Changing the Air Parameters in the Cotton Pneumatic Transport Pipe

This scientific article examines the issue of changes in the density and speed of the airflow in the pipeline pneumatic conveying equipment used in ginneries, analyzes the causes of changes in the density and speed of air.

Investigation of Changes in Flow Parameters along the Transport Line in Installations for Pneumatic Transport of Cotton

The article presents the results of a study of changes in the parameters of the flow, velocity and pressure of air along the cotton transportation line in pneumatic transport installations and their dependence on the parameters of the pipeline. The purpose of the research is to theoretically substantiate the choice of the pipeline diameter depending on the properties of the material (cotton), the required processing capacity and pipeline throughput. In the research, an analytical method was used to study changes in the pressure of the air flow along the transportation line at different pipeline diameters. It is established that, according to the existing calculation method, the flow pressure along the transportation line is reduced to zero. At the same time, various scientists have proposed various analytical and empirical dependencies, which, in turn, give different ideas about the resistance of the inner surface of the pipes to the movement of air and material flow and do not describe the real situation, especially when transporting material from a long distance. This requires in-depth theoretical and applied research to establish real patterns of changes in flow parameters along the material (cotton) transportation line.

An experimental investigation into modeling solids friction for fluidized dense-phase pneumatic transport of powders

Results are presented of an ongoing investigation into modeling friction in fiuidized dense-phase pneumatic transport of bulk solids. Many popular modeling methods of the solids friction use the dimen- sionless solids loading ratio and Froude number. When evaluated under proper scale-up conditions of pipe diameter and length, many of these models have resulted in significant inaccuracy. A technique for modeling solids friction has been developed using a new combination of dimensionless numbers, volu- metric loading ratio and the ratio of particle free settling velocity to superficial conveying air velocity, to replace the solids loading ratio and Froude number. The models developed using the new formalism were evaluated for accuracy and stability under significant scale-up conditions for four different prod- ucts conveyed through four different test rigs （subject to diameter and length scale-up conditions）. The new model considerably improves predictions compared with those obtained using the existing model, especially in the dense-phase region. Whereas the latter yields absolute average relative errors varying between 10% and 86%, the former yielded results with errors from 4% to 20% for a wide range of scale-up conditions. This represents a more reliable and narrower range of prediction that is suitable for industrial scale-up requirements.

Optimal design of heat exchanger header for coal gasification in supercritical water through CFD simulations

Heat exchangers play an important role in supercritical water coal gasification systems for heating feed and cooling products. However, serious deposition and plugging problems always exist in heat exchangers. CFD modeling was used to simulate the transport characteristics of solid particles in supercdtical water through the shell and tube of heat exchangers to alleviate the problems. In this paper, we discuss seven types of exchangers CA, B, C D, E, F and G）, which vary in inlet nozzle configuration, header height, inlet pipe diameter and tube pass distribution. In the modeling, the possibility of deposition in the header was evaluated by accumulated mass of particles; we used the velocity contour of supercritical water （SCW） to evaluate the uniformity of the velocity dis- tribution among the tube passes. Simulation results indicated that the optimum heat exchanger had structure F, which had a rectangular configuration of tube pass distractions, a bottom inlet, a 200-mm header height and a 10-ram inlet pipe diameter.

Methods for Reducing Seed Damage in the Technological Process of Cotton Processing

The article describes the transfer of cotton to the next technological process while preserving its natural properties during the initial processing process. The analysis of methods of reducing impact forces when removing displaced stones with cotton is analyzed. For this, it is based on the primary processing of cotton.

Optimization and experiment of key components in pneumatic peanut pod conveyor

Research interest in pneumatic conveying technologies in processes such as peanut harvesting and shelling has grown rapidly in recent years.However,the use of pneumatic conveyors in this application suffers from high pod damage rates and duct obstruction.To address these issues,we analyzed the critical speed of pneumatic transport for conveying the peanut pods and measured the angle of friction and coefficient of restitution of peanut pods on a variety of material surfaces.Based on the results of these tests,optimizations and improvements were made to the separator bowl,air supply duct,and conveying duct.A pneumatic conveying experiment was then performed using peanut pods.In the factorial experiment,it was found that increases in fan speed increase the pod damage rate and transport efficiency,while increases in the thickness of the cushioning/anti-obstruction layer decrease the rate of pod damage and transport efficiency.Pod damage rates were significantly affected by fan speed,the thickness of the cushioning/obstruction prevention layer,and interaction between these factors,while transport efficiency was only significantly affected by fan speed.It is proved by the machine verification test,the optimal parameters for the pneumatic transport of Baisha peanut pods with a moisture content of 7.24%was a fan speed of 2700 r/min and a cushioning/anti-obstruction layer thickness of 6 mm.A pod damage rate of 5.19%and transport efficiency of 92.03%were achieved using these parameters,which are sufficient for meeting the requirements of industrial applications.