scholarly journals Modelling and combustion optimization of coal-fired heating boiler based on thermal network

2021 ◽  
Vol 25 (4 Part B) ◽  
pp. 3133-3140
Author(s):  
Chao Chen ◽  
Jinhong Mao ◽  
Xinzhi Liu ◽  
Shan Tian ◽  
Lijun Song
Keyword(s):  
Thermal Efficiency ◽  
Mass Concentration ◽  
Optimization Problem ◽  
Weight Coefficient ◽  
Nox Emission ◽  
Hybrid Modelling ◽  
Thermal Network ◽  
Calibration Samples ◽  
Combustion Optimization ◽  
Power Station Boiler

Based on the thermal network and the MATLartificial intelligence toolkit, a combustion optimization hybrid modelling of a 300 MW coal-fired power station boiler is carried out. The boiler is optimized for combustion, and the weight co?efficient method is used to convert the multi-objective optimization problem into a single-objective optimization problem. The results show that the relative error average absolute value of the boiler thermal efficiency and NOx emission mass concentration calibration samples are 0.142% and 1.790%, the model has good accuracy and generalization ability. The weight coefficient method can select the corresponding weight coefficient according to the actual situation, with the boiler thermal efficiency or NOx emission mass concentration as the optimization focus, which has certain guiding significance for combustion optimization.

Development of a Methodology for Determining the Best Option for the Route of the Heat Network at the Initial Design Stage

2021 ◽  
pp. 57-64
Author(s):  
А. А. Чуйкина
Keyword(s):  
Mathematical Model ◽  
Vector Optimization ◽  
Optimization Problem ◽  
Pairwise Comparison ◽  
Design Stage ◽  
Heat Network ◽  
Thermal Network ◽  
Initial Design ◽  
Matrix Generalization ◽  
Joint Application

Постановка задачи. Выбор наилучшего варианта трассы тепловой сети на начальном этапе проектирования является сложной многофакторной задачей, кроме того, ввиду отсутствия ряда необходимых конструктивных расчетов ее решение сопровождается ограниченностью набора исходных данных. Таким образом, становится актуальной разработка новой методики проектирования оптимальной трассы системы теплоснабжения, учитывающей качественные и количественные характеристики рассматриваемого объекта. Результаты. Разработана математическая модель обобщенного аддитивного векторного критерия оптимальности, учитывающая материалоемкость тепловой сети, ее надежность, время строительства, годовые тепловые потери, оборот теплоты и дисперсию температуры у потребителя. Предложен способ определения наилучшего варианта трассы тепловой сети на начальном этапе проектирования путем совместного решения задачи оптимизации методами векторной оптимизации и матричного обобщения. Отмечена целесообразность совместного применения методов попарного сравнения и векторной оптимизации при решении рассматриваемой задачи. Выводы. Важной характеристикой разработанной математической модели обобщенного критерия является возможность получения более точного решения рассматриваемой оптимизационной задачи при неравномерным распределении тепловой нагрузки посредством смещенной оценки дисперсии температуры у потребителей. Совместное применение методов матричного обобщения, попарного сравнения и векторной оптимизации позволяет повысить точность расчета при решении оптимизационной задачи выбора наилучшей трассы тепловой сети. Statement of the problem. Choosing the best option for the route of the thermal network at the initial stage of design is a complex multifactorial task, in addition, due to the lack of a number of necessary design calculations, its solution is accompanied by a limited set of initial data. Thus, it becomes relevant to develop a new methodology for designing the optimal route of the heat supply system, taking into account the qualitative and quantitative characteristics of the object under consideration. Results. A mathematical model of a generalized additive vector optimality criterion has been developed, taking into account the material consumption of the heat network, its reliability, construction time, annual thermal losses, heat turnover and temperature dispersion at the consumer. A method is proposed for determining the best option for the route of a thermal network at the initial design stage by jointly solving the optimization problem using vector optimization and matrix generalization methods. The expediency of the joint application of the methods of pairwise comparison and vector optimization in solving the problem under consideration is noted. Conclusions. An important characteristic of the developed mathematical model of the generalized criterion is the possibility of obtaining a more accurate solution to the optimization problem under consideration with an uneven distribution of the heat load by means of a biased estimate of the temperature variance among consumers. The combined application of the methods of matrix generalization, pairwise comparison and vector optimization can improve the accuracy of the calculation when solving the optimization problem of choosing the best route of the thermal network.

Impact of Oxidation Inhibitors on Performance and Emission Characteristics of a Low Heat Rejection Engine

2017 ◽  
Vol 8 (4) ◽  
Author(s):  
P.S. Kumar ◽  
S.A. Kannan ◽  
A. Kumar ◽  
K.A.V. Geethan
Keyword(s):  
Combustion Chamber ◽  
Fuel Consumption ◽  
Thermal Efficiency ◽  
Specific Fuel Consumption ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Brake Thermal Efficiency ◽  
Heat Rejection ◽  
Oxidation Inhibitors ◽  
Low Heat Rejection Engine

In this study, for the first time analysis of a low heat rejection engine was carried out along with the addition of oxidation inhibitors. If the combustion chamber components of the engine such as piston, cylinder head, and inlet and outlet valves are insulated with a thermal barrier material, then the engine will be referred as low heat rejection engine. In this study yttria stabilized zirconia was coated on the combustion chamber components for a thickness of about 150 microns. Then the analysis of performance parameters such as brake thermal efficiency and specific fuel consumption and emission characteristics such as emission of carbon monoxide, hydrocarbon and nitrogen oxide was carried out in single cylinder four stroke diesel engine with electrical loading using diesel and pongamia methyl ester as the fuels. The major problem associated with the usage of biodiesels and low heat rejection engine is the increased NOX emission than the normal engine operated with the diesel. This problem has been overcome by the usage of oxidation inhibitors such as ethyl hexyl nitrate (EHN), tert-butyl hydroquinone (TBHQ). The results showed that addition of oxidation inhibitors leads to increase in brake thermal efficiency, reduced specific fuel consumption and reduced NOX emission.

Use of CFD Modeling for Design of NOx Reduction Systems in Utility Boilers

2002 ◽  
Author(s):  
Bradley Adams ◽  
Marc Cremer ◽  
James Valentine ◽  
Venkata Bhamidipati ◽  
David O’Connor ◽  
...  
Keyword(s):  
Nox Reduction ◽  
Field Testing ◽  
Nox Emission ◽  
Injection System ◽  
Cfd Modeling ◽  
Unburned Carbon ◽  
Port Placement ◽  
Utility Boilers ◽  
Ammonia Slip ◽  
Combustion Optimization

CFD modeling has found increasing use in the design and evaluation of utility boiler retrofits, combustion optimization and NOx reduction technologies. This paper reviews two recent examples of CFD modeling used in the design and evaluation of NOx reduction technologies. The first example involves the staging of furnace combustion through use of overfire air (OFA) to reduce NOx emission in a B&W opposed-wall fired pc furnace. Furnace simulations identified locations of highest flue gas mass flows and highest CO concentrations and were used to identify OFA port placement for maximum NOx reduction with lowest increases in unburned carbon in fly ash and CO emission. Simulations predicted a 34% reduction in NOx emission with OFA. The second example summarizes the design and application of RRI with OFA and SNCR in a 138 MW cyclone-fired boiler. Simulations were used to design an aminebased injection system for the staged lower furnace and to evaluate NOx reduction and ammonia slip of the RRI system. Field-testing confirmed modeling predictions and demonstrated that the RRI system alone could achieve 25–30% NOx reduction beyond OFA levels with less than 1 ppm ammonia slip and that RRI in combination with SNCR could achieve 50–55% NOx reduction with less than 5 ppm slip.

High Efficiency and Low NOx Gas Engines for Co-Generation Markets

2001 ◽  
Author(s):  
Satoru Goto ◽  
Sadao Nakayama ◽  
Yoshiharu Ono ◽  
Yoshifumi Nishi
Keyword(s):  
Combustion Chamber ◽  
Thermal Efficiency ◽  
Nox Emission ◽  
Fuel Oil ◽  
Lean Burn ◽  
Fuel Gas ◽  
Gas Density ◽  
Emission Level ◽  
Spark Plug ◽  
Pilot Fuel

Abstract Lean-burn gas engines are operating worldwide because of having an advantage of lower NOx emission and higher thermal efficiency than those of stoichiometric gas engines. The modern lean-burn gas engines, especially medium and large size, have the pre-combustion chamber technology. On the contrary, there are some problems that originate in the spark plug. Particularly near the ignition plug located in the center, the fuel gas density is lean, affected by the lean-gas mixture coming from the main combustion chamber during the compression stroke and the fuel gas density near the wall is rich. The lifetime of ignition plug is likely to be shorter than those used in the conventional theoretical mixture gas combustion engine, because the required voltage for the plug is high, which reaches 20–25 kV or more. The authors and their colleagues have studied a combustion method of using micro-pilot fuel oil instead of spark plug as an ignition source in recent four years to provide a solution for the above mentioned technical problems. The energy of micro-pilot fuel oil is equivalent to 1% of the total thermal input, but the energy of the pilot fuel oil is several thousands times of the spark ignition. According to the author’s study, NOx emission level is defined by the amount of pilot fuel oil. But only about 1% fuel can meet the NOx target. NOx emission level meets TA-Luft of 500 mg/m3N @ 5% O2. Even the regulation of 200 ppm @ 0% O2 in the Japanese large cities can be achieved, this level is almost corresponding to the half TA-Luft. This paper describes the performance being desired for gas engines through the service-experience in co-generation fields and also describes the newly developed gas engine corresponding to a 1000 kW class, which has micro-pilot fuel oil ignition method. This engine has the same performance of a diesel engine, BMEP of 2.3 MPa and brake thermal efficiency of 43%.

NOx emission and thermal efficiency of a 300MWe utility boiler retrofitted by air staging

2009 ◽  
Vol 86 (9) ◽  
pp. 1797-1803 ◽  
Author(s):  
Sen Li ◽  
Tongmo Xu ◽  
Shien Hui ◽  
Xiaolin Wei
Keyword(s):  
Thermal Efficiency ◽  
Nox Emission ◽  
Utility Boiler ◽  
Air Staging

scholarly journals Pengaruh Dimensi Kompor Biomasa Terhadap Performansinya

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Ahsonul Anam
Keyword(s):  
Thermal Efficiency ◽  
Consumption Rate ◽  
Nox Emission ◽  
Biomass Fuel ◽  
Burning Time ◽  
Gas Analyzer ◽  
Gas Emission ◽  
Biomass Stove ◽  
D 20 ◽  
Co Emission

Abstrak: Desain kompor berbahan bakar biomasa untuk keperluan memasak, dimaksudkan untuk mendapatkan performayang optimal. Performa dilihat dari efisiensi pembakaran, efisiensi termal, dan emisi gas buang. Ketinggian ruang bakarkompor biomasa didesain sama dengan diameternya (H = D) atau 1-2 kali diameter (H = 1-2 D). Pada penelitian ini digunakandua buah kompor dengan perbedaan ketinggian ruang bakar (H1 = 20 cm dan H2 = 27 cm), dan diameter (D = 20 cm) danmenggunakan bahan bakar biomas yang sama. Performa dari kedua kompor diukur dari efisiensi termal, laju konsumsi bahanbakar, efisiensi pembakaran dan emisi gas buang. Pemantauan emisi gas buang dianalisa dengan menggunakan gas analyzerportabel. Hasil efisiensi pembakaran kedua kompor berbeda yaitu 99,5% (kompor 1) dan 98,2% (kompor 2). Efisiensi termaldari kompor 1 dan 2 adalah 25,4 dan 11,1%. Laju konsumsi kompor 1 relatif stabil dibandingkan dengan kompor 2 selamapembakaran. Emisi CO yang dihasilkan dari kompor 1 dan 2 adalah 328 dan 555 ppm. Hasil gas buang SOx dari kompor 1 dan2 adalah 31 dan 38 ppm. Sedangkan emisi gas buang NOx dari tungku 1 dan 2 relatif berbeda dengan nilai 19 dan 13 ppm.Kata kunci: kompor biomasa, efisiensi pembakaran, efisiensi termal, emisi gas buangAbstract: Design of the stove based on biomass fuel for cooking system have been performed. The performances are evaluatedby burning efficiency, thermal efficiency, and flow gas emission. Design of high (H) and diameter (D) of biomass furnace is 1until 2 times of the diameter. In this research, the 2 stoves with difference of high of furnace (H1 = 20 cm and H2 = 27 cm) andsame of diameter (D = 20 cm) and biomass fuel was used.  The performance of stoves are measured from thermal, fuelconsumption rate, burning efficiency and flow gas emission. Portable gas analyzer is used to monitor of emission gas (CO,SOx, NOx). The results of burning efficiency of both stoves are different, that is 99.5% (stove 1) and 98.2% (stove 2). Thermalefficiency of stove 1 and 2 are 25.4 and 11.1%, respectively. The consumption rate of stove 1 is relatively stable depend onstove 2 as long as burning time. The CO emission of stove 1 and 2 are 328 and 555 ppm. The results of stove 1 and 2 for SOxemission are 31 and 38 ppm.  The NOx emission of stove 1 and 2 are different with value of 19 and 13 ppm.Keyword: biomass stove, burning efficiency, thermal efficiency, flow gas emission

scholarly journals Optimization of Marine Medium Speed Diesel Engine Performance based on Multi-Injector System

2021 ◽  
Vol 236 ◽  
pp. 01026
Author(s):  
Dai Liu ◽  
Yingzhu Guo ◽  
Long Liu ◽  
Qian Xia ◽  
Yong Gui
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Engine Performance ◽  
Injection Rate ◽  
Nox Emission ◽  
Spray Angle ◽  
Medium Speed ◽  
Injector System ◽  
Marine Medium

Multi-injector system is potential to improve thermal efficiency and NOx emission of diesel engine at the same time. In order to optimize the combustion and emission of Marine medium speed diesel engine, the engine combustion with a multi-injector system is simulated and analyzed by CFD software Converge. In this research, two injectors are installed at the side of the cylinder head while the central injector is maintained. Various injection directions of side injectors and injection strategies of multi-injector system are simulated to optimize the fuel spray and combustion. The analysis results show that the spray angle of the side injector plays a key role for effective thermal efficiency improvement, since complex spray jet-jet interaction and spray impingement may deteriorate the combustion if the arrangement of spray angle was not set properly. Once the fuel injection direction has been optimized, the fuel ratio of the three injectors is optimized and improved the effective thermal efficiency with lower NOx emission. The results show that the two side injectors could increase the fuel injection rate into the cylinder, leading to high brake power and consequently increased the thermal efficiency by 1.26% and decreased the NOx emission by 16% for the best optimization.

Iterative learning control for consensus of second-order multi-agent systems with interval uncertain topologies

2021 ◽  
Author(s):  
Liming Wang ◽  
Guoshan Zhang
Keyword(s):  
Iterative Learning Control ◽  
Optimization Problem ◽  
Sliding Mode ◽  
Weight Coefficient ◽  
Second Order ◽  
Iterative Learning ◽  
Multi Agent Systems ◽  
Optimal Weight ◽  
Agent Systems ◽  
Multi Agent

Abstract This paper is devoted to the robust consensus tracking problem of second-order nonlinear multi-agent systems (MASs) with the interval uncertain topologies. For the second-order MASs including one leader agent and multiple follower agents, a control protocol is proposed by combining the iterative learning control scheme with the sliding mode control method. By analyzing the convergence of sliding mode variables, the consensus conditions including the unknown eigenvalues and the undetermined weight coefficient are obtained. In order to deal with the difficulties of weight coefficient design caused by the unknown eigenvalues of graphs, a min-max optimization problem is formulated based on the fastest convergence of the λ-norm of sliding mode variables, then the optimal weight coefficient is obtained by solving the min-max optimization problem. Moreover, for the undirected and directed interval uncertain graphs, two algorithms about the optimal weight coefficients are proposed, respectively. Finally, three numerical simulation examples are presented to demonstrate the effectiveness of the proposed methods.

Optimization of a Marine Medium-Speed Engine With Multi-Injector System by 1D Predictive Simulation

2021 ◽  
Author(s):  
Dai Liu ◽  
Peng Zhang ◽  
Long Liu ◽  
Qian Xia ◽  
Xiuzhen Ma
Keyword(s):  
Diesel Engine ◽  
Thermal Efficiency ◽  
Engine Performance ◽  
Nox Emission ◽  
Combustion Model ◽  
Injection Timing ◽  
Engine Model ◽  
Medium Speed ◽  
Injector System ◽  
Marine Medium

Abstract The thermal efficiency and emission of large bore marine medium-speed diesel engine are required to be improved under the stringent legislations. A multi-injector system has been proposed in order to improve the thermal efficiency and NOx emission instantaneously. However, application of the multi-injector system increased the complexity of parameter optimization and control. To develop proper control strategy of the novel multi-injector system, a 1D engine model of the original engine configurations was developed initially, including a predictive combustion model in commercial 1D simulation program (GT-Power). After calibrated by test results and literature data under various engine loads, the engine model was modified from a central single injector engine to a multi-injector engine. On the basis of a conventional direct-injection diesel engine, another two injectors were added to the cylinder as side injectors in the model. And the fundamental combustion characteristics and engine performance of the marine medium-speed diesel engine with multi-injector are investigated under various injection quantity ratio between the central injector and side injectors. The effects of injection timing and split injection are also studied by simulation. The result indicated that the effective thermal efficiency and NOx emission of the medium speed marine diesel engine are optimized instantaneously by changing the injection strategies of the central and side injectors. Finally, the preferred injection strategy is proposed by the 1D model.

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