The objective of this report is to make up for the following deficiencies at least on a general level – while still using first principles.
Air-cooled condensers are widely used at the cold end of thermal power cycles. With this equipment cooling water required in wet cooled power plants may be saved on a large scale. To operate fans which convey dry cooling air to the condenser modules electric power is required which reduces overall power plant effectiveness. Consequently, pumping power consumption should be as small as possible. During operation it is therefore common to reduce fan power consumption by switching down or off fans of individual modules or, in some case complete ACC streets if ambient conditions and operation parameters are promising.
Performance guarantees are normally specified with all equipment in full action. Only primary variable variations such as ambient temperature, ambient air pressure or total steam flow rate for a reduced range at fan full speed are part of the performance guarantee. Therefore, effects of fan switch or high cross-wind levels remain open issues.
Table of Contents
1 Introduction
2 ACC Layout
3 General ACC Model
4 ACC Steam Duct
5 Constant Exhaust Pressure
6 Variation of Fan Speed
7 Cross Wind
8 Cross-Wind – Pressure Drop
9 Cross-wind – Recirculation
10 Summary
Objectives & Core Topics
The primary objective of this report is to provide a comprehensive, physics-based mathematical framework for assessing the operational performance of air-cooled condensers (ACCs). It specifically addresses the impact of variable ambient conditions, fan speed adjustments, and cross-wind effects to assist manufacturers in design considerations and operators in optimizing power plant performance without relying solely on complex, site-specific computational fluid dynamics simulations.
- Mathematical modeling of standard and induced-draft ACC configurations.
- Performance estimation under fluctuating ambient temperatures and pressures.
- Evaluation of fan power optimization through speed variation and switch-off procedures.
- Analysis of cross-wind effects, including pressure drops and hot air recirculation.
Excerpt from the Book
1 Introduction
As a consequence of increased environmental awareness dry air-cooled condensers (so-called ACC’s) have gained wide acceptance in the realm of thermal power plants. Saving of cooling water is the main reason for this development.
In the past the investment for ACC’s was nearly fourfold the cost of classical wet cooling systems. Lots of improvements over traditional technology have contributed to their success. Among other things, fin tube performance (multi row to single row) have been upgraded as well as steam side flow configuration (co-current, counter-current), steam side ducting and last not least fan design (high efficiency, low noise). Procedures for optimizing fin tube geometry as well as ACC design may be found as an example in quotation [1].
All these refinements have been made to reduce cost and to gain superior operation characteristics. To this end, it is indispensable to know the performance at varying operational conditions. ACC suppliers therefore have to provide performance diagrams at change of different primary variables - such as ambient air temperature, barometric pressure or steam side flow rate as a base framework.
Summary of Chapters
1 Introduction: Provides an overview of the rise of dry air-cooled condensers due to water conservation and details the necessity of performance modeling for varying operational conditions.
2 ACC Layout: Discusses the traditional forced-draft two-pass ACC configuration and the newer induced-draft three-pass variant, highlighting their architectural differences and operational advantages.
3 General ACC Model: Establishes the fundamental thermodynamic model for ACC modules based on first principles, regardless of the steam side arrangement.
4 ACC Steam Duct: Details the calculation of pressure changes from the module inlet back to the turbine exhaust to ensure accurate performance modeling.
5 Constant Exhaust Pressure: Presents a linearized approach for solving turbine exhaust pressure as a function of heat duty, extending the validity of performance diagrams.
6 Variation of Fan Speed: Analyzes the consequences of adjusting fan speeds to optimize power consumption during part-load operations.
7 Cross Wind: Introduces the three primary detrimental effects of cross-wind: profile maldistribution, additional pressure drops, and hot air recirculation.
8 Cross-Wind – Pressure Drop: Examines how wind affects the airside pressure drop and provides methods for assessing the impact on fan performance and potential stall.
9 Cross-wind – Recirculation: Investigates the mixing of recirculated hot air with fresh air and its effect on the effective temperature difference at the condenser inlet.
10 Summary: Concludes the report by synthesizing the derived equations and methods for practical use in both the planning and operational phases of power plant management.
Keywords
Air-Cooled Condenser, ACC Design, Operation of ACC, Cross-Wind Effect, Forced Draft, Induced Draft, Heat Transfer, Thermodynamics, Fan Performance, Ambient Conditions, Recirculation, Power Plant Effectiveness.
Frequently Asked Questions
What is the core focus of this publication?
The book provides a systematic, physics-based approach to modeling the performance of air-cooled condensers (ACCs) across various configurations and environmental conditions.
What are the central themes of the work?
The work focuses on thermal performance, energy minimization through fan control, and the mitigation of negative environmental impacts like cross-wind interference.
What is the primary objective of the research?
The goal is to move beyond site-specific computational simulations and provide ACC manufacturers with general, reliable rules and formulas to predict performance variations.
Which scientific methods are utilized?
The author primarily employs first-principle thermodynamic modeling, linearization of the Antoine equation for saturated steam, and analytical geometry assessments.
What topics are covered in the main body of the document?
The main body covers architectural layout, steam duct pressure losses, fan speed control, and a detailed mathematical breakdown of wind-induced performance degradation.
Which terminology is most critical to understanding the book?
Key terms include heat duty, relative fan speed, exchanger effectiveness, cross-wind resistance factors, forced vs. induced draft, and recirculation rates.
How does the book treat the difference between forced and induced draft?
The book distinguishes between these by defining specific area ratios and geometry-based recirculation variables that reflect the unique behaviors of each configuration.
Does the author provide tools for practical application?
Yes, the author includes several performance diagrams (Types 1, 2, and 3) that allow users to derive turbine exhaust pressures based on varying heat duty and air temperatures.
- Quote paper
- Hans Georg Schrey (Author), 2024, Air-Cooled Condenser Operation under Varying Ambient Conditions, Munich, GRIN Verlag, https://www.grin.com/document/1450374
