Due to the long-term working conditions of high temperature, high pressure and high speed, the lubrication system of the large unit leads to the acceleration of oil oxidation speed, the increase of paint film index and the increase of gum content.
Soft impurities accumulate in the large unit system, affecting the accuracy of the speed control system and the normal operation of the unit, which is easy to lead to unit fluctuations or even unplanned shutdowns, and the paint film gelatinous matter deposited on the surface of the bearing will also cause the temperature of the bearing to rise, and the adhesion of the paint film and solid particles will also aggravate the wear of the equipment.
1. Project overview
CNOOC (China)** Tianjin Branch's BZ25-1 S Oilfield (Central Bohai Sea) Floating Production, Storage and Offloading Unit (FPSO) is equipped with four Titan130 dual-fuel gas turbine generator sets produced by Solar Corporation of the United States. The turbine generator set includes a gas turbine prime mover, a reduction gear unit, a generator, a control panel, a dashboard, a common base, a soundproof enclosure and various auxiliary systems. When the unit uses different fuels, its bearing capacity is also different. The thrust bearing of the unit adopts oblique pad bearing, the shaft diameter bearing adopts oblique gasket bearing, and the reducer adopts 3-stage planetary gear. The lubrication points of each bearing adopt the forced lubrication method of centralized oil supply. Four Titan130 dual-fuel gas turbine generator sets supply power to the entire oilfield, and there are four waste heat ** devices, which heat the hot medium oil through the high-temperature flue gas generated by the turbine, and the stable and safe operation of the four Titan130 dual-fuel gas turbine generator sets is crucial.
There is a problem with the unit
In April 2018, it was found that the bearing temperature of 4 units fluctuated, and the temperature of individual temperature points could not return to the original operating value after the temperature increased, and the turbine bearing (bearing) of one of the units reached a temperature of 108 and had an upward trend, and the remaining three units also showed an upward trend.
After some analysis, it was found that the paint film may have formed in the lubricating oil of the unit, and the paint film was eventually concentrated on the bearing, causing the bearing temperature to fluctuate and rise.
ResolvedBearingsTemperature rise problemmeasures
3.2.1. Change the lubricating oil pressure from 023MPa to 0245MPa, improve the efficiency of lubrication and heat exchange, and alleviate the trend of slow rise in bearing temperature.
3.2.2. Replace the aging oil cooler with low heat exchange efficiency with a new type of domestic direct drive cooler, and the oil supply temperature of the oil will be stable from 60 to about 50 for a long time.
3.2.3. The working principle of electrostatic adsorption technology - to remove the precipitated paint film
Electrostatic purification is the use of circular high-voltage electrostatic field action, so that the polluted particles in the oil respectively show positive and negative electricity, positive and negative particles under the action of the electric field force respectively to the negative and positive electrode direction, neutral particles are squeezed by the charged particle flow to move, and finally all the particles are adsorbed on the collector, completely remove the pollutants in the oil, through the flow of electrostatic oil particles, the oil tank, pipe wall and components attached to the sludge impurities, oxides are all washed out and brought out. Actively remove the sludge and gelatinous dirt adhered to the inner surface of the system, and play the role of cleaning the system.
Schematic diagram of electrostatic adsorption technology.
3.2.4. The working principle of ionic resin adsorption technology——Removal of dissolved paint film
Ion Exchange Resins - DICR removes soluble contaminants from turbine oils, ensuring a decrease in MPC levels, as turbines are mostly soluble during operation, and only when they reach saturation do these products form precipitation, and electrostatic equipment cannot remove these by-products in the dissolved state.
The combination of electrostatic adsorption and resin technology can not only effectively remove suspended paint film, but also remove dissolved paint film products.
Schematic diagram of the principle of ionic resin adsorption technology.
3.3 Remove the paint film effect
On December 14, 2019, the Weishengda environmental protection WVD model paint removal membrane oil purifier was installed and put into operation, and under the comprehensive measures of replacing the gas turbine lubricating oil cooler on August 20, 2020, the temperature of the turbine bearing (bearing) dropped from 108 to about 90. There is a significant improvement in the color of the oil. Through the analysis of laboratory tests and external testing data, the oil paint film tendency index was increased from 424 to 45. The pollution level is reduced from NAS 9 to 6, and the acid value index is reduced from 017 to 007。
Weishengda environmental protection paint removal membrane oil purifier.
The temperature trend of the bearing (bearing) after purification of the Weishengda environmental protection paint removal membrane oil purifier
The test and analysis results of the oil after being filtered by the Weishengda paint removal membrane oil purifier.
Comparison of the color of the oil before and after purification.
The economic benefits generated
Through the installation and operation of the Weishengda environmental protection WVD paint removal film oil purifier, the problem of rising temperature of gas turbine thrust bearings caused by paint film is effectively solved, and the major losses caused by the shutdown of the oil temperature problem of the unit are avoided, and even the loss of spare parts caused by bearing damage and rotating sealing parts is reduced, and the loss of maintenance bearings is reduced by more than 5 million yuan, and the coordination maintenance time cycle is long, and there is no backup unit at the production site, which has a serious impact on safe and stable production.
The unit needs to fill a total of 20 barrels of oil table, and the oil products fully meet the qualified indicators after high-precision filtration through the paint removal film, saving about 400,000 yuan in oil replacement costs.