CN204174468U - equipment for heating feed - Google Patents

Abstract

The utility model provides an equipment of heating feed contains: the elongated chamber (140) is at least partially cylindrical. The chamber comprises: (a) an inlet to receive feedstock and an outlet to discharge heated feedstock; (b) a rotatable shaft (142) coaxially mounted in the chamber; and (c) means (139, 138A) for heating the comminuted feedstock particles as they are transported through the chamber. The rotatable shaft includes: (i) an inlet portion comprising an auger (145) for transporting and breaking up the feedstock at the inlet region of the chamber, wherein the auger comprises a pocket or groove formed therearound for breaking up the feedstock. The rotatable shaft further comprises a plurality of shredding elements (143) mounted on at least a middle portion of the rotatable shaft for shredding the feedstock. The reducing elements project outwardly from the shaft and are inclined at an angle offset from a line drawn transverse to the rotatable shaft.

Description

equipment for heating feed

technical field

The utility model provides an improved equipment for heating and feeding materials.

Background technique

There is growing interest in utilizing lignocellulosic feedstocks such as wheat straw, corn stover and switchgrass to produce fuel ethanol or other fermentation products.

One approach to producing a fermentation product, such as ethanol, from a lignocellulosic feedstock is to perform a pretreatment followed by enzymatic hydrolysis of the cellulase to glucose. Pretreatment essentially breaks down the fibrous structure of the lignocellulosic feedstock and increases the surface area of the feedstock to make it accessible to lignocellulosic enzymes. Pretreatment can be performed such that a high degree of hydrolysis of xylan occurs and only a small amount of cellulose is converted to glucose. Cellulose is hydrolyzed to glucose in a subsequent step using lignocellulosic enzymes. Other pretreatment processes, such as certain alkaline pretreatments, do not hydrolyze xylan or result in limited hydrolysis of xylan. In addition, more severe chemical treatments such as concentrated acid hydrolysis can be used to hydrolyze both xylan and cellulose.

Regardless of the method of producing fermentable sugars, water is typically added to the incoming feedstock to form a slurry to facilitate the transportation and mechanical processing of the cellulosic feedstock. The slurry consists of lignocellulosic feedstock pieces or pellets in water. In many of the lignocellulosic conversion processes described in the prior art to produce fermentable sugars, the solids content measured as undissolved solids (referred to herein as "UDS") is between 5 wt% and 12 wt%.

However, for more economical lignocellulosic conversion processes, it is desirable that they operate at lower water contents. Processing feedstocks containing high solids content has numerous advantages at multiple stages of the process, one of which is reduced equipment size, which in turn reduces capital costs. Other benefits of low water content include reduced energy consumption including reduced costs for pumping, heating, cooling and evaporation. Furthermore, the use of water adds significantly to the cost of the process, especially in dry environments.

Process stages that especially benefit from low levels of water content are pretreatment or other stages that require heat to process the feedstock. During these processes, the amount of energy required to heat the feedstock slurry, upstream of the reactor or in the reactor itself, is a direct function of the total mass of the feedstock slurry including the water added to transport the feedstock . Operating pretreatment or hydrolysis processes at low levels of water content reduces the energy required for heating. A variety of methods are known for heating the feed, including indirect heating methods (e.g. heating mantles), adding heated water to the chamber as disclosed in Canadian Patent Application No. 2638152, or adding steam to the reactor itself ( U.S. Patent No. 5,338,366).

One way to reduce the water content and consequent energy requirements for heating is to dehydrate the incoming feedstock and form a compaction plug of the feedstock before performing pretreatment or hydrolysis in a downstream reactor (see owned pending application WO2010022511, which is incorporated herein by reference). Feedstock plugs can be produced by various means such as plug screw feeders and subjected to screw pressure. Typically, the water content of the feedstock is reduced such that the solids content is high enough for plug formation to occur. Dewatering can take place in the plug forming device, or dewatering and plug forming can be performed in separate parts of the apparatus. Alternatively, dewatering upstream of plug formation may be omitted if the feedstock solids content is already at the desired high consistency.

The plug formed proved to be difficult to heat before it entered the downstream reactor. Typically, plugs are divided into larger segments, which may be 3-5 inches in diameter or even larger. This larger segment prevents steam from rapidly entering the fiber material and causing an uneven temperature distribution. The inventors have realized that non-uniform temperature distribution in the plug or sections thereof can lead to overcooking or undercooking of the feedstock in downstream reactors. Overcooking in the reactor can lead to degradation of the feedstock, while undercooking can lead to low xylose yield and difficulty hydrolyzing cellulose.

Accordingly, there is a need in the art for an improved apparatus for heating feedstock.

Utility model content

The purpose of this utility model is to provide an improved equipment for heating feed materials.

The utility model provides a device for heating and feeding materials, which comprises a long and long chamber, at least a part of which is cylindrical. The chamber comprises: (a) an inlet for receiving feedstock and an outlet for discharging heated feedstock; (b) a rotatable shaft coaxially mounted in the chamber, the shaft comprising: (i) an inlet section comprising an auger for conveying and breaking up the feed material in the inlet area of the chamber, wherein the auger comprises dimples or grooves formed therearound for breaking up the feed material , and (ii) a plurality of comminution elements mounted on at least an intermediate portion of said shaft for comminution of said feed material, said comminution elements protruding outwardly from said shaft and inclined relative to lines drawn transversely are offset by an angle; and (c) means for heating the comminuted feedstock particles as they are transported through the chamber.

According to one embodiment of the present invention, the dimples or grooves are v-shaped or substantially v-shaped.

According to another embodiment, the comminuting elements are inclined at an angle offset from about 5° to about 30° with respect to a line drawn transversely to said axis.

In yet another embodiment, the means for heating comminuted feedstock particles comprises one or more inlets for introducing steam.

According to another embodiment of the invention, comminuting elements are arranged on the shaft to sweep the inner surface of at least one region of the chamber.

According to another embodiment of the invention, the comminuting element is configured such that its outer edge exhibits one or more circles which are concentric or substantially concentric with respect to the inner surface of the chamber.

In another embodiment of the present invention, the crushing element is a blade, a bar, a paddle, a pin or an arm.

Description of drawings

In the attached picture:

Fig. 1 is the flowchart of the method according to the embodiment of the present utility model; And

Figure 2 is a cross-section of a sawtooth auger used in a heating chamber according to an embodiment of the invention.

Detailed ways

The following description is only an example of a preferred embodiment and does not limit the combination of features necessary to implement the utility model. The headings provided below are not intended to limit the different embodiments of the present invention. Terms such as "comprises" and variations thereof, "includes" and variations thereof are not limiting. In addition, the use of the singular includes the plural and "or" means "and/or" unless stated otherwise. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

Feed and Feed Size Reduction

The feedstock for this process is lignocellulosic material. The term "lignocellulosic feedstock" refers to any type of plant biomass such as but not limited to non-woody plant biomass; cultivated crops such as but not limited to grasses such as but not limited to C4 grasses such as switchgrass, Spartina , ryegrass, miscanthus, grass reed or combinations thereof; sugar processing residues such as but not limited to bagasse such as bagasse, beet pulp or combinations thereof; agricultural residues such as but not limited to soybean straw, corn stover, rice straw, Sugar cane straw, rice hulls, barley straw, corn cobs, wheat straw, canola straw, oat straw, oat hulls, corn fiber or combinations thereof; forestry biomass such as but not limited to recycled wood pulp fiber, sawdust, hardwood (such as aspen), cork, or combinations thereof. Additionally, the lignocellulosic feedstock may comprise lignocellulosic waste or forestry waste such as, but not limited to, newsprint, cardboard, and the like. A lignocellulosic feedstock may comprise one type of fiber, or a lignocellulosic feedstock may comprise a mixture of fibers derived from different lignocellulosic feedstocks. Additionally, the lignocellulosic feedstock may comprise fresh lignocellulosic feedstock, partially dried lignocellulosic feedstock, fully dried lignocellulosic feedstock, or combinations thereof. Furthermore, new species of lignocellulosic feedstocks may be produced from those listed above by crop breeding or by genetic engineering.

The lignocellulosic feedstock comprises a total of greater than about 20%, more preferably greater than about 30%, more preferably greater than 40% (w/w) cellulose. For example, the lignocellulosic material may comprise cellulose in an amount from about 20% to about 50% (w/w), or any amount therebetween. This feedstock comprises hemicellulose, which includes xylan, arabic acid, mannan and galactan. In addition, the lignocellulosic feedstock comprises lignin in a total amount greater than about 10%, usually greater than about 15% (w/w). The lignocellulosic feedstock also contained small amounts of sucrose, fructose and starch.

Lignocellulosic feedstocks are typically reduced in size by methods including, but not limited to, grinding, milling, stirring, chopping, compression/expansion, or other types of mechanical action. Size reduction by mechanical action may be effected by any type of equipment suitable for the purpose, such as, but not limited to, from the group consisting of hammer mills, drum mills, roller presses, refiners and hydropulpers. The size reduction device selected in . Feedstock can be reduced to particles having a length of about 1/16 to about 8 inches, or any amount in between. The length of the reduced particles can also be: at least about 90% of the particles by weight have a length less than about 5 inches or even shorter; for example, at least about 90% of the particles by weight have a length of less than about 4, about 3, about 2 , about 1 or about 1/2 inch in length. Washing may be performed to remove sand, grit, and other foreign particles that can cause damage to downstream equipment. It will be appreciated that there is no need to reduce the size of the lignocellulosic feedstock, for example, if the particle size of the feedstock is already between 1/2 to 8 inches.

For the purposes of this specification, the size of the feedstock particles is determined by image analysis using techniques known to those of ordinary skill in the art. Examples of suitable image analysis techniques are disclosed in Igathinathane (Sieveless particle size distribution analysis of particulate materials through computer vision, Computers and Electronics in Agriculture, 2009, 66:147-158, the subject matter of which is incorporated herein by reference), which describes Particle size analysis of several different beating milled feed materials was carried out. Measurements can be volume or weight average length.

Feed concentration

The amount of undissolved solids in the lignocellulosic feedstock may be adjusted to a desired concentration before feeding the lignocellulosic feedstock to the plug forming device. The lignocellulosic feedstock may have a solids concentration (undissolved dry solids) between about 1 wt% and about 40 wt% or between 4 wt% and about 20 wt% as it enters the plug forming device, and all ratios therebetween. The percentage of undissolved dry lignocellulosic feedstock solids can be determined at the inlet of the plug forming device. The desired concentration is determined by factors such as pumping capacity, piping requirements, and other practical issues.

The concentration of lignocellulosic feedstock (also referred to herein as undissolved solids or "UDS") can be determined by methods known to those skilled in the art. One known method is to filter the sample to remove undissolved solids, then dry the sample at a temperature for a period of time sufficient to remove water from the sample of slurry or wet material, but without causing thermal degradation of the feedstock solids. After removal of water or drying, the dry solids are weighed and the weight of water in a sample of slurry or wet material is the difference between the weight of the sample of slurry or wet solids and the weight of dry solids. The amount of undissolved dry solids in an aqueous slurry may be referred to as the consistency of the slurry. Concentration can be expressed as the weight of dry solids in a weight of slurry (eg, grams per kilogram), or as a percentage on a weight basis, such as % (w/w).

Prior to feeding the lignocellulosic feedstock to the plug forming device, the feedstock may be soaked in an aqueous solution comprising water or a solution comprising chemicals.

dehydration

The feedstock can be dewatered to increase the undissolved solids concentration within a desired range prior to plug formation. However, it should be understood that dewatering may not be required if the concentration of the feedstock is already at the desired level when the feedstock is supplied to the plug forming device. Dehydration may involve removing water from the feedstock under pressure (or at atmospheric pressure), as described below.

The plug forming device may be configured to dewater the feedstock, although separate corresponding devices for dewatering and plug formation may be employed. Without limitation, the plug forming device in combination with the dewatering section suitable for the present invention may be a pressurized screw press or a plug screw feeder, as in the pending application WO2010022511 owned by the inventor , which is incorporated herein by reference. The water squeezed from the lignocellulosic feedstock by the dewatering step can be reused in the process, for example for pulping and/or to saturate the incoming feedstock.

There are various known devices that can be used to dewater the feedstock prior to plug formation. Examples include grouting tanks, filtration devices, screens, screw presses, extruders, or combinations thereof.

If the feedstock is dehydrated under pressure, the pressure can be increased by one or more high pressure pumps. A pump or other feeding device increases the pressure of the feed to about 45 psia to about 900 psia, or about 70 psia to about 800 psia, or about 140 psia to about 800 psia, prior to dewatering. The pressure can be measured by a pressure sensor located at the feedstock inlet of the dewatering device or plug forming device which also dewaters the feedstock. Alternatively, the feedstock can be dewatered at atmospheric pressure or at pressures below 45 psia.

There may be an optional step of pre-draining the feedstock to drain the aqueous solution from the feedstock at atmospheric pressure or higher. The pre-discharged feedstock slurry can then be subjected to further dewatering.

plug forming device

Plug formation can be considered the incorporation of lignocellulosic particles into a compacted mass referred to herein as a plug. The plug forming device forms a plug that acts as a seal between areas of different pressure. In an embodiment of the invention, the plug acts as a seal against the higher pressure in the device downstream of the plug. However, it should be understood that the pressure may be higher at the inlet of the plug forming device.

As previously mentioned, the plug forming device may dewater the feedstock, or this function may be performed by an upstream dewatering device. A plug forming device that performs dewatering may comprise a housing or housing having openings for the passage of water. The plug forming device can operate at atmospheric pressure or under pressure.

Without limitation, the plug forming device may be a plug screw feeder, a pressurized screw press, a coaxial piston screw feeder, or a combined screw device.

The plug of lignocellulosic feedstock has a weight ratio of water to undissolved dry lignocellulosic feedstock solids of about 0.5:1 to 5:1, or about 1:1 to about 4:1, or about 1.5:1 to about 4:1, or about 1.5:1 to about 3.5:1, and all ratios in between. The weight ratio of water to dry undissolved lignocellulosic feedstock solids in the plug of lignocellulosic feedstock can be determined by the method described previously. Alternatively, the weight ratio of water to dry undissolved lignocellulosic feedstock solids can be determined by mass balance calculations.

crushing and steam exposure

The lignocellulosic feedstock is supplied to a downstream elongated chamber (also referred to herein as a "high shear heating chamber" or "heating chamber") where, as the feedstock is transported through the chamber, the The element breaks the feed material into granules. Typically, the heating chamber is oriented horizontally or substantially horizontally. The pulverized particles are heated by direct steam contact which allows efficient heat transfer.

At least a portion of the heating chamber is cylindrical. For example, while chambers that are cylindrical along their entire axial length are preferred, at least the middle region of the chamber may be cylindrical, and the inlet and outlet regions of the chamber may have different shapes. It should be understood that the term "cylindrical" includes frusto-conical or other substantially cylindrical shapes.

The plug or segments thereof need not be fed directly into the heating chamber. Various known devices can be positioned between the plug forming device and the heating chamber. Without limitation, examples of such devices include mechanical restraints, restraints, pin scrapers, and conveyors. It will be appreciated that the plug may be divided into segments as the plug is ejected from the plug forming device or into other devices positioned downstream of the plug forming device, or as the plug is fed to the heating chamber.

The chamber contains steam addition means for direct steam addition and a rotatable shaft mounted substantially coaxially in the chamber, the rotatable shaft containing one or more comminuting elements projecting outwardly from the shaft. Advantageously, it has been found that comminution of the plug or plug segment can be achieved using a comminution element which applies energy to the plug or plug segment in a shearing action. As discussed below, operating parameters can be selected for optimal feedstock comminution requirements.

As used herein, the term "shredding element" refers to one or more members arranged on a shaft that transport a feed plug or segments thereof through the chamber and apply sufficient shear to the feed , thereby producing pulverized feedstock particles when the shaft is selected at an appropriate speed. The comminuting elements may comprise blades, bars, paddles, pins or arms or combinations thereof. It should be understood that the length of the comminution elements may vary.

Comminution involves converting the plug or segments thereof into comminuted particles. Pulverized particles means that the fiber masses originating from the plug break down into their constituent particles in the heating chamber, or that the masses are significantly reduced in size in the high shear heating chamber. Without limitation, if wheat straw is used, the smallest dimension of the pieces may be less than about 10mm, or preferably less than about 5mm.

The tip speed of the comminution elements is selected to result in comminution of the feedstock and is generally higher than that used in mixing conveyors known in other industries. The tip speed of the comminuting elements may be between about 200 m/min and about 1000 m/min, or between about 450 and about 800 m/min, or any range therebetween. Shearing action is generally a function of the shape of the comminuting elements, the number of comminuting elements (if more than one is used), and tip speed. These parameters can be adjusted as necessary to achieve the desired shear rate.

In some embodiments of the invention, the comminuting element is located on the shaft, on at least the middle region of the shaft. The inlet region of the shaft may contain means for feeding and conveying the plug or segments thereof to the middle region of the shaft where more rapid comminution of the feedstock can occur. The outlet area of the shaft may contain means for delivering the plug to the outlet of the chamber.

In other embodiments of the invention, comminuting elements are located in the inlet and/or outlet region of the shaft. According to these embodiments, the elements of the inlet and/or outlet area of the shaft not only convey the feed material, but also comminute it. In some embodiments of the invention, the inlet region of the shaft comprises a belt feeder, a cutting chain auger or a sawtooth auger. This configuration improves throughput and minimizes blockage upstream of the heating chamber.

Some or all of the comminution elements may be inclined in the direction of feed material movement through the heating chamber to facilitate conveyance of the feed material through the heating chamber. That is, the comminuting elements are mounted on rotatable shafts, offset by an angle relative to a line drawn transversely to the heating chamber. This configuration reduces the residence time distribution of the feedstock, which in turn minimizes overheating or underheating of the feedstock. For example, the comminuting elements can be mounted on the shaft at an angle offset from 0° to about 45° relative to a line drawn transversely to the shaft. For example, the crushing element can be mounted on the shaft at an angle of 1° to about 45° offset relative to a line drawn transversely to the shaft, or at an angle of 5° to about 30° offset relative to a line drawn transversely of the shaft. superior.

The steam addition means may contain one or more inlets for direct steam injection. Introducing steam at spaced apart injection points along the length of the chamber allows for more uniform heating of the feedstock particles. Steam may be introduced through feed inlets, inlets arranged along the length of the chamber, or a combination thereof. Additionally, chemicals for pretreatment or hydrolysis can be introduced into the heating chamber.

The operating pressure and temperature of the heating chamber generally correspond to the pressure and temperature of the downstream reactor. The operating pressure of the chamber may be at least about 90 psia. Examples of suitable working pressures are comprised between about 90 and about 680 psia.

The temperature of the heating chamber is greater than about 100°C. Examples of temperature ranges include between about 100°C and about 280°C, or between about 160°C and about 260°C.

In some examples of the invention, the comminuting elements projecting outwardly from the shaft are configured such that their outer edges exhibit one or more circles that are concentric or substantially concentric with respect to the inner surface of the chamber. The term "substantially concentric" means that the one or more circles exhibited by the outer edge have an eccentricity of less than about 10% of the diameter of the heating chamber.

According to an embodiment of the invention, the distance between the inner surface of the chamber and the outer edge of the comminuting element closest to the inner surface (also referred to herein as "gap") is less than about 10% of the diameter of the chamber. As previously mentioned, the length of the comminuting elements can vary. Accordingly, the gap is measured at the outer edge of the comminuting element closest to the interior surface. In some embodiments of the invention, the gap is between about 2% and about 8%, or between about 2.5% and about 6%, of the inner diameter.

A comminution element is arranged on the shaft to sweep the interior surface of at least a region of the chamber. By sweeping the interior surfaces of at least one region of the chamber, the comminuting elements can reduce or remove scale build-up comprising lignin deposits that would reduce the transfer and mixing capabilities of the heating chamber.

The term "swept" means that the distance between the inner surface of the chamber and the outer edge of the comminuting element closest to the inner surface is less than 5% of the diameter of the chamber. By utilizing such gaps, fouling can be removed from the interior surfaces, or fouling can be reduced. Examples of suitable gap ranges for sweeping include about 1.0% to about 5.0%, about 1.5% to about 4.5%, or about 2.0% to about 4.0%.

Furthermore, if discrete comminuting elements are mounted on the shaft, such as blades, bars, paddles, pins or arms, the spacing between adjacent A stagnant area on the interior surfaces between comminuting elements where organic deposits build up on the interior surfaces of the chamber. For example, comminuting elements may overlap to provide a continuous axial sweep along at least one region of the chamber, thereby reducing or eliminating stagnant areas.

The utility model also relates to a lignocellulosic feedstock composition comprising: (i) pulverized lignocellulosic feedstock particles; (ii) about 15 to about 30 wt% undissolved solids, wherein the undissolved solids are contained in about Between 20 to about 60 wt% cellulose and between about 10 to about 30 wt% xylan; and (iii) a mineral acid, wherein the feedstock does not primarily comprise wood chips or pulp, the pH of the feedstock composition is between about Between 0.5 and about 3.5.

According to some embodiments of the present invention, the undissolved solids content is 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt% or 30wt%. The range of undissolved solids in the feed composition may be inclusive of the numerical limits of any of these values. According to other embodiments of the invention, the undissolved solids content is between about 18 wt% and about 28 wt%.

According to other embodiments of the invention, the pH of the feed composition is 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 or 3.5. The pH range of the feed composition may include the numerical limits of any of these values. According to other embodiments of the invention, the pH is between about 0.5 and about 3.0. The mineral acid can be sulfuric acid, sulfurous acid, hydrochloric acid, phosphoric acid or any combination thereof. Without limitation, the acid may be sulfuric acid.

The undissolved solids may comprise 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 60% by weight cellulose. Ranges for cellulose content in undissolved solids may include the numerical limits of any of these values. According to other embodiments of the present invention, the cellulose content in the undissolved solids may be between about 30 wt% and about 60 wt%.

The undissolved solids may comprise 10%, 15%, 20%, 25% or 30% by weight xylan. Ranges for xylan content in undissolved solids may include the numerical limits of any of these values. According to other embodiments of the invention, the xylan content in the undissolved solids may be between about 15 wt% and about 30 wt%.

The temperature of the composition may be at about 100°C, 120°C, 140°C, 160°C, 180°C, 190°C, 200°C, 220°C, 240°C, 260°C, or 280°C. Temperature ranges may include the numerical limits of any of these values. According to other embodiments of the invention, the temperature range may be between 160°C and 280°C.

The phrase "substantially free" means that the feedstock composition does not contain more than about 50% by weight wood chips or pulp. In some embodiments of the invention, the feedstock composition is substantially free of forestry biomass.

Pretreatment and Hydrolysis

After raising the temperature of the comminuted feedstock particles in the heating chamber, the comminuted feedstock particles may be pretreated or hydrolyzed.

The term "pretreatment" and variants thereof denote a process in which lignocellulosic feedstock is destroyed in the fiber structure and increases the susceptibility or accessibility of cellulose within the cellulosic fibers for subsequent enzymatic or The reaction is carried out under the conditions of the chemical transformation step. While the present invention also encompasses pretreatment processes that do not hydrolyze xylan, a portion of the xylan in the lignocellulosic feedstock may be hydrolyzed to xylose and other hydrolysis products in the pretreatment process. In an embodiment of the invention, the amount of xylan hydrolyzed to xylose is greater than about 50 wt%, about 60 wt%, about 70 wt%, about 80 wt%, or about 90 wt%.

The term "pretreated feedstock" means a feedstock that has been pretreated such that the cellulose contained in the cellulose fibers has increased susceptibility or accessibility to subsequent enzymatic or chemical conversion steps. The pretreated feedstock contains cellulose that was present in the feedstock prior to pretreatment. In some embodiments, at least a portion of the xylan contained in the lignocellulosic feedstock is hydrolyzed to produce at least xylose in the pretreatment.

According to embodiments of the invention, pretreatment or hydrolysis may or may not include the use of chemicals (e.g., hydrothermal pretreatment), and pretreatment or hydrolysis may be a feedstock that produces fermentable sugars or prepares them for subsequent conversion to fermentable sugars. Multi-stage or single-stage process of materials. All or a portion of the polysaccharides contained in the feedstock may be converted to oligosaccharides or monosaccharides, or a combination thereof, during pretreatment or hydrolysis. In other embodiments of the invention, pretreatment or hydrolysis includes the use of organic solvents, oxidizing agents, or inorganic acids or bases. Lignin may or may not be removed during pretreatment or hydrolysis.

According to one embodiment of the invention, at least a portion of the polysaccharides contained in the lignocellulosic feedstock is hydrolyzed to produce one or more monosaccharides.

Various types of reactors can be used to pretreat or hydrolyze feedstock, including two or more reactors arranged in series or in parallel.

According to one embodiment of the present invention, the reactor is a vertical reactor, which may be an upflow or downflow vertical reactor. In another embodiment of the present utility model, the reactor is a horizontal or inclined reactor. The reactor may be equipped with internal mechanical means, such as screws, conveyors, scrapers or similar mechanical means, for transporting lignocellulosic feedstock and/or to facilitate discharge from the reactor.

Chemicals for pretreatment or hydrolysis of the feedstock may be added to the feedstock during the soaking process prior to dewatering, prior to plug formation, to a heating chamber, to a plug forming device, to a reactor, or other in combination.

According to an embodiment of the invention, the pressure in the reactor is between about 90 psia and about 680 psia and any pressure therebetween. The pressure in the reactor can be measured by one or more pressure sensors. If one or more reactors are configured so that different pressure levels exist within each reactor, the pressure at the point where the feed enters the first reactor is considered herein to be the pressure of the reactor.

In some embodiments of the invention, the lignocellulosic feedstock is processed under acidic conditions in a reactor. For acidic conditions, suitable pHs are from about 0 to about 3.5, or from about 0.2 to about 3, or from about 0.5 to about 3, and all pH values therebetween.

According to other embodiments of the present invention, the acid added to set acidic conditions in the reactor is sulfuric acid, sulfurous acid, hydrochloric acid, phosphoric acid or any combination thereof. Adding sulfurous acid includes adding sulfur dioxide, sulfur dioxide plus water, or sulfurous acid. Organic acids may also be used alone or in combination with mineral acids.

According to another embodiment of the present invention, the base added to set alkaline conditions in the reaction zone is ammonia, ammonium hydroxide, potassium hydroxide, sodium hydroxide or any combination thereof.

The appropriate temperature and time for the reaction in the reactor depends on a number of variables including the pH in the reactor and the desired degree of hydrolysis of the polymer, if any.

Without limitation, the lignocellulosic feedstock can be pretreated under acidic or alkaline conditions. In the acidic pretreatment process, according to an exemplary embodiment of the present invention, the time in the pretreatment reactor may be from about 10 seconds to about 20 minutes, or from about 10 seconds to about 600 seconds, or from about 10 seconds to about 180 seconds. seconds, and any time in between. The temperature may be from about 150°C to about 280°C and any temperature therebetween. The pH of the pretreatment may be between about 0.5 and about 3, or between about 1.0 and about 2.0.

In the alkaline pretreatment process, the time in the reactor is from about 1 minute to about 120 minutes, or from about 2 minutes to about 60 minutes, and any time therebetween, and the suitable temperature is from about 20°C to about 220°C, or about 120°C to about 220°C, and any temperature therebetween.

Ammonia fiber expansion (AFEX), which is an alkaline pretreatment process, produces little or no monosaccharides. Therefore, if the AFEX treatment is used in the reaction zone, the hydrolyzate generated from the reaction zone may not produce any monosaccharides.

According to the AFEX process, cellulosic biomass is contacted with usually concentrated ammonia or ammonium hydroxide in a pressure vessel. This contact is maintained for a sufficient time for the ammonia or ammonium hydroxide to swell (ie, decrystallize) the cellulose fibers. The pressure is then rapidly reduced, allowing the ammonia to flash off or boil off and implode the cellulose fibrous structure. The flashed ammonia can then be recovered according to known processes. The AFEX process can be performed at about 20°C to about 150°C, or about 20°C to about 100°C, and any temperature therebetween. The duration of this pretreatment can be from about 1 minute to about 200 minutes, or any time therebetween.

Dilute ammonia pretreatment utilizes a more dilute solution of ammonia or ammonium hydroxide compared to AFEX. This pretreatment process may or may not produce any monosaccharides. Dilute ammonia pretreatment may be performed at about 100°C to about 150°C, or any temperature therebetween. The duration of this pretreatment can be from about 1 minute to about 20 minutes, or any time therebetween.

When ammonium hydroxide or potassium hydroxide is used for pretreatment, the temperature may be from about 100°C to about 140°C, or any temperature therebetween, and the duration of pretreatment may be from about 15 minutes to about 120 minutes, or any time therebetween, The pH may be from about pH 11 to about pH 13, or any pH value therebetween.

Alternatively, an acidic or alkaline hydrolysis process can be performed under conditions severe enough to hydrolyze cellulose to glucose and other products.

Sufficiently severe acidic hydrolysis of the hydrolyzed xylan and cellulose can be performed for about 10 minutes to about 20 minutes, or any time therebetween. The temperature may be between about 180°C and about 260°C, or any temperature therebetween. The pH can be between 0 and 1, or any pH in between.

Sufficiently severe alkaline hydrolysis of hydrolyzed xylan and cellulose can be carried out at about 125°C to about 260°C, or about 135°C to about 260°C, or about 125°C to about 180°C, or any temperature therebetween for about 30 minutes to about 120 minutes, or any time therebetween, and the pH is about 13 to 14, or any pH therebetween.

The pretreated or hydrolyzed feedstock can be discharged into a discharge device such as screw discharger, swept orifice discharger, rotary discharger, piston type discharger, etc. Two or more reactors arranged in series or in parallel may be used.

The hydrolyzed or pretreated feedstock exiting the reaction zone may be depressurized and rapidly cooled to, for example, between about 30°C and about 100°C. In one embodiment of the invention, the pressure is reduced to atmospheric pressure. Cooling and depressurization can be performed by one or more flash evaporators.

Enzymatic Hydrolysis and Fermentation

If the hydrolyzed and pretreated feedstock leaving the reactor contains cellulose, the feedstock can be hydrolyzed with cellulase enzymes. The term "cellulase", "cellulase" or "enzyme" means an enzyme that catalyzes the hydrolysis of cellulose to produce eg glucose, cellobiose and other cellooligosaccharides. Cellulase means the general term for a multi-enzyme mixture comprising exo-cellobiohydrolase (CBH), endoglucanase (EG) and β-glucosidase (βG) that can be produced by many plants and microorganisms . The process of the present invention can be carried out using any type of cellulase, regardless of its source.

Optionally, sugars resulting from pretreatment are separated from unhydrolyzed feedstock components in the pretreated feedstock slurry prior to enzymatic hydrolysis. Means to achieve separation include, but are not limited to, filtration, centrifugation, washing, or other known processes for removing fibrous or suspended solids. The sugar-containing vapor may then be concentrated, eg, by evaporation, using a membrane, or the like. Any traces of solids are typically removed by microfiltration.

In one embodiment, the sugar-containing vapor separated from the fiber solids is fermented to produce chemicals of interest, including but not limited to sugar alcohols. The sugar alcohol may be selected from xylitol, arbitol, erythritol, mannitol and galactitol. Preferably, the sugar alcohol is xylitol. Alternatively, the sugars are converted to alcohols, such as ethanol or butanol, by natural or recombinant bacterial or fungal fermentation.

In general, temperatures in the range of about 45°C to about 55°C, or any temperature in between, are suitable for most cellulases, even if the temperatures are higher for thermophilic cellulases. Cellulases are chosen to achieve a sufficiently high level of cellulose conversion. For example, a suitable dosage of cellulase may be from about 5.0 to about 100.0 filter paper units (FPU or IU) per gram of cellulose, or any amount therebetween. FPU is a standard metric familiar to those skilled in the art and is defined and measured according to Ghose (Pure and Appl. Chem. 1987, 59:257-268). The dosage level of beta glucosidase may be from about 5 to about 400-beta glucosidase units per gram of cellulose, or any amount therebetween, or from about 35 to about 100-beta glucosidase units per gram of cellulose, or any amount therebetween. [beta]-glucosidase units were also measured according to the Ghose method (see above).

The enzymatic hydrolysis of cellulose is continued for about 24 hours to about 250 hours, or any amount of time therebetween, depending on the degree of conversion desired. The resulting slurry is an aqueous solution containing glucose, xylose, other sugars, lignin and other unconverted suspended solids. Other sugars that may be generated in the reaction zone are also present in the aqueous solution. The sugars are readily separated from suspended solids and can be further processed as desired, such as, but not limited to, fermentation by yeast and fungi to produce fermentation products including, but not limited to, ethanol or butanol. If ethanol is produced, fermentation can be carried out with yeast, including but not limited to Saccharomyces cerevisiae.

Dissolved sugars undergoing fermentation may include not only glucose released during cellulose hydrolysis, but also sugars resulting from pretreatment, ie, xylose, glucose, arabinose, mannose, galactose, or combinations thereof. These sugars can be fermented together with the glucose produced by cellulose hydrolysis, or they can be fermented separately. In one embodiment of the invention, both glucose and xylose can be converted to ethanol by a Saccharomyces cerevisiae strain that has the ability to convert these sugars together with glucose from cellulose hydrolysis. Although some S. cerevisiae strains have been reported to be naturally capable of converting xylose to ethanol, a S. cerevisiae strain can be genetically engineered to produce this valuable by-product (see, e.g., U.S. Patent No. 5,789,210, incorporated by reference which is incorporated herein).

Detailed description of the drawings

As shown in FIG. 1 , a lignocellulosic feedstock slurry having a concentration of about 1% to about 10% (w/w), preferably about 3% to about 5% (w/w) on the pulp line 102 is passed through the feeder by means of a pump 104. Feed line 106 is pumped into a pressurized dewatering screw press (indicated by reference numeral 108). The pressurized dewatering screw press 108 comprises a solid housing 105 having a feed inlet 112 and an extrudate outlet 114 . Feed line 106 supplies lignocellulosic feedstock to dewatering screw press 108 via feed inlet 112 at a pressure of, for example, about 70 psia to about 900 psia. This pressure can be determined by measuring the pressure with a pressure sensor located at the feed inlet 112 .

The screen 116 is disposed within the housing 105 to provide an outer space 118 between the screen and the inner perimeter of the housing 105 . Screw 120 is concentrically and rotatably mounted within screen 116 . The flight 122 of the screw 120 has a generally constant outer diameter and is attached to a screw shaft having a core diameter that increases from an inlet end 124 to an outlet end 126 of the pressurized dewatering screw press 108 .

The water expressed from the lignocellulosic feed slurry, as well as any other liquids, including dissolved solids, is collected in space 118, which serves as a collection chamber for the recovered water. Space 118 is connected via extrudate port 114 to turbine 132 which draws reclaimed water via extrudate line 130 . The recycled water or extrudate may then be sent via line 134 to an extrudate return slurry makeup system (not shown).

Partially dewatered lignocellulosic feedstock exits the dewatering and plug forming zone of screw press 108 at outlet port 126 . The weight ratio of dry lignocellulosic feedstock solids to the partially dewatered lignocellulosic feedstock is preferably in the range of about 1.5:1 to about 4:1. The weight ratio of water to dry lignocellulosic feedstock solids in the dewatered lignocellulosic feedstock can be determined by collecting a sample of the feedstock from, for example, the screw press outlet port 126, and determining the weight ratio in the sample by the method described above. Sure. Alternatively, the weight ratio of water to dry lignocellulosic feedstock solids in the partially dewatered lignocellulosic feedstock can be determined by mass balance calculations.

The outlet end 126 of the pressurized screw press 108 is operatively connected to a plug region 136 . The plug of partially dewatered lignocellulosic feedstock is forced through plug region 136 and exits at plug outlet 137 . There is also a suppression device (not shown) at the plug outlet 137 .

The steam source configures steam inlet 138 and/or port 138A via steam inlet line 139 . A plug of partially dehydrated feedstock (containing water in the range of about 0.5 to about 5 times the dry feedstock solids weight) is fed to high shear heating chamber 140 via feed chamber 141 .

In the high shear heating chamber 140, the feed plug or segments thereof are broken down into particles which are heated by direct steam contact with steam introduced via line 139 and/or port 138A. Steam may also be introduced into the body of the heating chamber 140 . As previously described, the plug may be divided into segments as it exits the pressurized screw press 108 , or as it is fed to other devices located downstream of the screw press 108 .

The heating chamber 140 is a cylindrical horizontally oriented device having a concentric rotatable shaft 142 mounted coaxially within the chamber. The concentric shaft 142 contains a plurality of comminution elements 143 mounted in the middle region of the shaft and protruding radially from the shaft. Some comminution elements include a "T-shaped" distal end 144 for sweeping the interior surface of chamber 140, as described below. The inlet area of the shaft 142 contains an inlet auger 145 for feeding the plug or segments thereof into the middle area of the chamber. Furthermore, an outlet auger 146 with an opposite slope is provided in the outlet area of the shaft 142 for discharging the heated pulverized feedstock produced in the heating chamber 140 into the pretreatment reactor 152 .

Shear is applied to the feed plug or segments thereof in the heating chamber 140 by a plurality of comminuting elements 143 . The tip speed of the shaft is such that the feed section is comminuted and typically ranges from 450 m/min to about 800 m/min for optimal comminution. The extent of the shear action is primarily a function of the number and shape of the comminution elements multiplied by the tip speed. During comminution, the feed plug or segments thereof are broken into small particles.

Each comminution element is configured such that the gap between the inner surface of the chamber 140 and the “T-shaped” distal end 144 of each comminution element is less than 4% of the interior diameter of the chamber 140 . This clearance allows the comminution element 143 to sweep across the interior surfaces of the chamber 140 .

Furthermore, the comminuting element 143 is arranged on the shaft 142 so as to sweep the inner surface of the chamber 140 continuously axially. According to this embodiment of the invention, the end of each "T-shaped" comminuting element overlaps the corresponding end of an adjacent T-shaped element. This allows the area swept by each T-shaped element to overlap with the area swept by an adjacent T-shaped element, so that there are no stagnant areas for organic deposits to build up on the interior surfaces of the chamber.

According to another embodiment of the present invention, the crushing element is "Y-shaped". Furthermore, combinations of "Y-shaped" and "T-shaped" comminuting elements may be arranged on the shaft.

The auger 145 used to deliver the plug or segments thereof to the middle region of the chamber 140 may be a sawtooth auger. Cross-sections of various auger configurations suitable for use with the present invention are shown in FIG. 2 . Providing such an auger in the inlet region facilitates conveying the plug or segments thereof through the heating chamber 140 . In addition, a serrated auger is used to crush the feed plug or segments thereof before they enter the heating chamber.

The heated pulverized feedstock is discharged from the heating chamber 140 into a pretreatment reactor 152 comprising a cylindrical horizontally oriented vessel in which a screw conveyor 154 having a flight 156 is mounted. Pretreatment reactor 152 operates at a pressure of about 90 psia to about 680 psia, a pH of about 0.5 to about 3.0, and a temperature of about 160°C to about 260°C. The lignocellulosic feedstock is processed in the reactor for a period of about 10 to about 600 seconds. The desired pH in reactor 152 can be achieved by adding acid to the lignocellulosic feedstock prior to the inlet of the pressurized screw press.

A discharge device 158 discharges pretreated feedstock from the pretreatment reactor 152 . Subsequently, the pretreated feedstock is flashed in a flasher (not shown) to be cooled prior to enzymatic hydrolysis.

Claims (6)

1. heat an equipment for feed, it is characterized in that, comprise:

Lengthwise room, described room be cylindricality at least partially, described room comprises:

A () receives the entrance of described feed and discharges the outlet of the feed heated;

B () coaxially installs rotatable shaft in the chamber, described rotatable shaft comprises:

I () intake section, comprises for the entrance area transmission in described room and smashes the auger of described feed, described auger comprise be formed in around auger, for smashing pit or the groove of described feed; And

(ii) multiple crushing element, be arranged at least mid portion of described rotatable shaft, for pulverizing described feed, described crushing element from described rotatable shaft outwardly, and is inclined to the line drawn relative to the transverse direction along described rotatable shaft and offsets an angle; And

C () heats the device of the feed particles pulverized when the feed particles pulverized is conveyed through described room,

Wherein, described crushing element is arranged on the shaft, and with the inner surface at least one region of inswept described room, the region that described crushing element is configured to by each crushing element is inswept is overlapping with the region inswept by adjacent crushing element.

2. equipment as claimed in claim 1, it is characterized in that, described pit or groove are v shape or are roughly v shape.

3. equipment as claimed in claim 1, it is characterized in that, described crushing element is with such angular slope: the line skew about 5 ° to about 30 ° of drawing relative to the transverse direction along described rotatable shaft.

4. equipment as claimed in claim 1, it is characterized in that, the device of the feed particles that described heating has been pulverized comprises the one or more entrances for introducing steam.

5. the equipment according to any one of Claims 1-4, is characterized in that, the outward flange that described crushing element is configured to described crushing element demonstrate about described room inner surface with one heart or one or more circles of essentially concentric.

6. the equipment according to any one of Claims 1-4, is characterized in that, described crushing element is blade, bar, oar, pin, arm or their combination.