Jet Pump Condensate Recirculation in Combined Cycle Plants
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Solution Overview
Problem
Gas and steam turbine systems face efficiency and corrosion issues due to sulfuric acid condensation from fuels with high sulfur content, requiring large recirculation pumps that reduce power and efficiency, especially when sulfur content increases.
Innovation Solution
The system employs a jet pump to recirculate condensate by using medium-pressure feedwater as a propellant, mixing it with condensate, and adjusting temperatures through heat exchangers and bypass lines to maintain dew point without electrical pumps, allowing for efficient condensate preheating and reducing component complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate electrically driven recirculation pumps are used to recirculate condensate, then the condensate temperature is maintained above the dew point, but the power output and efficiency of the power plant are reduced
Solution Approach 1:
The system uses the existing feedwater pump's pressure energy to drive condensate recirculation through a jet pump, eliminating the need for separate electrically driven recirculation pumps. The feedwater pump serves dual purposes: supplying feedwater and driving condensate recirculation, thereby preventing corrosion without additional power consumption.
Solution Approach 2:
A jet pump is introduced as an intermediary device that uses the pressure energy of the feedwater pump to recirculate condensate. The jet pump converts the kinetic energy of the feedwater into a suction effect that draws condensate from the condensate preheater outlet and delivers it to the inlet, enabling recirculation without direct electrical drive on the condensate pump.
2Reliability
If larger recirculation pumps are used to handle higher sulfur content, then corrosion prevention is improved, but the loss of power and efficiency increases significantly
Solution Approach 1:
The system changes the operating parameters by using the feedwater pump's existing pressure head (approximately 60 bar) to drive the jet pump, which then recirculates condensate at the required flow rates. This approach allows the recirculation system to adapt to varying sulfur content requirements without increasing power consumption, as the jet pump's performance can be adjusted by modifying the feedwater flow rate or jet pump geometry.
3Temperature
If higher-grade heat is used for condensate preheating, then the minimum condensate inlet temperature is maintained, but the heat is no longer available for steam production
Solution Approach 1:
The system extracts the pressure energy from the feedwater pump that would otherwise be wasted, and uses it to drive condensate recirculation. This extracted energy enables the system to maintain condensate temperature requirements while preserving the thermal energy in the exhaust gas for steam production, as no additional high-grade heat needs to be diverted.
4Temperature
If steam is tapped from the steam turbine for condensate preheating, then the condensate temperature requirement is met, but the output and efficiency of the gas and steam turbine plant decrease
Solution Approach 1:
The system uses the kinetic energy from the feedwater pump to drive condensate recirculation, making the recirculation process self-powered without requiring external steam extraction. The feedwater pump's pressure energy is utilized to create the recirculation flow, eliminating the need to tap steam from the steam turbine and preserving plant output.
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 solution significantly reduces the need for large recirculation pumps, enhances efficiency, and minimizes corrosion by maintaining condensate temperatures above the dew point, improving overall system performance and reducing operational costs.
Implementation Method 1
a jet pump is to be used to utilize this previously lost pressure energy. This jet pump uses the medium-pressure feedwater mass flow as a motive fluid after it has passed through the fuel preheater, thereby drawing in condensate from the condensate preheater outlet
Implementation Method 2
The resulting mixture flow is added to the condensate flow before it enters the condensate preheater heating surfaces of the waste heat steam generator, thus raising the temperature of the total mass flow
Implementation Method 3
heat transfer is determined from the water side, i.e., The flue gas-side pipe wall temperature corresponds approximately to the internal condensate temperature
Data Source
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AI summary
The invention relates to a combined cycle turbine plant (1) having at least one gas turbine (2), a steam turbine (3) and at least one waste heat steam generator (4), the waste heat steam generator (4) comprising at least one condensate pre-heater (5) into which a condensate line (6) discharges, and comprising a feed water pre-heater (8) which is connected upstream of the condensate pre-heater (5) in the flow direction of a gas turbine flue gas (7) and upstream of which, on the feed water side, there is connected a feed water pump (9), and which is connected to a fuel preheating unit (10) for the gas turbine (2), wherein from the fuel preheating unit (10) a line (11) for cooled feed water discharges into a motive medium inlet (12) of a jet pump (13) of which the suction medium inlet (14) is connected to an outlet (15) of the condensate pre-heater (5) and of which the outlet (16) is connected to the condensate line (6). The invention also relates to a corresponding method for condensate recirculation in a combined cycle turbine plant (1).