When pumping IIC category fluids in explosive and fire-hazardous areas, GOST 31839-2012 requires the use of leak-proof pumps. In practice, leak-proof pumps are frequently used where the use of double face seals pumps is permitted.
R&PC "ANOD" specialists have developed options for upgrading leak-proof pumping units.
The structurally upgraded pumping unit consists of a centrifugal pump's hydraulic part with a bearing seal block docked thereto, a rack with auxiliary system equipment, a plate coupling, and an electric drive assembled on a single frame.
The BSB is a cylindrical housing with single seals installed at the endpoints, which perform the functions of the contour and barometric stages of the double seal. Thrust and journal sliding bearings are located between the seals and are cooled and lubricated by the barrier fluid. The materials of sliding bearings and friction couples of seals - silicon carbide, tungsten carbide, carbon graphite, and hardened steel in various combinations - ensure the rubbing couples' reliable operation.
In upgraded pumping units, the tightness of the barrier fluid circuit is monitored, allowing for the prevention and elimination of pumped fluid leaks into the atmosphere.
A typical example would be upgrading a pumping unit with an HMD magnetic coupling. This unit pumps a gasoline-toluene mixture at temperatures ranging from 180° to 260° C.
The pump supporting part and magnetic coupling was replaced with a bearing seal block (BSB) and a plate coupling, while the flow part of the pump and the impeller remained unchanged.
The operational conditions of sliding bearings have significantly changed due to the use of BSB with autonomous lubrication and cooling circuit. The bearings now operate in a clean barrier fluid having good lubricating properties, in preference to operating in the pumped fluid, which can contain airlocks, abrasive particles, and corrosive wear.
The excluded losses associated with the use of magnetic coupling and the recirculation of a portion of the pumped fluid for bearing lubrication enabled the power consumption to be lowered from 120 kW to 97 kW, and the enterprise saved hundreds of thousands of rubles a year just on electricity.
The mean time before failure has increased several times, while the costs associated with pump repair have decreased.
On industrial safety
( Federal Law 116 "On Industrial Safety of Hazardous Production Facilities")
During the refurbishment of sealed pumps and pumps with magnetic couplings using BSB, the pump is transferred from one category - a sealed pump - to the category of a conventional pump with a double face seal. This modification is made to the unit's design documentation and is subject to an industrial safety examination.
