Jui-Yuan Lee

Design of inter-plant water network with central and decentralized water mains

This paper presents a mathematical model for the inter-plant water integration of an industrial complex that consists of a number of process plants. Opportunities for water reuse/recycle across plants are exploited. In particular, a novel integration scheme is proposed, where central and decentralized water mains are placed to interconnect the water-using units of the individual plants. The principal advantage of using water mains is to improve the overall network practicability. The model formulation is based on a series of superstructures, and the design problem is optimized according to two objectives that include the minimization of fresh water consumption and total annualized cost. An example is solved to illustrate the proposed integration scheme and approach.

Synthesis of water-using network with central reusable storage in batch processes

Abstract The starting and finishing times of water-using operations in batch plants are dependent on the production planning and scheduling. For maximizing the possibility of water reuse/recycle, or for minimizing the freshwater consumption, central storage facilities in a batch water-using system can collect the reusable water from the earlier operations and then supply the remaining water to the later operations. For a predefined production schedule, this paper presents a mathematical formulation for the synthesis of batch water-using networks with central storage tank(s). Superstructures that incorporate all possible flow connections are built to facilitate the problem modeling. The design problem is formulated as a nonlinear program (NLP) if there is no limitation to water reuse/recycle, or a mixed-integer nonlinear program (MINLP) when forbidding water reuse between assigned water-using units and water recycle of certain water-using units is considered. A published literature example and some adaptation examples are provided to demonstrate the good expectation of the proposed, superstructure-based NLP and MINLP formulations. As supported by the results, superstructures with the design scheme can effectively accomplish the objective of solving the design problem for minimum freshwater consumption and offering the optimal network configuration.

Targeting and design for batch regeneration and total networks

Resource conservation for batch processes is gaining good attention in recent years. This is mainly due to the recent trend in chemical engineering that focuses on product engineering, as well as in the rise of various low volume and high value-added products (e.g. pharmaceutical, specialty chemicals, etc.) in the market. In this study, a systematic procedure to perform targeting and design of a batch resource conservation network (RCN) involving material regeneration and waste treatment (also known as a total RCN) is proposed. The procedure is applicable for all fixed-schedule-type batch RCNs with mass storage facilities. Literature examples are used to elucidate the proposed procedure.

Application of a simultaneous approach for process scheduling and water minimisation in batch plants

Abstract Batch processes have received considerable attention from both industry and academia for their flexibility and suitability to produce low volume, high value-added products, also as a result of the recent trend towards product-centred manufacturing globally. A growing area of interest is the synthesis of batch water network. In the present work, the automated targeting model (ATM) is embedded in a scheduling formulation to allow simultaneous targeting and process scheduling and the true minimum flow/cost targets to be located. An industrial case study on polyvinyl chloride (PVC) manufacturing is used to demonstrate the application of the proposed simultaneous approach.

Synthesis of water networks for processes with mixed batch and continuous units

Abstract This paper presents a mathematical model for the synthesis of water networks, where both batch and continuous units are involved. For cases where the number of batch units is greater than that of continuous units, a dividing approach is proposed. By treating continuous operation as a combination of batch operations, the original design problem is simplified and the remaining task is almost to synthesize a batch water network. The model is formulated as a mixed-integer nonlinear program based on a superstructure including all feasible network interconnection. A modified literature example is solved to illustrate the proposed approach.