Motorbase Case Study

ROSTA Motorbases Type MB 100 on Vacuum Pumps of the New-Sulzer-Burckhardt AG

Aniline, used in the chemical industry primarily as a raw material for the synthesis of colours and synthetic fibres, as well as for the manufacture of artificial rubber schuk and medicines, is technically extracted by the reduction of nitrobenzene, in the presence of iron and hydrochloric acid. For the further processing, the aniline produced is distilled in a vacuum.

The Basel company nsb AG (New-Sulzer-Burckhardt AG), builds very large liquid ring pumps to create a vacuum for industry.

Recently, nsb AG delivered two large radial liquid ring pumps for the extraction of aniline to a customer in the petrochemical industry. The ring pump, driven by eight SPB V-belts, is driven by a 250 kW, 6 pole (1'500 min-1) electromotor, with a housing of 355 M and weight of 1'850 kg. The reduction ratio of the drive motor to the flywheel of the ring pump is 3,75 : 1 (pump speed 400 min-1) and the effective belt length measures 6 metres.

nsb AG wanted to supply their customer with a user-friendly vacuum plant and therefore installed the large 250 kW drive motors on self-adjusting ROSTA Motorbases Type MB 100. Until it reaches its lifespan due to wear, a 6 metre long V-belt is subject to an average elongation, because of age, of approximately 3%, in this case, this is equivalent to a distance of 180 mm. During the first months of operation, without self-adjusting, slip compensating ROSTA motor suspension, the maintenance personnel would have had to compensate for the belt elongation on a weekly basis, in order to guarantee slip-free torque transfer.

For the mentioned drive size, that is equivalent to new adjustment of the motor alignment, expensive maintenance work of approximately 1½ hours for two qualified mechanics. Moreover, the endurance of the belt extends by approximately factor 3 with the self-adjusting mounting of the drive motor; the belts never operate under heat generating slip conditions, do not become warm when operating and will not become glass hard prematurely and brittle, that leads to failure. All in all a user friendly, cost saving investment!

Images:

250 kW drive motor for the fluid ring pump on ROSTA Motorbase Type MB 100.

Installation of the 1'850 kg heavy motor on the motorbase, and tensioning of the eight SPB V-belts by an integrated bevel-gear shaft drive.

This case study was written by ROSTA Ag on 26th February 2008.