At present, the most widely used automatic control system in water purification plants is a multi-level distributed computer measurement and control management system composed of industrial computers (IPC) + programmable logic controllers (PLC) + automation instruments.
In a modern water purification plant, every production process is always related to the corresponding instrumentation and automatic control technology. The instrument can continuously detect various process parameters, and perform manual or automatic control according to the data of these parameters, thereby coordinating the relationship between supply and demand, between various components of the system, and between various water treatment processes, so that various equipment and facilities can be updated. Full and reasonable use. At the same time, since the value measured by the detection instrument can be continuously compared with the set value, when deviations occur, adjustments are made immediately to ensure the quality of water treatment. According to the parameters detected by the instrument, it can further automatically adjust and control the dosage of the medicine, ensure the reasonable operation of the pump unit, make the management more scientific, and achieve the purpose of economic operation. Because the instrument has the function of continuous detection and over-limit alarm, it is convenient to deal with accidents in time. The instrument is also a prerequisite for computer control. Therefore, in advanced water treatment systems, automated instruments play a very important role.
The instruments used in water supply projects can be roughly divided into two categories: one category is for monitoring the physical parameters of the production process, such as detecting temperature, pressure, liquid level, flow, etc. This type of instrument adopts domestically made meters, and its performance and quality can basically meet the requirements. The other category belongs to the analysis instrument for detecting water quality, such as detecting water turbidity, pH value, dissolved oxygen content, residual chlorine, SCD value, etc. These special instruments developed relatively late in our country, so they usually choose advanced foreign products, which are more economical and reliable from a long-term point of view.
The quality of the detection instrument is directly related to the effect of water supply automation. In the process of engineering design, we make repeated comparisons in terms of instrument performance, quality, price, spare parts, after-sales service, etc. We generally use the method of combining imported instruments with domestic instruments.