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  • Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

    The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates.Biological occurrence of simultaneous nitrification and denitrifieation was verified in the aspect of nitrogen mass balance and alkalinity.The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate.In each experimental run the floe sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc....

    2020-11-22 17:58:37浏览:28 biologicalnitrogenremovaldissolvedoxygenfloesizesimultaneous

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  • Advanced sludge reduction and phosphorous removal process

    An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ(COD) is 332 - 420 mg/L, concentration of ammonia ρ(NH3-N) is 30 - 40 mg/L and concentration of total phosphorous ρ(TP) is 6.0 - 9.0 mg/L in influent, the system still ensures ρ(COD)<23 mg/L, ρ(NH3-N)<3.2 mg/L and ρ(TP)<0.72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ(DO) is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91%. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification....

    2020-11-10 09:33:08浏览:23 sludgereductionphosphorousremovaldissolvedoxygensimultaneousnitrification

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  • 浮法玻璃生产线循环水系统的腐蚀与防治

    在浮法玻璃生产中,循环水在熔窑搅拌器、锡槽拉边机冷却水套等设备和仪表中是必不可少的,循环冷却水系统是保证浮法玻璃企业熔窑、锡槽、退火窑三大热工设备正常运行的重要设备,研究循环水系统的腐蚀并处理好腐蚀问题对保证生产运行意义重大。...

    2020-11-10 09:33:08浏览:27 循环水系统氧腐蚀防治措施circulatingwatersystemoxygencorrosioncontrolmeasures

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  • 合成气氧分析的作用及介质的操作条件

    介绍了壳牌煤气化工艺中与合成气氧含量分析16QIS0014有关的工艺过程;阐明了合成气氧含量分析的作用;确定了被测介质的操作条件;提出了合成气氧分析的设计优化建议。...

    2020-09-30 09:14:00浏览:23 壳牌煤气化氧分析分析仪(16QIS0014)操作条件顺控(顺序控制)点火烧嘴开工烧嘴Shellcoalgasificationoxygen

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  • 生活污水低碳减排的研究

    为倡导低碳生活方式,减少污染物的排放,本文进行了生活污水低碳减排的研究。测试了日常生活中经常废弃的液体食品、调味品、洗涤用品和淘米水的COD数值,结果表明:测试的生活中废弃液体的COD值非常高,食用油最高为2282210mg/L,淘米水最低为13595mg/L,远高于一般生活污水的COD数值。通过理论分析,对上述物质的COD值进行了计算,发现测试值和计算值大体相近,相对偏差小于8%,说明测试结果是可信的。分析COD数值较高的原因,是这些物质中含有较多的含碳有机物。通过减排数据说明,低碳生活应该从每个人做起,要做好日常生活中的COD减排工作。...

    2020-09-25 09:10:57浏览:27 化学需氧量(COD)生活污水废弃生活液体减排低碳chemicaloxygendemand(COD)municipalwastewater

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  • The Mechanism and Influencing Factors of Corrosion in a Gas Heating-Furnace

    Natural gas should be heated and throttled for the purpose of purification and transportation at the first gas production factory of the Changqing field. The safe use and heat-transfer efficiency of a heating-furnace affect the safe and smooth production of natural gas directly. At gas collecting stations now, no measures of anticorrosion have been adopted in heating furnaces which erode and scale badly.In order to solve the corrosive problem of heating-furnaces, prolong operating life of heating-furnaces,assure safe and smooth production of natural gas, the mechanism and influencing factors of corrosion of the heating-furnace were analyzed and some corresponding measures were brought forward based on a field investigation of usage behavior and present operational status of heating-furnaces at the first gas production factory. The results show that the corrosive ion and soluble CO2 and O2 in water erode metal badly at the condition of being heated. Corrosion of a heating-furnace are mostly oxygen corrosion, corrosive ion corrosion, acid corrosion, iron encrustation corrosion, dry and wet interface corrosion, caustic corrosion, etc; The influencing factors of corrosion mainly include soluble O2 and CO2 in water, pH value, heat loading, corrosive ion, soluble solid (salinity) and non-flowing character of water, etc....

    2020-09-15 12:28:59浏览:29 heating-furnacecorrosionmechanisminfluencingfactoroxygen

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  • 炭化杨木单板制备胶合板的氧指数和热重分析

    通过研究不同炭化处理温度下的杨木单板制备胶合板的氧指数和热重分析,以评价其阻燃性能.分别将160,180和200℃炭化处理后的单板热压制成5层对称结构胶合板,氧指数和热重分析结果表明:炭化处理后的胶合板氧指数均高于未处理的胶合板,当炭化条件为200℃和2h时,胶合板氧指数最大值为30.3%,达到B1级难燃材料标准.由TG-DTG曲线可知,炭化处理前后胶合板的TG、DTG曲线变化趋势完全一致,主要差异体现在最终的成炭率、肩峰及特征峰对应的具体温度上.炭化条件为200℃和2h时的最终成炭率为21.04%,达到最大值;肩峰对应温度随炭化温度的升高而降低,炭化处理后胶合板特征峰对应温度均小于未处理的胶合板....

    2020-09-02 20:01:33浏览:37 杨木炭化处理氧指数热重分析胶合板poplarcarbonizationtreatmentoxygenindex

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  • 浅析影响GE气化炉气体成分波动的原因

    根据笔者自己对GE气化炉的操作经验进行了总结,并对GE气化炉在运行过程中的出现的一些问题从以下可能影响GE气化炉运行的几个方面进行了初步的分析,根据GE气化炉在运行过程出现的问题和现象可能对影响GE气化炉气体成分波动的原因进行了分析,并提出了解决问题的建议。...

    2020-07-12 21:36:56浏览:27 气体成分波动煤质水煤浆氧纯度gascompositionfluctuationcoalpropertyslurryoxygenpurity

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  • GSP气化炉氧气流量的测量

    通过对某煤气化装置的GSP气化炉氧气流量测量方法的探讨,介绍采用平衡孔板计和双差压变送器分段测量氧气流量的测量方案、使用效果和改进措施....

    2020-07-12 21:36:56浏览:26 氧气流量测量平衡孔板流量计双差压变速器分段测量oxygenflowmeasurementbalancedplateorificemeter

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  • Novel methanol-tolerant Ir-S/C chalcogenide electrocatalysts for oxygen reduction in DMFC fuel cell

    Novel methanol-tolerant oxygen-reduction catalysts, iridium-sulphur (Ir-S) chalcogenides with differ ent Ir/S atomic ratios, were synthesized via a precipitation method using H21rCI6 and Na2SO3 as the Ir and S precursors. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the IrxSl-x/C chalcogenide catalysts. Particle size ranging from 2.5 to 2.8 nm though obvious agglomeration was found on carbon support. However, these chalcogenide catalysts showed strong catalytic activity towards the oxygen reduction reaction (ORR) and high methanol tolerance, strongly suggesting these novel catalysts as promising candidates for direct methanol fuel cell (DMFC) cathode applications....

    2020-07-08 21:52:19浏览:25 DMFCIridiumsulphurCathodiccatalystoxygenreductionmethanoltolerant

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  • Methanol Tolerant FeTPP-Pt/C Co-catalysts for the Electroreduction of Oxygen

    It was found for the first time that iron tetraphenylporphyrin (FeTPP)-Pt/C showed the good activity for the electroreduction of oxygen and methanol tolerant ability. Their perfor- mances were related to the heat-treatment temperature....

    2020-07-08 21:52:19浏览:25 FeTPPPtoxygenreductionmethanoltolerant

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  • Catalytic Preparation of Methyl Formate from Methanol over Silver

    A catalytic reaction over a silver catalyst performed in an unregarded temperature region(473-873 K) with a long catalytic lifetime for the production of methyl formate from methanol was provided as a potential preparing route. The optimal yield of methyl formate(ca. 14.8%) with a selectivity >90% was obtained at about 573 K. Because α-oxygen species and bulk oxygen species coexist in the unregarded temperature region, a synergistic process concerning α-oxygen species and bulk oxygen species was proved over Oα -rich and Oγ-rich samples....

    2020-07-08 21:52:19浏览:16 SilvermethanolmethylformateoxygenspeciesSynergisticeffect

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  • THE EFFECT OF POWERFUL OXYGEN EVOLUTION METAL-OXIDE ON THE ELECTROOXIDATION OF METHANOL

    An improved thermal decomposition method is used to prepare modified titanium base anode. Some researches have been carried out to learn about the oxygen evolution properties of RuMn, RuCo, RuCe and RuEu etc. in H2SO4 solution and their effect on the electrooxidation of methanol if added into the catalytic layers of Pt/Ti electrodes. The result indicates that the Pt/Ti electrodes containing RuMn, RuCo and RuEu etc. metal oxide catalysts with the powerful evolution property exhibit a higher electro-catalytic activity towards methanol electrooxidation than Pt/Ti electrodes without composite metal oxide catalysts....

    2020-07-08 21:52:19浏览:20 directmethanolfuelcellmetaloxidecoatingoxygenevolutionactivity

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  • Methanol Tolerant PWA-Pt/C Catalyst with Excellent Electrocatalytic Activity for Oxygen Reduction in

    It was reported for the first time that phosphorictungstenic acid (PWA) could promote the oxygen reduction reaction (ORR) and inhibit the methanol oxidation reaction at the cathodic Pt/C catalyst in the direct methanol fuel cell (DMFC). When the weight ratio of PWA to Pt/C is 1,the composite catalyst increases the reduction current of oxygen by about 38% and decreases the oxidation current of methanol by about 76% compared with that of the Pt/C catalyst....

    2020-07-08 21:52:19浏览:28 DMFCphosphorictungstenicacidmethanoltoleranceoxygenreduction

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  • Removal of PCDD/Fs and PCBs from sediment by oxygen free pyrolysis

    Few studies have dealt on the evaluation of volatilization and decomposition reactions ofdioxins from sediment by oxygen free pyrolysis. In this study, the performance of pyrolysis on the removal of dioxins from sediment was investigated. Dioxin concentrations of the raw sediment and the solid residues after pyrolysis were analyzed at different conditions. Results showed a removal efficiency of 99.9999% for total dioxins at 800℃ and retention time of 30 min. All the polychlorinated dibenzo-furans (PCDFs) have been removed and were not formed in the solid residues at the retention time range of 30-90 min at 800℃. Close to 100% removal of polychlorinated dibenzo-p-dioxins (PCDDs) was also achieved. Only trace PCDDs were detected in the solid yields at a retention time of 60 min. The highest removal efficiency of polychlorinated biphenyls (PCBs) was more than 99.9994% at a retention time of 30 min. During cooling period following pyrolysis, however, the concentration of total dioxins in solid residues increased 130 times as compared to that of the raw sediment under air atmosphere. This confirmed that some complex reactions do occur to form PCDD/Fs and PCBs from 800 to 400℃ in the presence of oxygen. Oxygen-free atmosphere therefore can prevent formation of dioxin during thermal process thus generating clean solid residues....

    2020-07-08 21:52:19浏览:19 dioxinspyrolysisoxygenfreesedimentPCBs

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  • EVALUATION OF WATER AND SEDIMENT QUALITIES AT RIVER MOUTHS IN THE HAIHE RIVER SYSTEM

    Water and sediment qualities are studied by analyzing samples taking from the mouths of the Haihe, Duliujian, New Ziya and Beipai rivers in the Haihe river basin in north China in 2005 and 2001, in order to find the changes of water and sediment pollutions. The concentrations of heavy metals, arsenic, total nitrogen (TN) and total phosphorus (TP) are analyzed and results have been compared for the two times. The in-situ measurement for Dissolved Oxygen (DO) and Sediment Oxygen Demand (SOD) rates were carried at the Haihe and Duliujian river mouths in 2006. The results show that the waters of the 4 river mouths are still seriously polluted, though much improved in the case of the Haihe and Duliujian rivers. The main pollutants are TP and TN in the New Ziya and Beipai rivers and mercury (Hg) at all 4 river mouths. Compared with those in 2001, the concentrations of almost all metals and arsenic in the 4 river mouths have decreased. Water quality at Haihe and Duliujian shows an improving trend, while the water quality at Beipai is similar to that of 2001. In contrast, water at the New Ziya river mouth is more severely polluted. The sediments in the 4 river mouths are not seriously polluted by heavy metals but are polluted by nitrogen and phosphorus. Most of the pollutant contents in the sediments show little change between 2001 and 2005. The in-situ DO and SOD measurement shows that the waters at the Haihe river mouth is in the state of oxygen depletion, and SOD is important consumer of DO at the river mouths. The overall analysis shows that increasing water pollution and eutrophication in waters far from cities are ongoing causes of concern....

    2020-07-08 21:52:19浏览:10 rivermouthwaterqualitysedimentEutrophicationoxygendemand

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  • To Improve the Dispersibility of Carbon Black in Water with Plasma and Organic Amines Treatments

    Carbon black has been widely used in many industrial areas,but it is poor dispersibility in water. In order to improve its dispersibility in water,carbon black was treated by oxygen plasma. Plasma treatment,as one of the environmental friendly methods,has been used to introduce polar groups,mainly oxygen-containing groups,to the surface of carbon black. The results show the dispersibility of treated carbon black in water is greatly improved,which is expressed with the centrifugal and gravity settlement rates. Analysis of the treated carbon black with X-ray photoelectron spectroscopy (XPS) indicates that oxygen plasma treatment can cause significant increase of polar groups including C-OH,COOH,C=O,and O-C-O on the surface of carbon black thus greatly improves the dispersing stability of carbon black in water. Besides,the dispersibility of plasma treated carbon black can be further improved by the addition of organic amines,especially polyetheramines. The improvement of the dispersing stability of carbon black has also been confirmed by zeta potential measurements....

    2020-07-08 21:52:19浏览:33 carbonblackoxygenplasmaaminesX-rayphotoelectronspectroscopy

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  • Iron stability in drinking water distribution systems in a city of China

    A field study on the estimation and analysis of iron stability in drinking water distribution system was carried out in a city of China. The stability of iron ion was estimated by pC-pH figure. It was found that iron ion was unstable, with a high Fe (OH)3precipitation tendency and obvious increase in turbidity. The outer layer of the corrosion scale was compact, while the inner core was porous. The main composition of the scale was iron, and the possible compound constitutes of the outer scale were α-FeOOH,γ-FeOOH, α-Fe2O3, γ-Fe2O3, FeCl3, while the inner were Fe3O4, FeCl2, FeCO3. According to the characteristics of the corrosion scale, it was thought that the main reason for iron instability was iron release from corrosion scale. Many factors such as pipe materials,dissolved oxygen and chlorine residual affect iron release. Generally, higher iron release occurred with lower dissolved oxygen or chlorine residual concentration, while lower iron release occurred with higher dissolved oxygen or chlorine residual concentration.The reason was considered that the passivated out layer of scale of ferric oxide was broken down by reductive reaction in a condition of low oxidants concentration, which would result more rapid corrosion of the pipe and red water phenomenon....

    2020-07-08 08:49:41浏览:20 Chlorineresidualcorrosionscaledissolvedoxygendrinkingwaterdistribution

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  • Treatment of oil/water emulsion by polyethylene glycol ultrafiltration membrane

    Polyethylene glycol(PEG) membranes with different molecular mass cut-offs were used to treat oil/water emulsion, and the effects of experimental conditions including pressure, temperature and different opera-ting modes on permeate flux and removal rate of chemical oxygen demand (CODCr) were studied. The results show that the permeate flux of ultrafiltration membrane is influenced by pressure and temperature; practical pressure is chosen to be 0.3-0.7 MPa for the PEG with molecular mass cut-offs of 8 000 and 0.7-1.0 MPa for the PEG with molecular mass cut-offs of 2 500; and the practical temperature is chosen to be 25-32 ℃. Different operating modes of ultrafiltration also influence the permeate flux and removal rate of CODCr. The ultrafiltration membrane of intermittent cross-flow operating mode is easier to be influenced by blocky polarization and contamination than that of sequential cross-flow operating mode. Removal rate of CODCr in intermittent cross-flow and sequential cross-flow condition can be maintained at about 93%....

    2020-07-08 08:49:41浏览:25 wateremulsionultrafiltrationmembranepermeatefluxchemicaloxygen

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  • Experimental study on stable isotopic fractionation of evaporating water under varying temperature

    The variation of stable isotope ratios in natural waters provides valuable information that can be used to trace water movement. Evaporation plays a crucial role in determining the variation of stable isotopes. In this paper, several evaporation experiments were conducted in order to study the stable isotopic fractionation mechanism of water and analyze the influence of different temperatures on evaporation fractionation. Three group experiments of water evaporation under different temperatures and initial isotopic values were carried out. The results show that fractionation factors of hydrogen and oxygen may increase with temperature, and the average enrichment degree of hydrogen isotope D is 3.432 times that of oxygen isotope 18O. The results also show that the isotopic composition of the initial water has little influence on water evaporation fractionation, which is mainly affected by the state variables in the evaporation process, such as temperature. This research provides experimental data for further understanding the evaporation fractionation mechanism....

    2020-07-08 08:49:41浏览:20 waterevaporationhydrogenandoxygenisotopesfractionationmechanism

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  • Prediction of oxygen concentration and temperature distribution in loose coal based on B P neural ne

    An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal. In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles, it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion. For laboratory conditions, we de-signed our own experimental equipment composed of a control-heating system, a coal column and an oxygen concentration and temperature monitoring system, for simulation of spontaneous combustion of block coal (13-25 ram) covered with fine coal (0-3 mm). A BP artificial neural network (ANN) with 150 training samples was gradually established over the course of our experiment. Heating time, relative position of measuring points, the ratio of fine coal thickness, artificial density, voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables. Then our trained network was applied to predict the trend on the untried experimental data. The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal-6% by covering the coal pile with fine coal, which would meet the requirement to prevent spontaneous combustion of coal stockpiles. Based on the predic-tion of this ANN, the average errors of oxygen concentration and temperature were respectively 0.5% and 7 ~C, which meet actual tolerances. The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles....

    2020-06-12 16:19:45浏览:1394 loosecoalneuralnetworkSpontaneouscombustionofoxygenconcentration

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  • Extracting vanadium from stone-coal by oxygen pressure acid leaching and solvent extraction

    Vanadium extraction from stone-coal was investigated by oxygen pressure acid leaching and solvent extraction. The mineralogy of the stone-coal from Tongren City of Guizhou Province, China, was investigated by various determination methods. The effects of leaching time, leaching temperature, leaching agent concentration, leaching L/S ratio, granularity of material, additive consumption were investigated based on the mineralogy. The results show that under the conditions of leaching time of 3-4 h, temperature of 150 ℃, sulfuric acid consumption of 25%-30%, ratio of liquid to solid of 1.2:1, the granularity less than 0.074 mm, additive consumption of 3%-5%, and oxygen pressure of 1.2 MPa, and the vanadium leaching rate can be more than 92% by the method of two-step pressurized acid leaching. The powdery V2O5 product with 99.52% in V2O5 content is obtained by the flowsheet of acid recovery, removing iron by reduction process, solvent extraction, precipitating vanadium with ammonium water, and pyrolysis from the stone-coal oxygen pressure acid-leaching solution. The total recovery efficiency of vanadium is above 85%, which is more than 20% higher than that obtained in the conventional process. Furthermore, the new process does not cause air pollution since no HCl or Cl2 is released by calcination of the raw material....

    2020-06-12 16:19:10浏览:1395 stone-coalextractingvanadiumoxygenpressureacidLeachingrecovery

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  • Method of oxygen-enriched two-stage underground coal gasification

    Two-stage underground coal gasification was studied to improve the caloric value of the syngas and to extend gas production times. A model test using the oxygen-enriched two-stage coal gasification method was carried out. The composition of the gas produced, the time ratio of the two stages, and the role of the temperature field were analysed. The results show that oxygen-enriched two-stage gasification shortens the time of the first stage and prolongs the time of the second stage. Feed oxygen concentrations of 30%,35%, 40%, 45%, 60%, or 80% gave time ratios (first stage to second stage) of 1:0.12, 1:0.21, 1:0.51, 1:0.64,1:0.90, and 1:4.0 respectively. Cooling rates of the temperature field after steam injection decreased with time from about 19.1-27.4 ℃/min to 2.3-6.8 ℃/min. But this rate increased with increasing oxygen concentrations in the first stage. The caloric value of the syngas improves with increased oxygen concentration in the first stage. Injection of 80% oxygen-enriched air gave gas with the highest caloric value and also gave the longest production time. The caloric value of the gas obtained from the oxygenenriched two-stage gasification method lies in the range from 5.31 MJ/Nm3 to 10.54 MJ/Nm3....

    2020-06-12 16:17:33浏览:1395 undergroundcoalgasificationEnrichedoxygentwo-stagetemperature

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  • Oxidation kinetics regularity in spontaneous combustion of gas coal

    In order to investigate the oxidation kinetics of gas coal at low temperatures, we derived a rate equation of oxygen consumption during low-temperature oxidation of gas coal and deduced an E-c equation, expressing the relation between active energy E and oxygen concentration c. The reaction order n and active energy E were calculated with this equation based on experiments of static oxygen consumption tests. In addition, we proved the rationality of the E-c equation using a kinetic compensation effect and obtained the isokinetic temperature Tc. The results show that: 1) the gas coal oxidizes easily with increasing temperature and the oxidation tends to be spontaneous at higher temperatures; 2) the oxygen concentration c affects oxygen consumption very much at lower temperatures but has only a small effect at higher temperatures; 3) the isokinetic temperature Tc was 127 ℃ which has been experimentally validated as the key turning point during low-temperature spontaneous combustion of gas coal....

    2020-06-12 16:16:32浏览:1393 staticoxygenconsumptiontestsystemreactionorderactiveenergykinetic

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  • 氧气对低温甲醇洗系统的影响及解决措施

    分析了低温甲醇洗系统中氧气的来源;简述了氧气对低温甲醇洗系统的影响;提出了降低低温甲醇洗系统中氧气含量的控制措施以及相应的设计方案。...

    2020-06-12 15:49:26浏览:1395 低温甲醇洗氧气控制设计方案Rectisoloxygengascontroldesignscheme

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