1 steam drum water level survey importance
The maintenance steam drum water level is guarantees the
boiler and the steam turbine safe operation essential condition in the
certain scope. The steam drum water level excessively is high,
directly affects the soft drink separation the effect, causes the
saturated steam humidity to increase, the salt content increases.
When water level as high as certain degree, the steam must
including water, but in the water 含盐 the density far compared to
steam high, causes the steam quality to worsen, the salts on the
superheater pipe wall the scaling, will cause the superheater tube to
burn out, the demolition, will be serious when will be able to cause
the steam turbine to enter the water. If the steam drum water
level excessively is low, then destroyed the boiler soft drink natural
circulation, causes 水冷壁管to burn out, seriously lacks when the
water also can have accident and so on cartridge igniter.
Therefore, the steam drum water level measuring instrument
application is guarantees the afterheat boiler stable safe operation
the important link.
2 several kind of steam drums waters level measuring instrument
application introduction
At present, the afterheat boiler steam drum water level
measuring instrument mainly has following 3 kinds: Double color
水位? differential pressure type 水位计and electrode type
水位?
2.1 pair of colors 水位?
Uses the connecting principle to make, demonstrates the
boiler water vapor through optics principle to be partial all is
colored, the steam assumes red, the water assumes the green.
This kind 水位计belongs to the boiler the appurtenance,
installs. Direct observation water level, steam red duck, steam
Man Quanhong, Shui Manquan green, is automatic along with the water
level change but continuously. Opens when the boiler, stops uses
to monitor when steam drum water level and normal operation regularly
proofreads other patterns 水位? Double color
水位计observation obvious direct-viewing, but in actual movement,
because the boiler adds the medicine corrosion and the water vapor
washes out, moves after period of time, the quartz glass tube
endophragm attrition is serious, causes the soft drink dividing line
not to be obvious. Especially now generally uses the closed
circuit TV surveillance, scene 摄像?is caused the water level
demonstration even more 模糊不清 the light change influence,
moreover because 水位计is in on the steam drum, the ambient
temperature is high, causes 水位计the illumination maintenance work
load obvious increase.
2.2 differential pressure types 水位?
According to the hydrostatics principle, through between
the survey change water level and the constant water level
differential static pressure, presses the difference the value to
transform into the water level value, again changes delivering through
the difference pressure to transform the steam drum water level into
the electrical signal which continuously changes along with the water
level, took automatically gives in the water control system the
important parameter.
In the practical application the differential pressure type
水位计existence question is: When survey boiler steam drum
water level, the dome pressure change causes "the water level 3
difference pressures" the relations also change, thus brings the very
big error to the survey. Now generally uses has the dome
pressure compensation the balanced vessel measuring technique, but its
accuracy still received the very big limit. Because the design
calculation balanced vessel compensation system is in the zero water
level situation according to the water level to obtain, when moves the
boiler water level deviation zero water level, can cause the measuring
error. When the steam pressure suddenly drops, in the positive
pressure vessel condensing water is evaporated also can cause the
meter display to be abnormal. These all give the boiler movement
operation to cause the very major difficulty, especially invests
automatically for the water adjustment when will have the malfunction,
will cause the boiler accident to occur. Differential pressure
type 水位计quite suitablly to boiler stable movement time water
level survey, when the movement parameter change very big error very
is also big. Therefore in the actual movement avoids as far as
possible presses on the measurement system works (for example dumps
pollutants, verification and so on) when the difference. When
must work, must relate with the boiler operator, reduces as far as
possible to the difference presses the survey the influence, for
example, in the 2nd kiln afterheat boiler movement initial period,
once because the balanced vessel demolishes the heat preservation in
the difference pressed 水位计to cause the steam drum water level to
instruct wrongly had the boiler accident (because beforehand not to
relate with boiler movement personnel, automatically has not relieved
for aqueous system).
2.3 electrodes types 水位?
Uses the saturated steam and the saturated steam
condensing water conductivity difference, 非电?the boiler water
level change transforms into the electrical signal, and takeoffs the
demonstration water level by two measuring appliances long ranges.
The electrode type 水位计basically has overcome the dome
pressure change influence, might use in the boiler to open stops and
变参?in the movement. Electrode type 水位计to steam drum
very near, the electrode to two measuring appliances completely is the
electric signal transmission, therefore this kind of measuring
appliance not only delay slightly moreover the error to be small, does
not need to carry on the erroneous computation and the adjustment,
causes the measuring appliance the overhaul and the verification
greatly is the simplification.
In the practical application, the electrode type 水位计water
level survey is off and on, and to the water level vessel choice which
connects with the steam drum must be suitable, reduces the measuring
error. In summary, the double color 水位计took the measuring
appliance opens when the boiler, stops monitors when steam drum water
level and normal operation regularly proofreads other patterns
水位? The differential pressure type 水位计uses in time
the stable parameter movement water level to instruct, and is suitable
to gives the water the automatic control; The electrode type
水位计comparison adaption boiler 变参?movement, the accuracy
is good, is to the differential pressure type 水位计survey
surveillance and the supplement. Therefore, generally
simultaneously uses these 3 kind of measuring appliances in the boiler
steam drum water level survey.
In 3 practical applications matters needing attention
The boiler steam drum water level decided stores under
the water volume and the water surface steam bubble volume in the
steam drum, causes in the steam drum to store under the water volume
and the water surface the steam bubble volume change factor are very
many, like the boiler steam load, gives the water current capacity and
the chamber hot load and so on. In is actual, if when the steam
current capacity increases (load increase), although the boiler is
smaller than the transpiration rate to the water volume, but the water
level not only does not drop, instead rapidly rises; Otherwise,
when shoulders reduces, the water level instead first drops, this is
"the false water level" the phenomenon. The reason is when the
load increases (reduction), under the water surface the steam bubble
volume gain (reduction) very quick creates. But the double color
水位? the electrode type 水位? the differential pressure
type 水位计cannot overcome "the false water level" influence.
Therefore monitors time the steam drum water level instruction
in the boiler movement, must simultaneously strictly monitor parameter
the and so on steam current capacity, for water volume change,
promptly grasps the steam drum water level the actual condition,
guarantees the boiler the stable safe operation.
4 my factories application situation
My factory 2nd kiln tail afterheat electricity
generation project has CPC to make up burns the stove and SP afterheat
stove each 1. When design the CPC stove uses the double color
水位? the single color 水位计and the differential pressure
type 水位? the SP stove uses the double color 水位计and the
differential pressure type 水位? The initial period tries
transports when the boiler movement operating mode to change in a big
way, as well as the SP stove and CPC stove frequent Xie Qi, and the
steam, enable the water level to undulate in a big way, during
appeared several time has lacked Shui Heman the water the significant
accident. Therefore in the CPC stove, the SP stove has
installed set of electrodes types 水位? When movement,
gives the water using the differential pressure type
水位计automatic investment, uses the double color 水位?closed
circuit TV surveillance) and the electrode type 水位计observes the
verification water level, and two between mutually verifies, when
appears exceptionally relieves automatically changes over to the water
manually. After period of time movements, proved this way effect
is extremely good. |
