预热自热高温好氧消化工艺处理市政污泥的研究

用自行设计的预热自热高温好氧消化工艺系统处理市政污泥,采用间歇式运行方式,对不同的进泥浓度、搅拌速率、曝气量、固体停留时间条件下的污泥稳定化效果进行了单因素分析研究,获得最佳工艺参数,在此基础上,对污泥稳定化和无害化效果进行了评价,同时对消化后污泥的脱水性能、总氮、总磷、氨氮、总有机碳和pH值进行了测试分析。结果表明,当进泥含固率为4%～6%、进泥挥发性有机物浓度为(31.9～42.1)g/L、搅拌速率为(90～100)r/min、曝气量为(0.06～0.08)m3/h、固体停留时间为10d时,污泥稳定化效果最好,反应器内温度可维持在55～57℃,对挥发性有机物的去除率平均达到52.8%,此时,病原菌的灭活率达到100%,出泥达到了美国环保局规定的A级生物固体(污泥)的标准;在此最佳工艺条件下发现消化后的污泥脱水性能变差,而总氮、总磷、氨氮、总有机碳和pH值升高,这是由于在消化过程中产生的溶胞现象所致。

污泥预热自热高温好氧消化工艺中试

建立一套有效容积为1020 L的单级污泥预热高温好氧消化的中试工艺,在进泥含固率为6%,VSS浓度为42.1 g/L,搅拌速率为150～160 r/min,曝气量为2.0～2.2 m3/h的工艺参数条件下,45℃下预热24 h,污泥在消化进行到第10 d时已达到稳定化和无害化的标准,出泥达到A级生物固体的标准,并发现VSS和DHA的降解率与污泥停留时间和反应温度的乘积密切相关,当乘积为500(℃.d)以上时,污泥才能达到稳定化的标准。

污泥预热自热高温好氧消化工艺中试

建立一套有效容积为1020 L 的单级污泥预热高温好氧消化的中试工艺,在进泥含固率为6%,VSS浓度为42.1 g/L,搅拌速率为150～160 r/min,曝气量为2.0～2.2 m^3/h 的工艺参数条件下,45℃下预热24h,污泥在消化进行到第10d 时已达到稳定化和无害化的标准,出泥达到 A 级生物固体的标准,并发现 VSS 和DHA 的降解率与污泥停留时间和反应温度的乘积密切相关,当乘积为500(℃·d)以上时,污泥才能迟到稳定化的标准。

预热自热高温好氧消化过程中污泥各项性能指标的变化研究

对预热自热高温好氧消化过程中污泥各项性能指标的变化进行了研究,研究项目包括污泥的p H值、氧化还原电位(ORP)、总氮(TN)、氨氮(NH4+-N)、总磷(TP)、蛋白质、挥发性有机酸(VFA)和总有机碳(TOC)。结果表明,以上研究指标均有不同程度的变化,反应了消化后污泥性质的变化,为研究消化后污泥的用途提供了有益的参考。

Hot corrosion behavior of Ni-xCr-6.8Al based alloys

The hot corrosion behaviors of as-cast and preoxidized Ni-xCr-6.8Al based alloys in the mixture of Na2SO4＋25% NaCl at 873 K were studied. The results show that the mass loss of Ni-xCr-6.8Al based alloys decreases with the increase of Cr content. Preoxidation improves the resistance to corrosion regardless of the concentration of Cr. The kinetics of as-cast Ni-12Cr-6.8Al and Ni-16Cr-6.8Al based alloys fits the parabolic law well, while that of the as-cast Ni-20Cr-6.8Al based alloy fits the power law. The kinetics of all the preoxidized samples obey the logarithmic law. The mechanism of the as-cast alloys can be well explained by the acid-base melting model. The behavior of the preoxidized alloys is found to be mainly determined by the properties of the oxide layer formed during the preoxidation to a large extend.

Hot corrosion behavior of Ni–16Cr–xAl based alloys in mixture of Na_2SO_4-NaCl at 600 ℃

The hot corrosion behaviors of Ni–16Cr–xAl（x=4.5%, 6.8%, 9.0%, mass fraction） based alloys in Na2SO4–25% NaCl molten salts at 600 °C were investigated. The effects of pre-oxidation and Al content on the resistance to hot corrosion were examined. The hot corrosion resistance of Ni–16Cr–xAl based alloy with Al addition from 4.5% to 9.0% increases with increasing Al content. The alloy with Al content of 9.0% shows the highest hot corrosion resistance among the examined alloys because more β–NiAl phases are obtained to sustain the Al2O3 scale repaired during hot corrosion. Pre-oxidized specimens have a superior hot corrosion resistance compared with the as-cast specimens, due to a protective oxide scale formed after pre-treatment.

如何提高切割坡口质量

本文对在不依赖技术熟练程度上,如何提高管材坡口切割质量,进而提高焊接质量,减少焊材损耗,提高工作效率进行了论述。管线进行改造,由于管线直径较大,壁较厚,为了保证焊接质量,需要对焊道多层焊接,必须对管道进行坡口加工。但因为身体、环境、技术经验等原因,易造成割口参疵不齐,坡口角度不均等缺陷,直接影响焊接质量。我通过请教老师傅,反复摸索试验,制作出了"套筒式坡口角度尺",较好的解决了上述问题,提高了切割坡口的质量,从而保证了焊接质量,也提高了工作效率。

钢板数控切割效率及材料利用率研究

2011年,我国用于切割焊接产业用钢材近3亿吨,但在使用过程中浪费钢材总量比发达国家多10%,即浪费钢材总量3000万吨。因此提高材料利用率和提高切割效率,是企业降本增效、提高竞争力的重要手段。徐州中材装备重型机械有限公司是中材装备集团有限公司旗下以生产水泥机械为主的专业化机械制造企业,年产量3万吨,其中每年钢板消耗将近2.3万吨,材料利用率低。

Effects of vacuum pre-oxidation process on thermally-grown oxides layer of CoCrAlY high temperature corrosion resistance coating

The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto the nickel-based superalloy substrate by high velocity oxygen fuel（HVOF）.It suggests that the TGO usually consists of a great number of chromium oxides,cobalt oxides and spinel oxides besides alumina during the initial period of the high temperature oxidation if the specimens are not subjected to the appropriate vacuum pre-oxidation process.Furthermore,the amount of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides are usually formed under the conditions of higher partial pressure of oxygen during the initial period and the lower partial pressure of oxygen during the subsequent period of the isothermal oxidation.After the appropriate vacuum pre-oxidation process,the TGO is mainly composed of alumina that contains lower Y element,while alumina that contains higher Y element sporadically distributes,and the spinel oxides cannot be found.After a longer period of the isothermal oxidation,a small amount of porous CoCr2O4 and the chrome oxide sporadically distribute near the continuous alumina.Additionally,after the appropriate vacuum pre-oxidation process,the TGO growth rate is relatively slow.

Ischemic preconditioning inhibits development of edematous cerulein-induced pancreatitis: Involvement of cyclooxygenases and heat shock protein 70

AIM： To determine whether ischemic preconditioning （IP） affects the development of edematous cerulein-induced pancreatitis and to assess the role of cyclooxygenase-1 （COX-l）, COX-2, and heat shock protein 70 （HSP 70） in this process. METHODS： In male Wistar rats, IP was performed by damping of celiac artery （twice for 5 min at 5-min intervals）. Thirty minutes after IP or sham operation, acute pancreatitis was induced by cerulein. Activity of COX-1 or COX-2 was inhibited by resverabol or rofecoxib, respectively （10 rng/kg）. RESULTS： IP significantly reduced pancreatic damage in cerulein-induced pancreatitis as demonstrated by the improvement of pancreas histology, reduction in serum lipase and poly-C ribonuclease activity, and serum concentration of pro-inflammatory interleukin （IL）-1β. Also, IP attenuated the pancreatitis-evoked fall in pancreatic blood flow and pancreatic DNA synthesis. Serum level of anti-inflammatory IL-10 was not affected by IP. Cerulein-induced pancreatitis and IP increased the content of HSP 70 in the pancreas. Maximal increase in HSP 70 was observed when IP was combined with cerulein-induced pancreatitis. Inhibition of COXs, especially COX-2, reduced the protective effect of IP in edematous pancreatitis. CONCLUSION： Our results indicate that IP reducespancreatic damage in cerulein-induced pancreatitis and this effect, at least in part, depends on the activity of COXs and pancreatic production of HSP 70.

Mechanism of high pressure roll grinding on compression strength of oxidized hematite pellets

The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.

Effect of exhaust gas recirculation and intake pre-heating on performance and emission characteristics of dual fuel engines at part loads

Achieving simultaneous reduction of NOx,CO and unburned hydrocarbon(UHC) emissions without compromising engine performance at part loads is the current focus of dual fuel engine research.The present work focuses on an experimental investigation conducted on a dual fuel(diesel-natural gas) engine to examine the simultaneous effect of inlet air pre-heating and exhaust gas recirculation(EGR) ratio on performance and emission characteristics at part loads.The use of EGR at high levels seems to be unable to improve the engine performance at part loads.However,it is shown that EGR combined with pre-heating of inlet air can slightly increase thermal efficiency,resulting in reduced levels of both unburned hydrocarbon and NOx emissions.CO and UHC emissions are reduced by 24% and 31%,respectively,The NOx emissions decrease by 21% because of the lower combustion temperature due to the much inert gas brought by EGR and decreased oxygen concentration in the cylinder.

Gas Phase Thermodynamic Properties of Polychlorinated Xanthones Predicted with DFT Method and Cl Substituted Position

The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G**level.It is found that the chlorine substitution pattern strongly influences the thermodynamic properties of the compounds.The thermodynamic properties of congeners with the same number of chlorines also depend on the chlorine substitution pattern,especially for ortho-substituted congeners.PCXT congeners with one phenyl ring fully chlorinated are found to be the least stable among the analogues.The effect of the chlorine substitution pattern is quantitatively studied by considering the number and position of Cl atom substitution(NPCS).The results show that the NPCS model may be used to predict the thermodynamic properties for all 135 PCXT congeners. In addition,the values of molar heat capacities at constant pressure(cp,m)from 200 to 1000 K for PCXT congeners are calculated,and the temperature dependence relation of this parameter is obtained using the least-squares method.