Study On An Adjustive Non-backflow Pulp Distributor Based On CFD

Headbox, known as a heart of papermaking machine heart,which worked as the most critical means of a paper machine,played a vital role on the autoleveling of paper sheets.It is generally required that the pulp can be distributed along the wire of the paper machine through the headbox,and the pulp should be uniform,stable,and not produce cross flow,disturbance and large eddy currents.Moreover,pulp distributor is the first device of the headbox,a good distributor can guarantee a good uniform distribution of the pulp flow when it goes into the headbox.According to the disadvantages of existing pulp distributor,a new type of non-backflow adjustable square cone distributor is put forwarded,which with no return end,and equipped with a set of adjusting device on the back wall of the feed pipe.It is used to adjust the back wall shape of feed pulp by these adjusting devices,so that the pressure distribution of pulp in the feed pipe can be partially adjusted.Meanwhile,as a result of non-backflow,this new pulp distributor can reduce the energy consumption and the amount of pump sizing,and reach the goal of energy-saving.There are four aspects contents completed mainly as the following:(1)To determain the calculation method of non-backflow distributor.Based on the different loss of pressure head,calculation method is divided into four,Baines equation calculation method,simplified calculation method,the design method considering the friction head loss,and the design method of bifurcation head loss.Here,we simplify the calculation method and compare them,Baines equation calculation method was finally chosen.(2)The optimization and influence factor analysis of pulp performance of non-backflow distributor with 600 mm width.The simulation is carried out on the initial model of non-backflow distributor,stress nephogram showed that there exists obvious pressure gradien at the end of the main feed pipe.This may attribute to the dead zone or backflow even vortex formed on the bottom of feed pipe according to the stress nephogram.Therefore,the optimization of distributive branch pipe,bottom of main feed pipe,and backwall of main feed pipe were carried out.Finally,the simulation result showed that the pressure distribution of the distributor and the pressure distribution is uniform,the mass flow rate and expected value of the deviation from the pulp distributing branch before the optimization of -3.98%～8.26% for optimized -2.38%～2.99%.It is also found that the certain range over a long period of transition pipe and the pulp along the cloth slurry pipe wall into the help to improve the performance of pulp distribution.(3) Practical research of the new distributor.Firslyt,the entering pulp of distributor with 600mm width changed,as well as the backwall of main feed pipe.The simulation result showed that cloth slurry pressure distribution uniformly,and the maximum of each row of pipe mass flow of the absolute value of error is 1.7857%.Secondly,conpared the with a reflow distributor with 600mm width,the same width of back cloth paste for each row of a branch of the mass flow deviation is -2.23%～5.87%,the deviation is greater than the utility model has the advantages of no reflow pulp distributor.Finally,in order to further prove the practicability of this new type of,the simulation of the width of cloth pulp model 1800mm(prior model for 600mm width),1800mm pulp distributor pipe beam mass flow of the absolute value of the maximum deviation of 3.25%.(4)It is given that the study of 600 mm width of distributor, in two different pulp inlet amount,in two different shapes of feed pipe,and the shape of bakwall of 1800 mm width distributor.Obtained by contrast, both the width of distributor need five adjusting mechanism,and each adjusting mechanism of adjusting amplitude can meet the production requirements within 2 mm.At the same time, this kind of non-backflow distributor with parabola-shape bottom is in the most help to enhance performance of distribution.