Steam Power Plant Low Load Operation via Steam Extraction
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Solution Overview
Problem
Steam power plants operating at low load face inefficiencies and increased costs due to temperature and pressure fluctuations, leading to sub-optimal economic and environmental performance.
Innovation Solution
The method involves tapping steam between superheaters to stabilize temperatures and pressures, allowing for minimal changes during load variations, and utilizing the extracted energy for other processes to enhance efficiency and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam is generated at low load, then the steam generator operates at reduced capacity, but the temperature at the outlet of the hot reheater sinks and live steam temperature decreases
Solution Approach 1:
The patent extracts steam from the steam generator at a point between the superheaters, removing a portion of the steam flow. This extraction allows the remaining steam to maintain higher temperatures through improved convective heat transfer in the superheaters, thereby resolving the temperature drop issue at low load conditions while still providing the required power output.
Solution Approach 2:
The patent changes the operating parameters by reducing the steam flow rate through the superheaters while maintaining or increasing the temperature differential. This parameter change enables the steam generator to operate efficiently at low load without sacrificing temperature stability, as the reduced flow allows better heat transfer coefficients to dominate the thermal process.
2Loss of energy
If steam is tapped from the steam generator, then energy is extracted for other processes, but the temperature stability may be affected
Solution Approach 1:
The patent strategically extracts steam from a specific location between the superheaters rather than from earlier stages. This positioning ensures that the extraction occurs after the steam has been sufficiently heated and stabilized, allowing energy recovery while minimizing impact on temperature stability. The extracted steam carries away heat energy that would otherwise be lost, improving overall system efficiency.
Solution Approach 2:
The steam extraction point acts as an intermediary element that balances energy recovery needs with temperature stability requirements. By positioning the extraction point optimally, the system can transfer energy to external processes while the remaining steam flow continues to maintain stable temperatures through enhanced convective heat transfer mechanisms.
3Use of energy by stationary object
If the plant operates at low load, then energy consumption increases, but efficiency and economic performance deteriorate
Solution Approach 1:
The patent converts the typically harmful effect of low load operation (temperature drops, reduced efficiency) into a beneficial situation by exploiting the reduced steam flow to enhance convective heat transfer coefficients. This allows the steam generator to operate more efficiently at low load than conventional systems, as the lower flow rates enable better thermal contact and heat transfer, thereby reducing energy consumption while maintaining productivity.
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 approach maintains stable steam parameters, improves convective heat transfer, and increases overall efficiency by recovering energy, enabling higher load gradients and reducing energy demand and emissions.
Implementation Method 1
In a steam generator (1) under utilization of fossil fuels or by means of biomass out of the feed water live steam is generated
Implementation Method 2
In a steam generator (1) under utilization of fossil fuels or by means of biomass out of the feed water live steam is generated
Implementation Method 3
which is expanded in a steam turbine (3) and thus drives a generator G
Implementation Method 4
After expanding the steam in turbine (3), it streams into a condenser (5) and is liquefied there
Implementation Method 5
The condensate originated in condenser (5) is then supplied, by a condensate pump (7), to several preheaters VW1 to VW5
Implementation Method 6
With the heat exchange between tapping steam and condensate the temperature of the condensate increases
Implementation Method 7
In the evaporator (13) the condensate is heated and becomes saturated steam
Implementation Method 8
In the evaporator (13) the condensate is heated and becomes saturated steam
Implementation Method 9
In order to counteract the Joule-Thomson-Effect at the control valves of Partial-Arc-Turbines the boiler pressure p LS can be reduced
Data Source
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AI summary
A method for operating a steam power plant at low load is suggested comprising the extraction of live steam LS before the last superheater SH3 and/or resuperheated steam before the last resuperheater RSH2 and using the thermal energy of this steam in other heat sinks. Thus, nearly constant steam parameters of the live steam LS are achieved and the overall efficiency of the steam power plant remains at a high level.