Search

[Introduction] The realization of "dual carbon" goals in the construction of a new power system necessitates the transformation of existing thermal power plants to accommodate peak load operations. The safety of thermal power units during flexible operation is a critical element for enhancing the overall stability of the power system. Air preheater is the key auxiliary equipment that affects the wide-load operation capacity of thermal power units. This paper addresses the challenges associated with flue gas temperature fluctuations and blockage and corrosion induced by excessive ammonia injection. It is very important to develop a real-time assessment and safety status monitoring model for dust and blockage of rotary air preheaters. [Method] Based on the big data of wide-load operation monitoring of 600 MW and 350 MW units in central China, the paper developed a model for air preheater blockage assessment based on approximation of the resistance coefficients in the case of various time scales. Furthermore, the flue gas temperature at the outlet of the air preheater and the cold end working temperature were used as monitoring indicators to count the proportion of parameters exceeding the limit in multiple load sections of the unit. [Result] The results show that, at a peak regulation load of 39%, there is approximately a 20% probability of temperature exceedance. In addition, the independent calculation of the blockage risk based on the two indicators may result in a certain degree of underestimation of its degradation rate compared to the calculation based on a joint distribution. Besides, with the verification of data from the two units, the method can quantify the short-term (within the soot-blowing cycle) and mid-and-long term evolution of the air preheater blockage. [Conclusion] This assessment strategy applies to other equipment and systems in thermal power plants, such as SCR denitrification systems and coal mills, providing a quantitative assessment of safety risks during peak load operation. It guides thermal power units to efficiently and stably cooperate with the new power system in dispatching.

ObjectivesIn order to solve the shortcomings of the traditional preventive maintenance method of air preheater in large thermal power unit, a general mode of predictive maintenance based on digital twin was proposed, and the digital twin system of air preheater was constructed based on digital twin technology.MethodsThe proposed system included physical entity of rotary air preheater, real-time data acquisition and analysis module, digital twin model construction module, thermal parameter state monitoring, rotor thermal field video and thermal deformation visualization and ash accumulation prediction module. By the real-time acquisition of temperature parameter state and video data, and through the temperature field, video image, air leakage calculation and other modules, the calculation of thermal parameters and the prediction of ash accumulation were realized. At the same time, the 3D configuration screen was used to display data in real time, continuously optimize the accuracy of thermal parameter calculation and ash accumulation prediction, and realize the automatic optimization of soot-blowing strategy.ResultsThe proposed scheme realizes the state monitoring and dynamic control of the thermal calculation process of the air preheater, and solves the problem that the ash accumulation factor of the rotary air preheater in the existing power station affects the safe and reliable operation of the thermal power unit.ConclusionsThrough engineering testing of actual units, the proposed scheme effectively improves the operation and maintenance efficiency of the air preheater of thermal power units, verifies the feasibility of the proposed method, and provides technical support for the development of smart power plant systems in future.

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article introduces the upgrading and renovation of the waste heat recovery system of the No. 1 jet fuel hydrogenation unit of SINOPEC Hainan Refining & Chemical Co., Ltd. The renovation plan is as follows: By recalculating the thermal efficiency and load of the heating furnace, the original heat pipe preheater is planned to be optimized into a new ceramic regenerative air preheater. The specific renovation content is as follows: Remove the heat pipe preheater originally installed on the top of the heating furnace, and add four sets of ceramic regenerative air preheater modules on the side ground of the reaction feed heating furnace ; Reuse the original induced draft fan as a cold flue gas induced draft fan; Add a blower and smoke and air duct. The results show that after the implementation of the modification, the exhaust gas temperature of the heating furnace can be reduced to below 70 °C, the thermal efficiency of the heating furnace can be increased to over 95%, the exhaust gas temperature can be flexibly adjusted, and the fuel gas consumption of the heating furnace can be reduced by about 10%. The system has good anti-corrosion performance and is stable and reliable during long-term operation of the unit. [ABSTRACT FROM AUTHOR]

The high pressure difference between the inlet and outlet of the air preheater in coal-fired power plants has always been a problem that plagues the operation of the power plant. If the pressure difference of the air preheater can be predicted in advance and adjusted in time, it will be beneficial to the safe operation of the power plant. Based on the distributed control system (DCS) big data of a 660 MW coal-fired boiler, the BP neural network and support vector regression (SVR) methods were used to model the pressure difference between the inlet and outlet of air preheater in the power plant.Comparing the prediction results of the two models, it is found that the BP neural network model is more suitable for the prediction of the pressure difference between the inlet and outlet of the air preheater under the background of big data. Aiming at the inherent shortcomings of BP neural network model such as local optimization and slow convergence speed, the particle swarm optimization (PSO) was used to improve it, and a PSO-BP neural network model was proposed. The results show that the PSO-BP neural network model has the best comprehensive performance, the highest accuracy in predicting the change in the pressure difference between the inlet and outlet of the air preheater, and the strongest generalization ability.

In this study, the waste heat loss of flue gases from the boilers of Kafkas University district heating system has been calculated between 6-8% according to the combustion analysis and the annual cost of this heat loss has been found as $58,658.79. In terms of energy efficiency and the national economy, we think that this lost energy should be recovered as much as possible and fuel and energy savings should be achieved. In the paper, the effects of variants such as air excess coefficient, flue gas temperature, boiler capacity and fuel consumption on the heat recovery from flue gas have been presented in detail. The heat recovery scenarios have been presented for reusing this waste energy for space heating, domestic hot water, and preheating combustion air and the applicability of these scenarios has been investigated in terms of thermodynamics and economics. According to the results of the study, in the second scenario examined to cover the domestic hot water need of the guest house building, the energy savings of the scenario can be provided during 20 years of economic life is $122,820.83, and it has the highest savings income among the scenarios. In addition, it is possible to recover approximately 50% of the flue gas loss with thanks to the scenario. On the other hand, the third scenario of heating the boiler combustion air with waste heat is the easiest and most economical scenario because its payback period is only one year, and there are no extra excavation and pipe costs. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present work, a numerical study has been done for the air preheater equipped with different types of helical inserts inside the tubes with segmental baffles in shell. The simulations have been carried out to analyse the heat transfer rate in terms of heat transfer coefficient and friction factor with ANSYS 18.0. The air preheater is divided into two sections shell side and tube side, which contains ambient air and flue gases respectively. The air preheater consists of 34 tubes with a length of 3 m. In the present study, three different types of inserts are investigated with a pitch to diameter ratio (p/d) of 2, 1.7 and 1.4, and the number of turns of 100, 87 and 73, respectively. The insert under study is helical shaped with circular cross-section of diameter 20 mm. Four different values of Reynolds number are used in the range of 4000–24,000. The effects of pressure drop, heat transfer coefficient on different pitch to diameter ratio (p/d) 2, 1.7 and 1.4 of inserts and on the plain tube are discussed in this present work. The results of an air preheater with inserts in tubes get higher value of heat transfer coefficient as compared to the plain tubes. The thermal performance factor of air preheater with inserts of (p/d = 1.4) shows higher factor of 2.31 as compared to the plain tubes at low Reynolds number. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel regenerative heat exchanger was designed and fabricated for heat recovery of dryer flue gases with a high porosity matrix core that was made of alumina foams. The effects of matrix height, matrix linear speed, and flow rate on thermal effectiveness were investigated based on an L25 Taguchi model. Results show that the matrix height and flow rate are inversely related and the matrix speed is directly related to the thermal effectiveness. Finally, the highest thermal effectiveness, thermal improvement of the dryer, air preheating rate, and the number of transfer units were 31.75%, 27.13%, 186.42%, and 0.4652, respectively. [ABSTRACT FROM AUTHOR]

In this work, a micro-combustor (MC) air preheater as the heat source is developed. This novel air preheater has a compact size and outputs hot air with a wide range of temperatures with high temperature uniformity, which can well meet the preheating needs of Li-ion batteries in cold environments. Numerical studies are carried out to investigate the effects of baffle height, number of fins N fin , hot air inlet velocity, cold air inlet velocity and combustor inlet velocity on the performance of the air preheater. The heating power of the air preheater can be adjusted by changing combustor inlet velocity V combustor , the outlet temperature can be easily adjusted by changing cold air inlet velocity V cold and hot air inlet velocity V hot , and the addition of baffles makes the outlet temperature very uniform. The results show that the height of the baffle of 20 mm and 30 mm makes Δ T air not exceed 1.5 K. The air preheater performance is better with fin number 6, and the maximum air temperature of 309.8 K is obtained with fin number and V hot of 6 and 0.3 m/s respectively. T air can vary between 287.8 K and 309.8 K when V combustor = 12 m/s. • A micro-combustor air preheater for the cold start of Li-ion battery packs is developed. • Effects of different factors on the low-temperature preheating performance is investigated. • Optimized parameters of the micro-combustor air preheater are obtained. [ABSTRACT FROM AUTHOR]

The distributed backup power source is vitally important under emergency conditions. Micro combustion powered thermoelectric generator (μ-CPTEG) is a promising candidate as a distributed backup power source. This study innovatively designed an all-in-one configuration to develop an efficient, standalone, and silent μ-CPTEG. The newly proposed all-in-one configuration organically integrates air-preheating, fuel premixing, low-noise combustion, efficient heat collection, and smooth heat compensation and spreading. Such an all-in-one configuration creates a standalone μ-CPTEG with an overall efficiency greater than 4.2 %, which is much larger than those in previous standalone μ-CPTEGs. The present μ-CPTEG incorporates 8 TE modules, and generates an electric power of 53.2 W with a running sound pressure level of 48 dB. Such performance indicates that the average electric power per TE module reaches 6.65 W, corresponding to a TE potential release level of 80.7 % systematically. The overall efficiency, as well as the efficiency of heat recovery, combustion, heat collection, TE and combined heat and power, are explored in detail. Comprehensive discussions are conducted to uncover the dense fog of releasing the TE potential at a systematic level in an μ-CPTEG. The present study provides a concrete method to develop a powerful, standalone, and silent μ-CPTEG. • Powerful, standalone, and silent μ-CPTEG is developed by a new technical framework. • An electric power of 53.2 W with an overall efficiency of 4.2 % is generated. • The running sound pressure level is 48 dB. • The performance is much better than previous standalone μ-CPTEGs. • The energy conversion density of propane by the μ-CPTEG reaches 271 Wh/kg. [ABSTRACT FROM AUTHOR]

The evaluation of energy efficiency improvements in polyisoprene footwear production is shown. By installing air preheater, combustion air natural gas consumption is reduced by 7%. Simultaneously, the boiler outlet flue gases' temperature is decreased from 204 °C to 66.93 °C, providing a sound basis for both economical savings and energy efficiency improvements, as well as ecological benefits to the environment. The application of condensate heat recovery resulted in flue gases' volume decreasing by 11.85% and a thermal pollution decrease of 91.34%. Combining air preheating by exhaust flue gases and condensate heat recovery resulted in a decrease in the flue gases' volume by 17.97%, and in the temperature lowering to 66.93 °C. The energy consumption for a combined system on location φ = 45 ° 49 ′ ) with a collector field of 12.936   ×   10 3   m 2 was investigated. The hybrid system was calculated for four variants: (1) solarized process without flue gases' heat recovery, (2) solarized processes with heat contend in flue gases using an air preheater, (3) solarized processes with condensate heat recovery, and (4) solarized processes with heat contend in flue gases using air preheater and condensate heat recovery. The highest fuel savings were shown in solarized processes with heat contend in flue gases using air preheater and condensate heat recovery, resulting in savings of up to 78.92%, while the flue gases' volume decreased from 5390.95   m 3 FG / h to 932.12   m 3 FG / h . [ABSTRACT FROM AUTHOR]

The corrosion phenomenon is considered the main problems for air preheater in thermal power plant. The boiler flue gas contamination leads to decrease the air preheater performance and increases the maintenance cost, which causes the degradation of the cold end heating elements and thus leads to decrease the heat recovery rate. In this study, an experimental investigation was done for the transient thermal behavior and the pressure drop of the standard regenerative air preheater (Pmatrix) model, evaluating the performance factor, then modifying the air preheater (P+CG) model by changing the plates at the cold end last basket to the coarse gravel media. Since the gravel media have low thermal conductivity and predicted to give a high pressure drop, a new technique was done for the modified air preheater to compensate the low heat transfer rates and reduce the pressure drop in the gravel media by inserting bypass tubes at ratios (i and s), Which, the (i) model represents the inner aperture of tubes for the hot baskets facing to the inner aperture of tubes for the cold basket. While (s) model the insertion the tubes of the hot baskets as a staggered distribution with the tubes for the cold basket. The experimental investigation was carried out for the Reynolds number based on the test duct hydraulic diameter at a range of 24500

The heating furnace of residue hydrogenation unit has the problems, such as high excess oxygen content, large fluctuation of oxygen content in radiation chamber, high concentration of NO% in exhaust gas, high exhaust gas temperature and low thermal efficiency. To solve the above problems, a comprehensive transformation of the hating furnace system is carried out. Adding an advanced process controller, the fluctuation of negative pressure and oxygen content of the heating furnace are significantly reduced, making the operation of the heating furnace more stable. Replacing the low nitrogen burner, the mass concentration of NOx in the discharged flue gas is reduced from 80.43 mg/m³ to 24.66 mg/m³, which is far lower than the national emission standard (100 mg/m³). Upgrading the heat pipe air preheater to a steel pate and cast iron plate combined air preheater, the flue gas temperature in summer is reduced from more than 130 °C to about 115 °C, and the thermal efficiency of the heating furnace increases significantly. After a series of transformation, the operation indexes of the heating furnace of the residue hydrogenation unit have been greatly improved, and the transformation purpose of energy conservation and environmental protection has been achieved. [ABSTRACT FROM AUTHOR]

This paper proposes a clustering framework with updating strategy in data stream for working condition classification and monitoring in a power plant air preheater system. A weight factor is added into the basic entropy fuzzy clustering method (EFC) for the statistical characteristics. Moreover, a framework is proposed to deal with data stream with updating block and off-line block. Four real-life data sets from UCI Machine Leaning Repository are adopted to evaluate the effectiveness (outlier detection rate and false alarm rate) of data mining framework with weighted EFC (W-EFC). These experiment results verify that the proposed framework dealing with data stream based on W-EFC has high clustering capacity and decrease noise data influence to a certain extent. Then, a field data set of the air preheater system is obtained for power plant application analysis. The clustering results can represent different working conditions and different working levels during long running time and thus can be taken as guidance for real-time operation monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The growing production of greenhouse gases and fossil fuels price obligated decision-makers in communications to implement energy sources more efficiently. The greenhouses have been developed through the years for the safe production of food sources. Thermal energy devotes a large portion of energy need in greenhouses. In developing countries, the rate of fuel consumption in the greenhouse is high, and there is an urgent need for improving heating systems. Here the possibility of reusing and storing the waste heat by phase change material (PCM) in a sample greenhouse studied experimentally. The PCM heat recovery system (PCM HRS) is a 20 c m × 50 c m × 140 c m plate type heat exchanger where the plates are replaced with PCM plate containers. The charge and discharge of the system are performed in two separate sections. The discharge stage organized in two separate schemes: delivering the stored heat directly inside the greenhouse space and using stored heat to preheat the combustion air of the burner. The heating system analyzed from the viewpoint of energy and the results show that the effect of preheating the heater air gives rise to a 23.7% reduction of gas consumption and the effect is much more pronounced compared to the direct using of the stored heat. Also, the resulted energy saving obtained by using the PCM HRS returns the initial investment within four months. • The application of waste heat recovery and phase change material in a greenhouse studied experimentally. • Two approaches are used to recover the stored waste heat. • Preheating the air heater resulted to 20% higher energy efficiency. • The payback period of retrofitting greenhouse is 4 months. • Retrofitting the greenhouse would be very economical by governmental financial support. [ABSTRACT FROM AUTHOR]

The corrosion phenomenon is considered the main problems for air preheater in thermal power plant. The boiler flue gas contamination leads to decrease the air preheater performance and increases the maintenance cost, which causes the degradation of the cold end heating elements and thus leads to decrease the heat recovery rate. In this study, an experimental investigation was done for the transient thermal behavior and the pressure drop of the standard regenerative air preheater (Pmatrix) model, evaluating the performance factor, then modifying the air preheater (P+CG) model by changing the plates at the cold end last basket to the coarse gravel media. Since the gravel media have low thermal conductivity and predicted to give a high pressure drop, a new technique was done for the modified air preheater to compensate the low heat transfer rates and reduce the pressure drop in the gravel media by inserting bypass tubes at ratios (i and s), Which, the (i) model represents the inner aperture of tubes for the hot baskets facing to the inner aperture of tubes for the cold basket. While (s) model the insertion the tubes of the hot baskets as a staggered distribution with the tubes for the cold basket. The experimental investigation was carried out for the Reynolds number based on the test duct hydraulic diameter at a range of 24500matrix) model. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 3.6 Mt/a medium pressure hydrocracking unit of CNOOC Huizhou Petrochemical Co., Ltd. has long had problems of high exhaust gas temperature and low heating furnace efficiency. It is concluded that the dew point corrosion of the flue gas can be avoided by controlling the exhaust temperature of the air pre-heater above 90 °C. The exhaust gas temperature of current working condition is higher than 150 °C. Therefore, the heating furnace thermal efficiency can be improved by lowering the exhaust temperature. Since the glass tube module is used in the low temperature section, the risk of dew point corrosion is reduced, and the modular design reduces the maintenance frequency and saves the maintenance costs. It is proposed that the original heat pipe heat exchanger be transformed into a combined air preheater of plate type and glass tube module. After the renovation, the exhaust gas temperature at the outlet of the air preheater is reduced by 50, the preheated air temperature is increased by 80 °C, the thermal efficiency of each heating furnace is increased by about 2 percentage point, the fuel gas is saved by 150 m /h, the operating cost is saved by 4 million yuan per year, and the maintenance cost is saved by 200 000 yuan per cycle. The energy-saving effect of the retrofitted device is remarkable. [ABSTRACT FROM AUTHOR]

This study designed and tested the components of hot balance of plant (BoP) included in a 2 kW‐class solid oxide fuel cell (SOFC) system and evaluated their thermal performance. A Pd/Pt catalytic combustor was fabricated as a component of hot BoP, and integrated hot BoP with an efficient structure was fabricated by calculating the heat transfer rates of the air preheater and steam generator through a theoretical design method. It was found that placement of the air preheater in front of the steam generator exhibited the most excellent heat transfer rate. Moreover, the heat transfer rates of the designed air preheater and steam generator exceeded the upper limit of the maximum possible heat transfer of the preheated air and the water. In experimental results, the thermal efficiency of the integrated system was 60% at the reference heat input and 70% at low heat input. The oxidizing flame of the catalyst was visualized, and the oxidation characteristics of the catalytic combustor were analyzed by measuring the concentration of the final discharged gas, that is, carbon monoxide (CO). This study helps to fabricate the integrated hot BoP system, as it provides design techniques and efficient system configuration. [ABSTRACT FROM AUTHOR]

Highlights • Three-dimensional numerical simulation of air preheater is presented. • The numerical model is validated against experimental data. • Three-dimensional temperature distribution of fluid and heating surface is obtained. • The low-temperature corrosion is mainly occurred in the hot end of flue gas channel. Abstract To overall control the wall temperature of rotary quad-sectional air preheater and ensure the safety of boiler units, it is important to research its three-dimensional temperature field. Computational fluid dynamics method (CFD) is used to simulate the heat transfer performance of a 300 MW circulating fluidized bed (CFB) boiler. The temperature of rotor heating surface is defined as user-defined scalar (UDS) to solve scalar equation. Numerical results which are validated by experimental data present the essential parameters such as three-dimensional temperature, heat flux and heat transfer distribution of both working fluid and heating surface. The temperature difference between working fluid and heating surface, heat transfer quantity per unit volume are also obtained. Numerical results show that the different materials and types of heating surface will cause the differences in heat transfer performance between cold end and hot end. The temperature of working fluid are different between cold end and hot end, resulting in volume flow changing to make the scouring velocity different. That is the structural reason for the distinctions in heat transfer performance. It is concluded that low-temperature corrosion mainly occurs in the heating surface at the inlet of hot end in flue gas channel, where the metal temperature need to be kept above acid dew point so as to retard the low-temperature corrosion. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a comprehensive approach for optimization of soot-blowing of air preheaters in a coal-fired power plant boiler. In the method, modeling of the cleanliness factor is firstly proposed to monitor the ash deposition status of the air preheaters. Then, the statistical fitting of the ash fouling status is subsequently obtained to analyze the ash fouling dynamics and assessment of optimized soot-blowing strategies. Soot-blowing strategies are finally developed to optimize the steam consumption and heat transfer efficiency. Our methods can achieve the fouling monitoring and soot-blowing optimization of air preheater (APH) by using the existing monitoring data, not requiring additional special instruments and complex computing systems. The methodology is validated with the actual operating data of a 300 MW coal-fired power plant boiler. The results show the effectiveness of the proposed method. It can be used for the soot-blowing optimization in most coal-fired power plant boiler with air preheaters.