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|Title: ||Investigation of dust explosion phenomena in interconnected process vessels|
|Authors: ||Roser, Markus|
|Issue Date: ||1998|
|Publisher: ||© Markus Roser|
|Abstract: ||It is well known that where-ever combustible dusts are handled, or result as a waste
product, unwanted ignitions and explosions can occur. Dust explosions present a high
potential risk in the process industries. The past has shown that, in the European Union,
more than 2,000 dust / air or gas / air explosions occur each year. In Germany alone the
damage of dust explosions costs more than £ 16,000 per day.
A lot of fundamental research work on dust explosion has been done for single vessels
however, in reality, vessels are normally connected via pipes to other process vessels.
To prevent secondary vessel explosions, and to protect interconnected vessels from the
effects of explosions, further research into these complex phenomena is required.
This research work concerns the investigation of dust explosion phenomena in
interconnected vessels. Large scale tests were conducted in which I m' or 4.25 m'
process vessels were connected via a pipe to a realistically filled 9.4 m' vessel. Pressure
transducers were placed in the vessels and along the pipe, also photo diodes, positioned
along the pipe, were used to measure the pressure development and the flame front
velocity respectively. In further investigations the process vessels were connected to an
open ended pipe. It was possible to estimate, with the aid of a CCD camera, the flame
shape and flame length of the emerging flame jet dependent on the explosion course at
the process vessel.
The results have shown that, under different circumstances, dust explosion propagation
from the primary process vessel through the connecting pipe which reaches the
secondary silo as a flame jet, may ignite a dust / air mixture and thereby initiate a secondary dust explosion. The expected reduced explosion over-pressure of such a
secondary dust explosion may be much higher than in case of a single vessel explosion.
For the first time an empirical mathematical model for calculating the flame front
propagation time inside a connecting pipe after a dust explosion in a connected
explosion vessel has been developed. The model is validated for dust and gas explosions
in different vessels, independently of whether the explosion vessels are vented or closed
and for different diameters of the connecting pipe.
A numerical simulation model for dust explosions in closed spherical vessels was
written in a C comparable language which runs under Windows 3.11 and Windows 95
on a standard PC. The validation of this numerical model is in good accordance with
measurement results of real dust explosions. The model shows good agreement with
data from explosions in closed vessels for maize starch, aluminium and magnesium
dusts and propane gas. In vented vessels in some cases for maize starch good agreement
is also shown.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Mechanical, Electrical and Manufacturing Engineering)|
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