Identification, cost estimation and economic performance of common heat recovery systems for the chemical cluster in Stenungsund
In previous work, the heat savings potential that can be accomplished by increased heat recovery collaboration between the constituent companies was identified at the chemical cluster in Stenungsund. Based on this work specific measures to realize the potential were determined. All heat exchangers that can be included in a common heat recovery system were identified and other measures necessary in order to construct such a system were described. Detailed systems design, cost estimation, economic evaluation and cost sensitivity analysis was not dealt with in detail. A number of different systems solutions are available In order to identify cost-efficient system configurations it is important to develop a methodology that deals with design, cost estimation, economic evaluation and cost sensitivity analysis. The present study aims the development of such a methodology in order to enable decision makers to identify and compare cost-efficient and site-wide common heat recovery system configurations.
In a first step all the different cost items of the common heat recovery measures are identified. After that a short cut approach for estimating the different costs (HX, piping, pumps etc.) involved is applied. Later a methodological approach to identify the most cost efficient overall systems solutions is introduced. During this a number of promising options is identified, which then are evaluated in more detail according their economic performance.
As a result five promising systems were identified saving between 20.6 MW and 53.6 MW of hot utility. The estimated Pay Back Period (PBP) of the system was between 3.2 and 4.2 years. Further evaluation showed that especially two systems showed superior economic performance. System 20 recovering 20.6 MW of heat at a PBP of 3.2 years has the best Discounted Cash Flow Rate Of Return (DCFROR) of all systems (34.2 %). The retrofit only involves Borealis and Perstorp. Perstorp only serves as a sink for excess LP steam from Borealis, while recovered excess process heat is delivered from Borealis PE to Borealis Cracker. As it only enables for utilizing a minor share of the total heat integration potential it is considered as a first step towards a larger system.
The final step in the development of common heat recovery systems is System 50 recovering 50.8 MW of heat at a PBP of 3.9 years and a DCFROR of 26.6 %. This system shows the highest Net Present Value of all investigated systems and recovers a major share of the heat recovery potential. Three companies, Borealis, Perstorp and INEOS are involved in the retrofit. Borealis PE and Perstorp are mainly delivering excess process heat to Borealis Cracker, while INEOS solely servers as a sink for excess steam from Borealis Cracker. It is possible to extend System 20 towards System 50 if minor preparatory investments are taken.
Sensitivity analysis showed that only in two scenarios where the price of saved fuel decrease or the total investment costs increase by 30 % the PBP of System 50 exceeds 5 years and DCFROR drops below 20 %. The systems identified can be considered robust to fluctuations in investments costs and fuel price.
The methodology applied in this study was shown to enable for identifying cost efficient and economically robust heat recovery systems and even making it possible to describe staged investment paths where the simplest investments are taken first allowing for further systems extension in order to realize the a larger share of the heat recovery potential.
Total Site Analysis