Flow Field Analysis And Optimization Of High Concentration D-type Hydraulic Pulper

With the continuous development of economy and technology,the demand for paper products is increasing,especially in the Internet finance to promote the prosperity of the packaging and transportation industry.The waste paper has become the main raw material in the paper industry,due to increased environmental awareness.At present,the low-concentration pulping method is mainly used in the papermaking industry as there are many problems,such as low efficiency,high energy consumption,and serious waste of resources.Therefore,it is a great significance to design hydraulic pulpers of efficient,energy-saving and environmentally friendly.The following research was conducted on the above problems:A high-concentration D-type hydraulic pulper with a spiral rotor was designed,based on the analysis of the advantages and disadvantages of the basic structure of the hydraulic pulpers.The distributions of pressure field,velocity field and solid content in internal flow field of high concentration O-type and D-type hydraulic pulpers were compared and analyzed,through the basic analysis method of solid-liquid two-phase flow in CFD technology.The variation of solid holdup with time in the upper,middle and lower tank structures was compared and analyzed with different rotational speeds and different initial volume fractions.And comparing the two tank structures with different initial volume fractions at the same speed.It is concluded that the time for solid content of D-type structure to reach stability is short time.The pulp distribution in the region was described by using the percentage of solid content in the regional structure.The degree of deviation was analyzed,by the percentage of paper in each zone for the pulper tank and the percentage of paper in the uniform state.The deviation degree is proposed as a criterion for evaluating the homogeneity of pulper feed liquid.In this criterion,the variation of the percentage of paper in the upper,middle and lower three-layer structure of the pulper with time was compared under different speeds and different initial volume fractions.The results show that the solid content distribution of D structure is more uniform.Optimizing the structural parameters by analyzing the factors affecting the uniformity of the D-type hydraulic pulper.Considering the first-order interaction of rotor structure factors,orthogonal test was carried out.The significant level of influence of each factor was C>B×C>A×C>A×B> B>A.Studing the influence of parameters such as ion diameter,initial volume fraction,rotor diameter,rotor height and D plate position of solid particles on the percentage of paper content.It has an effect on the percentage of paper content in the upper,middle and lower three-layer structure.Then analyze the trends under univariate analysis.The effects of the uniformity of the pulper liquid were compared and analyzed in the case of hydraulic pulpers with and without spoiler.The results show that D plate or additional spoiler can promote the uniform distribution of solid particles.Based on the similarity principle,three scale models are produced,which are spiral rotor,O-shaped structure and D-shaped structure.The modal analysis was carried out to study the dynamic characteristics of the pulper,by using the m+p SO Analyzer data acquisition and modal analysis platform.The modal analysis shows that the D-type structure has better stability.On the basis of the proportional model,the fluid test was carried out to obtain the distribution of the homogeneity of feed and liquid in the pulper.