SA Ras Al Khair O&M Team Solved the LP Steam Contamination Problem of ST50 Successfully
It is easy to talk about but difficult to implement the originality and being professional. They come from consciousness and should be implemented in details and be ended in their value.
In the past two years, the LP steam contamination problem of ST50 has always been a big problem to the technical staffs of SA Ras Al Khair Project.
In October of 2017, the O&M project set up a specific team to solve the problem with the originality spirit and iron army style, finally found the pollution source and solved the problem in Mid-November, and showed the originality spirit with its jobs.
On November 3rd, 2017, the company received a piece of good news from SA Ras Al Khair Project that the condensed water’ conductivity of ST50 exhaust steam was 0.07us/cm, which was superior to the standard and means that the LP steam contamination problem of ST50 is solved by our O&M team.
In the commissioning period of ST50 in the latter half of 2015, the project found that there was contamination in LP exhaust steam of ST50. The project then checked a lot from chemical sampling analysis, instrument and meter, washing the pipes to disassembling the pipes, but found nothing.
Doosan was forced to use the measure of continuous exhaust to insure the water and steam qualities, but that will cause losing desalted water and heat in quantity. The owner also sent letter to urge them to solve this problem.
The project has always been investigating and finding the pollution source.
In October, the O&M project set up a specific team led by Mr. Wu Haifeng, Manager of Operation Department, and Mr. Cheng Jiyu, Manager of Maintenance Department, to solve the problem.
The Operation Department paid high attention to the job, set up the main team including Mr. Sun Fei, Mr. Wang Jinwei and Mr. Huang Bingfang and organized the operators and chemical staffs to solve the problem.
The main team led by Mr. Ma Qingsheng, Project Deputy Manager, worked hard and cooperated closely to check the system. They searched similar cases, discussed and checked, and worked overtime for just one doubtful point.
The main team also came to Doosan for checking and testing, but Doosan’s staffs were so impatient. The team then came to there with beverages in order to finish the works.
By gathering data, analysing chemical samples and combining with the Doosan’s operation test, the main team changed the way of thinking and made the preliminary conclusion:
The abnormal condensed water index is not caused by solid impurities. It is because that the gas influenced the conductivity of hydrion, which means that the air entered into the steam system.
The conclusion shocked everyone. It seems impossible, because the steam system is a 1.8bar positive pressure system. But the conclusion still showed the way to the following works.
The main team searched relative design instruction, commissioning materials and system drawings and checked the systems one by one, finally insured the key checking point on metering and service compressed air system.
After comparing with other units, the team found that the temperature of the location of the ST50’s exhaust butterfly valve sealing system to the main pipe was lower around 10℃ than other units, then the pollution source was insured: it is the butterfly valve sealing valve leakage.
After that, the team organized personnel to do the relative test. The MSF75/76’s conductivity of Doosan was decreased from 0.134us/cm and 0.105us/cm to 0.09 and 0.07us/cm by insulating the related service air systems while increased to 0.24us/cm by using the systems, and the exhaust valve was forced to open. The pollution source was finally found!
The operation staffs and maintenance staffs cooperated with each other and finished the technical reform jobs for the exhaust butterfly sealing system of ST20 to ST60 on November 16th. The steam quality problem of Doosan was solved successfully.
Solving the problem ended the abnormal operation mode of Doosan maintained for 2 years. It will save the steam, increase the unit efficiency and decrease the chemical water make-up rate of the power plant. The O&M team showed the originality spirit and iron army style with its excellent jobs, won appreciation from both the owner and Doosan and also built firm foundation for implementing the O&M contract.