The Issue’s Focus: Caspian
Experience in creating high-pressure pumps for oil fields of the Middle East
V.P. Perekhod, Head of Department of Foreign Economic
Activities, JSC NASOSENERGOMASH Sumy
O.V. Rodenko, Director of the program “Rotary pumps for maintenance of reservoir pressure”, Head Research and Development Center, Branch of HMS LIVGIDROMASH JCS
in Moscow city
D.I. Viter, Deputy Director of the program “Rotary pumps for maintenance of reservoir pressure”, Head Research and Development Center, Branch of HMS LIVGIDROMASH JCS
in Moscow city
Introduction
This article describes subjects related to the design, manufacture and testing in accordance with the requirements of international standards of ATNSDp240-1422 pumping units, intended for operation in hard-to-reach areas with severe environmental conditions that require equipment with high reliability and durability.
In the end of 2013 Group HMS concluded a contract for the supply of 7 high-pressure pumps for sea water injection into producing formations in the framework of the implementation of the project on West Qurna-2 (Iraq) field development.
West Qurna-2 field, discovered in 1973, is considered the fourth largest oil field in the world based on oil reserves, which according to some reports amount to approximately 13 billion barrels. The field is located in the South of Iraq, 65 km North-West of the large port city of Basra. Currently participants of the field development project are the national Iraqi oil company South Oil Company and the consortium of contractors, consisting of LUKOIL and national Iraqi company North Oil Company. For LUKOIL this project is the largest international project.
For Group HMS companies, involved in the implementation of the project (JSC NASOSENERGOMASH Sumy, Apollo Goessnitz GmbH), it was also an important stage, which tested technical capacity and the willingness to work and compete on a par with international pumping companies - leaders in the supply of pumping equipment to the the world oil pumping market.
Technical specifications and project requirements were prepared by the Japanese company TOYO Engineering with great care, inherent to Japanese engineers.
Regulatory framework of the project are the internationally recognized standards of design and manufacture, such as:
API 610, 11 edition: Pumps for petroleum, petrochemical and natural gas industry;
API 614: Lubrication systems for machinery of petroleum and petrochemical industry;
API 661: Air-cooled heat exchangers for use in the refining industry;
API 670: Machinery protection systems;
API 671: Special purpose couplings for petroleum, chemical and natural gas industry;
API 682: Shaft sealing systems for use in chemical and petrochemical industry;
ISO 10816-7: Mechanical vibration. Rotodynamic pumps.
NORSOK M-650: Qualification of special materials manufacturers
Technical specification of the structure
The pumping unit consists of TNSDp240-1422 barrel pump, type BB5 on API 610, with a productivity rate of 286 m3/h with 1422 m pressure, electromotor, pressure lubrication installation with air-cooled heat exchanger, temperature control devices and sensors, pressure, vibration monitoring.
Pump and electromotor bearings are lubricated by the oil system complete with two oil pumps - primary, driven by the shaft train of the unit, and booster electric pump, which is required at the time of starting and leading of the system to the operating parameters.
For the oil cooling in the lubrication circuit high-powered air-cooled oil cooler with the duplicate fan is installed.
As the end seals of the pump shaft the tandem dry seals with a locking system applied based on plan 53B according to API 682, with thermosyphon air cooling systems.
All components of the unit, except of air-cooled oil cooler are mounted on a single frame, i.e. in the performance of the SKID.
To ensure the smooth operation each unit is equipped with automation system, including the control of the most important parameters, such as pressure, temperature, vibration of the bearings, axial shift of the rotor.
When designing TNSDp240-1422 pump not only were taken into account and implemented API610 requirements, but also additional requirements of the customer for the operational characteristics. In this regard analysis was performed of the existing liquid end of the commercial pumps, blade wheel adjustment carried out and new distributors developed, optimized combination of the number of blade wheel vanes and channels of distributors, thereby the problem of the blade vibrations solved and overall vibration of the pump improved.
The pump has hydraulically unloaded rotor due to horizontally-opposed arrangement of blade wheels. Residual axial force that occurs as a result of uneven wear of the seal component of blade wheels during the operation, perceived by the axial bearing such as “Mitchell” type with self-aligning pads and leveling system. Such constructive decision allowed to abandon the most unreliable unit in the design of multiple-impeller pump - axial force unloading unit, as well as to reduce the load on axial bearing (compared with the design of the pump with the balance piston). Segmental friction bearings serve as the rotary table bearing, which provide lengthy period of operation and level of vibratory displacement, not exceeding API610 requirements for the pumps of similar class.
Outside case of the pump is designed for maximum possible working pressure, cartridge type internal case, with the possibility of quick replacement on the site of operation without the need to remove the outside case. Special drawout-mounted device is developed for this purpose.
Material used for the pump – D-2 in accordance with API610 (austenitic-ferritic class super duplex steels). This steel is very rare in the application and shows exceptional resistance against corrosion in seawater of the Persian Gulf, that has the highest concentration of chlorides and the aggressiveness. Super duplex steels are not produced by the domestic industry and the requirements for the producers of these materials are very high.
Life-limited parts, such as neck ring bushing and seal component of blade wheels also are made of super duplex steel with the application of special wearproof coating. Owing to its special structure, the coating has special properties not found in the other materials, including high resistance to hydroabrasive wear and low friction coefficient.
Testing
Currently all seven ATNSDp240-1422 units are manufactured and passed benchmark test, which confirmed the correctness of the adopted constructive decisions.
As a result were obtained the required characteristics with a peak value of the pressure at the stagnation point within 120% of the pressure at the rated consumption. Efficiency value, obtained by calculation, confirmed by benchmark tests and are at the level of the maximum achievable for this range of power-speed coefficient.
Obtained vibration characteristics in a broad range of discharge do not exceed acceptable values:
- in nominal rating - vibration speed on thrust chamber not exceeding 2.9 mm/s, shaft displacement vibration not exceeding 36 µm.
- acceptable performance range - vibration speed on thrust chamber not exceeding 3.1 mm/s, shaft displacement vibration not exceeding 46 µm.
Given vibration values comply with the most rigid requirements of ISO 10816-7 standards.
It should be noted that one of the requirements of the customer for the testing of the pump was the measurement of the residual axial force. Special strain gage transducer was developed for this. Measured axial force in nominal rating, as well as on the edge of the acceptable performance range coincided with the data obtained by calculation.
Currently, all pump units are successfully manufactured and delivered to the place of operation.
Summarizing 2 years of work on the project, it is safe to say that great result is achieved and were confirmed the capabilities of JSC NASOSENERGOMASH Sumy, Apollo Goessnitz GmbH and all companies involved in the Group HMS project for creating complex pumping equipment in accordance with the requirements of the world standards, for the toughest operation conditions and the most demanding customers. This is even more important at the present time, when the issues of the entry of domestic enterprises on the international market is very topical.
