An introduction to the blending process of lubricating oil

1. SEMINAR - 1
AN INTRODUCTION TO THE BLENDING PROCESS OF LUBRICATING OIL
SAPTAHRISHI SAHA
ROLL- 001910301105
BCHE UG 4 A2 SECTION

2. LUBRICANTS
DEFINATION: Lubricant is a substance which is used to reduce friction and wear of the surfaces in a contact of
the bodies in relative motion.Depending on its nature,lubricants are also used to eliminate heat and wear debris,
transmit power,protect,seal.A lubricant may be liquid(oil,water,etc),solid(graphite,graphene),gaseous(air) or even
semisolid(grease) forms.The liquid lubricants can be classified based on the base oil to synthetic/semi-
synthetic,mineral or environmentally acceptable(biodegradeable)oils.Most of the lubricants contains addetives(5-
30%) to improve their performance.
LUBRICATION MECHANISM: All the surfaces in nature are rough,at least microscopically (or even at atomic
level).When two rough surfaces slide against each other (or roll) the asperities of the surfaces come close to each
other and interlock,adhere and generate friction. The goal of any lubrication approach is to separate the rubbing
surface by a lubricant layer, which prevents (or at least minimize) direct contact of the bodies as shown in the
figure below

3. TYPES OF LUBRICANTS
Lubricants are of two types:
1.Mineral base
2.Synthetic base
MINERAL BASE LUBRICANT
This is a complex base of paraffinic, olefinic,aromatic and napthenic hydrocarbons of molecular structure C14 to
C40 and above along with asphaltenes, resins, wax,Nitrogen, Phosphorous and Sulpher molecule. Paraffinic base
oils are preferentially used to formulate most of the World’s automative and industrial lubricants including
engine oils, transmission oil,gear oil due to their high oxidation stability,high viscosity index and low volatility.
Napthenic base oils have lower pour point, low viscosity index and better solvency characteristics compared to
paraffinic base oil.They are most preferably used to formulate refrigeration oil,shock absorber oil etc.
SYNTHETIC BASE LUBRICANT
Synthetic base oils are superior quality base stock over mineral base stock in lubricant technology.These are
highly stable ,durable,biodegradeable and costlier base stock. Most widely used synthetic base stocks are as
follows:
1. Organic esters
2. Phosphate esters
3. Poly alkylene glycols
4. Alkyl benzenes
5. Synthetic hydrocarbons
6.Poly hydrocarbons etc.

4. FUNCTIONS OF LUBRICANTS
• Lubricants form a thin layer between moving parts thus keeping them apart. This helps to reduce friction,surface
fatigue, heat generation, operating noise and vibrations.
• Liquid and gaseous lubricants can transfer heat.Liquid lubricants are more effective as they have high specific
heat capacity.Circulation of lubricants helps temperature regulation.
• Lubricants reduce surface-to-surface friction.The lubricant-to-surface friction is much less than that and it
contains additives known as friction modifiers which helps in reducing friction.
• The circulation of lubricants helps to carry away the internally generated debris and external contaminants that
gets introduced into the system.
• It prevents wear and tear by keeping the moving parts apart.
• Lubricants are formulated with additives that forms chemical bonds with surfaces or exclude moisture to prevent
corossion and rust.
• It occupies the clearence between moving parts through capillary force thus sealing the clearence. This effect is
used to seal piston and shafts.
• It is also used to transmit power by acting as hydraulic fluid.

5. BASE OIL:
This is a complex mixture of paraffinic, olefinic, aromatic and naphthenic hydrocarbons of molecular structure of
C14 to C40 and above along with asphaltenes, resins, wax,Nitrogen, Phosphorous and Sulpher molecule.
In 1993, the API categorized base oils into five main groups.This breakdown is based on the refining method and the
base oil properties in terms of viscosity index, saturates and sulphur content.
Group 1 Saturates <90% sulphur > 0.03% viscosity index: 80-120
Group 2 Saturates >=90% sulphur < 0.03% viscosity index:80-120
Group 3 Saturates >90% sulphur < 0.03% viscosity index above 120
Group 4 Polyalphaolefins
Group 5 All other not included above, such as polysters,polyalkyene glycols etc.
ADDITIVES:
Additives are used to boost performance of lubricants and impart performance characteristics. It is vital for
prolonged use of motor oil in modern internal combustion engines, gear boxes, automatic transmissions and
bearings. Some of the additives used and their functions are given below:
Detergents: Detergents form a protective layer on the surfaces to prevent deposition of sludge and varnish.
Dispersants:
• Suspend harmful products (i.e. dirt, water, fuel , process material,and lube degradation products such
as sludge, varnish , oxidation products) within the lubricant.
• A large hydrocarbon tail and a polar group head.Tail section serves as solubleizer in the base oil, while
polar group attracts particulate contaminants in the lubricant.

6. Desired properties of lubricants
• Adequate film strength
• Chemical stability
• Adequate lubricity(Adhesive to surfaces)
• Purity(free from contaminants)
• Non corrosive
• Good sealing properties
• High VI
• Minimum volatility

7. Anti-wear additives
• Prevent metal to metal contact by making a protective layer on the metal surface by chemical decomposition
and absorption.
• Molybdenum disulphide and graphite additives are special type of antiwear additives known as anti seize agents.
• This is used only for low and medium stress application for high stress application we use EP addetives or
extreme pressure addetives because they have high bond energy
Anti-foaming agents
• Formation of air bubbles in the lubricants.
• Lubricant foams due to agitation and aeration that occurs during operation.
• Detergent and dispersant additives tends to promote foam formation.
• Interfare with flow rate and heat transfer.
• Foaming increases oxidation.
• The additives lower the surface tension between the air and liquid to the pontwherebubbles collapse.
• Usually long chain silicon polymers are used in small quantities 0.05 to 0.5% by weight polymethacrylates.
Anti-oxidant additive(Oxidation inhibitor)
• Oxidation due to high temp and pressure.Products of oxidation.
• Gummydeposits on surface.Corrode cadmium , copper & lead alloys.
• Power loss due to increased viscous drag & difficulties in pumping.

8. • Corossion inhibitors: Used for non-ferrous metals(copper, aluminium, tin, cadmium etc. used in bearings, seals).
Protect surfaces against any corrosive agents(sulphur, phosphorus, chlorine, and oxidation products) present in
oil.
• Rust inhibitors: Needed for ferrous metals. Oxygen dissolved in oil & water.
• Pour point depressants:Lowest temp at which lubricant will flow.
• Pour point depressants: Reduce the pour point and therefore are required when operating at lower
temperatures.
• Viscosity index improvers: they make oil viscosity higher at elevated temperatures.
Types of Lubricants
• Automative oils: Diesel Engine oils, Electric Vehicle,Agriculture oils,Gear and Transmission oils etc
• Industrial Oils: Compressor oils, Cylinder Oils, Hydraulic Oils, Refrigeration compressor oils,spindle oils,Turbine
oils
• Aviation: Gas turbine engine oils, Piston engine oils

9. Importance of lubricant Additives
Surf 1 Surf 2 Lubricant K1(wear
const.)
52100 steel 52100 steel None 1.0 ∗ 10−3
52100 steel 52100 steel Paraffinic oil 3.2 ∗ 10−7
52100 steel 52100 steel Paraffinic oil+
additive
3.3 ∗ 10−8
52100 steel 52100 steel Engine oil 2.0 ∗ 10−10

10. EQUIPMENTS OF LUBE OIL BLENDING PLANT:
STORAGE TANK: Storage tanks are containers that hold liquid, compressed gases or mediums used for short –or long
term storage of heat or cold. They are made up of mild steel and stainless steel. In lube blending plant the basee
oils, additives , products and water are stored in the storage tanks.
BLENDING KETTLE:
It is used for blending or mixing oil.Various capacities are fabricated according to the need of the client.Carbon
steel is used for shell and dish material, all legs are of H-beam and with outside surface primer finish.

11. PUMPS:
Different pumps are needed in Lube oil blending plant for transferring raw materials,re-circulation in Lube oil
blenders , circulating thermic fluid etc.Mainly gear pumps and centrifugal pumps are used.
BOILER
Steam is required to maintain the temperature of 50-60°C during blending of lube. So the plant has a 5MT
capacity of fire tube boiler to make steam. It is a 3 pass reverse flue smoke tube boiler of RevoTherm make. LDO is
used as fuel.
A boiler or a steam generator is a device used to create steam by applying heat energy to water. The steam
generated is required to heat the base oil additive mixture while blending process. The boiler used in this plant is
an Oil-Fire smoke tube packaged boiler. It is a 3 pass boiler i.e. the flue gas circulates the boiler 3 times with the
help of pipes before it gets out of it, so that maximum heating can take place. Forced circulation takes place with
the help of a fan. Water used is first softened & then heated. It has 2 operation mode: high fire (more heating for
more production of steam) & low fire. Water level should always remain about 70%. The safety devices used are
water level indicator controlling the feed pump, fusible plug, safety valve & water gauge.

12. FILTER
Fine filters are required to eliminate solid impurities from manufactured lube oils.Stainless Steel mesh screen filters
are used.
The lubricant is filtered through a 40 micron filter then stored in storage tank if it is frequently made else it is
stored in containers of different capacity and dispatched. Some lubricants are also filtered through NAS (National
Aerospace Standard) filter for very fine particle filtering.For NAS filtration the lube is past through 5 micron, 4
micron, 2 micron respectively. It converts number of particles present in a specified size range into different NAS
class.

13. Lube blending process
Introduction
Blending refers to the process of mixing. It is a physical batch process.
In lube blending base oil is mixed with additives(in required amount as per the lube to be processed) according to
the formulation made in a blending kettle for 2-3 hours by passing compressed dry air through the mixture agitating
it in the process and in presence of continuous heat with the help of superheated steam. The base oil and the
additives from the tank is filtered before they are filled in the blending kettle by a 100 micron filter. The additives
from the barrel are poured in a place called ‘sump’ below the blending kettle and then it is pumped to the blending
kettle from there. After blending, a sample of the lubricant made is checked by the Quality Control Lab on certain
parameters. If the lubricant gets passed for all the test then the lubricant is sent for storage else the lubricant is
again blended with rectification.
The lubricant is either direct stored in the storage tank else it is stored and packed in barrels, drums and other
containers for direct dispatch after being filtered in a 40 micron filter. The lubricants which are frequently made
are stored in the product storage tank.

14. A flowchart of the process is given below:

15. Blending is carried out in kettles and the operations are manually controlled. The charging of inputs i.e base oils
and additives may be partly manual or automated. Measurements of the input can be on volume basis or on weight
basis(in case of the solid additives)
In this image a blending kettle is shown

16. Procedure
Base oil charging in kettle
After issue of Blending sheet by blending officer, the following procedures to be followed for base oil mixing in
kettle.
• Physically the emptyness of the blending kettle is to be checked.
• The bottom valve of the kettle is to be closed before starting of charging.
• The line should be made through for the base oil receipt in the kettle.
• Communication to pumpman by blender, the source of the base oil tank, quantity of base oil to be charged ( in
kl).Pump man makes the line connection between the kettle and the base oil tank.Close the tank valve on
immediate basis once the required quantity of base oil is charged in the blending kettle.
• The above procedure is repeated if more than 1 base oil is required for blending.
• For all emulsion/ water sensitive grades the base oil is suitably agitated.The base oil is agitated for 30-45 mins or
as required for getting homogeneous mixture. Kettle sample is checked periodecally till clear, homogeneous
mixture is formed.

17. Additive charging
After a homogeneous mixture is formed , additive charging shall be done as per the following procedure.
The emptiness and cleanliness of the sump is checked .
• The dropline valve of the blending kettle is opened.
• If available the steam line is opened for heating and mixing addetives.
• Additive barrel is charged into the sump. The quantity and number of barrels charged are recorded in batch
control register.
• The suction valve of the pump is opened for lifting base oil and additive mixture into the blending kettle.
• The barrel is rinsed using oil, so that entire quantity of the additive can be taken out from the barrel.
• The flow of the oil from kettle to the tank and flow of the mixture from sump to the kettle is regulated to avoid
any overflowing from the sump.
• It is ensured no additive base oil remains inside the sump once the additive charging is completed.
Blending process
The process of blending requires agitation and heating. For steam heating the following procedure is to be followed-
• Moisture from steam coil and condensate line is drained out.
• The steam valve is opened slowly and temperature is montored from the dial gauge/PLC
• The temp of the product should be maintained as per process manual
• The temperature of the system should be controled either by manual supervision or through system control.
• For agitation following process followed
• Continueous charging and agitation of the product of blending kettle by stirrer and air of the product in
blending kettle.
• Agitation to be done for adequate time depending on the size of the blend and type of additive charged.

18. QC checks required parameters of the final blend.
If the blend meets specifications, QC advices density of the product at 29.5°c to blending officer.
Once the product settles take dip and temperature of the product.
Transfer the product to settling tank.
In case the product is not cleared by QC following to be followed-
• Repeat sample is sent to the QC for further testing and assesing the parameter it is failing to.
• After charging extra base oil and for additive , product is agitated for another 45-60 min.
• Sample is sent to QC for clearence.
Quality Control Operation:
Sample testing is necessary as a part of quality control. Several types of samples are taken for testing purposes:
• Appearance : It is a visual examination of the product. This helps to check whether the product is clear, bright &
free from suspended particles, sediments. We get to know the purity of the product w.r.t. incomplete blending,
additives insolubility &product stability.

19. KINEMATIC VISCOSITY BATH:
• Identification of class of lubricant with respect to viscosity. Defined as the resistance to flow under gravity .
• Measured as : v = c * t ( where , c- calibration constant of capillary, centistokes/sec and t- measured time in sec)
to flow a fixed volume of liquid through Capillary under gravity.
• We check the viscosity in 100 degree c for moto lubricants and 40 degree c for other types
Significance:
• It’s a critical property which determines the suitability of application of lubricant to the user.
• Depending upon the load, film thickness and hence the viscosity the class of lubricants is chosen.
VISCOSITY INDEX
The viscosities of lubricating oils change rapidly with temperature. The rate of change of viscosity varies with the
type of oil. The rate of change of kinematic viscosity with temperature is indicated by the viscosity index. It is
found with the help of the viscosity at 2 different temperatures (mainly 40 &100∙C) from the V.I. chart.

20. TEST FOR POUR POINT:
The test sample is taken upto the specific mark in a pour point jar.
Depending upon the pour point the test jar is gradually transferred from 0 degree bath to - 51 degree bath.
Observation of flow should be started before 9 degree Celsius and in every 3 degree of interval.
The pour point should be reported by adding 3 degree with the temperature at which the flow of the sample
ceases.
CLEVELAND OPEN CUP APPARATUS: DETERMINATION OF FLASH AND FIRE POINT:
The cup is filled at any convenient temperature so that top of meniscus is exactly at filling line. The test flame is lit
and is adjusted to a diameter of 3.2mm to 4.8mm.Heat is initially applied. When sample temperature is apparently
56 degree below the anticipated flash point the heat is decreased so that the temperature rise for the last 28
degree Celsius is 5 to 6 degree per minute. For last 28 degree, the test flame is passed across the centre of cup at
right angles to diameter which passes through the thermometer. When a flash appears at any point on the oil
surface the temperature on the thermometer is recorded as the flash point.
To determine fire point the heating is continued so that sample temperature increases at the rate of 6 degree per
minute and the application of test flame is continued at 2 degree intervals until oil ignites and continues to burn for
at least 5 seconds.

21. Demulsification Test (D 1401) :
• Determines the ability of the petroleum products to separate from water.
• Products whose KV at the rate 40° C is 90 CST or below test temp is 54° C. KV above 90 CST at the rate 40° C test
temp is 82° C.
Significance:
• Required test for turbine and hydraulic grades which is mixed with water/ steam/condensate on service. So
water separability is prime requirement of lubricant, as emulsified oil causes lubrication failure.
COLD CRANKING SIMULATOR:
Many engine oils are non Newtonian at low temperature ,apparent viscosity varies with shear rate .It measures
apparent viscosity of engine oils at -5 degree Celsius to -30 degree Celsius at shear stress 50000 pa to 100000 pa .An
electric motor drives a rotor that is closely filled inside a stator.oil fills the space between rotor and stator. Test
temperature is measured near stator inner wall and maintained by regulated flow of refrigerated coolant through
the stator .The speed of rotor is calibrated as a function of viscosity. Test oil viscosity is determined from calibration
and measured rotor speed.

22. FOAMING TEST:
Foaming takes place at the upper surface of lubricant in system. Storage especially in high speed gearing, high
volume pumping and splash lubrication. Foaming is undesirable due to inadequate lubrication; cavitation’s and
overflows loss of lubricant which leads to mechanical failure.
190 ml of the sample is taken in a specified 1000 ml foaming cylinder fitted with diffuser stone.
The cylinder is immersed in constant temperature bath and the sample is allowed to attain the desired
temperature which is 84 degree Celsius.
Through the flow meter air is passed for 5 minutes into the sample at a rate of 94 +- 5 ml/min.
The volume of foam in ml after 5 mins of air blow is recoded and after 10 mins t the end of a blow.
The foam volume in ml is reported as tendency and stability.

23. THANK YOU