螺旋式浓硝酸漂白塔的开发研制和应用

针对传统的帽罩式浓硝酸漂白塔存在的缺点和不足,找出原因并予以改进,开发研制出螺旋式浓硝酸漂白塔,改进了工艺状况,减少了维修工作量,达到了节能降耗的目的,确保了直接法生产浓硝酸装置的长周期运行。     

螺旋式浓硝酸漂白塔的开发研制和应用

针对传统的帽罩式浓硝酸漂白塔存在的缺点和不足,找出原因并予以改进,开发研制出螺旋式浓硝酸漂白塔,改进了工艺状况,减少了维修工作量,达到了节能降耗的目的,确保了直接法生产浓硝酸装置的长周期运行。     

直硝装置浓硝酸漂白塔结垢原因及防范措施

浓硝酸漂白塔是直接法生产浓硝酸(俗称直硝)的主要设备之一,其主要工艺用途是:利用蒸汽间接加热含有25%～35%N2O4的浓硝酸(俗称发烟硝酸),通过热力漂白脱硝,使酸中N2O4脱解,从而获得符合国家标准的浓硝酸产品,并为合成浓硝酸提供N2O4原料。直硝装置浓硝酸漂白塔运行工况是否稳定不仅影响到成品浓硝酸的产品质量,而且还影响到合成浓硝酸     

浓硝酸漂白塔设备技术改造

浓硝酸漂白塔易发生泄漏和筒体局部严重腐蚀,找出原因并以改进,延长其使用寿命,确保浓硝装置安全、长周期运行。     

升举穿流塔板在浓硝漂白塔中的应用

介绍了兰化漂白塔生产状况，针对漂白塔生产特点，结合漂白塔多次改造经验，提出了漂白塔塔板选用原则。通过分析升举穿流塔板及其性能，认为升举穿流塔板是漂白塔的优选塔板。浓硝酸装置采用升举穿流塔板后取得明显效果。并谈了几点实际应用设计中需注意的具体问题。     

发烟硝酸漂白塔的技改

我公司60kt／a浓硝酸装置采用的是直接法生产工艺，发烟硝酸漂白塔是关键设备之一，其作用是将发烟硝酸中的二氧化氮与浓硝酸分离。该塔分上、下2段，上段为精馏段，下段为蒸发段，为蒸汽夹套式，塔内一直沿用前苏联泡罩式气液传质结构，简体采用高纯铝板卷焊而成。该设备于20世纪60年代末投入运行，运行过程中由于蒸发段塔内侧与72～82℃浓硝酸接触，铝筒中间的纵焊缝极易腐蚀，实际运行周期很短，     

一台KMM调节器对两个漂白塔进行选择前馈—串级控制

一、概述浓硝酸生产中的漂白塔,是用蒸汽加热进入该塔的冷、热发烟硝酸,除去酸中的NO_x气体而漂白出合格的成品酸。成品酸的质量合格与否取决于冷、热混合酸入塔的温度和量的大小,以及入塔的蒸汽用量、出塔酸温度等。本文介绍采用KMM调节器对漂白塔进行控制的方案:以出塔酸温作主参数、入塔酸温作前馈参数、入塔蒸汽压力作     

浓硝酸装置漂白塔结构改造

通过对浓硝酸生产的关键设备漂白塔生产能力较低原因的分析,在原塔基础上采用将塔头和上段合二为一、增加两块溢流板和改变上段塔板类型的方法进行改造。     

硝酸镁法生产浓硝酸工艺技术的优化

针对硝酸镁法生产浓硝酸中仍存在自动化程度低、浓缩塔和漂白塔性能差、单塔产量低、消耗高、现场污染较大、酸性废水外排量大、未能有效利用等问题,认真分析并进行了一系列优化,既提高了生产的性能和产品的质量,又节约了成本,取得了良好的效果。     

S型卸料器的结构对塔底稀释区流场的影响

引 言 由于高浓漂白具有化学传质效率高、消耗蒸汽少等优点,已在造纸工业中被广泛采纳[1].然而高浓纸浆流动性差,通常在高浓漂白塔塔底需要功率较大的螺旋输送器进行输送,然后再增加稀释单元.因此,研究高浓纸浆降流漂白塔卸料器输送浆料的特征对于节约能源和节省空间以及对卸料器的设计和改进,都将具有很重要的意义.     

A Chemical Exchange System for Isotopic Feed to a Nitrogen and Oxygen Isotope Separation Plant

Abstract

A process has been developed to provide isotopic feed to a nitric oxide isotope distillation plant. Central to the process is the isotopic chemical exchange of NO and nitric acid in countercurrent flows in a 3-in. diameter packed column. An isotopically depleted stream of NO is reenriched to natural isotopic abundances by the exchange and is recycled as feed back to the distillation columns. Makeup NO is generated in another column from sulfur dioxide and nitric acid. Multistage gas purifiers reduce condensible impurities in the nitric oxide below 10 ppm. The process operates unattended at flow rates of 0.5 to 2 mol/min. The new NO recycle-enrichment and generation processes have successfully provided the feedstock for the NO isotope separation columns for over 6 years.     

Modeling and simulation of a nitric acid recovery process

A nitric acid recovery process using composite distillation columns was modeled and simulated. The composite distillation columns consist of a multistage vacuum tower and an atmospheric pressure tower half of which consists of packed bed. The vacuum tower and the atmospheric pressure tower were modeled by using equilibrium stage method and non-equilibrium stage method respectively. The required thermodynamic properties for nitric acid solution were obtained from correlations based on experimental data. Results of simulations showed good agreement with actual plant data. From the results of simulations it was found that the upper half of the atmospheric pressure column and the vacuum column, consisting of plate column, can be modeled using equilibrium model, but the lower half of the atmospheric pressure column, which are packed parts, can be modeled effectively using non-equilibrium model. The non-equilibrium model developed in the present study showed good agreement with actual operaton data.     

Nitric acid purification from admixtures of volatile acids by fractionation during waste evaporation at a spent nuclear fuel reprocessing company

We present the results of the computer simulation of a method for better purification of nitric acid from HF and CH₃COOH admixtures by creating a stripping section in the fractionation column with HNO₃ scrubbing and by the feeding of a parasitic water flow to the bottom section. The production column in the evaporator section of the RT-1 plant at the PA ??Mayak?? was upgraded using the calculation results and test trials on real process high-level waste were performed, which made it possible to improve the purification of regenerated 12 mol/L HNO₃ from HF and simultaneously from HCl by a factor of 3?C5. The specification figures for three flowsheet of nitric acid regeneration that were used at different times since 1979 for commercial purification from halogens and radioactive contaminants were compared.     

硝酸镁法浓硝酸工艺技术及装置大型化探讨

比较了浓硝酸生产的几种方法,介绍了浓硝酸主流工艺硝酸镁法制浓硝酸三元相图的实际应用情况及技术革新成果。提出了浓硝酸装置大型化的思路,建议先建设5万t/a的示范装置,并对其工艺技术、设备材质以及规格选型和计算,进行认真分析研究,为建设10万t/a、15万t/a大型装置奠定基础,以提升我国浓硝酸生产水平。     

大型常压稀硝装置的技术改造途径──吉化公司化肥厂“二硝”装置技术改造经验与体会

通过吉化公司化肥厂“二硝”装置的技术改造实践──我国第一套大型常压稀硝装置技术改造成功的经验与体会，结合我国实际情况阐述了常压法稀硝生产工艺及其生产装置技术改造的途径。     

超共沸酸精馏制取浓缩酸与联产多种浓度稀硝酸新工艺

通过对当前国内几种浓硝酸生产方法的分析与比较之后,提出超共沸酸精馏法制取浓硝酸的生产新方法,该法可实现装置大型化,同时实现质量分数40%~45%,55%~60%和68%的稀硝酸与浓硝酸联合生产。与同规模硝酸镁法制取浓硝酸相比,超共沸酸精馏法可节省建设投资约20%,吨酸节能30%、减排CO20.37 t、制造成本降低14%,是今后我国浓硝酸发展可供选择的生产方法。由于对硝酸质量分数在70%~90%区域的相关理论数据研究力度不够以及在该浓度下对设备材质的选用仍存在一定的疑虑,望今后以此作为课题进行研究,使超共沸酸精馏法制取浓硝酸早日实现工业化。     

变压吸附法处理硝酸尾气的研究

概述了硝酸尾气的处理方法，详述了变压吸附法处理硝酸尾气的原理，提出了处理尾气的工艺过程和工艺指标。     

国产100kt/a双加压法硝酸装置蒸汽不能自给原因浅析

从设备、机组、工艺等方面分析了国产100 kt/a双加压法硝酸装置蒸汽不能自给的原因。针对存在的问题,提出了改进建议,如提高"四合一"机组技术性能、提高工艺设计和设备制造水平、加强管理等,以使国产化双加压法硝酸装置赶上或达到世界先进水平。     

Intensification of nitrous acid oxidation

An alternative solution to the reduction of a discharge of residual nitric oxide and nitrogen dioxide into atmosphere has been proposed. Instead of using methane or ammonia for SCR or gas absorption into alkali solutions, which are the most popular treatment methods of tail gases, now the use of powerful oxidant—ozone capable of transforming nitrous acid and nitric oxides into nitrogen of the highest oxidation level—could be employed for this purpose. As the intensive oxidation and ozonation of nitrous acid is the heterogeneous gas-liquid process, the solubility of oxygen and ozone in HNO₂/HNO₃ aqueous solution was necessary to be determined. Variations of reaction rates depending on temperature, ozone dose and nitrous and nitric acid concentrations were studied experimentally. The kinetic model of the reactions, 2HNO₂+O₂→2HNO₃ and HNO₂+O₃→O₂+HNO₃, were proposed and the kinetic parameters (rate constants and activation energies) were estimated on the basis of experimental data in semi-batch laboratory gas-liquid contactor with the liquid phase drawn from an absorption column in the nitric acid plant. The determined kinetic parameters were then used in designing and modeling of the oxidation of nitrous acid using ozone-oxygen mixture in a continuous bubble column. The model consists of mass transfer kinetic equations and material balance equations for the gas and liquid phases. The co-current flow of gas and liquid phases and the complex kinetics of chemical reaction in the liquid phase were taken into account. The variation of the following process conditions, flow rate, compositions of the gas and liquid phases, temperature, and pressure in the bubble column of different diameters and heights, were studied in numerical solutions of the proposed model.     

硝酸装置“四合一”机组运行实践

双加压法硝酸装置中的“四合一”机组是整个稀硝酸装置生产的“关键”设备,喘振是压缩机组的主要缺点,以新建装置的生产实践为例,对喘振原因、影响因素、喘振消除以及在生产中应注意的事项加以阐述。