丙烯酸急冷吸收塔工艺改造的研究

现行国内丙烯酸急冷吸收塔塔顶丙烯酸含量较高,产品损失较多,能耗较大;国外采用新工艺将急冷塔改为急冷加吸收的形式,在减少塔顶丙烯酸含量的同时降低了能耗。选择NIQUAC—HOC—HENRY组合模型对现行工艺流程和操作条件进行模拟,结果表明：物流模拟值和实测值吻合良好。将此模型应用到新工艺条件下,比较多个条件下的结果并进行分析,最终选择出最佳的工艺操作条件和塔设备结构参数。     

双极膜电渗析法由硫酸铵制备硫酸的工艺研究

利用两室双极膜电渗析法从硫酸铵溶液中制备硫酸。探讨了电渗析过程中的电流效率、能耗、产酸量等指标。实验结果表明,产酸量随时间的延长而增加,在恒定电流密度（0.09A.cm-2）的条件下,硫酸的电流效率达到90%,能耗为2.5～2.6kW.h.kg-1。     

Vacuum pressure swing adsorption process for coalbed methane enrichment

The enrichment of low concentration coalbed methane using adsorption process with activated carbon adsorbent was studied in this work.Adsorption isotherms of methane,nitrogen and carbon dioxide on activated carbon were measured by volumetric method,meanwhile a series of breakthrough tests with single component,binary components and three components feed mixture has been performed for exploring dynamic adsorption behaviors.Moreover,a rigorous mathematical model of adsorption bed containing mass,energy,and momentum conservation equation as well as dual-site Langmuir model with the Linear driving force model for gas-solid phase mass transfer has been proposed for numerical modeling and simulation of fixed bed breakthrough process and vacuum pressure swing adsorption process.Furthermore,the lumped mass transfer coefficient of methane,nitrogen and carbon dioxide on activated carbon adsorbent has been determined to be 0.3 s~(-1),1.0 s~(-1) and 0.06 s~(-1) by fitting the breakthrough curves using numerical calculation.Additionally,a six bed VPSA process with twelve step cycle sequence has been proposed and investigated for low concentration coalbed methane enrichment.Results demonstrated that the methane molar fraction in feed mixture ranged from 10% to 50% could be enriched to 32.15% to 88.75% methane in heavy product gas with a methane recovery higher than 83%under the adsorption pressure of 3 bar(1 bar=10~5 Pa) and desorption pressure of 0.1 bar.Energy consumption of this VPSA process was varied from 0.165 kW·h·m~(-3) CH_4 to 0.649 kW·h·m~(-3) CH_4.Finally,a dual-stage VPSA process has been successfully developed to upgrade a low concentration coalbed methane containing 20% methane to a target product gas with methane purity higher than 90%,meanwhile the total methane recovery was up to 98.71% with a total energy consumption of 0.504 kW·h·m~(-3) CH_4.     

复分解电渗析清洁生产谷氨酸钠新工艺

谷氨酸钠（sodium glutamate,NaGA）是味精（monosodium glutamate,MSG）的主要成分,其传统生产方法为"等电点结晶-酸碱中和"法,传统工艺存在工艺流程长、酸碱消耗大、环境污染严重等问题,而且其谷氨酸钠产品液浓度尚未达到结晶工艺所需的浓度。为此本文提出复分解电渗析离子重组工艺来清洁生产谷氨酸钠,并对该工艺进行了实验验证及过程优化。复分解电渗析可实现原料液的一步转化,直接获得高浓度谷氨酸钠产品液,在优化条件下,最终产品液浓度为1.79mol/L （约30.2%）,转化率为91.2%,能耗为2.98kW·h/kgNaGA,其副产（NH₄）₂SO₄可作为生产铵肥的原料,不存在二次污染。此工艺具有工艺流程短、酸碱零消耗、无二次污染的优点,而且所得谷氨酸钠产品液浓度达到了结晶工艺所需的浓度要求,这对电驱动膜过程在味精产业的应用具有重要意义。并通过对树脂填充床电渗析与普通电渗析、均相离子交换膜与异相离子交换膜的比较实验,验证了选用异相膜树脂填充床电渗析生产谷氨酸钠的合理性。     

氟硅酸中碘回收的还原吸收实验研究

将氟硅酸中的碘氧化后采用热空气吹出,再用含SO_2吸收液还原吸收热空气中的碘。考察还原吸收碘的工艺条件对碘吸收率的影响。实验得出碘的最佳吸收工艺条件为:每升含碘热空气SO_2用量为3.5~4.5 mL,吸收液pH 4~7,吸收液喷淋密度12 m~3/(m~2·h),温度30~40℃,吸收时间为8 min;最佳工艺条件下碘吸收率达到80%以上。     

微波辐射制备纤维素基Cu~(2+)吸附树脂

采用N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾/硫代硫酸钠为引发剂,通过微波辐射将丙烯酰胺(AM)和丙烯酸(AA)接枝到纤维素,制备了具有重金属吸附性能的树脂,并采用FTIR对产物结构进行了表征。结果表明,当纤维素含量为AA的10%,AM:AA=3:1,交联剂和引发剂用量分别为AA的1.0%和0.65%,AA中和度为70%时,在280 W微波功率辐射下,仅需要300 s即可制得对Cu~(2+)饱和吸附度为65 mg·g-1的重金属吸附树脂,且该工艺过程无须预处理和后处理,直接获得干燥的吸附树脂。     

电渗析分离乙二醛与硝酸的过程研究

在硝酸氧化乙醛制备乙二醛的过程中,需要除去产品中未反应的硝酸。常规的处理工艺容易引起硝酸再次发生氧化反应,因此需要探索新的脱酸技术。文中对电渗析法分离乙二醛溶液中的硝酸进行了实验研究,筛选了3种均相离子交换膜进行实验,使用筛选出的J-1-18离子交换膜组装电渗析装置进行分离过程的工艺条件研究。实验研究了膜堆电压对硝酸脱除率的影响和操作电压对电流效率的影响,考察了硝酸初始质量分数对电渗析分离的影响。研究结果表明:电渗析在低电压下操作,电流主要用于硝酸根离子的迁移,可实现硝酸的有效分离,且分离硝酸所用时间短,还有利于分别回收硝酸和乙酸。     

ZIF-8浆液法分离CH4/N2的双吸收-吸附塔工艺流程建模与模拟

由于ZIF-8浆液独特的可流动性，可以借鉴传统的吸收-解吸工艺，实现煤层气中甲烷的多级连续高效富集。在单吸收-吸附塔工艺的基础上，为了进一步降低能耗，提出了高低压双吸收-吸附塔新型分离工艺，并对该工艺进行了全流程建模及模拟。采用平衡级法，建立了工艺流程中各单元传质设备的数学模型，包括吸收-吸附塔、闪蒸罐、解吸塔。此外，还进行了灵敏度分析，探究了平衡级数、进料位置、气液比、解吸压力等因素对产品气中甲烷浓度以及回收率等工艺性能的影响。模拟结果表明，当产品气中甲烷浓度达到90.13%（mol）时，回收率为90.25%。并且单位原料气能耗为0.445 kW·h∙m^-3（原料气），低于单塔能耗（0.510 kW·h∙m^-3）。由此，改进的双塔工艺在满足甲烷纯度和回收率的同时，相较于单塔工艺进一步降低了能耗。     

丙烯酸工艺技术路线分析以及直氧法探究

丙烯酸广泛用于化工行业酯类聚合单体等原料.丙烯酸作为乙烯类单体在聚合反应中聚合速率较快,它的生产工艺方法很多,主要采用甘油等原料,生产工艺方法主要有丙烷脱氢氧化以及丙烯直接氧化两种工艺方法.本文通过对比不同的生产工艺路线,依据丙烯酸生产的现状、各主要企业的产能、装置运行情况,提出了直氧法生产丙烯酸的工艺现状以及改进,提...     

Lactic acid recovery from fermentation broth using one‐stage electrodialysis

One‐stage electrodialysis (ED) for lactic acid recovery with two‐ and three‐compartment water‐splitting ED (WSED) was investigated using various ion‐exchange membranes in order to overcome the inefficiency of two‐stage ED, which consists of desalting ED for recovery and partial purification and subsequent WSED for acidification. The two‐compartment WSED had a low current efficiency and high energy consumption in spite of a simple stack configuration. A three‐compartment WSED successfully converted sodium lactate in the fermentation broth into lactic acid and sodium hydroxide with average yields of 96% and 93%, respectively. In relation to lactic acid purification, of the membranes tested in this study, the highest glucose rejection, 98.3%, was achieved using a PC 100D membrane. The CMS membrane rejected magnesium and calcium at levels as high as 81.7% and 78.5%, respectively. We concluded that the three‐compartment WSED with properly chosen membranes, enabled lactic acid to be recovered directly from the fermentation broth. © 2001 Society of Chemical Industry     

Transport hindrances with electrodialytic recovery of citric acid from solution of strong electrolytes

Electrodialytic(ED) recovery of citric acid(CA) in the presence/absence of strong electrolytes(NaCl, CaCl_2 and FeCl_3) was separately analyzed under different process conditions. Recovery effectiveness was quantitatively estimated from current efficiency values. Efficiency attained optimum value with both flow rate and potential applied, while a monotonic rise was noted with temperature which got lowered beyond 0.1 mol·L~(-1) feed concentration. 40% drop in efficiency was recorded in the presence of strong electrolytes(NaCl, CaCl_2 and FeCl3) in feed relative to their presence in concentrate. Severe transport hindrance and efficiency loss were attributed to adsorption and allied physicochemical changes occurred with anion/cation exchange membranes(AEM/CEM) and these were confirmed through contact angle/Chronopotentiometry/AFM/EDX. Sluggish potential rise(Galvanostatic mode) in Chronopotentiometric analysis indicated diffusion limiting transport of organic acids influenced AEM resistance. XRD and EDX analysis indicated the presence of salt hydrates/ions(Ca~(2+)/Fe~(3+)) over CEM justifying the resistance buildup due to adsorption of multivalent metal ion(s) and salts.     

添加剂对单膜双室同槽电解膜电积工艺的影响

采用单膜双室膜电积工艺在MnSO₄+(NH₄)₂SO₄电解液体系中电沉积金属锰,同时阳极联产电解二氧化锰并富集回收硫酸,研究了两种典型无机、有机复合添加剂亚硒酸、聚丙烯酰胺+硫脲对膜电积工艺效果的影响。结果表明,单膜双室同槽电解工艺中添加剂的使用对产锰率、酸回收率以及能耗等都有较大改善。无机添加剂亚硒酸的最适浓度在0.3g/L时,其产锰率可达84.9%,酸回收率为79.5%,能耗为5545kW·h/t;有机复合添加剂聚丙烯酰胺浓度为0.01g/L、硫脲浓度为0.02g/L时,其产锰率可达75.1%,酸回收率为76.5%,能耗为6034kW·h/t,此时电沉积锰表面白皙光亮、均匀细致,其形貌、质量都有很大的改观。     

EDI用于处理含甲酸废水

在工业生产过程中,排放的废水里含有大量的甲酸。本文以含甲酸废水处理为研究对象,采用自主设计的一级一段电去离子膜堆装置,通过考察I-U、pH-U等特征曲线,研究了离子交换膜、离子交换树脂及树脂填充比例、流速等操作条件对膜堆性能的影响。结果表明：采用异相膜和凝胶型树脂、淡室填充100%阴树脂、淡水流速为2.5 L/h的操作条件,可使EDI膜堆效果最佳;不同甲酸浓度对能耗的影响比较小,淡室浓度变化情况基本相同;当淡室甲酸质量分数为1.00%时,EDI膜堆可获得较高的电流并具有较低的耗电量。总结认为该研究结果可为EDI处理甲酸废水工业装置提供设计依据。     

Asymmetric bipolar membrane electrodialysis for acid and base production

Bipolar membrane electrodialysis (BMED) is a promising technique for upgrading traditional manufacturing procedures and achieving a circular economy. However, the industrial applications of BMED technology have been restricted by the large consumption of expensive bipolar membranes and the unmatching behavior between water splitting and ion migration. Herein, we proposed a novel asymmetric bipolar membrane electrodialysis (ABMED) to regulate the water splitting in the bipolar membrane and orientational ion migration in the electrodialysis (ED). It was found that the ABMED exhibited comparable performances to BMED for acid/base production when the area of the bipolar membrane was reduced to 50% of the monopolar membrane. The total process cost of ABMED was 0.78 $/kg NaOH, which is 21% lower than the BMED process. The asymmetric membrane design was capable to boost the water splitting in the bipolar membrane and to eliminate the concentration polarization in the ED process.     

Recovery of chlorine from dilute hydrochloric acid by electrolysis using a chlorine resistant anion exchange membrane

A new chlorine resistant anion exchange membrane enables innovative possibilities for hydrochloric acid electrolysis for recovery of chlorine. This is of interest for hydrochloric acid that is neutralized in the chemical industry because purity and concentration are not sufficiently high for recycling. In the common electrolysis process hydrochloric acid is fed into the anode compartment and needs a satisfactory HCl concentration for supplying the anode with chloride ions. Using an anion exchange membrane as a cell separator the feed flows into the cathode chamber where a low HCl concentration is acceptable because Cl⁻ ions at the anode can be supplied by addition of a salt which is not consumed. Experimental data of the membrane and the process are presented: membrane permselectivity improved up to above 97% using CaCl₂ as added salt, chlorine current efficiency up to 98% and oxygen content as low as 0.5 vol%, cell voltage at 4 kA m⁻² 2.3 V, equivalent to 1740 kWh per t produced chlorine, even at low HCl concentrations. Thus, the power consumption is comparable with the common process. A problem of the new process is the high water transport through the membrane. Therefore, experiments for two process alternatives were carried out. Disadvantages of water transport can be avoided by using a high concentrated CaCl₂ solution as anolyte and catholyte and as absorption medium for diluted HCl gas streams. Additionally, a cell design was investigated where the anode is directly connected to the membrane in an empty (gas filled) anode compartment.     

Determination of the degradation apparent activation energy of acrylonitrile/acrylic acid copolymers

Acrylonitrile/acrylic acid copolymers were prepared by H₂O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry was used to investigate the degradation of acrylonitrile/acrylic acid copolymers in air. The apparent activation energy of degradation of the copolymer was calculated with the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. It has been found that increasing the dimethyl formamide concentration in the solvent mixture led to a gradual increase (97.3–149.4 kJ mol^?1) in the apparent activation energy of degradation of the acrylonitrile/acrylic acid copolymers. The apparent activation energy decreases with increase in acrylic acid concentration, and this change became less prominent as the acrylic acid/acrylonitrile weight ratio is more than 5/95. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4668–4671, 2006     

Chemical looping gasification of maceral from low-rank coal:Products distribution and kinetic analysis on vitrinite

The product distribution and kinetic analysis of low-rank coal vitrinite were investigated during the chemical looping gasification (CLG) process.The acid washing method was used to treat low-rank coal,and the density gradient centrifugation method was adopted to obtain the coal macerals.By combining thermogravimetric analysis and online mass spectrometry,the influence of the heating rate and oxygen carrier (Fe2O3) blending ratio on product distribution was discussed.The macroscopic kinetic parameters were solved by the Kissinger-Akahira-Sunose (KAS) method,and the main gaseous product formation kinetic parameters were solved by the iso-conversion method.The results of vitrinite during slow heating chemical looping gasification showed that the main weight loss interval was 400-600 ℃,and the solid yield of sample vitrinite-Fe-10 at different heating rates was 64.30％-69.67％.When β =20 ℃·min-1,the maximum decomposition rate of vitrinite-Fe-10 was-0.312％·min-1.The addition of Fe2O3 reduced the maximum decomposition rate,but by comparing the chemical looping conversion characteristic index,it could be inferred that the chemical looping gasification of vitrinite might produce volatile sub-stances higher than the pyrolysis process of vitrinite alone.The average activation energy of the reaction was significantly reduced during chemical looping gasification of vitrinite,which was lower than the average activation energy of 448.69 kJ·mol-1 during the pyrolysis process of vitrinite alone.The gaseous products were mainly CO and CO2.When the heating rate was 10 ℃·min-1,the highest activation energy for CH4 formation was 21.353 kJ·mol-1,and the lowest activation energy for CO formation was 9.7333 kJ·mol-1.This study provides basic data for exploring coal chemical looping gasification mecha-nism and reactor design by studying the chemical looping gasification process of coal macerals.     

己二酸对MEA吸收-解吸CO2过程的影响<

实验研究了己二酸对MEA水溶液吸收-解吸CO₂的影响。在0.4 mol·L-1 MEA的CO₂吸收富液解吸过程加入一定量的己二酸并分析了其对CO₂解吸能耗和解吸速率的影响,发现解吸速率明显升高,析出单位体积CO₂的能耗显著降低;对解吸还原后的贫液进行了CO₂二次吸收的实验,发现因加酸引起的CO₂二次吸收量变化小于7%;为去除不确定因素对CO₂相似文献   

甲基氯硅烷精馏流程的模拟与优化

采用Aspen plus软件对工业七塔精馏过程进行全流程建模与模拟,优化工艺参数,研究了新的精馏节能工艺。对一甲塔等7个精馏塔采用双因素水平的灵敏度分析,考察了塔釜采出率、回流比、进料位置和塔顶压力对产品浓度和热负荷的影响,确定一甲塔最优的工艺参数：塔釜摩尔采出率为0.92,摩尔回流比为130,塔顶压力为0.18 MPa,总理论板数为400,在210块理论板位置进料。在此基础上,针对高能耗的脱高塔/脱低塔,模拟研究了双效精馏新工艺,新工艺可节省39.70%的年总成本;针对一甲塔模拟研究了热泵精馏新工艺,新工艺可降低41.42%的年总成本。     

Electrodialysis of acid effluents containing metallic divalent salts: recovery of acid with a cation-exchange membrane modified in situ

The recovery of sulfuric acid from effluents containing metallic salts (Mg, Zn, Mn) was achieved by electrodialysis with a Nafion® cation exchange membrane modified in situ by electrodeposition of polyethyleneimine on one side of the membrane. The purity of the acid obtained depends on the experimental conditions of this electrodeposition. The total metal leakage through the modified membrane can be lowered to 0.5% with no significant increase in the energy consumption of the process due to a possible increase of the electrical resistance. These results are comparable with, and even better than, those obtained with commercial membranes specially designed for this type of application. The advantage of this modification process is the possibility of regenerating the surface layer directly in the membrane stack.