茂名炼油厂脱硫胺液系统的整治

介绍了茂名石化炼油胺液系统存在热稳盐浓度高和胺液损耗大等问题,分析了胺液热稳盐的成因及造成胺液损耗大的原因,通过新增设胺液净化设备、脱硫塔和旋分器等技术改造,以及强化管理等,胺液系统热稳盐质量分数从5．84％降低至目前2．24％,效果显著。     

变质胺液净化复活技术进展

用于脱硫及脱碳的胺液在长期使用中因降解或杂质混入发生变质,导致脱硫脱碳效率下降、胺液发泡、装置腐蚀及能耗增大等系列问题,而胺液净化复活技术是解决胺液系统问题的有效手段。本文从变质胺液中污染物出发,分别总结了固体颗粒物、烃类及表面活性物质、胺变质产物及热稳定盐的成因、危害及其控制手段。针对热稳定盐等重点难处理污染物,主要介绍了蒸馏回收、离子交换以及电渗析等净化技术的技术原理及国内外研究与应用概况,并对技术特点进行总结分析。最后通过技术对比指出,电渗析因具备胺液回收率高、热稳定盐净化深度高、能耗适中、产生少量易处理污染物等特点,是我国在胺液净化复活技术领域最具潜力的发展方向。     

Comparing the compatibility of various functionalized polypropylenes with thermoplastic polyurethane (TPU)

Three functionalized polypropylenes (PP), a maleated PP (PP-g-MA), primary amine functionalized PP (PP-g-NH₂), and secondary amine functionalized PP (PP-g-NHR), were melt blended with a thermoplastic polyurethane (TPU) at different compositions. Compatibility of each functionalized PP with TPU was compared by investigating the binary blends using rheological (mixer torques, dynamic shear rheometry), thermal (dynamic mechanical analysis), mechanical (tensile test), and morphological (scanning electron microscopy with image analysis, particle size analysis) measurements. Compatibility of the three functionalized PP's with TPU is ranked in a decreasing order as follows: PP-g-NHR≥PP-g-NH₂?PP-g-MA, which is attributed to higher reactivity of amine (primary and secondary) with urethane linkages. Accordingly, the TPU blends with the two types of amine functionalized PP's exhibited much better synergy, as reflected by much improved mechanical properties including higher tensile strength and ultimate elongation, and finer and more stable morphologies.     

Integration of a chemical process model in a power plant modelling tool for the simulation of an amine based CO2 scrubber

Post-combustion is considered among the different options for CO₂ capture as the most mature available technology. All major components of the CO₂ absorption/desorption process are commercially available but at a smaller scale, and they are not integrated and optimized for the application in power plants. Therefore, it is still to be demonstrated that this process is a viable option for the capture of CO₂ at power plants. The amine scrubbing process with standard solvents is highly energy demanding due to solvent regeneration and CO₂ compression. This is a significant energy sink for the power plant and efficiency can be reduced up to 16%-points. In order to minimise the energy penalty, complete integration and optimization of the capture and the power plant processes are necessary.Simulations of the power plant cycle and the amine scrubbing system have been performed with specialized software. The results of the integration are discussed.     

Treatment performance of metal membrane microfiltration and electrodialysis integrated system for wastewater reclamation

The integrated system with microfiltration/electrodialysis was proposed for wastewater reclamation. The filterability of metal membrane, membrane fouling reduction by ozonated water and the effect of operational parameters were experimentally investigated. Backwashing by ozonated water showed stable and effective membrane fouling reduction. The removal ratio of nutrients such as NH₄⁺-N and PO₄³⁻-P concentration was about 96 and 94%, respectively, within 30 min of operation in the system. Proposed system showed good rejections on bacteria, suspended solids as well as ionic nutrients. Suggested wastewater reclamation system showed stable water quality during operational period over 6 months. Therefore, it is expected to be an effective and useful system for the reclamation of wastewater.     

Amine Solutions for Biogas Upgrading: Ideal versus Non‐Ideal Absorption Isotherms

Amine solutions were applied in carbon dioxide removal from a model mixture of biogas, carried out in a loop reactor system. In addition, the effect of CO₂ absorption acceleration in the presence of piperazine was confirmed and quantified, relating the obtained CO₂ loading with the piperazine concentration. Further, the interactions of CO₂ and water in aqueous amine solutions were discussed. The obtained acid gas loadings were accurately described taking into account the effect of the dissolved CO₂ on the equilibrium constant. A logarithmic absorption isotherm that follows from such considerations and a saturation‐type isotherm were compared. In describing the experimental data, advantages and disadvantages of both approaches are discussed.     

Influence of metal salts in reaction medium on performance enhancement of novel aliphatic–aromatic-based polyamide thin-film composite osmosis membranes

In this study, we report an easy and novel way to develop high flux aliphatic–aromatic-based thin-film composite (TFC) polyamide osmosis membranes by addition of inorganic metal salts with amine reactants in the reaction system of polyethylene imine (PEI) and 1,3-benzene dicarbonyl chloride. Inorganic metal salts like CuSO₄, NiSO₄, MgSO₄, and Al₂(SO₄)₃ added to block some of the amine groups of PEI through complexation which in turn changes the polycondensation reaction kinetics of amine acid chloride reaction. The prepared membranes were characterized using water contact angle and atomic force microscopy studies and the performances were evaluated both in reverse osmosis and forward osmosis mode. In presence of metal salts in reaction interface, the performance of TFC membranes was greatly enhanced and the optimum metal salt concentration was identified for individual metal salts for maximum performance enhancement. The effects of different anions for same metal ion and different molecular weight of PEI were evaluated on composite polyamide membrane performances. Water permeability (flux) of 63.48 L m^?2 h^?1 was achieved upon inorganic salt addition compared to the unmodified TFC membranes with flux of 42.1 L m^?2 h^?1 at similar salt rejection of ~95%. Based on the new findings, a conceptual model was proposed to explain the role of metal ion in amine solution on the resulting characteristics of aromatic–aliphatic type polyamide–polysulfone composite membrane.     

CO2 capture by adsorption with nitrogen enriched carbons

The success of CO₂ capture with solid sorbents is dependent on the development of a low cost sorbent with high CO₂ selectivity and adsorption capacity. Immobilised amines are expected to offer the benefits of liquid amines in the typical absorption process, with the added advantages that solids are easy to handle and that they do not give rise to corrosion problems. In this work, different alkylamines were evaluated as a potential source of basic sites for CO₂ capture, and a commercial activated carbon was used as a preliminary support in order to study the effect of the impregnation. The amine coating increased the basicity and nitrogen content of the carbon. However, it drastically reduced the microporous volume of the activated carbon, which is chiefly responsible for CO₂ physisorption, thus decreasing the capacity of raw carbon at room temperature.     

Experimental study on membrane wetting in gas–liquid membrane contacting process for CO2 absorption by single and mixed absorbents

The membrane wetting by the liquid absorbents is an important problem in the operation of gas–liquid membrane contacting process. In order to gain a better understanding on the role of absorbents on membrane wetting, monoethanolamine (MEA, primary amine), diethanolamine (DEA, secondary amine), and 2-amino-2-methyl-1-propanol (AMP, sterically hindred amine) were applied as absorbent solutions. The membrane used for the experiments was the hollow fiber polyvinylidenefluoride (PVDF) membrane. The performance of both single and mixed amine solutions on the CO₂ absorption capacity and membrane wetting potential were investigated. In addition, sodium chloride (NaCl, inorganic salt) and sodium glycinate (SG, organic salt) were added into the MEA aqueous solution to observe CO₂ flux and membrane wetting.The results revealed that the use of MEA solution and SG as absorbents gave highest CO₂ flux. The overall mass transfer coefficients obtained from the experiments also showed the same trend as CO₂ flux, i.e, the values were in the following order: MEA> AMP > DEA. However, the long-term flux was monitored and it was found that MEA also gave lowest flux decline due to the membrane wetting. The use of mixed amine solutions and the addition of NaCl did not help protect the membrane wetting. On the contrary, the addition of SG in to MEA solution can improve flux and resulted in stable CO₂ flux indicating that the membrane wetting was negligible.     

Absorption of Carbon Dioxide from Flue Gas using Blended Amine Solutions

Employing systematic experiments and comparing the CO₂ absorption amount, absorption rate and CO₂ loading of various amines and their mixtures, the optimal formula of blended amine solution is investigated. The results demonstrate the absorption characteristics of diethylenetriamine are the best, followed by monoethanolamine and methyldiethanolamine, while diethanolamine has no competitive advantage, neither in terms of the absorption amount and rate nor loading of CO₂. The amine concentration has a significant influence on CO₂ absorption, followed by formula and ratio, while the temperature and pressure affect little. The optimal formula of blended amine solution with the highest rate constant and activation energy of CO₂ absorption was determined.     

Carbon dioxide absorption into biphasic amine solvent with solvent loss reduction

The main challenge in the CO₂ capture from flue gases is to reduce the energy consumption required for solvent regeneration. Lipophilic amines exhibit a thermomorphic phase transition upon heating, giving rise to autoextractive behaviour, which enhances desorption at temperatures well below the solvent boiling point. The low regeneration temperature of less than 80 °C together with the high cyclic CO₂ loading capacity (c. 0.9 mol-CO₂/mol-absorbent) of such biphasic amine systems permit the use of low temperature and even waste heat for desorption purposes. In order to improve the capture process and reduce the commensurate energy demand still further, desorption experiments were carried out at 70-80 °C and techniques for enhancing CO₂ release without gas stripping were also studied. The comparison of various amines at a concentration of 3 M and for a 15 mol% CO₂ feed gas demonstrates the considerable potential of lipophilic amines for the CO₂ absorption process. Chemical stability is a decisive factor for the industrial application of amine absorbents. Degradation of the novel lipophilic amine absorbents was shown to be minor, while volatility losses represent a major shortcoming of the biphasic solvent systems. Appropriate countermeasures to limit solvent losses were examined experimentally.     

Kinetics study of carbon dioxide absorption in aqueous solutions of 1,6-hexamethyldiamine (HMDA) and 1,6-hexamethyldiamine, N,N′ di-methyl (HMDA, N,N′)

A study towards the kinetics of CO₂ in aqueous solutions of 1,6-hexamethyl diamine (HMDA) and 1,6-hexamethyl diamine, N,N′ di-methyl (HMDA, N,N′) was performed at concentrations ranging from 0.5 to 2.5 mol/L and temperatures from 283 up to 303 K. The kinetics data were determined by CO₂ absorption experiments using a stirred cell reactor with a flat interface between gas and liquid. These new CO₂ solvents were identified in earlier work for their high CO₂ capacity and limited corrosiveness. The experimental technique was validated using kinetic experiments for a 2.5 mol/L monoethanolamine solution. In view of double amine functionality and the six carbon chain between the amine groups, attention was paid to whether the amine groups acted independently and whether or not internal cyclisation would affect the carbamate forming mechanism. The reaction order with respect to HMDA was found to vary from 1.4 to 1.8 with increasing temperature. Absorption experiments in an equimolar solution of HMDA with HCl showed that the two amine groups react independently from each other towards CO₂. The reactivity of both diamines was more than five times larger than for monoethanolamine. The secondary diamine HMDA, N,N′ was found to be even more reactive towards CO₂. Additionally, the effect of CO₂ loading on the kinetics was studied for 0.5 mol/L aqueous solutions of HMDA and HMDA, N,N′ at 293 K. Both solvents are from absorption kinetics point of view good candidates for further evaluation as solvent (-component) for CO₂ capture.     

Solvent‐free diazotization–azidation of aryl amine using a polymer‐supported azide ion

Crosslinked poly (4‐vinylpyridine)‐supported azide ion was used as an effective azidating agent for deazodination of stable arenediazonium salts under solvent‐free conditions in high yields. The diazotization of aromatic amines was prepared by grinding the combination of an aromatic amine, sodium nitrite (NaNO₂), p‐toluene sulfonic acid (p‐TsOH), and 0.2 mL H₂O in a mortar. Grinding was continued for deazodination–azidation of the obtained relatively stable diazonium salts, with addition of crosslinked poly (4‐vinylpyridine) supported azide ion to obtain the corresponding aryl azides. The spent polymeric reagents can usually be removed and regenerated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Analysis of the heat of reaction and regeneration in alkanolamine-CO<Subscript>2</Subscript> system

The estimation of regeneration heat of absorbent is important because it is a key factor that has an effect on the process efficiency. In this study, thermal stability and regeneration heat of aqueous amine solutions such as monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), N-methyldiethanolamine (MDEA), and 1,8-diamino-pmenthane (KIER-C3) were investigated by using TGA-DSC analysis. The thermal characteristics of the fresh and CO₂ rich amine solutions were estimated. The CO₂ rich amine solutions were obtained by VLE experiments at T=40 °C. The regeneration heat of aqueous MEA solution was 76.991–66.707 kJ/mol-CO₂, which is similar to heat of absorption. The reproducibility of the results was obtained. The regeneration heat of aqueous KIER-C3 20 wt% solution (1.68 M) was lower than that of aqueous MEA 30 wt% solution (4.91 M). Therefore, the KIER-C3 can be used as an effective absorbent for acid gas removal.     

Promoting the CO2 adsorption in the amine-containing SBA-15 by hydroxyl group

Novel CO₂ capturer with a high efficiency is fabricated through dispersing the amine mixture of tetraethylenepentamine (TEPA) and diethanolamine (DEA) or glycerol within the as-synthesized mesoporous silica SBA-15, and the resulting sample is characterized by low angle X-ray diffraction and N₂ adsorption to evaluate the distribution of the guest. The influence of hydroxyl group on the CO₂ adsorption capacity of the composite is investigated by using CO₂-TPD and TG–MS techniques. The hydroxyl group of the P123 ((EO)₂₀(PO)₇₀(EO)₂₀, template preserved in as-synthesized SBA-15) and the guest could promote the capture of CO₂ by the amine through changing the interaction mechanism. In addition, the presence of hydroxyl group promotes the formation of the intermediate between CO₂ and the amine with a lower thermal stability hence the CO₂ trapped by the composite is easier to be desorbed and thus the regeneration of adsorbent is facilitated. Therefore, using this mixed amine (TEPA and DEA) modified as-synthesized SBA-15 as CO₂ capturer not only saves the energy for removal of template, but also cut down the cost in the preparation and regeneration of CO₂ capturer, which is critical in CO₂ separation and capture.     

Determination of Primary Amine Content in Bonding Agent Used in Composite Solid Propellants

The primary amine content in tetraethylenepentamine (TEPA) and TEPAN, a bonding agent used in composite solid propellants, was determined by near infrared (NIR) spectroscopy and the results were compared to those obtained by potentiometry. The band at 4930 cm⁻¹, which showed to be influenced only by primary amine groups, was chosen as the analytical band. The calibration curves based on isopropylamine (IPA) and isopropylamine/dibutylamine (IPA/DBA) mixtures proved to be suitable for determining the NH₂ content of TEPA or of samples containing mixtures of NH and NH₂ groups. It was found that TEPA contains 26.4 % of NH₂ and 25.7 % of NH, and that TEPAN contains 0.5 % of NH₂, confirming the low content of primary amine of this bonding agent. The lowest amine equivalent of TEPA is 31.1±0.3 g/eq, as determined by potentiometry, was found because this technique measures the total hydrogen content, including primary and secondary amines. The literature value of 62.6 g/eq for TEPA ACROS obtained by potentiometry in a non aqueous medium and related to the first inflection of the primary amine, validates the value obtained by NIR in this work for a similar type of amine. The equivalent weight obtained by NIR spectroscopy (62.7 g/eq) allowed to calculate the molar mass of TEPA of 195.6 g mol⁻¹, which is close to the typical value of 200 g mol⁻¹.     

Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

Comparison of solvent performance for CO2 capture from coal-derived flue gas: A pilot scale study

The performance of a proprietary solvent (CAER-B2), an amine-carbonate blend, for the absorption of CO₂ from coal-derived flue gas is evaluated and compared with state-of-the-art 30 wt% monoethanolamine (MEA) under similar experimental conditions in a 0.1 MWth pilot plant. The evaluation was done by comparing the carbon capture efficiency, the overall mass transfer rates, and the energy of regeneration of the solvents. For similar carbon loadings of the solvents in the scrubber, comparable mass transfer rates were obtained. The rich loading obtained for the blend was 0.50 mol CO₂/mol amine compared to 0.44 mol CO₂/mol amine for MEA. The energy of regeneration for the blend was about 10% lower than that of 30 wt% MEA. At optimum conditions, the blend shows promise in reducing the energy penalty associated with using industry standard, MEA, as a solvent for CO₂ capture.     

AEP-DPA-CuO相变纳米流体吸收CO2稳定性

化学吸收法CO₂捕集技术的核心是吸收剂,吸收剂的稳定性是实现CO₂捕集装置长周期连续运行的关键。本文针对0.6mol/L AEP-0.4mol/L DPA-0.1mol/L ACT相变有机胺吸收体系高温、含氧等条件下降解会带来腐蚀增强、吸收剂损耗的技术难题,进行了降解组分分析,研究了降解的主要影响因素。研究发现,CO₂负载、O₂、温度对降解率均有较大影响,其中影响因素排序为CO₂＞O₂＞温度,Fe³⁺对氧化降解影响大于对热降解的影响。通过GC-MS分析可知,热降解热稳定盐主要有3种,氧化降解热稳定盐主要有6种。为抑制热降解与氧化降解,研究选取酒石酸钾钠等6种抗氧化剂进行考察,得到最佳抗氧化剂为丙酮肟,最佳添加量为800mg/L,其中热降解抑制率为97.9%,氧化降解抑制率达到98.3%,实现了AEP-DPA-ACT相变体系的低降解率,为相变纳米流体的稳定运行提供了保障。     

Liquid crystalline H-bonded polymers influenced by chiral and achiral spacers

La₂O₃/polybenzoxazine composite was prepared through incorporating La₂O₃ into benzoxazine based on phenol and 4,4??-diaminodiphenyl methane (BB) to study the effect of La₂O₃ on the thermal stability of crosslinked polybenzoxazines. The ring-opening polymerization of BB benzoxazine was analyzed by DSC and measurement of viscosity. The structure and the thermal stability of BB polybenzoxazine were characterized by FTIR, TGA and DMA. The thermal degradation processes of polybenzoxazine were investigated using TGA-FTIR. The results showed that La₂O₃ could form coordination interaction with the nitrogen atoms of BB and thus promoted the polymerization of BB benzoxazine. The coordination interaction could not influence the volatilization of the amine degradation gases during the thermal degradation process of BB polybenzoxazine due to the amine structure existing in the chemical crosslinking network of polybenzoxazine and being stable. Furthermore, the coordination interaction weakened the C-N and C-C bonds in CH₂-NR-CH₂- of BB polybenzoxazine and thus accelerated the appearance and volatilization of the phenolic gases during the thermal degradation process, resulting in the decrease of the thermal stability and char yield at 800?°C of BB polybenzoxazine.