Long-term operation optimization of circulating cooling water systems under fouling conditions

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.

Biodegradation Behavior of Starch in Simulated White Water System of Old Corrugated Cardboard Pulping Process

Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized,thereby resulting in severe resource wastage and environmental pollution.This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates(native starch and enzymatically(α-amylase)hydrolyzed starch),which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC)technologies.The effects of system temperature,pH value,starch concentration,and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied.In addition,the effect ofα-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated.It was found that the native starch presented a maximal degradation ratio at a system temperature of 55℃and pH value range of 5-7,respectively,the corresponding starch concentration within simulated white water system was 200 mg/L.Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50℃and pH value of 5.5,respectively,and the corresponding starch concentration within simulated white water system was 100 mg/L.It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process,while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch.This study provides a practical and interesting approach to investigate the starch hydrolysis or biodegradation behaviors in white water system of OCC pulping process,which would greatly contribute to the full recycling and valorized application of starch as a versatile additive during paperboard production.

An Evaluation of Phase Behaviors of the Oil-Gas-Water System in the Displacement of Crude Oil with CO_(2)

CO_(2)dissolution into an aqueous phase and water evaporation into a gaseous phase takes place during CO_(2)injection into an oil reservoir.This study aims to evaluate the phase behaviors of the oil-gas-water system in the displacement of crude oil by CO_(2).The composition of the JL oilfield in the northeast of China is taken as an example.The flash calculation of the oil-gas-water system was performed,based on the method presented by Li and Nghiem.The research results show that CO_(2)dissolution in the aqueous phase declines as the NaCl concentration in formation water rises.CO_(2)injection is beneficial for the evaporation of formation water.The NaCl concentration in formation water has little effect on water evaporation and dissolved-gas escape.When the injection-gas mole fraction of CO_(2)is 0.5,CO_(2)injection can reverse the phase behavior of the petroleum mixture and the oil-gas system is converted to a pure gas-condensate system.For CO_(2)injection,water vapor has little effect on the miscibility of multiple contacts,but can reduce the miscibility of the first contact.

Water System Condition and Asset Replacement Prioritization

The goal of asset management is to identify and track the maintenance and replacement of assets that have reached their useful life. For that reason, gathering data and collecting information is a critical step when developing an asset management plan. Such data gathering includes physical and operational properties of the assets as well as collecting and tracking important events during the lifespan of the asset (i.e., pipe breaks, replacement year, maintenance performed, etc.). Critical factors in the asset management plan may be overlooked when there is no data or poor quality data. However, many utilities lack the resources for examining buried infrastructure and lack good quality work order data, so other methods of data collection are needed. The concept for this paper was to develop a means to acquire data on the assets for a condition assessment to identify pipes that were most likely to break and those with the highest consequences for same. Three utilities were used as examples. It was found that for buried infrastructure, much more information was known than anticipated but the actual predictions relied on only a few factors related to pipe type. However, there is a need to track the consequences, in this case breaks, which would indicate a failure. The latter would be useful for predicting future maintenance needs and the most at-risk assets, but is often missing in utility systems as many utilities do not adequately track breaks sufficiently. In this case two utilities were analyzed and predication on a third was developed.

Morphological Difference and Karyotype of Pelteobagrus fulvidraco in Dongting Lake Water System

[Objective] The research aimed to study the morphological characteristics and karyotype of Pelteobagrus fulvidraco in Dongting Lake water system.[Method] By using the conventional biological morphometry,PHA and colchicine injection method in vivo,the morphological characteristics and karyotype of P.fulvidraco in Yuanshui River and Lishui River of Dongting Lake were analyzed.[Result] In three ratio traits including standard length/head length,standard length/caudal peduncle depth,head length/snout length,P.fulvidraco of Yuanshui River and Lishui River had significant differences（P0.05）.However,the number and karyotype of their chromosomes were same.The chromosome number was 2n = 52,and the karyotype formula was 20M＋12SM＋10ST＋10T.The number of chromosome arm was 84.[Conclusion] The research result had certain theoretical guidance significance for the protection and utilization of wild P.resource in Dongting Lake water system.

MODELING STUDY ON REMOVAL OF NITRATE IN WATER SYSTEM BY BACTERIA TRANSPLANTED IN UNSATURATED ZONE

With a view to treating the nitrate pollution in water systems,this article presents a novel method for eliminating nitrate from wastewater by bacteria through unsaturated zone. First,highly efficient denitrifiers suitable for underground environment have been studied based on the biochemical characterization and denitrifying mechanism of microorganisms. Then the nitrate-eliminating modeling study in soil columns was carried out with the obtained denitrifier. The results show that the nitrate-eeliminating efficiency can reach 98%,so it has practical value in controlling nitrate pollution in water systems.

Analysis on the Interaction of Parameters of Single-contaminant Regeneration Recycling Water Systems

Method for constructing the optimal water supply line and formulas for calculating the targets for single-contaminant regeneration recycling water systems are improved to apply to the situation of variational pararneters in this article. Based on these extending methods, the effect of varying freshwater consumption and regenerated water flow rate on the optimizing results are investigated. The interactions of parameters of regeneration recycling systems are summarized. Finally, all the conclusions are illustrated from the results of mathematical programming through an example.

Flexibility Prediction of Aggregated Electric Vehicles and Domestic Hot Water Systems in Smart Grids

With the growth of intermittent renewable energy generation in power grids,there is an increasing demand for controllable resources to be deployed to guarantee power quality and frequency stability.The flexibility of demand response(DR)resources has become a valuable solution to this problem.However,existing research indicates that problems on flexibility prediction of DR resources have not been investigated.This study applied the temporal convolution network(TCN)-combined transformer,a deep learning technique to predict the aggregated flexibility of two types of DR resources,that is,electric vehicles(EVs)and domestic hot water system(DHWS).The prediction uses historical power consumption data of these DR resources and DR signals(DSs)to facilitate prediction.The prediction can generate the size and maintenance time of the aggregated flexibility.The accuracy of the flexibility prediction results was verified through simulations of case studies.The simulation results show that under different maintenance times,the size of the flexibility changed.The proposed DR resource flexibility prediction method demonstrates its application in unlocking the demand-side flexibility to provide a reserve to grids.

Optimization of circulating cooling water systems based on chance constrained programming

Recent research on deterministic methods for circulating cooling water systems optimization has been well developed. However, the actual operating conditions of the system are mostly variable, so the system obtained under deterministic conditions may not be stable and economical. This paper studies the optimization of circulating cooling water systems under uncertain circumstance. To improve the reliability of the system and reduce the water and energy consumption, the influence of different uncertain parameters is taken into consideration. The chance constrained programming method is used to build a model under uncertain conditions, where the confidence level indicates the degree of constraint violation. Probability distribution functions are used to describe the form of uncertain parameters. The objective is to minimize the total cost and obtain the optimal cooling network configuration simultaneously.An algorithm based on Monte Carlo method is proposed, and GAMS software is used to solve the mixed integer nonlinear programming model. A case is optimized to verify the validity of the model. Compared with the deterministic optimization method, the results show that when considering the different types of uncertain parameters, a system with better economy and reliability can be obtained(total cost can be reduced at least 2%).

Analysis of Gardening Based on the Unique Zonal Water System of Slender West Lake

Yangzhou Slender West Lake is narrow in shape. It is 4.3 km in total length with the width of about 100 m. It is a typical zonal water system. Through the research of its spatial structure, space sequence and view borrowing the garden bridges of Yangzhou Slender West Lake, the unique gardening method of zonal water system was expatiated.

Prevalence of Opportunistic Pathogens and Diversity of Microbial Communities in the Water System of a Pulmonary Hospital

Objective Our objective was to investigate the occurrence of opportunistic pathogens and characterize the bacterial community structures in the water system of a pulmonary hospital.Methods The water samples were collected from automatic and manual faucets in the consulting room,treatment room,dressing room,respiratory ward,and other non-medical rooms in three buildings of the hospital.Quantitative polymerase chain reaction was used to quantify the load of several waterborne opportunistic pathogens and related microorganisms,including Legionella spp.,Mycobacterium spp.,and M.avium.Illumina sequencing targeting 16 S r RNA genes was performed to profile bacterial communities.Results The occurrence rates of Legionella spp.,Mycobacterium spp.,and M.avium were 100%,100%,and 76%,respectively in all samples.Higher occurrence rates of M.avium were observed in the outpatient service building(building 1,91.7%)and respiration department and wards(building 2,80%)than in the office building(building 3),where no M.avium was found.M.avium were more abundant in automatic faucets(average 2.21×10~4 gene copies/L)than in manual faucets(average 1.03×10~4 gene copies/m L)(P<0.01).Proteobacteria,Actinobacteria,Bacteroidetes,Cyanobacteria,Firmicutes,and Acidobacteria were the dominant bacterial phyla.Disinfectant residuals,nitrate,and temperature were found to be the key environmental factors driving microbial community structure shifts in water systems.Conclusion This study revealed a high level of colonization of water faucets by opportunistic pathogens and provided insight into the characteristics of microbial communities in a hospital water system and approaches to reduce risks of microbial contamination.

SELF-SIMILAR SOLUTIONS AND BLOW-UP PHENOMENA FOR A TWO-COMPONENT SHALLOW WATER SYSTEM

In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation.

Optimum Scheduling for the Chilled Water System of an Intelligent Building

The energy saving issue of chilled water system in an intelligent building is analyzed from the systematic point of view, and an optimum scheduling scheme which can save energy of the system facilities and satisfy the constraints of the real time cold loads and system running is also proposed. It can make the minimum cost of the system by optimizing the number of running chillers, running parameters and the distribution of real time loads of running chillers. The improved genetic algorithm is used in the optimum scheduling scheme. The computation results show that the building energy consumption can be decreased by about 10%.

Energy-Efficient Operation of Water Systems through Optimization of Load Power Reduction in Electricity Markets

Demand response(DR) is gaining more and more importance in the architecture of power systems in a context of flexible loads and high share of intermittent generation. Changes in electricity markets regulation in several countries have recently enabled an effective integration of DR mechanisms in power systems. Through its flexible components(pumps, tanks), drinking water systems are suitable candidates for energy-efficient DR mechanisms. However, these systems are often managed independently of power system operation for both economic and operational reasons. Indeed, a sufficient level of economic viability and water demands risk management are necessary for water utilities to integrate their flexibilities to power system operation. In this paper,we proposed a mathematical model for optimizing pump schedules in water systems while trading DR blocs in a spot power market during peak times. Uncertainties about water demands were considered in the mathematical model allowing to propose power reductions covering the potential risk of real-time water demand forecasting inaccuracy.Numerical results were discussed on a real water system in France, demonstrating both economic and ecological benefits.

VAPOR-LIQUID EQUILIBRIA FOR PROPYLENE -METHANOL-WATER SYSTEM

In this article VLE data for a ternary system (propylene-methanol-water) under 30～60 C,0. 3～0. 9 MPa with a mass ratio of methanol to water of 9:1, 8: 2, 7: 3 were determined with a static equilibrium still, and were correlated by using Peng-Robinson model. The average relative error ofpropylene concentration in liquid phase is 1. 46 %. The results indicate that the models are very suitablefor the ternary system and the data are reliable.

Sustainable water system of a green residential zone:demonstrated with a case of a campus construction project

The sustainable water system (SWS) was interpreted based on green residential zone associated codes issued by P.R.China and some other countries,and ecological principles.Its constitution,designing and engineering,and economic and environmental benefits were illustrated with a case of a campus construction project.The SWS incorporates divided nature drainage systems,grey water treatment and reuse technologies,rainwater decentralized collection and purification technologies,and water quality safeguard techniques for reclaimed water reused for landscaping.Application of the SWS is expected to gain remarkable economic and environmental benefits by reducing both the demand for municipal water supply and sewage discharge.

Lithium Behavior in Salt-water System Explored by Molecular Dynamics Simulation

The molecular dynamics simulation method was adopted to study the transient characteristics of Li^+,CO3^2-,and SO4^2- in Na^+,K^+,Li^+,Cl^-,and SO4^2-/H2O system.The composition of Na^+,K^+,Li^+,Cl^-,SO4^2- and CO3^2- was selected to optimize the initial structural model and conduct dynamic simulation.The mean azimuth shift and diffusion coefficient of Li^+,CO3^2-,and SO4^2- in the system,the radial distribution function and potential energy between Li^+ and -OW,SO4^2- and -OW as well as CO3^2- and -OW,and the dielectric constant of hydrogen bond were expounded and analyzed.At the same time,the Li enrichment behavior in the evaporation process of salt lake brine was analyzed based on the simulated data.The results show that the simulation results are in good agreement with the experimental values,which verifies that,compared with other ions,the crystallization of Li^+ and SO4^2- occurs earlier after reaching saturation.

The 3D simulation and optimized management model of groundwater systems based on eco-environmental water demand

Through the study of mutual process between groundwater systems and eco-environmental water demand, the eco-environmental water demand is brought into groundwater systems model as the important water consumption item and unification of groundwater抯 economic, environmental and ecological functions were taken into account. Based on eco-environmental water demand at Da抋n in Jilin province, a three-dimensional simulation and optimized management model of groundwater systems was established. All water balance components of groundwater systems in 1998 and 1999 were simulated with this model and the best optimal exploitation scheme of groundwater systems in 2000 was determined, so that groundwater resource was efficiently utilized and good economic, ecologic and social benefits were obtained.

Study on water environment restoration and urban water system healthy circulation

Studied on the law and interaction of hydrological cycle and social water circulation on the earth,it is pointed out that the water environment,water resources and water cycle are the unity of water movement.The roots of contemporary crisis are also analyzed.The strategy of water environment recovery and social water healthy cycle is proposed and applied in many cities,which has achieved good results.

Water System Management in Emergency Situations

This article deals with the issue of water system management and emergency management of water supply systems based on experience with the operation of water systems in EU （European Union） Member States. The options available for prevention/elimination of the hazard of limited drinking water supply to the public are described. Current climate and, in some countries, also the existing social conditions pose barriers to a smooth water supply to the public. Various hazards endangering the quality and amounts of water produced emerge. Since the risk of water supply outages due to natural or anthropogenic factors cannot be completely eliminated （for instance, hacker attacks pose a new threat to the water companies＇ control systems）, in other words, emergency situations where smooth water supply is disturbed cannot be ruled out, efforts must be made to at least minimise adverse impacts of such events on the users. Organisational and technical conditions minimising such hazards must be set up. A water production and distribution organization and management system must be introduced, which will be able to prevent and address such hazards and emergency situations. How to tackle this complex task in the real water system management conditions and to assure some minimal amount of water at least for strategic consumers is discussed in this article. The results of a water system operation risk analysis are presented, feasible methods to minimize such risks are described, and options to prevent and address such risks are proposed. A water company organisation and management system taking into account the possibility of development of emergency situations is set forth. Focus is on the use of a telemetric system as a system means that facilitates the prevention and possible addressing of any emergencies occurring during the operation of a water supply system.