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Slurry pump mechanical seal failure cause analysis land solutions
Time : 2019-07-26 Hits : 309
one:
Mechanical
seal with less leakage, low energy consumption, long life and other
advantages, the use of a wide range, in recent years has been widely
used in pump shaft seals and other equipment, mechanical seal technology
continues to improve, more and more also has a high reliability,
Improve the power, metallurgy, mineral processing and other users of the
use of mechanical seal experience and confidence, so that the
application in the pulp pump continue to be promoted. However, because
the slurry pump has a mechanical seal structure is complex, requiring
high precision machining, installation technology, etc., due to the use
of harsh working conditions, containing solid particles, corrosion and
wear, so the slurry pump mechanical seal caused by the equipment failure
rate is very high, Once the mechanical seal fails, it will cause the
machine to stop working. Comprehensive analysis and machine seal failure
causes correct and timely take appropriate precautions and corrective
measures accurate troubleshooting is the key and reliable operation of
the slurry pump.
Second, assembly leakage fault:
Mechanical
seal installation problems, dynamic, static ring face shall not have
deformation, cracks, scratches, dust or impurities friction with the
surface before installation or installation process, balance spring
force to face inequality can lead to mechanical seal failure, good
mechanical seal installation, the general to carry out static pressure
test. Observation of leakage. Such as small leakage, the greater the
dynamic or static, the leakage of the sealing ring, indicating that the
dynamic and static ring friction problems. In the preliminary
observation, judgment, leakage, observation of manual turning, for if
leakage, no significant changes in C, statistical dynamic sealing
problems, such as leakage has obvious changes, the conclusion can be
drawn that is dynamic and static direction injection of leakage of the
friction pair, the annular sealing ring problems from the surrounding
water, jet cooling holes or leakage of the leakage of the medium, more
static seal failure. In addition, the leakage channel can also exist at
the same time, but generally speaking, there are primary and secondary
differences, as long as careful observation, familiar with its
structure, can correctly judge.
Mechanical seals assembly should pay attention to the following three problems:
1)
amount of spring compression, moderate, large compression spring can
lead to rapid wear friction and excessive compression spring
instantaneous loss lose the ability to adjust ring face, resulting in
seal failure, excessive amount of spring compression will lead to
fatigue failure, the deformation of the sealing ring, sealing effects.
(2)
seal tight ring seal ring too loose or too tight, will aggravate the
wear between the sealing ring and the shaft sleeve, the early leak, will
also increase the axial adjustment, when moving ring resistance
changes, the state can not be timely adjustment.
(3)
to avoid static sealing too tight, static ring seal is basically in a
static state, the difference is relatively tight, the sealing effect
will be better.
Static
ring is too large, easy to cause static seal ring deformation is too
large, affect the static ring material for silicon carbide sealing
effect,
Generally
brittle, too much stress is easy to cause fracture, static ring is too
tight, will cause difficulties in installation and disassembly, easy to
damage the static ring.
Third, test run leakage:
Slurry
pump mechanical seals, after static test, the operation of high-speed
rotating centrifugal force, will inhibit the leakage of media.
Therefore, the mechanical seal leaks during the test run, and the
sealing failure of the end cover of the shaft is largely due to the
failure of the friction joint due to the damage of the dynamic and
static friction ring. Mainly include:
(1)
when operating, at this time, cavitation and pressure anomalies, such
as large axial forces, are caused by static and dynamic ring contact
surfaces.
(2) when the
mechanical seal is installed, it causes a large amount of compression on
the ends of the friction pairs, causing severe wear and tear.
(3) ring too loose or too tight, the number of spring can not adjust the axial floating ring.
(4) when the static ring is loose, the axial floating ring and the static ring ring remain.
(5)
in the working medium, there are granular materials, into the friction
pairs, destruction of moving ring and static ring seal.
6 design selection, sealing surface pressure is low or cold sealing material is larger.
The
above phenomenon often occurs in the trial operation, and sometimes can
be adjusted by appropriate static ring elimination, but most need to
disassemble, replace the seals.
Fourth, in normal operation, the sudden leakage of fault
The
mud pump leaks suddenly during operation. A few of them are caused by
normal abrasion or service life, but mainly due to the change of their
working conditions or improper operation. The main reasons are as
follows:
(1) time, cavitation or longer pressure output, resulting in sealing damage.
(2)
the actual pump output is too small, a large number of media in the
pump cycle, heat accumulation, resulting in medium vaporization, leading
to sealing failure.
(3) sealed cooling water.
(4) long-term shut down and restart without manual turning, the sealing surface friction due to adhesion and pull bad.
(5) moderately corrosive, polymerizable and colloidal substances increased.
6. Sharp changes in ambient temperature.
All landlord conditions are constantly changed or adjusted.
Today, a sudden power outage or shutdown, etc..
In
normal operation, the sudden leakage of centrifugal pumps, if not found
in time, often have greater accidents or losses, should be paid
attention to, and take effective measures. The cooling water to satisfy
the mechanical seal of the mud pump, often the pump before use, you must
first open the seal water after 5 minutes, stop the pump, can be
closed, because the cooling water and the engine combustion accidents
often occur, users need to pay special attention to. The pump caused by
frequent start or sudden loss of power line in the mud flow, pump
pressure increased sharply, resulting in the mechanical seal ring
opening, so that the mechanical seal failure, the mechanical seal
mechanical seal factory design, fully considered by these factors, to
avoid the blackout. The pump must be shut down for a long time, the seal
cavity and machine cleaning with water pump should be started before
the shutdown, manual turning, confirming that no adhesion friction.
Five, wear corrosion failure
As
a result of the presence of abrasive particles in the slurry pump, the
mechanical seal is generally used in the slurry medium as follows
Risk type:
(1)
wear of seal. As the particle surface penetrated into the end surface,
the abrasive effect was produced, and the wear of the sealing surface
was accelerated.
(2) the
side that the particle of the medium is blocked. Because of the
accumulation of particles, the bridge blocks the movement of the
springs, pins and auxiliary seals, resulting in a decrease in the
floatability of the tracking and compensating loops.
