SKIL in Energy Optimisation
Pinch technology is a relatively modern engineering tool developed in the late 1970's and early 1980's. This new approach to evaluating the energy requirements of a site quickly identified ways of improving the overall energy use. The name "pinch technology" was applied because the technique identified the point or points in the energy flow where restrictions applied and hence limited one's ability to re-use low grade energy.
The major difference between this new technology and previous engineering approaches was the formalised methodology involving the rigorous application of thermodynamic principles. Pinch technology was initially adopted by major chemical companies and the petrochemical energy. Beet sugar was quite quick to adopt it because of the industry's energy profile and it is now being adopted by the cane industry too in order to optimise electrical export sales.
Energy Optimisation Curve
Pinch technology is equally applicable to greenfield projects and refurbishments. In either case the objectives are to achieve:
- minimum energy consumption
- optimisation of utilities
- minimum capital expenditure to achieve these
Minimising energy consumption implies minimising cooling water requirements too because all of the energy used ultimately has to be rejected again in some low grade form.
The technology's strengths are its overall approach to process integration (rather than optimising a single station) and its blend of thermodynamics with commercial requirements. It also takes into account the operational requirements of the site and does not reduce flexibility or availability.
THE SUGAR INDUSTRY
The application of pinch technology in the beet sugar industry is reaching maturity and most important sectors of that industry would see it as a norm for plant optimisations and new projects. The cane sugar industry is only just adopting it.
SKIL's normal approach to the application of pinch technology to existing operations is two phased : undertake an energy audit of the site followed by detailed analysis of opportunities identified in the audit once the client decides to proceed.
Phase I: Audit
The audit phase would typically involve about one week of work at the site for a small team, usually 2 or 3 engineers. During the visit, the team will investigate a variety of issues and identify a series of small potential projects to achieve the objectives. Following some necessary desk work, indicative returns will be presented based on preliminary cost estimates.
Phase II: Implementation
Once the Client has reviewed the potential projects and is confident of reasonable returns, the Phase II work will undertake a full pinch analysis in co-operation with the factory staff and establish a programme for the projects with fully justified returns. The involvement of the factory staff is important to the success of the analysis because only they can inject the requirements of operational flexibility and operability.
The results of the Phase II analysis provide the Client with all the information needed to undertake detailed design and to implement the project in whichever way is selected. Because the returns are frequently significant, as discussed below, an informal reporting as the work progresses allows almost instant benefits to be gained from the analysis.
The returns from pinch technology projects are surprisingly substantial when the maturity of the sugar industry and its level of integration is considered. A few examples serve to demonstrate the point :
- $½ million savings, 0.7 years pay-back
- $4 million savings, 0.3 years pay-back
- $½ million savings, 1.3 years pay-back
Such returns indicate that owners should not automatically assume that their sugar factories are already fully optimised.