Experimental Study on a Packed Bed Humidifier in an Evaporative Gas Turbine

2002 ◽  
Author(s):  
Farnosh Dalili ◽  
Mats Westermark
Keyword(s):  
Mass Transfer ◽  
Water Vapor ◽  
Gas Turbine ◽  
Boiling Point ◽  
Pilot Plant ◽  
Air Flow ◽  
Hot Water ◽  
Compressed Air ◽  
Transfer Unit ◽  
Exhaust Heat

This paper examines the performance of gas turbine cycles operating with a mixture of air and water vapor. Special attention is paid to the humidification tower, where the water vapor is added to the air. The experiments in this study have been carried out in the first evaporative gas turbine pilot plant located at Lund Institute of Technology in the southern part of Sweden. This pilot plant is based on a Volvo VT600 gas turbine with a design load of 600 kW. The compressor pressure is just above 8 bars and the intake air-flow is 3.4 kg/s. Roughly 70 percent of the compressed air is humidified in the humidification tower, which is the only humidifying device. The tower diameter is 0.7 m and the total flexible packing height is 0.9 m of a stainless steel structured packing with a specific surface area of 240 m2/m3. The number of mass transfer units in the humidifier was experimentally determined to about 3 for a packing height of 0.45 m. The height of a transfer unit from the literature data for the packing is predicted to be 0.24 m. With a packing height of 0.45 m, only about 2 transfer units are expected from the packing. However, the droplet zones above and below the packing contribute about 1 transfer unit. Thus, it is concluded that the mass transfer performance of the packing is adequately predicted by literature data. Equations are provided to adjust the height of a transfer unit for other pressures and temperatures. For full-scale plants operating at higher pressures and temperatures it is suggested that the high quality exhaust heat, (temperatures above the boiling point) is recovered in a boiler and injected as steam. The remaining part of the exhaust heat, (temperatures below the boiling point) is used to produce hot water for a relatively small humidification tower using only a portion of the compressed air flow.

Experimental and Theoretical Results of a Humidification Tower in an Evaporative Gas Turbine Cycle Pilot Plant

2002 ◽  
Author(s):  
Torbjo¨rn Lindquist ◽  
Marcus Thern ◽  
Tord Torisson
Keyword(s):  
Mass Transfer ◽  
Gas Turbine ◽  
Heat And Mass Transfer ◽  
Pilot Plant ◽  
Operating Conditions ◽  
Compressed Air ◽  
Water Evaporation ◽  
Operating Pressure ◽  
Simultaneous Heat ◽  
Theoretical Results

The Evaporative Gas Turbine Pilot Plant has been in operation at Lund Institute of Technology in Sweden since 1997. In this cycle low-grade heat in the flue gases is utilized for water evaporation into the compressed air in the humidification tower. This result in, amongst others, power augmentation, efficiency increase and lower emissions. This article presents the experimental and theoretical results of the humidification tower, in which simultaneous heat and mass transfer occurs. A theoretical model has been established for the simultaneous heat and mass transfer occurring in the humidification tower and it has been validated with experiments. The humidification tower in the pilot plant can be operated at several operating conditions. An after-cooler makes it possible to chill the compressor discharge air before entering the humidification tower. The saturation temperature of the incoming compressed air can thereby be varied from 62 to 105 °C at the operating pressure of 8 bar(a). It has been shown that the air and water can be calculated throughout the column in a satisfactory way. The height of the column can be estimated with an error of 10% compared with measurements. The results from the model are most sensitive of the properties of the diffusion coefficient, viscosity and thermal conductivity due to the complexity of the polar gas mixture of water and air.

Design Study of Part Flow Evaporative Gas Turbine Cycles: Performance and Equipment Sizing: Part 1 — Aeroderivative Core

2001 ◽  
Author(s):  
Niklas D. Ågren ◽  
Mats O. J. Westermark
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
High Efficiency ◽  
Air Flow ◽  
Compressed Air ◽  
Column Height ◽  
Detailed Model ◽  
Testing Stage ◽  
Equipment Sizing ◽  
Temperature Levels

The evaporative gas turbine cycle is a new high efficiency power cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The system presented also includes live steam production and superheating by heat from the hottest flue gas region. The humidifier only uses the lower temperature levels flue gas heat, where it is best suited. The analyzed system is based on data for the aeroderivative Rolls Royce Trent as a gas turbine core. Part 2 of this 2-part paper presents the results based on data for the industrial gas turbine ABB GTX100. Simulation results include electric efficiency and other process datas as functions of degree of part flow. A detailed model of the humidifier is also used and described, which produces sizing results both for column height and diameter. Full flow humidification generates an electric efficiency of 51.5% (simple cycle 41%). The efficiency increases when the humidification air flow is reduced, to reach a maximum of 52.9% when air flow to the humidification amounts to around 12% of the intake air to the compressor. At the same time, total heat exchanger area is reduced by 50% and humidifier volume by 36% compared to full flow humidification. This calls for a recommendation not to use all the compressed air for humidification.

Study on Heat Transfer From Hot Water to Cold Air With Evaporation

2013 ◽  
Author(s):  
Tatsuya Yamaji ◽  
Tatsuya Hirota ◽  
Yasuo Koizumi ◽  
Michio Murase
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Flux ◽  
Water Flow ◽  
Air Flow ◽  
Temperature Drop ◽  
Hot Water ◽  
Convection Heat ◽  
Cold Air ◽  
Evaporation Heat

Evaporation heat transfer from hot water flow to cold air flow in a horizontal duct was examined. Experiments were performed for turbulent condition. The test flow channel was rectangular. The width, height and length were 40 mm, 20 mm and 1,000mm. The length of heat transfer surface was 140 mm. In experiments, hot water was in the range of 40 °C ∼ 60 °C. Cold air was approximately at 20 °C. The air velocity was varied from 1.61 m/s ∼ 10.5 m/s. Heat transfer rate from hot water flow to cold air flow became large with an increase in air velocity. The higher the water temperature was, the larger the heat transfer rate was. When total heat flux from water to air flow was divided into two terms; the evaporation term and the forced flow convection term, the evaporation term dominate main part and that was about 60 ∼ 80 % of the total heat flux. Water surface temperature drop from bulk water temperature was confirmed. However, the temperature drop was less than 5 °C. The surface temperature drop had little effect on the evaporation heat flux and the convection heat flux. The measured evaporation heat flux was lower than the value predicted with the mass transfer correlation that was developed through analogy between heat transfer and mass transfer. The measured convection heat flux was higher, approximately twice, than the value that was calculated with the correlation for turbulent flow heat transfer probably because of bottom heating. The method to predict the heat transfer from the hot water flow to the cold air flow with the evaporation was developed by modifying the turbulent flow mass transfer correlation and the turbulent forced convection heat transfer correlation. Good results were obtained.

scholarly journals Design of Tubular Humidifiers for Evaporative Gas Turbine Cycles

1998 ◽  
Author(s):  
Farnosh Dalili ◽  
Mats Westermark
Keyword(s):  
Heat Transfer ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Water Film ◽  
Compressed Air ◽  
Tube Length ◽  
Finned Tubes ◽  
Recovery Potential ◽  
Air Stream ◽  
Exhaust Heat

In the evaporative gas turbine (EvGT) cycle, also referred to as the humid air turbine (HAT) cycle, the compressed air is humidified with water to increase the mass flow through the expander, resulting in high power output and high exhaust heat recovery potential. This paper presents a design methodology for tubular humidifiers, in which pressurized air is led inside of smooth metallic tubes and is brought into contact with a falling water film. The heat required for humidification is mainly taken from exhaust gas from the gas turbine on the shell side and also by recirculating water through the intercooler and the aftercooler. The most important parameters for designing tubular humidifiers are: heat transfer coefficient on the flue gas side; and mass transfer coefficient for water vapor on the air side. Important design aspects include: proper wetting of the tubes; how to avoid flooding of the tubes; entrainment of water droplets into the air stream; and boiling in the water film. All calculations in this paper are based on an evaporative gas turbine cycle applied for combined heat and power generation with a partial-flow humidification circuit, where a fraction of the compressed air is humidified while a major part is by-passed directly to the recuperator. It is concluded that the required heat exchanging surface can be reduced if humidification is carried out for only a fraction of the air (20–30 percent). Finned tubes are recommended to enhance the heat transfer per unit tube length.

Feasibility Study of an Innovative Micro Gas Turbine With a Swiss-Roll Recuperator

2006 ◽  
Author(s):  
Hsin-Yi Shih ◽  
David Wang ◽  
C.-Ron Kuo
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Axial Flow ◽  
Thermal Characteristics ◽  
Engine Performance ◽  
Thermal Design ◽  
Micro Gas Turbine ◽  
Fuel Consumption Rate ◽  
Transfer Unit ◽  
Exhaust Heat

Feasibility of an innovative micro gas turbine with heat recuperation has been studied. The proposed core engine has back-to-back rotor configuration formed by a centrifugal-flow compressor and an axial-flow turbine. A newly Swiss-roll recuperator is wrapped around a can-type combustor to recover the exhaust heat, thus reducing the fuel consumption rate and improving the engine thermal efficiency. From the recuperated cycle analysis, thermodynamic requirements at both inlet and outlet of each component were predetermined to evaluate the engine performance. The conceptual design and preliminary analysis to achieve these requirements were made, component-by-component. The thermal design of the Swiss-roll recuperator was also carried out by theoretical analysis, which gives the thermal characteristics of the recupeator, including the trend of effectiveness, thermal requirement of number-of-transfer-unit (NTU) and the preliminary sizing with the number of turns and the width of the flow channels be determined. The characteristics of Swiss-roll recuperator resemble the counter-flow spiral plate heat exchanger and basically have the excellent performance with high effectiveness and low pressure loss. The performance of the proposed micro gas turbine was investigated, and potentially a compact micro gas turbine with thermal efficiency higher than 20% is possible for the power output less than 10 kW.

Design Study of Part-Flow Evaporative Gas Turbine Cycles: Performance and Equipment Sizing—Part I: Aeroderivative Core

2002 ◽  
Vol 125 (1) ◽  
pp. 201-215 ◽  
Author(s):  
N. D. A˚gren ◽  
M. O. J. Westermark
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
High Efficiency ◽  
Air Flow ◽  
Compressed Air ◽  
Column Height ◽  
Detailed Model ◽  
Testing Stage ◽  
Equipment Sizing ◽  
Temperature Levels

The evaporative gas turbine cycle is a new high-efficiency power cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The system presented also includes live steam production and superheating by heat from the hottest flue gas region. The humidifier only uses the lower temperature levels flue gas heat, where it is best suited. The analyzed system is based on data for the aeroderivative Rolls Royce Trent as a gas turbine core. Part II of this two-part paper presents the results based on data for the industrial gas turbine ABB GTX100. Simulation results include electric efficiency and other process datas as functions of degree of part flow. A detailed model of the humidifier is also used and described, which produces sizing results both for column height and diameter. Full flow humidification generates an electric efficiency of 51.5% (simple cycle 41%). The efficiency increases when the humidification air flow is reduced, to reach a maximum of 52.9% when air flow to the humidification amounts to around 12% of the intake air to the compressor. At the same time, total heat exchanger area is reduced by 50% and humidifier volume by 36% compared to full flow humidification. This calls for a recommendation not to use all the compressed air for humidification.

Experimental Determination of the Heat Recovery Boiler Effectiveness of a Gas Turbine Plant

2014 ◽  
Vol 659 ◽  
pp. 503-508
Author(s):  
Sorin Gabriel Vernica ◽  
Aneta Hazi ◽  
Gheorghe Hazi
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Heat Recovery ◽  
Heat Recovery Boiler ◽  
Experimental Point ◽  
Experimental Data Processing ◽  
Turbine Plant ◽  
Transfer Unit ◽  
Gas Turbine Plant ◽  
Recovery Boiler

Increasing the energy efficiency of a gas turbine plant can be achieved by exhaust gas heat recovery in a recovery boiler. Establishing some correlations between the parameters of the boiler and of the turbine is done usually based on mathematical models. In this paper it is determined from experimental point of view, the effectiveness of a heat recovery boiler, which operates together with a gas turbine power plant. Starting from the scheme for framing the measurement devices, we have developed a measurement procedure of the experimental data. For experimental data processing is applied the effectiveness - number of transfer unit method. Based on these experimental data we establish correlations between the recovery boiler effectiveness and the gas turbine plant characteristics. The method can be adapted depending on the type of flow in the recovery boiler.

Effective Mass-Transfer Area in a Pilot Plant Column Equipped with Structured Packings and with Ceramic Rings

1994 ◽  
Vol 33 (3) ◽  
pp. 647-656 ◽  
Author(s):  
M. Henriques de Brito ◽  
U. von Stockar ◽  
A. Menendez Bangerter ◽  
P. Bomio ◽  
M. Laso
Keyword(s):  
Mass Transfer ◽  
Effective Mass ◽  
Pilot Plant ◽  
Structured Packings
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