FIELD OF THE INVENTION

The present application relates generally to a conveyor . More specifically, the present application relates to the conveyor for pretreated biomass .

BACKGROUND OF THE INVENTION

Conveyors are used to transfer pretreated biomass from one process to another . A conveyor comprises a shafted conveyor screw to move the pretreated biomass from an inlet of the conveyor to an outlet . However, especially at high temperatures buildups may be formed on a surface of the shafted conveyor screw, which may require regular cleaning . It is important to find solutions wherein forming of the buildups could be avoided .

SUMMARY

This summary is provided to introduce a selection of concepts in a s implif ied form that are further described below in the detailed description . This summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter . The scope of protection sought for various embodiments of the present disclosure is set out by the independent claims .

The embodiments of the present disclosure provide a conveyor for pretreated biomass comprising at least one shaftless spiral , which may prevent forming of buildups . The shaftless spiral may stay cleaner and its cleaning may also be easier .

According to a first aspect a conveyor for pretreated biomass is disclosed . The conveyor may comprise : a cylindrical shel l that may comprise an inlet for receiving the pretreated biomass and an outlet whereat the pretreated biomass passes out of the cylindrical shell ; at least one shaftless spiral rotatably positioned in the cylindrical shell to move the pretreated biomass out of the cylindrical shell , wherein a temperature inside the cylindrical shell is from 120 °C to 250 °C .

For transferring hot , pretreated biomass , a shafted conveyor screw is usually used . At high temperatures , such as 120 °C to 250 °C, degradation products of carbohydrates and lignin release from the pretreated biomass may form sticky particles and deposits on the screw . Because of the hot surfaces of the screw and the hot environment in the conveyor the sticky biomass may form in the long run hard, condensated, and carboni zed material buildups onto the surface of the shaft and flights attached to the shaft or on the cylindrical shell surrounding the screw . This may hinder moving of the pretreated biomass and may even block the shafted conveyor screw totally . To prevent this , shafted conveyor screw may have to be stopped for cleaning regularly .

However, when using the shaftless spiral without a shaft , even in high temperatures , the buildups may not be formed on the saft , which may extend cleaning intervals and reduce production interruptions .

According to an embodiment of the first aspect , the conveyor may be a hemihydrolysis reactor or may be configured to be located at least partly inside the hemihydrolysis reactor . The hemihydrolysis reactor may be operated in high temperatures , for example between 120 °C to 250 °C, in which case it may be beneficial to use the shaftless spiral that may form none or less buildups at high temperatures .

According to an embodiment of the first aspect , the at least one shaftless spiral may be hollow . A hollow form may allow heat transfer medium to be placed inside the shaftless spiral . It may also lighten the structure . According to an embodiment of the first aspect , the shaftless spiral may comprise a channel configured to receive the heat trans fer medium within the channel to cool or warm an outer screw surface of the shaftless spiral . The channel may allow the heat transfer medium to be placed inside the shaftless spiral .

According to an embodiment of the first aspect , a temperature of the outer screw surface of the at least one shaftless spiral may be configured to be kept below a dew point of a surrounding atmosphere of the at least one shaftless spiral inside the cylindrical shell . When the temperature is configured to be kept below the dew point of the surrounding atmosphere , a condensate layer may be formed on the outer screw surface of the at least one shaftless spiral . The condensate layer may prevent sticky particles of the pretreated biomass to stick on the outer screw surface , therefor it may keep the surface clean and also make cleaning easier .

According to an embodiment of the first aspect , the heat transfer medium may be liquid or gas . This may allow use of different heat transfer mediums .

According to an embodiment of the first aspect , a spiral cross-section of the at least one shaftless spiral may be rectangular, triangle , half-circle , D- shaped, oval , or round . Different forms of the shaftless spiral may be used .

According to an embodiment of the first aspect , the cylindrical shel l may comprise at least one noz zle configured to spray liquid or gas to the at least one shaftless spiral . The noz zle may be used to clean the shaftless spiral and/or the cylindrical shell from the buildups ; and/or to prevent the buildups to stick on them .

According to an embodiment of the first aspect , the at least one shaftless spiral may be located inside the cylindrical shel l having about the same or smal ler approximate outer spring diameter as an inner shell diameter of the cylindrical shell . When the shaftless spiral has about the same or close the same approximate outer spring diameter as the inner shell diameter, there may be friction between the inner shell surface of the cylindrical shell and the shaftless spiral conveyor screw . The friction may keep the inner shell surface and also at least part of the outer screw surface clean so that no extra cleaning may be needed .

According to an embodiment of the first aspect , the outer spring diameter of the at least one shaftless spiral may be larger than a particle si ze of the pretreated biomass . This may allow the shaftless spiral to move the pretreated biomass effectively .

According to an embodiment of the first aspect , the at least one shaftless spiral may be conf igured to allow a nominal vibration . The vibration may help to clean the shaftless spiral and also help to keep it clean by preventing the buildups to stick on the outer screw surface .

According to an embodiment of the first aspect , the nominal vibration may be configured to be caused by a vibration means , pressure changes in the heat transfer medium, and/or a change in rotation direction and/or speed of the at least one shaftless spiral . Different means may be used to produce the vibration .

According to an embodiment of the first aspect , the at least one shaftless spiral and/or the inner shell surface may be configured to be at least partly coated with a coating material or at least partly polished . Coating or polishing may help to clean the shaftless spiral and/or the inner shell surface , and it may also help to keep them clean by preventing the buildups to stick on them .

According to an embodiment of the first aspect , the pretreated biomass may be pretreated wood biomass .

According to a second aspect , a system comprising a hemihydrolysis reactor comprising a hemihydrolysis reactor vessel and at least one conveyor according to the first aspect is disclosed . The at least one conveyor may be configured to be located at least partly inside the hemihydrolysis reactor vessel . The hemihydrolysis reactor may use high temperatures , in which case it may be beneficial to use the shaftless spiral to prevent build-up forming .

According to an embodiment of the second aspect , a residence time of the pretreated biomass in the hemihydrolysis reactor vessel and in the at least one conveyor may be from 1 second to 120 minutes .

According to an embodiment of the second aspect , composition of the pretreated biomass in the hemihydrolysis reactor vessel and in the at least one conveyor may comprise biomass particles and/or lignocellulose particles . Preferably the composition of the pretreated biomass is a mixture of wood particles , l ignocellulose , solid lignin, soluble lignin, carbohydrates , extractives , soluble sugar monomers , and sugar oligomers , for example . Degradation products of carbohy- drates /sugars , extractives and lignin may form sticky precipitates , and the at least one shaftless spiral may prevent the buildups to stick on the surface of the shaftless spiral . Due to higher friction between the surface of the cylindrical shell and the at least one shaftless spiral , constant removal of the sticky substances may not be needed .

According to a third aspect , use of the conveyor according to the first aspect for moving pretreated biomass is disclosed .

According to a fourth aspect , a method for moving pretreated biomass with a conveyor is disclosed . The conveyor may comprise : a cylindrical shell that may comprise an inlet and an outlet ; and at least one shaftless spiral rotatably positioned in the cylindrical shell ; wherein a temperature inside the cylindrical shell may be from 120 °C to 250 °C . The method may comprise receiving the pretreated biomass from the inlet ; moving, by the at least one shaftless spiral conveyor screw, the pretreated biomass from the inlet to the outlet ; and passing the pretreated biomass out of the cylindrical shell through the outlet . When using the shaftless spiral conveyor screw, even at high temperatures , the buildups may not be formed which may extend cleaning intervals and reduce production interruptions .

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

Figure 1 shows schematically an example of a system according to an embodiment ;

Figure 2 shows schematically an example of the conveyor comprising a shaftless spiral according to an embodiment ;

Figure 3 shows schematically an example of the conveyor comprising a shaftless spiral comprising a channel according to an embodiment ;

Figure 4 shows schematically an example of a conveyor cross-section according to an embodiment ;

Figure 5 shows schematically an example of a shaftless spiral cross-section according to an embodiment ; and

Figure 6 shows an example method according to an embodiment .

Like references are used to designate like parts in the accompanying drawings . DETAILED DESCRIPTION

Reference will now be made in detail to embodiments , examples of which are illustrated in the accompanying drawings . The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utili zed . The description sets forth the functions of the example and the sequence of steps or operations for constructing and operating the example . However, the same or equivalent functions and sequences may be accomplished by different examples .

One or more conveyors may be located inside a hydrolysis reactor . The conveyor may transfer pretreated biomass out of the hydrolysis reactor . The conveyor may comprise a shafted conveyor screw to move the pretreated biomass from a conveyor inlet to a conveyor outlet . However, especially in high temperature conditions buildups may be formed on a surface of the shafted conveyor screw which may require regular cleaning .

The shafted conveyor screw may be arranged at the bottom of a hydrolysis reactor to transfer the pretreated biomass . Since the temperature of the transferred pretreated biomass is high, buildups on the shafted conveyor screw may affect its efficient operation and may even block the shafted conveyor screw and an outlet of the conveyor . Clean keeping of the shafted conveyor screw at high temperatures may be very challenging . Typically buildups may be formed onto the surface of the hydrolysis reactor and the shafted conveyor screw at a temperature range from 120 °C to 250 °C . I f the pretreated biomass becomes sticky at a certain point of a process , and if a pretreated biomass stream is not moving forward, the pretreated biomass may stay on the hot surface for a long time and may form in a long run hard buildups , which is , for example , carboni zed material , onto the surface of the shafted conveyor screw . This may cause the shafted conveyor screw to be totally blocked, and the hydrolysis reactor may have to be stopped for cleaning regularly . The buildups may also be seen inside of the hydrolysis reactor both on certain locations of a hydrolysis reactor chamber wall , and on the shaft and flights of the shafted conveyor screw .

In this specification and claims a reactor may be a pretreatment reactor, a steam explosion reactor, hydrothermal treatment reactor, or a hemihydrolysis reactor .

In this specification and claims the term pretreated biomass refers to biomass particles and/or lignocellulose particles . Preferably the composition of the pretreated biomass is a mixture of of wood particles , lignocellulose , solid lignin, soluble lignin, carbohydrates , extractives , soluble sugar monomers , and sugar oligomers .

According to an embodiment , the pretreated biomass may be pretreated wood biomass . The pretreated wood biomass may be formed in a process where wood chips may be treated by impregnation followed by hemihydrolysis in the hemihydrolysis reactor with high temperature , steam, and pressure . The wood chips may be hardwood chips , such as beech, birch, ash, oak, maple , chestnut , willow, or poplar chips . The wood chips may also be any combination or mixture of these . The impregnation may be accompl ished by treating the wood chips with an impregnation liquid . The impregnation liquid may be water or acidic liquid . Preferably the impregnation liquid is sulfuric acid . The impregnated wood chips may be transferred to hemihydrolysis reactor where the wood chips may be subj ected to hemihydrolysis reaction . The hemihydrolysis reaction may be carried out by treating the impregnated wood chips with high temperature steam . The temperature in the hemihydrolysis reactor may be from 120 °C to 250 °C, and the pressure may be 1 - 20 bar or 2 - 16 bar, for example. Temperature of the pretreated biomass in the hemihydrolysis reactor is, for example, 120°C to 250°C. More preferably temperature of the pretreated biomass in the hemihydrolysis reactor is, for example, 150°C to 220°C or 185°C to 195°C. Finally the pretreated wood biomass may be transferred out of the hemihydrolysis reactor by the at least one conveyor to be treated further by steam explosion so that fibers may be separated.

An example of Figure 1 shows schematically a system comprising a hemihydrolysis reactor comprising a hemihydrolysis reactor vessel 9 and at least one conveyor 1. The at least one conveyor may be located at least partly inside the hemihydrolysis reactor vessel 9. Hemihydrolysis reaction started in the hemihydrolysis reactor vessel 9 may continue also in the at least one conveyor 1. The hemihydrolysis reactor is an area where conditions for hemihydrolysis reaction may be present. In the system the hemihydrolysis reaction may happen inside the hemihydrolysis reactor, which means inside the hemihydrolysis reactor vessel 9 and/or inside the at least one conveyor. In the other words, the hemihydrolysis reaction conditions of the hemihydrolysis vessel 9 may be prevailed in the conveyor 1. The hemihydrolysis reaction may require high temperatures, for example, 120°C - 250°C, preferably 150°C - 220 °C, more preferably 185°C - 195°C. In addition to the high temperature, the hemihydrolysis reaction may require steam, and pressure of 1 - 20 bar or 2 - 16 bar, for example. Saturated steam pressure may correspond a saturated steam temperature inside the reactor.

The term "hemihydrolysis" may refer to a treatment in which the impregnated and/or pretreated biomass is treated in a reactor, for example a hemihydrolysis reactor with steam having a temperature of or 120°C - 250°C, 150°C - 220°C, or 185°C - 195°C. The purpose of the treatment is to degrade and solubilize the hemicellulose contained in the biomass and to break down the biomass structure so that the cellulose may get accessible for enzymes ( cellulases ) and may be converted to glucose in high yields in the next t reatment step after the hemihydrolisis .

The conveyor 1 may comprise a cylindrical shell 2 and a shaftless spiral 3 , 3b according to examples of Figure 2 and Figure 3 . According to an embodiment the conveyor 1 is a hemihydrolysis reactor or is configured to be located inside the hemihydrolysis reactor . When the at least one conveyor 1 is located at least partly inside the hemihydrolysis reactor, conditions for hemihydrolysis may be present also in the at least one conveyor 1 . Thus the at least one conveyor 1 may operate in the hemihydrolysis reaction conditions , at a temperature from 120 °C to 250 °C .

According to an embodiment , the at least one conveyor 1 may be conf igured to be located at a bottom part of the hemihydrolysis reactor vessel 9 . The at least one conveyor 1 may be configured to be located at least partly inside the hemihydrolysis reactor vessel 9 . The system may comprise a plurality of conveyors 1 , which may or may not be the same type of conveyors . Pretreated biomass 4 may be fed into the hydrolysis reactor vessel 9 according to arrow 10 and treated with high temperature , added steam ( according to arrow 11 ) , and pressure . A temperature inside the cylindrical shell 2 and/or in the hydrolysis reactor vessel 9 is , for example , from 120 °C to 250 ° C . More preferably the temperature inside the cylindrical shell and/or the hydrolysis reactor vessel 9 is , for example , from 150 °C to 220 °C . After the hydrolysis , the hydrolyzed pretreated biomass 4 may be removed by the at least one conveyor 1 from the material outlet 6 according to arrow 0.

According to an embodiment , composition of the pretreated biomass 4 in the hemihydrolysis reactor vessel 9 and/or in the at least one conveyor 1 comprises biomass particles and/or lignocellulose particles . Preferably the composition of the pretreated biomass is a mixture of wood particles , lignocellulose , solid lignin, soluble lignin, carbohydrates , extractives , soluble lignin fragments , soluble sugar monomers , sugar oligomers , and degradation products thereof , for example . The pretreated biomass may comprise bigger particles , for example , cooked and crushed wood particles and soluble components .

According to an embodiment , a spiral crosssection B-B of the at least one shaftless spiral 3 , 3b is rectangular, triangle , half-circle , D-shaped, oval , or round .

According to an embodiment , the at least one shaftless spiral 3 , 3b located inside the cylindrical shell 2 has about the same or smaller approximate outer spring diameter d as an inner shell diameter D of the cylindrical shell 2 . A flight distance F between the outer screw surface 7 of the at least one shaftless spiral 3 , 3b and an inner shell surface 8 of the cylindrical shell 2 is from 0 , 1 mm to 5 mm, for example . The flight distance F = ( D - d) / 2 . The flight distance F may be the shortest distance between the outer screw surface 7 and the inner shell surface 8 . The outer screw surface 7 may comprises all the sides of the shaftless spiral 3 , 3b or is a j acket around the shaftless spiral 3 , 3b . When the shaftless spiral 3 , 3b has about the same or close the same approximate outer spring diameter d as the inner shell diameter D, there may be a friction between the inner shell surface 8 and the outer screw surface 7 , which friction may keep the inner shell surface 8 and/or the outer crew surface 7 at least partly clean so that no additional cleaning may be needed for the inner shell surface 8 and/or the outer screw surface 7 . According to an embodiment , the outer spring diameter d of the at least one shaftless spiral 3 , 3b is larger than a particle si ze of the pretreated biomass 4 . This may allow conveyor to move the biomass 4 effectively . A wood chip particle inside the hydrolysi s reactor may have particle si ze , wherein the length is from 10 mm to 40 mm, thickness is from 2 mm to 15 mm, and width from 10 mm to 30 mm, for example .

According to an embodiment , the at least one shaftless spiral 3 , 3b is configured to allow a nominal vibration . The vibration may squeeze and extend the shaftless spiral 3 , 3b . The shaftless spiral 3 , 3b may be configured to be designed to allow nominal vibration . The vibration may help to clean the shaftless spiral 3 , 3b . The vibration may also prevent the buildups to be stuck on the outer screw surface 7 of the shaftless spiral 3 , 3b .

According to an embodiment , the nominal vibration is configured to be caused by a vibration means , pressure changes in the heat transfer medium inside the shaftless spiral 3b, and/or a change in a rotation direction and/or speed of the at least one spiral conveyor screw 3 , 3b . The vibration means may comprise a mechanical hammer and/or a vibrator . The vibration means may be located inside or outside of the cylindrical shell 2 . The shaftless spiral 3 , 3b may shrink when moved to a certain direction, a first direction, and extend when moved to an opposite direction, a second direction . This way the change in the rotation direction R may be used to remove the buildups . When the shaftless spiral 3 , 3b extends or shrinks , the outer spring diameter d may change and cause the shaftless spiral 3 , 3b to vibrate and to remove buildups .

According to an embodiment , the cylindrical shell 2 compri ses at least one noz zle 20 conf igured to spray high pressure liquid or gas to the at least one shaftless spiral 3 , 3b . Spraying may be done with high pressure liquid or gas. The liquid may be water. Water may comprise chemicals, for example, sodium hydroxide. The gas may be steam, for example, water steam. The nozzles 20 may be located at various locations along the inner shell surface 8. The at least one nozzle 20 may be configured to inject gas or liquid inside the conveyor 1 towards the at least one shaftless spiral 3, 3b. The at least one nozzle 20 may be configured to clean the shaftless spiral 3, 3b and/or the inner shell surface 8 from the buildups, and/or to prevent the buildups to stick on the outer screw surface 7 and/or on the inner shell surface 8.

According to an embodiment, the at least one shaftless spiral 3, 3b and/or the inner shell surface 8 is configured to be at least partly coated with a coating material and/or at least partly polished. It may be possible to coat at least part of the shaftless spiral 3, 3b with the coating material and polish at least part of the inner shell surface 8 or vice versa. It may also be possible that at least part of the shaftless spiral 3, 3b may be coated with the coating material. For example, at least back side of shaftless spiral 3, 3b may be coated with the coating material, and rest of the shaftless spiral 3, 3b may be polished. The back side of the shaftless spiral 3, 3b is the side facing towards the inlet 5 of the shaftless spiral 3, 3b. According to an embodiment, the at least one shaftless spiral 3, 3b is configured to be coated with coating material and/or polished at least partly around the outer screw surface 7 of the at least one shaftless spiral 3, 3b.

According to an embodiment, at least part of an outer screw surface 7 of the at least one shaftless spiral 3, 3b and/or at least part of an inner shell surface 8 of the cylindrical shell 2 is configured to be coated with the coating material having electrical charge. The coating material having electrical charge may be a positively surface charged material or negatively surface charged material . According to an embodiment , the coating material having electrical charge is polymer .

According to an embodiment , at least part of the outer screw surface 7 of the at least one shaftless spiral 3 , 3b and/ or at least part of the inner shel l surface 8 of the cylindrical shell 2 is configured to be coated with the coating material having low adhesion tendency . With a term " low adhes ion tendency" is meant ability that prevents the buildups to stick on the surface of the shaftless spiral 3 , 3b and/or the cylindrical shell 2 . This kind of coating material may have low adsorption ability . The coating material having low adhesion tendency may be polymer, ceramic, enamel or glass . Polymer may be conf igured to be selected from a family of fluoropolymers or polyaryletherketones ( PAEK) . Fluoropolymer is , for example, polytetrafluoroethylene ( PTFE ) or perfluoroalkoxy alkane ( PFA) .

According to an embodiment , fluoropolymer comprises electrically conductive material . The electrically conductive material may be conductive filler, for example , conductive carbon material .

According to an embodiment , Plasma-technology or dip-coating is configured to be used for coating .

According to an embodiment , the at least one shaftless spiral 3 , 3b and/or the cylindrical shell 2 may be configured to be at least partly coated with the coating material and/or polished . Coating or polishing may be done all around or at least partly around the at least one shaftless spiral 3 , 3b and/or inside the conveyor shell 2 .

When at least part of the outer screw surface 7 and/or the inner shell surface 8 is polished a roughness value Ra of the outer screw surface 7 and/or the inner shell surface 8 may be extremely low, for example , like a surface of a mirror . The Ra value of the outer screw surface 7 and/or the inner shell surface 8 is , for example , less than 1 , 6 microns , preferably less than 0 , 1 microns , or more preferably less than 0 , 05 microns . The term "Ra value" should in this specification, unless otherwise stated, be understood as an average roughness of a surface . Ra is an arithmetic average value of a deviation of a trace above and below a center line . Standard SFS-EN 10049 : 2013 provides more details for measuring the Ra value .

According to an embodiment , a residence time of the pretreated biomass 4 in the hemihydrolysis reactor vessel 9 and the at least one conveyor 1 is from 1 second to 120 minutes . When the at least one conveyor 1 is the hemihydrolysis reactor the residence time of the pretreated biomass 4 in the at least one conveyor 1 is 1 second to 120 minutes . More preferably the residence time is from 1 second to 30 minutes . The term "residence time" should in this specification, unless otherwise stated, be understood as the time between the pretreated biomass being introduced into or entering the hydrolysis reactor vessel 9 or at least one conveyor 1 , and the pretreated biomass 4 exited or discharged from the at least one conveyor 1 . I f there are more than one conveyors 1 , the exiting or discharging is from the latest conveyor 1 .

According to an embodiment , the at least one conveyor 1 according to Figure 2 and/or Figure 3 may be used to remove the pretreated biomass 4 from the hydrolysis reactor vessel 9 of Figure 1 . The at least one conveyor 1 may also be used as an hemihydrolysis reactor alone without the hydrolysis reactor vessel 9 .

An example of Figure 2 shows schematically a conveyor 1 comprising a shaftless spiral 3 . The conveyor 1 may comprise a cylindrical shell 2 comprising an inlet 5 for receiving the pretreated biomass 4 . The conveyor 1 may receive the pretreated biomass 4 from the bottom of the hemihydrolysis reactor 9 , an outlet 6 of another conveyor 1 , or from another process . The conveyor 1 may also be hemihydrolysis reactor itself . In that situation, the hemihydrolysi s reaction may happen in the at least one conveyor 1 and no separate hydrolysis reactor vessel 9 may be needed . The cylindrical shell 2 may also comprise and an outlet 6 whereat pretreated biomass 4 may pass out of the cylindrical shell 2 . Entering and passing out of the pretreated biomas s 4 are shown with arrows I and 0. The conveyor 1 may further comprise at least one shaftless spiral 3 rotatably positioned in the cylindrical shell 2 to move the pretreated biomass 4 out of the cylindrical shell 2 . The shaftless spiral 3 does not have any shaft , wherein the pretreated biomass 4 could stick . The inlet support member 12 supports the shaftless spiral 3 from an inlet part and an outlet support member 13 supports the shaftless spiral 3 from an outlet part allowing it to rotate . The at least one shaftless spiral 3 may rotate within the the cylindrical shell 2 to move the pretreated biomass 4 within the cylindrical shell 2 from the inlet 5 to the outlet 6 . The shaftless spiral 3 may have the outer screw surface 7 and the outer spring diameter d . The cylindrical shell may have an inner shell surface 8 and the inner shell diameter D .

While the conveyor 1 in Figure 1 illustrates only one shaftless spiral 3 within the cylindrical shell 2 , the number of the shaftless spirals 3 , 3b in Figures 2 and 3 within the cylindrical shell 2 should not be considered limiting on the current disclosure . For example , in some examples , multiple shaftless spirals 3 , 3b may be provided within the cylindrical shell 2 . When the conveyor has more than one shaftless spiral , they may clean each other .

An example of Figure 3 shows schematically a conveyor 1 comprising a shaftless spiral 3b . The conveyor 1 of Figure 3 may be the same as in Figure 2 expect the shaftless spiral 3b may comprise a channel 21 . Also , an inlet support member 12 and an outlet support member 13 may be hollow to allow a heat transfer medium to enter through the inlet support member 12 to the channel 21 of the shaftless spiral 3b and leave the channel 21 through the outlet support member 13 .

According to an embodiment , the at least one shaftless spiral is hollow . The hollow shaftless spiral 3b may allow heat trans fer medium to be placed inside the hollow shaftless spiral 3b . It may also lighten the structure . The shaftless spiral 3b may be internally cooled with a coolant and/or warmed with heat agent . The conveyor 1 comprising the at least one shaftless spiral 3b may may be used in hemidydrolysis reactor of Figure 1 or alone as a hydrolysis reactor .

According to an embodiment, the shaftless spiral 3b comprises a channel 21 configured to receive the heat transfer medium within the channel 21 to cool or warm an outer screw surface 7 of the shaftless spiral 3b . A hollow part of the shaftless spiral 3b may be the channel 21 . The channel 21 may be formed inside the shaftless spiral 3b . The outer screw surface 7 of the shaftless spiral 3b may contact the pretreated biomass 4 . The shaftless spiral 3b may allow the heat transfer medium to be placed inside the channel 21 to cool or warm the outer screw surface 7 of the shaftless spiral 3b inside the cylindrical sell 2 . As the coolant flows through the shaftless spiral 3b, the temperature of the coolant may increase due to contact of the outer screw surface 7 of the shaftless spiral 3b . As the the heat agent flows through the shaftless spiral 3b, the temperature of the heat agent may decrease due to contact of the outer screw surface 7 of the shaftless spiral 3b . The coolant or the heat agent may be directed inside the shaftless spiral 3b as indicated by arrow S and out of the shaftless spiral 3b as indicated by arrow U . The coolant or the heat agent may be directed inside the channel 21 through the hollow inlet support member 12 from an inlet side of the conveyor 1 and out of the channel 21 from the hollow outlet support member 13 from an outlet side of the conveyor 1. The the heat transfer medium and the pretreated biomass 4 may move in the same direction inside the conveyor 1.

According to an embodiment, a temperature of the outer screw surface 7 of the at least one shaftless spiral 3b is configured to be kept below a dew point of a surrounding atmosphere of the shaftless spiral 3b located inside the cylindrical shell 2. The temperature of the outer screw surface 7 is, for example, from 0,1 to 20 °C below the dew point of the surrounding atmosphere. Preferably, the temperature is from 0,1 to 2 °C below the dew point. It may be beneficial to minimize temperature difference between the outer screw surface 7 and the atmosphere to save energy. Also, the pretreated biomass 4 may have to be kept hot in the reactor.

The atmosphere may be a space inside the inner shell surface 8. The atmosphere may comprise steam inside the conveyor shell 2. The steam may be saturated steam. The steam may be formed from water. The steam may have 100 % relative moisture content. The steam that exists at the same temperature as the liquid from which it is formed is known as the saturated steam. When the at least one shaftless spiral may be configured to be kept below the dew point of the surrounding atmosphere of the shaftless spiral, it may form a condensate layer on the outer screw surface 7 of the at least one shaftless spiral 3b. The condensate layer may prevent sticky particles of the pretreated biomass 4 to stick on the outer screw surface 7 and make cleaning easier or even needless .

According to an embodiment, the coolant and/or the heat agent is liquid or gas. The coolant or the heat agent may be at least one of the following: air, steam, water, oil glycol, and/or medium standing temperature range of from 0°C to 250°C. An example of Figure 4 shows schematically a conveyor cross-section A - A . The shaftless spiral 3 , 3b may be according to Figure 2 or Figure 3 . The location of the cross-section A - A is shown in Figures 2 and 3 with arrows A in the inlet side of the shaftless spiral 3 , 3b . As seen from the Figure 4 the shaftless spiral 3 , 3b may rotate counterclockwise as shown with the rotation direction arrow R . In the other words , the shaftless spiral 3 , 3b may move the pretreated biomas s 4 from the material inlet 5 to the material outlet 6 . When the shaftless spiral 3 , 3b is rotating counterclockwise it may shrink . This may push the pretreated biomass 4 from the inlet 5 to the outlet 6 .

When the shaftless spiral 3 , 3b is rotating clockwise it may extend, cause nominal vibration, and remove the buildups from the outer screw surface 7 and/or the inner shell surface 8 . According to an embodiment , when the shaftless spiral 3 , 3b is rotating clockwise , the outer spring diameter d may extend in some cases to reach the inner shell diameter D and may stop rotation of the shaftless spiral 3 , 3b, which may remove the buildups from the outer screw surface 7 and/or the inner shel l surface 8 . The friction between the outer screw surface 7 and the inner shell surface 8 may cause this . In a first direction the shaftless spiral 3 , 3b may move the pretreated biomass 4 from the material inlet 5 to the material outlet 6 and in the second direction, opposite to the first direction, the shaftless spiral 3 , 3b may cause the nominal vibration and remove the buildups .

According to an embodiment , the nominal vibration is configured to be caused by a change in a rotation direction R of the at least one spiral 3 , 3b . In the first direction the shaftless spiral 3 , 3b may move the pretreated biomass 4 from the material inlet 5 to the material outlet 6 . In the second direction, opposite to the first direction, the shaftless spiral 3 , 3b may cause the nominal vibration and remove the buildups . In the first direction the shaftless spiral 3 , 3b may push and in the second direction it may pull .

An example of Figure 5 shows schematically a spring cross-section B - B of the shaftless spiral 3b . The shaftless spiral 3b may be according to Figure 3 . The location of the cross-section B - B is shown in Figure 4 with arrows B . In the example of Figure 5 the spring cross-section B - B is rectangular .

According to an embodiment the spiral crosssection B - B of the at least one shaftless spiral 3 , 3b is rectangular, triangle , half-circle , D-shaped, oval , or round .

Figure 6 illustrates an example of a method for moving pretreated biomass 4 with a conveyor, wherein the conveyor 1 comprises a cylindrical shell 2 comprising an inlet 5 and an outlet 6 , and at least one shaftless spiral 3 , 3b rotatably positioned in the cylindrical shell 2 , wherein a temperature inside the cylindrical shell is from 120 °C to 250 °C .

At operation 600 , the method may comprise receiving the pretreated biomass 4 from the inlet 5 .

At operation 610 , the method may comprise moving, by the at least one shaftless spiral 3 , 3b, the pretreated biomass 4 from the inlet 5 to the outlet 6 .

At operation 620 , the method may comprise passing the pretreated biomass 4 out of the cylindrical shell 2 through the outlet 6 .

Further features of the method directly result from functionalities of , for example , the conveyor 1 . Different variations of the method may be also applied, as described in connection with the various embodiments .

The conveyor 1 may be configured to perform or cause performance of any aspect of the method described herein .

Any range or device value given herein may be extended or altered without losing the effect sought . Also , any embodiment may be combined with another embodiment unless explicitly disallowed .

Although the subj ect matter has been described in language specific to structural features and/or acts , it is to be understood that the subj ect matter defined in the appended claims is not necessarily limited to the specific features or acts described above . Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims .

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benef its and advantages . It wi ll further be understood that reference to ' an ' item may refer to one or more of those items .

The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate . Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subj ect matter described herein . Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought .

The term ' comprising ' is used herein to mean including the method, blocks , or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements .

Although subj ects may be referred to as ' first ' , ' second' , or ' third' subj ects , this does not necessarily indicate any order or importance of the subj ects . Instead, such attributes may be used solely for the purpose of making a difference between subj ects . It will be understood that the above description is given by way of example only and that various modifica- tions may be made by those skilled in the art . The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments . Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments , those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification .