Solvent recovery method for supercritical CO2 drying in silicon-based aerogel production

Abstract

The invention discloses a solvent recovery method for supercritical CO2 drying in silicon-based aerogel production. A device involved in the recovery method mainly comprises a supercritical extractionkettle, a separation kettle, a multi-stage flash tank, a multi-stage compressor and a rectifying tower, and process equipment and a control system are simple and easy to realize. According to the solvent recovery method, the gas phase of the separation kettle is condensed to separate a solvent, a liquid phase solvent of the separation kettle is subjected to multi-stage flash evaporation compression, and finally rectification is performed, so that high-purity, high-quality and high-yield recovery of the solvent is realized, the treatment capacity of the compressor is more reasonable and accurate, and the purposes of saving energy consumption and reducing production investment cost are achieved. And moreover, wastewater discharge is reduced, and environmental friendliness is realized.

Description

technical field [0001] The present invention relates to a kind of supercritical CO 2 Dry solvent recovery method. Background technique [0002] In the preparation of silicon-based aerogels, the currently known supercritical drying process roughly follows the process: figure 1 Shown is: liquid carbon dioxide is stored in the intermediate storage tank 1 (4-7MPa), pressurized by the booster pump 2 to reach the pressure required by the process (8-30MPa), and then heated to the required temperature (31-30MPa) by the heater 3 80° C.) to make it reach the supercritical state, and pass it into the airgel supercritical extraction kettle 4, where the airgel felt fully infiltrated by the solvent is placed in advance. The supercritical carbon dioxide is in full contact with the airgel blanket, replacing and fully occupying all the voids of the airgel, and then the supercritical carbon dioxide fluid dissolved in the solvent flows out from the extraction kettle, and after being decompre...

AI Technical Summary

Problems solved by technology

The problem in this process is that if the flash pressure is low, although the carbon dioxide and solvent can be separated more thoroughly, the operation of reducing a large amount of carbon dioxide gas from high pressure to low pressure and then recompressing and pressurizing back to high pressure will cause the compressor 20 to process Excessive quantity not only wastes energy, but also increases the difficulty of equipment manufacturing, increases equipment investment, and increases costs

However, if the flash pressure is high, the amount of carbon dioxide remaining in the solvent will increase, and will be discharged together with the waste solvent, and accumulated in multiple batches of operations, resulting in a large amount of carbon dioxide raw material loss and increasing the cost of production raw materials

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