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The Application of Combined Purification Technology on Varnish Prevention of Gas Turbine Lubricating Oils of Offshore Platform

AbstractThe forming mechanism and hazards of lubricating oil varnish were analyzed.The principle of varnish removal by the combination of charge adsorption filtration and exchange resin was introduced.The oil purifier based on this principle was applied on the varnish removal of gas turbine lubricating oil of offshore platform.The result shows that the varnish removal method and oil purifier equipment of charge adsorption filtration and exchange resin can recover the unqualified lubricating oil tested by MPC to the qualified range,can improve and eliminate the instability of lubricating oil system caused by varnish.The method and the equipment have good effect on improving the cleanliness of the oil and removing the fine pollutants.

Keywordsgas turbine;lubricating oil varnish;MPC test;charge adsorption filtration;exchange resin

Gas turbine is one of the core equipment of offshore platform. It is used as power generation equipment on offshore platform to ensure the stable and long cycle operation of gas turbine for ensuring the normal production of offshore platform. The gas turbine is in the condition of high temperature, high pressure and high speed during operation, and the varnish is easy to be generated in this environment. At the same time, with the improvement of the basic oil quality in lubricating oil, the ability of lubricating oil dissolving varnish deteriorates, which also intensifies the rapid formation of varnish. The formation of varnish causes the accumulation of varnish, great harm to the equipment, it will cause the decrease of clearance, increased wear, valve core adhesion equipment operation is unstable and even failure; the varnish deposited on the shaft, cooler and other components cause the temperature fluctuation of the shaft cooler heat exchange rate, oil oxidation acceleration: the varnish will attach to solid particles, block the filter element and throttle hole, resulting in equipment wear and poor equipment lubrication, domestic and foreign gas turbine abnormal paint failure shutdown occurs. In this paper, the author introduces the abnormal problems such as the tendency detection of Huizhou 32-2 platform Solar gas turbine generator set, discusses the application of the varnish removal unit  in the platform unit, and provides some reference for equipment maintenance personnel in related industries in the control of equipment lubricating oil varnish.

1 Formation mechanism and hazard of lubricating oil varnish

1.1 Analysis of lubricating oil film

varnish is a polymer, is the oxidation of oil objects, color from light brown, brown to tan, its generation of the main reason there are three aspects.

(1) Oxidative and degradation of oil products: oil products are in use in the course. High temperatures, water, metals, and air all accelerate oxidation, to generate carboxylic acid, ester, alcohol and other oxidation products, and further condensation form Into polymer: in addition, the amine antioxidant in oil is also easier to produce varnish.

(2) Local surface hot spots and microcom bustion cause the base oil or the rapid thermal degradation of additives to form varnish, high temperature or high strength friction Part of the metal surface at a higher temperature (common such as bearing bush), resulting in The temperature of the fluid contacting the area is very high, causing the fluid Rapid thermal degradation to produce varnish, and easily adhere to these components Formation of accumulation; lubricating oil in the case of sharp compression is also easy to produce micro Combustion phenomenon, to generate a very small size of the insoluble material, attached to the metal surface form a varnish, compared to the first generation of oxidation degradation, the second generation of paint The membrane speed will be much faster.

(3) The spark discharge will also form the varnish, especially when the oil passes through some sophisticated filter element to generate static current, the spark discharge phenomenon forms the varnish accumulation easily.

1.2 Hazard of lubricating oil varnish

Varnish accumulation on the friction side surface will reduce the oil film gap, heat dissipation change Poor, the lubricating oil fluidity deterioration, causing the friction auxiliary surface temperature to significantly rise High, severe damage to contact surface; gas turbine is always in open and stop the working state, the change of oil temperature is more likely to cause the shape of the varnish , the formed varnish can easily adhere to sophisticated components, such as hydraulic servo valve, resulting in valve blockage, valve core bond card dead, control failure and even equipment jump; varnish also causes cooler cooling effect is poor, purifier element blockage, poor lubrication aggravate wear and accelerated oil product oxidation and other consequences.

2  Varnish tendency index detection standards

At present, the method of measuring oil varnish tendency index is ASTM D7843 ” purifier membrane photometric analysis (MPC) detection in use Test method for color-insoluble material in steam turbine oil. The results are reported as paint Membrane tendency index AE. The principle of this method is using a vacuum filtration system Remove the sludge and gelatin from the oil product and deposit it in a clean purifier membrane On the plate (purifier membrane aperture 0.45 p, m), use the purifier after the purifier plate is dried Film chromaticity tester to test its MPC (AE) values. The purifier membrane was deposited The more things you get. The darker the color, the greater the varnish tendency index. When repeated

The continuous increase of MPC (AE) value should cause the equipment manager staff or maintenance personnel pay attention to it.

3. Application of the varnish removal oil purifier

3.1 Current status of lubricating oil before using varnish removal oil purifier

Huizhou 32-2 platform gas turbine generator set is a Solar T60 unit,

See Table 1 for the specific index parameters of lubricating oil before using the varnish purifier.

Table 1 The testing data of turbine oil before filtration

Project

Pre-purification data

 Reference value

tank model / capacity

The capacity of vortex 46 # oil / each unit is about 1800L

/

Motor viscosity of 40℃       V / (mm² s- ¹

45.37

41.4-50.6

Acid value (in KOH)  w/(mg·g-¹)

0.18

≤0.35

Moisture   c/(mg·L-¹)

46

≤100

 cleanliness ISO

23/21/11

≤–/16/13

varnish propensity index / MPC

31.5

≤20

The conclusion of the third-party testing agency is as follows: high varnish tendency index value table bright oil contains a large number of polar small molecule insoluble material, easy to adhere to the metal forms a varnish on surface, the varnish will cause the friction secondary temperature to rise and cause the equipment failure, extremely high particle content can affect the stability and the system service life of the related part, the oil can be continued to use, but required high filtration performance. Use a varnish removal facility to remove polarity from the oil solubility, it is recommended to shorten the sampling period and pay attention to cleanliness and MPC value and index monitoring results. Through the observation at the equipment site, the lubricating oil control pressure instability occurs in the operation, which seriously affects the reliability of the prepared lubricating oil system and liquid control components.

3.2 Principle and application of varnish removal unit

In view of the problem of varnish in lubricating oil, some enterprises adopted oil change measures, but the effect is not ideal and not environmental protection. To ensure that the generator set Reliability, decided to arrange for the unit varnish removal and filtration work.

The technical principles of several representative varnish oil purifiers are performed in Table 2

comparative analysis.

The comprehensive comparative analysis determines the charge adsorption + exchange tree

Lipid technology to remove the varnish from the oil. Through the actual test, I selected one

A WVD a clean varnish oil purifier, the oil purifier collection charge adsorption Purification technology and exchange resin adsorption technology in one, it is through the exchange tree

The varnish products are stripped and dissolved by charge adsorption technology

Remove the suspended varnish precipitated from the oil and the components that have been attached film.

Table 2 The contrast of different varnish prevention technologies

Varnish form

Exchange resin technology

Charge adsorption technology

Charge adsorption + exchange resin technology

Dissolved varnish in the oil solution

Removal by resin adsorption

Can’t remove

Removal by resin adsorption

Suspended varnish in oil

Removal by the resin reverse dissolution technique

Removal by charge adsorption filtration

Removal by combining charge adsorption filtration and resin reverse dissolution technology

varnish attached to the bearing bush and components

Removal by the resin reverse dissolution technique

The attached varnish can be actively removed by charged particles

The attached varnish is removed by combining charged particles and resin reverse dissolution technology

Comprehensive evaluation

Relying on the resin to remove the soluble varnish, and then removing the dissolved varnish and the components of the varnish through the long-term reverse dissolution principle of oil, the efficiency is low, and the resin consumables in the later period are heavy

Can only remove the suspended varnish in the oil and the varnish attached to the components, for the effect of the dissolved varnish is not ideal

Charge adsorption filtration technology combined with resin adsorption technology can not only quickly remove the dissolved varnish, but also can quickly remove the oil suspended varnish and components of the attached varnish, high efficiency, low late tree purpose wool material

3.2.1 Charge adsorption technology and working principle

Charge adsorption technology mainly uses the high voltage generator to produce high voltage static electricity Field, make the pollution particles in the oil are polarized and show positive and negative electricity respectively, Positive and negative electric particles are respectively oriented under the action of ultra-high voltage electric field The negative and positive electrodes swim, and the neutral particles are squeezed by the flow of charged particles shift. Finally, all the particles are adsorbed and attached to the collector, And through the part of the charged oil particles that have not had time to absorb the flow, will Mlay impurities, varnish and oxidation attached to the oil tank, pipe wall and components

All the objects wash out the adsorption band (see Figure 1). This technique can be effective in clearing The suspended varnish and the varnish attached to the components, for lifting

High cleanliness also has a better effect.

Offshore Platform2The principle of charge adsorption technology

3.2.2 Balanced charge purification technology

Balanced charge purification technology (Balanced Charge purification) method is to divide the fluid carrying small particles into two branches. Branch The road is equipped with high voltage electrodes to load the positive charge and small particles respectively Negative charge: then weight the two fluids with opposite charge particles

New hybrid aggregation. Positive and negative charges attract each other and gather together to form a large ruler 10 inch particles; end with a mechanical or centrifugal purifier An inch of increased particulate matter.

3.2.3 Exchange resin adsorption technology

It is impossible for the dissolved varnish products to rely on the charge adsorption technology

scavenging. The specially prepared resin material is the dissolved varnish product (Also called lacquer film embryo) give purifier medium high affinity, using resin The rich basic groups on the adsorption material can adsorb all kinds of degradation production very well thing. Thus has a high removal rate of the varnish products. The resin adsorption material Good material stability, high temperature resistance, the use will not have degradation products and fall off Things enter the oil. In addition, the use of resin reverse dissolution technology (rely on the tree After the lipid removes the dissolved film in the oil, the suspended film in the oil and attached With the varnish on the components will reverse dissolve back into the oil into a dissolved varnish, Then removed by resin adsorption), for the oil in the suspension state varnish and attached In the components of the varnish also has a certain removal effect.

3.2.4 Specific application effect of removing varnish oil purifier

Through the WVD a clear varnish oil purifier at the 32-2 platform Solar The T60 unit underwent online cycle purification for about 10 days. To the purified oil solution Sampling test data are shown in Table 3.

Table 3 The testing data of turbine oil after filtration

Project

Pre-purification data

 Reference value

tank model / capacity

The capacity of vortex 46 # oil / each unit is about 1800L

/

Motor viscosity of 40℃       V / (mm² s- ¹

45.43

41.4-50.6

Acid value (in KOH)  w/(mg·g-¹)

0.12

≤0.35

Moisture   c/(mg·L-¹)

55

≤100

 cleanliness ISO

15/13/9

≤–/16/13

MPC

4.4

≤20

Found through the third party oil testing agency.lube After purification, the tendency and cleanliness index of the film before purification are obvious Improvement, the acid value also decreased significantly; although the water is slightly increased, but Considering that the detection error and other factors are still within the qualified range, so it is not considered as a reference Test basis; all other indicators are normal, and the test conclusion is qualified. At the same time clear The lubricating oil control pressure is unstable during the operation of the varnish purifier Significant improvement, and the effect is obvious.

4  Conclusion

Method for the combination of charge adsorption and exchange resin device can significantly improve the tendency of gas turbine lubricating oil standard and pollution degree indicators. Install the Solar T60 unit in the 32-2 platform after using varnish removal oil purifier with WVD series. The unit lubricating oil varnish propensity indicators and cleanliness were improved and returned to the eligible range, achieved the desired effect, prevent the formation of varnish,some other physical and chemical The index has also improved, most notably the lubricating oil control pressure in the unit the phenomenon of force instability has also been eliminated, ensuring the stable operation of the unit. In addition, the varnish removal unit runs stably in the harsh environment, the effect is obvious, the late consumables cost is low, has a good applicability.

Offshore Platform


Post time: Mar-15-2023
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