• Membrane and Water Treatment
• /
• 제9권2호
• /
• pp.129-136
• /
• 2018

In this contribution, the control of multivariable reverse osmosis (RO) desalination plant using proportional-integral-derivative (PID) controllers is presented. First, feed-forward compensators are designed using simplified decoupling method and then the PID controllers are tuned for flux (flow-rate) and conductivity (salinity). The tuning of PID controllers is accomplished by minimization of the integral of squared error (ISE). The ISEs are minimized using a recently proposed algorithm named as teacher-learner-based-optimization (TLBO). TLBO algorithm is used due to being simple and being free from algorithm-specific parameters. A comparative analysis is carried out to prove the supremacy of TLBO algorithm over other state-of-art algorithms like particle swarm optimization (PSO), artificial bee colony (ABC) and differential evolution (DE). The simulation results and comparisons show that the purposed method performs better in terms of performance and can successfully be applied for tuning of PID controllers for RO desalination plants.

• Environmental Engineering Research
• /
• 제14권1호
• /
• pp.19-25
• /
• 2009

In this study, total bacteria, enteric members of the $\gamma$-proteobacteria, and microbial communities in seawater were analyzed as indirect indicators for quantifying biofouling. Biomass in seawater can significantly affect feed water pretreatment and membrane biofouling of reverse osmosis desalination processes. The purpose of this paper is to investigate microbiological quantity and quality of seawater at the potential intake of a desalination plant. For this analysis, the total direct cell count (TDC) using 4'-6-diamidino-2-phenylindole (DAPI)-staining and DNA-based real-time PCR were used to quantify the total bacteria and relative content of enteric members of $\gamma$-proteobacteria in seawater, respectively. In addition, microbial communities were examined using 16S rRNA gene cloning and bacterial isolation to identify the most abundant bacteria for a further biofouling study. The experimental results of this study identified about $10^6$ cells/mL of (total) bacteria, $10^5$ 16S rRNA gene copies/mL of enteric $\gamma$-proteobacteria, and the presence of more than 20 groups of bacteria.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권8호
• /
• pp.1185-1191
• /
• 2008

The core design technology for the multi-effect desalination plant using the thermo compressor (MED-TVC) was investigated by the performance test of multi effect desalination plant in this paper. The final G.O.R (gain of output ratio) of MED-TVC type desalination plant is strongly affected by the performance of thermo-vapor compressor. The present experiments for the desalinating capacity and G.O.R were obtained for the range of the motive steam pressure, 266.0, 250.0, 230.0 and 200.0 kPa. And as a practical problem, to investigate the influence of the sea water temperature to the G.O.R, the inlet steam temperature of the suction water vapor was changed in the range of $311.2{\sim}324.2$ K in the present experiment. Through the experiments, the maximum value of G.O.R was 8.5 at the condition of the motive steam pressure, 136.0 kPa and the minimum value of G.O.R was 8.1 at the condition of the motive steam pressure, 266.0 kPa. And it was confirmed that the range of desalination capacity was $355.2{\sim}264.0$ ton/day in the normal operation condition.

• 대한기계학회논문집 C: 기술과 교육
• /
• 제1권1호
• /
• pp.59-68
• /
• 2013

본 연구에서는 한외여과막과 역삼투압막으로 이루어진 해수담수화장치를 구성하였다. 해수를 취수하여 디스크필터와 한외여과막을 이용한 전처리설비를 통과시켜 생산한 전처리수의 $SDI_{15}$와 탁도를 측정하여 역삼투압해수담수설비에 적합함을 밝혔다. 역삼투압해수담수설비의 부산물인 브라인을 전처리수와 혼합하여 역삼투압해수담수설비의 입구농도를 변화시켰다. 농도 변화실험에서, 해수농도가 역삼투압해수담수설비의 성능에 끼치는 영향을 실험으로 구하였다. 염배제율, 회수율, 생산수의 수질은 입구농도에 따라 많은 변화가 있었으며, 에너지소비량도 입구농도에 거의 선형적으로 상승하는 것을 실험으로 구하였다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2016년도 추계학술대회
• /
• pp.663-664
• /
• 2016

해수를 이용한 온도차 발전은 심층수와 표층수의 온도 차이를 이용한 암모니아(냉매)를 사용하여 폐쇄적인 액화와 기화를 반복하여 터빈을 돌리는 방식이다. 온도차 발전의 특성상 온도 차이가 클수록 에너지 발전 특성은 좋아진다. 이는 심층수 표층수의 온도차이가 커야 됨을 이야기 한다. 하지만 겨울이 되면 표층수와 심층수의 온도차이가 크지 않아 에너지 효율이 떨어지는 문제점이 있다. 그리고 해수 담수화기술은 지구의 97%를 차지하지만 우리가 먹을 수 없는 바닷물을 담수로 바꾸는 기술로, 해수 담수화기술로 생산된 담수는 선박내의 공업, 식수 등 각종 용수로 사용할 수 있다. 본 논문에서는 현재 문제가 되고 있는 계절에 따른 표층수의 온도 변화를 개선하기 위해 기존에 사용하고 있는 선박용 디젤엔진의 열에너지와 LNG의 냉열 에너지를 사용한 온도차 발전을 위해 LNG 운송 선박을 기준으로 LNG 운송 선박 하이브리드 엔진에 관한 연구와 냉열 에너지를 활용한 해수 냉동법으로 담수화하는 발전 및 담수화를 복합시킨 연구를 제시하고자 한다.

• Nuclear Engineering and Technology
• /
• 제47권3호
• /
• pp.293-305
• /
• 2015

In this paper, we suggest the conceptual design of a water-cooled reactor system for a low-pressure inherent heat sink nuclear desalination plant (LIND) that applies the safety-related design concepts of high temperature gas-cooled reactors to a water-cooled reactor for inherent and passive safety features. Through a scoping analysis, we found that the current LIND design satisfied several essential thermal-hydraulic and neutronic design requirements. In a thermal-hydraulic analysis using an analytical method based on the Wooton-Epstein correlation, we checked the possibility of safely removing decay heat through the steel containment even if all the active safety systems failed. In a neutronic analysis using the Monte Carlo N-particle transport code, we estimated a cycle length of approximately 6 years under 200 $MW_{th}$ and 4.5% enrichment. The very long cycle length and simple safety features minimize the burdens from the operation, maintenance, and spent-fuel management, with a positive impact on the economic feasibility. Finally, because a nuclear reactor should not be directly coupled to a desalination system to prevent the leakage of radioactive material into the desalinated water, three types of intermediate systems were studied: a steam producing system, a hot water system, and an organic Rankine cycle system.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
• /
• pp.204-209
• /
• 2011

According to the environment report of UN, korea was classified as potable water shortage countries. Approximately 71% of the Earth's surface is covered by ocean. However, it is difficult to use for industry of residential purpose without a certain processing. The development of solar and waste-heat used absorption desalination technology have been examined as a viable option for supplying clean energy. In this study, the modelling of the main devices for solar and waste-heat used and adsorption desalination system was introduced. The design is divided into three parts. First, the evaporator for the vaporization of the top water is designed, and then the reactor for the adsorption and release of the steam is designed, followed by the condenser for the condensation of the fresh water is designed. In addition, new features based on the energy balance are also included to design absorption desalination system. In this basicresearch, One-bed(reactor) adsorption desalination plant that employ a low-temperature solar and waste energy was proposed and experimentally studied. The specific water yield is measured experimentally with respect to the time controlling parameters such as heat source temperatures, coolant temperatures, system switching and half-cycle operational times.

• 한국물환경학회지
• /
• 제37권6호
• /
• pp.442-448
• /
• 2021

Seawater desalination is a technology through which salt and other constituents are removed from seawater to produce fresh water. While a significant amount of fresh water is produced, the desalination process is limited by the generation of concentrated brine with a higher salinity than seawater; this imposes environmental and economic problems. In this study, characteristics of seawater from three different locations in South Korea were analyzed to evaluate the feasibility of crystallization to seawater desalination. Organic and inorganic substances participating in crystal formation during concentration were identified. Then, prediction and economic feasibility analysis were conducted on the actual water flux and obtainable salt resources (i.e. Na2SO4) using membrane distillation and energy-saving crystallizer based on multi-stage flash (MSF-Cr). The seawater showed a rather low salinity (29.9~34.4 g/L) and different composition ratios depending on the location. At high concentrations, it was possible to observe the participation of dissolved organic matter and various ionic substances in crystalization. When crystallized, materials capable of forming various crystals are expected. However, it seems that different salt concentrations should be considered for each location. When the model developed using the Aspen Plus modular was applied in Korean seawater conditions, relatively high economic feasibility was confirmed in the MSF-Cr. The results of this study will help solve the environmental and economic problems of concentrated brine from seawater desalination.

• Membrane and Water Treatment
• /
• 제2권3호
• /
• pp.147-158
• /
• 2011

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.

• 공업화학
• /
• 제19권2호
• /
• pp.179-184
• /
• 2008

숙신산은 식품, 의약, 화장품 등의 생산에서 중요한 화학물질로 부각되고 있으며, 향후 많은 분야에 사용될 가능성이 큰 원료물질이다. 일반적인 화학합성법과는 달리, 바이오매스와 환경 친화적 생물공정에 의해 생산되는 숙신산은 주로 염의 형태로 존재하므로 무기이온 제거를 위한 후속공정으로 전기투석공정이 반드시 필요하다. 전기투석 공정의 최적화를 위해 전압, 농도, pH 등의 인자 중에서 반응변수(response)인 탈염도 및 에너지 소비량에 영향을 주는 인자 선정 및 그 중요도 분석을 실험계획법을 이용하여 수행하였다. 2 수준 3인자 완전 요인 설계표에 의거하여 실험을 수행하였고, 실험결과의 미니탭 분석을 통해 전압이 가장 중요도가 큰 인자임을 알았다. 또한, 반응변수 최적화 도구를 이용하여 반응변수의 목표 값을 만족시키는 인자의 최적 조합을 찾고자 하였다. 한편, 전하를 띄지 않는 발효잔류물이 탈염에 미치는 영향을 조사하기 위해 농축 발효 옥수수 침출물, 이스트 추출액, 덱스트로즈 등의 함량에 따른 숙신산염의 탈염도 변화를 고찰하였다.