Heat Recovery System

Product Details:

All sugar mills based on sulphitation process have an in situ sulphur dioxide generation system comprising a sulphur melter and SO2 burner. Digital Utilities have offered a closed circuit melting system comprising in situ steam generation so as to avoid long steam medium pressure steam line from boiler / PRDS station to conserve thermal energy. This, however, needs a nominal electrical energy.

SO2 gas from the burner is available at a temperature of 500 – 600 oC. It is necessarily cooled to juice temperature level before it enters the Sulphitor. This is presently done in an elaborate water / gas heat exchanger (coolers). This results not only in a loss of precious heat energy but also water loss or expenditure on cooling tower. In our system this waste heat is used to generate steam required for melting the sulfur, thus making the SO2 station independent of boiler operation and tailor made to the operations of sulphitation only.

Waste heat recovery system comprises a shell and tube water vapouriser with hot gases in the tubes and water in the shell. The system is also provided with an electrical back up to be used at the time of start up. This makes the SO2 system completely independent both energy wise and operations wise. A periodic making up of water to the boiler is made using the condensate from evaporator system.

At the time of start-up the electrical heaters provide the energy to convert the water in the vaporizer to steam at 6 Kg/cm2 for melting the sulphur in the melter. Once the molten sulphur is burnt in the furnace to produce SO2 gas, the heat of this reaction produces SO2 gas at about 500-6000C, which is led in to the Waste heat recovery system to heat the vaporizer water from 150-1600C to 1800C. This heated water is then flashed into the vaporizer to increase the heat of the water therein, which is then used to melt more sulphur in the melter. As the water temperature in the vaporizer rises above 1600C the heaters shut off, further conserving energy.