The purpose of this thesis is to provide Proserpine Sugar Mill with a comprehensive technical and economic feasibility study for the design and installation of a low pressure (LP) steam turbine generator set.
In brief, the concept of the thesis is to utilise excess LP steam currently vented to atmosphere to drive a LP steam condensing turbine coupled to a generator. The main advantages of this process include the increased electricity generation from the LP steam turbine and increased high pressure (HP) power turbine electricity generation. The capture of condensate by the LP turbine reduces the make up water requirements, while Renewable Energy Certificates could be claimed under the Federal Government’s MRET scheme by generating additional electricity from a renewable energy source (bagasse). Due to the operation of the boilers and HP turbines at a higher, more consistent load, the longevity of these components is improved by reducing cycling effects. This increased operating capacity also serves for bagasse disposal, as a greater quantity of fuel is required to burn.
A technical feasibility study was conducted with budgetary quotations sourced from reputable turbine suppliers, a Thermoflex model representation and hand calculations, providing the basis of the analysis. Siemens provided a scope of work and budgetary costing for a 2,100 kW low pressure condensing turbine as 5,680,000 AUD. The hand calculations and Thermoflex model output confirmed the estimated power output to be in the vicinity of 2,100 kW. The technical feasibility was thus proven to be viable.
The economic feasibility involved a capital cost estimate, operational and maintenance cost estimate and financial model. The total capital cost of the project including a 20% contingency is estimated as 8,407,420 AUD. For the 25-year lifecycle of the project the operational and maintenance cost is estimated to be $86,724/ year including 20% contingency. The project was proven not financial viable with the outcomes of the financial model showing that the project will not project will not return a profit over its 25 year lifecycle. Several financial advantages were not included in the analysis due to complicated quantifying methods. It is established that these advantages could improve the economic feasible project.
Overall, it is recommended that the original concept be pursued with the addition of the unquantified financial advantages. If this proves financially unfeasible it is recommended that an alternative concept be considered. The alternative concepts involve a larger flow rate of steam through the turbine, in turn generating more electricity for sale. Initial investigation of these concepts show a high possibility for generating a profit, although specific details have not been determined.