Study And Application Using Gas-Water Impulse Technique To Solve The Problems Of Secondary Pollution Of Lager Diameter Pipe Network

Secondary pollution of pipeline generally exists in the water supply system. Water quality of high-quality water from water treatment factory often reduces evidently after long-distance transport. Secondary pollution of pipeline is difficult to be resolved because of influence of history, economy and management system etc.. Currently, this becomes the bottleneck problem which limits development of water supply enterprise, especially in the north city of our country.Pipe flushing is one of the best methods which maintain and improve water quality and reduce secondary pollution of pipeline. Effect of traditional flushing methods is not effective and water-wasted. Gas-water impulse washing technique is new technique recently and originates from high-pressure water jetting which uses the air compressibility to inject high-pressure gas into pipe in certain frequency under the control of electromagnetic valve and impulse generator, and forms discontinuous water-gas mixed flow inside pipeline. Tangled flow in pipe suddenly speed up to be changed into fast flow and generate strong washing and jetting effect to pipe wall with hard impurity inside pipeline(e.g. sand and rust etc.). Thus, soft scale and hard scale come off pipe wall and are discharged out with water-gas flow from sewage draining exit. This technique can solve problems of secondary pollution of pipe newtork because of its no corrosion, efficiency and low cost.The issue mainly studies the solution of secondary pollution of large diameter(≥DN400) water supplying pipeline. It introduces in detail the cause of its formation and hazard, origin and principle, workflows and character of gas-water impulse technique of secondary pollution in Daqing district. The issue studies pipe diameter of best sewage draining exit, best distance of flushing, matching principle between water pressure and gas pressure, work habit of gas pulse generator, washing operation time, and also flushing velocity and flow, control of water quality, influence of turbidity of pipe network and bacterial amount, influence of residual chlorine of pipe network and pipe corrosion, pipe thickness etc.. Mass valuable trail data are obtained and application law is found out for water-gas flushing technique applied in lager diameter pipe network. Standard specification of water-gas impulse technique is summarized. It fills the gap of technique in this field and find out the solution of secondary pollution of water pipe networks in Daqing district.The issue summarizes the study and application of gas-water impulse technique, operation steps of pipe flushing, evaluation of data collection, and safe operation etc.. The issue provides reference for water supply enterprises of other district using gas-water impulse technique to solve secondary pollution of lager diameter pipe network.As a new application technique, technique specification summarized is not mellow and marinate because principle and data, experience for references are too little, especially flushing technique≥DN800 isn't still obtained and need to study more later.Later we will direct our attention to how to adjust equipment running parameter timely and moderately and improve flushing quality of gas-water impulse, how to reduce flushing time and consumption of clean water, and how to improve pipe flushing technology and lower the production cost.