ECN publication
Skid mounted pervaporatie unit op basis van anorganische membranen : bouw en in gebruikname van de unit
Published by: Publication date:
ECN Energy Efficiency in Industry 1-9-2001
ECN report number: Document type:
ECN-C--01-040 ECN publication
Number of pages: Full text:
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The Netherlands has a leading role in the development of ceramic membranes for pervaporation. These membranes can be prepared in a tubular geometry on a larger scale and can be used in the dewatering of organics, leading to better and cheaper separation processes. However, implementation is difficult, as it is a new technology, not familiar yet to potential end-users. Therefore further testing should be performed on a reasonable scale on site of the end-users.The aim of this project is to design, build and test a pervaporation test installation based upon silica membranes with a membrane area of about 1 m2. The test unit is to be used on-site at end-users. To anticipate the performance of the unit, lab-scale measurements with small membrane samples were done. Four dewatering processes were chosen: 1. n-butanol including formaldehyde contamination?s for Akzo Nobel Resins, 2. DMF with several contaminants like salts and particles for Caldic Chemical Production BV, 3. a multicomponent water-organic waste mixture for Diosynth, 4. a propylene glycol mixture for Lyondell. Lab scale dewatering of the butanol (and formaldehyde) stream at 75oC by pervaporation and dewatering of the organic waste mixture of Diosynth via vapour permeation shows very good separation results and good fluxes, which meet the criteria of the end-users. The dewatering of DMF in a continuous process mode is possible and meets the specifications set by Caldic. Batch-wise dewatering, however, leads to a reversible flux decline due to the deposition of salts on the membranes, which are present in the feed mixture. These salts can be removed by washing with soap. Dewatering of glycols for Lyondell by pervaporation gives very high water fluxes and selectivities, however a flux decline is observed in time, probably due to fouling by the viscous glycol. A detailed design of the installation was made in co-operation with Sulzer Chemtech, the contractor to build the installation. This design was based upon several discussions with the end-users, giving input to the specifications of the unit. A module with a ceramic membrane area of 1 m2 (24 tubes with a length of 90 cm) was made, using a patented concept of an isothermal module. The skid mounted test unit was completed end of June 2000 and first tested at the location of Akzo Nobel Resins in Bergen op Zoom. Dewatering of 5% water in butanol at 75oC gave a flux of 1.8 kg/m2u and 98% water in the permeate, which is far better than the minimum specifications set for the unit in the project proposal. Besides pervaporation the installation can be used for vapour permeation as well. The feed can be fed batch-wise or continuous. The maximum operating temperature is 150oC and the maximum pressure is 10 bar.

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