超大直径聚乙烯管材的挤出技术

超大直径PE管材主要是指直径在600 mm以上的管材,主要应用在城市供水和市政排水等领域。随着PE100专用料甚至PE125专用料的越来越普遍的使用,其原料成本已接近PVC,生产的管道的重量和成本可以接近甚至低于PVC或其他管道。佛山市德仕威公司近期已完成了φ630 PE管生产线的市场推广,完成了φ800 PE管生产线的设计和制造任务。该公司生产的TWP系列PE大口径管材挤出生产线(最大口径达1000 mm)包括高速单螺杆挤出机、TWS2000系列螺杆、多履带式牵引机、行星式管材切断装置、大口径PE管材挤出模具。超大直径聚乙烯管材的挤出技术…     

PE100性能对聚乙烯燃气管道定向穿越施工的影响

与PE80相比,PE100在最小要求强度、耐慢速裂纹增长,耐快速裂纹扩展等性能方面有大幅提升。通过对PE管道定向穿越施工关键控制点的分析对比,得出PE100的优势。PE100材料性能的提升可以扩大PE管道在非开挖施工中的应用范围,同时也使燃气工程更经济和高效。     

PE80管材热板熔焊焊缝的慢速裂纹扩展行为

在80℃和2．4MPa恒应力拉伸的试验条件下，参照ASTMF1473—97标准，研究了国产燃气用PE80管材与其热板熔焊焊缝的慢速裂纹扩展(SCG)行为。研究表明二者SCG过程的δ—t关系均为同样的阶梯上升形态，这一形态是裂纹尖端区域材料的蠕变钝化与蠕变损伤积累过程相互转换的宏观表现。就所得试验结果的平均趋势而言，与PE80管材本身性能的比较，其熔焊焊缝的SCG抗力相对较差。     

纤维补强对燃气PE管材抗拉伸性能的影响

为了提高PE管材在北方冬季的抗拉伸性能,研究纤维补强方式对PE管材的抗拉伸性能的影响,进行PE管材试件拉伸试验。通过实验室中模拟不同环境温度,测量PE管材试件相应的抗拉伸性能,研究PE管材的抗拉伸性能随温度的变化情况。在PE管材外侧缠绕纤维补强材料后,测量在20℃和-25℃下PE管材试件的抗拉伸性能。结果表明,纤维补强方式能够增强燃气PE管材抗拉伸性能。     

浅谈PE燃气管道施工技术及应用

PE(聚乙烯)管道是以高密度聚乙烯为原料生产的管道输配系统,是城市供水及燃气输配管网领域中的一项管材新产品,是建设部“八五“重点推广运用的节能节材新产品.随着社会经济的发展,管道燃气逐渐在城市中普及.本文以某市管道燃气施工实践为例,介绍PE燃气管道施工技术,及运用.     

浅谈PE燃气管道施工技术及应用

PE(聚乙烯)管道是以高密度聚乙烯为原料生产的管道输配系统，是城市供水及燃气输配管网领域中的一项管材新产品，是建设部“八五”重点推广运用的节能节材新产品。随着社会经济的发展，管道燃气逐渐在城市中普及。本文以某市管道燃气施工实践为例，介绍PE燃气管道施工技术，及运用。     

寒冷地区冷水用PP-B、PP-R管材的选用

通过对PP-B、PP-R管材的化学结构和性能比较,阐述了这2种管材在用于建筑物内冷水管道时,使用上基本没有区别,但是耐低温冲击性能PP-B管材(脆化温度-20℃)比PP-R管材(脆化温度-10 ℃)好,PP-B管材更适合寒冷地区在进入冬季时进行建筑物内给水管道的施工.建议寒冷地区建筑物内冷水管道优先设计、使用PP-B管材.     

燃气用聚乙烯管材寿命预测

利用库存的燃气PE80聚乙烯管道为测试对象,对其氧化诱导时间、断裂伸长率、热失重进行试验测试,分析管材使用寿命。通过测试发现试样外层氧化诱导时间不满足GB 15558.1—2015《燃气用聚乙烯(PE)管道系统第1部分:管材》中氧化诱导时间大于20 min的要求。试样断裂伸长率满足要求。通过热失重试验,并拟合热失重达到50%的时间的自然对数与反应温度倒数的曲线,得出在20℃条件下,生产年份为2002年的管材剩余使用寿命约为12 a,截至2021年,已存放19 a,因此该PE管材的使用寿命约为31 a。     

城镇燃气聚乙烯管应用中相关问题研究

就我国聚乙烯(PE)管在燃气行业应用中存在的问题和如何保障PE燃气管道的安全进行了分析.可靠的原料、合理的设计、合格的施工、严格的运行管理是保障PE燃气管道应用安全和健康发展的基础.建议尽快提高全行业对PE材料的认知水平,加大市场监督力度,以保证我国燃气行业应用PE材料的健康有序发展.     

水业公司信息

宝硕股份新一代PVC给水管(PVC-M)隆重上市2006年12月10日,宝硕管材股份有限公司在北京举办新产品发布会,将自主开发的绿色无铅、高抗冲击的饮水用PVC-M管材正式推向市场,从而率先实现PVC管材品质的升级换代。脆性大、抗冲击性能差一直是PVC-U给水管材不能逾越的技术障碍。宝硕公司在PVC-U给水管材生产工艺的基础之上,通过对原料配方与生产工艺的改进而研发成功了PVC-M管材,其相关试验数据显示,PVC-M给水管的抗冲击性、韧性和抗裂纹增长性等均能与同口径的PE给水管材相媲美。与此同时,PVC-M给水管材还继承了PVC-U给水管强度…     

Evaluation of surface characteristics of laminated flooring

In this study, surface characteristics of commercially manufactured laminated flooring were evaluated. The surface roughness of samples consisting of high-density fiberboard (HDF) base and melamine resin saturated paper overlay was investigated. Here, 10 cm×10 cm samples of two types of panels were used for the experiments. A fine stylus technique was employed for the measurements. Three roughness parameters, namely average roughness (_Ra$R_{\mathrm{a}}$), mean peak to valley height (_Rz$R_{\mathrm{z}}$), and maximum roughness (_Rmax$R_{\max }$) were considered to determine roughness of the flooring panels. It was found that statistically significant difference existed between two types of samples as well as values taken along and across the sandmarks of the HDF and overlaid panels. Average _Ra$R_{\mathrm{a}}$, _Rz$R_{\mathrm{z}}$, and _Rmax$R_{\max }$ values for HDF were found as 2.73, 26.04, and 27.27 μm, respectively. Overlaid samples resulted in 15.6%, 26.0%, and 21.0% lower values of above parameters than those of HDF panels.     

Effect of some parameters on the formation of chloroform during chloramination of aqueous solutions of resorcinol

The effects of various factors (N/Cl ratio used to prepare monochloramine, monochloramine doses, pH and contact time) on the monochloramine demand and on the chloroform yield during chloramination of resorcinol have been investigated. Chloramination experiments were carried out at 24 ± 1 °C, at pH values ranging from 6.5 to 12 using a bicarbonate/carbonate buffer and preformed monochloramine solutions prepared at pH 8.5 with N/Cl ratios ([NH₄Cl]₀/[Total free Cl₂]₀ ranging from 1.0 to 150 mol/mol). Kinetic experiments ([Resorcinol]₀ = 5 or 100 μM, [NH₂Cl]₀/[Resorcinol]₀ = 20 mol/mol, pH = 8.5 ± 0.1) showed a slow increase of the monochloramine consumption with reaction time. The monochloramine demands after reaction times of 7 days ([Resorcinol]₀ = 100 μM) and 14 days ([Resorcinol]₀ = 5 μM) were equal to 8.5 mol of NH₂Cl/mole of resorcinol and were higher than the chlorine demands (≈7.3 mol/mol). Chloroform yields from monochloramination of resorcinol were lower than 8% (<80 mmol of CHCl₃/mole of resorcinol) and were less than the yields obtained by chlorination (0.9-0.95 mol/mol). Chloroform productions increased with increasing monochloramine dose and reaction time and decreased with increasing pH values within the pH range 6.5-10. Chloroform formation markedly decreased when the N/Cl ratio increased from 1 to 1.5 mol/mol and was suppressed at N/Cl > 100 mol/mol. The data obtained in the present work suggest that free chlorine released from monochloramine hydrolysis plays a significant role on the formation of chloroform during chloramination of resorcinol at N/Cl ratios close to unity (1.0 < N/Cl < 1.5).     

Modeling the effect of immobilization of microorganisms on the rate of biodegradation of phenol under inhibitory conditions

The main objective of this research is to model the effect of biodegradation process of phenol at high initial concentrations using a well known immobilization technique of the biomass. This work focused on testing the effect of activated carbon and clay while considering the diffusive internal mass transfer limitations. Biodegradation of phenol was performed by using enriched microorganisms from a compost of agricultural wastes. The average phenol biodegradation rate (uptake) of free biomass system was 235.3 mg g⁻¹ h⁻¹ at initial concentration range of 212-260 mg/L. However, the values for the systems of immobilized biomass in alginate and activated carbon (1 mm), alginate, activated carbon (4 mm), alginate, activated carbon and clay (1 mm) and alginate, activated carbon and clay (4 mm) were 64.9, 27.6, 27.5, and 8 mg g⁻¹ h⁻¹ respectively. The effective diffusion factors in different matrix were obtained using an intra-particle diffusion-based mathematical model. Diffusion limitation was observed when the matrix contained clay in addition to activated carbon. The diffusion coefficient was decreased from 1.6 × 10⁻⁸ to 1.2 × 10⁻⁹ cm²/s when clay was added to the matrix of 1 mm of alginate and activated carbon. Also, slight differences between the diffusion factors were observed for larger beads. The combination of clay and AC contributes to better mineralization of phenol at high concentrations. This could be attributed to the synergism of both additives.     

Photochemical generation of reactive species upon irradiation of rainwater: Negligible photoactivity of dissolved organic matter

This paper focuses on the study of the photochemical activity of dissolved organic matter present in rainwater. Formation rates of the reactive species hydroxyl radical (OH^•), singlet oxygen (¹O₂) and dissolved organic matter triplet states (³DOM^?) were determined by irradiation (UV-A) of wet-only rainwater samples collected in Turin (Italy) in the presence of specific scavengers (benzene, furfuryl alcohol and phenol, respectively). Photo-formation rates of OH^• (≈ 3 · 10⁻¹¹ M s⁻¹) and ¹O₂ (≈ 10⁻¹⁴ M s⁻¹) were lower (1 or 2 orders of magnitude) or largely lower (4 to 10 orders of magnitude) than those determined for fog and cloud samples in previous studies. ³DOM^? formation rate values were either negligible or quite low (≈ 10⁻¹² M s⁻¹) by comparison with those evaluated for surface water samples. Deduced steady-state [OH^•] were in the same range as those reported for fog samples in the literature (8.7 · 10⁻¹⁶ to 1.5 · 10⁻¹⁵ M), while [¹O₂] was often several orders of magnitude lower and, therefore, could be considered as negligible. Nitrite (NO₂⁻) constituted the main source of OH^• (69 ± 21 to 138 ± 36%), and the deduced contribution of DOM was low or nil. All the results obtained in this study tend to demonstrate that DOM (including HUmic LIke Substances, HULIS) present in rainwater is poorly or not photoactive. Therefore, there could be considerable difference between rainwater DOM (HULIS included) and the organic matter present in surface waters, particularly the humic substances, as far as the photochemical activity is concerned.     

Evaluation of hydro-mechano-chemical behaviour of bentonite-sand mixtures

Bentonite-sand mixtures are widely used in engineering barrier of deep geological disposal of high-level radioactive nuclear waste and anti-seepage barrier of civil geotechnical engineering. Under the action of groundwater solution infiltration and external stress, the hydro-mechanical (HM) behaviour of bentonite-sand mixtures, i.e. the swelling characteristics and permeability, will change. Once the anti-seepage and filtration effect is weakened or lost, the pollutants will spread to the biosphere. Therefore, it is necessary to study the swelling characteristics and permeability of bentonite-sand mixtures under coupled mechano-chemical (MC) effect and to establish corresponding prediction model. For this reason, swelling tests under salt solution with different concentrations are conducted on pure bentonite and its mixtures with 30%, 70% and 90% sand contents, the compression tests are carried out on saturated samples, and the saturated permeability coefficient k of the sample under each load is calculated by Terzaghi's one-dimensional consolidation theory. The concepts of true effective stress p_e, montmorillonite void ratio e_m and critical sand content α_s are introduced to determine the e_m-p_e relationship and finally the k-e_m relationship of bentonite-sand mixtures. It is found that when the sand content α ≤ α_s, the e_m-p_e relationship of the mixture is linear and independent of the salt solution concentration, and when α > α_s, the e_m-p_e relationship of bentonite-sand mixture is bi-linear with the true effective deviatoric stress p_esα as the intersection. In addition, the e_m-k relationship also shows the linear trend when α ≤ α_s, and the slope of the line increases with the increase of the salt solution concentration. When α > α_s, the k-e_m relationship will deviate from the linear relationship. Moreover, the larger the sand content is, the farther the deviation is. On the basis of summing the regularity, a model for predicting the HM behaviour of bentonite-sand mixture under the coupled MC effect is proposed. By comparing the swelling and permeability test results with model prediction results of different types of bentonite and its sand mixtures, the predictive model is verified. The study on the HM behaviour of bentonite-sand mixtures under salt solution infiltration and the model establishment can provide experimental and theoretical basis for the design and construction of anti-seepage engineering by bentonite-sand mixtures.     

Enhanced ignition of biomass in presence of NOx

Accumulation of combustible biomass residues on hot surfaces of processing machineries can pose fire hazards. In addition, the presence of nitrogen oxides (NO_x) from plant equipment alters the local conditions, aggravating the propensity for low temperature ignition risks. This study presents an experimental study on a relative effect of NO_x on ignition temperature of morpholine, an important surrogate of biomass, to reveal the sensitising role of NO_x in ignition of biomass fuels and to gain mechanistic insights into the chemical aspect of this behaviour in fire. The experiments employed a flow-through tubular reactor, operated at constant pressure and residence time of 1.01 bar and 1.0 s, respectively, and coupled with a Fourier-transform infrared spectroscope. For a representative fuel-rich condition (Φ=1.25), the concentration of NO_x as small as 0.06% lowers the ignition temperature of morpholine by 150 °C, i.e., from approximately 500 °C to 350 °C. The density functional theory (DFT) calculations performed with the CBS-QB3 composite method, that comprises a complete basis set, characterised the dynamics and energies of the elementary nitration reactions. We related the observed reduction in ignition temperature to the formation of unstable nitrite and nitrate adducts, as the result of addition of NO_x species to morphyl and peroxyl radicals. Furthermore, the reaction of NO_x with low-temperature hydroperoxyl radical leads to the formation of active OH species that also propagate the ignition process. The present findings quantify the ignition behaviour of biomass under NO_x–doped atmospheres. The result is of great importance in practical applications, indicating that safe operation of wood-working plants requires avoiding trace concentration of NO_x within the vicinity of biomass residues. This can be facilitated by proper (and separate) venting of engine exhausts.     

最大动态剪力模数次增加率之预测

正规化最大动态剪力模数次增加率Ｎ＿ｇ之观念虽然已被提出，但是其影响因素之精确指标仍待后人研究。因此，本文深入探讨粘性土壤在现场有效覆土压力长期作用下，时间效应对最大动态剪力模数Ｇ＿（ｍａｘ）之影响，并与剪力波速回归公式作比较，以期达到预测Ｎ＿ｇ值之目标。在一般物理性质对时间效应之影响研究中，Ｎ＿ｇ值有随塑性指数Ｉ＿ｐ值增加之趋势，而平均颗粒粒径Ｄ＿（５０）愈小时，Ｎ＿ｇ值愈大，且重模试体之Ｎ＿ｇ值较原状试体为小。由本文之Ｎ＿ｇ－Ｉ＿ｐ－Ｃ值之关系可知，粘土含量Ｃ相同时，若Ｉ＿ｐ值愈大，则Ｎ＿ｇ愈大。而Ｎ＿ｇ－Ｉ＿ｐ－Ｃ＿ａ值三者之关系中，若二次压缩指数Ｃ＿ａ值相同，则Ｉ＿ｐ值愈大时，Ｎ＿ｇ值愈大。     

Influence of feed concentration on the kinetics of biodegradation of phenol in a continuous stirred reactor

The rate of phenol degradation by activated sludge was studied in a completely mixed continuous-flow reactor with sludge recycle, operated at steady-state conditions at 20°C. Monod kinetics was followed when the influent concentration (C_s°) was kept constant. When using different C_s° levels, the phenol removal rate was found to have an inverse dependence on C_s°. It is suggested that this kinetic anomaly is due to inhibition of the biooxidation by some secondary reaction product(s). A kinetic model based on this concept is able to interpret experimental facts.     

Determination of sorption of seventy-five pharmaceuticals in sewage sludge

Sorption of 75 active pharmaceutical ingredients (APIs) to three different types of sludge (primary sludge, secondary sludge with short and long sludge age respectively) were investigated. To obtain the sorption isotherms batch studies with the APIs mixture were performed in four nominal concentrations to water containing 1 g of sludge. The range of APIs concentrations was between ng L⁻¹ to μg L⁻¹ which are found in the wastewater effluents. Isotherms were obtained for approximately 45 of the APIs, providing distribution coefficients for linear (K_d), Freundlich (K_f) and Langmuir (K_L) isotherms. K_d, K_f and K_L ranging between 7.1 × 10⁴ and 3.8 × 10⁷, 1.1 × 10⁻² and 6.1 × 10⁴ and 9.2 × 10⁻³ and 1.1 L kg⁻¹, respectively. The obtained coefficients were applied to estimate the fraction of APIs in the water phase (see Abstract Graphic). For 37 of the 75 APIs, the predicted presence in the liquid phase was estimated to >80%. 24 APIs were estimated to be present in the liquid phase between 20 and 80%, and 14 APIs were found to have <20% presence in the liquid phase, i.e. high affinity towards sludge. Furthermore, the effect of pH at values 6, 7 and 8 was evaluated using one way ANOVA-test. A significant difference in K_ds due to pH changes were found for 6 of the APIs (variation 10-20%).