Squeaky Clean

Challenge

Cleaning open-gears with large girth-gear diameters that drive ball mills or rotary kilns is usually a very dirty and time-consuming process, especially when people are using ‘black grease or oil’ (aluminium complex greases with graphite or asphaltic product).

Open gears generally need to be cleaned for three reasons:

• When a maintenance shutdown is due to take place, in order for an inspection to be performed.
• To prevent abrasive wear by removing contamination. Efficient lubrication must be performed on clean and unpolluted surfaces. Abrasive wear may cause the loss of material on the gear drives due to the presence of hard particles suspended in the lubricant. This may cause serious damage to the gears’ working flanks.
• When switching from a ‘black product’ to a high-viscous transparent or white fluid, which are becoming the most common service lubricants in the field.

A mill can easily be stopped, however it takes an average of 48 hours to clean the open-gear using traditional solvent. Moreover, using a traditional solvent product when the mill is running, before shutdown, would damage the gear.

The kiln runs at extremely high operating temperatures of between 1400°C and 1500°C, therefore it cannot just be stopped. Instead, there must be a gradual running down process, and only following this would it usually be safe to start the cleaning process, with operators scrubbing each of the girth gear teeth manually, taking 48 hours. Beginning the cleaning process with traditional solvent products before the end of the cool-down period would damage the gear.

Solution

Total Lubrifiants, with help from Lubrilog, has proposed a solution to cleaning these gears without stopping the production. LUBRICLEAN EP enables gears to be cleaned while they are in operation, without the need to shut down equipment, therefore saving production time. The solution features extreme pressure properties, meaning cleaning can start during the equipment cool-down period for a kiln or during operation for a mill, rather than waiting for it to be stopped. It offers cost-effective cleaning and protection of the gears’ working flanks.

Health and safety are of paramount importance across the cement industry, therefore the product is non-toxic, protecting both employees and the environment from chlorine and volatile organic compounds (VOCs). Meticulous planning for any type of maintenance activity in an operation of this scale is essential for it to be successful. Preparatory meetings with representatives from the company and personnel from across cement plant engineering and maintenance teams must take place before the operation. Every aspect, from timings to safety, must be thoroughly planned to ensure the most successful outcome.

Cleaning methodology

Cleaning during operation can be performed on any type of lubrication system (permanent or intermittent). The job begins with the preparation of the operation by installing waste product collection tanks.

After having stopped the spraying system or draining the lubricant in case of splash or circulation lubrication, the Lubriclean EP will be sprayed by an operator using a high-pressure pump through the inspection door of the Out (lifting) pinion and In (pressing) pinion if double drive. It will be sprayed from one side to another of the gear as well as on the edges. This operation will take around 1 hr using three or four drums of Lubriclean EP to fully clean the gear and casing.

After the cleaning, the teeth are covered with an extreme pressure protection film. The equipment can either be stopped for maintenance or inspection or can continue in operation, using the lubrication spraying system continuously for a few hours or refilling the tank in case of splash lubrication.

Total Lubrifiants is able to supply a cleaning kit including PPE, High Pressure Pump, and drums of Lubriclean EP for one operation.

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Read the article online at: https://www.worldcement.com/special-reports/30042020/squeaky-clean/