1 Copyright © 2003 by ASME
Proceedings of FEDSM’03
4TH ASME_JSME Joint Fluids Engineering Conference
Honolulu, Hawaii, USA, July 6-11, 2003
FEDSM2003-45745
NUMERICAL SIMULATION OF SAND EROSION
IN STEAM / WATER SEPARATOR
KATO, Susumu
Graduate School of Mechanical Engineering,
Tokyo University of Science
Tokyo, Japan
E-mail: j4502606@ed.kagu.tus.ac.jp
TODA, Kazuyuki and YAMAMOTO, Makoto
Department of Mechanical Engineering,
Tokyo University of Science
Tokyo, Japan
E-mail: yamamoto@rs.kagu.tus.ac.jp
SHITO, Motoaki and KAWAI, Masafumi
Ishikawajima-Harima Heavy Industries Co., Ltd.
Yokohama, Japan
E-mail: masafumi_kawai@ihi.co.jp
ABSTRACT
This paper presents an investigation into a phenomenon
that happened on the wall surface of a Steam / Water Separator
(SWS). It was reported that erosion caused from unknown solid
particle took place on the SWS wall. In order to capture this
sand erosion phenomenon numerically, the SWS flow field was
solved, and then particle trajectory and wear quantity were
calculated, based on the CFD results. Several wall and particle
materials and also the combinations of them are assumed.
Furthermore, the particle diameter was varied from 10
-6
to 10
-2
m. The numerical results insist that the particle, which could be
the factor of the phenomenon, is limited in its diameter range
and its material. The present study will be an aid to clarify the
cause of sand erosion in a SWS.
INTRODUCTION
A Steam / Water Separator (below SWS) is today widely
used in a power plant, for the purpose of separating steam and
water of the two phase flow. In a SWS, the liquidized and
gaseous components in the steam are separated, making use of
the difference of centrifugal force caused by the swirling
motion, and finally the liquidized component is collected and
removed. It was reported that a solid particle incidentally mixed
into the steam caused the sand erosion to a SWS. In the
present study, sand erosion phenomenon in a SWS is
investigated by simulating the turbulent flow field and the
trajectory of a solid particle. To reproduce the strongly swirling
turbulent flow in the SWS, Reynolds stress turbulence model
(RSM) is employed. Using the Neilson-Gilchrist model, the
wear quantity on the inner surface of the SWS is estimated.
Several wall and particle materials and also the combinations of
them are assumed. Furthermore, the particle diameter was
varied from 10
-6
to 10
-2
m. Through this study, it is shown that
the particle, which could be the factor of the phenomenon, is
limited in its diameter range and its material.
NUMERICAL MODELS AND PROCEDURE
As the treatment of two-phase flow, we applied the
one-way coupling method, that is, the motion of dispersed
phase (i.e. particle) is affected by continuous phase (i.e. gas),
while continuous phase is not done by dispersed phase. Thus,
the Lagragian approach is reasonably introduced into the
computation of particle motions traveling on the velocity field
solved by the Eulerian approach.
Flow Field
The flow in a SWS is considered to be zero gravity,
axisymmetric, incompressible and turbulent. Accordingly, the
flow field can be reproduced, by solving the time-averaged
continuity and Navier-Stokes equations expressed as:
and 0
j
j
x
U
(1)
,
1
j
j i
i
j
j
i
j i
i
x
u u
x
U
x
U
x x
P
Dt
DU
(2)
where