Research On Automatic System Of Coagulant Dilution And Addition In Water Works

Through analyzing the domestic and foreign coagulant dosing systems concerning water treatment plant and the practical situation in China, the automatic coagulant dosing system with the core of gravitational dosing is put forward in this paper, which successfully solved the operating instability of dosing system that has always been a puzzled problem to water plants. This economic and reliable system can be used in large, medium and small water plants, wastewater treatment plants and other places (e.g. chemical plants), having a great potential for application.Water plant coagulant dosing system is generally composed of mix subsystem that accomplishes medical mixture of needed concentration and dosing subsystem that realizes the dosage of mixed chemicals to given points in terms of requirements. By application investigation of mix subsystem in practice, special measure device was produced and substituted the widely used electromagnetic flow meters in order to solve the problem of original coagulant measurement existing in the chemical mixture. This device is simple in structure and apt for automatic control. Using this method to realize automatic mixture of chemicals can decrease numbers of system instruments. Through application investigation of dosing subsystem and utilizing principle of fluid mechanics (Bernoulli equation), quantitative dosing device was produced to measure chemical dosage, so as to settle the problem that metering pumps and electromagnetic flow meters widely used in water plants now have a very high requirement in technique and a very high cost in maintenance. This device is easy to control, simple in maintenance and low in cost; functionally it can substitute for metering pumps and electromagnetic flow meters used in system. The application of automatic mix subsystem and dosing subsystem adopting new techniques makes the investment of chemical dosing system and operating cost decrease greatly. Now, this two measure methods have been patented.In practice, data acquisition, computing of chemical dosage, chemical mixture and chemical dosing can be integrated organically by utilizing modern automation technology, which enables the difficult manual chemical dosing system to become an integrate equipment and makes dosing automatically realized only if the required chemical dosage is input. The automatic chemical dosing system studied here does not get involved with coagulation mechanism and other problems of technics, butaccomplishes the dosing of coagulation dose determinated by technics system at all. Through research of automatic dosing system, established by determining automatic dosage in the methods of transmittance pulsation, streaming potential and mathematical model, it can be concluded that the automatic dosing system brought forward in this paper can fulfill requirements of the technics. Likely, this system can also be applied for dosing of other chemicals in water plants, chemical dosing of wastewater treatment plants and other similar places.This new-style automatic dosing system has achieved good economical and environmental benefits since it is put into practice in No.2 water plant of Chengtu Water Supply Co.