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PATTERSON Industries Canada  "The Process Equipment People" designs, engineers and manufactures the PATTERSON Double Motion Grease Kettles that are extensively used in the production of lubricating greases for the automobile, aircraft, railroad and industrial applications.

Laboratory and Grease Research Equipment

PATTERSON INDUSTRIES CANADA  manufactures 
and designs state of the art Grease Research Equipment.  Below is 
shown a PATTERSON Automated Grease Kettle  & Related Equipment – 
Grease Mill, Grease Filter, Grease Pump, Heating and Cooling System, 
Vacuum System and Controls 
and consisting of:                                                             

A)               6 kg (13.2 lb) Working Capacity PATTERSON GREASE
           SAPONIFICATION/FINISHING KETTLE complete with PATTERSON
           Double Motion Counter - Rotating Agitator Stirrer consisting of a
           Stationary Mounted 

			Drive Assembly and Grease Kettle Body that can be manually raised and lowered. A Flush Bottom Handwheel-operated Discharge/Sampling Valve is located on the Kettle bottom.
The PATTERSON  Autoclave-type Pressurized 6 kg (13.2 lb) Working             Capacity  GREASE REACTOR KETTLE comes complete with a             PATTERSON   Double Motion Counter - Rotating Agitator Stirrer             basically  consisting of a Stationary Mounted Drive Assembly and              Grease Kettle Body that can be manually raised  and lowered -              similar to a Drill Press Arrangement.
The Outer Assembly is a sweep-type style  with PATTERSON patented pitched product  loaded teflon scraper blades to provide efficient movement of product and transfer of heat.             The Inner Assembly Paddle type two (2)              blade impellers pitched to give lateral              product movement.             To achieve a wide range of rotating speeds,              the equipment is equipped with an AC SCR              Frequency Inverter Speed Control.
B)                Grease Mill (Colloid Mill)
(C)       Heating/Cooling System               including circulation pump and              a modular electronic solid state             temperature controller.  Modular             Electronic Solid State              Temperature Control.  Digital              read out  is  featured  for  clear              and accurate reading of  fluid              temperature.

 

(D)         Vacuum System including vacuum pump to degas the grease to a 
  vacuum level of less than 60 TORR absolute.

 

(E)         Control System.  The basic controller is designed and supplied for 
 manual operation to initiate a process cycle.  All control functions are a 
 panel mounted with safety interlocks.  The Heating/Cooling system has 
 its own control system and control panel.

 

As is readily apparent from the 3D schematic below the system is designed on a 
rack mounted platform so it can be picked up with a fork lift truck.  The frame 
of the system also serves as the shipping frame and during shipment will be 
enclosed with plywood panels.

 

Size of Crate/Skid:            5'0" wide x 4'0" deep x 7'0" high

 

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Turnkey Large Capacity Laboratory Grease Research Skid Mounted System

     Size:  260 mm (10-1/4") I.D. x 432 mm (17") tan line to top of straight side.

     Total Vessel Volume: 6.68 USG

     Total Mixing Capacity: 5 USG = approx. 37.5 lb of Grease at SG of 0.9.    
     All wetted parts 316 stainless steel including 3/4" flush bottom hand wheel  
     operated valve.

     Design Conditions:  Shell 100 psig at 125°C (302°F).

2.  Heating/Cooling System

      Standard Features:

• Flanged Heater.
• Shell & Tube Heat Exchanger for cooling.
• Positive displacement pump.
• Internal fluid bypass to protect the pump and heating element.
• Fused motor protection.
• Fused heater protection.
• Fused transformer protection on both primary and secondary sides.
• Motor overload protection.
• Long life IEC motor starter.
• Microprocessor-based PID controller (dual display).
• Mercury heating Reactor.
• Over temperature protection.
• Thermal Fluid reservoir for filling and expansion.
• Pressure gauge showing delivery pressure to process.
• Pilot lights to indicate separate functions (Power on, Heating and Cooling Functions).
• Equipment built to NEMA 1 Specifications.

      Options & Accessories

• Mechanical seal pump.
• Heating or cooling only functions.
• Increased cooling capacities.
• Increased pumping capacities.
• Controller options to include RS 485 communication.
• Pump reverse.
• Audible or visual alarms.

Schematic Piping Diagram

3.  Homogenizer/Vertical Batch Colloid Mill

    Operating Speed:    7200 rpm/nominal
    Peripheral Velocity: 65 ft/sec (20 m/sec)
    Mill Construction:    All wetted surfaces in 316 S/S. Stator Housing is jacketed 
                                 to allow for heating and cooling
    Hopper Design & Capacity: 1.5 US gallon (5.7 litres) capacity of 316S/S 
                                 complete with Re-circulation tubing and 3 way valve for
                                 discharge with 1" Tri-clamp fitting. 
    Motor Drive:            Direct drive 1/2 HP, 115V/1f/60Hz. 7200 rpm, Open 
                                 Ventilated Universal Motor.  

4.  Vacuum System including vacuum pump to degas the grease at a vacuum 
     level less than 60 torr absolute.  The system includes a single wave 
     Rotary Vacuum Pump including inlet filter and valves.

      Features and Benefits

• Condensor to reflux or remove condensates.
• High pumping capacity over the full vacuum range.
• Compact design,  yet easy to service.
• Air-cooled - no cooling water required.
• Quiet operation.
• Effective oil mist elimination on discharge, exhaust air is 99.9% oil free.
• Built-in non-return check valve, isolates system when pump is stopped.
• Built-in gas ballast valve, permits pumping of water vapor.

• Direct drive, monoblock design, no belts.

5.   Control System    

      The basic control system is designed and supplied 
      for manual operation as far as function initiation.  All control functions 
      are panel mounted with safety interlocks where necessary.  The 
      Heating/Cooling System has its own control system and control 
      panel but is connected to the main control panel (HMI). 

      The control system is micro processor based with an HMI Interface 
      with the following screens:

Complete System consisting of PATTERSON®. Research Grease Kettle, Thermal Fluid Heater/Cooler and Touch Screen Control System, all modules on casters, interconnected with quick-connect hoses and cables.

Modular 17 kg (37.5 lb) capacity PATTERSON Grease Saponification Finishing Kettle   System consisting of  5 USG working capacity PATTERSON Autoclave type Pressurized Grease Reactor Kettle with Double Motion Counter - Rotating Agitator Stirrer basically consisting of a Stationary  Mounted Assembly and Grease Kettle.  Stirrer which can be hydraulically raised and lowered.  All modules are on casters and are interconnected with Quick Disconnect Flexible SS Braided Hoses and Wires.

Total Vessel Volume: 6.68 USG

Total Mixing Capacity: 5 USG = approx. 37.5 lb of Grease at SG of 0.9. All wetted parts 316 stainless steel including 3/4" flush bottom hand wheel operated valve.

Design Conditions:  Shell 1 50 psig at 550°F (287°C).  Jacket (for Thermal Fluid) 100 psig 550°F (287°C)

Please note:  PATTERSON has in-house expertise to design and supply operating control systems for all of our process equipment, whether it is a simple start/stop with cycle time or complex multi-stage systems executing recipes or formulas and communicating with existing plant control systems.

A brief technical overview of the production of 

LUBRICATING GREASES

Description

There has been a need since ancient times for lubricating greases. The Egyptians used mutton fat and beef tallow to reduce axle friction in chariots as far back as 1400 BC. More complex lubricants were tried on ancient axle hubs by mixing fat and lime, but these crude lubricants were in no way equivalent to the lubricating greases of modern times. Good lubricating greases were not available until the development of petroleum-based oils in the late 1800's. Today, there are many different types of lubricating greases, but the basic structure of these greases is similar.

In general, grease consists of a thickening agent dispersed throughout lubricating oil. The thickening agents or gallants include alkali metal soaps, clays, polymers, carbon black, colloidal silica and aluminum complexes. The lubricating oil may be petroleum oil or synthetic oil. The most common type of grease is the soap-based grease. The soap comes from animal or vegetable fats or fatty acids, wool grease, rosin or petroleum acids. The lubricating oil is commonly mineral oil from paraffinic, naphthenic or aromatic hydrocarbons. Other components of these greases include unreacted fat, fatty acids and alkali, unsaponifiable matter (including glycerol and fatty alcohols), rosin or wool grease and water. Some of the other additives used in grease are oxidation inhibitors, rust and corrosion inhibitors, color stabilizers, metal passivators, water repellants and viscosity index improvers.

In soap greases the metallic soap consists of a long-chain fatty acid neutralized by a metal such as aluminum, barium, calcium, lithium, magnesium, sodium or strontium. The fatty acids usually contain 16 to 18 carbon atoms. A common form of soap-based grease uses lithium 12-hydroxystearate as the thickener. To properly thicken the grease the soap must be in the form of fibers of suitable size dispersed throughout the lubricating oil. The crystalline fibers are usually in the size range of 1 - 100 micrometers with diameters 0.1 to 0.01 of their length. For good shear stability the fiber should have a large ratio of length to diameter, and for good oil retention the fiber should be as small as possible. Therefore, greases need a mixture of these two types of fibers. Also, there must be a balance between the solvency of the fluid and the solubility of the soap to get suitable thickening.

Another type of thickener that is not soap-based is prepared from clays. The clay, such as bentonite or attapulgite, is reacted with a quaternary amine to change the clay from hydrophilic (water-loving) to hydrophobic (water-rejecting) and oleophilic (attracting oil). Effective thickening is achieved by combining the clay with a polar activator or dispersant, such as acetone, methanol or ethanol, with small amounts of water and by delaminating and reducing the platelets to a small size. This process will increase the total surface area of the dispersed clay, which immobilizes a very high percentage of oil based on the weight of clay. This will thicken the grease.

Other solid additives produce thickened grease by the nature of their fine dispersion throughout the fluid and by their particle-particle interactions. Solid-additive greases extend the operating temperature range over soap greases. The solid-type greases do not have a melting point, and their upper temperature limit is that of the oil being used.  The melting point of greases made with various soaps will differ appreciably. For example, using the grease dropping-point temperature, which measures temperature limitation of the grease, the following demonstrates the differences in these temperatures: aluminum - 230°F (110°C); sodium - 325 - 350°F (163 - 177°C); calcium (conventional) - 205 - 220°F (96 - 104°C); calcium (anhydrous) - 275 - 290°F (135-143°C); lithium - 350 - 400°F (177 - 204°C).

The dropping temperature of soap-based greases can be increased by using soap complexes. These complexes consist of a soap-salt thickener. For example, an aluminum complex might consist of aluminum with a fatty acid, a nonfatty acid and an alkali. Then each molecule of thickener consists of aluminum complexed with stearate, benzoate and hydroxide. The dropping point of a complex grease is at least 100°F (56°C) higher than the dropping point of the corresponding soap grease. The range of application of greases is also extended by "multi-purpose" greases that consist of mixtures of soap bases or different metals and soaps.

Processing

Greases can be made in either a batch or continuous process. Batch production is the most common manufacturing method. The steps of manufacturing include the following. Bulk ingredients are metered or weighed into the processing reactor. For soap-based greases made by saponification (the process of forming soap by splitting a fat with an alkali), the fatty ingredient, alkali and a portion of the oil are added to the reactor. By heating (300 - 450°F) and mixing, the fat is converted to soap, and the soap is dispersed throughout the mixture. This may be done in open atmospheric PATTERSON double motion stirrer kettles or in closed PATTERSON double motion stirrers. pressure kettles. After completion of saponification and dehydration (removal of water), the remaining oil is added to the batch to lower the temperature. Next, the grease is milled or homogenized. Alternatively for larger operations a PATTERSON Grease Reactor can be used for quick and efficient saponification and after the completion of the cycle the material is transferred to a PATTERSON Double Motion Grease Kettle.  Typically one Reactor will feed 3 Kettles.

The step of homogenization or milling is very important, because it will produce a uniform crystal and gel structure that will not change when the grease is used. Homogenizing the grease will break down the solid particles or fibers and will disperse the resultant small particles in the liquid. It also breaks up lumps, eliminates graininess and produces a smooth product. Homogenization of certain types of greases will stiffen the grease producing lower penetration value.  Homogenization can improve texture and “brighten” a grease’s appearance. In many cases this homogenization process is carried out at temperatures greater than 200°F (93°C).  

After homogenization, the grease is further cooled, deaerated and packaged. Of course, it is understood that there are many different grease manufacturing methods depending on the type of grease and the manufacturer.

APV homogenizers and APV colloid mills or equal can be used for processing grease. The single-stage homogenizer with wear-resistant parts may be operated at up to 10,000 psi. The homogenizer is the preferred piece of equipment for the solid-additive-type greases, because high energy is needed to break up and delaminate the particles such as with clay dispersions. Although a colloid mill can be used to process grease, there are advantages to using the homogenizer. First, the homogenizer is a constant-displacement pump, and its capacity does not vary with different grades of greases. This makes it possible to tie into filling equipment, if desired. The colloid mill must be pump fed and the capacity will be significantly decreased on the stiffer grades of greases.  The homogenizer has sufficient pressure to deliver the grease to any point in the process after it has been homogenized; but a second pump must pick up the colloid mill product, if the grease is to be delivered to another location.

There are other methods of producing grease. A continuous process for grease manufacturing is described in European Patent Specification 0072184B1 (October 29, 1986), which also mentions other continuous methods. These particular techniques will not be discussed here. However, another patented method (US Patent 2,704,363, March 15, 1955) will be briefly described. In this process a homogenizer was used to accelerate the saponification reaction by recycling the batch of ingredients from the reaction kettle through the homogenizer and then back to the kettle. This reduced the reaction time needed to make the grease. In one example given, a batch produced by homogenization was compared to a batch produced by conventional means. The results were that the homogenized batch had an improved consistency; it possessed greater mechanical stability; the operating temperature of the homogenized batch was 320°F compared to 400°F (conventional) and the total operating time was reduced from 18 hours in the conventional fire-cooking process to 3.5 hours for the steam-cooking and homogenization procedure.

Quality and Evaluation

The formulation and processing of grease will determine the type of structure the product has and its physical properties. This is why homogenization can have an important influence on the quality of the grease. There are several desired characteristics for grease such as: body or consistency, stability to shear, surface affinity, thermal stability, flow or viscosity, thixotropy, syneresis, texture and appearance and water resistance. There are many tests that can be performed on grease to measure these properties. One important test is penetration. Penetration is determined by an instrument that measures the depth (in tenths of millimeters) to which a standard cone sinks into the grease under prescribed conditions. Higher penetration numbers indicate softer greases. The National Lubricating Grease Institute (NLGI) uses consistency numbers that correspond to penetration values to classify greases. The numbers are given below.

References

E. Armstrong, US Patent 2,704,363; 1955.
C. J. Boner, C. J. Manufacture and Application of Lubricating Greases, (New York: Reinhold Publishing, 1954) 
1993 APV Homogenizers
A. A. Gordon, European Patent Office 0072184 B1; 1986.
_____________, 1989.  Lubricating Grease Guide, Kansas City: National Lubricating Grease Institute, 1989.


Any statements concerning the use of products or processes described above are made for educational purposes only to further the understanding of grease manufacturing.  They are not to be construed as recommending the infringement of any patent or copyright and no liability for infringement arising out of any such use is assumed by PATTERSON Industries Canada.

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Useful Information from National Lubricating Grease Institute (NLGI) founded in 1933

PATTERSON Industries has been a member of the NLGI for over 20 years.  As stated by President Sandy Cowan during a speech in 2008, "the original mission of NLGI was to distribute information pertinent to the manufacture and use of lubricating grease".  This original mission is still valid today. Besides annual meetings during which new and useful information and a wide assortment of grease related information is published, including the Lubricating Grease Guide and the NLGI Spokesman, NLGI is the source for most technical information concerning lubrication and grease. It is a great example how an industry can work together and exchange important technical information for the benefit of industry in general and the consumer.

Below with the permission of NLGI, we are reprinting a regular feature from the NLGI Spokeman titled "Ask the Expert".

We are mainly reproducing columns that primarily deal with technical information on greases and manufacturing rather than just end user related questions below and trust this is helpful to our customers for Grease Kettles and Reactors: