PTQ Q1 2023 Issue

Universal filter for ultra-cleaning of reactor streams Magnetically induced filter removes solid particles to protect catalyst active pore openings from plugging Fu-Ming Lee, Mark Zih-Yao Shen, Chi-Yao Chen, Maw-Tien Lee, Yin-Hsien Chen, John Lee and Stephen Yen Shin-Chuang Technology Co., Ltd. Kao-chih Ricky Hsu International Innotech, Inc.

A magnetically induced filter has been developed and commercially implemented to remove essentially all types of solid particles of any size (down to 7 nm or less) with substantially reduced costs and simpler opera - tions. The impact of nanometer particles removal from liquid streams to the reactor is huge since it protects (or minimises) catalyst active pore openings from plugging, thereby greatly prolonging the catalyst life. Minimising solid particles Pipelines and equipment seen in refineries and petrochemi - cal plants are generally made with carbon steel, which is subject to corrosion by hydrogen sulphide (H2S), organic sulphur compounds, and other acidic compounds in crude oil and in-plant petroleum or petrochemical streams. Corrosion of carbon steel equipment generates iron sul - phide (FeS), iron oxides (FeO/Fe2O3), and other metal- containing solid particles in the process streams, which may cause severe plugging problems in fixed-bed reactors, lines, valves, and pumps. The solid particles are removed from liquid streams mainly by filtration. The following methods are currently used to minimise the solid particles in the feed stream before entering the reactor:  Conventional filter cartridges and/or filtering screens are normally used to remove only large solid particles (larger than 25-50 microns) from process streams. They are easily plugged by the solid particles and require fre - quent cleaning or costly cartridge replacement, disrupting process operations at significant costs. Furthermore, fre - quent cleaning and filter cartridge replacement increase the chance of air (oxygen) getting into the filter and reac - tor, promoting polymerisation of dienes and olefins in the reactor, which causes even more severe pressure drop and plugging problems. To remove additional particles from the liquid stream and provide a better fluid distribu - tion, macropore solids are also packed into the top of the reactor.  In recent years, reticulated top bed materials have been packed in the top of the reactor to improve solid par - ticles removal and fluid distribution into the catalyst bed, thereby minimising pressure drop and promoting reactor performance. Depending on the types of reticulated top bed materials, additional solid particles with sizes larger

than 1.0 micron are removed from the liquid stream before reaching the active catalyst bed. It should be noted that the conventional methods are designed to remove micron-size (10 -6 m) solid particles only and are incapable of removing ultra-small nanometer (10 -9 m) particles from the process streams. For example, the reticulated top bed technology can only remove solid par - ticles from 1-1,500 microns in size. Unremoved ultra-small particles in the liquid stream tend to plug the pore opening of the catalyst active sites in the downstream reactor. Pore size distribution (PSD) of commercial hydrodesul - phurisation (HDS) catalysts for treating petroleum or coal tar liquids is in nanometer ranges. Two examples are listed as follows:  For HDS of FCC gasoline, a CoMoS/Al2O3 catalyst was prepared with the alumina having tri-modal pore distribu - tion at approximately 5-8 nm, 15-20 nm, and 90-100 nm. 1  For HDS of vacuum resid, a high activity catalyst having a unimodal with maximum pore volume in the medium meso - pore range (within 10-25 nm diameter) was prepared. 2 Therefore, it is highly desirable to develop a filter capable of effectively removing solid particles of all sizes from the reactor streams, including the ultra-small nanometer-size particles, to protect the catalyst pores from plugging at reduced costs. Filter performance Shin-Chuang Technology (SCT) Co.’s magnetically induced Universal Filter removes all types of solid particles down to 7 nm or less at substantially reduced cost and simpler operation. This filtration system achieves a near-total pre - vention of solid particles in the liquid stream from entering the reactor. Furthermore, the need for expendable macropore filtra - tion packings in the reactor and filter cartridges at reac - tor feed entry is substantially eliminated (or minimised) to save material and operational costs, which include loading/ unloading and disposal of the spendable materials. The only requirement is that the solids in the liquid stream contain certain amounts of ferromagnetic (FM) substances, such as FeO, FeS, Fe2O3, Ni, NiO, Co, and CoO. In fact, solid particles in liquid streams feeding to HDS reactors for treating light coal tar from steel mills and FCC gasoline, straight-run naphtha, diesel, and kerosene fuels


PTQ Q1 2023

Powered by