Heat Recovery System Control Strategy to Meet Multiple Transient Demands

2001 ◽  
Author(s):  
H. Perez-Blanco ◽  
Paul Albright
Keyword(s):  
Control Strategy ◽  
Thermal Efficiency ◽  
Power Distribution ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Demand Curve ◽  
Control Strategies ◽  
System Control ◽  
Secondary Control ◽  
Exhaust Heat

As increasing power generation needs are met with gas turbines, it is clear that exhaust heat recovery presents a considerable opportunity to reduce operational costs and enhance thermal efficiency. Typically, a system may provide power, process heat and cooling. However, each utility may have a daily demand curve with peaks that do not necessarily coincide in time. Hence, it is necessary to devise strategies that ensure meeting the needs of each user continually while maintaining high thermal efficiencies. To study these situations, a dynamic model of a system comprising a gas turbine, a heat recovery steam generator, and absorption machine was developed. The transient response of the system was studied to determine the effects of sudden changes in demand. Two control strategies utilizing proportional integral controls were considered. The first strategy relied on operating the turbine to meet the power required by the consumer. When power demands were low and steam and cooling demands high, a secondary control strategy operated the turbine to meet the steam demands, thus maximizing the thermal efficiency of the systemThe first strategy relied on operating the turbine to meet the power required by the consumer. When power demands were low and steam and cooling demands high, a secondary control strategy operated the turbine to meet the steam demands, thus maximizing the thermal efficiency of the system. System control and stability were tested, including simulation of a power distribution network simulating resistive, capacitance and inductive loads.

Combined Heat and Power: Gas Turbine Operational Flexibility

2013 ◽  
Author(s):  
James DiCampli
Keyword(s):  
Gas Turbine ◽  
Urban Areas ◽  
Gas Turbines ◽  
Heat Recovery ◽  
National Fire Protection Association ◽  
Combined Heat And Power ◽  
Combined Cycle ◽  
Electricity Production ◽  
Exhaust Heat ◽  
Gas Fuel

Combined heat and power (CHP) is an application that utilizes the exhaust heat generated from a gas turbine and converts it into a useful energy source for heating & cooling, or additional electric generation in combined cycle configurations. Compared to simple-cycle plants with no heat recovery, CHP plants emit fewer greenhouse gasses and other emissions, while generating significantly more useful energy per unit of fuel consumed. Clean plants are easier to permit, build and operate. Because of these advantages, projections show CHP capacity is expected to double and account for 24% of global electricity production by 2030. An aeroderivative power plant has distinct advantages to meet CHP needs. These include high thermal efficiency, low cost, easy installation, proven reliability, compact design for urban areas, simple operation and maintenance, fuel flexibility, and full power generation in a very short time period. There has been extensive discussion and analyses on modifying purge requirements on cycling units for faster dispatch. The National Fire Protection Association (NFPA) has required an air purge of downstream systems prior to startup to preclude potentially flammable or explosive conditions. The auto ignition temperature of natural gas fuel is around 800°F. Experience has shown that if the exhaust duct contains sufficient concentrations of captured gas fuel, and is not purged, it can ignite immediately during light off causing extensive damage to downstream equipment. The NFPA Boiler and Combustion Systems Hazards Code Committee have developed new procedures to safely provide for a fast-start capability. The change in the code was issued in the 2011 Edition of NFPA 85 and titled the Combustion Turbine Purge Credit. For a cycling plant and hot start conditions, implementation of purge credit can reduce normal start-to-load by 15–30 minutes. Part of the time saving is the reduction of the purge time itself, and the rest is faster ramp rates due to a higher initial temperature and pressure in the heat recovery steam generator (HRSG). This paper details the technical analysis and implementation of the NFPA purge credit recommendations on GE Power and Water aeroderivative gas turbines. This includes the hardware changes, triple block and double vent valve system (or drain for liquid fuels), and software changes that include monitoring and alarms managed by the control system.

scholarly journals Thermodynamic Analysis of Supercritical Carbon Dioxide Cycle for Internal Combustion Engine Waste Heat Recovery

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 216 ◽  
Author(s):  
Wan Yu ◽  
Qichao Gong ◽  
Dan Gao ◽  
Gang Wang ◽  
Huashan Su ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Thermal Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Combustion Engine ◽  
Recovery Ratio ◽  
Split Flow ◽  
Exhaust Heat ◽  
Exhaust Heat Recovery

Waste heat recovery of the internal combustion engine (ICE) has attracted much attention, and the supercritical carbon dioxide (S-CO2) cycle was considered as a promising technology. In this paper, a comparison of four S-CO2 cycles for waste heat recovery from the ICE was presented. Improving the exhaust heat recovery ratio and cycle thermal efficiency were significant to the net output power. A discussion about four different cycles with different design parameters was conducted, along with a thermodynamic performance. The results showed that choosing an appropriate inlet pressure of the compressor could achieve the maximum exhaust heat recovery ratio, and the pressure increased with the rising of the turbine inlet pressure and compressor inlet temperature. The maximum exhaust heat recovery ratio for recuperation and pre-compression of the S-CO2 cycle were achieved at 7.65 Mpa and 5.8 MPa, respectively. For the split-flow recompression cycle, thermal efficiency first increased with the increasing of the split ratio (SR), then decreased with a further increase of the SR, but the exhaust heat recovery ratio showed a sustained downward trend with the increase of the SR. For the split-flow expansion cycle, the optimal SR was 0.43 when the thermal efficiency and exhaust heat recovery ratio achieved the maximum. The highest recovery ratio was 24.75% for the split-flow expansion cycle when the total output power, which is the sum of the ICE power output and turbine mechanical power output, increased 15.3%. The thermal performance of the split-flow expansion cycle was the best compared to the other three cycles.

Comparison of Control Strategies for DSTATCOM in Power Distribution System

2011 ◽  
Vol 12 (3) ◽  
Author(s):  
Koteswara Rao Uyyuru ◽  
Mahesh Kumar Mishra
Keyword(s):  
Power Factor ◽  
Control Strategy ◽  
Power Distribution ◽  
Distribution System ◽  
Control Strategies ◽  
Harmonic Distortion ◽  
Unity Power Factor ◽  
Power Distribution System ◽  
Harmonic Cancellation ◽  
Harmonic Resonance

In this paper, the perfect harmonic cancellation (PHC), unity power factor (UPF) control strategies of distribution static compensator (DSTATCOM) are compared along with a newly proposed control strategy. In the proposed strategy, to get the best power factor, the conductance factors for the compensated load are evaluated for a specified source current total harmonic distortion (THD) limit. The performance of this method along with perfect harmonic cancellation (PHC) and unity power factor (UPF) strategies is evaluated on a distribution system model developed using PSCAD 4.2.1. In the distribution system, harmonic resonance is one of the prime factors for the harmonic propagation. Hence, in damping the harmonic resonance, selection of an appropriate control strategy for the DSTATCOM is crucial and this is verified with a detailed study. The simulation results are presented to show the performance of these strategies in load compensation and damping the harmonic propagation in the distribution system.

Waste Heat Recovery in LNG Liquefaction Plants

2015 ◽  
Author(s):  
P. Pillai ◽  
C. Meher-Homji ◽  
F. Meher-Homji
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Combined Cycle ◽  
Capital Outlay ◽  
Fuel Gas ◽  
Lng Liquefaction ◽  
The Impact

High thermal efficiency of LNG liquefaction plants is of importance in order to minimize feed usage and to reduce CO2 emissions. The need for high efficiency becomes important in gas constrained situations where savings in fuel auto consumption of the plant for liquefaction chilling and power generation can be converted into LNG production and also from the standpoint of CO2 reduction. This paper will provide a comprehensive overview of waste heat recovery approaches in LNG Liquefaction facilities as a measure to boost thermal efficiency and reduce fuel auto-consumption. The paper will cover types of heating media, the need and use of heat for process applications, the use of hot oil, steam and water for process applications and direct recovery of waste heat. Cogeneration and combined cycle approaches for LNG liquefaction will also be presented along with thermal designs. Parametric studies and cycle studies relating to waste heat recovery from gas turbines used in LNG liquefaction plants will be provided. The economic viability of waste heat recovery and the extent to which heat integration is deployed will depend on the magnitude of the accrual of operating cost savings, and their ability to counteract the initial capital outlay. Savings can be in the form of reduced fuel gas costs and reduced carbon dioxide taxes. Ultimately the impact of these savings will depend on the owner’s measurement of the value of fuel gas; whether fuel usage is accounted for as lost feed or lost product. The negative impacts include the reduction in nitrogen rejection that occurs with reduced fuel gas usage and the power restrictions imposed on gas turbine drivers due to the increased exhaust system back-pressure caused by the presence of the WHRU. When steam systems are acceptable, a cogeneration type liquefaction facility can be attractive. In addition to steam generation and hot oil heating, newer concepts such as the use of ORCs or supercritical CO2 cycles will also be addressed.

Acoustic Behavior of Exhaust Heat Recovery Systems for Gas Turbines

1973 ◽  
Author(s):  
Marv Weiss
Keyword(s):  
Gas Turbines ◽  
Heat Recovery ◽  
Empirical Method ◽  
Acoustic Energy ◽  
Exhaust Heat ◽  
Exhaust Noise ◽  
Gas Turbine Exhaust ◽  
Semi Empirical ◽  
Exhaust Heat Recovery ◽  
Turbine Exhaust

Gas turbine exhaust heat recovery systems have demonstrated the ability to attenuate acoustic energy without the benefit of sound absorbing materials. This paper describes the mechanisms utilized by heat recovery steam generators (HRSG) and by regenerators to reduce exhaust noise. Included is a semi-empirical method by which the attenuation of an HRSG can be predicted. Attenuations exhibited by the heat recovery equipment are in excess of 10 dB.

Low Emission LNG Fuelled Ships for Environmental Friendly Operations in Arctic Areas

2013 ◽  
Author(s):  
Vilmar Æsøy ◽  
Dag Stenersen
Keyword(s):  
Natural Gas ◽  
Thermal Efficiency ◽  
Distribution System ◽  
Heat Recovery ◽  
Alternative Fuels ◽  
Waste Heat ◽  
Global Perspective ◽  
Emission Reductions ◽  
Promising Alternative ◽  
Exhaust Heat

Environmental restrictions now favor cleaner fuels, and Natural gas (LNG) is one of the most promising alternative fuels. Highly efficient natural gas fuelled engines have been developed since around 1990. These engines are now entering maritime applications, offering significant emission reductions, both in a local and global perspective. Using LNG as fuel reduce NOx emissions by up to 90%, SOx and particulate matter (soot) are reduced by 95–100% and CO2 emissions are reduced by up to 25%, when compared to traditional marine fuels. These emission reductions are significant contribution especially in local and regional environments. Using LNG as a clean fuel also offers a significant increase in total energy efficiency. Combining power and heat generation, natural gas fuelled engines for on-shore power generation offer a total thermal efficiency of 80–90%, depending on the waste heat recovery rate. For liquid fuels exhaust heat recovery is limited due to the sulfur content, which may cause acid corrosion. Onboard ships, LNG fuelled engines have potential to utilize waste heat to obtain significant higher thermal efficiency than their diesel engine counterpart. LNG is mainly available from fossil sources, but now also increasingly from renewable sources as bio-gas. For storing and transportation LNG is preferred as less challenging compared to high pressure CNG. On the coast of Norway a LNG distribution system is now being built, supplying a fleet of more than 40 ships. LNG is transported by special designed small LNG carriers from the production plants to a series of main terminals along the coastline. From these main terminals the LNG is distributed by trucks to the local fuelling stations, or for direct fuelling of the ships. This paper will present the basic technology and experiences from this full scale LNG fuel system. The paper will discuss local and global environmental benefits, technical solutions, safety issues, and costs issues related to the distribution system and the on-board fuel installations.

Real-time expert system control of anaerobic digestion

1994 ◽  
Vol 30 (12) ◽  
pp. 21-29 ◽  
Author(s):  
D. P. Chynoweth ◽  
S. A. Svoronos ◽  
G. Lyberatos ◽  
J. L. Harman ◽  
P. Pullammanappallil ◽  
...  
Keyword(s):  
Expert System ◽  
Control Strategy ◽  
Control Strategies ◽  
System Control ◽  
Potential Contribution ◽  
Adaptive Optimization ◽  
Line Measurement ◽  
On Line ◽  
Methane Production Rate ◽  
Abnormal Performance

The objective of this research was to develop on-line measurement and feed-back control strategies for evaluation and optimization of a glucose-fed CSTR digester. Using methane yield as a direct on-line measurement, a model and algorithm were developed and applied for feed-back control and adaptive optimization of the digester for temperature. The model and algorithm were modified and integrated into an expert system to use methane production rate and dilution rate to automatically detect and recover digester abnormal performance resulting from underloading, overloading, and addition of an inhibitor (phenol). On-line fluorometric measurement of NADH, which is a measurement of overall microbial activity, was evaluated for its potential contribution to this control strategy.

Augmentation of Gas Turbine Power Output by Steam Injection

2001 ◽  
Author(s):  
August C. Fischer ◽  
Hans Ulrich Frutschi ◽  
Hermann Haselbacher
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Power Output ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Steam Injection ◽  
Simultaneous Increase ◽  
Exhaust Heat ◽  
Entire Amount ◽  
The Impact

Steam injection into the combustion chambers of gas turbines (GT) increases their power output. Additionally, the thermal efficiency can be raised, if steam is generated by exhaust heat. The types of steam injected gas turbines (STIG) are distinguished according to the kind of limit to the amount of steam that can be injected. A gas turbine is called partial STIG, if it cannot utilize the total amount of steam that could be generated by the gas turbine exhaust heat. The limit is given by the flow capacity of the turbine. If, on the other hand, the gas turbine is sized such that the entire amount of steam producible can be utilized, it is called full STIG. Three different partial STIG cooling models were selected to analyze the power output, the efficiency and the impact on two important components. Since the differences in the results for the three cycles are marginal, the following conclusion can be briefly summarized: Compressor surge turned out to be the strongest limit for overloading the gas turbine. At the point of maximum overload — where safe operation is still guaranteed — the steam mass flow amounts to one tenth of the nominal compressor air mass flow. At this operating point, the power output can be raised by more than 30% with a simultaneous increase in efficiency. Based on the gas turbine configurations used for the partial STIGs, the preliminary designs of two full STIG cycles have been developed. However, for full STIG operation by injection of the total amount of steam producible, either the compressor or the turbines of the original gas turbine have to be modified. In this case, the steam flow exceeding that required for cooling has to be injected into the compressed air in front of the combustor. Depending on whether the compressor is scaled down or the turbines are scaled up, the power output of full STIGs is 30 to 135% higher than that of the original gas turbine. The gross thermal efficiency is about 50.5.%.

scholarly journals Design of Gas Turbine Exhaust Heat Recovery Boiler Systems

1984 ◽  
Author(s):  
V. L. Eriksen ◽  
J. M. Froemming ◽  
M. R. Carroll
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Performance Criteria ◽  
Exhaust Heat ◽  
Recovery Boilers ◽  
Gas Turbine Exhaust ◽  
The Impact ◽  
Exhaust Heat Recovery ◽  
Turbine Exhaust

Heat recovery boilers utilizing the exhaust from gas turbines continue to be viable as industrial cogeneration systems. This paper outlines the types of heat recovery boilers available for use with gas turbines (1–100 MW). It discusses the design and performance criteria for both unfired and supplementary fired gas turbine exhaust heat recovery boilers of single and multiple pressure levels. Equations to assist in energy balances are included along with design features of heat recovery system components. The economic incentive to achieve the maximum practical heat recovery versus the impact on boiler design and capital cost are examined and discussed. It is intended that the information presented in this paper will be of use to individuals who are not intimately familiar with gas turbine heat recovery systems so that they can better specify and evaluate potential systems.

scholarly journals Gas Turbine Exhaust Heat Recovery by Hybrid Steam/Ternary Aqueous Immiscible Liquid Cycle

1984 ◽  
Author(s):  
B. M. Burnside
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Immiscible Liquid ◽  
Working Fluid ◽  
Exhaust Temperature ◽  
Boiling Points ◽  
Exhaust Heat ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

The concept of the dual pressure steam/pure organic hybrid immiscible liquid cycle applied to recover exhaust heat from gas turbines is extended to include organic mixtures. Thermodynamics of the resulting ternary working fluid cycle is presented. For the cycle arrangement analysed it is calculated that the ternary steam/nonane/decane cycle with the organic very nonane rich produces about 2% more work than the corresponding all steam cycle for a typical gas turbine exhaust temperature. It is estimated that this advantage can be raised to about 4% by adding additional heaters at the stack end of the heat recovery generator. The analysis shows that it is unnecessary to use a pure alkane organic. A mixture containing up to about 5% of alkanes with higher boiling points than nonane is adequate.

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