The Research On The Multi Slit Tapered Pulp Distributor

The modern headbox of paper machine usually use cone pulp distributor which is composed of the transitional tube,main pipe,pulp resistance components and the return device.Commonly used pulp resistance components have branch pipe,orifice plate,ladder diffuser.But now commonly used branch or orifice plate does not have online adjustment function,can not adjust the flow of local pulp tributaries.Therefore based on the invention patent of No-reflow adjustable cone main pipe(ZL201410359742.3)and No-reflow adjustable cone pulp distributor(ZL 201610223937.4 I am the second author of this invention patent).the theory of two-phase fluid mechanics,and the flow characteristics of the pulp in the tapered pipe.The software of FLUENT were used to study the effects of the pulp in the multi-slit tapered pipe flow characteristics and structural optimization of the pulp distributor.a new multi-slit cone pulp distributor is proposed,which eliminates the backflow end and is provided with an adjusting device on each of the slit type flow resistance elements,The adjusting device can change the flow of each pulp tributary to realize the local adjustment of the uniformity of the banner width.At the same time because there is no return flow,the new type of pulp distributor can reduce the amount of pulp to meet the requirements of energy saving.The thesis completed the following three research work in detail,and reached the following conclusions:(1)Aiming at backflow,slit-length,structure of the multi-slit type pulp distributor.The results show that under the same conditions,the pulp distributor of multi-slit structure is more uniform than the branch-type structure,and the maximum error is reduced by 0.9%.when the return flow rate is 12.5%,the length of the slit is 185mm,the pressure distribution is uniform inside the cone main pipe,the flow error of the seam is the smallest,the pulping distribution effect is the best.Optimized each spoiler entrance arc radius of 7.5mm,the exit arc radius of 265mm,diffusion tube length of 90mm,the maximum flow rate of each slit error is 1.43%,which can meet the general requirements of pulp effect.(2)The research on the banner adjustment performance of the multi-slit type pulp distributor with no backflow was carried out.The results showed that before the optimization of the back wall of the main pipe,the flow at the small end of the main pipe is reduced sharply,and the flow error of the slit is 58.9%.Optimized flow error reduced to 4.54%.The flow error decreased to 2.26%when a tangent arc with a radius of 11.2 mm was added to the small end of 10 mm.the flow characteristics of the spoiler adjustment is a parabola.Its flow expression is:y=-0.0841x~2+0.0027x+3.75,where x and y represent the angle of the spoiler and the flow of the slit respectively.(3)The practical research on no backflow adjustable multi-slit type pulp distributor was carried out.Under the same conditions,the absolute deviation of the no-reflow distributor is 1.46%,the absolute deviation of the reflow-type distributor was 1.78%.,and can reduce the amount of pulp to meet the requirements of energy saving.Under different amounts of incoming pulp,By adjusting the spoiler rotating mechanism and simulation make the absolute error of the flow rate at the four speeds after adjustment was not more than 1.70%,and the smaller the amount of incoming pulp changes,the slit flow error is smaller.There is no pressure gradient in the main pipe and the exit of each slit of the2700mm width no-reflow adjustable multi-slit pulp distributor after optimization,and its flow deviation is reduced to 4.9%.After three times spoiler rotating adjustments,the absolute deviation of the slit flow was reduced from 4.9%to2.15%.