Many chemical enterprises, refineries and steel works intensely use sealless pumps for transferring of toxic, radioactive and hazardous mediums. GOST R 52743-2007 obliges binds enterprises to apply sealless pumps while transferring of mediums IIC, as per hazard and explosiveness zone classification. If other mediums, pumps with double or “tandem” mechanical seals may be applied.
Though, practically, sealless pumps are often used in cases where it’s not necessary. Efficiency of sealless pumps is lower, as compared with common types. A working medium should not contain solids or fibers which can deteriorate plain bearing and protective jackets, clogg cooling channels or change axial force balance that influences the rotor. Sealless pumps do not permit modes at a dry start-up and absence of a working medium in pump’s cavity, and require for well-developed automatic control system. Repair of sealless pumps on-site is almost impossible due to design peculiarities and specific construction.
Considering the importance of safety, long overhaul life and effectiveness of pump equipment, R&PC “ANOD” developed modifications of ANGK pump type which lack the disadvantages mentioned above, and, in the majority of cases, can serve as an alternative to sealless pumps.
Structurally, such ANGK pump type modification contains a hydraulic part of a centrifugal pump, coupled with BPU bearing-seal block, mounting stand with support system equipment and an electromotor, assembled on a single base plate. BPU is a cylindrical body, with single seals at its ends that function as contour and atmospheric steps of a double or “tandem” seals (depending on the duty executed). Between seals there are support and thrust plain bearings, cooled and lubricated by the medium pumped. Materials, used in plain bearings and seal friction pairs (silicon carbide, tungsten carbide, graphitized carbon and hardened steel) provide for reliable work even in contaminated mediums. Pumps with BPU units constitute 5- ANGK pump series which can operate in a large Q-H working range: at capacities of up to 1200 m3/h and heads up to 350 m. At any service mode, there is leakage control of a buffer fluid contour of ANGK pump units. That helps to prevent and even exclude leakage of a pumped medium into environment. Developed BPU units are compatible with horizontal or vertical shaft positions. Appliance of BPU essentially reduces shaft distance between bearing supports and increases its rigidity.
All these advantages put 5- ANGK pump series as advanced Russian development which is distinguished by increased vibration characteristics and overhaul life, reduced maintenance and repair costs, 3…5% lower power consumption. Besides, effectiveness of 5- ANGK pump series appliance is increasing when regarding questions of import substitution and retrofit on the basis of customer’s pumps, being already in operation, with rolling bearings. Appliance of BPU units at power, chemical and petrochemical enterprises brought positive results.
So, ANGK pump units are getting more popular. Since 2004 BPU units have been in operation for more than 1 million hours. Nowadays, in many cases, sealless pumps can be successfully replaced by 5- ANGK pumps with higher reliability and leak-proof characteristics.