US 11,988,657 B2
Method for determining degree of sludge generation in oil
Akihiko Yano, Tokyo (JP); and Akihiro Nozaki, Tokyo (JP)
Assigned to MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
Appl. No. 17/271,011
Filed by MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
PCT Filed Sep. 19, 2019, PCT No. PCT/JP2019/036688
§ 371(c)(1), (2) Date Feb. 24, 2021,
PCT Pub. No. WO2020/059776, PCT Pub. Date Mar. 26, 2020.
Claims priority of application No. 2018-175297 (JP), filed on Sep. 19, 2018.
Prior Publication US 2021/0325363 A1, Oct. 21, 2021
Int. Cl. G01N 33/28 (2006.01); G01N 33/30 (2006.01)
CPC G01N 33/2888 (2013.01) [G01N 33/30 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method for determining a degree of sludge generation in oil, the method comprising:
a step of generating degraded oil, which is obtained from oxidation of oil, by immersing and rotating a pressurized vessel, in which oil and a copper catalyst are put and which is pressurized by substitution of gas with oxygen or injection of oxygen or air until oxygen partial pressure reaches a maximum pressure higher than a value thereof under an atmospheric pressure, in a thermostatic bath having a predetermined temperature;
a step of measuring a Rotating Pressure Vessel Oxidation Test (RPVOT) residual ratio, which is an index value representing a degree of degradation of the degraded oil caused by oxidation, of a part of the degraded oil by an RPVOT test and measuring a weight of sludge, which is filtration residue, thereof; and
a step of determining ease of generation of the sludge caused by the degradation of the oil from a relationship between the measured RPVOT residual ratio and the measured weight of the sludge,
wherein:
a first period is specified before the step of generating the degraded oil, pressure in the pressurized vessel being reduced to a predetermined pressure from the maximum pressure such that an estimated value of the RPVOT residual ratio is substantially 0% and excludes 0% in the first period;
the step of generating the degraded oil is executed for a second period shorter than the first period; and
the second period is adjusted according to a linear relationship between the estimated value of the RPVOT residual ratio and the measured RPVOT residual ratio.