Hello,
SEE MY REPLY IN CAPS
- Do we need to put any water inside the pipelines before we do steam
blowing?
IDEA OF STEAM BLOWING IS TO ENSURE THE CLEAN STEAM TO EQUIPMENT LIKE STEAM
TURBINES, WHICH ARE SENSITIVE TO FOREIGN PARTICLES IN THE STEAM. HOW ONE
WILL ENSURE THAT...DEPENDS ON INDEPENDENT CHOICE. SINCE THE STEAM IS MUCH
COSTLIER THAN WATER, NORMAL TENDENCY IS FLUSH THE PIPELINE WITH WATER
THOROUGHLY, SO THAT ALL MAJOR DIRT, FOREIGN BODIES (NOT UNCOMMON TO SEE DEAD
BIRDS, TOOLS ETC) AND WELDING DEBRIS. MOREOVER AFTER COMPLETION OF THE
FABRICATION PROCESS, PIPELINE HAS TO BE HYDROTESTED. ONCE THE HYDROTEST IS
COMPLETED, FLUSHING CAN BE CARRIED OUT. THEN DRAIN OUT THE LINE AND ADMIT
THE STEAM FOR STEAM BLOWING.
- How do we calculate the Disturbance Factor, Cleaning force ratio and
Maximum continuous rating for the steam blowing?
EVEN THOUGH I AM INVOLVED IN STEAM BLOWING OF SOME DRIVE TURBINE LINES, I
DID NOT COME ACROSS THESE TERMS. THESE SEEM TO BE MORE THEORETICAL THAN
REALITY. BASIC IDEA IS TO MAINTAIN THE STEAM VELOCITY AND CONDITIONS SAME
AS THAT OF DURING NORMAL OPERATION. BUT IT IS ANYBODY'S GUESS HOW ONE CAN
MAINTAIN THE DIFF.PRESSURE BETWEEN STEAM SOURCE AND ATMOSPHERE (SINCE THE
EQUIPMENT WHICH IS EXPECTED TO TAKE THE DIFF.PRESSURE IS NOT ON LINE). IN
VIEW OF THIS STEAM DRUM PRESSURE WILL BE MAINTAINED AT AS MAXIMUM AS
POSSIBLE WITH THAT OF NORMAL RUNNING CONDITIONS. STEAM WILL BE ADMITTED INTO
BLOWING LINE AT SUITABLE FLOW RATE. IN CASE SOME OF THE OTHER
UNITS/EQUIPMENT ARE USING THE STEAM FROM SAME SOURCE, PROPER BALANCE HAS TO
BE ACHIEVED SO THAT OTHER EQUIPMENT ARE NOT DOWN.
- Any special instrumentation needed for the process?
NOT REALLY...EXCEPT FOR THE ARRANGEMENT FOR VENTING THE STEAM TO ATMOSPHERE
AT SUITABLE ELEVATION AND ARRANGEMENT TO INSERT THE TARGET PLATE JUST BEFORE
THE VENT OUT CONNECTION. SINCE IT CREATES TREMENDOUS NOISE POLLUTION,
SILENCER MAY BE OPTED. ONE HAS TO ARRANGE THE TARGET PLATES (NOTHING BUT A
HIGHLY POLISHED CLEAN METAL SURFACE) IN SUFFICIENT NUMBER....MAY BE 10.
TARGET PLATES NEED NOT BE INSERTED FOR INITIAL FEW BLOWS AND IT CAN BE
STARTED AFTER 6 OR 7 BLOWS. PERMISSIBLE CLEANLINESS FOR TURBINE VENDORS
IS...DOTS/SPOTS ON TARGET PLATE SHOULD NOT BE MORE THAN TWO.
- How long it will take for the process to finished?
IT IS AGAIN A GUESS. IT DEPENDS HOW U STARTED THE PROCESS AND FOLLOWED. I
HEARD OF THE CASES WHERE THE BLOWING COMPLETED WITHIN LESS THAN A WEEK. ALSO
SEEN THE CASES WHICH LASTED FOR MORE THAN 4 WEEKS. IT ALL DEPENDS ON LENGTH
OF NEW PIPE, NO. OF BLOWS GIVEN, DURATION OF EACH BLOW, INTERVAL BETWEEN THE
BLOWS, STEAM FLOW RATE/VELOCITY ETC. BASIC IDEA IS HEAT THE LINE DURING
BLOWING AND ALLOW THE LINE TO COOLDOWN TO AMBIENT TEMPERATURE. THIS HEATING
AND COOLING PROCESS DETACHES THE SCALES FROM PIPE LINE AND THOSE WILL BE
BLOWN OUT IN THE NEXT BLOW. ONE OF OUR GROUP MEMBER IS REFERRING TO
PORTABLE STEAM GENERATION UNIT FOR BLOWING. BUT I NEVER USED THAT, SINCE
GENERATING THE HIGH PRESSURE STEAM AND REQUIRED FLOW RATE WAS A LIMITATION
IN OUR CASES.
- Anyone have any write-up procedure on steam blowing?
I WAS HAVING WITH ME..NOT AT PRESENT. YOU CAN FIND IT IN ANY STEAM TURBINE
INSTALLATION MANUAL. OTHERWISE CAN GET IT FROM STEAM TURBINE MANUFACTURERS
OR FROM YOUR ROTATING MACHINERY GROUP.
Thanks for your help
U ARE WELCOME. HOPE IT EXPLAINS THE PROCESS TO U ATLEAST UPTO SOME EXTENT.
IF ANY DOUBTS, LET ME KNOW. PLEASE NOTE THAT ABOVE EXPLANATION IS
CONSIDERING THE STEAM FOR STEAM TURBINES/DRIVERS. IF IT IS FOR PROCESS
USAGE..I HAVE NO EXPERIENCE.
HARI
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Received on Sat Oct 06 01:16:00 2001