WATER CONSERVATION IN THERMAL POWER PLANT CONSIDERING PIPING COST AND PRESSURE DROP

Abstract

Water is an important element for many industrial operations, and is utilized for a wide range of purposes in industries. The rapid growth in population, coupled with industrialization and urbanization, resulted in an increased demand for water, casting adverse effect on environment. The scarcity and high cost of water along with stricter regulations on effluents have become a significant factor. As water supply and treatment costs increase, there is increasing pressure on the chemical process industries to reduce the water consumption. There are different technologies available to save fresh water and reduce waste water generation. Out of these, WaterPinch is one of the most important technologies for wastewater minimization. Basically, it is a methodical accounting procedure based entirely on mass conservation. This technology treats the water utilization process of an industry as an organic whole and considers how to allocate the water quantity and quality to each water using units so that water reuse is maximised within the system and as a result the wastewater generation is minimized. The Water network design problems are tackled by a number of approaches such as hierarchical design graphical approach and Mathematical Programming approach. We treat water system design as a problem of mass transfer i.e. from a contaminant-rich process stream to a contaminant- lean water stream. In present work Water-pinch, based on the Pinch Technology is applied to design water- reuse networks. The present study is related to the use of water resources to maximize water reuse, minimize waste water regeneration and reduce effluent treatment and design of optimal water network at minimum annual cost. The problem is tackled in two steps. During the first step, a feasible target is established by integrating streams and utilities based on the Pinch Technology. In the second step, a network is designed to satisfy the targeted parameters and finally water network is fine-tuned to get an optimal water- reuse network at minimum annual cost. In this dissertation, sincere efforts have been put to demonstrate the potential of Water Pinch Technology by taking up real world problems of industries. Different case studies are discussed v in details. Case study-1 is a single contaminant problem. Initial consumption of fresh water and waste water of 170 t/h is reduced by 47%.In the case-2 Initial fresh water consumption is 3037 t/d. Fresh water consumption is reduced 17.3% by Water Pinch. Case study-3 is identified as a multi contaminant. The initial fresh water consumption after optimization of network is 139.7 t/h. Case study-4 is also multiple contaminant problems which involve eight operations and only water reuse approach is applied. The initial fresh water consumption is 329 t/h and after optimization is 189 t/h.