Design And Experimental Study Of Combined Laminated Filter

As a common filter in irrigation equipment,the study of its performance and characteristics is of great significance to irrigation equipment and drip irrigation system.Taking the laminated filter as the research object,this paper studies the hydraulic performance of the laminated filter,the influence of different fertilizer types on the blockage of the filter,and the practical application of the combined laminated filter in irrigation machinery.(1)Carry out two working conditions of clean water and sandy water with the same flow,Mesh number of single laminated filter(three mesh gradients of 150,120 and 80 mesh)and combined mesh(150,120 and 80 mesh combination)test on head loss and filtration performance of laminated filter under two test modes.The hydraulic performance of two types of filters and the relationship between the number of laminated filter mesh,head loss and filtration effect are analyzed.According to the test results of comprehensive performance such as head loss,filtration strength,sand removal rate and filtration uniformity,the combined laminated filter can be known The performance of sheet filter is better than the other three filters(150 mesh,120 mesh and 80 mesh laminated filter).That is,the local head loss is: hj150 mesh > hj120 mesh > HJ combination > hj80 mesh.The filtration strength of the combined laminated filter is 200% and 400% higher than that of120 mesh and 80 mesh,respectively.The highest sand removal rate of the combined laminated filter is 20.3%,and the filtration uniformity of the combined laminated filter is63.1%,36% and 2.9% higher than that of 80 mesh,120 mesh and 150 mesh respectively.(2)Carry out the fertilizer passing test of the combined laminated filter to explore the impact of different fertilizer types on the combined laminated filter.In the water fertilization test,nitrogen and potassium fertilizer operate normally under the combined laminated filter without serious blockage of the filter;However,when applying P fertilizer(calcium superphosphate),because the fertilizer solution is alkaline,it is easy to cause precipitation and blockage.Acidic P fertilizer such as diammonium phosphate(main component 46%)should be used to improve the blockage of the filter.In the process of applying fertilizer by drip irrigation,the concentration of fertilizer solution before and after the filter changes during the application of nitrogen and potassium fertilizer with water,indicating that filtration has a certain impact on the change of fertilizer concentration.The change value is within 0.4%-1.2%.When adding P fertilizer,the concentration of fertilizer solution changes at about 1.2% at first.With the progress of drip irrigation and fertilization,the combined laminated filter is gradually blocked,The change of fertilizer concentration increased to 8.2%.It shows that the blockage of the filter has an impact on the output fertilizer concentration of drip irrigation.The more serious the blockage is,the greater the reduction of fertilizer concentration is.(3)In the fertilizer experiment of combined laminated filter,by analyzing the blocking substances in the filter element,it is found that the blocking substances attached to the filter element contain P fertilizer particles intercepted by the filter element and silicate components in the soil;That is,when the irrigation water quality of the drip irrigation system is poor and the water quality is hard,it is easy to form chemical precipitation and lead to blockage.The filter can filter out some physical blocking substances of particles such as chemical fertilizer and mud sand,and can also intercept some chemical blocking substances.The filter must be cleaned when it runs for 30-50 min,otherwise serious chemical blocking will occur in the filter.(4)In order to solve the problem that P fertilizer(calcium superphosphate)is easy to block the combined laminated filter during fertilization,diammonium phosphate dissolved in water and acidic should be used as fertilizer.In the fertilization test of diammonium phosphate,when the concentration of fertilizer solution is less than 0.09%,the head loss of the combined laminated filter changes little with time,and the head loss is always less than4 m during operation,When the concentration of fertilizer solution is ≥ 0.12%,the head loss increases slowly in the first 20 minutes.When the test time exceeds 20 minutes,the head loss increases gradually with the increase of time.When using diammonium phosphate for drip irrigation fertilization,the appropriate fertilizer concentration is less than 0.09%.In this case,it can ensure that the filter can maintain a long working time,give full play to its filtering effect,and make the drip irrigation work normally.(5)Through the comparative test of combined laminated filter and ordinary laminated filter in intelligent irrigation machine,the repeated test of combined laminated filter in intelligent irrigation machine,and the application test of combined laminated filter in water and fertilizer integration of intelligent irrigation machine.The comparative test results show that the filtration intensity of the automatic backwashing combined laminated filter in the intelligent irrigation machine is 14.3% higher than that of the 120 mesh automatic backwashing laminated filter,and the backwashing efficiency of the combined laminated filter and the 120 mesh laminated filter is basically the same.And carry out multiple filtration effect comparison tests,The test group collected water The impurity content of(2L)is 10.13-11.44% less than that of the control group,and the impurity content is10.13-11.76% lower.The combined laminated filter has good practical application effect in intelligent irrigation machine and high filtration strength.The application repeated test results show that the combined laminated filter has no filter damage,deformation and water leakage under the rated pressure and 2.5 times the rated pressure,and the damage degree of filter element is within the rated pressure Force and 2.5 times of rated pressure are less than 10%;Moreover,the combined laminated filter works continuously for 60 min under the rated working pressure and backwashes for three times.The operation of the filter is normal.The application test of combined laminated filter in the integration of water and fertilizer of intelligent irrigator shows that when the integration of water and fertilizer is implemented by intelligent irrigator and plunger pump fertilization equipment,the variation coefficient of fertilization flow is 2%-5%,and the variation coefficient of fertilization uniformity is 1-5%.To sum up,the combined laminated filter runs well in the intelligent irrigation machine and can be used in the field.