我国燃料乙醇生产技术的现状与展望

概述了目前国内外燃料乙醇产业现状.结合我国中粮生化能源(肇东)有限公司燃料乙醇装置,重点介绍了我国目前的燃料乙醇生产工艺技术水平、特点以及与国外的差距.本文从提高燃料乙醇生产技术水平、降低生产成本、寻找廉价非粮原料和开发新生产工艺等几个方面,对燃料乙醇生产技术的发展作了展望.     

我国燃料乙醇生产技术的现状与展望

概述了目前国内外燃料乙醇产业现状。结合我国中粮生化能源(肇东)有限公司燃料乙醇装置,重点介绍了我国目前的燃料乙醇生产工艺技术水平、特点以及与国外的差距。本文从提高燃料乙醇生产技术水平、降低生产成本、寻找廉价非粮原料和开发新生产工艺等几个方面,对燃料乙醇生产技术的发展作了展望。     

秸秆生产乙醇预处理关键技术

乙醇是一种很有希望替代有限石油的燃料.目前燃料乙醇已在我国部分省市得到应用.我国目前燃料乙醇生产的主要原料是陈化粮,但我国陈化粮可用于燃料乙醇生产的量十分有限.真正可大量转化乙醇的应是纤维质材料.纤维质材料转化乙醇的挑战性问题是产量偏低、成本偏高.纤维质材料的预处理是转化乙醇过程中的关键步骤,该步骤的优化可明显提高纤维素的水解率,进而降低乙醇的生产成本.本文总结了纤维质材料预处理的各种方法,对各种方法的优缺点进行了综述和分析,并对生物质预处理技术发展的前景进行了展望.     

秸秆发酵燃料乙醇关键问题及其进展

利用木质纤维素原料生产燃料乙醇是国际公认的难题.本文从秸秆原料组分不均一性出发,分析了秸秆难以高值化原因;进一步分析了秸秆酶解发酵燃料乙醇的关键问题,介绍了有关秸秆原料预处理、纤维素酶生产、秸秆酶解发酵乙醇和产业化示范工程等的进展.秸秆酶解发酵燃料乙醇产业化示范工程具有自主知识产权,为实现我国秸秆转化燃料乙醇的规模化、产业化、低成本生产奠定了基础.     

秸秆发酵燃料乙醇关键问题及其进展

利用木质纤维素原料生产燃料乙醇是国际公认的难题.本文从秸秆原料组分不均一性出发,分析了秸秆难以高值化原因;进一步分析了秸秆酶解发酵燃料乙醇的关键问题,介绍了有关秸秆原料预处理、纤维素酶生产、秸秆酶解发酵乙醇和产业化示范工程等的进展.秸秆酶解发酵燃料乙醇产业化示范工程具有自主知识产权,为实现我国秸秆转化燃料乙醇的规模化、产业化、低成本生产奠定了基础.     

秸秆生产乙醇预处理关键技术

乙醇是一种很有希望替代有限石油的燃料。目前燃料乙醇已在我国部分省市得到应用。我国目前燃料乙醇生产的主要原料是陈化粮,但我国陈化粮可用于燃料乙醇生产的量十分有限。真正可大量转化乙醇的应是纤维质材料。纤维质材料转化乙醇的挑战性问题是产量偏低、成本偏高。纤维质材料的预处理是转化乙醇过程中的关键步骤,该步骤的优化可明显提高纤维素的水解率,进而降低乙醇的生产成本。本文总结了纤维质材料预处理的各种方法,对各种方法的优缺点进行了综述和分析,并对生物质预处理技术发展的前景进行了展望。     

纤维素制取乙醇技术

以纤维素为原料生产燃料乙醇由于其原料来源广泛及环保效益良好而被认为是最有前景的生产燃料乙醇的方法之一.以纤维素为原料生产乙醇主要包括水解和发酵两个转化过程.本文介绍了纤维素生产燃料乙醇的原理及工艺过程,同时讨论了各工艺过程需要解决的关键技术问题,分析了过程的经济性,最后介绍了国内外的应用现状,展望了纤维素生产燃料乙醇的产业化前景.     

秸秆生产乙醇预处理关键技术

乙醇是一种很有希望替代有限石油的燃料.目前燃料乙醇已在我国部分省市得到应用.我国目前燃料乙醇生产的主要原料是陈化粮,但我国陈化粮可用于燃料乙醇生产的量十分有限.真正可大量转化乙醇的应是纤维质材料.纤维质材料转化乙醇的挑战性问题是产量偏低、成本偏高.纤维质材料的预处理是转化乙醇过程中的关键步骤,该步骤的优化可明显提高纤维素的水解率,进而降低乙醇的生产成本.本文总结了纤维质材料预处理的各种方法,对各种方法的优缺点进行了综述和分析,并对生物质预处理技术发展的前景进行了展望.     

纤维素制取乙醇技术

以纤维素为原料生产燃料乙醇由于其原料来源广泛及环保效益良好而被认为是最有前景的生产燃料乙醇的方法之一.以纤维素为原料生产乙醇主要包括水解和发酵两个转化过程.本文介绍了纤维素生产燃料乙醇的原理及工艺过程,同时讨论了各工艺过程需要解决的关键技术问题,分析了过程的经济性,最后介绍了国内外的应用现状,展望了纤维素生产燃料乙醇的产业化前景.     

秸秆发酵燃料乙醇关键问题及其进展

利用木质纤维素原料生产燃料乙醇是国际公认的难题。本文从秸秆原料组分不均一性出发,分析了秸秆难以高值化原因;进一步分析了秸秆酶解发酵燃料乙醇的关键问题,介绍了有关秸秆原料预处理、纤维素酶生产、秸秆酶解发酵乙醇和产业化示范工程等的进展。秸秆酶解发酵燃料乙醇产业化示范工程具有自主知识产权,为实现我国秸秆转化燃料乙醇的规模化、产业化、低成本生产奠定了基础。     

The future of coproducts from corn processing

Increased demand for ethanol as a fuel additive has resulted in dramatic growth in ethanol production. Ethanol is produced from corn by either wet milling or dry-grind processing. In wet milling, the corn kernel is fractionated into different components, resulting in several coproducts. Wet-milling plants are capital intensive because of equipment requirements; they produce large volumes of ethanol and are corporate owned. In dry-grind processing, the corn kernel is not fractionated and only one coproduct, distillers’ dried grains with solubles (DDGS), is generated. Dry-grind plants require less equipment and capital than wet mills. They generate smaller volumes of ethanol, are producer owned, and add direct benefits to rural economies. Most of the increase in ethanol production during the past decade is attributed to growth in the dry-grind industry. The marketing of coproducts provides income to offset processing costs. For dry-grind plants, this is especially important, because only one coproduct is available. Several issues could affect DDGS marketing. The increasing volume of DDGS accompanying ethanol production could reduce market value; high phosphorous content could limit the use of DDGS, because of animal waste disposal issues. Water removal is a costly processing step and affects the economics of ethanol processing. Technologies to remove germ and fiber from DDGS could produce a new coproduct suitable for feeding to nonruminants; this would expand the markets for DDGS. Reducing phosphorus in DDGS would sustain markets for conventional DDGS. The development of more efficient methods of water removal would increase the efficiency of ethanol processing and reduce the costs of processing. New technologies could contribute to greater stability of dry-grind plants.     

Fermentation and costs of fuel ethanol from corn with quick-germ process

The Quick-Germ process developed at the University of Illinois at Urbana-Champaign is a way to obtain corn oil, but with lower capital costs than the traditional wet-milling process. Quick-Germ has the potential to increase the coproduct credits and profitability of the existing dry-grind fuel ethanol process, but the fermentability of the corn remaining after oil recovery has not been tested. Therefore, a series of pilot scale (50 L) fermentations was carefully controlled and monitored with unique methods for standard inoculation and automatic sampling. It was found that the concentration of suspended solids was significantly reduced in the Quick-Germ fermentations. When compared at the same concentration of fermentable sugars, the fermentation rate and yield were not statistically different from controls. When Quick-Germ was integrated into a state-of-the-art dry-grind fuel ethanol process, computer simulation and cost models indicated savings of approx $0.01/L of ethanol ($0.04/gal) with the Quick-Germ process. Additional savings associated with the lower suspended solids could not be quantified and were not included. However, the savings are sensitive to the price of corn oil. Mention of brand or firm name does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.     

Fuel ethanol production from corn fiber current status and technical prospects

Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed for use in pretreated corn fiber saccharification. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

中国纤维素乙醇技术的研究进展

中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用.尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本.近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2-1.5美元/加仑.其中,每吨生物质约44美元.因此,目前乙醇掺汽油具有十分强的市场竞争力.已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂.尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高.进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料.     

Fermentation of “Quick Fiber” produced from a modified corn-milling process into ethanol and recovery of corn fiber oil

Approximately 9% of the 9.7 billion bushels of corn harvested in the United States was used for fuel ethanol production in 2002, half of which was prepared for fermentation by dry grinding. The University of Illinois has developed a modified dry grind process that allows recovery of the fiber fractions prior to fermentation. We report here on conversion of this fiber (Quick Fiber [QF]) to ethanol. QF was analyzed and found to contain 32%wt glucans and 65%wt total carbohydrates. QF was pretreated with dilute acid and converted into ethanol using either ethanologenic Escherichia coli strain FBR5 or Saccharomyces cerevisiae. For the bacterial fermentation the liquid fraction was fermented, and for the yeast fermentation both liquid and solids were fermented. For the bacterial fermentation, the final ethanol concentration was 30 g/L, a yield of 0.44 g ethanol/g of sugar(s) initially present in the hydrolysate, which is 85% of the theoretical yield. The ethanol yield with yeast was 0.096 gal/bu of processed corn assuming a QF yield of 3.04 lb/bu. The residuals from the fermentations were also evaluated as a source of corn fiber oil, which has value as a nutraceutical. Corn fiber oil yields were 8.28%wt for solids recovered following prtetreatment.     

Element concentrations of dry-grind corn-processing streams

The dry-grind corn process is one of two technologies used to convert corn into ethanol. In his process, all kernel components are processed through several sequential steps, including fermentation. Only one coproduct (distillers’ dried grains with solubles [DDGS]) is available for marketing. DDGS provide income to offset costs of processing; issues that affect marketing have implications in the economic viability of dry-grind plants. Two issues relate to elements in DDGS: high concentrations and excessive variation. Data on element concentrations in dry-grind processing streams could be helpful in addressing these concerns. The objective of this study was to determine element concentrations in primary process streams from dry-grind plants. Samples of corn, ground corn, beer, wet grains, syrup, and DDGS were obtained from nine dry-grind plants, and element concentrations were determinined. The concentrations of most elements in corn were not different among processing plants and were similar to published data. However, for the processing streams, there were differences in several element concentrations among processing plants. The concentrations of most elements in beer were about three times those of corn, due to the disappearance of starch during fermentation. Syrup had the highest element concentrations. Variations in element contents of DDGS and parent streams were due to processing conditions and not corn. Appropriate processing of thin stillage (the parent stream of syrup) could reduce the element content of DDGS.     

Assessment of waxy and non-waxy corn and wheat cultivars as starch substrates for ethanol fermentation

The amylose/amylopectin ratio in cereal substrates is one of the parameters affecting starch hydrolysis and fermentation process. Waxy (less than 1 mass % of amylose) starch seems to be suitable for improving the fuel ethanol production. The main aim of this paper was to characterize the fermentation performance of corn and wheat waxy and non-waxy cultivars in terms of simultaneous saccharification and fermentation (SSF) as well as of the separated hydrolysis and fermentation (SHF) type. Two corn (waxy and non-waxy) and two wheat (waxy and non-waxy) cultivars were used for the comparison applying separate enzymatic hydrolysis and fermentation. In the SHF process, the glucose content was higher after saccharification in the waxy corn and wheat compared to that in non-waxy corn and wheat. In the SSF of waxy varieties, the glucose content after the pre-saccharification was also higher than in the non-waxy ones. Although the starch content did not vary significantly, differences in the glucose content after saccharification were observed. The ethanol yield obtained after the distillation of mash varied from 229.2–262.3 L per ton for the SHF fermentation, while it was in the range of 311.5–347.9 L per ton for the SSF process.