| Tap water treatment and facilities for agricultural drip irrigation systems require the addition of medicines or fertilizer to pressure pipelines.Pump pressure and differential pressure vacuum suction these two dosing methods were used commonly.The former needs to consume electricity,and it also needs a set of automatic control system to ensure the ratio of dosing.The latter requires a decompression device on the pipeline,which will cause larger head loss and serious back suction,and the suction process is also limited that affecting its large-scale application.Therefore,it is of practical and practical value to develop a pipe applicator that is simple in structure,does not require electric power and no need to reduce pipeline pressure significantly,dosing evenly and with adjustable proportion.Adding medicines to the pipeline is similar to drip-feeding,so how to make the pressure in the liquid medicines more than the pressure in the pipeline is a technical key.Regarding the issue above,theoretical analysis,design and experiments were developed which lead the new pipe application birth.The main achievements were as followed:1?A new type of dosing device that completely different from traditional dosing principle was designed.By placing the flexible medicine bag in a closed pressure tank,both pressure tank and medicine bag were connected to water pipe,a pressure relief valve is set between the two joints which makes the pressure in the closed tank to be slightly larger than the pressure in the pipe at the outlet of the bag.Medicine can be injected into the pressure pipeline like drip-feeding.Due to the completion of the medicine dosing,it is only necessary to overcome the local head loss during the flow process,this working principle does not require a large pressure difference,the range of pipe's head loss is between 0.1 to 0.5m which can generally negligible.2?Through theoretical analysis,it has been found that the new dosing device has the characteristic of equal proportion dosing.Due to the volume of medicament flowing into the pressure tank and medicine out of the bag is equal.The dosing process is a continuous flow which runs in parallel with the incoming water pipeline,flow of two parallel running pipelines is proportional.So no matter how the pressure and flow in the incoming water pipeline changes,dosing flow and flow in pipes are fixed ratios.In other words,the medicine concentration in the pipeline is constant and this ratio can be adjusted as needed.3?Based on this new principle three kinds of prototypes were tried to be manufactured,they were separately type of differential pressure with diaphragm,extending regular,and gradually shrinking through optimizing the structure and working method of dosing device gradually.A test system was developed,salt water and liquid fertilizer as experiment agent tested on the dosing performance of the new device.The result shows that under the same flow(pressure)condition,the sampling port concentration is basically the same at different times.The maximum relative deviation is only 3.07%.When flow or pressure changes,dosing rate is stabilized at 1.7%and the maximum concentration deviation is 1.67%.Dosing uniformity can reach to 97%which belong equal proportion dosing.At the same time,the range of adjustment of dosing ratio was verified and field test was developed.4?The possibility of applying the new dosing device to small water plants in adding PAC or PAM was discussed.A smaller diameter pipe was connected in parallel with the water transfer supervisor.Take loss of pipeline as differential pressure for completing dosing.The energy consumption is zero because that there is no need to add the pressure relief valves on the main water pipes.5?New dosing device does not consume electricity,it only relied on pipeline pressure to complete dosing.Medicine concentration is not affected by changes in pipeline's pressure or flow.It has self-adjusting function and with advantage of simple structure,easy manufacture,easy installation and use. |
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