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利用共沸精馏回收稀硫酸新工艺开发和过程模拟
Alternative TitleProcess Development and Simulation of Dilute Sulfuric Acid Recovery by Azeotropic Distillation
李赓
Subtype博士
Thesis Advisor李志宝
2014-03
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword稀硫酸回收   共沸精馏   溶液热力学   汽液平衡   过程模拟
Abstract800x600 稀硫酸的浓缩回收再利用是许多冶金工业和化学工业部门经常遇到的难题,例如在利用硫酸工艺生产二氧化钛的生产中,钢铁企业和石油炼制等诸多工业,都副产巨量的稀硫酸需要浓缩回收循环利用。工业上早期所采用的主要方法是采用石灰中和并副产石膏,但生成的石膏会造成新的环境问题,而且硫资源没有得到有效利用。多效蒸发是目前工业上应用最广泛的回收方法之一,但仍存在着能耗高、腐蚀严重等问题。研发新的稀硫酸处理方法是当前科研机构和工业部门的研究热点,如喷雾干燥、溶剂萃取和扩散渗析等方法,但这些方法离工业化还有距离。论文提出了采用共沸精馏技术来回收稀硫酸的新工艺,能够采用低品位的水蒸汽来浓缩稀硫酸。新工艺主要由三个精馏塔组成:(1) 共沸精馏塔。稀硫酸和补充的共沸剂一起从共沸精馏塔中部进料,从塔顶馏出的蒸汽经冷凝分相后,油相回流返回共沸精馏塔,而水相经泵打入共沸剂回收塔,塔底为浓缩后的硫酸进入硫酸塔;(2) 共沸剂回收塔。回收来自共沸精馏塔和硫酸塔水相中的共沸剂,塔底排出水;(3) 硫酸塔。塔底得到浓缩的硫酸,返回工艺系统循环使用。论文围绕此新工艺的过程模拟和所涉及的相关体系的汽-液和汽-液-液平衡数据测定和热力学模型的建立开展工作,取得如下成果:(1) 建立了一套测定互溶体系汽-液平衡(沸点)和直接测定不互溶体系汽-液-液平衡(共沸温度)的实验装置,并测定了如下体系的汽-液和汽-液-液平衡数据:(1) C6H12O2(乙酸丁酯)+H2O+C6H12(环己烷)+C2H6O(乙醇)、(2) H2SO4+H2O+C6H12O2+ C2H6O、(3) H2SO4+H2O+C8H18(辛烷)+C2H6O和(4) H2SO4+FeSO4+H2O+C6H12。(2) 建立了上述含硫酸和共沸剂相关体系的化学模型。在考虑中间组分如HSO4–和H2SO4(分子)部分电离化学平衡的基础上,通过回归实验数据分别得到电解质NRTL和混合溶剂电解质(MSE)模型参数,并在Aspen Plus 和OLI Systems平台上建立起个人数据库,便于过程模拟计算时使用。建立的化学模型计算值与实验值符合较好,最大平均偏差仅为0.83 K。此外,还直接利用不互溶体系的总组成和共沸温度数据成功回归了相应的模型参数,也取得良好的关联结果。(3) 采用半连续的精馏实验装置对论文提出的硫酸沸精馏回收新工艺的可行性进行了实验验证。首先对不同类型的共沸剂进行了考察,包括环己烷、辛烷、异辛烷和乙酸丁酯,结果发现当以环己烷作为共沸剂时,在保证一定的带水容量下,可以明显降低塔釜的加热温度。通过调节塔釜加热功率和进料速率,可以成功将20%的稀硫酸浓缩至60%以上,此时精馏塔塔釜温度仅为373 K,比60%硫酸的正常沸点低了约40 K,使利用低品位蒸汽精馏稀硫酸成为可能,从而验证了新工艺流程的工业可行性。(4) 利用AspenPlus为计算平台,结合新建立的化学热力学模型,对以环己烷为共沸剂的稀硫酸三塔共沸精馏回收工艺进行了过程模拟计算,并与精馏小试实验数据进行了对比,取得良好的模拟效果。流程过程模拟结果表明:以环己烷为共沸剂,采用共沸精馏来浓缩稀硫酸可有效降低精馏塔塔釜的温度仅为361 K,从而实现了以工厂副产的低品位蒸汽为热源浓缩稀硫酸的目标。对于一个年产5万吨钛白粉的工厂,其生成的所有稀硫酸的浓缩可以使用一个理论板数为4、直径为4.56米的精馏塔来实现,浓缩后硫酸的浓度可达60%以上。 
Other AbstractThe recovery of dilute sulfuric acid is a difficult problem encountered in many metallurgical and chemical industrial sectors such as in TiO2 production (sulfuric acid process), steel plants, and oil refining etc. A huge amount of dilute sulfuric acid generated should be recovered and recycled for reuse . The main method used in early industry is to neutralize dilute sulfuric acid by lime to produce gypsum, but the resultant gypsum causes a new environmental problem and the sulfer resource is not sufficiently used. Multistage evaporation has been most widely used in industry nowadays, but it is considered rather energy-intensive. Development of new sulfuric acid treatment method is a research hotspot in research institutes and industrial sectors currently, such as spray drying, solvent extraction, electrodialysis, etc. However, they are not under the way for industrial application. A new method for the recovery of dilute sulfuric acid by azeotropic distillation is proposed in this dissertation, and a low grade steam may be used as the heating source. This process mainly consists of three distillation columns: (1) Azeotropic distillation column. The dilute sulfuric acid and the make-up entrainer are fed into the azeotropic distillation column. The overhead vapor from column is condensed and separated in the decanter where the oil phase is returned to the distillation column as reflux. The water phase is delivered to the entrainer recovery column, the enriched sulfuric acid from the bottom is pumped to the acid column. (2) Entrainer recovery column. The entrainer is recoverd from the water phase from azeotropic distillation column and sulfuric acid column, and the water is discharged from the bottom. (3) Sulfuric acid column. Enriched sulfuric acid is obtained from the bottom of the column, and then sent for reuse. The research is about the measurement of vapor-liquid (VLE) and vapor-liuqid-liquid (VLLE) data, as well as the establishment of the thermodynamic model, of the system relating to the development and simulation of the new process. The main results are obtained as follows: (1) A set of experimental apparatus was established for measuring the boiling point of miscible systems and the azeotropic temperature of the immiscible systems. The VLE and VLLE data for the following systems were determined: C6H12O2(butyl acetate)+H2O+C6H12(cyclohexane) +C2H6O(ethanol), H2SO4+H2O+C6H12O2+C2H6O, H2SO4+C8H18(octane)+H2O+C2H6O, H2SO4+ FeSO4+H2O+C6H12.(2) The chemical models for the above-mentioned systems were established. Considering the dissociation equilibrium of middle species (HSO4– and H2SO4 molecule), the model parameters for NRTL, electrolyte NRTL, and Mixed Solvent Electrolyte (MSE) models were regressed from the experimental data. In order to facilitate the process simulation and calculation, the private databanks were built by using Aspen Plus and OLI platforms. The calculated results from the newly built chemical model agreed with the experimental data well, with the average deviation of temperature of 0.83 K. In addition, the model parameters were successfully obtained directly by regressing the experimental azeotropic temperature data and the overall composition of the heterogeneous systems with a good result. (3) The feasibility of the new azeotropic distillation process was verified by the semi-continuous distillation experiment. Various entrainers, including cyclohexane, octane, isooctane, and butyl acetate, were investigated. The results show that, when cyclohexane was used as the entrainer, the temperature of the column bottom was significantly reduced. By carefully adjusting the heating power and the feed speed, the diluted sulfuric acid can be enriched from a concentration of 20% to 60% or above, with the distillation column bottom temperature of only 373 K. This is about 40 K lower than the boiling temperature of a 60% sulfuric acid. This indicates that a lower grade quality heating steam is required and thus the
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/15545
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
李赓. 利用共沸精馏回收稀硫酸新工艺开发和过程模拟[D]. 中国科学院研究生院,2014.
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