Operation Of Thermal Power Plants Research Articles

Using the Multi-Criteria Model for Optimization of Operational Routes of Thermal Power Plants

The constant problems evidenced in the Brazilian hydrological scenario, where the source of hydraulic potential corresponds to about 63.9% of the energy matrix, coupled with the exponential growth in the supply of renewable energy, corroborates the importance of thermal power generation as the basis of Brazilian’s energy matrix. With the operation of thermal power plants, which characteristically involve a large number of systems, subsystems, and auxiliary equipment, there is a high demand for the use of methodologies for monitoring and controlling processes, analyzing failures, and implementing improvements and actions that increase the reliability and, consequently, reduce the failure rate. In this context, decision-making about prioritizing criticality for operational monitoring of an asset’s components, from the perspective of operation and maintenance planning and based on reliability-centered maintenance (RCM) concepts, can be considered a complex task. Given this, the research seeks to demonstrate how the “Measuring Attractiveness by a Category Based Evaluation Technique (MACBETH)” method can be applied to the development of a multiple criteria model to support decision making in ordering the criticality of systems in operational inspection routes of thermal power plants, to propose new routines execution methodologies, aiming at increasing the productivity of the operation team. According to the results of the judgment matrix, the ordering proposal allowed a strategy for the execution of the current operational routes, redefining criticality, periodicity, routing, and applied resources, maintaining the reliability of the plant. It limits itself to assessing the criticality of the subsystems and monitored points belonging to the boiler system. These are typical of thermoelectric plants classified within the Rankine thermodynamic cycle and represent a significant part of the evaluation proposal.

A novel linear active disturbance rejection controller for main steam temperature control based on the simultaneous heat transfer search

The main steam temperature of boiler outlet has been deemed as a significant parameter of the safety and economic performances in the thermal power plant operation. The complex working status of the thermal generation endures highly uncertain factors and remarkable disturbance, which call for effective controlling approaches in the corresponding temperature management. The linear active disturbance rejection controller (LADRC) is a conducive and powerful controlling method, whereas strong correlation between LADRC parameters leads to difficulties in optimally determining the controller parameters. Aiming at eliminating the negative effects on main steam temperature control caused by uncertainties factors and disturbances, a high performance LADRC based on a novel parameters optimization strategy, the simultaneous heat transfer search (SHTS) algorithm, is designed to deliver a stability, rapidity, and precision of control process. In the presented SHTS algorithm, all the three phases of heat transfer are randomly and parallel operated, providing a significant improvement towards the optimization performance. The proposed algorithm is first verified on various benchmark functions contrasted to state-of-the-art counterparts in performance validating, and then adopted in the parameter selection of LADRC in the main steam temperature control system. The excellent control performance, strong robustness and disturbance rejection ability of the designed approach are illustrated through the simulation results on main steam temperature control system.

Pre-control Analysis of Dangerous Points in Centralized Control Operation of Thermal Power Plant

Pre-control Analysis of Dangerous Points in Centralized Control Operation of Thermal Power Plant

OPERATIONAL COST REDUCTION OF GAS-THERMAL POWER PLANT BASED ON BAT ALGORITHM

An optimised operation of a thermal power plant is required to optimise fuel consumption cost. It is still high and becomes a problem of economic dispatch in the operation of the plant. Load scheduling and generator capacity are needed to get optimal plant operation, especially energy usage. This paper presented a thermal power plant operation analysis to obtain optimum operational energy costs using the Bat Algorithm (BA). The actual data of 6 thermal power plants to serve the peak loads in 2018 is used for the calculation. The problem solution is simulated and calculated using maximum (95%) capacity and the BA method. The Simulation is done by using MATLAB software. The generator unit and generator load characteristics are collected to obtain objective functions and constraint functions. BA completes this function to get the lowest energy. The BA method will be compared with the calculation of real-time energy generation without BA to analyse its accuracy. The total operational cost of the actual power plant without BA is $ 1,988,410. BA simulation gave the total energy cost is $1,653,374. So, the generated energy savings is 16.85%, or 335,036 MW reduction.

Failure analysis on abnormal blockage of electro-hydraulic servo valve in digital electric hydraulic control system of 125 MW thermal power plant

Electro-hydraulic servo-valves, which are considered as the crucial core element of digital electric hydraulic control system, are widely applied in thermal power plants. In this paper, motivated by the long stable operation of thermal power plant, an abnormal blockage failure of the electro-hydraulic servo valve in digital electric hydraulic control system of 125 MW thermal power plant was investigated systematically. Three body abrasive wear was identified as the main failure mechanism. Comprehensive analysis results finally revealed that the unqualified material of the valve spool with abnormal coarse carbides caused by improper preparation process was ascribed to be the root cause of the failure. During the operation, the abnormal coarse carbides acted as stress concentration source and were peeled off from the valve spool under the effect of the friction between the feedback wire and the valve spool. After that, the exfoliated carbides served as third bodies, resulting in three body abrasive wear. In this process, some of the carbides with size exceeding 5 μm driven by fire-resistant oil entered the clearance between the valve spool and the valve sleeve, leading to the abnormal blockage failure since the maximum allowable clearance was 5 μm. Countermeasures were then proposed to address corresponding problems. Considering that practical failure of the electro-hydraulic servo-valves is seldom reported before, the finding of the paper could be helpful for better understanding the failure mechanisms of the electro-hydraulic servo-valves under actual service conditions.

The modal and harmonic response analysis of final superheater based on workbench

In order to avoid pipe failures affecting the operation of thermal power plants, the modal and harmonic response analysis method were carried out through the finite element software ANSYS Workbench to solve the long-term vibration of the final superheater at high temperature. Modal analysis can predict the natural frequencies of each stage of the structure and provide the frequency range for the harmonic response analysis. Then the response curve of stress to the frequency under the forced vibration was obtained on the base of harmonic response analysis, and observed the stress corresponding to the peak frequency. Furthermore, the fatigue life of the system was analyzed by the fatigue tool module in ANSYS Workbench. The results show that the fatigue safety factor of the final superheater pipe is greater than the allowed safety factor, and the fatigue life could meet the requirements for safe operation. The research results have certain reference value for further research on vibration fatigue of superheater pipelines.

Quantitative estimation of sea surface temperature increases resulting from the thermal discharge of coastal power plants in China

The operation of coastal nuclear power plants and thermal power plants (CNATPPs) can cause regional sea surface temperature (SST) increases. To assess their effects on coastal ecosystems, the scope and extent of their impacts must be understood. We aimed to quantitatively assess the SST increases caused by thermal discharge under climate warming by comparing SSTs between control and test groups and among different offshore buffer zones based on daily MODIS SST data from 2002 to 2017. The results showed that (1) a good correlation occurred between the CNATPP installed capacity and SST increase in the 0–2 km offshore waters; (2) the SST increase caused by thermal discharge was the largest in summer and the smallest in winter; and (3) the effect of thermal discharge occurred within 2 km offshore when the installed capacity exceeded 2000 MW and extended to 5 km when it reaches more than 4000 MW.

Synthesis of the Algorithm for Control of the Thermal Power Plant Generating Equipment Based on System Dynamics Models

The article discusses an original solution for designing an algorithm for selecting the most optimal technical and economic indicators for the operation of generating equipment of thermal power plants, taking into account the requirements of the wholesale electricity market, the day-ahead market and the balancing market. To design an algorithm for controlling generating equipment, the activity of a generating company in the wholesale electricity market was considered in terms of system dynamics. The proposed solution made it possible to select and interpret the state variables of the model, build flow diagrams describing the functioning of a technical-economic system, and visualize cause-and-effect relationships in the form of structured functional dependencies. In this work according to the norms of industry legislation and previously conducted scientific research the most important parameters were identified that form the flows of a dynamic technical and economic system, which are optimization criteria in fact. On the basis of this data, a stream stratification of the production processes of generating companies was carried out and a complex of mathematical models of system dynamics was developed to determine and plan the financial efficiency of the operation of thermal power plants and generating companies. The mathematical apparatus and the algorithm of its functioning are developed on the basis of the digraph of cause-and-effect relationships between the investigated technical and economic indicators. On the basis of the graph of interrelationships of system variables, a system of nonlinear differential equations has been built, which makes it possible to determine planned performance indicators when various technical and economic conditions change. The novelty of the proposed approach is the use of new model solutions based on the mathematical apparatus of system dynamics to represent the proposed model in simulation systems, in industry ERP and MES systems, for the development of DDS.

Determination of the Risk of Coal Supply Chain for Thermal Power Plants in Vietnam

Currently, electricity is one of the developing fields and plays an important role in the socio-economic life of Vietnam. In which, the power output provided by thermal power plants is very large. In order to ensure stable operation and high productivity of thermal power plants, the Government and people of Vietnam have been making efforts to improve the infrastructure, especially the logistics of shipping by sea to serving the operation of thermal power plants. However, shipping by sea, Vietnam still faces many challenges that need a lot of effort to solve. Currently, shipping by sea is very risky, causing negative impacts on the operation of thermal power plants. In which, the coal supply system plays an important role. Risk assessment has been recognized as a useful tool to identify hazards, analyse weaknesses and risks of shipping by sea, and select appropriate mitigation measures. A questionnaire has been compiled that includes 38 factors that create possible risk events during shipping by sea. The risk matrix is used as the basis for quantitative risk analysis to identify the most important risks that greatly affect the operation of thermal power plants and indicate solutions to control risks. Research analysis and risk assessment based on the survey questionnaire, achieved the following results: 1) Recognizing that, there are 27 major risks affecting the transport of coal by sea; 2) Scientific rating of the effect of all risks to sea transport of coal; 3) Make recommendations that can reduce or eliminate influencing factors. This study provides a valuable reference to help the investor and the contractor complete the plan, ensuring the benefits for the parties involved in the contract to perform the operation of the thermal power plant.

Оценка показателей работы теплофикационной ПТУ при изменении внутреннего относительного КПД отсеков паровой противодавленческой турбины

The authors carried out the circuit-parametric optimization studies of a promising cogeneration STU, which includes a backpressure steam turbine and a gas-fired steam boiler capable of heat recovery from flue gases. A mathematical model was employed to analyze how the internal relative efficiency of the steam turbine compartments in such an STU could affect the core operating parameters and the design characteristics of the heat exchange equipment of the unit. Mathematical modeling and circuit-parametric optimizations were run in the Machine Programming System, a software package developed by the Department of Heat and Power Systems, Melentiev Energy Systems Institute, Siberian Branch of the Russian Academy of Sciences. The optimization criterion was the price of STU-supplied electricity at the given prices of supplied heat and fuel with the adjustment for the internal rate of return on investment. Circuit-parametric optimizations show that the price of electric energy from a cogeneration STU linearly depends on the internal relative efficiency of the turbine compartments, and when it changes from 0.82 to 0.9, the price of electric energy decreases by 0.03 cents/kW. The cost effect of the increase in efficiency can be up to 98.79 thous. USD/year given the quantitative supply of electricity from the STU. The methodological approach used in this work enables feasibility testing of the attempts to improve the internal relative efficiency of the steam turbine compartments and can be useful both in the design and operation of thermal power plants. The estimated effects of internal relative efficiency of the turbine compartments on the core operating parameters and the characteristics of the unit will help determine the reliability and efficiency of its operation.

ПРОБЛЕМЫ И ПЕРСПЕКТИВЫ СОЗДАНИЯ ЭКОЛОГИЧЕСКИ БЕЗОПАСНОЙ ТЭС НА ТВЕРДЫХ КОММУНАЛЬНЫХ ОТХОДАХ

The article consider the main stages in the selection of an environmentally safe structure of thermal and energy solid municipal waste utilization as part of the feasibility study. The article analyses the assessed in-fluence of the fuel component on the structure of a waste-to-energy plant (WTE plant). Recommendations on how to select the optimal energy structure of WTE plant have been developed, an approach to the analy-sis of the ash and slag management scheme has been investigated. The approach to the choice of the struc-ture of the WTE plant gas purification system is selected. The article reveals significant differences in the approach to determining the structure of the energy TPP and WTE plant and provides recommendations on the ways to reduce capi-tal costs while maximizing the extraction of secondary resources. The methodology of the study consists in the analysis of foreign experience in the operation of thermal power plants on MSW with various structural schemes, presented in the literature, reports on the operation of energy complexes, passports for installa-tions. The purpose of creating the methodology is to determine the projected environmental and energy in-dicators of the projected WTE plant and, taking into account external and internal factors of the project, identify possible risks of the project at the stage of feasibility study.

The effect of mixtures of neutralizing amines on the dynamic exchange capacity of strong acid cationite KU-2-8

The dependence of the ion exchange capacity of strong acid cationite KU-2-8 on the concentration and structure of low-molecular organic compounds containing an amino group has been experimentally established. The mutual influence of neutralizing amines that are part of complex reagents that reduce the value of the exchange capacity of cations during operation of thermal power plant was revealed.

Conceptual Design of a Hybrid Fusion–Fission Power Reactor with a Tokamak and a Depleted Uranium Blanket

We assess the viability of energy generation with depleted uranium irradiated with fast neutrons from the reaction of DT fusion driven by a tokamak reactor. Since existing nuclear power plants employ uranium fuel enriched to 4.5% 235U, over 90% of natural uranium currently goes to nuclear waste and is no longer used for power generation. The amount of depleted uranium with the 235U content of 0.2–0.3% accumulated in the world exceeds 1 500 000 t and is continually increasing owing to the operation of thermal neutron power plants. Industrial fast neutron power plants using depleted uranium as nuclear fuel are still at the development stage. Therefore, alternative approaches to utilizing depleted uranium for power generation should be considered. Compared to fast reactors with a closed cycle utilizing plutonium, the proposed facility involves less radiation hazard since the irradiated fuel has to be reprocessed and reloaded less frequently. Apart from that, the proposed hybrid power reactor operates in the deeply subcritical regime, which provides a high level of nuclear safety. A tokamak reactor similar to that of the ITER project is selected as a source of a high-power flux of fusion neutrons whereby a reactor blanket of depleted uranium is irradiated. The heat will be removed with a liquid metal coolant rather than with water as in the ITER reactor. This will help maintain the hardness of the neutron spectrum, thereby maximizing the rate of 238U fission. With such a neutron source and a blanket of natural uranium with an optimized thickness of ~20 cm, each fission of uranium (with an energy release of 200 MeV) is estimated to finally produce four 239Pu atoms in the blanket (see the 2009 proceedings of the ROSATOM commission on optimizing the development of power generation with tokamaks). This estimate equally applies to a reactor blanket of depleted uranium. According to estimates, an “ideal” reactor with a blanket of depleted uranium operating in a stationary mode with a capacity factor of 70% would generate nearly 1.5 GW of electric power. However, only an estimated one-third of the total power can actually be delivered to the electrical network since the rest is required for breeding tritium and powering the facility itself. Toward maximizing the capacity factor, the first wall of the fusion reactor will be coated with lithium for protection against plasma-induced erosion.

Modeling of the Optimization Procedure for Selecting the Location of New Thermal Power Plants (TPP)

At the level of design of thermal power plants (TPP), when making decisions related to the choice of its macro location and micro location, disposition solution and equipment structure, the choice of the right decision method is of particular importance. Multi criteria analysis involves solving inadequately structured problems, while in practical terms it is a necessary tool in solving the day-to-day tasks of decision-making, management actions, both at the design level and the exploitation of complex energy and process systems. The development of new methods and the improvement of existing multi criteria analysis methods have influenced their increasing application in the field of energy, from both theoretical and practical aspects. A particular segment of the application of multi criteria analysis methods is to make strategic or operational decisions when solving multidisciplinary problems with predominantly technical or predominantly economic content, whether looking at a part or the energy system as a whole. The application of these methods in choosing the right solutions in the decision-making tasks of management in the design, maintenance and operation of thermal power plants is based on the development of information technology and computer technology. There are several methods in use today, of which the following should be emphasized: PROMETHEE (Preference Ranking Organization METHod of Enrichment Evaluation), AHP (Analytic Hierarchy Process), IKOR, ELECTRE (ELimination Et Choice Translating REality), MAX-MIN, MAX-MAX, Hurwicz (combination of max-max and max-min methods), SAW (Simple Additive Weighting Method), TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), conjunctive method, disjunctive method, etc. Depending on the method used, the ranking of alternatives or criteria, the best alternative or criterion or set of alternatives or criteria that meet certain conditions is obtained as a solution. Problems that can be considered using multi-criteria decision-making have certain common characteristics: a large number of criteria that must be created by the decision maker, a high likelihood of conflict between the criteria, inseparable (different) units of measure (as a rule, each criterion has different units of measure), as well as design or the choice of optimal concepts in a predetermined space. Solutions are either designing the best alternative or choosing the best action from a set of predefined final actions. This paper provides a brief description of the more important methods, along with an analysis of their advantages and disadvantages, as well as the possibility of applying them to solve the specific problem of choosing a micro location for TPP. Starting from the application of the modified multi criteria method for determining the priorities between individual alternatives for ranking and selecting the optimal micro location within a certain macro location within a predetermined framework, in a decision situation involving a number of decision makers of different specialty, examples of micro location selection for new thermal power facilities of TPP Stanari are given, TPP Gacko 2 and TPP Ugljevik 3, with preliminary definition of elimination criteria and criteria for comparison of locations of given TPPs.

Creep lifetime prediction of 9Cr-1Mo (grade T91) steel via small punch creep tests and hierarchical multiscale analysis

ABSTRACT In this study, the creep deformation of ferritic/martensitic 9Cr-1Mo (Grade T91) steel boiler tubes that occurs during the operation of thermal power plants is studied using crystal elasto-viscoplasticity finite element analysis (CEV-FEA). The material properties and creep behaviour of Grade T91 were obtained through experimentation and computational analysis at different scales, e.g., molecular dynamics simulation, scanning electron microscopy, small punch (SP) tests. A triple junction of grains with various combinations of crystallographic orientations of polycrystalline Grade T91 was also simulated by CEV-FEA to investigate the stress concentration evolution during creep deformation. The stress concentration at the triple junction was then used as an input for the creep cavitation model, i.e., as the representative stress driving creep cavitation. The combination of CEV-FEA and SP test experiments can improve the evaluation of creep lifetime for as-received boiler tubes with minimum requirements for the amount of material and testing time.

Development of magnetic separation system for thermal power plants

Assuming that the high‐gradient magnetic separation (HGMS) system based on a superconducting magnet can reduce iron oxide scale in boiler feedwater and contribute to the efficient operation of thermal power plants, we design a new matrix structure, which should efficiently capture iron oxide particles in boiler feedwater. We then evaluate their practicability experimentally and confirm that this HGMS system with the newly developed matrix is applicable to thermal power plants with the desired efficiency. On the bases of the results, we designed practical large‐scale HGMS systems for boiler feedwater with a superconducting magnet and new matrices, which has long cleaning cycles and low‐pressure loss. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Hybrid modelling and digital twin development of a steam turbine control stage for online performance monitoring

Increasingly tight integration of renewable power sources with thermal power sources leads to frequent operation at off-design modes of thermal power plants. It brings challenges including reduced efficiency, increased costs and safety issues in power plants. At a component level, load changes of thermal power plants are mainly carried out through actions of control stage systems of steam turbines. Accurate performance monitoring of control stage systems is key to enable faster and more flexible operation of thermal power plants thus provides opportunities to accommodate more renewable power with limited penalty to efficiency and safety. In this paper, a hybrid modelling method based on operation data and first-principle mechanism is proposed for performance monitoring of control stage systems. The hybrid modelling method features a) flow rate calculation of high-pressure control valves with limited measurement data, and b) flow and efficiency characteristics calculation over full working ranges of control stages. The proposed hybrid modelling method is validated via two case studies of a 330 MW subcritical steam turbine and a 1000 MW ultra-supercritical steam turbine, where digital twins of control stages are developed. Results show that average relative errors between simulated and measured values of exit pressure and exit temperature of control stages are within a range of one percent, providing great potential for plant-wide digital twin development and online performance monitoring.

Increasing the integration of variable renewable energy in coal-based energy system using power to heat technologies: The case of Kosovo

The goal of this work is to identify the influence which utilization of district heating systems coupled with the power-to-heat technologies based on the flexible operation of coal-based thermal power plants and limited electricity system interconnections can have on the maximum integration of variable renewables. An hourly deterministic tool EnergyPLAN was used for modelling and simulation of Kosovo energy system. Results revealed that Wind and PV power plant capacities of 450 MW and 300 MW respectively can be installed in the actual Kosovo energy system, when operating in an isolated mode. Additional capacities around 800 MW for wind and 385 MW for PV can be integrated into this isolated energy system with the contribution of power-to-heat technologies coupled with thermal energy storage in district heating with a fixed capacity. Furthermore, it was found that separate integration of wind can contribute to decease total primary energy supply and CO2 emissions for 3.34 TWh/year and 1.08 Mt compared to the referent scenario. Total primary energy supply and CO2 emission savings for separate integration of PV power plant compared with the referent scenario were estimated 2.74 TWh/year and 0.5 Mt respectively. Finally, the combined integration of variable renewable energy sources (1MWW+1MWPV) contributed to 3.29 TWh/year total primary energy supply and 1.02 Mt CO2 emissions savings.

Experimental Modeling of the Optimized Motion Control of Electromechanical Actuators Used in Thermal Power Plants

Abstract The purpose of scientific research in this paper is to improve the operation of thermal power plants. The experimental stand for the study was made for testing, verifying and adjusting the dynamic parameters of the electromechanical actuators that are integrated in the gas valve component. In order to improve the performance of the thermal power plants by increasing the energetic, mechanical, electrical efficiency, this will be achieved through an alternating-alternative static converter, experimentally realizing the single-phase alternating voltage variable module. System optimization is to find new solutions for controlling the linear motion of electromechanical actuators, including the choice of working principles that would become patent proposals, or new research stands.

Theoretical and Experimental Aspects of Signal Analysis Applied to Solenoid-Type Actuators Used in Gas Valves

Abstract The purpose of scientific research in this paper is to control the movement of solenoid actuators, by analyzing the applied signal. The actuator in a system is the execution element. The optimization of the system consists in finding new solutions for motion control for solenoid actuators, by designing and experimental realization of a static converter, also called alternating voltage inverter (VTA), which would become proposals for patents, or the realization of new experimental research stands. By analyzing the signal in this paper, it will be possible to design, experiment and test different types of VTA (with Arduino development boards, Raspberry Pi single board computers, logic gates) that will improve the reliability, future operation of thermal power plants.