The majority of pumps, being in operation nowadays, was developed in the middle of XX cent., and pump units manufacturing uses engineer decisions and techniques, having been tested for decades, inspite of quite a limited unit scope and range of working parameters.
Though, nowadays the development of technological processes significantly increases a list of requirements for pumps and their effectivity, within enlarged Q-H working range. It touches upon the problem of pump operability at higher mechanical and heat loads, in movable part joints, as well as the question of development and appliance of new antifrictional materials and improvement of frictional units.
Lots of scientific centres and research institutes try to make a contribution, when solving the problems of increased pump operability. Different investigations, relating to tribology of ceramic solids, nano- and superdispersed materials and composites with improved operational characteristics, are regularly carried out. Results of the investigations give the opportunity to develop new models of pumps – with plain bearings and mechanical seals, instead of rolling bearing assemblies.
The importance of such investigations is surely confirmed by an interest some foreign companies display. So, in 2009 John Crane announced the purchasing of Orion Corporation, one of the leading designers and producers of hydrodynamic bearings for various industries. In connection with this fact, quick appearance of pumps with mechanical seals and plain bearings can surely be expected. Sulzer implements a concept of feed pumps retrofit, which also concerns pressure casing’s improvement, installation of mechanical seals, relieved plugs and plain bearings, working with the water pumped.
Due to the experience, while designing and exploiting of friction pairs (including these ones in mechanical seals), ANOD’s specialists got the opportunity to develop new generation pumps with increased overhaul life at hard service conditions. Instead of a traditional rolling bearing assembly, some new modifications of bearing seal blocks BPU with plain bearings and mechanical seals were developed. BPU are to be applied in the pumps of oil-and-gas, petrochemical and power industries.
Two single seals of the block construction allow to work in a clean buffer fluid, as if double or “tandem” seals. In case a seal is installed only at a driver’s end, the block can operate with a medium pumped. Mainly, blocks are to be installed into overhung and between-bearing pump types, in horizontal or vertical shaft position.
Friction pairs, in the majority of cases, are silicon carbide – silicon carbide or graphitized carbon – hardened steel (with specific pressure of 3 to 20 bar). That considerably reduces wear-out of the bearings. Liquid lubrication and rejection of heat delivered by friction pairs, is performed by means of extraneous heat-exchanges or SBTU reservoirs, analogous to the reservoirs, applied in mechanical seal support systems.
Support system of BPU provides for heat rejection out of the block, without destruction of friction pair rings and bearing sleeves, even in case of a “hot” pump stop and consequent start-up. So, the following results can be achieved when BPU are used:
So, such pump type successfully demonstrated its reliability, while working at oil-and-gas, power and chemical enterprises. That resulted in good reputation and increased demand for the pumps.