三国故事的歇后语-王学左派
..
Unit Five
Types of Pipelines
Most
oil
and
gas
pipelines
fall
into
one
of
three
groups,
gathering
,
trunk/transmission
,
or
distribution.
Other
pipelines
are
needed
in
producing
fields
to inject gas
,
water
,
or other fluids into the formation to improve oil and gas
recovery and to dispose of salt water often produced with oil.
Small-diameter
pipelines
within
an
oil
or
gas
field
s
called
flow
lines,
are
usually
owned
by
the
producer.
They
connect
individual
oil
or
gas
wells
to
central
treating,
storage, or processing facilities within the field. Another gathering system made
up
of
large- diameter
lines,
normally
owned
by
a
pipeline
company
rather
than
the
oil
or
gas
producer,
connects
these
field
facilities
to.
the
large-diameter,
long- distance trunk or transmission line. In some cases, individual wells are tied
directly to the pipeline company's gathering system.
Crude trunk lines move oil from producing areas to refineries for processing. Gas
transmission
lines
carry
natural
gas
from
producing
areas
to
city
utility
companies
and other customers. Through distribution networks of small pipelines and metering
facilities,
utilities
distribute
natural
gas
to
commercial,
residential,
and
industrial users.
Flow
lines,
the
first
link
in
the
transportation
chain
from
producing
well
to
consumer,
are used to move produced oil from individual wells to a central point in the field
for
treating
and
storage.
Flow
lines
are
generally
small-diameter
pipelines
operating
at relatively low pressure. Typical flow-line diameters in the United States are 2
in
,
3 in
,
and
4 in. The size required varies
according to the capacity
of the well
being served, the length of the line, and the pressure available at the producing
well to force the oil through the line. Flow lines typically operate at pressures
below
100
psi.
In
many
fields
around
the
world
,
high-capacity
wells
require
larger-diameter pipelines.
Individual oil flow lines are relatively short, typically ranging from less than a
mile to a few miles. However, an oil field containing many wells, each of which is
connected to central facilities by a flow line, can contain several hundred miles
of pipeline in a relatively small geographical area.
The
throughput
of
oil
flow
lines
ranges
from
a
few
bbl/day
upward
,
depending
on
the
capacity of the well being served. Many wells produce several hundred bbl/day, for
..
.
..
instance, and some wells may produce as much as several thousand bbl/day.
Offshore,
relatively
few
flow
lines
are
installed.
For
economic
and
operating
reasons,
most offshore development wells are
directionally
drilled from central platform,
permitting
the
wellheads
to
all
be
placed
in
a
small
area
on
the
platform
.
Individual
wells
therefore
do
not
normally
need
to
be connected by
undersea pipelines to
processing
equipment.
However,
a
few
hundred
offshore
wells
have
been
drilled
remote
from
central
abovewater
platforms
and
are
connected
by
flow
lines
laid
on
the
ocean
floor;
Also,
in
some
cases
a
platform
containing
a
number
of
wells
will
be
connected
by
an
undersea
line
to
a
separate
platform
where
the
oil
is
processed
and/or
stored.
Because oil flow lines are short, the energy (pressure) required to move the oil
through
the
pipeline
to
central
facilities
within
the
field
is
relatively
low.
There
are two types of oil wells those that flow unaided because of the natural energy of
the
reservoir
and
those
that
must
be
pumped.
The
pressure
that
forces
oil
in
a
flowing
well to flow to the surface is usually sufficient to move the oil on to the central
field facility. In wells in which a bottom hole pump must be used to lift the oil
to the surface, the pump's energy also moves the fluid through the flow line.
Additional pumps at points along the flow line are not normally needed.
The
destination
of
most
oil
flow
lines
is
a
tank
battery.
One
or
more
tank
batteries
may be installed in a single field
,
each serving a number of individual wells. A
typical tank battery contains a separator to separate oil
,
gas, and water; a fired
heater to break water-oil emulsions to promote complete removal of water from the
oil; and tanks for storing the oil until it can be shipped from the lease by truck
or
pipeline.
Metering
equipment
is
also
included
to
measure
the
volume
of
oil
leaving
the lease. An additional separator
,
separate meters
9
and other equipment may also
be installed for periodic testing of individual wells.
The
oil
in
each
flow
line
coming
to
the
tank
battery
from
an
individual
well
is
mea-
sured
before
being
mixed
with
the
flow
from
other
wells
for
treating
and
separation.
This information is important for evaluating the performance of the well and the
reservoir.
Other
equipment
may
be
required
at
these
field
facilities
under
special
conditions.
Desalting
facilities
are
needed
if
the
produced
crude
contains
large
amount
of
salt,
and heated storage may be required if the oil is too viscous at low temperatures to
be pumped from lease storage.
Flow
lines
are
normally
made
of
steel,
though
various
types
of
plastic
pipe
have
been
used
in
a
limited
number
of
applications.
Sections,
or
joints,
of
steel
pipe
for
flow
..
.
..
lines
can
be
connected
by
welding
or
by
the
use
of
threaded
couplings.
Other
specially
joints and joining methods aimed at reducing construction time and cost have also
been developed for both steel and other flow-line materials.
Pipe used for oil flow lines is relatively lightweight because operating pressures
are
low.
Wall
thickness
for
a
3-in.
diameter
flow
line,
for
example,
might
typically
be 6. 216 in.
,
corresponding to a weight
of 7.
58
Ib/ft .
Heavier pipe
in the 3-in.
size is available in wall thickness to 0. 437 in. and
in
weights up to 14. 3
Ib/ft
.
Pipeline pipe is usually referred to by its nominal size, 3-in. in this
case .
The
outside diameter of nominal 3-in. diameter pipe is actually 3,500 in.
Some flow lines are coated internally to protect against corrosion. Whether or not
internally coated pipe is used depends on the corrosion potential of the oil
,
the
expected
producing
life
of
the
well
being
served,
and
other
factors.
Where
flow
lines
are buried
,
they are usually
73
页
also coated externally to minimize corrosion.
When
water
and
gas
have
been
removed
from
the
oil,
it
is
in
lease
tanks
for
shipment.
Oil may be trucked from the lease if a pipeline is not available, but this method
is
used
primarily
when
small
volumes
of
oil
are
produced
on
the
lease
and
a
pipeline
is not justified
,
or when a new well is completed and the pipeline has not yet been
laid to the lease.
Oil
leaving
the
lease
must
be
measured,
either
manually
or
automatically.
Manual
mea-
surement
involves
gauging
the
lease
tanks
before
and
after
oil
is
removed.
The
volume
shipped is then calculated. Oil can be shipped from the lease by manually operating
a valve in the storage tank that lets oil flow into a truck or into the pipeline
company's gathering line.
Today,
lease
automatic
custody
transfer
(LACT)
units
are
used
where
significant
oil
volumes
are
involved.
In
this
method,
a
pump
is
automatically
started
when
the
level
in
the
storage
tank
reaches
a
prescribed
height,
and
oil
is
pumped
into
the
gathering
line.
The
pump
remains
on
until
the
level
in
the
tank
is
lowered
to
a
designated
point;
then the pump is automatically shut off. The volume of oil flowing through the LACT
system
is
automatically
measured.
A
sampler
also
measures
the
water
and
sediment
in
the stream so a correction can be made to the volume measurement when calculating
the payment to the lease owner. In fields producing large volumes of oil, shipment
may be virtually continuous from the lease storage tanks.
^
The
next
link
in
the
oil
pipeline
chain
is
gathering
lines
that
transport
oil
from
field- processing and storage facilities to a large storage tank or tank farm where
..
.
..
it
is
accumulated
for
pumping
into
the
long-distance
crude
trunk
line.
These
gathering
system
are
normally
owned
by
the
pipeline
company
that
operates
the
main
trunk
line.
In the United States, these systems typically consist of lines ranging from 4 in.
to 8 in. in diameter. Size, of course, depends on the volume of crude to be moved,
pipeline length, and other factors. Operating pressure is higher than that of flow
lines.
Gathering
system
throughput
obviously
varies
widely
,
depending
on
the
number
of
field
storage
tanks
served and
the
producing capacity
of
wells in
each field.
These
gathering
systems
are
quite
flexible
^
their
capacity
can
be
increased
through
various
methods to accommodate new producing fields in an area or other volume changes
.
The mileage contained in both crude and products-gathering systems in the United
States is reported by the
FERC
to be about 38,500 miles. Though an accurate count
of gathering-system mileage outside the United States is not available, the same
concept is used in gathering oil production.
From
large
central
storage
facilities,
oil
is
moved
through
large- diameter,
long-distance
trunk
lines
to
refineries
or
to
other
storage
terminals.
In
the
United
States,
much
of
this
traffic
is
from
the
oil- producing
areas
of
the
West,
Southwest,
and Gulf Coast to refining centers in the central and upper Midwest and the
U.
S.
Gulf Coast.
This
network
of
crude
trunk
lines
comprises
a
wide
variety
of
pipe
sizes
and
capacities.
Pumps
are
required
at
the
beginning
of
the
trunk
line,
and
pumping
station
must
also
be spaced along the
pipeline
to maintain
pipeline pressure at the level
required
to
overcome
friction,
74
页
changes
in
elevation,
and
other
losses.
The
different
sections
of
the
system
are
sized
to
handle
expected
volumes?
if
new
fields
must
be
tied
in
by
a
new
branch
line
?
the
capacity can often be increased by installing additional pump station.
Crude trunk lines operate at higher pressures than field-gathering systems and are
also
made of
steel.
Individual sections are jointed by welding. These lines are,
in
the
United
States
at
least,
almost
always
buried
below
ground
surface
and
are
coated
on the exterior to protect the steel pipe from corrosion.
Crude oil trunk lines serving the United States can be several hundred miles long.
Control
of
such
a
system
is
a
complex
operation.
Sophisticated
monitoring
and
control
systems have been developed to permit the pipeline operator to fulfill delivery
commitments and avoid a malfunction of the system.
..
.
..
The complexity of these systems varies so widely that it is difficult to select a
typical
system.
The
fact
that
they
traverse
long
distances
complicates
their
construction and operation. Flow lines are usually confined to a single field, and
the parties involved in the decision making and permitting are few. But when a line
must
cross
land
owned
by
many
different
owners
,
most
of
whom
receive
no
benefit
from
the
pipeline
,
just
the
job
of
obtaining
right
of
way,
for
example,
becomes
significant.
Environmental laws also require that many permits be obtained to cross roads and
streams,
pass
through
wildlife
areas,
and
for
other
purposes.
For
example,
about
1,400
permits
had
to
be
obtained
from
various
state
and
f
ederal
agencies
to
begin
construction of a crude pipeline from the West Coast to Minnesota.
The
trans-Alaska
crude
pipeline,
completed
in
1977,
is
one
of
the
most
widely
publi-
cized
examples
of
special
requirements
involved
in
building
a
long-distance
pipeline.
Not only was the permitting process a complex and lengthy one
—
an act of Congress
was required to speed environmental review in the courts
—
but new techniques and
equipment
had
to
be
specially
developed
to
ensure
the
line
did
not
damage
the
sensitive
Alaskan
environment. The possibility of a significant oil spill also had to be
minimized.
It
is
difficult
to
pinpoint
a
typical
throughput
for
an
individual
crude
trunk
line.
The
trans-Alaska
pipeline,
a
48
in.
diameter
line,
is
designed
to
carry
up
to
2
million
b/d,
but
that
volume
is
by
no
means
typical
of
all
systems.
However,
data
are
available
on an
individual
company basis for common carrier oil pipelines. Total deliveries
of crude by those pipelines was reported by the
FERC
as about 6. 1 billion
bbl
in
1981. Those companies operated almost 58
,
000 miles of crude
trunklines.
75
页
Reading Material 1
Types of Operation
Station
operation
varies
not
only
with
the
size
and
type
of
equipment,
but
also
in the
method of moving the oil or products through the line.
The most common types of operation can be classified as in the following
paragraphs
.
A
-
Put and Take Operation
With
put
and
take operation
,
each station draws
from
tankage
and
pumps into tankage
..
.
..
at
the
next
station
;
thus
,
each
station
works
with
tank
head
on
the
suction
side
and
pumps
independently
of
the
stations
either
upstream
or
downstream.
Advantages
of
this
method are$$
(1)A
slow-moving
or heavy oil does not slow
actual delivery until it enters the
last section of the line, provided
that sufficient oil is available in tankage at
stations downstream from the initial station.
(2) It is not necessary to keep all stations in exact step.
(3)
There
is
less
chance
of
moderate
to
high
pressure
on
the
line
on
the
suction
side of the station. No pressure control is necessary on the suction side of the
station.
B.
Float Tank Operation
Some systems pump directly from one station into the suction manifold of the
next .
A
small
tank
,
called
a
float
tank
,
is
open
to
the
suction
line
at
each
station.
This
is
very
similar
to
the
put
and
take
operation:
The
real
difference
is
that
the
capacity
of the float tank is usually small. Unless oil is available in other tanks
,
each
station floating
on the
line
must maintain a pumping
rate approximately
the same
as
the station immediately upstream.
C
Tight Line Operation
When
one
station
pumps
directly
into
the
suction
side
of
the
pumps
at
the
next
station
and no tankage is open to the suction manifold at the intermediate station, it is
called tight line operation. The advantages of this method are:
1.
Highly volatile
crudes
or products are conserved because they are pumped with
a positive pressure at all times.
2.
Increased flow rate of heavy crudes may be obtained by blending with light ends
to reduce viscosity with less loss of the lighter materials.
3.
Evaporation
losses
which
occur
when
pumping
into
or
out
of
tankage
are
eliminated.
4. Investment in tanks at intermediate stations is eliminated.
5.
Commingling
between
tenders
or
batches
is
reduced
to
a
minimum
by
holding
the
flu-
id in the line and under pressure until it is delivered at its destination.
D.
Operating Procedures
The
initial
station
on
a
trunk
line
receives
crude
oil
or
products
from
adjacent
tanks.
It
produces
pressure
required
to
move
the
oil
to
the
next
station.
A
positive
suction
pressure on the main pumps usually is needed and is frequently supplied by booster
pumps close to the tanks.
Where
the
booster
is
close
to
the
tanks
,
in-line
or
horizontal
pumps
are
most
frequently
used.
A
deep
well
pump
or
in
a
can
serves
well
..
.
..
when
one
booster
draws
from
several
tanks
and
must
be
some
distance
from
each.
In recent installations the booster is started by a switch or pushbutton in the
station;
however,
a
manual
lockout
pushbutton
usually
is
installed
at
the
unit
as
a
precaution
against pumping from the wrong tank,
Before starting a main station the operator must be certain that all equipment
is in proper operating condition. Checks which he should make before starting the
unit include
:
1. All fans or blowers should be
operating properly to insure adequate pressure and
ventilation throughout the station.
2. All protective devices should be in service. For example
,
valves in the line to
the pressure switches should be fully opened.
3.
Flow
of
water
should
be
started
in
the
cooling
system
—
bearing
jackets
,
stuffing
box jackets and water quench lines.
4.
The
lubricating
oil
for
all
bearings
should
be
checked
for
level
and
cleanliness.
5. All valves between tanks and the unit to be operated should be checked to assure
an unobstructed flow. Pressure gauges mounted on the
suction
line
or in
the control
room
indicate
the
pressure
on
the
suction
side
of
the
pump.
Caution
must
be
exercised
when opening or closing any valve on the line; a valve in an improper position can
result in serious d
a
mage to the equipment or line or contamination of
crudes
or
products being pumped.
6. Air pressure should be checked to insure that the air supply for the pneumatic
control instruments is in
order .
All
dripwells
and air filters should be blown to
remove moisture or foreign particles from the air lines.
.
7.
Indices
on
the
pressure
control
instruments
should
be
set
to
control
the
pressure
as the dispatcher has instructed.
8.
All
couplings
on
the
units
should
be
checked
for
lubrication
and
to
see
that
drain
or filling plugs are in place.
9. Where a speed
increaser
or reduction gearing is used
,
its oil system should be
checked for level and cleanliness.
These checks apply to station and units in general. In an electrically-operated
station the following must also be checked:
1. Ducts furnishing air to motors should be checked for moisture if the motor has
been shut down for some time and periodically during
operation- every
two or three
weeks in any event.
..
.
..
2.
The
main
station
circuit
breaker
must
be
closed
to
bring
current
into
the
starting
equipment.
When this is accomplished the voltage should be checked to see that it
is of proper value and that it does not vary too much.
3.
Where
switchgear
employs
dc
control
circuits,
the
voltage
must
be
checked.
Insuffi-
cient
voltage
will
prevent
operation
because
the
coil
holding
the
breakers
in
closed
position is energized through this circuit.
4.
Where
the
unit
breakers
are
removable
,
each
section
should
be
checked
to
see
that
the breaker is in proper position and that the circuit to the pushbutton control is
closed.
5.
Where
the
motor
starting
equipment
includes
disconnecting
switches,
they
must
be
closed.
6.
All
automatically-operated
blower
and
valve
starters
must
be
in
the
on
position,
In
an
installation
with
internal
combustion
engines
as
prime
movers
the
operator
must
be certain that
:
1. Cooling water is circulating properly.
2.
The
lubricating
system
is
primed
and
contains
enough
clean
oil
of
the
proper
grade;
the filters or purifiers are not clogged
;
and the flow of the cooling
agent to the heat exchanger is not obstructed.
3. All moving parts are free and well lubricated.
4.
The
fuel
oil
system
to
the
engines
is
clean
and
primed.
Put
the
fuel
pump
control
in the
on
5. All parts are in the
clear^
and there is no water in the cylinders. This is done
by turning the engine over several revolutions with the air jack.
6. The exhaust manifold is drained.
Where air injection is used on an engine
;
1. Bleed the air system and engine air compressor.
2. Blow the air bottles to the engine to clear the line of any fuel or gas.
3. Open bleeders on low and intermediate stages of the air compressor. This will
relieve the load on the engine until it is going the required
speed
and will clear
the compressor
of
any fuel oil or gas which has leaked into it. (If an engine fails
to start
,
be certain valves on the starting and injection air lines are closed, and
that
the
air
is
bled
out
of
these
lines,
as
outlined
above,
before
attempting
to
start
the engine again
)
4. Pump up air-starting tanks.
5. Test air lines.
6. Test cylinder valves and piston
^
rings
w
ith air. If there is any blow-by in the
..
.
..
cylinder, lubricate it thoroughly.
Where
a
small
auxiliary
engine
is
used
to
start
the
large
engine,
it
should
be
warmed
up for several minutes before the clutch between it and the large unit is engaged.
A piston or plunger pump must be checked to see that:
1. The by-pass valve from discharge to suction is fully opened.
2. The suction and discharge valves on the unit are open.
3. All lubricators are feeding oil properly.
In addition to checks of the lubricati
o
n and cooling systems
,
a centrifugal pump
should be checked to insure:
1. The by- pass valve around the main unit discharge valve is open.
2. All valves in the seal oil system are in the correct position.
3. The bleed-off valve from the stuffing box is open.
4. The main unit suction valve has been opened.
5. The case has been vented to remove all gas or vapors.
E.
Starting the Units
After the dispatcher has issued orders to start the unit
,
the operator proceeds
according to one of the systems described below.
In
an
engine-driven
station
where
air
starting
is
used
?
the
operator
opens
the
valve
from the starting air tanks and allows it to enter the cylinders equipped with air
valves. The engine begins turning and the other cylinders fire. At this point the
operator
closes
the
air
valve
and
all
cylinders
fire.
The
engine
is
now
in
operation.
In an electric station where reduced-voltage starting is used
?
a motor is started
by closing the starting switch with a hard, firm stroke on the lever. This position
is
held
until
the
motor
comes
up
to
speed
?
as
indicated
by
the
ammeter
dropping
back
to
a
normal
reading.
Then
the
run
lever
is
pushed
firmly
into
position.
If
manual
the
line
starting
is
used
?
it
is
necessary
simply
to
close
the
breaker
firmly,
admitting
line
voltage
to
the
motor.
In
magnetically-operated
starters
?
it
is
merely
necessary for the operator to push the start button.
The unit now comes up to speed but it is not yet carrying the load.
To start the oil in the line in a reciprocating pump installation, the by-pass
valve
is
slowly
closed
:
this
forces
oil
into
the
discharge
line
and
loads
the
engine
or
motor.
It
may
be
either
completely
closed
or
it
may
be
closed
to
the
position
which
by- passes enough oil to establish the desired pressure or flow. Where an automatic
control
valve
is
also
installed
in
the
by-pass
line
?
the
manually-operated
valve
is
fully opened because the control valve will automatically by-pass enough oil to
establish the
pre-set
pressure conditions.
..
.
..
A centrifugal pump is started against a closed or nearly closed discharge valve
;
therefore
the
valve
must
be
opened
slowly
to
start
oil
moving
in
the
line
and
to
keep
oil in the pump case and from overheating or vaporizing and to prevent the case and
impeller
wear
rings
seizing
and
locking
the
rotating
element.
As
the
discharge
valve
is opened the engine or motor is loaded while the flow gradually increases. When a
control
valve
is
located
in
the
discharge
line
the
flow
is
regulated
with
this
valve
and the discharge valve need not be opened so s
l
owly. The control valve should be
almost closed
?
either manually or automatically
?
when the
u-nit
is coming on the
line. This will prevent overloading the driver
?
surges in the line and
?
in the case
of
an
electric-motor-driven
pump,
excessive
power
demands.
After
the
unit
is
on
the
line the control valve should be opened smoothly so as to match the station with
existing line conditions.
The pumping unit should be checked to see that all lubricating and cooling systems
are operating properly; that stuffing boxes or mechanical seals are not leaking
excessively; that all oil rings are turning freely; and that the units are not
vibrating too much.
81
页
Reading Material 2
Station Operation
A. Pressure and Flow Variations
In
put and take
viscosity
?
pressure at the upstream station will not change unless throughput is
changed or tank head at the receiving station varies. Stated differently
,
the loss
in
pressure
from
the
upstream
station
to
the
downstream
station
is
constant.
If
crudes
of a variety of viscosities and gravities are in the line
,
considerable pressure
variations
will
occur
—
the
average
viscosity
and
gravity
determine
the
friction
loss
;
if centrifugal pumps are used
,
the discharge pressure rises with each increase in
specific gravity and the converse is true. If the viscosity does not exceed 70 S
U
S
.
it will have little direct effect on the performance of the pump. The direct effect
of an increase in viscosity is a gradual increase in friction loss in the line. If
the station is operating at maximum pressure, the flow will decrease, producing an
increase in case pressure and initiating a throttling loss equal to the difference
between case
and discharge
pressure.
Where
float
tanks
are
open
to
the
suction
side
of
each
station?
the
result
of
a
change
in
viscosity
or
gravity
is
very
similar
to
that
in
put
and
take
operation.
The
amount
..
.
..
one station can out- pump other stations on the line is determined
by the capacity
of
its
float
tank
and
the
difference
between
its
flow
rate
and
the
rate
of
the
station
slowed by the heavier oil.
To clarify float tank operation examine the two-station line. If oil of uniform
viscosity and gravity stretches from the first station through the second station?
pressure
and
flow
conditions
are
constant.
If
a
heavier
oil
enters
the
first
station?
flow
rate
out
of
the
station
begins
to
fall.
It
will
continue
falling
until
the
headend
of
the
heavy
batch
reaches
the
next
station.
Throughput
of
the
station
will
then
become
constant at the slower rate. However? the quantity of flow is reduced and will not
increase
until
the
tail-end
of
the
heavy
batch
passes
the
first
station
and
a
lighter
oil begins filling the line downstream from the
initial station.
The
flow will then
steadily
increase
until
the
line
is
filled
with
the
lighter
oil.
During
the
time
the
first
station's
flow
dropped?
the
second
station
was
able
to
continue
pumping
at
the
higher
rate
until
it
had
depleted
the
float
tank
or
until
the
heavy
batch
filled
the
section
of
line
downstream
from
the
second
station.
At
this
time
the
flow
would
fall
in
step
with
the
first
station.
Effect
on
the
flow
would
be
the
same
as
that
resulting
from its arrival at the first station; however? since the first station would then
be able to out-pump the second station? the float tank at the second station would
receive
the
surplus
throughput
and
thus
prepare
the
second
station
for
the
next
batch
cycle.
In
tight-line
all
stations
must
operate
at
the
flow
rate
of
the
slowest
station.
Since
centrifugal
pumps
are
normally
used
for
this
type
operation,
oil
gravity
and
viscosity
changes
83
页
produce the results described below.
If the initial station is pumping a uniform light oil and the liquid between the
stations
is
of
similar
viscosity
and
gravity
,
the
pressure
drop
between
the
stations
is
constant.
As
soon
as
a
heavier
oil
enters
the
initial
station
the
centrifugal
pumps
will develop more pressure
;
this will step-up flow if the station is not already
operating at its pressure limit. In the event the station is operating at maximum
discharge
pressure,
the
increased
head
must
be
throttled,
resulting
in
an
increased
load with no increase of flow. This illustrates the importance of having at least
one
pump
in
the
station
which
will
develop
less
head
than
the
other
pumps.
Then
when
the heavier oil enters the station the smaller pump can be brought into service
to
replace
a
large
one,
thereby
eliminating
the
power
lost
in
throttling
the
excess
head
through
the
control
valve.
In
engine-driven
stations,
the
same
purpose
can
be
achieved
..
.
..
by
speed
regulation.
The
reduction
in
throughput
at
this
station
affects
all
downstream stations because their suction pressure drops; if they are operating at
minimum
suction
pressure
they
also
must
throttle
to
hold
this
minimum
suction
pressure.
The station upstream from the slow station will increase in discharge pressure as
well
as
increase
in
suction
pressure
;
their
flow
rate
has
been
slowed
and
they,
too,
will begin throttling when they reach maximum line pressure. The stations may be
operating
at
a
pressure
which
is
low
enough
for
the
increase
in
pressure
not
to
exceed
the
maximum.
Then,
the
net
effect
will
be
an
increase
in
flow
until
the
friction
loss
because of the heavier oil counteracts the increased head.
B.
Frequent Inspections
The
operator
should
remember
that
it
is
his
responsibility
to
protect
the
investment in station and line equipment. He should check frequently all factors
influencing operation of the station. The useful life of equipment can be greatly
reduced by oversight or carelessness.
In addition to maintaining a constant check of line pressures and flow rates
,
the
station operator must be certain that all equipment is functioning properly and
constantly be alert for any indication of trouble in the station. At least hourly
he
should
inspect
bearings
,
packing
glands
or
mechanical
seals,
pressure
lubricating
systems
and
cooling
systems
on
the
pumps.
On
electric
motors
the
operator
should
check
the
voltage
and
the
amperage
being
drawn
by
the
unit,
the
temperature
of
the
bearings
and the temperature of the coils, if this indicating equipment is installed. In an
automatic or push-button system, the unit should be checked through its
start and
stop
sequence
periodically.
A
test
position
is
usually
provided
in
control
circuits
to enable the electrician to check the system without starting the motor.
The
operator
in
an
engine- driven
station
should
inspect
the
engine
thoroughly
every
hour, noting the water outlet temperature and the lubricating oil pressure at each
cylinder.
Exhaust
from
the
engine
should
be
clear
and
the
exhaust
temperature
should
be about what is shown on the
nameplate.
A cloudy exhaust
,
except when the engine
is
overloaded
,
is
the
signal
that
the
engine
is
functioning
improperly.
One
or
several
cylinders
may
be
operating
with
leaky
fuel
nozzles,
piston
blow-by,
a
dirty
air
filter
or
fouled
valves;
the
cloudy
exhaust
indicates
incomplete
combustion.
The
compressor
on an air injection engine should be
84
页
checked hourly and moisture or oil in the system should be blown out.
Instrument
air
compressors
and
air
tanks
should
be
checked
frequently
for
moisture
..
.
..
and leakage.
If a boiler is used to heat the station
,
the operator should check regularly to be
sure it is functioning properly. He should endeavor to hold an even water level in
the
boiler.
If
water
drops
below
sight
in
the
gauge
glass,
he
should
immediately
test
the lowest cock, if water does not appear, the fuel and feed water should be shut
off until the boiler has cooled.
Once
each
shift
the
operator
should
blow-down
the
boiler
gauge
glass
and
be
sure
the
water returns freely to the glass, he should test the cocks to see that the gauge
glass
indicates
the
true
level
of
the
water,
and
he
should
lift
the
seat
of
the
safety
valve by means of the lever or pull cord to be certain it is functioning properly.
Some practices which should be followed in boiler operation are:
1. The boiler should be blown down at regular intervals.
2. Steam pressure should never exceed that allowed by the boiler inspector.
3. The safety valve should be checked at least every two weeks to see that it blows
at the set pressure.
4.
Boilers
should
be
lighted
only
with
a
torch
extension
of
sufficient
length
to
permit
the operator to stand well in the clear and to one side of the firebox door in case
of a flare-back.
5. When taking the boiler out of service for the summer, turn the fuel off, let the
boiler cool, drain and flush out scale and settlings, remove inspection plugs and
dry out remaining water with a rag for a wick with its lower end in a bucket. Clean
soot out of flues with a flue scraper. Coat the flues and end plates where soot is
removed with an oil and graphite mixture to prevent rusting.
C.
Dispatching Orders
The
dispatcher
coordinates
operation
of
the
stations
and
tanks
in
order
to
move
the liquid petroleum through the line on schedule. The arrangement should reduce
commingling between adjacent batches. To accomplish his task, the dispatcher must
rely on the men who actually control the station operations. For this reason, it is
essential that there be cooperation between operators and dispatchers.
Dispatching orders govern starting or stopping of units, raising or lowering of
pressure,
opening
or
closing
of
important
valves,
utilization
of
tankage
and
sampling
of
oil.
These
orders
may
be
transmitted
by
telegraph,
teletype,
telephone
or
radio.
The operator should record all orders, other than minor pressure changes, on the
station log sheet. Operating orders and reporting leaks take precedence over other
messages.
..
.
..
The dispatcher should be informed by the operator of abnormal conditions, such
as pipeline or machinery failure, requests for shut- down time so that repairs may
be made, power failures and many other unpredictable occurrences. In an emergency
or abnormal operating condition, the dispatcher has full charge of operation and
issues
orders
accordingly,
since
he
has
an
overall
picture
of
operating
conditions.
85
页
D.
Sampling and Testing Oil and Products
In
pump
station
operation
gravity
and
temperature
readings
of
the
oil
are
often
required
by the dispatcher to verify
progress through the line and to make accurate
cuts
between
batches.
These
readings
can
be
taken
automatically
,
or
they
may
be
read
from
a hydrometer. Dye plugs
may
be injected between
batches
of similar
products
to
provide a visual check of batch change at the receiving station or terminal.
It
is important that sampling or testing equipment be kept clean
and in good
working condition. A periodic calibration will assure accuracy.
Periodic
thiefing
of
stock
and
working
tanks
is
necessary
to
determine
the
level
of
basic
s
ediment
and
water.
When
a
crude
oil
tank
is
being
filled
or
emptied,
a
sample
of oil should be taken at regular intervals to determine the suspended BS
&.
W in the
stream.
Transportation
of
refined
petroleum
products
requires
an
elaborate
system
of
controls,
laboratory as well as operational
,
to insure that shippers receive their products
according
to
specification
s
.
Continuous,
detailed
checks
of
products
being
transported are necessary. This work is done in laboratories of the transportation
companies. Similar checks are made
by
shippers.
E,
Stopping Sequence for Units
An engine may be stopped by closing a valve in the fuel line or, in the case of a
spark-fired engine
,
by opening or grounding the electrical firing circuit. Cooling
water and oil to the engine should not be cut off until the outlet temperature has
dropped to within 5 to 10 degrees of the inlet temperature
^.
For an extended engine
shut-down,
the
water
jackets
should
be
completely
drained
to
prevent
rusting
and
to
eliminate any danger from freezing. The air injection valves on an engine of that
type should be left open until the engine comes to rest. This will insure the
combustion
of
all
fuel
pumped
into
the
cylinder
and
will
clear
the
atomizer.
The
valve
on
the
air
injection
bottle
should
be
closed
and
the
bleeder
on
the
compressor
should
be
opened.
Do
not
place
an
engine
in
starting
position
until
ready
to
operate
it
again.
..
.
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
三国故事的歇后语-王学左派
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