part 1: overview of cogeneration and its status in asia - Fire

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Summary of country study – Bangladesh 139 heaters, evaporators and pans, etc. Turbine exhaust steam is used in processing juice, i.e. mainly heating purposes. Another automatic steam reduction valve reduces 3 kg/cm 2 steam to 1 kg/cm 2 to supply make up steam. Totally 80 per cent of the condensate is recovered and about 20 per cent make up water is needed for the boiler. During plant visit, it was observed that steam used in heating air of 6 forced air supply units of sugar dryer was being operated with an open bypass valve of traps causing live steam discharge to drains. Though all sugar mills have cogeneration facilities, they operate only during the season, i.e. 150 days per year. If they can be operated during off-season by applying Balancing, Modernization, Rehabilitation & Expansion (BMRE) Programme, more power generated can alleviate the power shortage in the country. Most sugar factories have low-pressure (15 bar) boilers. By installing high-pressure boilers, these can produce more power efficiently. The choice of boiler pressure of 64 kg/cm 2 and above appears inevitable for mills intending to sell power to the national grid. Typically, a well-designed 2,500 tons crushed/day plant can sell 10 MW of power to national grid. There are several technical financial and institutional impediments to the use of energy efficient sugar mills, the most important ones being the policy initiatives and shortage of financial resources. In most sugar factories, there is a lack of sound technical management to maintain high-pressure boilers. The existing low-pressure boiler is itself not being maintained satisfactorily in most cases with the result that there are interruptions in crushing sugar cane. In any event, sugar being still a highly regulated industry, the management is occupied with sugar cane farmers, and the financial and administrative problems of producing and selling, and very few have the time to take up the additional responsibility of electricity cogeneration. Cogeneration with improved technology should be seriously considered in sugar factories of Bangladesh as it offers the following advantages: • It causes no pollution as the bagasse does not produce flash, or sulphur compared to coal used in a thermal plant; • It needs no foreign exchange as the machinery needed for cogeneration boilers, turbines, etc., is indigenously available; • It has a low gestation period of two years compared with four to six years of construction period for a coal-based thermal plant; • It has a much lower installation and recurring cost compared with a conventional fossil fired power plant; • It is small in size and is invariably in the rural area, so the transmission and distribution losses are minimal compared with any centralized plant requiring long lines of distribution; • It places no financial and administrative burden on the utility as it is executed and managed by the sugar factory; It improves the financial position of the sugar factory. Cogeneration in paper mill A newsprint paper mill having a steam turbine cogeneration facility is covered here. The mill presently generates 13.1 MW and purchases 2.5 MW from the utility grid to meet all the electrical energy needs of the site, including the residential zones. Furnace oil is used in boilers for steam generation. Steam generated at 42 bar and 400°C in three boilers with a total installed capacity of 161 ton/hour, is mainly used in three backpressure turbines to generate electricity. After partial
Summary of country study – Bangladesh 140 expansion of the steam in turbine a significant amount of steam at 6 bar is used by paper machine and autoclaves. Presently, 13.1 MW is self-generated and a 2.5 MW is bought from the national grid to run the factory and provide residential lighting. The electrical and thermal energy data of the factory for the year 1994 are shown in Figures 3.4 and 3.5. MWh (Thousand) 12 10 8 6 4 2 0 Jan Feb Self Power Generation Purchased power Mar Apr May Jun Jul Month Figure 3.4 Electricity consumption data of the paper mill in 1994 Thermal Energy (GJ) 3500 3000 2500 2000 1500 1000 500 0 Jan Feb Mar Apr May Jun Jul Month Figure 3.5 Thermal energy consumption data of the paper mill in 1994 Cogeneration in fertilizer plant This fertilizer factory is one of the largest in the country, with a capacity to produce over 1.8 million tons of urea per year. Main energy source used in this fertilizer factory is natural gas that is used in boilers as fuel. Most of the electrical energy used in the fertilizer factory is self-generated and there is provision for buying electricity from the national grid. Aug Aug Sep Sep Oct Oct Nov Nov Dec Dec
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PART 1: OVERVIEW OF COGENERATION AN
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4 Part I: Overview of cogeneration
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State of art review of cogeneration
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Policy framework for promoting coge
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Cogeneration in Asia today 49 1.1 I
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Cogeneration in Asia today 51 4,000
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Cogeneration in Asia today 53 1.3 T
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Cogeneration in Asia today 55 1.3.3
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Cogeneration in Asia today 61 1.7 R
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Cogeneration in Asia today 63 Every
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Cogeneration in Asia today 65 Cogen
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68 Part II: Cogeneration experience
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Cogeneration experiences around the
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Cogeneration experiences around the
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