Performance degradation analysis of a medium pressure superheater due to tube deactivation (original) (raw)

Failure analysis and retrofitting of superheater tubes in utility boiler

The extreme spray water mass flow rate deviation was observed to occur in the middle temperature superheater of Sahand 2 Â 325 MW Power Plant utility boiler, which severely affected its economic performance and safe operation. Boilers operating in these conditions led to failure in superheater tubes at the same place for two consecutive times in a three year span. Thus, the failure analysis of superheater tubes by investigating the visual inspection, chemical, scale and creep analysis was carried out. The brittle failure occurred in the superheater tubes after the fuel was changed from natural gas to heavy oil. Failure analysis showed that tubes were suffering from long term overheating which was instigated by high spray water flow rate. In order to rectify the boiler operating conditions, some modifications were applied in the boiler unit 1 and operating parameters on this boiler were compared with boiler unit 2. The results showed that the 8.33% reduction in heating surface area corresponds to 52.84 and 17.80% reduction in spray water mass flow rate for capacities equal to 300 and 260 MW, respectively.

Steam system optimization of an industrial heat and power plant

Thermal Science, 2020

Improvement of the energy conversion processes efficiency helps to achieve a more reliable energy supply, a cleaner environment, more competitive businesses, and higher living standard. Industry data indicate significant potential for improving the efficiency of steam systems and minimizing their operating costs by implementing various measures. The present work is a result of a systematic approach for energy performance analysis and identification of opportunities for optimizing the steam-condensate system of the combined heat and power plant ESM Energetika, Skopje, North Macedonia. The boiler plants provide superheated steam used in a hot-water station for the district heating system, for electricity generation, and as process steam for industrial customers. As the main operating costs of the plant stem from the natural gas consumption, the implementation of a set of energy efficiency measures will lead to its reduction, accompanied by less environmental impact. As a result of the...

PERFORMANCE ANALYSIS OF A STEAM POWER PLANT OPERATING UNDER SUPERHEATED AND ISENTROPIC CONDITIONS

Quality and sufficient power distribution at the present is a major challenge in many cities and industrial locations in most developing countries, like Nigeria. This is as a result of many factors which include inadequate generation and obsolete equipment. This research work entitled Performance Analysis of a Steam Power Plant Operating under Superheated and Isentropic Conditions, was undertaken to evaluate the variables that will bring about the efficient running of a typical steam power plant. With a turbine pressures of 20 bar and 2 bar, the analysis yielded a specific work output of 854.65 kJ/Kg; and plant thermal efficiency of 26.08 %. The rate of heat loss by the condenser approximates to 4114.55 J/s; and the rate of heat generation by the boiler equals 5027.74 J/s. The condition of steam at points 4 and 6 s is wet, but superheated at points 3 and 5. Optimizing the values of enthalpies at points 3 and 5, will improve the thermal efficiency of the plant. These factors, if augmented, will heighten the power output capacity of any steam thermal system.

Thermal Analysis of Superheater Platen Tubesin Boilers

Superheaters are among the most important components of boilers and have major importance due to this operation in high temperatures and pressures. Turbines are sensitive to the fluctuation of superheaterstemperature;therefore even the slightest fluctuation in the outlet vapor temperature from the superheaters does damage the turbine axis and fins. Examining the potential damages of combustion in the boilers and components such as the superheaters can have a vital contribution to the progression of the productivity of boiler, turbine and the power plant altogether it solutions are to be fund to improve such systems. In this study, the focus is on the nearest tube set of superheaters to the combustion chamber.These types of tubes are exposed to a wide range ofcombustion flames such that the most heat transfer to them is radiation type.Here, the 320 MW boiler of Isfahan power plant (Iran), the combustion chamber, 16 burners and the platensuperheater tubes were remodeled by CFD technique. The fluid motion, the heat transfer and combustion processes are analyzed. The two-equation turbulence model of k-εis adopted to measure the eddy viscosity. The eddy dissipation model is used to calculate the combustion as well as the P-1 radiation model to quantify the radiation. The overheated zones of superheater tubes and the combustion chamber are identified in order toimprove this problem by applying the radiation thermal shields and knees with porous crust which are introduced as the new techniques.

Steam Power Plant Performance Operating at High Temperature and Pressure Conditions

International Research Journal of Innovations in Engineering and Technology

Steam power plants have been used for generating electric power since early 20 century; their cycles have been subjected to extensive studies in order to improve their performance including power output, thermal efficiency and specific steam consumption etc. The aim of this work is to examine several configurations based on Rankin cycle to obtain optimum cycle performance. However, four different configurations have been studied including simple Rankine cycle, Ideal regenerative Rankine cycle, Ideal regenerative-reheat cycle and finally regenerativereheat cycle with intermediate steam extraction for high pressure turbine. Two cases have been considered in current study; the first case was carried out when the turbine pressure is assumed to be constant at 80 bar and the temperature varies from 300°C to 700°C. The second case was studied when turbine inlet pressure varies from 35 to 120 bars and the temperature of steam entering turbine is kept constant at 480 °C. Regarding to the first case, the obtained results reflects that the configuration of regenerativereheat with intermediate steam extraction has a better performances which involve high thermal efficiency, low specific steam consumption, and very high work ratio. Results show that thermal efficiency increases nearly by (4.77 %), while the specific steam consumption reduced nearly by (10.22%), and finally work ratio improved nearly by (0.08%) in comparison with simple cycle, when inlet turbine temperature increase from 300 to 700 °C. However, in the second case, the turbine inlet pressure increases from 35 to 120 bar (temperature of superheated steam is 480°C). Results show the thermal efficiency increase nearly by (2.42 %), Specific steam consumption improved nearly by (7.65%), and finally work ratio decreased nearly by (0.12%).

Reducing steam transport pipe temperatures in power plants

Energy, 2019

A cycle analysis has been applied to a model of a advanced ultra-supercritical steam plant with novel steam pipes. The transfer pipes proposed incorporate internal thermal coatings and are externally jacketed to enable cooling. This enables higher temperature working steam, while keeping the pipe wall temperature below the acceptable limit for more conventional steel alloys and avoiding the need to use higher cost austenitic stainless steels and nickel base alloys. The baseline design had a superheat temperature of 700 • C and a reheat temperature of 720 • C. A thermal coating thickness of 2.8 mm is sufficient to keep the wall temperatures of the steam transfer pipe after the supercritical boiler below 600 • C. For the transfer pipe located after the reheater a thicker coating or less ambitious reheat temperature is required to achieve acceptable pipe wall temperatures. Whereas subcritical plant has a calculated cycle efficiency of 42.1%, the elevated temperature and pressure in a customary ultra-supercritical steam boost cycle efficiency to 52.2%. Modifying this design with a thermal barrier lowers the cycle efficiency to 51.4%, still appreciably better than for subcritical plant. Alternative plant cooling arrangements might improve pipe temperatures but have minimal impact on overall cycle efficiency.

Investigating The Performance of A Steam Power Plant

ABSTRACT: The performance analysis of Shobra El-Khima power plant in Cairo, Egypt is presented based on energy and exergy analysis to determine the causes , the sites with high exergy destruction , losses and the possibilities of improving the plant performance. The performance of the plant was evaluated at different loads (Full, 75% and, 50 %). The calculated thermal efficiency based on the heat added to the steam was found to be 41.9 %, 41.7 %, 43.9% , while the exergetic efficiency of the power cycle was found to be 44.8%, 45.5% and 48.8% at max, 75% and, 50 % load respectively. The condenser was found to have the largest energy losses where (54.3%, 55.1% and 56.3% at max, 75% and, 50 % load respectively) of the added energy to the steam is lost to the environment. The maximum exergy destruction was found to be in the turbine where the percentage of the exergy destruction was found to be (42%, 59% and 46.1% at max, 75% and, 50 % load respectively). The pump was found to have the minimum exergy destruction. It was also found that the exergy destruction in feed water heaters and in the condenser together represents the maximum exergy destruction in the plant (about 52%). This means that the irreversibilities in the heat transfer devices in the plant have a significant role on the exergy destruction. So, it is thought that the improvement in the power plant will be limited due to the heat transfer devices.

Performance impacts on steam cycle, unit heat rate and output of a Thermal Generating Unit

The heat exchangers, particularly in the regenerative cycle of a coal based unit are of utmost importance for an optimally economized operation of the power plants. Thus, these heat exchangers like, LP/HP heater, deaerator, Re-heater, superheaters, and condenser etc. are warranted to be operated at designed parameters to achieve optimal performance not of their own only, but also for the entire integrated system of the cycle of power plant unit. Thus, potential of heat exchanger networking need to be realized to its maximum capacity.

Thermal Analysis of Steam Turbine Power Plants.pdf

Steam are a major energy consumer. Optimising process operating conditions can considerably improve turbine water rate, which in turn will significantly reduce energy requirement. Various operating parameters affect condensing and back pressure turbine steam consumption and efficiency. The industrial sector is the largest energy consumer, accounting for about 30 % of total energy used. Fuel and energy prices are continuously rising. With the present trend of energy prices and scarcity of hydrocarbon resources lowering energy requirement is a top priority. Energy conservation benefits depend on the adopting minor or major modifications and using the latest technology. Turbines are designed for a particular operating conditions like steam inlet pressure, steam inlet temperature and turbine exhaust pressure/ exhaust vacuum, which affects the performance of the turbines in a significant way. Variations in these parameters affects the steam consumption in the turbines and also the turbine efficiency. The present study was done to improve the power output of the turbine, thermal efficiency and specific steam consumption in conventional steam power plants. Three cycles i.e regenerative cycle, superheater cycle and cogeneration cycle are considered to formulate the data and obtain a better result in steam turbine power plants.

Analysis of superheater tubes degradation at a tangentially fired pulverized coal power plant

THE 4TH BIOMEDICAL ENGINEERING’S RECENT PROGRESS IN BIOMATERIALS, DRUGS DEVELOPMENT, HEALTH, AND MEDICAL DEVICES: Proceedings of the International Symposium of Biomedical Engineering (ISBE) 2019

Thinning of boiler tubing is one of common failure mechanism of coal-based boiler unit. An ultrasonic thickness testing (UT) is typically used to determine the state of boiler tube thickness and is done during a yearly overhaul. The usefulness of thickness data can be problematic due to some fluctuation and irregularities in the data. In the present work, UT data from 4 years inspection will be analyzed with the aim to understand the fundamental mechanism for thinning of the superheater tube. Some part of the UT data is analyzed to obtain the thinning rate of the superheater tube. The thinning trend is the basis for predicting the value of thickness and compared with actual measurement values. The predicted and actual values were tested with statistical operation to observe the significant difference between both values and also the quality of prediction.