Saving energy costs with your condensing turbine generator

Pulp and paper industry has been using steam turbines to generate power and reduce energy costs for many years. The operation of a condensing turbine in an industrial sewer plant is similar in many respects to the operation of a conventional fossil-fuel-fired utility station. Utility companies focus on converting fuel energy into electricity at the lowest possible cost. Thus they can usually sell power at a price that is lower than the cost of generating condensing power in an industrial plant if this power comes from purchased fuel and the comparison includes the capital costs. In most pulp mills, installing a condensing turbine to reduce energy costs would not be an attractive investment. This paper presents two analyses. The first considers the economics of loading up a turbine condensing section that is normally operating at low flow. This requires no capital investment, and savings depend on the relative costs of purchased fuel and electricity. The second analysis considers utilization of low-grade condenser heat to increase the temperature of process water, thereby reducing purchased energy costs. This requires some capital investment and has practical application in mills where the process water supply is cold during much of the year.