Research And Application Of Small-scale Water Purification Plant Control System

Tap water has been the main source of towner drinking water for a long time. With the development of technology and society, water-processing technology is becoming better and better while people expect more and more about water quality. The wide use of water-purifying new technics and equipments on the one hand improves water-processing ability and on the other puts forward new demand on the whole system's control and coordination. As a result, how to improve the water-purifying technics and increase automatic control level to ensure water supply quality has been a hot spot for the present.Automatic control is the way of ensuring water-purifying plant security, improving water quality, reducing production consumption and increasing economic benefit. The paper proposed an IPC+PLC control system of configuration'KINGVIEW'as host computer monitor system software and Siemens S7-200 PLC as subordinate computer. IPC+PLC control system which is widely used currently in water-purifying plant has many features, such as distributed control and high reliability, and has some merits, such as concentrated control and easy management.The subordinate computer sets four PLC subordinate stations, and each station controls the pumps, motors and electric valves and at once connects to central control room host computer for concentrated control and management. Directed towards the influence of water quality and flow rate on the adding drug quantity in adding chlorine and drug, fully made use of PLC resource PID control arithmetic was put forward which saves labor force and materials and at the same time implements proper addition and ensures water quality. Based on the background of one water-purifying plant second stage project in Yangquan, this paper summarized the problems in the first stage project and raised a scheme about improving water-purifying technics and control. In technics, chlorine dioxide substituting for the tradition chlorine which prevents organic substance from combining with chlorine(the"three cause"combo is harmful to human), and folded-plate flocculating tank is substitute for the spacer flocculating tank in first stage project and the stream between folded-plate is good to flocculation so as to improve flocculation efficiency.PPI protocol of Siemens exclusiveness is used to transfer signals and data between host computer and subordinate computer. The host computer real-timely receiving various data from PLC constructs information database of the whole factory production process by human computer interface (KINGVIEW). The system mainly completes data, graph and state display, timing and real-time production table print, and timely, overall and accurately gets the local subordinate control stations'running conditions so as to timely regulates equipments to make sure the whole water purifying work can run properly.