Method for producing fuel ethanol based on high-quality DDGS product

Abstract

The invention belongs to the technical field of biomass energy production, and discloses a method for producing fuel ethanol based on a high-quality DDGS product. A mash preparation unit and a rectification unit are used, a second rectification tower waste mash of the rectification unit is delivered to a waste mash treatment unit, solid substances in the waste mash are recycled, and the DDGS product is produced; secondary rectification tower top steam is heated and pressurized through a compressor, the steam-liquid equilibrium temperature of the obtained pressurized reflux steam of the secondary rectification tower is higher than the operating temperature of a crude tower kettle, and the pressurized reflux steam is sent to a reboiler of a crude tower as a heating medium; the secondary rectification tower top steam is heated and pressurized through the compressor to obtain secondary rectification tower pressurized adsorption steam which is superheated steam, preheating operation is notrequired, and the superheated steam is directly delivered to an adsorber A or an adsorber B of an adsorption unit for adsorption dehydration operation to obtain a fuel ethanol product. By the technical scheme, the industrial problems of high heating temperature of solid-containing materials such as fermented mash and waste mash, easiness in scarring of equipment such as the reboiler and a tray, unstable production, influence on DDGS product quality and the like in an existing main fuel ethanol production process are solved.

Description

technical field [0001] The invention belongs to the technical field of biomass energy production, and in particular relates to a method for producing fuel ethanol based on high-quality DDGS products. Raw materials such as corn, wheat, rice, cassava, sorghum and sweet potato are used, and the production process includes production units such as mash preparation, rectification, adsorption dehydration and waste mash treatment. The disclosed technical solution is aimed at the multi-stage thermally coupled rectification process adopted in the refining process of the current mainstream production process of fuel ethanol, resulting in high heating temperature of waste mash and other solid-containing materials, and the reboiler and trays of the rectification production device are prone to condensation. Scars, unstable production, subsequent waste mash recovery of solid phases to produce DDGS products will turn black, affecting the quality of DDGS products and other industry problems. ...

AI Technical Summary

Problems solved by technology

[0004] The technical limitations of the current mainstream fuel ethanol production technology: In order to realize the multi-stage multi-effect coupling utilization of the heat of each rectification tower or equipment in the refining unit, the operating pressure of the recovery tower and rectification tower is artificially increased to achieve the realization of heat The energy level of multi-effect and multi-stage utilization, because the alcohol content of the top of the crude distillation tower is generally designed to be 50-70%, and the reasonable condensation temperature of the top steam is ≥ 45°C, only in this way can the top condenser be used under outdoor temperature conditions The cooling of the conventional circulating cooling water prepared under the following conditions is only feasible and economical in industrial production, and when the minimum operating temperature of the overhead steam of the crude distillation tower is 45°C, the corresponding top operating pressure of the crude distillation tower is ≤- 0.08MPa (there is no special description in this article, the operating pressure is gauge pressure), and the corresponding normal operating temperature of the crude distillation column tank is ≥78°C. The condensing temperature of the distillation tower top steam needs to be ≥80°C, resulting in the normal operating temperature of the corresponding rectification column tower kettle being ≥110°C, and the solid waste mash in the distillation tower kettle is processed under the operating condition of a temperature of ≥110°C ; The chemical characteristics and production practice of DDGS feed all show that when the solid materials such as fermented mash and waste mash are processed under the condition of operating temperature ≥ 100 ℃, the reboiler and tower for processing solid materials such as fermented mash and waste mash The plate is easy to block, and the waste mash discharged from the rectification unit is sent to the waste mash treatment unit to produce DDGS products with high color number, serious carbonization of solid phase, and large loss of nutrients, which cannot meet the minimum requirements of DDGS feed products (See GB / T25866-2010), which can only be sold at a reduced price, which affects the overall economic benefits of fuel ethanol production enterprises. It is necessary to control the treatment temperature of solid materials such as fermented mash and waste mash to ≤100°C to improve the quality of DDGS products; When the operating temperature of the solid waste mash in the distillation tower bottom is required to be ≤ 100°C, the corresponding condensation temperature of the overhead vapor of the distillation tower will be lower than the normal operating temperature of the crude distillation tower bottom, and the rectification tower cannot be used The top material steam heats the crude distillation column reboiler, and the steam consumption of the rectification unit will increase significantly

The steam compressors used in the MVR system are mostly centrifugal steam compressors and Roots compressors. Among them, single-stage compressors have the highest energy consumption efficiency. The single-stage compression ratio of the unit is usually ≤2.4, and there is a certain limit to the increase in temperature rise energy level. , such as 1 ton of secondary water vapor at 70-80°C is usually raised to 90-100°C through single-stage compression of the unit, and the power consumption is about 30-40kw. According to the electricity price of 0.75 yuan / kwh, the operating cost is increased by 22.5-30 yuan, usually The production cost of fresh steam is ≥100 yuan / ton, and the outsourcing price is usually more than 200 yuan

If the energy level of the material vapor is too low, multi-stage compressors are used to increase the temperature and increase the energy level. The energy consumption in the process of boosting and heating is high, and it is not economical to recover the latent heat of the low-energy level material vapor. Reasonable, the energy-saving effect is not obvious, it is necessary to comprehensively consider the benefits brought about by the improvement of DDGS product quality

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