Specific Energy Consumption Analysis Model and Its Application in Typical Steel Manufacturing Process

Theoretical minimum and actual specific energy consumptions （SEC） of typical manufacturing process （SMP） were studied. Firstly, a process division of a typical SMP in question was conducted with the theory of SEC analysis. Secondly, an exergy analysis model of a subsystem consisting of several parallel processes and a SEC analysis model of SMP were developed. And finally, based on the analysis models, the SEC of SMP was analyzed by means of the statistical significance. The results show that the SEC of typical SMP comprises the theoretical minimum SEC and the additional SEC derived from the irreversibility~ and the SMP has a theoretical minimum SEC of 6.74 GJ/t and an additional SEC of 19.32 GJ/t, which account for 25.88% and 74.12% of the actual SEC, respectively.

Experimental technique to analyze the influence of cutting conditions on specific energy consumption during abrasive metal cutting with thin discs

Specific energy consumption is an important indicatorfora better understanding of the machinability of materials.The present study aims to estimate the specific energy consumption for abrasive metal cutting with ultrathin discs at comparatively low and medium feed rates.Using an experimental technique,the cutting power was measured at four predefined feed rates for S235JR,intermetallic Fe-Al(40%),and C45K with different thermal treatments.The variation in the specific energy consumption with the material removal rate was analyzed through an empirical model,which enabled us to distinguish three phenomena of energy dissipation during material removal.The thermal treatment and mechanical properties of materials have a significant impact on the energy consumption pattern,its corresponding components,and cutting power.Ductile materials consume more specific cutting energy than brttle materials.The specific cutting energy is the minimum energy required to remove the material,and plowing energy is found to be the most significant phenomenon of energy dissipation.

Analysis of minimum specific energy consumption and optimal transport concentration of slurry pipeline transport systems

Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transportation systems.Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop(SJTU-HMSPD)pipeline-resistance-calculation model,the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system.The said system demonstrates a uniformity coefficient in the 1.26–7.98 range,median particle size of 0.075–4 mm,particle volume concentration of 10–60%,and pipeline diameter of 0.203–0.8 m.The results obtained were successfully verified against existing experimental data.The influence of parameters,such as particle-gradation uniformity coefficient,median particle size,pipe diameter,and particle volume concentration,on the SPC were analysed.The results revealed that the greater is the uniformity coefficient,the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant,median particle size slurry.As observed,the optimal transport concentration for broad-graded sand equalled approximately 48%.These results supplement the conclusions of existing research,indicating that the optimal transport concentration is approximately 30%and provides theoretical support for high concentration transportation of broad graded slurry.

Rock breaking performance of the newly proposed unsubmerged cavitating abrasive waterjet

To improve the rock breaking ability, cavitating waterjet and abrasive waterjet are combined by using a coaxial low-speed waterjet generated around the periphery of a high-speed abrasive waterjet, and a new type of waterjet called unsubmerged cavitating abrasive waterjet(UCAWJ) is thus produced. The rock breaking performance of UCAWJ was compared with submerged cavitating abrasive waterjet(SCAWJ)and unsubmerged abrasive waterjet(UAWJ) by impinging sandstone specimens. Moreover, the effects of jet pressure, standoff distance, abrasive flow rate and concentration were studied by evaluating the specific energy consumption, and the area, depth, and mass loss of the eroded specimen. The results show that the artificially generated submerged environment in UCAWJ is able to enhance the rock breaking performance under the same operating parameters. Furthermore, the rock breaking performance of UCAWJ is much better at higher jet pressures and smaller standoff distances when compared with UAWJ. The greatest rock breaking ability of UCAWJ appears at jet pressure of 50 MPa and standoff distance of 32 mm, with the mass loss of sandstone increased by 370.6% and the energy dissipation decreased by 75.8%. In addition, under the experimental conditions the optimal abrasive flow rate and concentration are 76.5 m L/min and 3%, respectively.

Characteristic and correlation analysis of influent and energy consumption of wastewater treatment plants in Taihu Basin

The water quality and energy consumption of wastewater treatment plants(WWTPs)in Taihu Basin were evaluated on the basis of the operation data from 204 municipal WWTPs in the basin by using various statistical methods.The influent ammonia nitrogen(NH3-N)and total nitrogen(TN)of WWTPs in Taihu Basin showed normal distribution,whereas chemical oxygen demand(COD),biochemical oxygen demand(BOD5),suspended solid(SS),and total phosphorus(TP)showed positively skewed distribution.The influent BOD5/COD was 0.4%-0.6%,only 39.2%SS/BOD5 exceeded the standard by 36.3%,the average BOD5/TN was 3.82,and the probability of influent BOD5/TP>20 was 82.8%.The average energy consumption of WWTPs in Taihu Basin in 2017 was 0.458 kWh/m^3.The specific energy consumption of WWTPs with a daily treatment capacity of more than 5×10^4 m^3 in Taihu Basin was stable at 0.33 kWh/m^3.A power function relationship was observed between the reduction in COD and NH3-N and the specific energy consumption of pollutant reduction,and the higher the pollutant reduction is,the lower the specific energy consumption of pollutant reduction presents.In addition,a linear relationship existed between the energy consumption of WWTPs and the specific energy consumption of influent volume and pollutant reduction.Therefore,upgrading and operation with less energy consumption of WWTPs is imperative and the suggestions for Taihu WWTPs based on stringent discharge standard are proposed in detail.

Fertilizer drawn forward osmosis as an alternative to 2nd pass seawater reverse osmosis: Estimation of boron removal and energy consumption

Agriculture is the largest consumer of freshwater.Desalinated seawater is an important alternative water source for sustainable irrigation.However,some issues of the current desalination technology hinder its use for agriculture irrigation,including low boron removal and high energy consumption.This study systematically explored the feasibility of employing fertilizer drawn forward osmosis(FDFO)as an alternative to 2nd pass reverse osmosis(RO)by considering the boron removal performance and specific energy consumption(SEC).Different operating conditions were investigated,such as the boron and NaCl concentrations in feed solution(FS),draw solution(DS)concentration,pH,the volume ratio of FS to DS,membrane orientation,flow rate,and operating temperature.The results indicated that a low boron concentration in FS and high DS pH(pH=11.0)decreased the boron solute flux,and led to low final boron concentration in the DS.The other operating conditions had negligible influence on the final DS boron concentration.Also,a lower flow rate and higher specific water flux with certain permeate water volumes were conducive to reducing the SEC of the FDFO process.Overall,our study paves a new way of using FDFO in irrigation,which avoids the phytotoxicity and human health risk of boron.The results show the potential of FDFO as an alternative to 2nd pass RO for irrigation water production.

Studies of ultrasound disintegration of residual sludge and its energy consumption in water treatment of petrochemical plant

To investigate the influence of ultrasound pretreatment on sludge anaerobic digestion,the ultrasound disintegration of residual sludge in water treatment of petrochemical plant was studied,and the mechanisms of ultrasound and medium were introduced.Experimental results indicate that ultrasound cavitation induces the rise of sludge temperature,which improves ultrasound disintegra-tion on sludge.U1trasound pretreatment can advance observ-ably the quantity of chemical oxygen demand in sludge supernatant fluid(SCOD),which increases with ultrasound intensity and sonication time.The degree of ultrasound disintegration increases with the specific energy input.When the specific energy input is l0000 kJ/kg of total dry solids,the degree of ultrasonic sludge disintegration reaches 40%.

Life Cycle Assessment of Biodegradable Plastics

Many industrial products made from fossil fuels cause the problems of global warming,depletion of fossil fuel resources and decrease of the land by landfill.In this report,the amounts of CO2 emissions as the environmental load and the specific energy consumptions as the depletion of fossil fuel resources of biodegradable plastics and conventional plastic as food trays are compared using life cycle assessment methodology.The amount of CO2 emission of PHB(poly(3-hydroxybutyrate-co-4-hydroxybutyrate)) tray was the smallest among those of trays of other plastics.The specific energy consumption of SPCL(starch/polycaprolactone) was the smallest among those of trays of other plastics.It clearly reveals that the utilization of the biodegradable plastics is an effective way of alternatives of the conventional plastics.