№10 October 2012Table of contents Issue Archive
№10 October 2012Table of contents Issue Archive
№ 10 (October 2012)
The main objectives in new equipment design is to create a machine with optimum weight and size characteristics and minimal complexity of manufacturing.
By I.B. Tverdokhleb, director of R&D Division, MC GMS Group; V.A. Golovin, chief engineer of the OTPP and PP project for Sumy Plant Nasosenergomash (HMS Group)
At the same time, the designed equipment should operate with the maximum level of efficiency, minimal noise and vibration. It should be of high reliability and maintainability and have a long working life with the requirements of sustainability.
The R&D division of GMS Group, based at Bobruisk Machine Building Plant JSC (HMS Group) upgraded pump 2NPS 65/35-500, 2NPS 120/65-750 2NPS and 200-750 with the above mentioned problems, as well as requirements of API 610, API 682, DIN, ANSI, ISO.
2NPS pumps are designed for pumping oil, petroleum products and other liquids similar to these on the physical and chemical properties, weighing not more than 1,050 kg/cu.m, in a temperature range of -80 C to +200 C and viscosity not exceeding 8.5×10 4 m2 /sec, with the content of suspended particles in an amount of not more than 0.2 percent and a maximum size of 0.2 mm.
The pumps are designed for use in hazardous industries, which can form explosive mixtures of gas, vapor or dust from the air for the category IIA, IIB, IIC and explosion groups T1, T2, T3, T4, GOST 12.1.011.
Pumps can also be used in areas that are prone to seismic activity that does not exceed 9 points on the Richter scale.
2NPS pumps manufactured in climatic design Y, UHL, T category 2, 3 and 4 in accordance with GOST 15150.
The main consumers of pumps and assemblies are the petrochemical industry and oil pipeline transportation.
2NPS pumps feature centrifugal horizontal, multistage ring-section with a longitudinal flat connector (axis) of the body, with the arrangement of the groups opposing impellers. Inlet and discharge pump horizontally on the same level. Joining pipes for pipeline flange (Fig. 1 and 2).
Pump rotor rotates in two bearing supports on ball bearings. Lubricated bearings – liquid, crankcase. Turbine oil T-22C or T-30.
Direction rotor pump – the left (counter-clockwise when viewed from the drive end).
In places where the shaft of the pump housing mounted seal – mechanical (single or double) and packing (with or without the supply inlet barrier fluid).
The drive pump uses asynchronous or synchronous motors explosion-proof with a speed of 3000 rev / min at the current frequency of 50 Hz in (level of protection – not less 2ExdIIAT3). At the customer’s request the unit is equipped with an automatic control system to monitor the health and performance of the automatic control mode during start and stop.
When upgrading pumps to NPCs the design was modified as follows:
– A superior geometry of flow parts (impellers, vanes, inlets, transfer tubes) was used, making it possible to significantly improve the efficiency of the pump, reduce NPSHR, noise and vibration.
– Interchangeable impellers and guide vanes were used, making it possible to significantly expand the range of pumps’ serving and pressure, without replacing the housing and ensuring high efficiency.
– The design of the suction and discharge pipes are made according to DIN, ANSI, ISO.
– The diaphragm design was changed to reduce weight and effectively reduce the impact of axial forces on the rotor in cases of normal and increased clearance of the impeller.
– The flow part’s components are available in three options: carbon steel (option C), chrome steel (option X), chrome-nickel-titanium steel (option H), enabling pumping of various fluids.
– To extend the life of non-durable parts, replacement pump seals were used, made of hard materials in the stator and rotating parts.
– An individual landing of impellers was introduced, with interference on stage shaft. This helped reducing rotor vibration activity and improved the technology of assembly and disassembly of the rotor.
– Sealing of horizontal split case is made “metal on metal”, thus ensuring high reliability sealing.
– Size of the shaft seal is made in accordance with API610, which allows the use of face seals that correspond to API682 and are products of various manufacturers.
– The thermal barrier was redesigned, providing for more effective cooling of the shaft ends to seal and bearings.
– A hard landing of bearings in the pump was introduced, enabling quick and reliable aligning of the rotor and the stator;
– In the bearing supports bearings’ installation, lubrication, cooling, and packing designs were changed to increase reliability and prolong service life.
– A constant level oiler of a new design was used that may be replaced with imported ones.
– Gear coupling on the elastic plate was replaced with more reliable and durable.
– The requirements of API 610 were introduced. A cast iron housing of bearings was replaced with steel; the ends of the drive shafts were made with tapered fit instead of cylindrical one; compression fittings are replaced with flanged; a platform for measuring vibration in three directions was provided, etc.
– The pump attachment to the plate was changed, allowing the free movement of the pump body in case of temperature changes without misalignment with the engine;
– A stiffer overall frame (plate) was used to prevent misalignment of shafts “pump-motor.”
As a result of these activities, the pumps’ efficiency has increased by 5 to 7 percent. This will significantly reduce energy consumption. Operation of only one upgraded 2NPS 200-700 pump will save annually about 300,000 kilowatt-hours of electricity.Significant savings in the operation achieved by increasing the reliability, because MTBF is increased by three times, and the average full service life – by two times.
Production of upgraded pumps 2NPS has been successfully mastered on Bobruisk Machine Building Plant, which is part of the HMS Group
Bobruisk Machine Building Plant JSC (Bobruisk, Belarus) – one of the largest in the CIS manufacturer of centrifugal pumps for petroleum, petrochemical, mining, metals, energy and pulp and paper industries. The factory was founded in 1898. In 2011 it became the part of HMS Group.