Real-time Control Parameters Research Articles

Real-time Engine Control Parameters Optimization Method for Small Diesel Engine by Multi Objective Genetic Algorithm

Real-time Engine Control Parameters Optimization Method for Small Diesel Engine by Multi Objective Genetic Algorithm

가축분뇨처리공정의 자동제어 인자 신뢰성 평가 및 적정 외부탄소원 공급량 지표 확립

다양한 조건하에서 가축분뇨처리공정을 운전하면서 각 자동제어 인자의 반응을 분석하고 ORP, DO, pH(mV)-time profile를 이용한 자동제어 신뢰성을 평가하였다. 또한 무산소 조건에서의 잔존 유기물 및 미생물 자기산화에 의한 탈질율을 고려한 적정 외부탄소원 공급량 지표를 파악하였다. 실험은 45L의 유효용적을 지닌 실험실 규모의 SBR 공정을 이용하여 수행되었다. ORP-와 pH(mV)-, DO-time profile 상에서 완전질산화를 의미하는 NBP가 뚜렷하게 발현하던 중 NH4-N의 낮은 부하와 고농도 NOx-N 함유 폐수의 유입 및 불충분한 무산소 조건 제공이 이루어졌을 때 ORP-와 DO-time profile 상에서 NBP가 사라지기 시작하였으며 NOx-N의 지속적인 증가에 의해 ORP 값의 민감성이 둔화되기 시작하였다. 그러나 pH(mV)-time profile은 항상 일정한 변화패턴을 유지하면서 암모니아성 질소의 완전 질산화가 이루어졌을 때 뚜렷한 NBP를 발현하였다. NOx-N/NH4-N의 비가 80:1 수준까지 높아지는 조건하에서도 pH(mV)- time profile상에서의 이러한 안정적 NBP의 발현은 지속되었으며 발현되는 NBP는 MSC(Moving Slope Change)의 변화 패턴을 추적함에 의해 인식되도록 프로그램 할 수 있었다. pH(mV)-time profile에서의 NBP의 발현과 MSC를 이용한 자동제어시점 인식은 반응조내 NOx-N 농도가 무려 300mg/L 이상의 수준에서도 안정적이었다. 유기물 농도에 따른 자동제어 인자의 반응을 분석한 시험에서도 반응조내 유기물의 농도가 STOC 기준 약 10,000mg/L 수준으로 증가함에도 불구하고 pH(mV)-time profile 상에서의 이러한 NBP 발현은 지속되었으며 고농도 유기물 축적 하에서도 동일한 자동제어 알고리즘이 이용될 수 있음을 알 수 있었다. 잔존 유기물과 미생물 자기산화에 의한 탈질율은 약 0.4mg/L.hr로 분석되었으며 안전지수 0.1을 도입하여 산출된 NOx-N 기준 적정 외부탄소원 공급량은 0.83 STOC/NOx-N으로 파악되었다. Responses of real-time control parameters, such as ORP, DO and pH, to the conditions of biological animal wastewater treatment process were examined to evaluate the stability of real-time control using each parameter. Also an optimum index for supplemental carbon source addition based on NOx-N level was determined under a consideration of denitrification rate by endogenous respiration of microorganism and residual organic matter in liquor. Experiment was performed with lab-scale sequencing batch reactor(SBR) and working volume of the process was 45L. The distinctive nitrogen break point(NBP) on ORP-and DO-time profiles, which mean the termination of nitrification, started disappearing with the maintenance of low NH4-N loading rate. Also the NBP on ORP-and DO-time profiles was no longer observed when high NOx-N was loaded into the reactor, and the sensitivity of ORP became dull with the increase of NOx-N level. However, the distinctive NBP was constantly occurred on pH(mV)-time profile, maintaining unique profile patterns. This stable occurrence of NBP on pH(mV)-time profile was lasted even at very high NOx-N:NH4-N ratio(over 80:1) in reactor, and the specific point could be easily detected by tracking moving slope change(MSC) of the curve. Revelation of NBP on pH(mV)-time profile and recognition of the realtime control point using MSC were stable at a condition of over 300mg/L NOx-N level in reactor. The occurrence of distinctive NBP was persistent on pH(mV)-time profile even at a level of 10,000mg/L STOC(soluble total organic carbon) and the recognition of NBP was feasible by tracing MSC, but that point on ORP and DO-time profiles began to disappear with the increase of STOC level in reactor. The denitrfication rate by endogenous respiration and residual organic matter was about 0.4mg/L.hr., and it was found that 0.83 would be accepted as an index for supplemental carbon source addition when 0.1 of safety factor was applied.

Optimal gear ratios of drives

One of the most complex problems in the design of practically any mechanism or machine is to select the gear ratio of an electric drive, on the basis of scientific, engineering, and economic principles. There is an extensive literature on this subject, dating mainly to the period from the 1940s to the 1960s. In current economic conditions, however, this problem is important, first, in connection with the need to find hidden reserves in existing technological equipment and, second, on account of the computerization of design systems (the availability of CAD systems) and the wide introduction of high-speed microprocessor control systems, which considerably increase production efficiency. In my view, information technologies and microprocessor control systems for electric drives, with elements of artificial intelligence and self-diagnostics, may soon permit the replacement (at least partial) of large, metalheavy, labor-intensive mechanical transmissions and gear systems. For example, the creation of microprocessor-based speed-adjustment systems and power (torque) converters seems possible even today. In addition, in real-time microprocessor control, the speed and dynamic parameters of the drive may be varied within certain limits, so as to operate as closely as possible to the optimal gear ratio or transfer function (the gear ratio as a function of the angle of rotation for lever systems). As a result, hidden reserves of the equipment may be implemented, with a perceptible economic benefit. In most research devoted to selecting the optimal gear ratio of a drive, the optimum is assumed to correspond to maximum speed of the executive mechanism or to minimum heat losses in the armature circuit of the independent-excitation dc motor, when the necessary displacement and processing time are specified. In the present work, we consider the search for the optimal gear ratio using Pontryagin’s maximum principle (from the mathematical theory of optimal processes) for both of these criteria and also for the case of minimum heat losses in the motor’s armature circuit [1]. The results obtained may be regarded to some extent as a generalization of existing research on optimal gear ratios.

The effects of preozonation on the biodegradability of mixed phenolic solution using a new gas-inducing reactor

In this study, the effects of preozonation on the biodegradability of mixed 2-chlorophenol/4-cresol solution were investigated using a new gas-inducing reactor, which can provide high ozone utilization efficiency. The decomposition rate of phenolic mixture, COD removal and TOC removal increases with increasing pH. A half-order overall kinetic model can correctly describe the decomposition of phenolic mixture. The BOD 5/COD ratio of the preozonized solutions increases with increasing preozonation time, indicating that preozonation can enhance the biodegradability. Based on high ozone utilization rate, it is concluded that the best characteristic time can be chosen at the rapid increase of ozone gas outlet concentration. Since the ozone gas outlet concentration can be easily monitored, it is a useful real-time control parameter in preozonation.

생물학적 축산폐수 처리공정의 자동제어 방법 및 제어 인자의 안정성

SBR 처리공정의 자동제어 인자로서의 ORP, pH, DO의 안정성과 유용성을 비교 평가하였다. 시스템 운전동안 ORP와 pH(mV)-time profile 상에서 요염물질의 특이적인 변화시점을 나타내는 NBP와 NKP가 잘 나타났으며 이 시점은 MSC(moving slope change)를 이용하여 쉽게 인식될 수 있는 것으로 밝혀졌다. 그러나 부하량과 포기량 혹은 시스템 OUR이 불균형일 때는 DO나 ORP-time profile 상에서 NBP로 잘못 인식될 수 있는 가짜 제어시점이 여러 번 발생하거나 혹은 제어시점으로 인식할만한 변화가 전혀 발생하지 않음을 알 수 있었다. 그러나 pH(mV)-time profile에서는 어떤 운전조건과 상태에서도 항상 뚜렷한 NBP가 발생하고 MSC를 이용한 제어시점 인식이 가능함을 알 수 있었다. 따라서 호기적 처리과정 중의 시스템 진단과 자동제어 인자로 ORP나 DO 보다 pH(mV)가 안정적임을 알 수 있었다. 반면 무산소 상태의 모니터나 제어에 있어서는 pH(mV)-time profile에서 NKP를 안정적으로 인식하는 데에는 한계가 있었으나 ORP에서는 매우 안정적인 것으로 나타나 무산소 처리과정의 진단/제어인자로는 ORP가 다른 인자들 보다 유용함을 알 수 있었다. 이러한 결과로 미뤄 SBR 공정의 안정적인 자동제어를 위해서는 ORP 혹은 pH(mV)를 단독으로 이용하는 것 보다는 병용하는 것이 바람직하며, 이러한 자동제어기술은 유입수내 오염물질의 농도 변이와 운전여건에 상관없이 항상 오염물질의 완전제거를 가능케 함은 물론 처리시간 및 처리용량의 최적화를 위한 실용적 기술이 될 것으로 판단된다. The feasibility and stability of ORP, pH(mV) and DO as a real-time control parameter for SBR process were evaluated in this study. During operation, NBP(nitrogen break point) and NKP(nitrate knee point), which reveal the biological and chemical changes of pollutants, were clearly observed on ORP and pH(mV)-time profiles, and those control points were easily detected by tracking the moving slope changes(MSC). However, when balance of aeration rate to loading rate, or to OUR(oxygen uptake rate), was not optimally maintained, either false NBP was occurred on ORP and DO curves before the appearance of real NBP or specific NBP feature was disappeared on ORP curve. Under that condition, however, very distinct NBP was found on pH(mV)-time profile, and stable detection of that point was feasible by tracking MSC. These results might mean that pH(mV) is superior real-time control parameter for aerobic process than ORP and DO. Meanwhile, as a real-time control parameter for anoxic process, ORP was very stable and more useful parameter than others. Based on these results, a stable real-time control of process can be achieved by using the ORP and pH(mv) parameters in combination rather than using separately. A complete removal of pollutants could be always ensured with this real-time control technology, despite the variations of wastewater and operation condition, as well as an optimization of treatment time and capacity could be feasible.

The Preozonation of Phenolic Aqueous Solution and Its Effect on the Improvement of Coagulation Treatment

Phenolic solutions are difficult to treat with coagulation processes because phenol is well soluble in water. However, with suitable preozonation, the ozonized organic components can be removed more effectively by coagulation processes. In order to avoid excessive preozonation, a good control on the degree of preozonation is crucial for practical applications. The degree of preozonation of phenolic solution was evaluated by measuring the phenol decomposition rate, ADMI value and ozone outlet concentration during the ozonation. Three characteristic times were observed, namely (1) ADMI value reaches the peak value during preozonation, (2) the ozone outlet concentration starts increasing, and (3) the ADMI value reaches the discharge standard (500 value, EPA Taiwan). These characteristic times provide the useful means as real-time control parameters on the extent of preozonation. The results of HPLC and GPC show that phenol is almost completely decomposed after 43 min of preozonation. The major components after preozonation are oxalic acid and coupling compounds. The preozonized solution, containing phenol decomposition products, was then subjected to coagulation treatments. The coagulation behavior of preozonized solution is dependent on the extent of preozonation. Three types of coagulant were investigated, namely alum, ferric chloride (FeCl3) and poly aluminum chloride (PAC). Both PAC and FeCl3 are effective coagulants for COD removal. As an example, phenol solution (initial phenol concentration=300 mg/L, C O 3,i=20 mg/L) was preozonized for 50 minutes, followed by FeCl3 coagulation treatment. After preozonation and coagulation processes, the total COD and ADMI removal rates are as high as 70% and 80%, respectively. Most of the coupling compounds and oxalic acid are removed by the coagulant.

Biological nitrogen removal with enhanced phosphate uptake in a sequencing batch reactor using single sludge system

Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake was investigated in an anaerobic–aerobic–anoxic–aerobic sequencing batch reactor ((AO) 2 SBR). Significant amounts of phosphorus-accumulation organisms (PAOs) capable of denitrification could be accumulated in a single sludge system coexisting with nitrifiers. The ratio of the anoxic phosphate uptake to the aerobic phosphate uptake capacity was increased from 11% to 64% by introducing an anoxic phase in an anaerobic–aerobic SBR. The (AO) 2 SBR system showed stable phosphorus and nitrogen removal performance. Average removal efficiencies of TOC, total nitrogen, and phosphorus were 92%, 88%, and 100%, respectively. It was found that nitrite (up to 10 mg NO 2 −–N/l) was not detrimental to the anoxic phosphate uptake and could serve as an electron acceptor like nitrate. In fact, the phosphate uptake rate was even faster in the presence of nitrite as an electron acceptor compared to the presence of nitrate. It was found that on-line sensor values of pH, ORP, and DO were somehow related with the dynamic behaviours of nutrient concentrations (NH 4 +, NO 3 −, and PO 4 3−) in the SBR. These on-line sensor values were used as real-time control parameters to adjust the duration of each operational phase in the (AO) 2 SBR. The real-time controlled SBR exhibited better performance in the removal of phosphorus and nitrogen than the SBR with fixed-time operation.

Identifying useful real-time control parameters in ozonation process

Industrial wastewaters that contain phenolic compounds are resistant to biodegradation and need preoxidation to improve their biodegradabilities. Preoxidation of these wastewaters by using ozone as the chemical oxidant has been found previously to be quite effective in promoting their biodegradability. In combined ozonation and biological processes, if we want to stop ozonation at the optimum condition (i.e. the maximum biodegradability), a biodegradation test is required. Since biodegradation tests such as BOD/TOC and oxygen uptake would take a long time, we could not know the time to stop ozonation immediately. This study was undertaken to identify process parameters (pH, ORP, ozone concentration in water, ozone gas concentration at the reactor outlet) that could be useful for monitoring and real-time control purposes in ozonation processes. We want to correlate these parameters with biodegradability and intermediates formed in ozonation processes. Results showed that the rapid increase of dissolved ozone and the first plateau termination of off-gas ozone concentrations are good indicators for the depletion of p-nitrophenol, the maximum of biodegradability and the elimination of toxicity. From the mean oxidation state curve, ozonation of p-nitrophenol could be divided into three stages, and a similar pattern could also be observed in ORP profiles. From the results of this research, the application of ozone concentration and ORP profiles as real-time control parameters seems promising.

Controlling factors for simultaneous nitrification and denitrification in a two-stage intermittent aeration process treating domestic sewage

This bench-scale research investigated the controlling factors for simultaneous nitrification and denitrification (SND) in a 2-stage, intermittent aeration (IA) process, designed for nitrogen and phosphorus removal. The 2-stage process consisted of an anaerobic zone followed by an oxidation–reduction potential (ORP) controlled, intermittently aerated, completely mixed (IACM), tank. The three independent variables examined were the average ORP level, organic substrate (acetate and methanol) dosage and aeration cycle. The sewage used was completely of residential origin. Nitrogen balance clearly indicated that the nitrogen loss, due to SND in the aeration tank, contributed 10% to 50% of the influent TKN to the overall nitrogen removal. Significant differences in both nitrification and denitrification in the IACM tank were observed, when different average ORP levels were applied to the aeration control; this proved that absolute ORP can be used as a real-time control parameter for SND. Under low DO and intermittent aeration conditions, acetate and methanol additions improved nitrification over the entire dosage range and denitrification at relatively low dosages. Finally, a longer aeration cycle, with a zero-DO period, appeared to favor sequential nitrification and denitrification (SQND), not SND.

Real-Time Control of Two-Stage Sequencing Batch Reactor System for the Treatment of Animal Wastewater

An evaluation of the use of ORP as a real-time control parameter was conducted. A newly developed real-time control strategy, using ORP, was successfully applied, without a supplemental carbon source, to a new type of bench-scale two-stage SBR process for the treatment of swine wastewater. With real-time control, consistently high system performances were obtained, despite the fluctuation of influent quality; removal efficiencies for BOD5, COD, NH4-N, TKN, Ortho-P, Total Phosphorus (TP) averaged approximately 99.6%, 97%, 98%, 96%, 95% and 94%, respectively. Also, effective denitrification could be achieved without the addition of an external carbon source; the average NOx-N level on final effluent was 11 mg l−1. The data from this study reveal that both the ORP and pH can be used as successful process control parameters in the optimization of nutrient removal and treatment system capacity. Feasible real-time control strategies using dynamic ORP and pH change are established through this research.

Sequencing Batch Reactor System for Nutrient Removal: ORP and pH Profiles

The sequencing batch reactor (SBR) process is known for its flexibility to meet a wide range of treatment needs, including nutrient removal. However, information related to the operational stability of SBR nutrient removal systems and control parameters to adjust the cyclic duration is sparse. Consequently, this study was undertaken to identify process parameters (pH and oxidation reduction potential) that could be useful for monitoring and real-time control purposes. In general, the system achieved removal efficiencies of 91, 98 and 98%, respectively, for Chemical Oxygen Demand, total nitrogen and phosphate at the solids retention time of 10 days, with a cyclic duration of 6 h. Shock loadings of nitrogen (20 mg dm -3 of NH 4 + -N, four cycles) exhibited little impact on effluent quality, except for a higher nitrate content. Activated sludge settled well throughout the entire study period. Several significant points associated with different reactions within SBR cycle, e.g. end of nitrification, end of phosphate release and completion of phosphate uptake, were identified in pH profiles. Slope changes in pH profiles (dpH/dt, or d 2 pH/dt 2 ) were found to better represent the corresponding biological reactions. The application of these significant points in pH profiles as real time control parameters appears promising.

USING pH AS A REAL-TIME CONTROL PARAMETER FOR WASTEWATER TREATMENT AND SLUDGE DIGESTION PROCESSES

The alternating aerobic-anoxic (AAA) process offers many advantages for wastewater treatment and sludge digestion. Laboratory scale experiments were conducted to investigate the feasibility of using pH as a realtime control parameter for this process. Several well defined control points on the pH curve were identified, e.g., ammonia valley and nitrate apex. These points were directly related to the alternating nitrification and denitrification reactions in the process, and were found to be consistent with those previously identified using ORP. Although both pH and ORP can be used as real-time control parameters, pH provides several additional advantages over ORP. Based on these findings, real-time control strategies (fixed pH setpoints and dynamic pH control) were developed and tested. Results from laboratory scale AAA sludge digestion using fixed pH setpoints (6-8) indicated that 36% MLVSS reduction, 39% TN reduction and almost 48% saving in aeration energy was achieved after 300 hrs of digestion.