Research On Naphtha Dearomatization Process Technology

There are many ways to separate aromatics from naphtha, such as extraction method, hydrogenation saturation, adsorption and membrane separation, etc. However, the dearomatization extraction is the most mature technology with various corresponding processes, including liquid-liquid extraction process which are Sulfolane process, Udex process, Tetra process, extractive distillation process which are ED SulfolaneTM process, Distapex process, Morphylane process, GT-BTX technology, Jin-WeiHui SUPER-SAE-Ⅱ technology, SED-Ⅱ Process etc. Extraction solvents used in the extraction method has a great range of options, such as common solvent sulfolane, N-methylpyrrolidone, triethylene glycol, 2-propanol, dimethyl sulfoxide and so on. Till now, the above processes can do with the feedstock of high aromatic content, usually above 30% mass frcation,while, there is no better process that could deal with the feedstock of low aromatic content(mass fraction less than 10%).Through this centrifugal extractor experiment, this paper select a group of co-solvent NMP-DMF-H2 O which could extract aromatics from straight-run naphtha feed with low aromatic content. This experiment made aromatics removal rate reached 99.9%, then this paper designed a new process based this experiment results.The software Aspen Plus can be used to design and calculation naphtha dearomatization process. Through strict energy and mass balance calculation process,it can forecast flow rate, composition and properties, process parameters, equipment size, thereby reducing the design time of the device,it also can can be used to compare various design schemes,Using this software, you can save time time and material costs as well as improve design efficiency. In order to facilitate the simulation calculation, this paper had to take a better way to simplfy the complex naphtha feedstock. This paper divided the detail group of normal naphtha into four groups,paraffins, isoparaffins, naphthenes, aromatics, then select the 30 kinds of typical components to express naphtha. According to the material being processed, this paper selected the recommended property method NRTL to be the process simulation calculations method. This paper use the UNIF-DMD group contribution method to estimate the missing Binary interaction parameters of all the components.Using the software Aspen Plus, this paper designed a naphtha dearomatization process calculation model which can deal with 100 thousants t·a-1of naphtha feedstock. In order to improve the paraffin recovery rate of naphtha,this paper use distillation tower to recycle the light component(Boiling point lower than 60℃of alkanes)in the naphtha before extraction process, and then use strict extraction block to achieve the initial separation of aromatics and alkanes. From the last process this paper get the dearomatization extraction raffinate phase and the extraction phase which are rich in aromatic components, after then still use the strict extraction block to wash out the solvent from the raffinate phase. In the design of the separation rich aromatics extraction phase. A simple check block was used to obtain the initial value, before use the strict distillation column block. At last the rich aromatic components and composite solvent components was separated by distillation methods.After the continuous optimization of the parameters of each block, the final calculation of the whole process converged. Through this process calculation model, After the continuous optimization of the parameters of each block, the final calculation of the whole process converged. Through this process calculation model, the dearomatized naphtha yield was 79.04%, the content of alkanes was 99.03%, aromatic hydrocarbon content is 0.86%, the water content is 0.10%, the solvent content is 0.005%, the obtained dearomatized naphtha meet the requirements. The rich aromatic oil yield was 20.96%, the aromatic content of the oil increased to 41.41%. Aromatics enrichment effect is obvious. Through the process simulation, a design of 100 thousand tons / year naphtha dearomatization plant and process was made,the basic design parameters was obtained.