J.J. Klemeš

Targeting and design methodology for reduction of fuel, power and CO2 on total sites

Abstract Simultaneous optimisation of production processes and total site utility systems provides a novel methodology that can reduce energy demands and emissions on a total factory site whilst simultaneously avoiding loss of cogeneration efficiency. This paper reports on the results of studies of total sites where the application of the methodology has achieved savings in fuel of up to 20%, along with improvements in global CO2 levels and other emissions levels of at least 50% when compared to those achieved by application to individual operational processes. The novel methodology took into account the specific features of semi-continuous and batch operations and also the opportunities offered by the multi-objective optimisation of the design strategy for the total site. The environmental costs and potential for regulatory action were also incorporated. Software tools were developed to support the total site approach which was subsequently tested and its capabilities validated by successfully solving various case studies from different industrial sectors.

Cost estimation and energy price forecasts for economic evaluation of retrofit projects

Abstract A cost estimate can have a major impact both on project profitability and influences the technical solution. This leads to a commitment of substantial amounts of money and manpower over an extended time. Various methods often provide different results. These differences can be rather significant towards the real cost of a project and selection of the right arrangements. It is therefore important to use a proper estimate that generates enough confidence to choose the right alternative. Another source of uncertainty during the economic analysis of design and retrofit projects is the future energy price value as part of operating costs. This value can significantly affect the project viability and profitability. This paper gives a summary of the most common methods used for cost estimation of heat exchange equipment in the process industry and the sources of energy price projections. It shows the relevance of the choice of the right method and the most reliable source of energy price forecast used when choosing between alternative retrofit projects or when trying to determine the viability of a retrofit project. Ten methods for heat exchanger costing procedure are considered. Oil, natural gas and electricity price projection figures published in reports of nine established analytical centres are discussed. Web sites of institutions and companies are also included.

Heat integration retrofit analysis of a heat exchanger network of a fluid catalytic cracking plant

The impact of a process system on environmental pollution has both a local and global effect. The performance of the heat exchanger network (HEN) in a plant is an important aspect of energy conservation. Pinch technology and its recent extensions offer an effective and practical method for designing the HEN for new and retrofit projects. The fluid catalytic cracking (FCC) is a dominant process in oil refineries and there has been a sustained effort to improve the efficiency and yield of the unit over the years. Nevertheless, benefits and scope for improvement can still be found. The HEN of the FCC process considered here consists of a main column and a gas concentration section. Appropriate data were extracted from the existing network, using flowsheeting simulation. The stream data consists of 23 hot and 11 cold streams and cost and economic data required for the analysis were specified. The incremental area efficiency methodology was used for the targeting stage of the design and the design was carried out using the network pinch method consisting of both a diagnosis and optimisation stage. In the diagnosis stage promising designs were generated using UMIST developed sprint software. The generated design was then optimised to trade-off capital cost and energy savings. The design options were compared and evaluated and the retrofit design suggested. The existing hot utility consumption of the process was 46.055 MW with a ΔTmin of 24°C. The area efficiency of existing design was 0.805. The targeting stage using incremental area efficiency sets the minimum approach temperature at 11.5°C, thereby establishing the scope for potential energy savings. To achieve a practical project, the number of modifications is limited. The selected retrofit design has 8.955 MW saving – 74% of the whole scope. This corresponds to 27% utility cost savings with a payback period of 1.5 years. The modifications include addition of four heat exchanger units and repiping of one existing exchanger.

Water and wastewater minimisation study of a citrus plant

Water is used in most process industries for a wide range of applications. Processes and systems using water today are being subjected to increasingly stringent environmental regulations on effluents and there is growing demand for fresh water. These changes have increased the need for better water management and wastewater minimisation. Water minimisation techniques can effectively reduce overall fresh water demand and the overall effluent generated. Thus, resulting in lower costs of fresh water and effluent treatment costs. Water pinch analysis embedded in wastewater minimisation techniques offers simple methods and beneficial results when applied to water using industries. This paper describes a water and wastewater minimisation study carried out for a citrus plant located in Argentina. Citrus juice processing plants utilise large quantities of fresh water. As part of this process, significant quantities of wastewater are produced when it comes into contact with the water using operations. The objective of this study is primarily based on reducing the overall fresh water consumption and wastewater produced in this plant, utilising water pinch technology.

Process Integration and Intensification: Saving Energy, Water and Resources

Process Integration and Intensification (PII) is one of the most timely topics in chemical and process engineering leading to energy efficient, substantially smaller, cleaner, safer and optimized processes. The book covers optimization fundamentals and industrial applications. It is an authoritative overview meant to help graduate students as well as professionals to effectively apply PII in plant design and operation.

Capital Cost Targeting of Total Site Heat Recovery

Exploiting heat recovery on Total Site level offers additional potential for energy saving through the central utility system. In the original Total Site Methodology (Klemes et al., 1997) a single uniform ΔTmin specification was used. It is unrealistic to expect uniform ΔTmin for heat exchange for all site processes and also between processes and the utility system. The current work deals with the evaluation of the capital cost for the generation and use of site utilities (e.g. steam, hot water, cooling water), which enables the evaluation of the trade-off between heat recovery and capital cost targets for Total Sites, thus allowing to set optimal ΔTmin values for the various processes. The procedure involves the construction of Total Site Profiles and Site Utility Composite Curves and the further identification of the various utility generation and use regions at the profile-utility interfaces. This is followed by the identification of the relevant Enthalpy Intervals in the Balanced Composite Curves. A preliminary result for evaluation of heat recovery rate and capital cost can be obtained.

Synthesis of Networks for the Production and Supply of Renewable Energy from Biomass

This paper presents a step towards an integrated approach when synthesizing self-sufficient food-and-energy regional networks and utilising multi-functional crops, which can then be used for food and energy production, dedicated energy crops and low-value agricultural co-products, and waste. For the purpose of analysis, the given region is divided into several zones, which are smaller administratively/economically/geographically integrated areas within the region (Lam et al., 2010). The synthesis of energy production and consumption networks is performed using the superstructural approach, supported by mathematical programming methods. The synthesized networks are comprised of agricultural, pre-processing, processing, and distribution sectors. Economical and environmental evaluation is performed and discussed from optimisation, by employing a mixed-integer nonlinear programming MINLP process synthesizer MIPSYN (Kravanja, 2010).

Selected Papers from the PRES 2002 Conference

The development of both the national and world economy is closely connected to the exploitation of raw materials, energy saving, and pollution reduction. The topic has received much attention of late and has been widely discussed both in the media and scientific journals. The idea of a specialized conference closely related to environmental issues such as energy savings and pollution reduction relative to man’s activities has therefore emerged on various occasions. Heat transfer and heat exchangers indisputably play very important roles in this field. One such initiative was conceived as part of the traditional CHISA congresses. CHISA has been organized in the center of the European Continent—the cities of Brno and Prague—in 1962 and has focused on chemical, mechanical, power generation, control engineering, and increasingly environmental and sustainable development issues. A new conference on process integration, modelling, and optimization for Energy Saving and Pollution Reduction (PRES) was firstly organized under the CHISA

Recent Advances on Heat Transfer Equipment Design and Optimization—Selected Papers from PRES 2004 Conference

This editorial provides an overview of a special issue dedicated to the 7th conference on Process Integration, Modeling and Optimization for Energy Saving and Pollution Reduction—PRES 2004. Eight papers have been selected and peer-reviewed covering various subjects of heat transfer engineering, focusing on the recent development of various features of heat transfer equipment design and optimization. This is the fourth special issue of Heat Transfer Engineering dedicated to selected contributions from PRES conferences [1, 2, 3].

A review on the impacts of compost on soil nitrogen dynamics

With the depletion of soil quality, the increased use of inorganic fertiliser is required to cope with the increasing food demand. The increasing use of inorganic fertiliser has become a burden to both the economy and environment. The overuse of nitrogen fertiliser can cause the leaching of NO3- to the surrounding water source and the emissions of N2O and NO to the atmosphere. Besides the environmental issues associated with conventional farming, more attention has been drawn to the rapid population growth and urbanisation that has led to the production of abundant municipal solid waste (MSW). To overcome these problems, composting can be an alternative option to both managing MSW and replacing inorganic fertiliser. As a biological process, composting can utilise the organic fraction of MSW as the raw material to produce compost, a stable form of organic matter that can be used as soil amendment or organic fertiliser. Although the utilisation of compost as an organic fertiliser is quite well studied, less research had focused on the nitrogen dynamic after compost application to soil. It is essential to figure out the correlation between compost application and soil nitrogen dynamic in order to prevent further nitrogen loss as a pollutant after compost application. This paper reviews the soil nitrogen cycle and the potential of nitrogen loss prevention with the application of compost. The application of compost is providing some promising effects in term of soil organic carbon and nutrients replenishment and soil microbial population enhancement. The effects of compost to soil are highly dependent on the characteristics of the raw materials for composting. The presence of high nutrient in compost is not always a good thing since it also increases the risk of nutrient loss through leaching or gas emission. The combination between nutrient rich and nutrient poor compost can be an alternative way to prevent nutrient loss. N2O emission from soil is always associated with high nitrogen content and anaerobic condition in soil. The mitigation of N2O emission can be achieved by compost application, and the addition of biochar during composting process can further enhance the effect.