Thermal-Hydraulic Characteristics Research And Optimization Design On The Steam-Water Pipeline Network Of Ship Power System

The steam-water pipeline network serves as a bridge and bond in connecting the boilers,turbines,turbo unit,condenser,feed water pump,turbine-generator and other equipment in the ship power system.The thermal-hydraulic properties of the steam-water pipeline network have great effects on the running characteristics of the system.For example,an inappropriate pipeline network layout will lead to the uneven distribution of flow in the pipeline network thus results in a much smaller or larger,unstable steam and water supply for the system,which has directly influence on the normal service of the system and may cause the system to fail.On the other hand,the condensation-water supply pipeline network plays a key role in ensuring the normal operation of the condenser,deaerator,condensate feed water pump and boiler in the ship power system.In the operation of the system should avoid the pressure before the pump is too low,can not reach the saturation pressure of water,causing the water phase change,and even lead to pump cavitation.This paper is focused on the main and auxiliary superheated steam network as well as the condensation-water supply network.The steady-state simulation model of software Flowmaster is adopted to calculate the thermal-hydraulic properties of the main and auxiliary superheated steam network and the hydraulic characteristics of the condensation-water supply network,in order to obtain the running parameters(i.e.,distribution of flow,temperature and pressure)of each device under different working conditions.The obtained results are then compared with the design ones and the network layouts are corrected accordingly.For the cases of uneven flow distribution,the addition throttle orifice strategy or flow control valve is adopted to regulate the flow distribution in the network to match the design claims.Then checked hydraulic characteristics of the condensate water supply network,main study the pressure of the pump before and after the pump,whether beyond the pressure of saturation pressure of water,in order to avoid the cavitation phenomenon.The thermal-hydraulic calculation results show that: the flow distributed from the main and auxiliary superheated steam network to the branch of the steam turbine generator unit and the turbine supercharging set is much larger,while it is much smaller for the main steam turbine one.Thus,a throttle orifice is added before the branch of the steam turbine generator unit and the turbine supercharging set to regulate the flow distribution.The maximum deviation of flow distribution in the pipeline network after optimized is 9.26%,and in most cases,it is below 5%.Moreover,the equipment parameters in the front of the device entrance are equal to the design values,which shows that the optimized network layout is reasonable.In the condensate-water supply pipe network,the throttling orifice is added on the side which has larger flow.The maximum deviation of flow distribution in the network after optimized is below 3%,which also show that the optimized operation is reasonable.In the condenser-water supply network,the pressure value before condensate pump,the saturation pressure are under the corresponding temperature of the water,therefor,must readjust the main condenser water outlet and the water inlet height of condensate pump condenser,after the optimization,the pressure value of the pump reaches the requirement,which also show that the pipeline is reasonable.