(463f) New Systematic Approach Using Combined Constraints Logic Propagation and Mathematical Programming Techniques for Energy Efficient Synthesis of Eco-Industrial Parks

Industrial symbiosis adaptation on the road to having real Eco-industrial parks (EIP) can serve a significant role in realizing economic, environmental and social benefits to both industrial and non-industrial communities.

Even though, Eco-industrial Parks are often publicized as a mean of reducing environmental damage through reduced waste; the major driving factor for the creation of most eco-industrial parks has been to attain financial gain. Industrial clusters played a significant role in the economic growth of many countries. Industrial ecology concept may promote a new path of local development through the transition from industrial clusters to EIPs (eco-transformation). It is the best exploitation of the geographic proximity of time-dependent and non-dependent plants and the non-industrial community of malls, hospitals, hotels, housing compounds, schools and so on, that make the eco-transformation of industrial complexes financially warranted. Implementing Eco-Industrial Parks’ principles in an existing industrial cluster represents a significant opportunity for its revitalization. IEP could exploit synergies from industrial clusters and non-industrial activities to easily create new production models in which the economic and environmental dimensions are symbiotic.

Previous EIPs key success has been a sequence of independent economically driven actions. Such evolutionary pattern followed by countries like Denmark for instance, may not be easily transferred to other eco-transformation potentials. The authors in this paper present a holistic approach in addressing the problem, using new concept of sharing, method, and retrofit tools.

The literatures show that it is very difficult, with the current state-of-art methods and tools, to manufacture EIPs to work from scratch. First, there should be the basic ingredients in place, namely the desire of firms and communities to actively participate and the correct membership as well as structure of firms. These basic ingredients can then be enhanced and improved upon, with correct support structure. A major factor that can enhance the success of EIP synthesis or an industrial complexes eco-transformation is the presence of a large firm which acts as a magnet for other ones. From mass and energy integration points of views, the key to developing a successful EIP or eco-transformation applications is to determine the best connections among different industrial plants and its surrounding communities. Specifically it is the material and energy flows relationship among the different members in the alliance of plants or firms which permit establishing optimal linkage to form a fruitful inter-dynamic structure. If such structure does not exist a successful EIP would not be realized and the eco-transformation of an industrial complex would not be worth exploring. This paper addresses the energy component of EIP via novel system approach.

The current approach for the eco-transformation or the planning of new EIPs for energy efficiency maximization is the export of waste heat from one plant to a nearby another. In other words, each firm in the eco-industrial park alliance allows the usage of its waste energy to be another adjacent firm. The energy waste of one company is used partially or totally in another adjacent one. It is merely a sort of cooperation through the waste integration to save transportation cost and energy degradation during transit.

The current technical sharing methods are essentially three. The first one is the ad hoc method of sharing in which an obvious waste heat stream from a power plant, for instance, is used in a nearby process. This method is not systematic and not efficient where huge amount of energy efficiency opportunities will be left untouched.

The second method is the total site based pinch technology where the waste heat from all processes can be theoretically considered as a source of heat in other processes. The waste heat sources are converted first to steam, and then passed to processes that are in heat deficit through the steam system infrastructure. To identify the external heating and cooling requirements of a group of individual plants from the central utility system, the temperature/enthalpy data from individual plants are first required to be extracted from the plant after the thermal integration of its hot streams to be cooled and cold streams to be heated using individual plant’ grand composite curve. This curve defines each plant’ thermal heat deficiency and thermal heat surplus after intra-plant heat integration. The collection of grand composite curves of the whole site are then used to graphically add all thermal deficiencies to draw the total site heating demand curve, and add all thermal surpluses to draw the total site cooling demand curves. Such two curves are superimposed on one graph with the existing and/or suggested steam generation levels and steam supplying levels to find the minimum total site combined heating and power (CHP) external energy utilities requirement and naturally best indirect inter-plants thermal integration. In this method, intra-integration is done first, which means only waste heat of one plant is shared with other parks’ members (which is not proactive form of cooperation). In this method, the mismatch in number of steam levels required for EIP users in generation and utilization result in energy loss. This method while in literature addresses in its application both time non-dependent and dependent sites processes, the use of time as an optimization variable for hybrid inter-time-inter-systems energy integration is ignored. It also ignores the integration of the combined cooling and power generation/consumption (CCP) system with the total site. The third method uses mathematical programming but with many assumptions to be able to model the whole city’ industrial and non-industrial processes without having mathematically an intractable problem. It can theoretically speaking find best mass and energy integration linkage among the EIP members and design the optimal energy utility systems. However, up to our knowledge there is no public domain literature for any application of such method in the retrofit and/or planning of energy efficient EIPs.

From the EIP synthesis and/or eco-transformation tools, software, we do not have much. The most famous software that can be partially used is the aspentech company total site commercial software. Other US EPA’ decision support program products/software for Eco-industrial Park planning in general, namely “FaST”; “DIET” and “REaLiTy”, are data base software with linear programming capability. These software are essentially focused on material exchange and the very obvious waste heat exchange; where a waste heat stream in one plant/power station is used in other eco-industrial park’ plants.

The well planning of new EIP or industrial complexes eco-transformation can brings significant value to energy efficiency, it is about more than twenty percent consumption saving. However, the problem is mathematically huge multi-variable multi-dimensional optimization problem in which the eco-industrial park network depends on as small as stream condition and as big as the whole park functionality. Integration among many industrial plants and non-industrial ones, in adjacent geographical locations, can bring in more degrees of freedom to optimize the “waste energy recovery problem” and consequently presents new horizon to the radical energy-based GHG emissions reduction to levels never thought of before.

It is true that we still face many arguments against the eco-transformation applications such as the processes are having different start up and shut down times. Besides the processes can work at partial loads and the processes can have seasonal changes in its conditions. From capital point of view we all know that in eco-transformation cases utility systems, heaters and heat exchangers network, coolers capital will not be reduced. On the processes control side the disturbance in one process can propagate to another one if they are integrated which make the process difficult to control and the distance-time known as velocity lags affect the controllability of processes. Last but not least, the geographical distances among firms will cost us energy in pumping or compression and capital in piping, pumps and compressors beside safety issues due to the travel of a fluid from one area to another as well as the fear of leakage. However, many of the practical reasons hindering the application to date, even though they are valid, most of it can be addressed in a novel cost-effective way.

This paper presents new concept, method and tool for total site energy integration which includes many plants and utilities system to attain new levels of energy saving and GHG emissions reduction. The paper uses hybrid, direct and indirect, method that systematically looks to all options together and find best combinations out of the available solutions package while considering both inter-time-zones-inter-systems energy integration. This paper is a continuation-in-part to previous pinch-based methods for enhancing energy efficiency via systematic inter-processes integration as a preliminary screening tool. However, our new method includes new steps for systematically identifying hybrid direct and indirect inter-systems-inter-time-zones matching solutions through selecting best energy efficient routes; generating technically viable energy efficient eco-industrial parks alternatives, identifying best generation and allocation of energy utilities and synthesizing the utility systems which satisfies the eco-park demands during each time zone as well as rendering its best operating scenario at each specific time-zone. The paper identifies using a simple constraints logic propagation model the best and the second best and so on matching among plants. The new systematic method for membership uses constraints logic propagation (CLP) and the mathematical programming model is used to find best cost-effective detailed solutions. The method and the models are illustrated by two industrial scale case studies. The first one is a typical state-of-art oil refinery and the second one is an integrated multi-generation gasification-based facility.

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