Advanced Materials Research Vols. 236-238

Abstract: A new type of corrugated tube based on sine function is proposed by introducing a parameter of sine camber. The heat transfer and flow around sinusoidal corrugated tubes with different sine camber e are investigated in this paper. Computational Fluid Dynamics (CFD) was used to analysis flow state and sine camber of tube influence on the heat transfer and flow, a correlation equations of Nu (Nusselt) =f(Re) is given. At last, the theoretical comparative analysis with field synergy principle is carried out for the heat transfer and flow resistance in smooth tube and sinusoidal corrugated tube. The results show that the experiment basically tallies with the value of numerical calculation of laminar flow. In the range of 500 < Re < 1000, flow resistance coefficient has great decrease extent, while low resistance coefficient has small decrease extent of 1500 < Re < 2300. The effect of field synergy is poor in the smooth tube, which is opposite to that in sinusoidal corrugated tube, and it can improve the efficiency of around 2.7 times.

Abstract: To study the bleaching mechanisms of H₂O₂ bleaching, H₂O₂ displacement bleaching and H₂O₂ /TAED bleaching, three kinds of lignin bleached with above processes were obtained. Three types of treated Populus nigra L lignins structure were identified and the functional groups were quantitied by FTIR. In contrast, the deacetylation and the breakage of ester bonds in H₂O₂/TAED bleaching system was much more significant. The total carbonyl group of H₂O₂ bleached lignin decreased 6.6% while displacement bleached lignin and H₂O₂/TAED bleached lignin decreased 9.2% and 15.8% respectively. The PT bleaching process had stronger oxidability to destroy the syringyl units in lignin. The breakage of ether bonds and alcoholic hydroxyl dehydration in side chain increased after bleaching. In contrast, the stronger destroyed effection on guaiacyl dialkyl ether bond with PT bleaching processes. The conclusions obtained may interpret H₂O₂ displacement bleaching and H₂O₂/TAED bleaching systems have better bleaching efficiency than H₂O₂ bleaching system.

Abstract: The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, and turbulence level (velocity of pulp flow) on old book paper deinking efficiency was studied by using a high-consistency laboratory pulper and a laboratory deinking cell. The optimized flotation conditions were: flotation consistency 1.2%, 50°C, 6min, air to pulp ratio 40%, velocity of pulp flow 5.0m/s. By using the optimized flotation conditions, the deinked pulp brightness could reach 77.01%ISO, 9.69%ISO higher than that of the control, the effective residual ink concentration was 175.26 mg/kg, which less than 437.84mg/kg of the control, deinking efficiency was up to 59.97%. After washing process, pulp brightness could reach 84.27%ISO, the effective residual ink concentration was 93.71 mg/kg, deinking efficiency was up to 78.60%.

Abstract: The selectivity of delignification is disappointing in the conventional intensified alkali extraction by oxygen and H₂O₂. To improve the properties of the conventional intensified alkali extraction, the gradient intensified alkali extraction by oxygen-containing bleaching agents was presented, and effects of treatment conditions on properties of gradient intensified alkali extraction of kraft pulp by oxygen and/or H₂O₂ were investigated. In DE_PD bleaching sequence, the optimal dosage of H₂O₂ in E_P stage is 1.5% with higher brightness and lower loss in viscosity of bleached pulp. The addition time of H₂O₂ is better after 20 min of alkali extraction in DE/PD sequence to facilitate bleaching function of H₂O₂. In DP/ED sequence, the brightness is highest when alkali extraction carried through after 20 min of H₂O₂ bleaching. In E_O stage, the optimal dosage of NaOH is 5.0% considering delignification and bleaching efficiency. As to alkali extraction intensified by oxygen and H₂O₂, the optimum dosage of H₂O₂ is 1.0%. Gadient intensified alkali extraction with oxygen and/or H₂O₂ was adopted for further bleaching and delignification, which can increase the brightness and selectivity of delignification by subtly adjusting the parameters.

Abstract: High consistency refining (HCR) and low consistency refining (LCR) of unbleached Masson’s pine kraft pulps for sack paper were studied in this article. The properties of their refined pulp and handsheet were analyzed comparatively. The results showed a high consistency refining was more suitable for sack paper with unbleached Masson’s pine kraft pulp than a low consistency refining. High consistency refining is of advantage to retain the fiber length. The tear index of the handsheet of high consistency refining were higher than that of low consistency refining. The TtensileT TenergyT Tabsorption (TEA)T index and air permeability of the handsheet of high consistency refining which were crucial properties of sack papers were better, though higher tensile index could be obtained with low consistency refining.

Abstract: In this paper, the process of acid extracting pectin from Guangyechu white bast and subsequent ammonium sulfate pulping was optimized by condition test. Under optimal conditions, the pectin yield was 3.99%, the screened pulp yield was 52.61%, KMnO₄ value was 9.84 and whiteness was 51.7%ISO. And chemical compositions of Guangyechu white bast in each treatment stage were compared and analyzed.

Abstract: In this paper, the effect of microwave treatment on the hydrogen peroxide bleaching of Soda-AQ wheat-straw pulp was investigated. The results showed that microwave treatment could increase the brightness of the hydrogen peroxide bleached pulp. The fiber coarseness of microwave enhancing peroxide bleached pulp was higher than that of the peroxide bleached pulp. However, the arithmetic average fiber length, the length weighted average fiber length and weight weighted average fiber length of the former was lower than that of the latter. Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD) spectra showed that CrI(%) crystallinity of microwave enhancing peroxide bleached pulp was similar as that of the peroxide bleached pulp but all higher than that of the Soda-AQ wheat-straw pulp. N·O′KI infra-red crystalline index of microwave enhancing peroxide bleached pulp were lower than that of the peroxide bleached pulp. The FTIR spectra of lignin showed that the microwave treatment had some influences on the methoxyl and phenolic group in lignin.

Abstract: The largest proportion of energy consuming is the operations of separation in chemical industry, and the energy consumption of the distillation is the highest in separation. Therefore, it is very important to research energy-saving issues of the process of distillation in today's circumstances of the energy shortage. This article describes the model of the heat pump distillation column,and its characteristics, uses static simulation programs to simulate operating conditions in the same pressure for the propylene-propane material system, and studys effects of the different feed states on the energy-saving of heat pump distillation column. The results will be compared with the conventional distillation column, and it was showed that for propylene-propane system, the heat pump distillation column is more remarkable than the conventional distillation column in energy savings, and its energy saving rate can reach 56%.

Abstract: The residues from wheat straw pulping mainly include uncooked chips and fiber bundles. In order to achieve high quality pulp, the residues require removal from the system. It was not necessary that the residues were re-cooked because of its high contents of non-cellulosic constituent. The achievement of low density foamed buffer material with the residues of wheat straw pulping would make the second pollution problem of the residues be solved, and achieve a replacer of foamed plastic material. The paper discussed the producing techniques of foamed buffer material with the residues of wheat straw pulping. The result showed that the best foamed properties of the residues were achieved with proper dosage of natural bonding agent like wheat flour, inorganic foamed agent, crosslink agent, and proper foamed temperature. The density and compression of foamed buffer material with the residues of wheat straw pulping were achieved with 60 kg /m³ and 60 kPa respectively at the optimum foaming condition.

Abstract: The focus of this study is to investigate the effect of carboxylated styrene-butadiene rubber (SBR) latex on the dynamic rheologcial properties of paper coating suspensions modified with nanosized particles. The elastic storage modulus G′ and the viscid loss modulus G′′ are used to evaluate the dynamic rheologcial properties of paper coating suspensions. The effects of different amount carboxylated styrene-butadiene rubber latex on the flow parameters of paper coating suspensions are comparatively presented. It is shown that the dynamic elastic storage modulus G′ and viscid loss modules G′′ of paper coating suspensions increase with the SBR content change from 13% to 18%. The dynamic rheologcial properties are related to the strength of the network structure of paper coating suspensions. It is also found that the elastic storage modulus G′ of paper coating suspensions is larger than viscid loss modulus G′′, which indicates that paper coating suspensions in this investigation all behave like a viscoelastic solid.