purchased (TCD) (ton) kW Days MWh MWh 1 Panchagar 1,016 143,952 2,000 150 2,967 678 2 Thakurgan 1,524 200,213 3,000 148 3,878 538 3 Setabganj 1,250 135,872 4,000 114 3,838 631 4 Shyampur 1,016 125,111 2,000 138 2,897 510 5 Rangpur 1,321 154,421 2,600 131 3,879 462 6 Jaypurhat 2,032 220,294 2,500 136 3,586 1,121 7 Rajshahi 2,000 234,072 3,500 162 5,519 1,462 8 Natore 1,500 263,941 4,000 167 5,972 786 9 North Bengal 1,500 270,979 2,000 166 4,159 1,487 10 Kushtia 1,524 162,325 3,000 130 3,104 855 11 Carew 1,150 185,752 3,000 175 3,446 2,778 12 Mobarakganj 1,500 218,985 2,000 156 1,888 736 13 Faridpur 1,016 171,431 2,000 160 299 648 14 Zeal Bangla 1,016 143,091 2,000 155 3138 739 15 Deshb<strong>and</strong>u 300 16,674 500 67 564 178 Total 19,665 2,647,113 38,100 49,134 13,610 As most sugar mills have similar configurations, one <strong>of</strong> them is described here with more details. This mill has three water tube boilers, each with a steam generat<strong>in</strong>g capacity <strong>of</strong> 16 ton/hr. The pressure <strong>and</strong> temperature <strong>of</strong> the steam are 15 kg/cm 2 <strong>and</strong> 246°C respectively. Bagasse is the primary source <strong>of</strong> which is burnt <strong>in</strong> boiler furnace to generate steam which <strong>in</strong> turn is used to drive steam turb<strong>in</strong>e generators for electricity generation required for motor drives, driv<strong>in</strong>g mill drive turb<strong>in</strong>es <strong>and</strong> for meet<strong>in</strong>g process steam needs. One steam turb<strong>in</strong>e generator is normally operated dur<strong>in</strong>g mill<strong>in</strong>g season to meet the entire electric dem<strong>and</strong>. One st<strong>and</strong>by diesel generator is also available <strong>and</strong> run dur<strong>in</strong>g emergency. Electricity is purchased from Bangladesh Power Development Board (BPDB) as required dur<strong>in</strong>g clean<strong>in</strong>g days <strong>and</strong> dur<strong>in</strong>g <strong>of</strong>f-season. There are also two crusher drive steam turb<strong>in</strong>es, each <strong>of</strong> 580 HP capacity <strong>and</strong> two steam turb<strong>in</strong>e generators, each <strong>of</strong> 1 MW capacity. About 30 tons/hour <strong>of</strong> steam is produced <strong>in</strong> the boiler that has an average efficiency <strong>of</strong> 56 per cent. High-pressure steam is ma<strong>in</strong>ly used for steam turb<strong>in</strong>e generator <strong>and</strong> crusher drive turb<strong>in</strong>es. An automatic pressure reduction valve reduces steam from 15kg/cm 2 pressure to 3 kg/cm 2 that is ma<strong>in</strong>ly used <strong>in</strong> centrifugals for purg<strong>in</strong>g molasses <strong>and</strong> wash<strong>in</strong>g/clean<strong>in</strong>g
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