Economy of Efficient Air Preheating With Extraction Steam

1962 ◽  
Vol 84 (1) ◽  
pp. 1-6
Author(s):  
M. K. Drewry
Keyword(s):  
Flue Gas ◽  
Heat Rate ◽  
Heat Rejection ◽  
Air Heater ◽  
Fixed Charges ◽  
Rate Improvement

Two per cent heat rate improvement of a 275,000 kw unit results from efficient 2-stage steam air preheaters heating to 190 F with 5 F terminal temperature differences. Condenser heat rejection and turbine leaving losses are reduced substantially. Flue-gas losses are not increased. Air heater cleanliness is improved. Maintenance is reduced. Annual coal savings after fixed charges are one half of the net added investment.

A Modified Master Cycle Off-Design Performance and Heat Rate Improvement Optimization

2017 ◽  
Author(s):  
Chenghao Fan ◽  
Dongsheng Pei ◽  
Xiang He ◽  
Wentai Zhou ◽  
Zengtao Wei
Keyword(s):  
Power Generation ◽  
Thermodynamic Simulation ◽  
Heat Rate ◽  
Feed Water ◽  
Partial Load ◽  
Current Cycle ◽  
Rate Improvement ◽  
Pressure Extraction ◽  
Rate Optimization ◽  
Future Work

Coal-fired power generation will continue to be the cornerstone of China’s energy sources in the coming decades and advanced ultra-supercritical technology is the future of coal-fired power generation. This paper selects double reheat cycle design for study and incorporates back pressure extraction steam turbine (BEST) into current cycle design, which used to drive boiler feed water pump and feed regenerative heaters. This design prevailed in US in 1960s and gradually was replaced by condensing turbine due to less efficiency benefits at subcritical steam condition. Reinvention of BEST design in current double reheat cycle is an evitable choice, because the efficiency advantage is improved at USC steam condition. BEST configuration incorporated into current double reheat cycle and advanced cycle is developed to compare with other two conventional systems in this study. Thermodynamic simulation at design and off-design condition shows that BEST configuration has an obvious efficiency advantage at design load, but the advantage decreases at partial load. BEST expansion line and reheat pressure is integrated in cycle heat rate optimization. Genetic algorithm is chosen to implement the optimization and exergy analysis method is utilized to evaluate BEST expansion line optimization results. Finally, BEST design limitation and future work is practically concluded.

Applying the X-Ratio Correction to Calculated Air Heater Efficiency: An Alternate Method

2010 ◽  
Author(s):  
David C. McLaughlin ◽  
Joseph R. Nasal
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Correction Factor ◽  
Mass Flow ◽  
Flue Gas ◽  
Correction Method ◽  
Gas Temperature ◽  
Original Design ◽  
Air Heater ◽  
The Impact

ASME PTC 4.3 on testing Air Heaters provides guidance for the calculation of gas-side efficiency as a measure of air heater performance. This code also provides for calculation of air heater X-ratio (XR), which is the ratio of the heat capacity (mass flow times specific heat capacity) of the air flowing through the heater to that of the flue gas. The code acknowledges the impact of XR on air heater efficiency, and dictates that the gas temperature leaving the air heater (and hence, air heater efficiency) be corrected for deviation from design XR by the use of “appropriate design correction curves” [1]. Unfortunately, such curves are rare, and therefore this important correction is usually ignored in routine air heater test calculations by power plant testing personnel, resulting in an incorrect calculation of air heater efficiency. This is particularly true for balanced draft boilers burning coal that are aged and have a significant amount of air leakage into the boiler setting. On these boilers, the ratio of combustion flue gas mass flow to combustion air mass flow is changed significantly from the original design, and therefore applying an XR correction factor is essential to calculating and reporting accurate air heater efficiency. This paper presents a method to calculate and correct for a deviation from design X-ratio based on standard heat exchanger analysis techniques, namely the ε-NTU method, which utilizes the concept of heat exchanger effectiveness (ε). A solution that results in applying the ratio of the design to actual XR’s as the correction factor is developed. The paper also provides empirical data from testing on a coal-fired boiler to validate the alternate correction method.

Energetic and Environmental Analysis of Partial Repowering of a Coal Fired Power Plant Through Upstream GT Integration and Employing Waste Heated Feed Water Heaters

2014 ◽  
Author(s):  
S. Samanta ◽  
S. Ghosh
Keyword(s):  
Power Plant ◽  
Flue Gas ◽  
Coming Out ◽  
Heat Rate ◽  
Forced Flow ◽  
Feed Water ◽  
Air Preheater ◽  
Water Heaters ◽  
Heat Loads ◽  
Consequent Increase

This paper presents a theoretical study of partial repowering scheme for an existing 210MW coal fired power plant and reports predicted performance improvement obtainable from the repowering by using Cycle Tempo software. In this method old boiler is used as it is, only modifying its air heater and forced flow sections. Out of four operating coal mills, one mill is considered to be taken out. A new natural gas fired gas turbine (GT) block is considered to be integrated with the existing plant whose exhaust is fed to the existing boiler. The GT size is selected such that its exhaust provide heat input equivalent to the replaced coal mill. The burners associated with that coal mill are assumed to be modified to handle hot exhaust gas from the GT block. It is noticed that a substantial amount of energy is available in the flue gas, coming out from the boiler, after the air preheater which can partially meet the heat loads of feed water heaters. This helps in saving of intermediate pressure (IP) and low pressure (LP) bleed steam and consequent increase in the output of the steam cycle. The partial repowering results in nearly 40% increase in capacity of the plant (from 210MW to 284MW). It also results in substantial increase in overall efficiency of the repowered plant by 28%, and consequent decrease in plant heat rate by 22%. The specific CO2 emission of the plant decreases about 31% after repowering.

Low DP FlameSheet™ Extended Validation of a Flexible, Low Emissions, Higher Output and Efficiency F-Class Turbine Upgrade

2020 ◽  
Author(s):  
Hany Rizkalla ◽  
Timothy Hui ◽  
Fred Hernandez ◽  
Matthew Yaquinto ◽  
Ramesh KeshavaBhattu
Keyword(s):  
Gas Turbine ◽  
Shale Gas ◽  
Power Plants ◽  
Heat Rate ◽  
Combined Cycle ◽  
Energy Market ◽  
Heavy Duty ◽  
Ambient Conditions ◽  
Rate Improvement ◽  
Combustion Systems

Abstract Renewables proliferation in the energy market is driving the need for flexibility in gas fired power plants to enable a wider and emissions compliant operability range. The ability for a gas fired plant to peak fire while maintaining emissions compliance, full life interval capability, improved simple and combined cycle heat rate and the ability to achieve extended turndown, positions a gas fired asset to benefit from an improved capacity factor, and overall economic viability in an increasingly renewables’ dependent energy market. The low pressure drop FlameSheet™ combustor variant’s implementation alongside PSM’s Gas Turbine Optimization Package (GTOP3.1) on a commercially operating frame 7FA heavy duty gas turbine in 2018 and as introduced in GT2019-91647, is presented with emphasis on extended validation of operational and emissions/tuning performance at different ambient conditions, higher peak firing and minimum load after one year of continuous commercial operation. The output and heat rate improvement achieved with the FlameSheet™/GTOP3.1 conversion thus enabling improved capacity is also discussed. As shale gas continue to grow as a dominant source of the U.S Natural gas supply, the need for fuel flexible combustion systems enabling tolerance to higher ethane/ethylene concentrations associated with Shale gas is required for improved operability. The adverse impact and means to mitigate such higher ethane/ethylene content on standard F-Class heavy duty combustion systems is also presented as part of said FlameSheet™/GTOP 3.1 conversion.

Improving Combined Cycle Part Load Performance by Using Exhaust Gas Recirculation Through an Ejector

2021 ◽  
Author(s):  
Majed Sammak ◽  
Chi Ho ◽  
Alaaeldin Dawood ◽  
Abdurrahman Khalidi
Keyword(s):  
Gas Turbine ◽  
Heat Rate ◽  
Heating System ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Entrainment Ratio ◽  
Ambient Temperatures ◽  
Air Heating ◽  
Rate Improvement ◽  
Gas Recirculation

Abstract The gas turbine inlet air heating system has been used for improving the combined cycle heat rate at part load operation, which has a positive impact on the combined cycle profitability and fuel consumption. The paper objective was to introduce a new gas turbine inlet air heating system. The inlet air heating system studied in this paper was exhaust gas recirculation into inlet air compressor through an ejector. The ejector motive flow was defined as the compressor bleed air from the compressor discharge section while the ejector entrainment flow was defined as the recirculated exhaust gases from the gas turbine exhaust duct. This study was performed on generic gas turbine and combined cycle model. The selected combined cycle model was 1-on-1 (one gas turbine, one heat recovery steam generator and one steam turbine train). The heat recovery steam generator was a 3-pressure level with reheat. The combined cycle heat rate improvement at different ejector entrainment ratio varying from 0.5 to 5 with 0.5 intervals was studied. The selected ejector area ratio was set to 25 which together with the motive to suction pressure ratio gave an entrainment ratio of 2.5. The selected ejector entrainment ratio of 2.5 was aligned with the common practice design of the ejectors. The ejector motive flow was limited to 1% of compressor inlet air flow. Furthermore, the combined cycle heat rate improvement at different combined cycle loads were analysed. The analysis was performed on combined cycle loads from 90% to 40% load with a 10% interval and at the ambient temperatures 7°C, 15°C and 35°C. At the ambient temperatures 7°C, 15°C and 35°C, the combined cycle heat rate improvement was measured at loads below 80%. The combined cycle heat rate improvements proved greater at lower combined cycle loads and lower ambient temperatures. The combined cycle heat rate improvement was 0.67% at the ambient temperature 15°C and 60% combined cycle load. On the other hand, the combined cycle heat rate improvement was 1.4% at 40% combined cycle load and ambient temperature 7°C.

scholarly journals Utilizing PV System for Auxiliary Energy Demand in Conventional Power Plant

2017 ◽  
Vol 14 (2) ◽  
Keyword(s):  
Power Plant ◽  
Energy Demand ◽  
Power Plants ◽  
Combustion Engine ◽  
Heat Rate ◽  
Daily Basis ◽  
Feeding System ◽  
Pv System ◽  
Transmission Grid ◽  
Rate Improvement

The purpose of this study is to investigate the utilization of PV feeding system for auxiliary energy demand in the conventional power plants. A 573 MW tri-fuel power plant in Jordan IPP3 the largest internal combustion engine (ICE) power plant in the world is the case study to evaluate the energy economy aspects of PV feeding system and its effects on the monthly payments for this energy. All relevant computations will be performed in order to end up with reasonable, feasible and applicable results. The auxiliary energy demand of this power plant while no operation is covered from the national transmission grid which results in around 48 MWh imported energy on daily basis taking in mind no operation case. Therefore, such PV system will have a noticeable impact over the productivity of the whole plant as well as raising the money spent for fuel upon the reduction of the heat rate. The PV system is sized to have a capacity of 2 MWp planned to be utilized during the day time. Considering the imported energy benefit, the corresponding pay-back period will through the 5th year where is expected to be accomplished during the 7th year when it comes to the heat rate improvement. The prominent fact to be mentioned here that the pay-back period upon either imported energy benefit of heat rate improvement is calculated separately.

Capacity Mapping for Optimum Utilization of Pulverizers for Coal Fired Boilers

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Chittatosh Bhattacharya
Keyword(s):  
Flue Gas ◽  
Thermal Power ◽  
Heat Rate ◽  
Cost Effective ◽  
Volatile Matter ◽  
Metal Loss ◽  
Inlet Temperature ◽  
Gas Temperature ◽  
Flame Instability ◽  
Standard Output

Pulverizers play a pivotal role in coal-based thermal power generation. Improper coal fineness or drying reflects a qualitywise deterioration. This results in flame instability, unburnt combustible loss, and a propensity to slagging or clinker formation. Simultaneously, an improper air-coal ratio may result in either coal pipe choking or flame impingement, an unbalanced heat release, an excessive furnace exit gas temperature, overheating of the tube metal, etc., resulting in reduced output and excessive mill rejects. In general, the base capacity of a pulverizer is a function of coal and air quality, conditions of grinding elements, classifier, and other internals. Capacity mapping is a process of comparison of standard inputs with actual fired inputs to assess the available standard output capacity of a pulverizer. In fact, this will provide a standard guideline over the operational adjustment and maintenance requirement of the pulverizer. The base capacity is a function of grindability; fineness requirement may vary depending on the volatile matter (VM) content of the coal and the input coal size. The quantity and the inlet temperature of primary air (PA) limit the drying capacity. The base airflow requirement will change depending on the quality of raw coal and output requirement. It should be sufficient to dry pulverized coal (PC). Drying capacity is also limited by utmost PA fan power to supply air. The PA temperature is limited by air preheater (APH) inlet flue gas temperature; an increase in this will result in efficiency loss of the boiler. Besides, the higher PA inlet temperature can be attained through the economizer gas bypass, the steam coiled APH, and the partial flue gas recirculation. The PA/coal ratio, a variable quantity within the mill operating range, increases with a decrease in grindability or pulverizer output and decreases with a decrease in VM. Again, the flammability of mixture has to be monitored on explosion limit. Through calibration, the PA flow and efficiency of conveyance can be verified. The velocities of coal/air mixture to prevent fallout or to avoid erosion in the coal carrier pipe are dependent on the PC particle size distribution. Metal loss of grinding elements inversely depends on the YGP index of coal. Besides that, variations of dynamic loading and wearing of grinding elements affect the available milling capacity and percentage rejects. Therefore, capacity mapping is necessary to ensure the available pulverizer capacity to avoid overcapacity or undercapacity running of the pulverizing system, optimizing auxiliary power consumption. This will provide a guideline on the distribution of raw coal feeding in different pulverizers of a boiler to maximize system efficiency and control, resulting in a more cost effective heat rate.

Sign in / Sign up

Export Citation Format

Share Document