Waste Heat Recovery. Profiting from an Underutilised Resource. Emma Mooney 1, Krum Semkov 1,2, Catherine Adley 1,

Transcription

1 Waste Heat Recovery Profiting from an Underutilised Resource Emma Mooney 1, Krum Semkov 1,2, Catherine Adley 1, 1 University of Limerick, Ireland; 2 Institute of Chemical Engineering, Bulgarian Academy of Sciences, Bulgaria

2 Research Topic General hypothesis: By developing an advanced process integration methodology, to be named GALGEM (General Approach to Low Grade Energy Management), the amount of waste heat recoverable in an economically viable manner from industrial processes will be increased, with resulting improvement in energy efficiency and reduced environmental emissions.

3 Introduction Energy Supply that is reliable, inexpensive, clean, abundant and indigenous is essential to economic stability and development.[1] Ireland [2]:

4 Industrial Energy Use Approximately one third of total global energy demand is used in the industrial sector [3]. Improving industrial energy efficiency is good for the industry and economy as a whole - improved energy security and emission reduction, however while there is significant potential for energy savings, it is underexploited [3]. Industrial organisations are primarily businesses where energy efficiency is a peripheral issue [4]. Energy efficiency is not generally a primary driver in industrial decision making [5]. Two broad approaches i. improve the efficiency of the industrial equipment ii. recover as much of the waste energy as possible and reuse it. In 2008, it was found that the application of best practices and proven technologies, in the industrial sector on a global scale could have saved between 18% and 36% of the then current primary energy use in industry [6].

5 Research Topic Energy Waste Estimated that 57% of all energy inputted to industry is lost or wasted - 43% is actually applied to process work. [4] Practically every industrial process generates waste heat [7] - generally heat is removed through air/gas ventilation systems, liquid cooling, effluent emission or solid wastes. 20% to 50% of industrial energy consumption is ultimately discharged as waste heat [8,9]. Costly for industry and hence the consumer, but also for the environment [10] - clear that it should be minimized through process design and/or recovery technology. Heat recovery recaptures and reuses this waste - reducing overall energy bill and improving profitability [7]. [16]

6 Research Topic Waste Heat Recovery Identification of waste heat in a plant - preliminary step, carry out an investigation into the possible waste heat sources and potential heat sinks. Critical element is not solely the amount of heat, but rather its value in terms of other properties e.g. aggregate state, temperature, pressure, quantity and availability [8]. The mechanism to recover the unused heat depends on the value of the waste heat streams, in terms of heat available and potential for reuse and on the economics involved [11]. Large potential for efficiency improvement through energy recovery techniques [9,12]. In the 1990 s ~ 30% savings could be made through the implementation of relatively simple heat recovery measures [13]. Significant potential for heat recovery through the use of process integration: Pinch analysis, a process integration technique, as ranging from 3% to 50% with a payback of between 0.6 and 4.7 years [14]. Advanced Process Integration [15] techniques has been proven to lead to an increase in energy saving of 10% [14].

7 Relevance of the Research Topic Benefits of reducing lost/waste (energy) heat Increased competitiveness reducing energy use and the resultant reduction in energy cost leading to an increase in overall competitiveness. Reduced environmental emissions reducing waste heat leads to an increase in energy efficiency and thus a decrease in emissions. Compliance with regulation reducing energy use will assist in compliance with EU and international regulation (Kyoto protocol and EU Emissions Trading Scheme). Reducing the impact of security of supply 87% of Ireland s energy is imported (2010 figures) [16].

8 Approach Recovery of energy - significant energy efficiency and reduction opportunities in virtually all industries [12]. Three essential components to waste heat recovery; i. accessible source of waste heat; ii. recovery technology iii. use for the recovered heat [8]. Obstacles to waste heat recovery high costs, good fit, retrofitting etc. Reasonable payback for the industry & perceived risks are negligible. Implement existing technologies and techniques [13] Carry out further research to enable heat recovery from new sources and increase end use options [8]. The biggest opportunity for efficiency in industry is embedded within the entire industrial process and highlight the huge potential for waste energy recovery [4] systematic energy management approach required [3]

9 Approach Proposed to develop a new approach and methodology GALGEM. General tool/methodology to analyse, identify, select and manipulate low grade energy streams in order to maximise energy savings and gain benefit, thus profiting from energy currently rejected as low grade heat. Not process specific - optimise heat energy use in a variety of facilities and processes. Critical parameters of the waste stream such as exergy, enthalpy, entropy, temperature, pressure, state, location, cost. Second Law Analysis techniques targeted

10 Approach Combine Exergy analysis and the more commonly used approaches. Restrict to physical exergy analysis Distinguish between avoidable exergy loss and inevitable exergy loss - reflecting true recovery potential. The overall goal, the minimisation of exergy output, will be achieved through optimisation of the internal heat exchange in the system, without changes to the process technology.

11 Progress First year of research Refining the research area Investigation of the research topic Academic merit v practical industrial application Number of publications: A. Korobeinikov, J. McCarthy, A. Melnik, E. Mooney, J. Rojas, K. Semkov, J. Varghese, T. Zhelev, B. Thorne, Mathematical modelling of internal heat recovery in flash tank heat exchanger cascades, Proc. of the 75th European Study Group with Industry, UL, June 28 - July 3, 2010, pp T. Zhelev, K. Semkov, E. Mooney, T. Majozi, A. Korobeinikov, Industrial Heat Utilisation through Water Management, 8th International Conference on Heat Transfer, Fluid Mechanics ant Thermodynamics, Pointe Aux Piment, Mauritius, 2011, pp T. Zhelev., K. Semkov, E. Mooney, T. Majozi and A. Korobeinikov, Industrial Heat Utilization through Water Management, Heat Transfer Engineering, 34(14), 2013, Accepted. E. Mooney, K. Semkov, C. Adley, Waste heat reduction and recovery, a pathway to achieving 2020 targets Applied Thermal Engineering, 2013, Submitted.

12 Next Steps Methodology development Model investigation Optimisation techniques Case study test case identification Once developed it is envisaged that this method, GALGEM, will be applied to an existing process as a case study.

13 Acknowledgements Supervisors: Krum Semkov, Catherine Adley, Toshko Zhelev Irish Research Council Intel University of Limerick

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