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Eliminating Feedwater Control Valve Damage with Multi-stage, Multi-path Flowserve Control Valves
The feedwater control valve (located downstream of the high-pressure feedwater heaters) performs the critical function of controlling the feedwater flow rate over a wide range of service conditions. During startup and shutdown, the feedwater control valve restricts flow by controlling near the closed position. The pressure drop across the valve is high, which can cause severe cavitation and noise. Over time, these severe service conditions will damage a control valve. Even a properly designed valve will not work well unless it is connected to a correctly sized actuator. An undersized actuator will cause unstable flow conditions while an oversized unit has a slow response to input signals. Flowserve has successfully addressed these issues with specially engineering multi-stage multi-path, or MSMP, designs. MSMP trim channels the flow through a series of orifices to reduce the pressure in stages. This prevents cavitation from occurring inside the valve. The velocity of the feedwater is kept low to prevent erosion of the valve body and to reduce noise and vibration. MSMP trim is customer-designed for the full range of service conditions. MSMP trim prevents cavitation when throttling near the seat but acts like a conventional control valve when controlling near the full-open position. As the pressure drop across the valve decreases, the cavitation also decreases and then stops. To maintain flow rate with decreasing pressure drop, the valve will open further and expose flow paths without orifices. The orifices are not needed at this flow condition because cavitation has stopped.
Revision Date: 8/3/2015
Tags: 221118 - Other Electric Power , 221118 - Other Electric Power , Flowserve, Valve, Actuator, Boiler Feedwater System, High Performance Valve, Cavitation, Noise, Vibration
Power Plant Cooling Webinar - Hot Topic Hour November 13, 2014
The webinar focused on the decisions power plants will make relative to steam cooling at both new and existing facilities.
Revision Date: 11/13/2014
Tags: 221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, Nalco, Ovivo USA, National Energy Technology Laboratory, Research Cottrell Cooling, Kiewit, Clarifier, Water Intakes, Water Quality Modeling System, Boiler Feedwater System, 316(b), Regulation, Efficiency, Water Reuse, Wastewater Reuse, Heat Recovery, Water Treatment, Water Conservation
Barbara discussed a number of past initiatives to use alternative water sources such as treated municipal wastewater and to recover heat from the flue gas. Several ongoing projects include COHO which would both recover heat and capture CO2.
Revision Date: 11/13/2014
Tags: 221112 - Fossil Fuel 化石燃料, 221112 - Fossil Fuel 化石燃料, National Energy Technology Laboratory, Boiler Feedwater System, Water Reuse, Heat Recovery, Water Conservation, Wastewater Reuse
The reducing environment produced by oxygen scavengers initiates and propagates flow-accelerated corrosion (FAC) in the feedwater system and other components of high-pressure steam generators, including heat recovery steam generators (HRSGs). Since 1986, FAC-induced attack has caused numerous failures, some with fatalities, at a number of power plants in the U.S. Yet, specifications for many new power plants both domestically and globally, and in which the condensate/feedwater system contains no copper alloys, continue to call for oxygen scavenger feed to the condensate. This document is a response to this misguided trend.
Revision Date: 8/25/2014
Tags: 221112 - Fossil Fuel 化石燃料, Kiewit, Boiler Feedwater System, Heat Recovery Steam Generator, Ultrapure Water, Corrosion, Demineralization, Boiler Feedwater Treatment, Degasification