• Title/Summary/Keyword: Reactor Operating Condition

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Study on the Relationship between Weather Conditions, Sewage and Operational Variables of WWTPs using Multivariate Statistical Methods (기상조건이 하수발생량 및 하수처리장 운전인자에 미치는 영향에 관한 통계적 분석)

  • Lee, Jae-Hyun
    • Journal of Korean Society on Water Environment
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    • v.28 no.2
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    • pp.285-291
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    • 2012
  • Generally, the rainfall and the influent of wastewater treatment plants (WWTPs) have strong relationship at the case of combined sewers. With the fact that the influent variations in terms of quantity and sewage quality is the most common and significant disturbance, the impact factor to the characteristics of sewage should be searched for. In this paper, the relationship between weather conditions such as humidity, temperature and rainfall and influent flowrate and contaminant concentration was analysed using factor analysis. Additionally, 3 influent types were deduced using cluster analysis and the distributions of operational variables were compared to the each groups by one-way ANOVA. The applied dataset were clustered to three groups that have the similar weather and influent conditions. These different conditions can cause the different operating conditions at WWTPs. That is, the Group 1 is for the condition with high humidity and rainfall, so DO concentration in the reactor was very high but MLSS concentration was very low because of too large flowrate. However, the Group 3 is classified to the case having low humidity, temperature, and rainfall, therefore, the SRT was the longest and the SVI was the highest due to the worst settleability in the winter for a year.

Water Treatment Characteristics by Foam Separator According to Operation Parameters (포말분리공정의 운전인자 변화에 따른 수처리 특성)

  • 허현철;김성구
    • Journal of Life Science
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    • v.8 no.5
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    • pp.504-508
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    • 1998
  • A study was conducted to evaluate a protein removal characteristics by foam separation. The foam separator was operated in well-mixed tank which would be considered as a completely mixed condition. The feasibility of foam separation to remove protein from fresh and sea water was investigated. Protein removal characteristics of the foam separator were obtained by batch reactor operations. To find the effect of the operating parameter to protein removal rate, the foam separation was carried with variation of initial protein concentration and foam height. The results indicated that the protein removal efficiency was increased with increasing protein concentration and decreased with increasing foam height. The relationship between protein concentration and protein removal rate was evaluated by linear regression.

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A Procedure for Statistical Thermal Margin Analysis Using Response Surface Method and Monte Carlo Technique (반응 표면 및 Monte Carlo 방법을 이용한 통계적 열여유도 분석 방법)

  • Hyun Koon Kim;Young Whan Lee;Tae Woon Kim;Soon Heung Chang
    • Nuclear Engineering and Technology
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    • v.18 no.1
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    • pp.38-47
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    • 1986
  • A statistical procedure, which uses response surface method and Monte Carlo simulation technique, is proposed for analyzing the thermal margin of light water reactor core. The statistical thermal margin analysis method performs the best.estimate thermal margin evaluation by the probabilistic treatment of uncertainties of input parameters. This methodology is applied to KNU-1 core thermal margin analysis under the steady state nominal operating condition. Also discussed are the comparisons with conventional deterministic method and Improved Thermal Design Procedure of Westinghouse. It is deduced from this study that the response surface method is useful for performing the statistical thermal margin analysis and that thermal margin improvement is assured through this procedure.

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Development of a Compact Nuclear Hydrogen Coupled Components Test Loop (원자로수소생산을 위한 연결부품 실험용 소형 컴팩트 실험장치 개발)

  • Hong, S.D.;Kim, J.H.;Kim, C.S.;Kim, Y.W.;Lee, W.J.
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2850-2855
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    • 2008
  • Very High Temperature Reactor (VHTR) has been selected as a high energy heat source for a nuclear hydrogen generation. The VHTR heat is transferred to a thermo-chemical hydrogen production process through an intermediate loop. Both Process Heat Exchanger and sulfuric acid evaporator provide the coupled components between the VHTR intermediate loop and hydrogen production module. A small scaled Compact Nuclear Hydrogen Coupled Components test loop is developed to simulate the VHTR intermediate loop and hydrogen production module. Main objective of the loop is to screening the candidates of NHDD (Nuclear Hydrogen Development and Demonstration) coupled components. The operating condition of the gas loop is a temperature up to $950^{\circ}C$ and a pressure up to 6.0MPa. The thermal and fluid dynamic design of the loop is dependent on the structures that enclose the gas flow, especially primary side that has fast gas velocity. We designed and constructed a small scale sulfuric acid experimental system which can simulate a part of the hydrogen production module also.

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Numerical Comparison of Thermalhydraulic Aspects of Supercritical Carbon Dioxide and Subcritical Water-Based Natural Circulation Loop

  • Sarkar, Milan Krishna Singha;Basu, Dipankar Narayan
    • Nuclear Engineering and Technology
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    • v.49 no.1
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    • pp.103-112
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    • 2017
  • Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

A Compensation Method considering Unbalance of Reactor at Source Side in Driving 3 Phase Voltage type PWM Converter (3상 전압형 PWM 컨버터 운전시 전원측 리액터의 불평형을 고려한 보상법)

  • Chun, Ji-Yong;Lee Sa-Young;Cho Yu-Hwan;Lee Geun-Hong
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.4
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    • pp.373-379
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    • 2005
  • In this paper, the control algorithm of DC source device for inverter starting is proposed and the control method for compensating unbalance system source on operating time in the voltage type PWM converter with driving and regenerative faculty is suggested. The maintaining way of balancing condition for converter of AC source is used the compensating unbalanced status by current control loop. Because it is possible that the unbalanced System control is used to leakage transformer not equaled reactance by each phase in rectifier system, the proposed H/W and control algorithm of rectifier system is contributed to minimize of device and rising efficiency.

Disinfection effect and formation characteristics of disinfection by-product at the Electrolyzed Water (전기분해수 살균효과 및 소독부산물 생성 특성 평가)

  • Cho, Youngman
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.5
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    • pp.547-554
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    • 2013
  • Chlorine has strong oxidizing power, also it is many advantages over other disinfectants such as the residual characteristic and economic feasibility. However, chlorine also has disadvantages such as creating disinfection by-products of chlorine as THMs. In particular, the most deadly disadvantage of chlorine is that it is extremely poisonous toxins about all alive lives. Disinfection with electrolysis water can be a very useful way Because you do not have to worry about chlorine's dangerous. In this study, we evaluated the potential as a disinfectant, across the evaluating disinfection effect and generating characteristic of by-products. The electrolyzed water could be obtained removal efficiencies of over 99.9 % the coliform by operating condition such as residence time, current density (voltage), the electrode gap. The residual chlorine be generated 10,000 mg/L in current density $1.0A/dm^2$ and residence time of 10 minutes. The residual chlorine concentration was possible to maintain a stable. The by-products generated by high concentration residual chlorine in the reactor such as trihalomethanes, haloaceticacid, chloralhydrate, haloacetonitrile were detected in less than a water quality standards. At the concentration of less than residual chlorine of 1 ppm, the chlorine disinfection by-products be generated most below the detection limit.

The Implementation of Current Compensation Controller in Driving Voltage type Converter considering the Unbalance of Reactor at the Source Side (전원측 리액터 불평형을 고려한 전압형 컨버터의 전류 보상 제어기 구현)

  • Chun Ji-Yong;Cho Yu-Hwan;Lee Geun-Hong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.5 no.5
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    • pp.413-420
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    • 2004
  • In this paper, the control algorithm of DC source device for inverter starting is proposed and the control method for compensating unbalance system source on operating time in the voltage type PWM converter with driving and regenerative faculty is suggested. The maintaining method of balancing condition for converter of AC source is used the compensating unbalanced status by current control loop. In order to solve the problem which the unbalanced system control is used to leakage transformer not equaled reactance by each phase in rectifier system. The proposed H/W and control algorithm of rectifier system is contributed to minimize of device and rising efficiency.

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Prediction of critical heat flux for narrow rectangular channels in a steady state condition using machine learning

  • Kim, Huiyung;Moon, Jeongmin;Hong, Dongjin;Cha, Euiyoung;Yun, Byongjo
    • Nuclear Engineering and Technology
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    • v.53 no.6
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    • pp.1796-1809
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    • 2021
  • The subchannel of a research reactor used to generate high power density is designed to be narrow and rectangular and comprises plate-type fuels operating under downward flow conditions. Critical heat flux (CHF) is a crucial parameter for estimating the safety of a nuclear fuel; hence, this parameter should be accurately predicted. Here, machine learning is applied for the prediction of CHF in a narrow rectangular channel. Although machine learning can effectively analyze large amounts of complex data, its application to CHF, particularly for narrow rectangular channels, remains challenging because of the limited flow conditions available in existing experimental databases. To resolve this problem, we used four CHF correlations to generate pseudo-data for training an artificial neural network. We also propose a network architecture that includes pre-training and prediction stages to predict and analyze the CHF. The trained neural network predicted the CHF with an average error of 3.65% and a root-mean-square error of 17.17% for the test pseudo-data; the respective errors of 0.9% and 26.4% for the experimental data were not considered during training. Finally, machine learning was applied to quantitatively investigate the parametric effect on the CHF in narrow rectangular channels under downward flow conditions.

Performance Evaluation of Tertiary Post-denitrification Processes for the Reuse of Secondary Effluent from Wastewater Treatment Plant (하수2차처리수의 재이용을 위한 후탈질공정의 평가)

  • Lee, Chanho;Yun, Zuwhan;Yi, Yun Seok;Lee, Han Saem;Ahn, Dong Keun
    • Journal of Korean Society on Water Environment
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    • v.23 no.5
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    • pp.642-649
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    • 2007
  • The effectiveness of add-on tertiary treatment processes for the polishing of the effluent of a biological nutrient removal (BNR) system from a modified $A^2/O$ process has been examined under the field condition with pilot-scale plants. The add-on treatment processes of 1) combined biofilm anoxic reactor and sand filtration, and 2) two-stage denitrification filter had been operated with various operating conditions. The experimental results indicated that two-stage denitrification filter could produced a better polished tertiary effluent. Filtration rate of $150m^3/m^2{\cdot}d$ for the 2-stage denitrifying filter could decrease the nitrate removal probably due to shorter detention time that caused insufficient reaction for denitrification. Two stage denitrification filter operated with M/N ratio of 3.0 and filtration rate of $100m^3/m^2{\cdot}d$ produced the tertiary effluent with nitrate and SS concentraitons of 2.8 mg/L and 2.3 mg/L, respectively. When the operating temperature reduced $30^{\circ}C$ to $18^{\circ}C$, $NO_3{^-}-N$ removal efficiency decreased from 73% to 68%.