Multi-grade oils are important in the lubricating oil industry because they offer low viscosity at low temperatures and thus improved fluidity for cold starts. They also offer high viscosity at high temperatures and thus improved lubricity. The viscosity-temperature dependency should be as low as possible. Multi-grade oils meet these requirements and are widely used in automotive and industrial applications.
Figure 1. Scheme of the LEPD Process

Viscosity index improvers are additives contained in lubricating oils that stabilize the viscosity in a desired range. Polymers—in particular elastic or pseudo-elastic polymers—are frequently used viscosity index improvers that must be effectively melted into the oil in order to develop their desired properties.

Manufacture and Melting of Viscosity Index Improvers

Traditional processes rely on “shear mixing,” in which viscosity index improvers are introduced into the base oil under high temperatures and mechanical forces. However, this can lead to a change in the polymer structure and cause undesirable effects such as turbidity and aging. In addition, the high energy consumption for maintaining the process conditions is problematic.

The new patented LEPD technology is based on an innovative process in which the viscosity index improvers are melted directly in the base oil. The process takes place under mild conditions, at temperatures below 100°C and a pressure of up to 10 bar. The gentle processing preserves the polymer structure and minimizes the risk of turbidity and aging. The technology is more energy efficient and eliminates the need for additional additives, such as antioxidants, in the production process.

The LEPD Process

The process for melting viscosity index improvers takes place in a liquefaction chamber that is operated under pressure with inert gas. In this chamber, the polymer is gently dissolved in the base oil, with continuous circulation of the lubricating oil further forcing the dissolving process and ensuring the even distribution of the polymer content. The liquefaction temperature is below 100°C, which significantly reduces the heat input compared to conventional processes.

In comparison to traditional processes, initial test runs with the new process show several advantages, particularly a shortened process time, increased energy efficiency, significantly reduced noise during production and improved quality of the final lubricating oil.

Economic Considerations and Cost-Benefit Analysis

The process at lower temperatures reduces energy consumption, while the absence of additional additives, such as antioxidants, reduces production costs. This leads to a reduction in costs per unit, especially with large production volumes.

Implementation in the Production Process

To support the implementation of the technology, EDL offers a mobile pilot plant based on which customers can test the process on-site using their own individual formulations. Thanks to its compact dimensions of 2,285 mm width, 2,700 mm height and 5,870 mm length, the plant can be easily transported. With a capacity of 1.2m³ in the melting tank and 1m³ in the base oil storage tank, the pilot plant can produce all common formulations. The test results can then be transferred directly to an industrial scale. The pilot plant allows for a flexible adjustment of the process parameters and ensures that the requested product specifications are met. In the long run, this technology could be established as a standard process in lubricating oil production.

Figure 2. EDL’s Mobile Pilot Plant

Summary

The new technology for melting viscosity index improvers offers significant advantages compared to traditional methods. Gentle processing at low temperatures with significantly reduced shear forces preserves the polymer structure, which improves product quality and gives lubricant manufacturers a competitive edge. Reduced energy consumption and the avoidance of additional additives provide economic advantages and increase the efficiency of lubricating oil production.

Gero Thalemann is project manager for business development and special projects within EDL Anlagenbau Gesellschaft mbH, one of the leading technology-oriented plant engineering companies based in Leipzig, Germany. One of the company’s main focuses is on the development and licensing of proprietary innovative technologies.