Kraeva E.M.
Siberian State Aerospace University, Russia
High-efficiency pumps for oil transfer
Under extreme
conditions of continuous growth of oil production in northern areas of
Krasnoyarsk region, fleet of pumping equipment is expanding. Historically, this
industry mainly uses foreign equipment. This is centrifugal submersible
electric pumps (over 45%) with impellers of the closed type. A particular
challenge is the problem of pumping oil spill of taiga wetlands volumes with a
high content of sand, clay and other impurities, as energy and performance
characteristics pumps are greatly reduced with simultaneous the erosive wear of
the impeller.
There is the
need for creation of new generation of centrifugal pumps (CP) with the flow
part of the half-open impeller providing pumping pseudoplastic and viscous
fluids containing substantial (up to 40% by volume) various impurities,
including mechanical. This causes the development of scientific basis and
calculating jet-vortex flow in the half-open impeller pump, which differs from
the flow in the closed channel impeller decelerating the flow of high
viscosity, particularly in the form of suspensions.
The analysis
of the energy balance in a CP with the semi-open impeller allowed revealing
features of the balance of the energy losses in the pump with the release of
the components of certain types of losses. In conducting the balance tests, the
energy characteristics of the CP were determined simultaneously, that vary over
a wide range; that is of great practical and scientific interest. For example,
only end clearance between the blades and the pump body is changed in various
combinations of impellers from 0.25 to 3 mm.
Figure 1 – Balance
of energy losses and characteristics of the CP with the semi-open impeller
(
mm; 
mm; 
ìì; 
mm; 
; 
; 
), 
rad/s
Figure 1
shows the energy characteristics and balance of energy loss of one of the
tested CP [1] with a half-open impeller. Subsequent comparative testing and
evaluation of the balance of energy losses in the CP with a semi-open impeller
showed displacement of mode for most hydraulic efficiency of the pump to lower expense. Lack of cover plates
and front gap seal has reduced the consumption of leaks. But at the same
mechanical loss is increased for the impeller because of friction the end face
of the bladed surface. Hydraulic efficiency slightly decreased to 0,699 from
the energy loss due to friction in the flow of fluid through the channels of the
semi-open impeller.
However, there
are considerable losses due to friction of end surfaces of the blades of the
impeller, the amount of which increased due to the removal the part of the
second disc, which led to the value 
= 0.699. The average level of energy characteristics
similar to a CP with a closed impeller can not only be achieved but also
surpassed [2].
It is
advisable to use this class of pumps with centrifugal impeller of the semi-open
type, design of which provides due to the formation in the flow of the
jet-vortex structure of the hydrodynamic flow, that reduces the viscosity of
the oil flow and erosion damage of the pump, increases the efficiency of
supply, and hence increase its life with reducing operating cost and
maintenance service.
This work was supported by the grant of the
President of the Russian Federation ÌÊ – 1371.2013.8.
References
1. Kraeva E.M. High-speed
centrifugal pumps: Monograph / SibSAU. – Krasnoyarsk,
2011. – 212 p.
2. Kraeva E.M., Kraev M.V. Improving
the energy performance of centrifugal pumps with semi-open impeller // Vestnik SibSAU. – 2009. – Vol. 4 (25). – P.
107-110.