Research And Application Of Multiphase Cleaning Technology In Water Supply Pipelines

The water supply system is an essential and vital infrastructure for daily andindustrial use to maintain normal production and living life in modern society. Thewater supply network is an important part of the water supply system, which isclosely linked to water transfer main pipes, secondary pump stations and adjustingconstructions. With the increasing requirements on water quality in our society, thesecondary pollution of the water quality within the water supply network hasbecome an issue that cannot be ignored. Even though the product water quality ofwater plants is strictly complied with the national drinking water standard, the riskof water contamination may still occur at the users’ place if the problem ofsecondary pollution in pipe network has not been solved properly. The main reasonfor the deterioration of water quality in the pipe network can be attributed to the“growth-ring” which is attached to the pipe inner wall. What’s more,“growth-ring”could also reduce the cross section area, resulting in lowering the transfer capacityof water supply pipe networkIn order to minimize the hazards of the “growth-ring” and to improve the waterenvironment in pipe network as well as enhancing the effective water supply output,pipeline cleaning technology is recognized as a preferred method in removing theimpurities in water pipes rapidly. This paper mainly focuses on the multiphasecleaning method which is based on the water-gas pulse pipe cleaning technology.This multiphase cleaning method has many advantages such as environmentalfriendly and high-efficiency etc. In the trial experiment period, we first discussedthe different combinations of pulse frequency, air inlet nozzle shape and the locationof air inlet on the effectiveness of two-phase pipe cleaning by designing andbuilding the test platform. In addition, ceramsite particles were also added into theexperiment pipes turning the flushing process into air-water-solid three-phase flowpattern. It is found that due to the solid particles, the liquid static pressure ispartially converted into the kinetic energy of ceramsite when the particles passingby a certain point with water and gas, which contributes to increasing the effect offriction and shear stress between three-phase flow and the inner wall of the pipes.A numerical simulation research was carried out on the basis of two-phase flowflushing experiment. After simplifying experiment pipes, a physical grid model wasestablished. By using the unsteady solver, an experimental two-phase flow casewithin one flush cycle was simulated to verify the agreement between experimentaldata and simulated results. A better and more intuitive variation trend of water and gas flow performance in water pipe is obtained from the simulated clouds ofdifferent parameters and the curve of shear stress at monitoring spots changing intime.Through applying water-gas pulse pipe flushing technology to real project, thedata of water turbidity and residual chlorine at the end of pipeline was recorded.From the project, it is considered that this technology could effectively clean up thepipes in the water supply pipe network. Water-gas two-phase pulse cleaningtechnology could fix the problem using smaller diameter tube to flush greater one aswell as meeting the requirements of flushing water rate and amount. In sum thisflushing method provides water works a more economical and environmentalfriendly way to solve the secondary pollution in distribution system and ensure theefficiency and amount of water supply.