Research Of An Artificial Seawater Preparation Device

Artificial seawater has been widely used in aquariums and plants ofseafood farmers rearing marine life, but also largely used in the researchof marine environment and its electric field characteristics in specificmaritime space. Based on a practical research project with background ofcorporate sponsorships, this paper aims at research and design of anautomatic device making artificial seawater in order to give someresearch institution certain technical support for researching electric fieldcharacteristics in specific maritime space. It has the technical demands ofmaking300cubic meters of qualified artificial seawater in specified timeand maintaining its good quality for long period of time. In considerationof the main influence factor of electric field in marine environment beingelectric conductivity of seawater which depends on the temperature andsalinity of seawater in return, the major task of this paper is to design aautomatic preparation device to make artificial seawater by means ofaccurate control of its salinity and measure of its conductivity, in order toprovide technical assistance in simulation of sea environment withspecified electrical field characteristics.This paper has analyzed the structure and composition of artificialseawater preparation process and put forward the overall design idea ofautomatically controlling the process of making artificial seawater，which is based on PLC(programmable logic controller) technique incombination of variable frequency speed control and HMI(human-machine interface) to realize the integrated control of artificialseawater preparation device. The main work contents are function designof the preparation device, comparison and selection of electromechanicalequipment for assemble of the preparation device, schematic diagramdesign of electrical control for the electromechanical equipment, programdesign of PLC for realization of controlling artificial seawater preparationprocess, HMI programming design and reliability design. In this paper the technical demands have been met by firstlypreparing strong brine with high salinity in proportional to the specifiedartificial seawater’s salinity and then mixing the strong brine with freshwater by means of variable frequency speed control of the brine pumpflow in proportion to the fresh water flow to reach the goal of accuratecontrol of the artificial seawater’s salinity. In consideration of variousfunctions needed to be realized for the preparation device and complexityof technical process flow, the device has been decomposed into7subsystems functionally and the process flow has been decomposed into5primary operating modes and4auxiliary operating modes and1malfunction diagnosis mode, which are all controlled and realized byPLC and HMI programming control. In addition, this paper has carriedout hardware and software design for reliability, and enhanced the wholelevel of intelligentization and automation for the control system by meansof HMI functions, PLC module programming and malfunction diagnosistechnology, which ensure the preparation device run in order and givesome research institution strong technical support for researching electricfield characteristics in specific maritime space.