Neil M. Goldberg

Dry-grind process for fuel ethanol by continuous fermentation and stripping.

Conversion of a high‐solids saccharified corn mash to ethanol by continuous fermentation and stripping was successfully demonstrated in a pilot plant consuming 25 kg of corn per day. A mathematical model based on previous pilot plant results accurately predicts the specific growth rate obtained from these latest results. This model was incorporated into a simulation of a complete dry‐grind corn‐to‐ethanol plant, and the cost of ethanol production was compared with that of a conventional process. The results indicate a savings of

Continuous high-solids corn liquefaction and fermentation with stripping of ethanol

0.03 per gallon of ethanol produced by the stripping process. The savings with stripping result from the capacity to ferment a more concentrated corn mash so there is less water to remove downstream.

Application of the vacuum/steam/vacuum surface intervention process to reduce bacteria on the surface of fruits and vegetables ☆

Removal of ethanol from the fermentor during fermentation can increase productivity and reduce the costs for dewatering the product and coproduct. One approach is to recycle the fermentor contents through a stripping column, where a non-condensable gas removes ethanol to a condenser. Previous research showed that this approach is feasible. Savings of

Kinetics of continuous fermentation and stripping of ethanol

0.03 per gallon were predicted at 34% corn dry solids. Greater savings were predicted at higher concentration. Now the feasibility has been demonstrated at over 40% corn dry solids, using a continuous corn liquefaction system. A pilot plant, that continuously fed corn meal at more than one bushel (25 kg) per day, was operated for 60 consecutive days, continuously converting 95% of starch and producing 88% of the maximum theoretical yield of ethanol. A computer simulation was used to analyze the results. The fermentation and stripping systems were not significantly affected when the CO(2) stripping gas was partially replaced by nitrogen or air, potentially lowering costs associated with the gas recycle loop. It was concluded that previous estimates of potential cost savings are still valid.

Effects of ethanol concentration and stripping temperature on continuous fermentation rate

Abstract A vacuum/steam/vacuum (VSV) surface intervention process has previously been developed for poultry and hot dogs. The process uses a brief exposure to vacuum to remove surface air and water to expose bacteria. After a short treatment with saturated steam (0.1 s), a second vacuum treatment evaporatively cools the surface, resulting in the destruction of bacteria with little or no thermal damage. The VSV surface intervention process has also been applied to fruits and vegetables. Optimization methods were used with cantaloupes, grapefruits, and beets to determine process conditions for steam temperature, steam time, vacuum time, and number of cycles to destroy bacteria with the constraint of little or no thermal damage. Inoculated Listeria innocua was used for the cantaloupe and grapefruit studies and total aerobic plate count (APC) was used for the beet study. Bacteria destruction ranged from 2.5 log cfu/ml APC for beets to almost 4 log L. innocua for grapefruits. The process was successfully applied to other fruits and vegetables such as papayas, mangoes, avocados, kiwis, carrots, cucumbers, and peaches, using the nominal process conditions found with cantaloupes, grapefruits, and beets. Applying the process to bananas, cauliflower, broccoli, and peppers resulted in thermal or mechanical damage. The total process time was 0.5–1.2 s, depending on the number of cycles and the process time per cycle. Assuming that these results with APC and L. innocua are indicative of the treatment of naturally present pathogens, this surface intervention process should ensure that fruits and vegetables suitable for this process will reach the consumer having greatly reduced levels of bacterial contamination.

Control of packed column fouling in the continuous fermentation and stripping of ethanol

A pilot plant consisting of a 30-liter fermenter, and a 10-cm packed column with a blower and condenser to recover ethanol vapors was operated continuously for 185 days. On-line washing of the packing in the column twice weekly with condensed ethanol from the process (approximately 45% v/v) controlled fouling by attached yeast cells. Steady-state glucose consumption rates of up to 800 gh-1, condensed ethanol production rates of up to 26 l/day, and consistently high ethanol yield of approximately 0.50 gg-1 glucose were observed. Data from the pilot plant showed that the primary inhibitory effect of ethanol on the steady-state fermenter performance was to decrease the cell yield, while the specific glucose consumption rate was almost unaffected by ethanol concentrations up to 65 gl-1. A new kinetic model is introduced to represent these effects.

Bio-oil and bio-char production from corn cobs and stover by fast pyrolysis☆

Abstract The operation of a pilot plant consisting of a 14-l fermentor, 10-cm packed column and condenser for continuous fermentation and stripping of ethanol was stable for more than 100 days. The feed consisted of a non-sterile solution of 560 g/l glucose with 100 g/l corn steep water. Fouling of the packing in the column with attached growth of yeast cells was controlled by in situ washing at intervals of 3–6 days. A computer simulation of the pilot plant was developed and used to analyze the data. The productivity of the continuous fermentor varied from 14 g ethanol to 17 g ethanol l−1 h−1. The yield was equal to the maximum theoretically possible: 0.51 g ethanol/g glucose consumed. Results are fit to linear models for the effects of ethanol concentration on specific growth rate and cell yield, and for the effect of stripping temperature on specific growth rate.

Bench-Scale Fluidized-Bed Pyrolysis of Switchgrass for Bio-Oil Production†

By recycling the contents of a 14 L fermentor through a stripping column to continuously remove ethanol and reduce product inhibition, continuous complete conversion of nutrient feed containing 600 g/L glucose was achieved in a small pilot plant. Ethanol was recovered from the carbon dioxide stripping gas in a refrigerated condenser, and the gas was reheated with steam and recycled by a blower. Productivity of ethanol in the fermentor as high as 15.8 g/L/h and condensate production of up to 10 L/day of almost 50% by volume ethanol were maintained for up to 60 days of continuous operation. Weekly washing of the column packing in situ was required to prevent loss of performance caused by attached growth of yeast cells, which restricts the gas flow rate through the stripping column.