**Abstract:**
This paper presents an improved design for a marine steam turbine circulating pump, addressing several long-standing issues in its original design and manufacturing process. The enhanced version of the pump was tested both on land and during sea trials, and it successfully met all the performance targets set during the design improvement phase.
**Classification:** TK264.1 | **Document Code:** A
**Article ID:** 1001-2060 (2000) 02-0137-03
**Improved Design of a Marine Steam Turbine Circulating Pump**
Qiu Zufa, Gao Lei, Qin Xiaocheng
(Harbin No.703 Research Institute)
**Abstract:**
The design and production technology of a marine steam turbine circulating pump have been enhanced to address various operational challenges. Following the improvements, the pump underwent land-based testing and seafaring verification, confirming that its performance fully meets the intended design goals.
**Keywords:** turbine circulating pump, improvement, design
**1. Introduction**
A marine steam turbine circulating pump typically consists of three main components: the steam turbine, the reducer, and the circulating pump itself. The turbine, in conjunction with the reducer, drives the pump to draw seawater into the main condenser and the host oil cooler, helping to cool the working fluid. Additionally, in the event of a furnace chamber leak, the pump can function as an emergency drainage system to remove accumulated water from the ship’s compartments.
The turbine is composed of a rotor and a housing. The rotor includes blades, a pinion gear, and a lubrication pump for the bearings. The housing contains a nozzle box, a quick-closing valve, auxiliary valves, a diaphragm, turbine seals, support bearings, and thrust bearings.
The reducer also has a rotor and a housing, with the rotor equipped with reduction gears, a speed measuring device, and bearings. The housing includes an oil cooler and other necessary components.
The circulating pump is made up of a rotor and a housing. The rotor features a pump wheel (work wheel) and a rubber-supported bearing. To facilitate maintenance, the housing is split into two halves, connected by bolts along the vertical mid-plane. It includes the pump casing, guide vanes, pump cover, and inlet sections.
**2. Proposed Improvements in Design**
2.1 The original speed control valve was replaced with an electric control valve, reducing manual intervention and improving automation. However, initial tests revealed some issues, such as valve instability at small openings and difficulty in achieving full reverse control. These were further refined.
2.2 The oil cooler’s heat exchanger tubes were prone to damage due to poor installation practices and corrosion from seawater. This led to frequent failures and required better quality control during manufacturing and transport.
2.3 The original rubber bearings had low manufacturing yield due to poor adhesion between rubber and copper castings. This issue was resolved through improved casting techniques and advanced bonding methods.
2.4 The turbine's upper bearing lacked sufficient oil supply, leading to overheating. This was addressed by increasing the diameter of the oil supply pipe.
2.5 Vibration issues were identified at certain speeds, particularly around 260 rpm. This required structural modifications to eliminate resonance and ensure stable operation.
2.6 An electric oil pump was added to improve reliability during start-up and shutdown phases.
2.7 Several machining processes were optimized to enhance overall performance and durability.
**3. Implementation of the Improved Design**
3.1 The new electric control valve was designed to replace the previous manual valves, enabling automatic regulation of steam flow. It features remote and local control options, significantly improving operational efficiency.
3.2 To prevent heat exchanger tube failures, stricter manufacturing and handling standards were introduced. The expansion process was refined to ensure proper sealing and reduce joint failure.
3.3 The rubber bearings were redesigned with larger cooling water channels, enhancing cooling and lubrication, thus reducing the risk of shaft sticking.
3.4 The oil supply system was modified to increase the diameter of the oil line, ensuring adequate lubrication for the turbine’s upper bearing.
3.5 Vibration problems were mitigated through detailed dynamic analysis and structural adjustments, resulting in smoother and more stable operation of the turbine rotor.
**Conclusion**
Through comprehensive design and technological improvements, the marine steam turbine circulating pump has achieved significant performance enhancements. The changes not only resolve previous operational issues but also improve reliability, safety, and efficiency, making it more suitable for demanding maritime environments.
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