Feed Water Pump Control for Combined Cycle Power Plants
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Solution Overview
Problem
Combined cycle power plants face reduced energy efficiency due to pumps being designed for bypass operations, leading to excessive pressure and reduced efficiency in normal operations, as existing configurations do not adequately account for the differences in feed water flow between normal and bypass modes.
Innovation Solution
A combined cycle power plant configuration with a flow regulation valve and control unit that adjusts the feed water flow to the heat recovery steam generator and turbine bypass path, reducing the amount of feed water supplied in bypass mode to match or exceed normal operation levels, thereby optimizing pump capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is designed based on the amount of feed water used in bypass operation, then the pump can discharge the required amount of feed water in bypass operation, but the total head of the pump becomes higher than required in normal operation and the efficiency of the pump is reduced
Solution Approach 1:
The patent applies dynamics by making the feed water flow path configurable through valve control. The system dynamically adjusts between two operational modes: normal operation where feed water flows only to the heat recovery steam generator, and bypass operation where feed water is supplied to both the heat recovery steam generator and the turbine bypass flow path. This dynamic configuration allows the pump to operate at optimal efficiency in normal mode while maintaining sufficient discharge capacity when bypass operation is required.
Solution Approach 2:
The patent changes the flow distribution parameter by controlling the degree of opening of the flow regulation valve. In normal operation, the valve is fully closed, directing all pump output to the heat recovery steam generator. In bypass operation, the valve opens to divert a portion of feed water to the turbine bypass flow path. This parameter change enables the system to adapt pump performance to different operational requirements without redesigning the pump itself.
2Reliability
If the pump is designed based on the amount of feed water used in bypass operation, then the pump can discharge the required amount of feed water in bypass operation, but the discharge pressure of the pump is higher than the required pressure in normal operation
Solution Approach 1:
The system dynamically adjusts the flow path configuration using a flow regulation valve. In normal operation, the valve remains closed, creating a restricted flow path that maintains appropriate discharge pressure. When bypass operation is needed, the valve opens to provide an additional flow path, allowing the pump to maintain its design discharge pressure while directing water to both destinations. This dynamic adjustment prevents excessive pressure buildup in normal operation.
Solution Approach 2:
The feed water flow path is segmented into two separate controllable paths: one leading to the heat recovery steam generator and another leading to the turbine bypass flow path. The flow regulation valve controls the segmentation by directing water to either path based on operational mode. This segmentation allows independent control of flow distribution, enabling the pump to maintain appropriate pressure levels while meeting different discharge requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces pump capacity, improves efficiency, and prevents excessive pressure in normal operations, enhancing overall energy efficiency by aligning pump discharge and head with normal operation requirements.
Implementation Method 1
the steam which has been used to drive the steam turbine is condensed into feed water by a condenser
Implementation Method 2
a heat recovery steam generator generates steam using waste heat from an internal combustion engine
Data Source
AI summary
In the present invention, a coal gasification combined power generation facility comprises: a feed water supply line (72); a condensate pump (39) and an intermediate-pressure feed water pump (40); a turbine bypass line (32) that bypasses a steam turbine and supplies steam to the condenser (73); and a spray water line (76) that supplies the feed water to the turbine bypass line (32). The coal gasification combined power generation facility has a normal operation mode and a bypass operation mode, and in the bypass operation mode, a control device (80) supplies the feed water to the turbine bypass line (32) and performs a first opening degree control to control the opening degree of the supply adjustment valve so that the amount of feed water supplied to the exhaust heat recovery boiler becomes less than that in the normal operation mode.