전산유체를 활용한 정수공정에서 전염소 공정 최적설계 방안

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.5

Pre-chlorination process is the first step in portable water process in order to oxidize such as algae, bacteria, organic matter, iron and manganese. In addition, It is may be used to prevent the growth of organisms within the water intake facilities and an water treatment facilities. Thus, depending on the purpose of pre-chlorination, chlorine injection point and how careful design is required. The pre-chlorine can be put at the intake conduit grit chamber, absorbing well of intake pumping station, intake pipe, receiving well. we evaluated most suitable design method of pre-chlorination process by using computational fluid dynamics. The study results, the injection way of chlorine at the intake conduit and pipe is efficient the direct pipe than perforated pipe. Also, mixing length of injected chlorine is four times of pipe diameter. The method of pre-chlorination injection in grits chamber is efficient the perforated pipe. Uniformity of effluent amount at the each hole is inversely proportional to the area ratio. Efficient injection way of chlorine within absorbing well of intake pumping station is the direct pipe than the perforated pipe. chlorine injection pipe should ensure a sufficient distance from the operating pump. The gap between the operating pump and the other is the shorter the better. The optimal depth of the injection pipe is between middle depth and inflow pipe of pump.

전산유체역학(CFD)를 활용한 정수공정에서 압력수 확산공정 진단

조영만(Young Man Cho),유수전(Soo Jeon Yoo),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin),최광주(Kwang Ju Choe),이광욱(Kwang Ug Lee),이기봉(Gi Bong Lee),이정규(Jeong Gyu Lee) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.5

압력수 확산공정은 정수공정에서 응집제나 염소용해수를 고압의 압력수로 분사하여 혼합하는 공정이다. 본 연구의 목적은 압력수 확산공정에 대한 전산유체역학적(Computational Fluid Dynamics) 진단을 통해 투입한 약품의 완전 혼합거리 및 혼합 거리를 줄이기 위한 확산판의 크기와 설치거리를 도출하는 것이다. 진단결과 2,200 mm 대형관에 5 kg/cm2 압력수를 50 mm, 100 mm 분사관으로 분사할 경우 혼합이 완료되는 혼합거리는 4D였다. 혼합거리를 줄이기 위해 분사관 전방에 확산판을 설치할 경우 분사관이 50 mm일 때 0.1D 직경의 확산판을 분사관 전방 0.2D 거리에 설치하면 혼합거리를 3D로 줄일 수 있다. 그러나 분사관이 100 mm인 경우는 확산판의 크기와 설치 거리와는 상관없이 확산판이 없는 4D보다 확산거리를 줄일 수 없는 것으로 진단되었다. 따라서 2,200 mm 관에 압력수를 분사하는 경우는 50 mm 분사관을 설치하는 것이 100 mm보다 휠씬 효율적인 것으로 나타났다. The Process of Pressurized water diffusion is mixing process by pressurized water injection with coagulate and chlorine water in the water treatment system. The objectives of this research were to evaluate the mixing length and diameter of diffusion plate and distance from injection pipe for complete mixing by using computational fluid dynamics. From the results of CFD simulation, when diameter of injection pipe is 50 mm, 100 mm and injection pressure is 5 kg/cm2 and the diameter of inlet pipe is 2,200 mm, the complete mixing length is 4D (D: Length as diameter of inlet pipe). When diameter of injection pipe is 50 mm, the diameter of the diffusion plate in o.1D and distance from injection pipe is 0.2D, the complete mixing length is 3D that is the most short mixing length. But when diameter of injection pipe is 100 mm and mutually related the diameter, distance of diffusion plate, the complete mixing length is 4D over. Therefore, as the diameter of inlet pipe is 2,200 mm, the injection pipe 50 mm is more efficient than 100 mm.

전산유체역학을 활용한 유공관 최적설계 및 맥동식침전지 수리평가

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.4

The pulsator clarifiers is very sensitive about the changing of the water quantity. So the most important part of pulsator clarifiers is the perforated pipe for to drain the raw water with equal pressure and velocity. First, we evaluated the design parameters of the common perforated pipe. The uniformity of outflow from the perforated pipe is directly affected according to area ratio. In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter(2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. Second, we evaluated the pulsator clarifiers that has installed and operated in H water treatment plant. Results, it was designed properly that the ratio of cross section between pipe and holes is 8.9%. But the distance of each holes should be improved to 2/D of the optimal value from 1.3/D. The standard deviation of distributed quantity from the middle channel to the hole pipe was 0.12 and from the hole pipe to holes was 0.04.

수처리 공정에서 디지털트윈 요소기술과 추진방안

조영만 ( Cho Young-man ),정용준 ( Jung Yong-jun ) 한국물환경학회 2022 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2022 No.-

이동식 정류장치를 이용한 횡류식 침전지 침전효율 개선 연구

조영만(Young Man Cho) 大韓環境工學會 2005 대한환경공학회지 Vol.27 No.7

전산유체역학을 활용한 응집지 분배수로 최적설계

조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.4

Uniform distribution at the channel and pipe is an important factor affecting not only floc formation of flocculation basin but also precipitation efficiency of sedimentation basin. There are a variety of design factors at the distribution channel such as the open channel type, pressure pipe type, velocity of channel inside, structure of inlet, outlet size, etc. we evaluated most suitable design method of the distribution channel of the flocculation basin by using computational fluid dynamics in this research. First, the uniformity of distribution is improved when the ratio of channel inlet and outlet Cross-sectional area small. If, however, the ratio of Cross-sectional area is become small, pressure in the channel rises. So the basis of the uniformity and pressure in channel, the suitable ratio of Cross-sectional area is about 5%~10%. Second, in the uniformity of distribution, the pressure pipe type is excellent than the open channel type. Third, the suitable inlet velocity of water is about o.5m/sec if consider the prevent sedimentation of SS and the rise of pipe pressure. Fourth, we can improve the stability of water flow by increasing the length of the inlet section, therefore proper inlet length is about 5m.

CFD를 활용한 수처리공정 대형관에서 압력수 혼합공정 평가

조영만 ( Young-man Cho ),유현철 ( Hyun-chul Yu ),장경혁 ( Gyeong-hyuk Jang ),정용준 ( Yong-jun Jung ) 한국물환경학회(구 한국수질보전학회) 2021 한국물환경학회지 Vol.37 No.3

Mixing is a very important unit in water treatment process. A mechanical stirring method is generally used for mixing, but recently, the use of pressurized water mixing method (pump diffusion flash mixer) has gained interest because it is more advantageous in terms of mixing time, noise, energy consumption, and maintenance. The following conclusions were obtained from the study of pressurized water mixing method by Computational Fluid Dynamics. Firstly, the mixing degree in the pipe increased as the density of water increased. Secondly, even if the relative velocity between flow rate in the pipe and the pressurized water was constant, the mixing degree decreased as the flow velocity in the pipe increased. Thirdly, the stronger the injection energy the higher the mixing degree. It was also found that the mixing degree was greatly affected by the injection velocity as compared to the injection flow amount. Finally, the required energy to achieve 95% mixing degree at the distance of 10 times diameter in big pipes of 500 mm to 3000 mm was 0.3 to 4.5 kJ. The result of this study could be used in the process design of injection with water purification chemicals, such as, ozone, chlorine, and coagulant.

전산유체를 활용한 정수지 최적 도류벽 형태 및 경제적인 장폭비 산정

조영만(Young Man Cho),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin),김태균(Tae Kyun Kim),최영준(Young June Choi) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.6

현재 국내 정수지 도류벽은 형태와 장폭비에 대한 명확한 기준이 없고 장폭비가 너무 작아 소독능을 만족하지 못하거나 지나치게 큰 장폭비로 비경제적인 설계를 하는 등 많은 혼란을 겪고 있어 수리적으로 유리한 도류벽의 형태와 경제적인 장폭비를 결정하는 것이 시급한 실정이다. 본 연구는 다양한 도류벽의 형태와 장폭비에 대해 전산유체역학 기법을 활용하여 수리적으로 가장 유리한 도류벽의 형태를 제시하고 가장 경제적인 장폭비를 도출하였다. 연구결과, 정수지내 도류벽의 형태는 동일한 형태와 구조라 하더라도 수류의 방향전환 횟수가 적은 구조가 수리적으로 유리하다. 둘째, 최적 도류벽 형태는 좌우 우류식(model 2)이며 최악의 형태는 두 방향으로 분산되고 다시 모아지는 분산형(model 4) 형태이다. 좌우 우류식은 분산형보다 도류벽의 개수를 67% 정도 줄일 수 있다. 셋째, 좌우 우류식 도류벽인 경우 경제적인 장폭비는 30~50이며 50을 초과할 경우 공사비 대비 T10/T 값의 증가량이 미미하여 경제적이지 못하다. We need to make the standard of the best baffle shape and L/W ratio of clearwell due to insufficient disinfection in short L/W ratio and uneconomic design in long L/W ratio. The objectives of this research were to evaluate the best shape of baffle and economic L/W ratio in the all sorts of shape and size by using computational fluid dynamics. In the results of this research, the baffle with smaller number of turning flow is more beneficial for hydraulic efficiency. So, even if the same shape and structure, baffle should be designed as smaller number in turning flow. The best shape of baffle is ZigZag type (model 2) and the worst shape is Distributed types (model 4). The ZigZag type can reduce number of baffle about 67% than that of the Distributed types. In the ZigZag type, economic L/W ratio is 30~50. If L/W ratio exceed over 50, it is not economic because construction costs greatly increase and an increasing rate of T10/T is very small.

전산유체역학(CFD)를 활용한 정수공정에서 유공관 설계

조영만(Young Man Cho),유수전(Soo Jeon Yoo),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.9

정수공정에서 활용되고 있는 유공관의 일반적인 기능은 균등한 압력으로 일정한 유량을 유출시키는 것이다. 정수공정에서 유공관이 여러 공정에서 활용되고 있음에도 불구하고 유공관 설계에 대한 일반적인 설계인자가 없는 실정이며 따라서 본 연구에서는 전산유체역학적(Computational Fluid Dynamics) 기법을 활용하여 정수공정에 활용되고 있는 유공관 설계인자를 도출하고자 하였다. 유공관 유출량의 균등성은 유공관 표면적 대비 전체 유공단면적 합의 비가 작아질수록 향상되는 경향을 보인다. 즉 유공 면적비가 작아질수록 유출 균등성은 그에 비례하여 향상되며 또한 동일한 면적비에서 유공의 개수가 증가할수록 유출량 균등성은 향상된다. 특히 유공관의 직경에 해당하는 길이 당 2개의 유공(2/D)을 배치하는 경우가 균등성의 향상 폭이 가장 크며 또한 압력 강하 값이 가장 적어 수리학적으로 가장 유리한 유공 개수이다. 유공관 유입 유속이 작고(약 0.06 m/s), 유공관 길이가 길어질수록 유출량은 전단에서 후단으로 갈수록 감소하며 반대로 유공관 유입 유속이 크고 (3 m/s) 유공관이 길어지면 유출량은 후단으로 갈수록 증가하는 경향을 보인다. Role of the perforated pipe is to drain the water with equal pressure and velocity through the holes of perforated pipe. The perforated pipe is being used in many processes of water treatment system, however, the design parameter of perforated pipe is not standardized in korea. In this study, we have found the design parameter of perforated pipe in the water treatment system using the Computational Fluid Dynamics (CFD). The uniformity of outflow from the perforated pipe is directly affected according to area ratio (gross area of holes/surface area of the perforated pipe). In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter (2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. When the inlet velocity of pipe is about 0.06m/sec, the flux of pipe has decreased as from front to backward. When the inlet velocity is 3 m/s, the flux of pipe has increased as from front to backward.

부산시 감조하천 동천의 수리 특성

조영만 ( Young Man Cho ),류동춘 ( Dong Choon Ryu ),유평종 ( Pyeong Jong Yoo ),최민식 ( Min Sik Choi ),설승수 ( Seung Su Seol ),김상현 ( Sang Hyun Kim ),이종진 ( Jong Jin Lee ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.2

Even though various management practices such as sediment dredging were attempted to improve water quality of Dongcheon located in Busan, the environmental condition of this stream was deteriorated. Therefore, Busan metropolitan city had pumped and diverted sea water to upstream of Dongcheon for several years. This study explored hydraulic characteristics of Dongcheon to configure the best management practice for ecological restoration and water quality improvement of a man made urban stream. Intensive field investigation indicates that average flow velocities at depths of 20% and 80% from the water surface ranged 5 to 10 cm/s and 2 to 5 cm/s, respectively. Concentrations of dissolved oxygen for all depths were less than 0.25 mg/l during low tidal period. Even though density difference can be found along stream depth, density current seems rarely generated in Dongcheon. Short period of high tidal portion and shallow depths are responsible for well mixing nature of Doncheon.