David B Hastie

The profile of conveyor trajectories

Seven belt conveyor trajectory methods, C.E.M.A., M.H.E.A., Booth, Golka, Korzen, Goodyear, and Dunlop, are presented with their differences explained. Each method uses equations to determine the X and Y coordinates of the trajectory profile. Some methods also use graphical approaches, which allow a quicker determination of the trajectory. Methods such as C.E.M.A., Goodyear, and Dunlop use very few particle properties, while the Korzen method uses many. The parameters used in each method have been investigated to evaluate their impact on the predicted conveyor trajectory. The parameters that showed the most influence are adhesive stress, coefficients of static and kinetic friction, particle shape and size, and divergent coefficients.

The prediction of conveyor trajectories

Seven belt conveyor trajectory methods, C.E.M.A., M.H.E.A., Booth, Golka, Korzen, Goodyear, and Dunlop, are presented with their differences explained. Each method uses equations to determine the X and Y coordinates of the trajectory profile. Some methods also use graphical approaches, which allow a quicker determination of the trajectory. Methods such as C.E.M.A., Goodyear, and Dunlop use very few particle properties, while the Korzen method uses many. The parameters used in each method have been investigated to evaluate their impact on the predicted conveyor trajectory. The parameters that showed the most influence are adhesive stress, coefficients of static and kinetic friction, particle shape and size, and divergent coefficients.

The investigation of particle flow mechanisms of bulk materials in dustiness testers

ABSTRACT The generation of dust occurs in many bulk materials handling applications, including during free-fall, material impact on conveyor transfers, or impact with other materials. Dust has potentially serious consequences to the surrounding environment as well as workers and nearby communities. Companies need to identify and quantify the dust being generated so they can find ways to reduce or eliminate this dust generation. Dustiness testers are one method which can be used to quantify dust generation. This paper investigates the experimental material flow and the subsequent discrete element method (DEM) simulation in the rotating drums of two dustiness testers: the European Standard dustiness tester and the Australian Standard dustiness tester. Preliminary comparisons of the rotating drum designs were undertaken using particle/bulk parameters of polyethylene pellets, a granular “non-dusty” material to investigate the flow behavior, to provide a reference base to compare equivalent simulations and subsequent analysis. A calibrated DEM material model for polyethylene pellets was generated via experimental comparison. Investigations of the rotational speed, volume, and initial loading location of product sample have been performed. The motion of particles in the simulated rotating drums has been compared to visual observation from experimental testing.

Nonintrusive Monitoring of Slug Sequence and Flow Stability in Dense-Phase Pneumatic Conveying

This article presents three sensing methods developed for the nonintrusive monitoring of important flow parameters in dense-phase pneumatic conveying. With the optical measurement system, images of the flow are acquired and an image analysis is used to determine the sequence, length, and velocity of slugs for given materials and operating conditions. The conveying parameters of interest are also monitored with a capacitive sensor by means of exploiting electrical properties of the flowing media. The charge-based measurement system uses a field meter to determine the electric field strength caused by charged particles and provides information about the sequence and regularity of the moving slugs. The noninvasive principle of all three methods avoids concerns about particle contact effects (e.g., wear of the measurement equipment or interference with the flow). All three prototype sensors have been tested under slug flow conditions. A comparison of the three sensing methods against key requirements in pneumatic conveying reveals that capacitive sensing seems to be best suited for reliable flow determination in slug flow.

An experimental investigation into the feed rate capacity of rotary valve and blow tank feeders

Industry widely uses rotary valves and blow tanks for the pneumatic conveying of products, each having their pros and cons depending on the specific application. This article shows the differing results obtained when low-velocity conveying a product through a common pipeline using both a drop-through rotary valve and a bottom-discharge blow tank feeder. A number of issues arise in the rotary valve system, the main one being rotary valve air leakage. A blow tank system, on the other hand, does not leak, as it is an enclosed system. The experimental results show dramatic differences in product throughput. Further exploration leads to a novel modification being made to the rotary valve system in an attempt to increase its capacity. The result of this modification shows a slight increase in output tonnage, but still significantly less than that obtained from the blow tank.

Segregation During Gravity Filling of Storage Bins

Binary mixtures of particles have been prepared in varying proportions and charged into a rectangular two-dimensional perspex bin and hopper. To record the degree of segregation, various methods of mechanical sampling have been investigated and found unsuitable. A new non-intrusive sampling method, which incorporates a personal computer, a video camera and special software to capture and process the relevant images, had to be developed to record the extent of segregation. This technique has been found accurate, convenient and cost effective.

Influences on the Prediction of Conveyor Trajectory Profiles

Seven belt conveyor trajectory methods, C.E.M.A., M.H.E.A., Booth, Golka, Korzen, Goodyear, and Dunlop, are presented with their differences explained. Each method uses equations to determine the X and Y coordinates of the trajectory profile. Some methods also use graphical approaches, which allow a quicker determination of the trajectory. Methods such as C.E.M.A., Goodyear, and Dunlop use very few particle properties, while the Korzen method uses many. The parameters used in each method have been investigated to evaluate their impact on the predicted conveyor trajectory. The parameters that showed the most influence are adhesive stress, coefficients of static and kinetic friction, particle shape and size, and divergent coefficients.

Minimum Transport for Dense-Phase Conveying of Granules

The minimum transport or capacity limitation boundary for low-velocity slug-flow pneumatic conveying affects the design and operation of conveying systems. Unfortunately, the relevant mechanisms involved with this boundary still lack full understanding and assessment. Investigations have been carried out to model the capacity limitation for the low-velocity slug-flow pneumatic conveying of poly granules through horizontal pipes. Pipeline diameter, air mass flow rate, and operating pressure have been found to affect the maximum slugging capacity of this material. A semiempirical equation has been established to predict the maximum solids mass flow rate for a given air mass flow rate and conveying pipeline. Good agreement has been achieved between the model predictions and the experimental results over a wide range of airflows and pressures.

Transportation Boundaries for Horizontal Slug-Flow Pneumatic Conveying

In this chapter, an experimental program is instigated to investigate the boundaries in horizontal low velocity slug-flow pneumatic conveying. A straight horizontal pipeline of length 21 m is set up for actual conveying trials and a simple rig is designed and built specifically to simulate the transportation boundary conditions. The results obtained from the simulation rig are used directly to locate the boundaries in the test pipeline. Good agreement is achieved between the predicted and experimental locations of boundaries. Pneumatic conveying of bulk solid materials through pipelines has been in use for over one hundred years. There are two distinctly different flow modes in pneumatic conveying, dilutephase and dense-phase. Dilute-phase is used widely in industry because of its simplicity in design and operation. However, high air velocities (e.g. 20 to 40 m s -1 ) have to be used in suspension flow, often resulting in problems such as high power consumption, product degradation, and pipeline wear. Low-velocity slug-flow pneumatic conveying, or dense phase, has received considerable attention over the past decade from both researchers and commercial suppliers of equipment to overcome these problems. In slug-flow pneumatic conveying, the bulk solids are transported in slugs and there is no relative motion between the particles within the moving slug. Therefore, power consumption, product degradation, and pipeline wear are reduced dramatically.

Particle size segregation of bulk material in dustiness testers via DEM simulation

ABSTRACT Dustiness testers are used to quantify the level of dust within a bulk material. The generation of dust can occur as a result of many bulk material handling activities, including filling or discharge from storage bins, during free-fall, material impact on conveyor transfers, or impact with other materials. Dust generation can have a serious impact to the environment as well as workers and nearby communities. This paper presents the findings of a discrete element modeling (DEM) study of the flow behavior of a range of binary granular mixes tested in the European Standard and the Australian Standard dustiness testers. Due to current computing limitations, a nondusty material has been chosen for these simulations to determine the underlying characteristics of particle migration within the rotating drums. A range of simulations have been performed using different starting positions of the simulated test product within the rotating drums to determine if this has any overall effect on the particle interactions. Additionally, simulated binary mixtures containing varied size ratios of the same product have been used in an attempt to uncover possible trends, especially in terms of axial and radial segregation.