Energy optimization at a chemical industry enterprise. Case study - Perstorp AB

Abstract: Executive summary Title: Energy optimization at a chemical industry enterprise Case study - Perstorp AB Authors: Sandra Leksell and Anna Parsdotter Supervisors: Patrick Lauenburg, PhD, Dept. of Energy Sciences, Faculty of Engineering, Lund University and Daniel Hansson, Technical Manager, Perstorp Specialty Chemicals AB Background: The industrial sector in Sweden consumed 152.4 TWh energy in 2010, which represented 36% of Sweden's total energy that year. The chemical industry accounted for 11.4 TWh (7.5%). Energy eciency measures and improvements are given priority by enterprises today, due to increasing energy prices and implemented energy policies. To reduce the competitive threat caused by increasing energy prices, Swedish companies have two options; either negotiate a lower energy price from the energy companies or work internally with energy eciency measures. Industries located in colder climates, having a temperature dependent production, are additionally aected by increased energy prices. Perstorp Specialty Chemicals initiated this master's thesis, because they have experienced a variation in steam consumption at their factories. They believed the reasons behind the variety were that production rate aected the energy consumption, that a cold outdoor temperature resulted in energy leakage and that the base load was similar throughout time. Despite this, they have never performed any thorough energy analysis that conrms to what extent these factors aect the energy usage in the factories. Objective: The objective of this master's thesis was to evaluate the energy consumption, mainly steam usage, at the chemical industry Perstorp AB and this was performed by developing statistical models and evaluating the energy management at the enterprise. Methodology: This master's thesis is divided in two parts, and several dierent methods have been employed in both. The rst part is an Energy usage analysis, which began by creating an overview of the production site and factories. The overview was made after visits to the factories and studies of theirs ow charts. Finally the processes were discussed with employees at Perstorp. Relevant and available energy data were then assembled and evaluated. An energy audit, founded on the energy data, for four polyol factories was performed, where large energy consumers were identied. Later, the energy performance of these factories was evaluated. The latter included a study of which variables that aected the steam consumption, and it was based on the statistical model multiple linear regression. 2 The second part, Evaluating Perstorp's energy management, began with a literature study and an interview with a PhD-candidate at Lund Faculty of Engineering. After this, interviews were performed with employees at Perstorp to gain knowledge on how the energy management was handled at the company. After the interviews, an overview was made of the energy management and working methodology. Energy eciency measures within the company and possible improvements regarding their management were suggested. Conclusion: The main conclusion from the Energy usage analysis, was that the statistical method used, multiple linear regression, can only be applied for some systems. The method is straightforward, proving a correlation, in this case between steam usage and other variables. If the system was complex, with re ows, heat recovery, leakage or other factors aecting the steam consumption, the modelling gave a poor result. However, if the system is simpler, e.g. with a product in ow heat exchanged against the steam ow, or heating of component, where the steam consumption correlates to the temperature, the method can be of great use. The models for two out of four factories resulted in a better correlation. One of the factories with poorer result was examined more carefully with diverting result for the components. Some of the steam consumption should be correlated towards the outdoor temperature instead of production rate, when calculating the company's energy budget. Regarding the second part; the energy management at Perstorp is organized, although it can be improved. The impression the authors got after nishing the interviews at Perstorp was that energy is an important issue, though it is not prioritized from the company's board. Furthermore, the Energy Coordinator believes that the level of ambition can increase at the company. Nevertheless, Perstorp has some good examples of well-practiced energy management: weekly discussion regarding energy ratios, a follow up if the ratio is higher than expected and an Energy Coordinator that wants to improve their ambitions. Still, there are some elds within the energy management at Perstorp that can be improved, most importantly creating an Energy group, which can get a comprehensive view concerning energy issues. Additionally, Perstorp can improve the follow-ups after energy projects are implemented, create long-term energy goals and make the sta aware of these and have better training for the sta.