Recently, the 2.2 million ton/year PTA unit CTA solvent exchange unit, which was independently developed and manufactured by Tianhua Institute of Chemical Machinery & Automation (Tianhua Institute), passed the performance acceptance test of the customer, indicating that Tianhua Institute has made success in independent development, manufacturing and industrial application of China’s first CTA solvent exchange unit, its equipment technologies have reached a world leading level and it has the capability of large-scale industrial application and promotion.
The solvent exchange unit at the site of application
According to the results of the field test data, all process and mechanical indexes of the unit have reached or are even better than the required value in the contract under the condition of 110% load. Especially, for the washing efficiency, a core technical index, the contract requires that the content of acetic acid in the filter cake is less than or equal to 4.5kg/t-CTA on a dry basis, while the actual operation value of acetic acid in the cake is 2kg/t-CTA on a dry basis, completely better than other similar devices.
CTA solvent exchange technology, as the core and latest technology of PTA device, is a milestone in the development of PTA technology, and for this it is very popular amongst all PTA manufacturers. Tianhua Institute started its research on and development of relevant solvent exchange technologies as early as ten years ago, and has now mastered the technology exclusively after years of efforts.
The technology, by adding process water to a specially-designed CTA solvent switch, filters and washes CTA slurry containing acetic acid, turns the slurry into CTA filter cake, and then makes it pass through the pulp refining unit. In this way, the complex filtering, drying, pneumatic conveying and storage processes of the complicated PTA oxidation unit are simplified into "solvent exchange unit". The technology can greatly shorten the process of the PTA oxidation unit, reduce the investment of equipment. In addition, the technology features advantages of small footprint and convenient operation.
At present, Tianhua Institute has applied for 20 Chinese patents and five foreign patents, of which 14 have been granted, including five invention patents.