尿素装置工艺冷凝液水解技术

我国小尿素原设计工艺冷凝液经解吸塔处理后排放,解吸残液含氨0.07%(质量分率),含尿素1.1%(质量分率).由于绝大多数尿素装置的生产能力大大超过原设计值,最高已达500 t/d,而工艺冷凝液处理设备基本没有改造.因此,实际生产中经解吸塔处理后排放的解吸残液含氨及尿素比原设计值还要高,这不仅对环境保护极为不利,而且增加了消耗,提高了产品成本.     

尿素工艺冷凝液高温深度水解处理技术

该厂尿素工艺冷凝液由于采用了高温深度水解处理技术,长期稳定达标,并变废为宝,每年获利853.7万元.文章介绍了此项技术之原理与工艺等。     

利用深度水解技术处理尿素工艺冷凝液

采用立式水解塔深度水解技术处理尿素系统产生的工艺冷凝液，将氨氮指标降到1^-6级。     

二氧化碳汽提法和氨汽提法尿素深度水解工艺比较

介绍斯纳姆氨汽提法和斯塔米卡邦二氧化碳汽提法两种尿素深度水解工艺,分析它们在工艺条件上的不同选择原因,比较了各自的特点。     

尿素工艺冷凝液的深度水解处理技术

根据尿素工艺冷凝液深度水解的工作原理,运用其工艺流程,将尿素经过深度水解后回收有用物质,这种废弃物再度利用不仅节省能源还起到了保护环境的作用,同时也产生了一定的社会经济效益。     

改造水解系统回收尿素工艺冷凝液

结合我公司生产实际，对尿素工艺冷凝液不能回收的原因进行分析，通过增设板式换热器及电导分析仪解决问题，并针对改造后运行中存在问题及解决措施进行了总结。     

尿素装置工艺冷凝液水解解吸技术

介绍了几种具有代表性的尿素工艺冷凝液水解解吸技术，比较了它们各自的技术特点，表明了今后应用和推广的前景。     

CO_2汽提法尿素装置解吸水解系统工艺优化设计

介绍了30万t/a二氧化碳汽提法尿素装置解吸水解系统的技术发展过程;针对运行中出现的问题和新技术的工业化应用业绩,对新建装置解吸水解系统进行了优化设计;总结了装置生产运行效果。解吸水解系统工艺运行数据表明,优化设计达到预期效果。     

尿素工艺冷凝液深度水解装置通过专家鉴定

受宁波市科技局委托,由业内资深尿素专家组成的鉴定委员会,11月24日在温州通过了对宁波远东化工科技有限公司开发的尿素工艺冷凝液深度水解装置的技术鉴定。专家委员会在听取了有关方面的情况介绍以后,对该公司提交的工艺和设备图纸、试制总结报告以及用户投产和运行报告等技术文件进行了认真仔细的审议,一致认为：     

工艺冷凝液水解系统的改造

分析尿素装置水解系统处理后的工艺冷凝液不合格的原因及改造情况,并对改造后系统运行做了总结。     

Experimental Studies on the Catalytic Distillation for Hydrolysis of Methyl Acetate

In this paper, the feasibility of applying catalytic distillation for the hydrolysis of methyl acetate is studied experimentally. An optimum technological process for the hydrolysis is determined, based on experimental results and mathematical simulations. The methyl acetate conversion can be greatly increased, and the energy consumption reduced, for certain operation conditions via the catalytic distillation process.     

尿素工艺冷凝液深度水解装置的生产运行

介绍了尿素装置工艺冷凝液的深度水解处理过程;从工艺角度分析了其主要设备--解吸塔和水解塔的生产运行过程,提出了选择最佳工艺操作指标的原则;分析了解吸水解系统在生产运行中存在的主要问题和原因,提出了生产操作控制要求和整改措施.     

尿素解吸水解系统技改小结

介绍了尿素解吸水解系统在实际运行中出现的问题及针对问题进行的一系列技术改造和改造后的运行情况。     

Process alternatives for methyl acetate conversion using reactive distillation. 1. Hydrolysis

In a polyvinyl alcohol (PVA) plant, reaction stoichiometry indicates that equal molar of methyl acetate is generated for every mole of PVA produced. This work explores an alternative to convert methyl acetate back to acetic acid (raw materials of PVA plant), methyl acetate (MeAc) hydrolysis. The design and control of methyl acetate hydrolysis using reactive distillation is studied. Because of the small chemical equilibrium constant (∼0.013) and unfavorable boiling point ranking (MeAc being the lightest boiler), the reactive distillation exhibits the following characteristics: (1) total reflux operation and (2) excess reactant (water) design. The proposed flowsheet consists of one reactive distillation column with a reactive reflux drum, two separation columns, and one water-rich recycle stream. A systematic design procedure is used to generate the flowsheet based on the total annual cost (TAC). Two dominate design variables are: recycle flow rate (for the degree of excess in water) and the overhead impurity level of acetic acid in the product column (to avoid tangent pinch). Finally, the operability of the hydrolysis plant is evaluated. A plantwide control structure is developed followed by process identification and controller tuning. The results show that reasonable control performance can be achieved using simple temperature control for feed flow and feed composition disturbances.     

Computational Fluid Dynamics Modeling for Urea Hydrolysis in a Batch Reactor for Flue Gas Conditioning

A computational fluid dynamics (CFD) model is proposed to simulate urea hydrolysis for ammonia synthesis as a safe feed stock to flue gas conditioning in thermal power plants. A series of parametric studies to investigate flow rates, thermal boundary conditions, and reactor geometry was performed and operating conditions and reactor geometry were optimized. Detailed 3D flow, heat, and chemistry simulations of ammonia were carried out with predicted conversions comparable to measurements and the dependence of the experiments on the reaction parameters was evaluated. Through simulation under the same conditions the output was generated and compared to the experimental plot. Profiles of temperature and flow patterns were successfully achieved through simulation.     

Systematic retrofit design with Response Surface Method and process integration techniques: A case study for the retrofit of a hydrocarbon fractionation plant

This paper demonstrates the Retrofit Design Approach (RDA) and Response Surface Methodology (RSM) for the retrofit of industrial plants in which assessment of design options for improving existing processes in a site-wide and integrated manner is not straightforward, due to complex design interactions in the process. The design methodology applied in this study is based on the systematic use of a process simulator which is used to identify promising variables through sensitivity analysis. Hence, the most important factors are determined and a reduced model is constructed based on RSM. An optimization framework is then built using the reduced model based on key selected variables, which is optimized to find optimal conditions and performance of the process. This design methodology provides strategic guidelines for determining the most cost-effective design options. The retrofit of a hydrocarbon fractionation plant is presented as an industrial case study. This includes a large number of design options with different process configurations and operating conditions due to the interconnection of distillation columns in sequence and the integrated heat recovery within the plant. The case study results demonstrate the applicability of the proposed approach which is able to effectively deal with a large retrofit problems. This is possible with the aid of process simulation and RSM producing a reduced model which requires considerably less computational effort to solve.     

Process Intensification for the Recovery of Hydrogen Cyanide in the Andrussow Process

The aim of this work was to determine a cost-optimal design of the distillation unit of the Andrussow process. For this purpose, a feed with a mass flow rate of 121 t h⁻¹ and a concentration of ca. 2 wt % hydrogen cyanide (HCN) was considered. An approach for a cost-optimal process intensification was developed with the goal to achieve the desired product qualities, while minimizing the organonitrile accumulation in the column. For this purpose, the simple distillation column of the established cost-optimal design of the base case was extended to a configuration with a side stripper with taking into consideration heat integration in the process. It was found that this new configuration allows a much smaller accumulation of organonitriles in the main column; reducing thereby the operation issues of the process while decreasing considerably the total annual cost of the distillation unit by 61 % as compared to that of the base case design.     

Noncatalytic Hydrolysis of Iminodiacetonitrile in Near‐Critical Water – A Green Process for the Manufacture of Iminodiacetic Acid

The hydrolysis of iminodiacetonitrile (IDAN) in near‐critical water, without added catalysts, has been successfully conducted with temperature and residence time ranges of 200–260 °C and 10–60 min, respectively. The effects of temperature, pressure, and initial reactant/water ratio on the reaction rate and yield have been investigated. The final reaction products primarily included iminodiacetic acid (IDA) and ammonia associated with other by‐products; gas formation was negligible. The maximum yield of IDA was 92.3 mol.‐% at 210 °C and 10 MPa, with a conversion of almost 100 %.The apparent activation energy and ln A of IDAN hydrolysis were evaluated as 45.77 ± 5.26 kJ/mol and 8.6 ± 0.1 min^–1, respectively, based on the assumption of first‐order reaction. The reaction mechanism and scheme were similar to those of base‐catalyzed reactions of nitriles examined in less severe conditions.     

关于二氧化碳汽提法尿素装置汽提塔的腐蚀与维护

CO2汽提塔是二氧化碳汽提法尿素装置的4大重要高压设备之一。简述了1000 t/d CO2汽提塔的工艺过程、基本结构和使用情况;从材质、负荷、保温、操作、维护等方面论述了CO2汽提塔产生腐蚀的影响因素;提出了控制腐蚀的技术措施和维护要求。