Air Cooled Condenser Backpressure Control via Segmented Vacuum
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Solution Overview
Problem
During the start-up of power plants, air-cooled condensers experience backpressure peaks due to trapped air, which can be dangerous and costly to mitigate with existing solutions that require significant capital investment in air ejection equipment.
Innovation Solution
The design incorporates multiple air-cooled condenser modules with controlled steam inlet and vacuum systems, allowing for selective isolation of trapped air volumes and gradual pressure reduction using flow control valves and suction valves to manage backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air ejection equipment capacity is increased to reduce trapped air and backpressure peaks, then backpressure control during start-up is improved, but capital investment and equipment cost increase drastically
Solution Approach 1:
The air cooled condenser is divided into multiple independent streets (first street, second street, etc.), each with its own vacuum system and flow control valves. This segmentation allows selective isolation and evacuation of trapped air from individual streets during start-up, reducing the total air volume that needs to be handled and enabling effective backpressure control without requiring a single large-capacity expensive air ejection system.
Solution Approach 2:
The vacuum system is activated before steam introduction to pre-evacuate trapped air from the condenser streets. Flow control valves are positioned to control steam flow during this preliminary phase, ensuring air is removed before the main steam flow begins, thereby preventing backpressure peaks from forming in the first place.
2Reliability
If multiple vacuum systems with flow control valves are implemented to isolate and evacuate trapped air, then backpressure peaks are reduced during start-up, but device complexity increases
Solution Approach 1:
The condenser is segmented into multiple streets, each equipped with its own vacuum feed and flow control valve. This modular segmentation allows independent control of air evacuation in each street, simplifying the overall system architecture compared to a single complex high-capacity air ejection system, while effectively reducing trapped air volume and backpressure peaks.
Solution Approach 2:
Flow control valves are introduced as intermediary devices between the vacuum system and each condenser street. These valves mediate the steam flow and vacuum application, enabling precise control over the air evacuation process and steam introduction timing, thereby reducing backpressure peaks without requiring overly complex vacuum system configurations.
3Reliability
If steam is slowly introduced during start-up to avoid backpressure peaks, then steam turbine safety is improved, but start-up time and productivity are reduced
Solution Approach 1:
The vacuum system is activated in advance before steam introduction to pre-evacuate trapped air from the condenser streets. This preliminary action removes the harmful air volume before the steam flow begins, enabling faster steam introduction rates during start-up without creating dangerous backpressure peaks, thus improving both safety and start-up time.
Solution Approach 2:
By segmenting the condenser into multiple independently controllable streets with individual vacuum feeds and flow control valves, the system can rapidly evacuate air from each street and control steam introduction to multiple streets simultaneously or sequentially, reducing total start-up time while maintaining steam turbine safety through controlled pressure management.
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 safely and economically reduces backpressure peaks during start-up by isolating air volumes and using controlled vacuum systems to purge non-condensables, preventing high-pressure spikes without the need for expensive equipment upgrades.
Implementation Method 1
a first vacuum system for providing suction pressure to said first and second street
Implementation Method 2
applying a suction pressure to the second street to draw down an internal pressure of the second street
Implementation Method 3
Air is forced over outer surfaces of the tubes so as to cool the tubes and, hence, the steam flowing through the tubes, thus causing the steam to be converted into a liquid condensate
Implementation Method 4
causing the steam to be converted into a liquid condensate
Implementation Method 5
a first flow control valve positioned on said first inlet that controls the flow of steam to said first street
Data Source
AI summary
An air cooled condenser (ACC) system is described having a first street having at least one air cooled condenser module and a second street having at least one air cooled condenser module. The system employs a steam inlet conduit provides steam to the first and second streets. The air cooled condenser system has a standard vacuum system for providing suction pressure to the first and second street. The air cooled condenser system also has an auxiliary vacuum system that provides suction pressure to the first and second streets.