Supercritical Thermal Power Plant Research Articles

COMPARISON OF ENERGY FLOW STREAM AND ISENTROPIC METHOD FOR STEAM TURBINE ENERGY ANALYSIS

In this paper, a comparison of two different methods for a steam turbine energy analysis is presented. A high-pressure steam turbine from a supercritical thermal power plant (HPT) was analysed at three different turbine loads using the energy flow stream (EFS) method and isentropic (IS) method. The EFS method is based on steam turbine input and output energy flow streams and on the real steam turbine produced power. The method is highly dependable on the steam mass flow rate lost through the turbine gland seals. The IS method is based on a comparison of turbine steam expansion processes. Observed energy analysis methods cannot be directly compared because they are based on different sources of steam turbine energy losses, so, an overall steam turbine energy analysis is presented. Unlike most steam turbines from the literature, the analysed HPT did not have the highest overall energy efficiency at a full load due to exceeding the water/steam critical pressure at the turbine inlet during such operation.

Effect of Heat Treatment on Microstructure and Hot Impact Toughness of Various Zones of P91 Welded Pipes

The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.

350 MW超临界单列风机供热机组能耗分析

华能洛阳热电厂350 MW超临界供热机组采用单列布置风机，对机组能耗进行分析，将锅炉和汽机主要参数与设计值进行比较，分析相关参数，提出降低能耗方法，对主要辅机厂用电进行分析，分析降低厂用电措施，对单列风机特性进行分析，保证机组运行安全。 350 MW super critical thermal power plant of Huaneng Luoyang power plant uses a single row layout wind machine; the energy consumption of the unit was analyzed. The main parameters of boiler and steam turbine were compared with design value. The method to reduce energy con-sumption is proposed by analyzing the related parameters. The measures to reduce auxiliary power is analyzed based on the electricity of main auxiliary machine factory, and we also carry on the analysis to the characteristics of single row fan to ensure the safe operation of the unit.

Energy and exergy analysis of a super critical thermal power plant at various load conditions under constant and pure sliding pressure operation

The objective of this paper is to perform an energetic and exergetic analysis on a 660 MWe coal fired supercritical thermal power plant at 100%, 80% and 60% of normal continuous rating (NCR) conditions under constant pressure as well as pure sliding pressure operation and to highlight the benefits of the latter over the former. The energetic input, energetic output, exergetic input, exergetic output, energetic and exergetic efficiencies of various components of the supercritical thermal power plant are estimated at 660 MWe, 528 MWe and 396 MWe load under both constant pressure as well as pure sliding pressure operation. Also the energy losses and exergy destruction in various components of a power plant i.e. Boiler, high pressure turbine (HPT), intermediate pressure turbine (IPT), low pressure turbine (LPT), condenser, gland steam coolers, condensate extraction pumps, low pressure heaters (LPH), drip pumps (DP), deaerator (D), boiler feed pump (BFP) and high pressure heaters (HPH) have been calculated. The results have shown that the boiler has the maximum rate of exergy destruction than any other component in the power plant. After the boiler, turbine has the maximum rate of exergy destruction than any other component of the power plant. The study reveals that there is a significant reduction in the rate of exergy destruction at part load conditions for the turbine in case of sliding pressure operation in comparison to constant pressure operation. The rate of exergy destruction in the turbine at 100%, 80% and 60% of NCR conditions is 49.16 MW/43.22 MW/43.92 MW for constant pressure operation and 47.66 MW/37.88 MW/28.94 MW respectively. The BFP power input reduces by 9.39%, 21.52% and 42.5% respectively at 100%, 80% and 60% of NCR conditions if the unit runs in sliding pressure mode compared to constant pressure mode.

Exergetic analysis and evaluation of coal-fired supercritical thermal power plant and natural gas-fired combined cycle power plant

The present work has been undertaken for energetic and exergetic analysis of coal-fired supercritical thermal power plant and natural gas-fired combined cycle power plant. Comparative analysis has been conducted for the two contestant technologies. The key drivers of ener- getic and exergetic efficiencies have been studied for each of the major sub-system of two contestant technologies. Overall energetic and exergetic efficiency of coal-fired supercritical thermal power plant are found to be 43.48 and 42.89 %, respectively. Overall energetic and exergetic efficiency of natural gas-fired combined cycle power plant are 54.47 and 53.93 %, respectively. The major energetic power loss has been found in the condenser for coal-fired supercritical thermal power plant. On the other hand, the major energetic power loss has been found in both the condenser and heat recovery steam generator for gas-fired combined cycle thermal power plant. The exergetic anal- ysis shows that boiler field is the main source of exergetic power loss in coal-fired supercritical thermal power plant and combustion chamber in the gas-fired combined cycle thermal power plant. It is concluded that natural gas-fired combined cycle power plant is better from energetic and exergetic efficiency point of view. These results will be useful to all involved in the improvement of the design of the existing and future power plants.

Supervision and Significance on the Core Parameters for Steam and Water System in Supercritical Utility Thermal Power Plant

Several core parameters in supercritical thermal power plant were briefly outlined, which had the significance in safe and economic operation. The influence and damage of Cl-, SO42- in steam and water system were discussed, and the mathematical relationship between the cation conductivity and the concentration of Cl-, SO42- was described in room temperature. Meanwhile, the iron transport and deposition in steam and water system was analyzed, according to iron oxide solubility at different temperature and pressure.

Exergetic analysis of solar concentrator aided coal fired super critical thermal power plant (SACSCTPT)

Comparative energetic and exergetic analysis of coal-fired supercritical thermal power plant (CSCTPT) and solar concentrator aided coal fired supercritical thermal power plant (SACSCTPT) have been carried out in this article. Optical analysis of Linear Fresnel reflecting (LFR) solar concentrator is used to predict the effect of focal distance and width of reflector upon the local concentration ratio and the tilt (θ) angles that are important parameters for SACSCTPT performance studies. Energetic and exergetic analysis for evaluating the effect of concentration ratio and inlet temperature of the fluid on LFR solar concentrator are carried out. An instantaneous increase in power generation capacity of about 20 % is observed by substituting turbine bleed streams to all the low pressure and high pressure feed water heaters of CSCTPT with solar concentrator aided feed water heaters (SAFWH). Coal consumption is increased by 3.35 % for reheat of the steam by substitution of high pressure feed water heaters with SAFWH. Energetic efficiencies of SACSCTPT appear high as compared to the solar alone thermal power plant and low as compared to coal-fired super critical thermal power plants. Furthermore, for a SAFWH, it is found that the land area requirement is 4.78 ha/MW.

Boiler parametric study to decrease irreversibility

In this paper, the useful concept of energy and exergy utilization is analyzed, and applied to the boiler system. Energy and exergy flows in a boiler have been shown in this paper. The energy and exergy efficiencies have been determined as well. In a boiler, the energy and exergy efficiencies are found to be 89.21% and 45.48%, respectively. A boiler energy and exergy efficiencies are compared with others work as well. It has been found that the combustion chamber is the major contributor for exergy destruction followed by heat exchanger of a boiler system. Furthermore, Modifications are examined to increase gas-fired steam power plant efficiency by reducing irreversibilities in the steam generator, including Decreasing the fraction of excess combustion air, and/or the stack-gas temperature. Overall-plant energy and exergy efficiencies both increase by 0.19%, 0.37% respectively when the fraction of excess combustion air decreases from 0.4 to 0.15, and by 0.84%, 2.3% when the stack-gas temperature decreases from 137°C to 90°C Keywords. Exergy efficiency, energy efficiency, super critical thermal power plant, excess air, stack gas temperature

(Re) Evolution in HR Strategies - Power Sector

Evolution or a revolution in HR Strategies is required in the vibrant and expanding Powerful Sector. The power Sector in India has gone in for reforms unbundling the sector into separate accountable entities. The Power Sector conventionally revolves around Power Generation, Transmission and Distribution. The Manufacturing (or Sourcing from Manufacturers) and Project Development is as much important from the developers’ perspective. Each of these activities requires specialized skill sets. In this paper, emphasis has been placed on Supercritical Thermal Power Plants. The HR Managers, if are passive are just to pass on the job description to HR Consultant, but the active ones will get involved with the process of Placement and or pre-placement training for having a human resource added to the organization. Some of the organizations in any of the above activities of the Power Sector are even considering HR department as a profit center. As a business transformation of the Power Sector organization, the HR Skill center goes on developing number of personnel, the best ones are picked up by their own organization, and the others are made available to the sub-contractors or other organizations. In both cases HR Skill center acts as a placement company specializing in Power Sector. While Power sector needs skilled manpower at home, there is an acute shortage to run the Power Plants abroad. Power Sector personnel are getting re-employed to meet the partial shortage. The Skills mismatch and skill gaps are being now heard in every sector and Power Sector is not different. This is more acute in Europe where the work force is becoming grey. Even China is on the edge to suffer because of One Child Policy. New business models like Cross Culture Joint Ventures (JVs), Public Private Partnership (PPP) involve a lot of vibrations in complete HR Chain.

Simulation Research of the Condenser in a 600MW Supercritical Thermal Power Plant

A simulation model of the condenser in a 600MW supercritical thermal power plant was developed by using Matlab/Simulink. The important parameters such as condenser pressure, hot well water temperature and cooling water temperature were calculated by using this model. The simulation results under different operating conditions were compared with design parameters, and the relative errors were within -0.2% and +0.2%. This shows that the simulation model developed in this paper is reasonable. The dynamic performance and off-design performance of the condenser were studied by using the simulation model, which would be useful for the optimal operation of the condenser. The model of the condenser, which was developed based on the modular modeling method, would be an important basis for the simulation of the whole power plant.

Damage assessment method of P91 steel welded tube under internal pressure creep based on void growth simulation

Development of creep damage assessment methods for longitudinal welded piping of P91 steel is important and an urgent subject to maintain reliable operation of boilers in ultra super critical thermal power plants. Internal pressure creep tests were conducted on P91 steel longitudinal welded tubes to characterize the evolution of creep damage in a heat-affected zone (HAZ) of the longitudinal welded pipe. Failure occurred at a heat-affected zone without significant macroscopic deformation. It was found that initiation of creep voids had concentrated at mid-thickness region rather than surface. Three-dimensional finite element (FE) creep analysis of the creep tested specimens was conducted to identify stress and creep strain distribution within the specimen during creep. Finite element creep analysis results indicated that triaxial tensile stress yielded at the mid-thickness region of the HAZ. It was suggested that the triaxial stress state caused acceleration of the creep damage evolution in the heat-affected zone resulting in internal failure of the tube specimens. Void growth behavior in the heat-affected zone was well predicted with the previously proposed void growth simulation method by introducing void initiation function to the method. A “limited strain” was defined as rupture criterion and dependency of the maximum stress and multiaxiality on the “limited strain” was derived by the void growth simulation. Creep damage distribution in the HAZ under the internal creep test was calculated by proposed damage assessment method.

Influence of Laser Power on the Hardening of Ti6Al4V Low-Pressure Steam Turbine Blade Material for Enhancing Water Droplet Erosion Resistance

To overcome water droplet erosion of Ti6Al4V alloy blade material used in low-pressure steam turbine (LPST) of high-rating nuclear and super critical thermal power plants, high-power diode laser (HPDL) surface treatment at two temperatures corresponding to two different power levels was carried out. During incubation as well as under prolonged erosion testing, the HPDL surface treatment of this alloy has enhanced its resistance significantly. This is due to the formation of fine-grained martensitic (ά) phase due to rapid heating and cooling associated with laser treatment. The droplet erosion test results after HPDL surface treatment on this alloy, SEM, XRD analysis, and residual stresses developed due to HPDL surface treatment are given in this paper.

Enhanced Droplet Erosion Resistance of Laser Treated Nano Structured TWAS and Plasma Ion Nitro-Carburized Coatings for High Rating Steam Turbine Components

This article deals with surface modification of twin wire arc sprayed (TWAS) and plasma ion nitro-carburized X10CrNiMoV1222 steel using high power diode laser (HPDL) to overcome water droplet erosion occurring in low pressure steam turbine (LPST) bypass valves and LPST moving blades used in high rating conventional, critical, and super critical thermal power plants. The materials commonly used for high rating steam turbines blading are X10CrNiMoV1222 steel and Ti6Al4V titanium alloy. The HPDL surface treatment on TWAS coated X10CrNiMoV1222 steel as well as on plasma ion nitro-carburized steel has improved water droplet resistance manifolds. This may be due to combination of increased hardness and toughness as well as the formation of fine grained structure due to rapid heating and cooling rates associated with the laser surface treatment. The water droplet erosion test results along with their damage mechanism are reported in this article.

A coupled damage model for creep

Alloy steels of type 9Cr1Mo are being developed worldwide for the boiler and turbine components of supercritical and ultra supercritical thermal power plants and for the pressure vessel of fast breeder reactors. These steels exhibit very complex high temperature creep cavitation processes with coupled influences of creep strain, material softening and ageing etc. A new viscoplastic model considering both deformation and damage evolution has been developed in this work to predict high temperature creep deformation and damage of a 9Cr1Mo steel. Smooth tensile specimens have been analysed using this new model and the evolution of creep damage has been predicted. The results have been compared with those of experiment from literature. From the initial results, it is observed that this approach is very promising to carry out design and fitness-for-purpose of service of actual plant components.

High Power Diode Laser Surface Treatment to Minimize Droplet Erosion of Low Pressure Steam Turbine Moving Blades

This article deals with the high power diode laser (HPDL) surface treatment to overcome water droplet erosion of Low Pressure Steam Turbine (LPST) moving blades used in high rating conventional, critical and super critical thermal power plants. The materials generally used in these steam turbines are titanium alloy (Ti6Al4V), precipitate hardened stainless steel (17Cr-4Ni PH), X20Cr13 and X10CrNiMoV1222 steels. During incubation period as well as under prolonged testing, the HPDL surface treatment of these materials except for 17Cr-4Ni PH steel has enhanced the droplet erosion resistance significantly. This is due to increased hardness and formation of fine-grained martensitic phase due to rapid heating and cooling rates associated with laser treatment. The droplet erosion results of HPDL laser surface treatment of all these materials and their analysis form the main part of the article.

Least cost electricity generation options based on environmental impact abatement

Abstract The power sector in Thailand is the largest contributor to CO2 emissions. There is high potential to mitigate CO2 emission via alternative power generating plants. Alternative plants considered in this study include nuclear plants, integrated gasification combined cycle plants, biomass-based plants and supercritical thermal power plants. The biomass-based plants considered here are fueled with four types of biomass; paddy husk, municipal solid waste (MSW), fuel wood and corncob. The methodology for the optimal expansion plan of the power generating system over the planning horizon is based on the least-cost approach. The results from the least-cost planning analyses show that the nuclear alternative has the highest potential to mitigate not only CO2 but also other airborne emissions. Moreover, the nuclear option is the most effective abatement strategy for CO2 reduction due to its negative incremental cost of CO2 reduction.

Optimal Control of Thermal Power Plants in Kyushu Electric Power Company

Outline of the system canfigulations and operating experiencies of the optimal regulators, which are implemented at four supercritical thermal power plants in Kyushu Electric Power Company, are described. More advanced two control systems, which are planned in the company, are also introduced. They are, (1) the control system with a feedback which is computed by Linear Programming and provides optimal pole arrangement to suppress steam temperature fluctuations due to plant load changes, and (2) an optimal regula tor wi th fee.dforward function, in which measurable disturbances to the plant are utilized for building state observers and feedback controllers. Control performances of these systems are described with some experimental results which were obtained on the system models.

Totally Computer Automated Control System in a Thermal Power Unit

One of the most advanced computer control systems for supercritical thermal power plants is discussed. The system consists of a sophisticated man-machine interface to support operators' supervisory tasks and diagnosis functions to improve plant reliability, especially during the phase of startup of the plant. Optimal control system implemented in the plant is also briefly described. By the adoption of this system high reliability of the plant was realized, and the operators' burden was considerably reduced. The units equipped with this system has been contributing to the power system operation of the Kyushu Electric Power Company.

Statistical identification for optimal control of supercritical thermal power plants

The use of a multivariate autoregressive model for the implementation of a new practical optimal control of a supercritical thermal power plant is discussed. The control is realized by identifying the system characteristics of the plant under the conventional PID control by the autoregressive model fitting and then implementing the digital control to correct the defect of the analog control. The procedure of identification and the controller implementation is described in detail by using the experimental results of a real plant. The results clearly demonstrate the advantage of the new controller over the conventional PID controller. The experience of the commercial operation of the plant confirms that the new controller is extremely robust against the gradual change of the plant characteristics, and this shows the practical utility of the identification procedure on which the design of the controller is based.

Use of Statistical Identification for Optimal Control of a Supercritical Thermal Power Plant

The use of a multivariate autoregressive model for the implementation of a new practical optimal oontrol of a supercritioal thermal power plant is discussed. The control is realized by identifying the system characteristics of the plant under the conventional PlD control by the autoregressive model fitting and then implementing the digital control to Correct the defect of the analog control. The procedure of identification and the controller implementation is described in detail by using the experimental results of a real plant. The results clearly demonstrate the advantage of the new oontroller over the conventional PID controller. The experienoe of the oOl!llleroial operation of the plant confirms that the new controller is extremely robust against the gradual change of the plant oharacteristios, which shows the practical utility of the identification procedure on which the design of the controller is based.