Hello ! power engineers today we discussed about the MOST WANTED TURBINE QUESTION ANSWER . these question answer is helpful for those who worked as a turbine operation engineer and who want to know more about the turbine operation . turbine is critical component of any power generation plant because its consist very critical component like thrust pad , blades , bearing etc. which takes extra care during start up of the turbine . these question answer help us the our readers know more about the turbine operation. lets discussed the question answer in detail way
Q. 1 What sort of reasons shall be take into account when start the turbine actuation, and how about the concerning points?
Ans. (1) The main reasons account for the turbine actuation failure including:
-The turbine movement part was locked up;
-Low vacuum or new steam pressure during the rotor actuation process;
-Error operation, necessary valves does not open (i.e., emergency sliding stop valve, constant stop valve or regulation steam valve, etc).
(2) Concerning point: control device’s location when start turbine, opening status of the constant close valve or regulation steam valve, the route of the oil movement device compared with the normal start up. Quick stop and reason analysis shall be taken if the rotor cannot rotate.
Q. 2 Are there any concerning points to be notified before turbine hot start?
Ans. (1) Efficient warm up so as to promote the steam temperature and reduce the turbine steel parts’ heat resistance;
(2) Lube oil temperature shall be no less than 35℃ so as to facilitate the lube the lube oil membrane shaping and thickening process;
(3) Do best to promote the condenser vacuum and reduce the steam temperature;
(4) Steam sending to the shaft seal shall be handled before water jet air-taker, and then vacuumize;
(5) Actuation until rated rotation speed, if normal as usual, no need pause and warm up,
Q. 3 Why is the steam supplied to the shaft seal prior to vacuum extraction when the turbine starting up at hot state?
Ans. Because the metal temperature of rotor and steam cylinder is very high during hot start-up, if extract vacuum first, cooled air will flow into the cylinder along the shaft seal. The cooled air, as we know, will naturally flowing to the bottom part of the cylinder resulted in the sudden cooling of the lower cylinder therefore making the temperature difference of upper and lower cylinder will increase and leading to the cylinder deformation and kinetic and static frictions. Those will make the turning gear abnormally put-in resulted in main shaft deformation, at the same time, hot impaction will brought by the cooled air to the main shaft, thereafter it is important to supply steam to the shaft seal before the vacuum extraction.
MOST WANTED TURBINE QUESTION ANSWER
Q. 4 Why shall the temperature of exhaust steam be maintained lower than 65℃ during the turbine normal running, but the maximum exhaust temperature be up to 120℃ during the time from start-up driving to no-load running.
Ans. Because the flow rate of steam during normal running is very large with the exhaust steam being saturated. The temperature of exhaust steam varies and increases as the exhaust pressure rises, bringing about the hot load increase at unit area of condenser and vacuum reduction. In addition, loosen and water leakage of the copper tube will also be taken into consideration, therefore, it is required to maintain the exhaust temperature within 65℃
The state of exhaust steam, due to the small flow rate and throttling of the regulating valve and blasting friction effect, is in the overheated state. However, the exhaust pressure and the hot load of condenser unit area are not very high with adjustable vacuum condition and no potential damage of the condenser copper expansion joint from the excessively heavy heat impaction. Therefore, the exhaust temperature shall be a little higher but not be allowed to excess 120℃ as the speed rise and no load running period normally.
Q. 5 What shall be paid attention to when the rotation speed excess the critical speed during the start-up?
Ans. (1) In order not to cause any malfunctions, normally, swiftly and smoothly run over the critical speed without adopting the method of pushing through the critical speed at a very fast speed. It is stipulated that the speed rise ratio after running over the critical speed is around 600r/min.
(2) Pay attention to the compare and contrast the vibration and speed to make sure the vibration style and inhibit any wrong judgement and analysis.
(3) The vibration sound shall be normal without any excessive vibration and bumping & friction noise, otherwise, it is urgent to trip the gate valve to shut down the unit and then check out the causes. Re-start-up shall be allowed when there is no more abnormal cases.
Q. 6 what is the ratio of steam consumption? What is the ratio of heat consumption?
Ans. The quantity of steam consumed by producing unit work refers to the ratio of steam consumption.
The quantity of heat consumed by producing unit work refers to the ratio of heat consumption.
Q. 7 what are the main indexes of the turbine heat economical efficiency?
Ans. They are: (1) Pressure of main steam.
(2) Temperature of main steam .
(3) Degree of condenser vacuum, difference between the inlet and outlet and condensate water super-cooling degree.
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