Analysis of the Combined Cyclone and Filter Cartridge Separator for

a Hazardous Materials Rescue Truck

Yu Wang

, Shuwen Zhou

and Siqi Zhang

College of Mechanical Engineering and Automation, Northeastern University, Shenyang Liaoning 110819, China;

School of Transportation Engineering, Shenyang Jianzhu University, Shenyang Liaoning 110168, China

Key words: Hazardous materials rescue truck, combined separator, separation efficiency, two-phase flow

Abstract: In accidents during the transportation of hazardous materials, it is necessary to filter the collected substances

when a hazardous materials rescue truck is used to collect the hazardous materials; this method is

sometimes called gas-solid separation. There are many devices used for gas-solid separation. In this paper,

the most commonly used separation devices, namely, the cyclone separator and the filter cartridge, are

combined to form a new filtration device. The advantages of each of these devices are utilized to achieve

effective separation of solid particles and prevent secondary pollution. First, the model of this new type of

separator is built. Next, the model is divided into grids, with an effort to ensure the grid quality is the best.

The model is imported into FLUENT software after dividing the hexahedral structured grid. The Reynolds

stress model (RSM) is selected to simulate the continuous phase, and the discrete phase model is used to

simulate the particle. Finally, the trajectory of the particles is examined and the simulation results are

analyzed.

1 INTRODUCTION

In the handling of hazardous materials from leakage

accidents, the rescue truck first collects the

hazardous materials and then uses the filter

separation device to separate the gas and solids to

prevent secondary pollution. A hazardous materials

storage truck is shown in Figure 1.

Figure 1: Hazardous materials rescue truck.

1.1 Methods of Gas-solid Separation

There are four main types of common gas-solid

separation methods: mechanical force separation,

electrostatic separation, filtration separation and wet

separation(Cen et al., 1999).

The mechanical separation is represented by the

cyclone separator (centrifugal separation). It can be

used under various harsh conditions, such as high

temperature, high pressure and strong corrosion.

Another method is filtration separation, this method

is represented by a filter cartridge type dust

collector, which can effectively capture particles

from 0.1 µm to 5 µm. Wet dust collectors are not

suitable for the separation and filtration of hazardous

Materials and chemical corrosion. Thus cyclone

separator and filter cartridge type dust collector

suitable for hazardous materials storage truck.

1.2 Shortcomings of Cyclone Separator

and Filter Cartridge Separator

The cyclone separator can be used under various

harsh conditions, but it is very inefficient in

separating tiny particles (below 5 µm) because of

the short-circuit flow and the upper ash ring

(Hoffmann et al., 2002).

Filter cartridge type dust collector can effectively

capture particles from 0.1 µm to 5 µm(Gu et al.,

2002). But most of the particles will be removed on

the surface of the filter cartridge. This will increase

the blockage and breakage of the filter cartridge,

Wang, Y., Zhou, S. and Zhang, S.

Analysis of the Combined Cyclone and Filter Cartridge Separator for a Hazardous Materials Rescue Truck.

DOI: 10.5220/0008188102370241

In The Second International Conference on Materials Chemistry and Environmental Protection (MEEP 2018), pages 237-241

ISBN: 978-989-758-360-5

237

resulting in high frequency replacement. Therefore,

the filter cartridge dust collector maintenance fee

will be higher.

2 MODEL OF THE COMPOSITE

SEPARATOR

In this paper, the external structure of the cyclone is

kept and the filter cartridge is added in the exhaust

pipe of the cyclone separator. This approach keeps

the original working characteristics of the cyclone

separator, which can handle 5 µm to 10 µm

hazardous particles. The filter cartridge added to the

exhaust pipe of the cyclone can capture the tiny

particles that cannot be separated because of the

short-circuit flow and the upper ash ring. This

method addresses the shortcomings of the cyclone

separator. Only a small portion of the tiny particles

are captured by the filter cartridge. Most of the

particles are captured by the centrifugal force of the

cyclone separator(Ge et al., 2006). This will increase

the service life of the filter cartridge.

Figure 2: Diagram of the structure of the separator.

The simplify structure of the composite cyclone

and filter cartridge separator is shown in Figure 2.

The proposed separator consists of an air-inlet, a

cylinder, a cone, a dust-outlet, an exhaust-vent and

filter cartridges. The parameters of the model are

shown in the Table 1. The filter cartridge, which is

based on the filter bag, consists of a top cover, a

metal frame, a corrugated frame, a seal ring and a

base. It is repeatedly folded from the filter material

and then combined into a barrel shape. Thus, the

filter cartridge solves the problem of the small filter

area of the filter bag (Zhang, 2015).

Table 1: The model parameters.

air-inlet length(a)

a=160mm

exhaust-vent diameter(D

)

=250mm

dust-outlet diameter(D

)

=200mm

Cylinder height(H

)

=480mm

Cone height(H

)

=640mm

3 THE ESTABLISHMENT OF

THE FINITE ELEMENT

MODEL

3.1 Selection of Meshing Methods

Meshing can be roughly divided into two types:

structured meshing and unstructured meshing(Zhou,

2001). The internal flow field of the cyclone and

filter cartridge composite separator is complicated.

In order to achieve accurate calculations for it, the

entire structure needs structured (hexahedral)

meshing(Hu et al., 2014). Structured grids have the

following advantages.

(1) The calculation accuracy of the hexahedral

mesh is relatively high.

(2) Most of the fits of surfaces or spaces are

obtained by parametric or spline interpolation with

smooth regions that are close to the actual model.

(3) The boundary fitting of regions is easily

achieved, making structured grids suitable for fluid

calculations.

3.2 Meshing Analysis of the Proposed

Model

Because the structure of the cyclone filter separator

is complicated, it will be simplified during meshing.

This simplification will not only reduce the

difficulty of meshing (thereby increasing the quality

of the hexahedral mesh) but also reduce the

complexity of flow field analysis when importing

FLUENT analysis. In this article, the following

processing was performed on the model.

MEEP 2018 - The Second International Conference on Materials Chemistry and Environmental Protection

238

Figure 3: The hexahedral structured grid.

(1) The filter cartridge has much geometric

porosity, making meshing difficult to achieve. Thus,

the geometrical pores are simplified during

geometric meshing, and the filter cartridge is

considered a cylinder. The cylindrical region is set to

a porous medium fluid domain with a resistance

source during fluid analysis(Hu et al., 2017).

Generally, a velocity-dependent momentum is

provided in the porous region; the expression of this

momentum is as follows:

)

(

2 iii

vvCS 







(1)

In the expression,



is the permeability; C2 is

the inertia drag coefficient. The first term on the

right side is the viscous loss term, and the second

term is the inertia loss term.

(2) When establishing the combination model,

the influence of the partial cleaning device above the

filter cartridge is not considered and is omitted

during meshing. The final structured hexahedral

mesh of the model is shown in Figure 3.

4 SIMULATION OF THE MODEL

IN FLUENT

4.1 The Model Calculation Method

Because hazardous materials rescue trucks use

vacuum negative pressure to collect hazardous

materials particles and the collection is two-phase

flow with a particle volume fraction less than ten

percent, in the FLUENT simulation analysis, the

continuous phase flow of the gas is simulated and

then the Lagrangian trajectory method is used to

track the particle trajectory(Hoffmann et al., 2002).

The flow in the cyclone and filter separator is a

complex two-phase flow with three-dimensional

strong rotational turbulence. According to the strong

rotating turbulent flow field of the cyclone and the

porous medium model of the filter cartridge, the

following can be concluded:

(1) The turbulence model selected is the

Reynolds stress model(RSM). It is suitable for high

rotational flow. The Reynolds stress model takes

into account the rapid changes in streamline bending,

vortex, rotation and tension. The Reynolds stress

model has a higher accuracy prediction potential for

complex flows. The transport equations(Zhou, 2001)

for the components of the Reynolds stress are as

follows:









jiji

jikji

uuu

''''











userjijijiji

SFBMG 

,,,,

(2)

In the expression, Di,j is diffusion term, Pi,j is

stress generation term, Gi,j is buoyancy generation

term, Mi,j is pressure strain redistribution term, Bi,j

is discrete term, Fi,j is rotation system generation

term.

(2) For pressure and speed coupling, the

SIMPLE format is selected. Because PISO better

computes the non-steady state situation(Song,2011)

and COUPLED does not apply to porous media,

according to the complexity of the combined model,

the SIMPLE format is chosen for calculation.

(3) Pressure interpolation is based on the

PRESTO format. Because PRESTO is well suited

for high-speed rotary flow and porous media models,

it can better reflect the combined internal flow field

flow.

4.2 Simulation Results

The grid divided in the ICEM software is imported

into the FLUENT software for performing the

simulations used to analyze the problems involving

the new cyclone filter separator. The simulation

results are shown in Figure 4 to Figure 6.

Analysis of the Combined Cyclone and Filter Cartridge Separator for a Hazardous Materials Rescue Truck

239

Figure 4: The pressure contour of the internal flow field.

Figure 4 shows the internal static pressure

contour. The figure reveals that the internal pressure

of the separator is symmetrically distributed and the

pressure on the wall is high. The pressure shows a

decreasing trend moving away from the wall, with

the pressure at the center being small. Simulation of

a single inlet separator in this article results in a

slight oscillation of the pressure above the

dust-outlet. The maximum pressure inside the

combined model is 6.6 times the same size cyclone

separator, and the pressure gradient is 6.8 times the

original.

Figure 5: The speed contour of the cartridge surface.

Figure 5 shows the velocity contour of the filter

cartridge surface. It can be seen that the speed on the

surface of the filter cartridge is relatively high,

whereas the speed near the center of the four filter

cartridges is low. Because the air stream at the

exhaust-pipe is rotating upward, most of the tiny

particles that are not collected by the dust-outlet are

rotated around the airflow and then collected by the

outside surface of the filter cartridge. This process

will cause the filter cartridge on the outer and upper

part to be washed heavily. Here, the appropriate

baffle is selected to reduce this phenomenon.

To analyze the separation efficiency of particles

of different sizes, 9~0.1 µm diameter particles are

selected to be uniformly injected from the inlet.

Figure 6 (a) shows the 9 µm particle trajectory

tracking results, and Figure 6 (b) shows the 0.1 µm

particle trajectory tracking results. The capture rate

of 9~0.1 µm particles reaches 100%. Most of the

large-diameter particles are found to be thrown into

the wall after entering the cyclone separator before

finally falling into the dust exhaust port. These

particles can be directly separated by the structure of

the cyclone separator. In contrast, only a small

fraction of the particles are directly brought from

below the exhaust pipe to the filter cartridge or are

brought to the filter cartridge along with the inner

vortex and then captured by the filter cartridge.

(a) (b)

Figure 6: The trajectory tracking of particles.

5 CONCLUSIONS

The combination of the cyclone and the filter

cartridge in this article retains most of the external

structure of the cyclone, with only four filter

cartridges added to the exhaust pipe. The simulation

results reveal that the proposed separator not only

utilizes the characteristics of the original cyclone

separator (which can better separate 5~10 µm

particles) but also utilizes the characteristics of the

filter cartridge (which can better capture the tiny

particles). An excessive number of filter cartridges

are not added because most of the particles have

been separated by the cyclone prior to the filter

cartridges, and only a small fraction of the particles

will move to the exhaust pipe. Thus, the working

demand of the filter cartridge is not very high. This

MEEP 2018 - The Second International Conference on Materials Chemistry and Environmental Protection

240

proposed combined separator model can better

capture hazardous particles compared to the

individual separators alone.

ACKNOWLEDGEMENTS

Project supported by National Key R&D Program of

China (No. 2017YFC0804805).

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Analysis of the Combined Cyclone and Filter Cartridge Separator for a Hazardous Materials Rescue Truck

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