Development Of Engineering Drawings For Small Or Middle Low-Temperature Multi-Effect Distillation Desalination System

Along with the development of industry, growth of population and aggravation of pollution, scarcity of fresh water resource has been more and more severe. As a means to create fresh water, desalination gets much attention. LT-MED technology, which is a main technology of desalination, has low operating temperature, flexible unit combinations and it can be driven by low level heat.This article’s theme is study of small or middle LT-MED systems. Their working principle and design method have been put forward. Based on mass and energy conservation, a numerical model of LT-MED system driven by hot water is established, which includes evaporator, condenser, pre-heater and flash box. Given the calculating method of water properties, all the system parameters and computing diagram have been designed. The effect of flow resistance and seawater properties are considered.Furthermore, a program which can generate tubes arrangement drawing of small or middle LT-MED equipments has been programmed by Auto-LISP program. The program consists of four layer blocks and every block contains four view branches. The drawing’s size and structure are decided by given parameter, as a result, the program can be widely used in most LT-MED systems. Generated engineering drawings allow designers to operate.As an example, the design of a LT-MED system driven by diesel engine’s waste heat has been raised to make users understand the process of design easily. It shows how to obtain all the parameters and the engineering drawings. Design notes and applications are given.