Lead burning improves the durability of equipment
Simetek manufactured a bottom cone wet electrostatic precipitator to be used at Yara Suomi Oy’s sulphuric acid factory in Siilinjärvi. The current precipitator is repaired by replacing the worn-out bottom cone with a new one. The equipment’s wear resistance was improved by lining the cone’s inner surface with lead plates.
The project was ordered based on the customer’s needs. Simetek’s experts visited the site and initiated the project planning. The customer had already carried out the required imaging.
After material acquisition, we started to manufacture the cone at Simetek’s machine shop using black steel (S355J2G3). The manufacturing process involved sheet metal cutting, edging, sheet rolling and assembly welding. One bolt flange was also fitted into the cone in connection with flame cutting prior to the assembly welding.
“When other stages of the assembly were complete, we started lining the cone’s inner surface with lead,” explains Ville Kinnunen, Project Manager at Simetek.
Lead burning improves load and wear resistance
The cone was lined with lead for several reasons. First of all, the device into which the bottom cone would be placed was originally lined with lead on the inside. Lead burning enabled consistency between the new and the old cone.
According to Kinnunen, lead burning improves the cone’s resistance to loads and wear in comparison to plastic or glass fibre linings which are also used in corresponding applications. In Yara’s case, the low pH value and relatively high flow rate of the sulphuric acid place demanding requirements for the special protection of the device.
“Moreover, lead is a less expensive alternative than special steels that are also used in heavy-wear applications. From the perspective of cost-efficiency, lead lining is the best option.”
The machine shop stage of the project took only approximately two weeks. Lead lining, on the other hand, is remarkably slower. Kinnunen estimates that the lead burning of Yara’s cone requires approximately one month of work from a pair of workers.
Following the cone manufacture, Yara also ordered the cone’s installation which will be implemented in connection with the factory’s annual maintenance in autumn 2020.