Improvement Design of Marine Steam Circulation Pump

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 has been improved on to resolve a whole range of problems. The circulating pump following such an improvement has undergone a land-based test and seafaring verification inspection and been found to have fully met the preset target concerning its performance.

Key words: turbine circulating pump, improvement, design

1 Introduction

Marine steam turbine circulating pump is mainly composed of steam turbine, reducer and circulating pump three components. Turbine with reducer driven circulating pump work, the seawater suction into the main condenser and the host oil cooler to cool the working fluid. In addition, when the furnace chamber is damaged and leaking, the pump serves as an emergency drainage pump to discharge the accumulated water in the cabin out of the vessel.

Turbine by the rotor and the shell composition, the rotor is equipped with blades, reducer pinion gear and to provide lubrication of the bearing gear pump and other components. The housing is equipped with a nozzle box, a quick-closing valve, a first auxiliary valve, a second auxiliary valve, a diaphragm, a turbine seal, a support bearing and a thrust bearing.

The reducer is also composed of a rotor and a housing. The rotor is equipped with reducer gear, speed measuring device, supporting bearing and thrust bearing. Shell is also equipped with components such as oil cooler.

The circulating pump is still composed of a rotor and a housing. The rotor is provided with a pump wheel (ie a work wheel), a rubber supporting bearing and the like. In order to facilitate the maintenance, the shell is composed of two halves, the vertical middle face is bolted, the shell includes the pump shell, the first half guide, the second half guide, the pump cover, the water inlet part and other components.

2 to improve the design of the proposed

2.1 Turbine steam turbine circulation pump speed control valve by a quick-closing valve, the first auxiliary valve control two nozzles, through the two valves to complete the pump operating conditions. The second auxiliary valve controls three nozzles, open for use when overloaded or when the steam turbine parameters are reduced, or as a backup valve. As the three valves are manual valves, which not only heavy workload, but also difficult to achieve automatic control. In order to solve this problem, the quick-closing valve to self-control valve to increase the role of regulating valve, the other two valves do not change. After the operation of the measure found that there are still two problems: First, the larger size of the quick-closing valve in the small opening state, it is easy to automatically shut down; the second is the valve control more dispersed, when the ship in reverse, to Manually open a auxiliary valve for control, so you can not fully realize the positive and reverse automatic control, so still need to be further improved. 2.2 The original pump on the oil cooler heat pipe easily damaged at the joint easily detached.

2.3 The original circulating pump two plain bearings for the rubber bearings. As the processing technology behind the rubber and copper casting adhesive performance is poor, very low manufacturing yield, which requires improved design.

2.4 The original steam turbine support the existence of the upper end of the lack of fuel supply situation, oil performance needs to be improved in the design to be improved.

2.5 According to the equipment development mission statement: The pump shaft speed of 260r / min, found a horizontal vibration resonance peak, and at its speed, the pump shaft vibration was also found to be more intense, so that the pump is difficult to work properly, which Need to find out the reasons for improving the design, to be resolved.

2.6 In order to improve the running performance, an electric oil pump is added, which is used when the unit is started and stopped.

2.7 In addition, some parts of the processing technology needs to be improved to further improve the performance of steam turbine circulating pump.

3 to improve the design

3.1 electric control valve to improve the design

First improved design of the nozzle box, the original speed off the valve no longer directly control the nozzle, only the role of the main steam valve and the speed off valve, it can manually switch and automatic, manual speed control, cancel the speed control function; the original speed One nozzle controlled by the valve and two nozzles controlled by the first auxiliary valve are controlled by a newly designed electric regulating valve. The original second auxiliary valve is still reserved, called the auxiliary valve, the role of the same.

The newly designed electric control valve driven by the electric actuator, through the gear reducer gear, the combination of the size of the valve stem valve for horizontal movement, the valve opening and closing, play a role in regulating steam turbine intake. Into the small opening into the steam, small valve superior control ability to give full play. Electric actuator with local handwheel, you can manually control the electric control valve in place, also has electronic control box, you can remotely control the electric valve, you can also control the room through the microcomputer control of the electric valve. The electric control valve regulating function can fully meet the main steam turbine is reversing the conditions of the various conditions, so the steam circulation pump to achieve the start-up, operation and shutdown automation.

3.2 Oil cooler heat pipe solution to the problem

First of all, the reason why the heat exchanger tube of the oil cooler is easy to break is analyzed. The main reason is that the B30 pipe is rubbed, collided and collided with other parts in the process of production, installation and transportation, Long-term exposure to seawater, seawater pollutants will remain in the damaged dent, the formation of electrochemical corrosion under the action of sea water, so that the damage of B30 tube thinner and even the final rupture. Therefore, a specific requirement has been formulated that manufacturers should be required to produce, install and transport according to technical requirements so as to avoid such accidents.

Cooler tube heat exchanger easily detached, the analysis is the quality of the expanded tube. After a large number of rigorous tests and calculations will be expanded tube force control in a certain range, so that both can seal expansion, without leaving the joints at the pipe to maintain the original intensity range, will not crack.

3.3 rubber bearing the solution

The original cast rubber bush castings using ordinary cast, prone to defects, pass rate is low; rubber and copper casting bonding technology, but off, prone to rubber stripping on the copper castings, product inspection, the pass rate of less than 50 %. After the improvement of copper casting centrifugal casting, the fine grain of the casting, arranged closely, all the castings are cast once qualified, therefore, improve the casting quality. Adhesion of rubber and copper casting also adopts modern technology formula and scientific and efficient production management, the production of rubber bearing the passing rate increased to 90%.

The original lower rubber bush water chamber radius R3, now changed to R8, cooling water flow through the area increased 1.4167 times; original upper rubber bush water chamber radius R5, now changed to R10, cooling water flow through the area increased by 1.28 times, so Make the rubber bush have more cooling water to be cooled and lubricated, so as to avoid sticking on the shaft. 3.4 Lack of oil supply problem solution

The gear pump oil supply and the bearing and gear transmission fuel consumption one by one were calculated, the calculation results show that the normal supply of gear pump oil. Turbine top bearing due to insufficient oil supply bearing temperature is too high, because the bearing away from the pump, the tubing flow area is too small, resulting in increased pipeline loss caused by the upper bearing oil supply pipe diameter From Φ16 to Φ19. In the trial, the top bearing oil temperature is always within the normal range.

3.5 vibration solution

The first critical speed of the steam turbine rotor is calculated to be 13

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