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%).

Laccase Immobilized on Mesoporous Silica Materials and Its Corrosion Inhibition Performance in Circulating Cooling Water System

Mesoporous SiO_2 microspheres were synthesized using the sol-gel method and were characterized by TEM, FT-IR and BET techniques. The diameter of the microspheres is about 100—150 nm, and the average mesopore diameter is 2.55 nm, while the specific surface area is 1 088.9 m2/g. Mesoporous SiO_2 microspheres adsorb glutaraldehyde and immobilize laccase by means of the aldehyde group in glutaral which can react with the amidogen of laccase. The immobilization conditions were optimized at a glutaraldehyde concentration of 0.75%, a crosslinking time of 8 h, a laccase concentration of 0.04 L/L and an immobilization time of 10 h. When diesel leakage concentration was 80 mg/L, the highest corrosion inhibition efficiency of immobilized laccase reached 49.23%, which was slightly lower than the corrosion inhibition efficiency of free laccase(59%). The diesel degradation ratio could reach up to 45%. It has been proved that the immobilized laccase could degrade diesel to inhibit corrosion.

Removal of kathon by UV-C activated hydrogen peroxide:Kinetics,mechanisms,and enhanced biodegradability assessment

Kathon(CMI-MI),a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one(CMI)and 2-methyl-4-isothiazolin-3-one(MI),was extensively used in industry as a nonoxidizing biocide or disinfectant.However,it would show adverse effects on aquatic life when it is discharged into surface water.In this study,the removal performance,parameter influence,degradation products and enhancement of subsequent biodegradation of CMI-MI in UV/H_(2)O_(2)system were systematically investigated.The degradation rate of CMI-MI could reach 90%under UV irradiation for 20 min when the dosage of H_(2)O_(2)was 0.3 mmol·L^(–1).The DOC(dissolved organic carbon)mineralization rate of CMI-MI could reach 35%under certain conditions([H_(2)O_(2)]=0.3 mmol·L^(–1),UV irradiation for 40 min).kobs was inversely proportional to the concentration of CMI-MI and proportional to the concentration of H_(2)O_(2).The degradation rate of CMIMI was almost unchanged in the pH range from 4 to 10.Except the presence of CO_(3)^(2-)inhibited the removal rate of CMI-MI,SO_(4)^(2-),Cl^(-),NO_(3)^(-),and NH_(4)^(+) did not interfere with the degradation of CMI-MI in the system.It was found that UV/H_(2)O_(2)system had lower energy consumption and more economic advantage compared with UV/PS system by comparing the EEO(electric energy per order)values under the same conditions.Two main organic products were identified,namely HCOOH and CH_(3)NH_(2).There’s also the formation of Cl^(-)and SO_(4)^(2-).After UV and UV/H_(2)O_(2)photolysis,the biochemical properties of CMI-MI solution were obviously improved,especially the UV/H_(2)O_(2)treatment effect was better,indicating that UV/H_(2)O_(2)technology is expected to combine with biotechnology to remove CMI-MI effectively and environmentally friendly from wastewater.