Framework methodology for increased energy efficiency and renewable feedstock integration in industrial clusters

Energy intensive industries, such as the bulk chemical industry, are facing major challenges and adopting strategies to face these challenges. This paper investigates options for clusters of chemical process plants to decrease their energy and emission footprints. There is a wide range of technologies and process integration opportunities available for achieving these objectives, including (i) decreasing fossil fuel and electricity demand by increasing heat integration within individual processes and across the total cluster site; (ii) replacing fossil feedstocks with renewables and biorefinery integration with the existing cluster; (iii) increasing external utilization of excess process heat wherever possible. This paper presents an overview of the use of process integration methods for development of chemical clusters. Process simulation, pinch analysis, Total Site Analysis (TSA) and exergy concepts are combined in a holistic approach to identify opportunities to improve energy efficiency and integrate renewable feedstocks within such clusters. The methodology is illustrated by application to a chemical cluster in Stenungsund on the West Coast of Sweden consisting of five different companies operating six process plants. The paper emphasizes and quantifies the gains that can be made by adopting a total site approach for targeting energy efficiency measures within the cluster and when investigating integration opportunities for advanced biorefinery concepts compared to restricting the analysis to the individual constituent plants. The holistic approach applied highlights the significant potential improvement to energy and emissions footprints that can be achieved when applying a total site approach

Applying exergy and total site analysis for targeting refrigeration shaft power in industrial clusters

Process cooling below ambient temperature is an energy demanding part of many chemical production processes. Compression refrigeration systems operating at very low temperatures consume a lot of high quality utility such as electricity or high pressure steam to drive the compressor units. In industrial process clusters with several processes operating at low temperatures, it is important to investigate opportunities for exchange of low-temperature energy between processes. This paper demonstrates how total site analysis and exergy analysis can be applied to target for shaft power and related hot utility savings for processes and utility systems operating below ambient temperature. Shaft power targeting by optimizing refrigerant use is conducted. In addition the methodology is extended for shaft power targeting in connection with site-wide heat recovery from cold process streams to generate sub-ambient utility. The methodology is illustrated through application to a case study of a chemical cluster. One chemical plant within the cluster operates two compression refrigeration systems at its steam cracker plant. The results of the case study indicate potential savings of 1.5 MW of shaft power by optimizing the use of refrigerant from the compression refrigeration system and additional 2.5 MW of shaft power by recovering refrigeration from two other sites located outside the cracker plant. In total this corresponds to 15% of the total shaft power consumption of the refrigeration systems. Economic evaluation of the proposed measures indicates a pay-back period of approximately 4 years

Comparing efficient computation methods for massless QCD tree amplitudes: Closed Analytic Formulae versus Berends-Giele Recursion

Recent advances in our understanding of tree-level QCD amplitudes in the massless limit exploiting an effective (maximal) supersymmetry have led to the complete analytic construction of tree-amplitudes with up to four external quark-anti-quark pairs. In this work we compare the numerical efficiency of evaluating these closed analytic formulae to a numerically efficient implementation of the Berends-Giele recursion. We compare calculation times for tree-amplitudes with parton numbers ranging from 4 to 25 with no, one, two and three external quark lines. We find that the exact results are generally faster in the case of MHV and NMHV amplitudes. Starting with the NNMHV amplitudes the Berends-Giele recursion becomes more efficient. In addition to the runtime we also compared the numerical accuracy. The analytic formulae are on average more accurate than the off-shell recursion relations though both are well suited for complicated phenomenological applications. In both cases we observe a reduction in the average accuracy when phase space configurations close to singular regions are evaluated. We believe that the above findings provide valuable information to select the right method for phenomenological applications.Comment: 22 pages, 9 figures, Mathematica package GGT.m and example notebook is included in submissio

Targeting for energy efficiency and improved energy collaboration between different companies using total site analysis (TSA)

Rising fuel prices, increasing costs associated with emissions of green house gases and the threat of global warming make efficient use of energy more and more important. Industrial clusters have the potential to significantly increase energy efficiency by energy collaboration. In this paper Sweden’s largest chemical cluster is analysed using the total site analysis (TSA) method. TSA delivers targets for the amount of utility consumed and generated through excess energy recovery by the different processes. The method enables investigation of opportunities to deliver waste heat from one process to another using a common utility system. The cluster consists of 5 chemical companies producing a variety of products, including polyethylene (PE), polyvinyl chloride (PVC), amines, ethylene, oxygen/nitrogen and plasticisers. The companies already work together by exchanging material streams. In this study the potential for energy collaboration is analysed in order to reach an industrial symbiosis. The overall heating and cooling demands of the site are around 442 MW and 953 MW, respectively. 122 MW of heat is produced in boilers and delivered to the processes. TSA is used to stepwise design a site-wide utility system which improves energy efficiency. It is shown that heat recovery in the cluster can be increased by 129 MW, i.e. the current utility demand could be completely eliminated and further 7 MW excess steam can be made available. The proposed retrofitted utility system involves the introduction of a site-wide hot water circuit, increased recovery of low pressure steam and shifting of heating steam pressure to lower levels in a number heat exchangers when possible. Qualitative evaluation of the suggested measures shows that 60 MW of the savings potential could to be achieved with moderate changes to the process utility system corresponding to 50% of the heat produced from purchased fuel in the boilers of the cluster. Further analysis showed that after implementation of the suggested energy efficiency measures there is still a large excess of heat at temperatures of up to 137 °C

Total Site Analysis (TSA) Stenungsund

This project was carried out in cooperation between the Division of Heat and Power Technology at Chalmers University of Technology, CIT Industriell Energianalys AB, AGA Gas AB, Akzo Nobel Sverige AB, Borealis AB, INEOS Sverige AB and Perstorp Oxo AB. A Total Site Analysis (TSA) was performed in this study which can be used as a basis for future implementations of energy system integration at the chemical cluster in Stenungsund. At first stream data (Tstart, Ttarget, Q) and data on overall utility consumption of all the processes in the cluster was collected. The analysis is based on data collected on process streams heated or cooled with utility exceeding a heat load of 300 kW. Additionally steam from by-product incineration which cannot be utilised in another way is considered as process heat. With this data the current energy system was analysed by determining steam excess and deficit at each steam level and company. After that, the data was represented in curves, the so called total site profiles (TSP) and the total site composite curves (TSC). The curves were used to determine the site pinch (the limiting factor for further integration) and to identify measures to increase heat recovery. The measures found by TSA were assessed qualitatively with respect to feasibility to determine the most attractive measures. Finally the site wide potential for cogeneration and measures for reduction of external cooling demand below ambient temperature was analysed. Main findings are presented in the following: From the stream data collected is can be seen that the total demand of hot and cold utility of the cluster is 442 MW and 953 MW respectively. By-products, which have to be incinerated on-site provide 40 MW of steam. To cover the external heat demand additional 122 MW of heat is supplied by steam/hot oil from boilers or directly by flue gas from added fuels purchased or available on site. The TSP and TSC curves show a site pinch at the 2 bar(g) steam system (132 °C). The site pinch limits the potential for heat integration. To increase energy savings by heat integration it is necessary to change the position of the site pinch. It was shown that theoretically by introducing a site-wide hot water circuit, increased recovery of 2 bar(g) steam and adjustment steam levels in several heat exchangers the pinch point can be moved so that hot utility savings of 122 MW plus excess of 7 MW steam at 85 bar(g) can be realised. Only introducing a hot water circuit can save 51 MW of steam from added fuels, which corresponds to estimated savings of 122 MSEK/year. It is possible to replace more steam by hot water, but the demand for 2 bar(g) steam is limited. Therefore a demand for low pressure steam must be created by adjusting steam levels in order to utilise more waste heat in a hot water circuit. The present delivery of heat to the district heating system is not affected by a site wide hot water circuit. There is potential for increased recovery of 33 MW of 2 bar(g) steam from process heat. This would replace the production of the same amount of steam in the boilers, worth 79 MSEK/year. A qualitative assessment on the implementation of a hot water circuit shows estimated steam savings of 55.2 MW (132 MSEK/year) with moderate changes (83.5 MW including more complex changes, 200 MSEK/year). Technically the introduction of a hot water circuit includes hot water pipes between several plants, as most of the consumers of heat are situated at the cracker site and at Perstorp but the sources are spread out across the cluster. Also piping is necessary to transfer the 2 bar(g) steam replaced by hot water to other plants with steam deficit. The practical potential for increased 2 bar(g) steam recovery is estimated to 4.2 MW (10 MSEK/year) with moderate changes and 26.6 MW including more complex changes (64 MSEK/year). Increased 2 bar(g) recovery implies the construction of steam pipes from Borealis to Perstorp and INEOS, as most of the potential steam sources are located at Borealis but Perstorp and INEOS have a demand for 2 bar(g) steam The theoretical cogeneration potential in the cluster is 19 MWel in addition to the 10 MWel generated today (additional revenue is 40 MSEK/year) assuming that steam demand at all pressure levels remains the same but the steam systems are connected with each other. A practical option to increase cogeneration with the existing equipment is to supply steam below 8.8 bar(g) produced at Borealis to INEOS, Akzo and Perstorp. This would result in additional 8.6 MWel by cogeneration in Borealis turbo-alternator (estimated revenue: 18 MSEK/year). Some process streams below ambient temperature are heated with steam. It has been shown that 6.5 MW steam is used for heating stream well below ambient temperature. This steam can be saved and the cooling energy can be recovered. This decreases the energy usage in the cooling system and also saves heating steam. Savings up to 48 MSEK/year were estimated. It has been shown that by site wide collaboration it is possible to increase heat recovery, cogeneration and utilisation of waste heat. The results from this study are the bases to identify concrete projects which contribute to cost and CO2 emissions savings. The study also shows the advantages of TSA in order to find solutions for process integration by the utility system on a site wide level

Trends in female breast cancer incidence, mortality, and survival in Austria, with focus on age, stage, and birth cohorts (1983-2017)

Breast cancer (BC) is the most commonly diagnosed malignant disease and the leading cause of cancer death in women in Austria. We investigated overall and subgroup-specific female breast cancer rates to provide a comprehensive analysis of trends over several decades. Incidence, mortality, and survival, as well as age-, stage-, and birth cohort-specific incidence were analysed using nationwide cancer registry data on 163,694 cases of female breast cancer in Austria (1983-2017). Annual percentage changes were estimated using joinpoint regression. BC incidence underwent linear increases until 1997 and reversed with statistically non-significant declines until 2017. After initial increases in BC-specific mortality, rates were stable from 1989 through 1995 and started declining thereafter, although statistically non-significantly after 2011. Overall BC-specific survivals, as well as survivals according to the calendar period of diagnosis, increased throughout the observation period. Incidence in younger women (aged 44 and lower) showed linear increases, whereas for women aged 45 and higher mostly stable or decreasing rates were observed. Localised BC incidence increased markedly and started declining only in 2012. Distant disease-BC incidence decreased through the whole observation period and incidence of regionalised BC started declining in 2000. Birth cohort-specific incidence peaked in women born between 1935 and 1949 (ages 45-74). In conclusion, the incidence of BC in younger women is increasing, while overall female BC incidence and mortality are stable with non-significant declines. Further, increases in the incidence of early-stage BC (localised) seem disproportionately high in comparison to more modest decreases in late-stage BC incidence (regionalised and distant disease)

Long-Term Outcomes Following Single-Stage Reamed Intramedullary Exchange Nailing in Apparently Aseptic Femoral Shaft Nonunion with Unsuspected Proof of Bacteria

Background: The aim of this study was to evaluate detection rates and risk factors for unsuspected proof of bacteria, as well as clinical and radiologic outcomes following femoral shaft nonunion without clinical signs of infection treated by a single-stage surgical revision procedure including reamed intramedullary exchange nailing. Methods: A retrospective cohort study was performed in a European level I trauma center between January 2015 and December 2022. Fifty-eight patients were included who underwent reamed intramedullary exchange nailing as a single-step procedure for surgical revision of posttraumatic diaphyseal femoral nonunion without any indications of infection in medical history and without clinical signs of local infection. Clinical details of the patients were analyzed and functional and radiologic long-term outcomes were determined. Results: In all patients, with and without proof of bacteria osseous, healing could be observed. The physical component summary of the SF-12 demonstrated significantly better results at least one year after the final surgical revision in case of a negative bacterial culture during exchange nailing. Conclusions: Clinical long-term outcomes demonstrated a trend towards better results following femoral shaft nonunion revision if there was no evidence for the presence of low-grade infected nonunion. In this case, a single-stage surgical procedure may be recommended