Economic Design of Hybrid Wet-Dry Cooling Systems

2013 ◽  
Author(s):  
R. W. Card
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Weather Data ◽  
Net Generation ◽  
Steam Turbines ◽  
Cooling Systems ◽  
Hybrid Cooling ◽  
Seasonal Basis ◽  
Dry Cooling

A hybrid wet-dry cooling system can be designed for a large combined-cycle power plant. A well-designed hybrid cooling system will provide reasonable net generation year-round, while using substantially less water than a conventional wet cooling tower. The optimum design for the hybrid system depends upon climate at the site, the price of power, and the price of water. These factors vary on a seasonal basis. Two hypothetical power plants are modeled, using state-of-the-art steam turbines and hybrid cooling systems. The plants are designed for water-constrained sites incorporating typical weather data, power prices, and water prices. The principles for economic designs of hybrid cooling systems are demonstrated.

scholarly journals Studying the Reduction of Water Use in Integrated Solar Combined-Cycle Plants

2019 ◽  
Vol 11 (7) ◽  
pp. 2085 ◽  
Author(s):  
Fontina Petrakopoulou ◽  
Marina Olmeda-Delgado
Keyword(s):  
Water Consumption ◽  
Power Plants ◽  
High Efficiency ◽  
Cooling System ◽  
Combined Cycle ◽  
Special Focus ◽  
Cooling Systems ◽  
Cooling Fluid ◽  
Hybrid Cooling ◽  
Dry Cooling

With vast amounts of water consumed for electricity generation and water scarcity predicted to rise in the near future, the necessity to evaluate water consumption in power plants arises. Cooling systems are the main source of water consumption in thermoelectric power plants, since water is a cooling fluid with relatively low cost and high efficiency. This study evaluates the performance of two types of power plants: a natural gas combined-cycle and an integrated solar combined-cycle. Special focus is made on the cooling system used in the plants and its characteristics, such as water consumption, related costs, and fuel requirements. Wet, dry, and hybrid cooling systems are studied for each of the power plants. While water is used as the cooling fluid to condense the steam in wet cooling, dry cooling uses air circulated by a fan. Hybrid cooling presents an alternative that combines both methods. We find that hybrid cooling has the highest investment costs as it bears the sum of the costs of both wet and dry cooling systems. However, this system produces considerable fuel savings when compared to dry cooling, and a 50% reduction in water consumption when compared to wet cooling. As expected, the wet cooling system has the highest exergetic efficiency, of 1 and 5 percentage points above that of dry cooling in the conventional combined-cycle and integrated solar combined-cycle, respectively, thus representing the lowest investment cost and highest water consumption among the three alternatives. Hybrid and dry cooling systems may be considered viable alternatives under increasing water costs, requiring better enforcement of the measures for sustainable water consumption in the energy sector.

Hybrid Cooling for Thermal-Electric Power Generation

2013 ◽  
Author(s):  
John S. Maulbetsch
Keyword(s):  
Cooling System ◽  
Meteorological Data ◽  
Combined Cycle ◽  
Plant Performance ◽  
Design Parameters ◽  
Water Requirements ◽  
Cooling Systems ◽  
Capital Costs ◽  
Hybrid Cooling ◽  
Dry Cooling

Water use by power plant cooling systems has become a critical siting issue for new plants and the object of increasing pressure for modification or retrofit at existing plants. Wet cooling typically costs less and results in more efficient plant performance. Dry cooling, while costing more and imposing heat rate and capacity penalties on the plant, conserves significant amounts of water and eliminates any concerns regarding thermal discharge to or intake losses on local water bodies. Hybrid cooling systems have the potential of combining the advantages of both systems by reducing, although not eliminating, water requirements while incurring performance penalties that are less than those from all-dry systems. The costs, while greater than those for wet cooling, can be less than those for dry. This paper addresses parallel wet/dry systems combining direct dry cooling using a forced-draft air-cooled condenser (ACC) with closed-cycle wet cooling using a surface (shell-and-tube) steam condenser and a mechanical-draft, counterflow wet cooling tower as applied to coal-fired steam plants, gas-fired combined-cycle plants and nuclear plants. A brief summary of criteria used to identify situations where hybrid systems should be considered is given. A methodology for specifying and selecting a hybrid system is described along with the information and data requirements for sizing and estimating the capital costs and water requirements a specified plant at a specified site. The methodology incorporates critical plant and operating parameters into the analysis, such as plant monthly load profile, plant equipment design parameters for equipment related to the cooling system, e.g. steam turbine, condenser, wet or dry cooling system, wastewater treatment system. Site characteristics include a water budget or constraints, e.g. acre feet of water available for cooling on an annual basis as well as any monthly or seasonal “draw rate” constraints and meteorological data. The effect of economic parameters including cost of capital, power, water and chemicals for wastewater treating are reviewed. Finally some examples of selected systems at sites of varying meteorological characteristics are presented.

Towards a Technoeconomic Framework for Estimating Cost-Performance Tradeoffs for Power Plants Incorporating Transformative Dry-Cooling Technologies

2016 ◽  
Author(s):  
Geoffrey Short ◽  
Addison K. Stark ◽  
Daniel Matuszak ◽  
James F. Klausner
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Fresh Water ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Cooling Systems ◽  
Natural Gas Combined Cycle ◽  
Evaporative Cooling System ◽  
Dry Cooling

Fresh water withdrawal for thermoelectric power generation in the U.S. is approximately 139 billion gallons per day (BGD), or 41% of total fresh water draw, making it the largest single use of fresh water in the U.S. Of the fresh water withdrawn for the power generation sector, 4.3 BGD is dissipated to the atmosphere by cooling towers and spray ponds. Dry-cooled power plants are attractive and sometimes necessary because they avoid significant withdrawal and consumption of freshwater resources that could otherwise be used for other purposes. This could become even more important when considering the potential effects of climate change (1). Additional benefits of dry-cooling include power plant site flexibility, reduced risk of water scarcity, and faster permitting (reducing project development time and cost). However, dry-cooling systems are known to be more costly and larger than their wet-cooling counterparts. Additionally, without the benefit of additional latent heat transfer through evaporation, the Rankine cycle condensing (cold) temperature for dry-cooling is typically higher than that for wet-cooling, affecting the efficiency of power production and the resultant levelized cost of electricity (LCOE). The Advanced Research Projects Agency - Energy (ARPA-E) has developed a technoeconomic analysis (TEA) model for the development of indirect dry-cooling systems employing steam condensation within a natural gas combined cycle power plant. The TEA model has been used to inform the Advanced Research in Dry-Cooling (ARID) Program on the performance metrics needed to achieve an economical dry-cooling technology. In order to assess the relationship between air-cooled heat exchanger (ACHX) performance, including air side heat transfer coefficient and pressure drop, and power plant economics, ARPA-E has employed a modified version of the National Energy Technology Laboratory (NETL) model of a 550 MW natural gas combined cycle (NGCC) plant employing an evaporative cooling system. The evaporative cooling system, including associated balance of system costs, was replaced with a thermodynamic model for an ACHX with the desired improved heat transfer performance and supplemental cooling and storage systems. Monte Carlo simulation determined an optimal ACHX geometry and associated ACHX cost. Allowing for an increase in LCOE of 5%, the maximum allowable additional cost of the supplemental cooling system was determined as a function of the degree of cooling of the working fluid required. This paper describes the methodologies employed in the TEA, details the results, and includes related models as supplemental material, while providing insight on how the open source tool might be used for thermal management innovation.

Inlet Air Cooling Applied to Combined Cycle Power Plants: Influence of Site Climate and Thermal Storage Systems

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi
Keyword(s):  
Power Output ◽  
Parametric Analysis ◽  
Power Plants ◽  
Cooling System ◽  
Thermal Storage ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Cooling Systems

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.

Performance Enhancement of Solar Air Conditioners Using Hybrid Heat Rejection System

2019 ◽  
Author(s):  
Abdul Ahad Iqbal ◽  
Ali Al-Alili
Keyword(s):  
Air Conditioning ◽  
Cooling System ◽  
Vapor Compression ◽  
Summer Period ◽  
Cooling Systems ◽  
Hybrid Cooling ◽  
Vapor Compression Cooling ◽  
Air Conditioning Systems ◽  
Sorption Systems ◽  
Dry Cooling

Abstract The performance of air conditioning systems is highly dependent on the environmental conditions of the high pressure side, where heat is rejected to the environment. Air conditioning systems utilize dry cooling systems which often don’t provide adequate cooling during peak cooling periods, or wet cooling systems which consume a lot of water. In this study, a novel hybrid cooling system that can provide both wet and dry cooling was modelled in TRNSYS, and used to provide cooling to closed sorption air conditioning systems. The performance of these systems with the hybrid cooling system was compared to the performance of a standard vapor compression cooling system being cooled by a dry cooling system. The COPsol of the vapor compression cooling system exhibited a decrease of almost 26% during the summer period, whereas the COPsol of the sorption systems increased by around 30%. Similarly, the cooling capacity of the vapor compression cooling system dropped by almost 5%, and for the sorption systems, it increased by around 20% during the summer period.

scholarly journals Economic Analysis of a Zero-Water Solar Power Plant for Energy Security

2021 ◽  
Vol 11 (20) ◽  
pp. 9639
Author(s):  
Eduardo de la Rocha Camba ◽  
Fontina Petrakopoulou
Keyword(s):  
Power Plant ◽  
Energy Security ◽  
Power Plants ◽  
Net Present Value ◽  
Solar Power ◽  
Cooling System ◽  
Solar Power Plant ◽  
Levelized Cost Of Electricity ◽  
Cooling Systems ◽  
Dry Cooling

Water dependency of power plants undermines energy security by making power generation susceptible to water scarcity. This study evaluates the economic performance of a novel dry-cooling system for a water-independent solar power plant. The proposed cooling system is based on the concept of earth–air heat exchangers, approaching zero environmental impact. The viability of the proposed design is discussed based on both costs and benefits, and it is compared to both conventional dry- and wet-cooling systems. The installation costs of the plant are found to be EUR 13,728/kW, resulting in the substantial levelized cost of electricity of EUR 505.97/MWh. The net present value of the studied design assuming a water-cost saving of EUR 1/m3 is found to be MEUR –139.59. Significantly higher water prices in the future might eventually make the proposed system economically attractive when compared to water-cooling systems. However, the new system would require drastic modifications to become more attractive when compared to existing dry-cooling systems. Specific possibilities to improve it for zero-water use in thermoelectric power plants are further discussed.

Integrated Diagnostic System for the Equipment of Power Plants: Part I — Formulation and Algorithms

2002 ◽  
Author(s):  
J. Kubiak ◽  
A. Garci´a-Gutie´rrez ◽  
G. Urquiza ◽  
G. Gonza´lez
Keyword(s):  
Expert System ◽  
Expert Systems ◽  
Gas Turbines ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Rotor Bearing ◽  
Bearing System ◽  
Plant Efficiency

The output capacity of combined cycle power plants is reduced in many cases, and sometimes forced to outages, when its main components are affected by faults, i.e., when the rotating equipment such as turbines, generators, compressors, pumps and fans suffer a failure. Normally, the overall reduction of the efficiency, and sometimes the component efficiencies, is monitored but it is difficult to identify the primary causes of the fault of the specific equipment that causes the reduction of plant efficiency. Therefore, to reduce the time of faulty operation, a precise diagnostic tool is needed. One such tool is an expert system approach, which is presented in this work. It consists of several expert systems for the identification of the faults caused by deterioration of the inner parts of the equipment, Fig. 1. Such faults not only reduce the plant efficiency but in many cases also increase the vibrations of the rotor-bearing system. Based on knowledge, the various expert systems have been constructed and their algorithms (efficiency reduction) developed for the following equipment: steam turbines, gas turbines and compressors, condenser, pumps and water cooling system. An expert system for detecting faults that increase the vibration of the rotor–bearing system is also presented. As far as the turbo compressor expert system is concerned the fault hybrid patterns previously developed were implemented and described elsewhere [1].

Cost/Performance Comparisons of Water Conserving Power Plant Cooling Systems

2011 ◽  
Author(s):  
John S. Maulbetsch
Keyword(s):  
Combined Cycle ◽  
Operating Costs ◽  
Large Reduction ◽  
Cooling Systems ◽  
Cost Performance ◽  
Direct System ◽  
Hybrid Cooling ◽  
Combined Cycle Plant ◽  
Power Plant Cooling ◽  
Dry Cooling

This paper documents the results of a study of alternative cooling systems for electric power generating plants to understand the tradeoffs between wet, dry and hybrid cooling technologies. Results are presented through case studies of a 500 MW coal plant, a 600 MW nuclear plant and a 500 MW gas-fired combined-cycle plant, each at five different sites. Alternative cooling systems are configured and optimized for each site. For optimized designs under nearly all conditions, wet cooling systems are not only the least expensive but result in the highest plant output and efficiency. For both all-dry and hybrid systems, the system using indirect dry cooling has higher capital and operating costs than one using the direct system. The use of either dry or hybrid cooling can result in a large reduction in the amount of water used by a plant. The savings cost approximately $7 to $10 million per year for plants of the specified size, depending on the plant and site implying a breakeven water cost of $3 to $6 per thousand gallons.

scholarly journals Investigation of Thermo-Flow Characteristics of Natural Draft Dry Cooling Systems Designed with Only One Tower in 2 × 660 MW Power Plants

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1308
Author(s):  
Mohan Liu ◽  
Lei Chen ◽  
Kaijun Jiang ◽  
Xiaohui Zhou ◽  
Zongyang Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Cooling System ◽  
Flow Characteristics ◽  
Cooling Systems ◽  
Natural Draft ◽  
Wind Speeds ◽  
Flow And Heat Transfer ◽  
Power Load ◽  
Dry Cooling

In recent years, natural draft dry cooling systems with only one tower have been adopted in some 2 × 660 MW power-generating units owing to the advantage of lower construction costs. The operating cases of two power-generating units and one power-generating unit will both appear based on the power load requirement, which may lead to very different flow and heat transfer performances of this typical cooling system. Therefore, this research explores the local thermo-flow characteristics of air-cooled heat exchangers and sectors, and then analyzes the overall cooling performance of the above two operating cases under various wind conditions. Using the numerical modeling method, the results indicate that the flow and heat transfer performance of this cooling system decreases significantly in the case of one unit with half sectors dismissed. At wind speeds lower than 8 m/s, the difference in turbine back pressure between two units and one unit appears obviously higher than in other wind conditions, even reaching 4.37 kPa. Furthermore, the air-cooled heat exchanger in the lower layer always has better cooling capability than that in the upper layer, especially in conditions where there is an absence of wind and under low wind speeds. The operating case of one unit is not recommended for this dry cooling system because of the highly decreased energy efficiency. In conclusion, this research could provide theoretical support for the engineering operation of this typical natural draft dry cooling system in 2 × 660 MW power plants.

Consideration of the Environmental Impact of Wet vs Dry Cooling for Combined Cycle Power Plants

2014 ◽  
Author(s):  
A. G. Howell
Keyword(s):  
Environmental Impact ◽  
Power Plants ◽  
Combined Cycle ◽  
Regulatory Agencies ◽  
Cooling Systems ◽  
Increasing Trend ◽  
Carbon Dioxide Co2 ◽  
The Impact ◽  
Dry Cooling ◽  
Selection Of

Combined cycle power plants fueled with natural gas have been increasingly preferred by regulatory agencies for new power generation projects, compared with traditional coal-fired plants. With growing concerns about water resource availability and the environmental impact of wet cooling systems, there has been an increasing trend for new combined cycle projects to incorporate dry cooling, often as a mandate for regulatory approval of the project. There appears to be little consideration given to the impact of less efficient dry cooling systems on unit efficiency, and particularly on increased fuel requirements and therefore carbon dioxide (CO2) emissions for a given power generating output. The trade-off between reduction of water use and increased fuel requirements with dry cooling should be included as part of the decision on the selection of cooling systems for new fossil plant construction.

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