• Title/Summary/Keyword: Plant Operation & Maintenance

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A Study on Operating Method to Save Energy from the Adsorption Dryer in the Process of Purifying Compressed Air (고순도 압축공기 제조시스템의 흡착식 Dryer에서 에너지절감을 위한 운전방법에 관한 연구)

  • Kang, Seok-Wan;Chang, Sung-Ho;Kim, Hyeon-Joon;Kim, Sung-Soo;Lee, Yeong-Wook
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.39 no.3
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    • pp.180-191
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    • 2016
  • Optimizing energy usage for maximum efficiency is an essential goal for manufacturing plants in every industrial manufacturing sector. The generation and distribution of purifying compressed air is a large expense incurred in practically all manufacturing processes. Not only is the generation and treatment expensive equipment of compressed air, but frequent maintenance and effective operation is also required. As a plant's compressed air system is often an integral part of the production process, it needs to be reliable, efficient, and easy to be maintain. In this paper, we study to find operating method to save energy from the adsorption dryer in the process of purifying compressed air, which is required for a clean room production site in "A" company. The compressed air passes through a pressure vessel with two "towers" filled with a material such as activated alumina, silica gel, molecular sieve or other desiccant material. This desiccant material attracts the water from the compressed air via adsorption. As the water clings to the desiccant, the desiccant particle becomes saturated. Therefore, Adsorption dryer is an extremely significant facility which removes the moisture in the air $70^{\circ}C$ below the dew point temperature while using a lot of energy. Also, the energy consumption of the adsorption dryer can be varied by various operating conditions (time, pressure, temperature, etc). Therefore, based on existing operating experiments, we have searched operating condition to maximize energy saving by changing operating conditions of the facility. However, due to a short experiment period (from September to October), further research will be focused on considering seasonality.

Economic Feasibility Study for Commercial Production of Bio-hydrogen (해양바이오수소개발 사업의 상업생산을 위한 예비경제성평가)

  • Park, Se-Hun;Yoo, Young-Don;Kang, Sung Gyun
    • Ocean and Polar Research
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    • v.38 no.3
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    • pp.225-234
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    • 2016
  • This project sought to conduct an economic feasibility study regarding the commercial production of bio-hydrogen by the marine hyperthermophilic archaeon, Thermococcus onnurineus NA1 using carbon monoxide-containing industrial off-gas. We carried out the economic evaluation of the bio-hydrogen production process using the raw material of steel mill by-product gas. The process parameter was as follows: $H_2$ production rate was 5.6 L/L/h; the conversion of carbon monoxide was 60.7%. This project established an evaluation criterion for about 10,000 tonne/year. Inflation factors were considered as 3%. The operating costs were recalculated based on prices in 2014. The total investment required for development was covered 30% by capital and 70% by a loan. The operation cost for the 0.5-year test and integration, and the cost for the first three months in the 50% production period were considered as the working capital in the cost estimation. The costs required for the rental of office space, facilities, and other related costs from the construction through to full-scale production periods were considered as continuing expenses. Materials, energy, waste disposal and other charges were considered as the operating cost of the development system. Depreciation, tax, maintenance and repair, insurance, labor, interest rate charges, general and administrative costs, lubrication and miscellaneous expenses were also calculated. The hydrogen price was set at US$ 4.15/kg for the economic evaluation. As a result, the process was considered to be economical with the payback period of 6.3 years, NPV of 18 billion Won and IRR of 26.7%.

Estimation of the Number of Physical Flaws Using Effective POD (유효 POD를 이용한 물리적 결함 수의 추정)

  • Lee, Jae-Bong;Park, Jae-Hak;Kim, Hong-Deok;Chung, Han-Sub
    • Journal of the Korean Society of Safety
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    • v.21 no.4 s.76
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    • pp.42-48
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    • 2006
  • The strategies of maintenance and operation are usually established based on the number of flaws and their size distribution obtained from nondestructive inspection in order to preserve safety of the plant. But non destructive inspection results are different from the physical flaws which really exist in the equipments. In case of a single inspection, it is easy to estimate the number of physical flaws using the POD curve. However, we may be faced with some difficulties in obtaining the number of physical flaws from the periodic in-service non destructive inspection data. In this study a simple method for estimating the number of physical flaws from periodic in-service nondestructive inspection data was proposed. In order to obtain the flaw growth history, the flaw growth was simulated using the Monte Carlo method and the flaw size and the corresponding POD value were obtained for each flaw at each periodic inspection time. The flaw growth rate used in the simulation was statistically calculated from the in-service inspection data. By repeating the simulation numerous flaw growth data could be generated and the effective POD curve was obtained as a function of flaw size. From the effective POD curve the number of physical flaws was obtained. The usefulness and convenience of the proposed method was evaluated from several applications and satisfactory results were obtained.

Prevention of Insulation Damage Layer and Shell Corrosion in Thermal Storage Tanks for District Heating (지역난방용 축열조의 단열재 손상과 외각부식 개선방안)

  • Bang, Yong-Eoon;Yoo, Ho-seon
    • Plant Journal
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    • v.10 no.4
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    • pp.35-41
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    • 2014
  • The height and capacity of the thermal storage tank can be decided by the altitude and heat load of the heat supply area. Evaporation in heat pipe can be prevented by pressurizing it with the hydraulic head of the thermal storage tank. In addition, it absorbs the expanded volume from the temperature changes and supplies water to the pipelines in case of the shortage of water. One of the most important roles of the thermal storage tank is a stable heat supply facility. It can control the heat demand by accumulating the surplus heat and supplying in changing heat demand time. The purpose of this thesis is to be helpful for the operation and maintenance of the thermal storage tanks. The study has been carried out for 18 thermal storage tanks, which have been used polyurethane foam as insulation, among 27 tanks in district heating plants. The characteristics of the insulation materials, the reasons for the damages of the insulation and how impact the insulation damages to the corrosion of the thermal storage tank have been studied.

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Methodology of Engine Fitness Diagnosis Using Variation of Crankshaft Angular Speed (엔진 회전속도 변화를 이용한 상태진단 기법에 관한 연구)

  • Lee, Byung-Yeol;Ha, Seung-Jin;Lim, Ock-Taeck
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.11
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    • pp.1529-1535
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    • 2011
  • Improvement of the thermal efficiency in operation and maintenance of low- and medium-speed engines is a kind of never-ending requirement in the maritime power plant business. For the purpose of improving engine management efficiency, a principal factor that represents the fitness of the engine should be identified. Gas pressure, gas temperature, and vibration have all been used as this factor. However, they have limitations in terms of response speed and diagnosis accuracy. The EFR (engine fitness ratio) is suggested as a new diagnostic factor in this paper. The EFR is defined as the ratio of particular frequencies in the frequency domain and represents the fitness of an engine. It is calculated from the fluctuation pattern of the crankshaft angular speed. The EFR was verified using an experimental method for a low-speed engine and an analytic method for a medium-speed engine.

침지형 분리막을 사용한 오수처리

  • 최광호
    • Proceedings of the Membrane Society of Korea Conference
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    • 1998.06a
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    • pp.113-133
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    • 1998
  • In activated sludge process, sludge settling condition is affected by organic loading rate or operation condition, and if settling condition is getting worse, it is common that overall process fails due to wash-out of biomass causing low concentration in the aeration tank. Also activated sludge process has such several problems as requiring large area, consuming a lot of power and producing large volume of sludge. Increased public concern over health and the environment combined with a strong desire to reduce capital, operating and maintenance costs, have created a need for innovative technologies for building new high quality effluents which vail meet 21st century crkeria. MBR(Membrane Bioreactor) process consists of a biological reactor and ultrafiltration(UF) membrane system that replaces the conventional clarifier of an activated sludge process. The main operating advantages of this system are that the quality of the effluent is independent of the settleability of the mixed liquor and that the effluent is free of suspended solids in any operating condition. It is possible to eliminate clarifier and to reduce the volume of aeration tank because it can afford to accumulate high biomass concentration in the bioreactor(20, 000~30, 000mg/L), which would not be possible in a conventional activated sludge process. Therefore, this process reduces overall treatment plant area. In addition to those advantages, Longer SRT condition enables higher sludge digestion in MBR process so the sludge volume produced is 50 to 70% lower than that of conventional activated sludge process There are two kinds of MBR process according to the allocations of membrane. One is cross flow type MBR of which module is located outside of the bioreactor and mixed liquor is driven into the membrane module. The other is submerged type MBR process of which module is submerged in the bioreactor and mixed liquor is generally sucked from the lumen side. addition to that the cake layer is often removed by the uplifting flow of bubbling air. A submerged MBR process is superior to a crossflow MBR in regard to the power consumption because suction pressure of a submerged MBR is generally lower than that of a crossflow MBR which has recirculation pump. A submerged MBR, therefore, has the potential to be applied to small wastewater treatment plants that need low cost treatment systems.

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Analysis of Dominant Microorganisms of Bulking Sludge at Low Dissolved Oxygen Concentration using 16S rRNA Sequences (16S rRNA 염기서열을 이용한 낮은 용존산소농도에서 발생한 벌킹슬러지의 우점종 분석)

  • Kim, Yun-Jung;Park, Eun-Hye;Kim, Gyu-Dong;Nam, Kyoungphile;Chung, Tai Hak
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.506-511
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    • 2004
  • Maintaining dissolved oxygen (DO) at sufficiently low concentration in the aeration tank at a wastewater treatment plant (WWTP) is essential for reduction of the costs of operation and maintenance. On the other hand, the low DO level may result in adverse effect on the integrity of the activated sludge, A typical and disastrous outcome frequently experienced is the outgrowth of filamentous microorganisms, which is called as filamentous bulking, In addition to the traditional methods such as sludge settleability and microscopic observation of the culture, molecular techniques including polymerase chain reaction (PCR) amplification followed by 16S rRNA sequencing were applied to identify filamentous bacteria present in bulking sludge under a condition of low DO concentration, Two morphologically distinct groups, presumably consisting of Sphaerofilus nafans, and Eikelboom Type 1701 or Type 1851, were identified through microscopic observation. They were further confirmed by subsequent 16S rRNA sequencing. Dominant filamentous bacteria identified by the molecular techniques were consisted of three major groups. Sequences of partial 16S rRNA cloned showed that the filamentous bulking organisms were closely related to Eikelboom Type 021N and Eikelboom Type 1701, and Sphaerotilus natans, respectively. Molecular methods were found to possess a strong potential of direct examination of the microbial community of an activated sludge system.

Development of artificial neural network based modeling scheme for wind turbine fault detection system (풍력발전 고장검출 시스템을 위한 인공 신경망 기반의 모델링 기법 개발)

  • Moon, Dae Sun;Ra, In Ho;Kim, Sung Ho
    • Smart Media Journal
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    • v.1 no.2
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    • pp.47-53
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    • 2012
  • Wind energy is currently the fastest growing source of renewable energy used for electrical generation around world. Wind farms are adding a significant amount of electrical generation capacity. The increase in the number of wind farms has led to the need for more effective operation and maintenance procedures. Condition Monitoring System(CMS) can be used to aid plant owners in achieving these goals. In this work, systematic design procedure for artificial neural network based normal behavior model which can be applied for fault detection of various devices is proposed. Furthermore, to verify the design method SCADA(Supervisor Control and Data Acquisition) data from 850kW wind turbine system installed in Beaung port were utilized.

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AN ANALYSIS OF TECHNICAL SECURITY CONTROL REQUIREMENTS FOR DIGITAL I&C SYSTEMS IN NUCLEAR POWER PLANTS

  • Song, Jae-Gu;Lee, Jung-Woon;Park, Gee-Yong;Kwon, Kee-Choon;Lee, Dong-Young;Lee, Cheol-Kwon
    • Nuclear Engineering and Technology
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    • v.45 no.5
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    • pp.637-652
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    • 2013
  • Instrumentation and control systems in nuclear power plants have been digitalized for the purpose of maintenance and precise operation. This digitalization, however, brings out issues related to cyber security. In the most recent past, international standard organizations, regulatory institutes, and research institutes have performed a number of studies addressing these systems cyber security.. In order to provide information helpful to the system designers in their application of cyber security for the systems, this paper presents methods and considerations to define attack vectors in a target system, to review and select the requirements in the Regulatory Guide 5.71, and to integrate the results to identify applicable technical security control requirements. In this study, attack vectors are analyzed through the vulnerability analyses and penetration tests with a simplified safety system, and the elements of critical digital assets acting as attack vectors are identified. Among the security control requirements listed in Appendices B and C to Regulatory Guide 5.71, those that should be implemented into the systems are selected and classified in groups of technical security control requirements using the results of the attack vector analysis. For the attack vector elements of critical digital assets, all the technical security control requirements are evaluated to determine whether they are applicable and effective, and considerations in this evaluation are also discussed. The technical security control requirements in three important categories of access control, monitoring and logging, and encryption are derived and grouped according to the elements of attack vectors as results for the sample safety system.

Study on Artificial Neural Network Based Fault Detection Schemes for Wind Turbine System (풍력발전 시스템을 위한 인공 신경망 기반의 고장검출기법에 대한 연구)

  • Moon, Dae-Sun;Kim, Sung-Ho
    • Journal of the Korean Institute of Intelligent Systems
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    • v.22 no.5
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    • pp.603-609
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    • 2012
  • Wind energy is currently the fastest growing source of renewable energy used for electrical generation around world. Wind farms are adding a significant amount of electrical generation capacity. The increase in the number of wind farms has led to the need for more effective operation and maintenance procedures. Condition Monitoring System(CMS) can be used to aid plant owners in achieving these goals. Its aim is to provide operators with information regarding the health of their machines, which in turn, can help them improve operational efficiency. In this work, systematic design procedure for artificial neural network based normal behavior model which can be applied for fault detection of various devices is proposed. Furthermore, to verify the design method SCADA(Supervisor Control and Data Acquisition) data from 850KW wind turbine system installed in Beaung port were utilized.