Improved ethanol process using pre-fermentation solids removal

(54) Title: PROCESS TO PREPARE A

CHAIN ​​OF BIOMASS PARTICLES CONTAINING STARCH HAVING A SIGNIFICANT PERCENTAGE OF FIBER, FOR PROCESSING IN ETHANOL (30) Unionist Priority: 04/05/2006 su 60/797532 (73) Holder (s): Crown Iron Works Company (72) Inventor ( es): Floyd C. Teeter, Jr.

(74) Attorney (s): Momsen, Leonardos & CIA.

(86) International order: pct US2007068240 of 05/04/2007 (87) International publication: wo 2007 / i3U67de

15/11/2007 (57) Abstract: process to prepare a stream of BIOMASS PARTICLES CONTAINING STARCH WITH A SIGNIFICANT PERCENTAGE OF FIBER, FOR PROCESSING IN ETHANOL Process to prepare a stream of biomass particles containing starch having a significant percentage of fiber for Ethanol processing includes the first stage of: mixing the particle stream with a liquid solvent to dissolve at least a portion of starch in the carbohydrate particle stream to form a carbohydrate suspension stream containing starch dissolved in the liquid solvent. This first step removes a portion of the fiber from the carbohydrate suspension stream. In a second step, the carbohydrate suspension stream is retained in a sedimentation tank to remove an additional portion of the fiber. An improvement to the process is satisfactory for use with corn on the cob or other biomass having a portion of germ containing oil and a non-germ portion comprising mainly carbohydrate and fiber. This improvement includes the step of grinding the corn to particles of a satisfactory size to separate the germ particles from the non-germ particles. The germ particles are processed first to remove the oil and then to remove the carbohydrates.

“PROCESS TO PREPARE A CHAIN ​​OF BIOMASS PARTICLES CONTAINING STARCH WITH A SIGNIFICANT PERCENTAGE OF FIBER, FOR ETHANOL PROCESSING”

This is an international application filed under 35 USC § 363 5 claiming priority under 35 USC § 119 (e) (l), from provisional application Serial No. 60 / 797,532, with a filing date of May 4, 2006.

TECHNICAL FIELD

The present invention relates to the production of grain ethanol and other biomass, in particular corn.

<10 FUNDAMENTALS OF THE INVENTION

One solution to the problem of reliance on foreign sources for energy, particularly for motor vehicle fuel, is to convert biomass into ethanol. Currently available processes use corn or other starch-containing biomass.

For efficiency, the process must convert a large percentage of the biomass into ethanol. The process must take place quickly so that the plant can produce the maximum amount of ethanol per unit time.

Corn is a preferred substance used for the production of ethanol. As is well known, corn seeds comprise a portion of germs and a portion of carbohydrates. The germ portion comprises about 8% of the entire weight. The germ contains about 40% by weight of valuable corn oil, as well as some carbohydrates and fiber. The carbohydrate portion comprises starch, sugar and fiber, and contains almost no oil. On a weight basis, corn seeds make up about 6 to 7% oil, 60 to 70% carbohydrates, 20 to 25% fiber, and 10 to 12% water.

An efficient ethanol process uses enzymes to convert starches in the biomass into sugar before fermentation. The process ferments sugars of any kind to produce CO₂ and ethanol, but it cannot convert starch into ethanol. Bearing in mind that CO₂ is a greenhouse gas, the less CO₂ produced, the better.

In current corn ethanol processes, the corn is ground and mixed with a solvent to form a suspension of ground corn. This suspension comprises both the germ and carbohydrate portions. The enzymes added to the suspension turn the starch into sugar. Fermentation of the sugar in the suspension then produces ethanol. A distillation step separates the ethanol from the suspension. Ethanol is then further refined to · * 10 in a form usable as a fuel for automobiles.

The common ethanol production process has several problems. One of them is the lack of efficiency. This results in the sum of all the energy inputs needed to produce a unitary measure of corn not to be much less than the energy content of the ethanol supplied by that unitary measure. Naturally, the ethanol process produces some useful by-products, such as animal feed and corn oil used in the manufacture of plastics. However, globally, the ethanol production processes in progress are not remarkably efficient.

Second, current ethanol processes produce 20 more contaminant fusel oil in distilled ethanol than is desirable. Fusel oil is an aromatic alcohol that reduces the speed and efficiency of the distillation step. Fusel oil is a by-product of corn oil that reaches the fermentation tank. Consequently, removing as much corn oil as possible from the ground corn particles reduces the concentration of the fusel oil.

BRIEF DESCRIPTION OF THE INVENTION

A process for preparing a stream of biomass particles containing starch having a significant percentage of fiber for processing in ethanol comprises the first step of:

mixing the particle stream with a liquid solvent to dissolve at least a portion of the starch in the carbohydrate particle stream. This forms a stream of carbohydrate particles containing starch dissolved in the liquid solvent, and having a portion of the fiber removed.

The solvent is typically an ethanol-water solution.

In a second step, retaining the carbohydrate suspension stream in a sedimentation tank for a while allows an additional portion of the fiber to sediment to the bottom of the tank. Removing the upper portion of the material in the sedimentation tank forms a corresponding '10% liquid carbohydrate having only a small amount of fiber.

An improvement to the process is suitable for use with corn husk or other biomass having a portion of germ containing oil and a non-germ portion comprising mainly carbohydrates and fiber. This improvement includes the step of grinding the corn into particles of a size allowing the separation of the germ particles from the non-germ particles. The particles are processed first to remove the oil and then to remove the carbohydrates.

In one embodiment, upstream air lifts the 20 lightest non-germ particles in a carbohydrate stream, and allows the germ particles to fall to form a germ stream.

BRIEF DESCRIPTION OF THE INVENTION

Figures 1 and 2 together form a block diagram of an ethanol production facility incorporating the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figures 1 and 2 show an installation that uses a continuous flow process efficiently to produce ethanol and corn oil. The particular installation shown has front and parallel end process steps designed specifically for corn on the cob. When biomass containing non-corn starch is used, the portions of the facility are suitable for converting this non-corn biomass into ethanol with efficiency that may be higher than that currently obtained.

When corn is biomass, corn oil is a valuable by-product of this process. If a biomass other than corn is used, the steps that separate the germ portions from the non-germ of the individual grains can be omitted, and this processes the germ portion.

Figure 1 shows the components of the installation that perform the initial processing to partially separate the corn germ from the non-germ, or the portion of starch and sugar (carbohydrate), and that process the corn starch and sugar components into ear. Figure 2 shows the installation components that extract oil from the corn germ portion and process the remaining components from the germ portion for ethanol production.

Front End Corn Processing

In Figure 1, loose grain corn is stored in a receptacle 32. Grain corn flows in a direct current to a mill or grinder 36. Ideally, mill 36 grinds grain corn to a fineness that creates particles individuals that are or essentially all germs or are non-germs. As mentioned, the germ is initially about 8% of the whole grain. Particles containing mainly grain germ material have a specific gravity slightly higher than that of non-germ particles.

Preferably the individual particles exiting the mill 36 have a maximum dimension in the range of 0.3 to 0.6 mm, and a minimum dimensional range of perhaps half that range. This corresponds to a roller mill whose rollers are adjusted to a spacing of 0.2 to 0.4 mm.

Ground maize forms a stream of particles, hereinafter “dry maize flour stream”, which is released to a mechanical separator 39. In the version shown, separator 39 uses different specific gravities of the particles in the dry maize flour stream to separate those with higher specific gravity containing the germ, from those comprising only carbohydrate material. Preferably, separator 39 has a vacuum design that injects air into an air inlet 38 near the bottom of separator 39. Air flows upward through the corn particles that fall on top and through separator 39.

Another version of mechanical separation relies on the characteristic of ground corn in which the particles in the germ portion are slightly larger than the non-germ portions.

As for the corn flour particles in the mentioned range, the upward air velocity can be in the range of 50 to 150 fpm. A stream of cornmeal having particles at the upper end of the preferred size range, will require slightly higher air speed. Smaller particles will need less air velocity. Experimentation suggests that very small particles will not allow the germ and non-germ particles to separate efficiently.

Separator 39 divides the maize flour stream into a carbohydrate stream and a germ stream. The carbohydrate stream leaves the upper part of the separator 39 and circulates through a first duct or tube 15 to a particle precipitator 13. The corn germ descends down through separator 39, flowing from the bottom of separator 39 like a stream of germs to a second duct or tube 37, and to an oil extractor 90, see Figure 2. Connector element B symbolizes the continuation of duct 37 from Figure 1 to Figure 2.

The separation of the germ and carbohydrate portions of the maize flour stream in separator 39 is far from perfect. Typically, separator 39 approximately doubles the concentration of germ in the germ stream around 15 to 20% against approximately 8% by weight in the cornmeal stream. The pure germ particles can comprise around 40% corn oil, so that the concentration of corn oil in the germ stream can be approximately 6 to 8%. On the other hand, almost no germ particles circulate in the carbohydrate stream. Consequently, little or no corn oil is present in the carbohydrate stream.

Carbohydrate Stream Processing

The speed of the air circulating through the duct 15 and carrying a greater proportion of reductions when it enters the precipitator 13. The particles suspended in the moving air fall towards the bottom of the precipitator 13 when the air becomes slower inside the precipitator 13 . In one version, a fan 17 connected over precipitator 13 pulls air through a precipitator filter 13.0 vacuum that fan 17 creates in precipitator 13 is propagated to separator 39 through duct 15, causing air to flow to through the air inlet 38.

The carbohydrate stream falls within the inlet 65 of a first auger-type carbohydrate extractor 60. The processing of the carbohydrate stream, when it enters the extractor 60, is suitable for a wide range of fermentable biomass. Thus, sugar cane, beets, and other sources of starch or sugar, can be ground to an appropriate particle size and supplied at the entrance 65.

Inlet 65 uses a auger to force the carbohydrate stream into a chamber 56 of extractor 60 maintained at relatively high pressure, perhaps 150 to 350 psi (1.0 MPa to 2.4 MPa). Inlet 65 includes a seal or seal that retains pressure within chamber 56. A motor slowly rotates the auger 60 to move the carbohydrate stream towards the outlet at the right end of chamber 56.

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A pump 23 releases a carbohydrate solvent, preferably an ethanol-water solution (also called a polar solvent), from a supply tank 26 maintained at a relatively high pressure, perhaps 3000 to 5000 psi (20.7 34.5 MPa MPa), for the extractor chamber 56. The solvent sprays in the carbohydrate stream inside chamber 56, and dissolves the carbohydrates in the carbohydrate stream to produce a liquid stream of carbohydrates in the form of a fine suspension flowing through a choke valve 68 to a sedimentation tank 71. A preferred weight ratio of the index of ^J The solvent flow rate for the flow rate of the carbohydrate stream within the chamber 56 is approximately 2: 1, but ratios in the range of approximately 3: 2 to 3: 1 may also serve adequately.

The throttle valve 68 reduces to approximately atmospheric the pressure of the liquid carbohydrate stream flowing from the extractor 15 60 to the sedimentation tank 71. The liquid carbohydrate stream flowing to the tank 71 has a substantial amount of particulate material containing mainly fiber.

The sedimentation tank 71 can be of any of the dredge types that slowly agitate and move the sedimentation solids to one end of the tank 71. The tank 71 has a port near the top, through which the fluid is drained or decanted as a net stream of carbohydrate flowing to an ethanol extractor 74.

The solids remaining in the chamber 56 of the extractor 60 flow to a desolventizing unit 59 that vaporizes the ethanol solvent25 water. The solvent vapors flow to a condenser 42, which condenses the solvent vapors. A throttle valve 57 forming part of the condenser 42 reduces the pressure of the solvent vapors to approximately atmospheric in the desolventizing unit 59. The pump 53 transports the condensed solvent to a processor 29. Pump 29 must produce adequate pressure to force liquid solvent to the bottom of a tank 26, which may have solvent resting 30 m. or more. Processor 29 represents components that rebalance the liquid solvent of water-ethanol and supplies it to tank 26 for reuse.

The solids flow from the desolventizing unit 59 for further processing in animal feed. Processing to this point, removed most of the solvent from the solids.

In the sedimentation tank 71, much of the particulate material in the liquid carbohydrate stream settles at the bottom, where it flows to -10 out through the port near the bottom of the tank 71 like a particle stream to the desolventizing unit 72.

The desolventizing unit 72 removes ethanol from the particle stream, which flows to condenser 48 and pump 51. From pump 51, condensed ethanol flows to processor 29 for reuse. When the composition of the particle stream provided by the sedimentation tank 71 is different from that provided by the desolventizing unit 59, the processing for the sedimentation particles in the desolventizing unit 72 differs from that for the solids in the desolventizing unit 59. When the composition of the solids that leaving the tank 20 71 is similar to those leaving the extractor 60, the outlet of the tank 71 can flow to the desolventizing unit 59.

Extractor 74 vaporizes most of the ethanol remaining in the net carbohydrate stream. The solvent vapors flow through a pipe or duct, as connector element A indicates, to a condenser 25 45 that condenses the ethanol vapors. The pump 53 takes the condensed ethanol vapors from the condenser 45 to the inlet pressure of the element 29, and supplies the condensed ethanol vapors to the element 29. Extractor 74 may comprise various stages of ethanol removal using distillation and other means as well. The industry is well aware of this ethanol extraction technology.

At this stage, the net carbohydrate stream carries very little solid material (fibers). The net stream of carbohydrates circulates to a 77 digester where the enzymes mix with the net stream of 5 carbohydrates to convert the starches into the net stream of carbohydrates into sugar. The fermentation processes currently used cannot easily convert starch into ethanol. CO₂ it is a normal by-product of the fermentation process, and is supplied by the plumbing indicated by the connector element C to the oil removal portion of the process.

Digester 77, fermenter 83 and ethanol extractor 80 are conventional devices. However, removing almost all of the fiber from the liquid carbohydrate stream before entering digester 77 as extractor 60 and settling tank 71o does, substantially improves the efficiency of the process.

The ethanol from extractor 80 is stored in a tank 86 for distribution to users. Some ethanol in tank 86 flows to processor 29 through a pump 88 to replace the ethanol lost in the extraction process. A suitable feedback system can control the amount of replacement ethanol delivered to the processor 29.

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Oil Stream Processing

The mechanical separation of the germ and carbohydrate by the separator 39 produces the germ current loaded in the duct 37. The connector element B symbolizes the flow of the germ current to an extractor 90 operating in a dual solvent mode.

The oil content of the germ stream is dissolved by the

CO₂ liquid supplied by the CO tank₂ 96. Preferably, CO₂ in tank 96 is that which fermentor 83 provides as a natural by-product of fermentation. Pump 93 receives CO₂ fermentor 83 through connector element C and compress this CO₂ gaseous to liquefy it. A heat exchanger can be combined with pump 93 or tank 96 to cool CO₂ liquid, or even to allow liquefaction to occur.

Pump 99 raises CO pressure₂ liquid entering chamber 105 to a range of approximately 4000 to 8500 psi (27.6 to 58.65 5 MPa). CO₂ liquid enters an oil extractor 90 at the upstream end of an extraction chamber 105.

Structurally, the extractor 90 can be very similar to the extractor 60 of carbohydrates. However, extractor 90 operates in a dual mode that removes both oil and carbohydrates from the germ stream.

Extractor 90 has an inlet 102 that receives the germ current and forces this germ current into an extraction chamber 105. Inlet 102 includes an air seal or closure, such as the auger shown, that retains the pressure inside chambers 105 and 107. Extractor 90 differs from extractor 60 by tail of CO₂ pressure switch on the upstream end of chamber 105.

CO₂ liquid entering chamber 105 dissolves corn oil in the material of the germ stream inside chamber 105. CO₂liquid with dissolved oil flows from chamber 105 through a throttle valve 112 for conventional processing and 20 storage elements. These elements remove CO₂, perhaps by blast removal of CO₂, and refine the oil for use in food, plastics and other industrial purposes.

The germ stream then flows into the downstream section of chamber 105 to remove many of the carbohydrate materials present in the germ stream. The downstream section of chamber 105 functions as an extractor in a very similar way to that of extractor 60. An ethanol-water solution enters chamber 105 at a point midway and mixes with the germ stream.

The outlet from the downstream end of chamber 105 is very similar to that of extractor 60. The solids flow through the choke valve 108 to a desolventizing unit 148 similar to unit 59. The ethanol in these solids is vaporized and flows into condenser 110 and pump 119. Pump 119 pumps the condensed ethanol into a processor 128 and a storage tank 135 for reuse. Solids flow from unit 148 for further processing. It is easily possible that the ethanol vapors in the extractor 90 have a composition that allows the desolventizing unit 59 to process them, in which case the desolventizing unit 148, the condensing unit 110 and the pump 119 '10 become unnecessary.

A liquid stream of carbohydrate flows from chamber 105 through a throttle valve 144 to a second sedimentation tank 141 similar to tank 71. The liquid stream from chamber 105 has a substantial percentage of carbohydrates and solids. The sedimentation tank 141 is very similar to the sedimentation tank 71, and operates with very similar parameters. The tank 141 separates by sedimentation much of the solid material in the liquid stream of the extractor 90.

The solids that separate by sedimentation in tank 141 flow from the bottom of tank 141 to the desolventizing unit 152. The ethanol in the solids stream is vaporized and removed by the desolventizing unit 152, condensed by condenser 155 and pumped upward by pump 158 under pressure input to processor 128.

A liquid comprising mainly carbohydrates flows from above the material in the sedimentation tank 141 to an ethanol extractor 138. Extractor 138 is similar to extractor 74 and removes most of the ethanol remaining in the liquid carbohydrate stream. The removed ethanol flows through connector element D to condenser 115 and pump 121, for reuse through processor 128.

The carbohydrate stream flows from extractor 138 through connector element E to digester 77 in Figure 1. In this way, the carbohydrate content of the germ portion can be used to produce ethanol without the undesirable effects of fusel oil inside the fermenter 83 In addition, most of the fiber will have been removed, which helps with efficiency 5 for the fermentation process.