Material recycle/reuse is one of the key strategies in reducing the consumption of fresh resources in the process industries. Over the past decade, several techniques have been developed to reduce the consumption of specific material utilities such as water and hydrogen. To date, none of the published techniques provides a noniterative, systematic, and graphical technique for identifying a target for minimum usage of the fresh resources ahead of detailed design of the recycle/reuse network. In this paper, we present a rigorous graphical targeting approach to minimize the use of fresh resources by using segregation, mixing, and direct recycle/reuse strategies. First, the problem is formulated mathematically to provide a systematic basis for its solution. Then, dynamic programming techniques are employed to derive the mathematical conditions and characteristics of an optimal solution strategy. These conditions and characteristics are transformed into a graphical form that can be readily used to identify rig...

Rigorous graphical targeting for resource conservation via material recycle/reuse networks

Material recycle/reuse is one of the key strategies in reducing the consumption of fresh resources in the process industries. Over the past decade, several techniques have been developed to reduce the consumption of specific material utilities such as water and hydrogen. To date, none of the published techniques provides a noniterative, systematic, and graphical technique for identifying a target for minimum usage of the fresh resources ahead of detailed design of the recycle/reuse network. In this paper, we present a rigorous graphical targeting approach to minimize the use of fresh resources by using segregation, mixing, and direct recycle/reuse strategies. First, the problem is formulated mathematically to provide a systematic basis for its solution. Then, dynamic programming techniques are employed to derive the mathematical conditions and characteristics of an optimal solution strategy. These conditions and characteristics are transformed into a graphical form that can be readily used to identify rigorous targets for minimum usage of fresh resources. The graphical technique is also useful in locating a material recycle/reuse pinch point, which provides insightful information on the use of fresh resources, the discharge of unused materials, and the relationships between process streams (sources) and units (sinks). Several test problems are solved to illustrate the ease, rigor, and applicability of the developed targeting technique.

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PROCESS DESIGN AND CONTROL Rigorous Graphical Targeting for Resource Conservation via Material Recycle/Reuse Networks

https://www.ou.edu/class/che-design/pub-papers/A%20review%20of%20recent%20design%20procedures%20for%20water%20networks%20in%20refineries%20and%20process%20plants(Bagajewicz)-00.pdf

A review of recent design procedures for water networks in refineries and process plants

Water network synthesis has been an active area of research for the past one and a half decades. Many think that the technology reached a mature stage in the late 1990s, especially for the insight-based technique based on pinch analysis. The only review for the field dates back to 2000. However, many new papers published in this century reveal that new research gaps are found and more works were carried out to address the limitations of the “old” techniques. The main objective of this review is to provide a state-of-the-art overview of the insight-based techniques developed in the 21st century, particularly those developed for single impurity network of the fixed flow rate problems. Comparisons were also made between these recent techniques and those developed for the fixed load problems in the past century. Various flow rate targeting techniques developed for water reuse/recycle, regeneration, and wastewater treatment are reviewed in detail, along with the network design techniques that achieve the estab...

/pdf/state-of-the-art-review-of-pinch-analysis-techniques-for-3379g4mv9m.pdf

State-of-the-Art Review of Pinch Analysis Techniques for Water Network Synthesis

A new graphical targeting method for water minimisation

Environmental protection, rising costs for wastewater-treatment, and at many sites a shortage of fresh water are all persuasive motives for reducing raw water consumption and wastewater discharge at a chemical-process plant. Maximizing the re-use of water within the plant can be of great help. Systematic strategies for such maximization can lower freshwater usage and wastewater discharges by 50% or more, while also significantly reducing capital investment in treatment facilities. The typical base case or starting point for such improvements appears in a figure which shows a conventional water network in a process plant. After undergoing initial treatment, the incoming water goes in parallel streams to the various individual process units, as well as to the utility system for steam production and for use in cooling towers. Wastewater streams from the processes, along with blowdown and condensate losses from the utility system, are usually collected together and the combined stream fed to a wastewater treatment facility prior to discharge. There are two basic strategies for reducing water demand in such a plant. One strategy consists of modifying individual process and utility units to reduce their inherent need for water. Examples include replacing water cooling with air cooling, improving controls of boilermore » and cooling-tower blowdowns, and increasing the number of stages in an extraction unit that employs water as its extractant. In the other basic strategy, which is the main focus of this article, the engineer seeks opportunities to use the outlet water from one operation to satisfy the water requirement of another or the same operation. In some cases, the water may require some regeneration prior to re-use. Examples of regeneration include pH adjustment, filtration, membrane separation, sour-water stripping and ion exchange.« less

N. Ramchandani

Papers

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