Edible alcohol is primarily produced using starchy raw materials such as tubers, grains, and corn. Under the action of microorganisms, the starch is hydrolyzed into glucose, which is then further fermented to produce alcohol. Additionally, alcohol is produced through the fermentation of molasses and the fermentation of waste liquor from sulfite pulp. The vent gas generated during the alcohol fermentation process typically contains a carbon dioxide concentration of over 95% in the raw gas exiting the fermenter, with other impurities including alcohols, aldehydes, esters, and sulfides.

Existing CO₂ recovery projects for alcohol vent gas primarily employ water washing and double-column distillation processes. The water washing method utilizes the mutual solubility between water and alcohol; through equipment such as spray towers or packed towers, water is brought into contact with the alcohol fermentation vent gas to absorb impurities like alcohols, thereby reducing the concentration of the exhaust gas. The washed water is then recycled to the dilute alcohol water unit. This method effectively removes most water-soluble impurities, such as alcohols. However, it struggles to remove sulfur, aldehydes, esters, and benzene. Furthermore, the process requires multi-stage scrubbing, resulting in a complex workflow, numerous pieces of equipment, and significant capital investment in equipment and piping.

Dual-tower distillation primarily separates heavy and light fractions. Practical experience has shown that it is difficult to achieve food-grade quality standards with this method; it can only meet industrial-grade standards. To meet food-grade quality standards, additional process methods must be employed.

In our alcohol tail gas recovery project, we have adopted a new process route that combines desulfurization, catalytic oxidation combustion (for removing alcohols and aldehydes), and multi-stage liquid distillation: After pressurizing and desulfurizing the feed gas, a catalyst is used to promote the complete combustion of the alcohol tail gas with oxygen in the air at a lower temperature, converting organic compounds into carbon dioxide and water vapor. All hydrocarbons can be completely removed during the catalytic oxidation reaction to meet high-purity standards. This approach significantly simplifies the original process flow, reduces the challenges of high water consumption and wastewater discharge associated with the previous technology, and avoids the need for extensive equipment and complex processes. Our company’s new process method significantly reduces investment in equipment and piping, requires minimal floor space, is easy to maintain, and produces high-quality products, including high-purity carbon dioxide and food-grade carbon dioxide.

This technology is a patented and proprietary technology of Hangzhou Kuai Kai. Infringement will be prosecuted.