The Effect of Permeability on Lignite Fly Ash Pneumatic Conveying System Design

Abstract

The aim of this experimental study was to evaluate the effect of permeability on the mode of flow that lignite fly ash will support in a pneumatic conveying pipeline. This research was initiated by recurring problems with the long distance and high capacity low grade lignite ash pneumatic conveying system at the 1200 MWe thermal power plant, such as clogging, unsteady flow mode, significant increase of velocity due to pressure drop and erosive wear of pipeline. Ash samples were taken during pneumatic conveying system clogging for further analysis. The experiment was limited to measuring parameters that provide data to determine minimum fluidizing velocity and permeability. The results showed very heterogeneous materials of group B by Geldart, what caused specific phenomenon during the experimental fluidization tests. Minimum fluidizing velocity for this kind of material is not authoritative for defining pneumatic conveying system, since extremely heterogeneous materials at this air speed will remain stationary or will convey very slow or with stoppage, and that required velocities are from 10 to 15 times higher than minimum fluidizing velocity. According to the results, this ash is the most suitable for dense phase pneumatic conveying.

Impact of particle size distribution of material on pneumatic conveying operation on example of ground phosphate

“…Experiments on determining permeability were carried out according to ASTM D7743-12 in a standard type of experimental fluidization rig shown in Figure 1 [4], [5].…”

“…There are many phosphate resources all over the world, and considering the fact that different types of phosphate rocks widely differ in their characteristics [1], physical properties of fine grained material must be taken into the consideration [4] in pneumatic conveying system design and operation. This paper will make a short review on problems with pneumatic conveying of ground phosphate that occurred in fertilizer production plant.…”

Validation of numerical models for prediction of pressure drop in high capacity long distance lignite fly ash pneumatic conveying

“…Creating optimal operating conditions is a serious issue [6], and difficulties in daily operation are a regular occurrence [4]. Frequent delays in the ash transport may lead to the shutdown of the thermal power plant [4, --------------5, 7,8]. Proper operation of pneumatic conveying system depends entirely on the characteristics of material, even on the single batch of the same material [9].…”