Cogeneration is a process which simultaneously produces two or more forms of useful energy such as electrical power and steam, electric power and shaft (mechanical) power etc.

Ugar has been a pioneer of cogeneration in the sugar industry in India, Over the years, The Ugar Sugar Works has reached (in 2-3 phases) a capacity of 44 MW of power, of which 15 MW is used for captive consumption and the balance 28 MW is fed to the grid (KPTCL).

Power shortage has made the sugar industry realize that by using high–pressure Boilers and Turbines from the same amount of input fuel, (i.e. Bagasse) they can generate upto 2 to 3 times more power and after meeting the captive requirements, the surplus power can be exported to the grid.

A sugar factory requires both electrical power & process steam for its operation. With the Indian Government announcing various fiscal incentives for the use of non-conventional renewable energy for cogeneration in sugar factories, it has become a viable proposition to adopt high pressure & efficient boilers using bagasse to generate steam & power economically to make available surplus power for export to the grid.

The power & process steam in a sugar factory can be met in following two ways :

Conventional cogeneration method deploying bagasse fired boiler in conjunction with extraction condensing and / or backpressure steam turbine coupled to electrical generator or double extraction condensing turbine coupled to electrical generator.

Integrated gasification Cogeneration / Combined Cycle (IGCC) technology deploying an external combustor (gassifier) to fire bio-mass fuel & feeding the cleaned combustible gases in a modified gas turbine coupled to an electrical generator & producing steam through recovery of waste heat in exhaust gas through Heat Recovery Steam Generator (HRSG) to meet process steam requirement / power generation.

As mentioned above, Ugar is currently generating power and steam by way of its 44 MW plant. We are using high pressure boilers from ThyssenKrupp (2 nos, coal fired boilers of 80 Tones Per Hour capacity and 62 Kg/cm2 pressure with 480°C) and turbines from Siemens and Shin Nippon (Japan).

In the first phase, started in 1998, we were producing 18 MW power with 10 MW export to the Karnataka grid (KPTCL). In the second phase, in the year 1999, we produced 28 MW with 18 MW of exportable power.

Here, the process steam is required at 8 ata, 200 deg C superheat & 2.5 ata, 140 deg C superheat at the turbine outlet. However in this case the variations in process steam demand has to be taken care of by PRDS, designed to handle surplus steam as well as short supply of process steam. The Process steam at 8 ata & 2 ata would be normally met from a extraction cum back pressure and extraction cum-condensing turbine.