The field of technology

The invention concerns the method of processing of 1ignocellulose materials by continuous pressure hydrolysis giving rise to lignin, furfural or furane , furfuralalcohol , acetic and formic acid, cellulose or glucose and 10 corresponding equipment for performance of this method.

Current state in the field of technology

Hydrolysis of lignocellulose materials was carried out 15 by sulphuric acid, later utilisation of sulphurous acid was tested. More modern percolation procedure of hydrolysis was elaborated by Scholler, who used equipment, where vapour, containing sulphuric acid, passed through raw material to be hydrolysed . Countercurrent hydrolysis 20 of moist raw material by 37 % hydrochloric acid or by gaseous hydrogen chloride is known .

Enzymatic method of hydrolysis was also tested. But on industrial scale only hydrolysis by diluted sulphuric acid in percolation reactor is utilised.

Continuous method of hydrolysis of lignocellulose materials has not been utilised on industrial scale. In operational conditions it is difficult to keep short reaction times, to assure quick heating of the mixture and even to assure regeneration of heat, when the process 30 has to be economically sustainable.

Also filtration equipment, on which continuous operation of the whole equipment depends, represents great problem. Non-hydrolysed fractions may form suspensions with poor filtrability .

Some procedures use multistage hydrolysis utilising

hydrochloric acid of different concentrations.

Further on we give short review of hydrolytic and dehydration procedures.

- Production of furfuralaldehyde by discontinuous hydrolysis of lignocellulose by sulphuric acid (5% water solution) at the temperature 145-170 °C.

- Similar system of production of furfuralaldehyde from leafy wood. Chips are mixed with acid in worm type apparatus . - Water extract of superphosphate (containing 45% of P205) , which is added directly into the autoclave is utilised in catalytic dehydration in the production of furane from furfuralaldehyde "

- Continuous hydrolysis is known, using single stage expansion only and raw material is impregnated by sulphuric acid before hydrolysis.

Common shortage of all above mentioned procedure of obtaining of furfural and other components is low yield of the final product, which in operational conditions does not exceed 30 to 45 % of the theoretical value and insufficient utilisation of some components of raw materials used.

Vhen using fluid procedure decrease in yields is caused also by thermooxidising decomposition of furfuralaldehyde in reaction with air oxygen. Oxygen flows into the reaction space in chamber method during dosing.

Patents and laboratory systems of the Stake

Technology company, Forintek consider prehydrolysis of cellulose and consequently with cellulose hydrolysis.

Prehydrolysis does not fulfil its expected function of hemicellulose decomposition and transition to so called pure fraction, to the second stage of lignin and cellulose. In the second phase of cellulose hydrolysis remnants of cellulose exist in range, causing inhibition of consequent fermentation procedures.

Current known methods of hydrolysis of

lignocellulose materials are demanding from the point of view of energy consumption, do not cover complex effective and optimal separation of products arising in hydrolysis or at low energy consumption give rise to high costs of regeneration of acids.

The substance of the invention.

Above mentioned disadvantages of given methods of hydrolysis procedures of production of furfural, or furane eventually, cellulose or glucose eventually and pure lignin are solved and removed by the method of continuous pressure hydrolysis of lignocellulose materials, in presence of inorganic acid if need be, with subsequent expansion and separation of hydrolysate and gaseous phase, according the invention. The substance of the invention consists mainly in moisturising of disintegrated raw material at pressure and heating it by pressure water of temperature 170 to 200 °C at the ratio of water to dry substance 0.5 to 1:1. For the mixture obtained excessive water is pressed off to the ratio of water to dry matter 1:0.3 to 0.5. Consequently with simultaneous feeding of pressure water at the temperature 170 to 200 °C at the ratio to dry matter 1:2.5 to 4 mixture is hydrolysed at the temperature 160 to 230 °C and pressure 0.6 to 2.8 MPa for the period of 3 to 18 minutes, while hydrolysis proceeds with simultaneous steady process of solid and gaseous phases. After termination of hydrolysis the material is expanded in two stages giving rise to gaseous phase and hydrolysate. Gaseous phase contains furfural, methanol and lower organic acids, hydrolysate contains cellulose, lignin and water. Gaseous phase is rectified and it is separated to furfural mixture and mixture of acetic acid, formic acid and water. Water is removed from the hydrolysate by pressing and solid remnant is extracted for 10 to 35 minutes by the solvent

formed by ethanol or acetone. Lignin is transferred to the solvent, cellulose remains in the solid phase.

Simultaneously with the feed of pressure water to the hydrolysis process at the ratio to dry substance 1:2.5 to 4 it is possible to dose sulphuric acid at the amount 0.1 to 0.3 % of the mass of sulphuric acid in respect to the mass of suspension, after hydrolysis the hydrolysate obtained, containing sugars and lignin and fraction of non-hydrolysed cellulose and water are pressed, solution containing sugars is separated and the solid remnant is further on treated by extraction or it returns back to hydrolysis. Solution containing sugar may be processed further by fermentation method to ethanol . Furfural mixture is distilled and pure furfural is treated by sodium hydroxide. Arising salt of furoic acid is melted at the temperature 200 to 240 °C to furane or catalysts at the temperature 350 to 430 °C act on furane . The first expansion proceeds with advantage at the temperature 130 to 170 °C and the pressure 0.25 to 0.9 MPa and the second expansion proceeds at the temperature 105 to 120 °C and the pressure 0.12 to 0.2 MPa.

Overall heating of raw materials is provided by pressure water and preheating of all recirculated non-hydrolysed material is provided by expansion steam and after that directly by the pressure water.

The equipment consists of the reservoir of raw material , which is via feeding press of worm type and insert connected with the first section of the hydrolyser, where worm conveyor is situated. Output from the last section of the hydrolyser is equipped by high-pressure expansion slide valve, which is followed by middle-pressure expander and low-pressure expander. In the upper part of the expanders the second and third tubing for outlet of the gaseous phase are located, the second tubing for outlet from the middle pressure

expander is directed to the system of recuperation exchangers with its mouth in the upper part of the rectification column. In the upper part of the column exhaust of furfural and methanol and in the bottom part exhaust of the mixture of formic acid, acetic acid and water are located. The third tubing for outlet of the vapour phase from the low-pressure expander may pass through the lower part of the rectification column and it leads in the middle part of the rectification column. The lower part of the middle-pressure expander is connected via middle-pressure slide valve with the first tubing for hydrolysate and solid phase with the low-pressure expander. This expander is connected via low-pressure expansion slide valve by the fourth tubing for hydrolysate and solid phase with the reservoir for hydrolysate and solid phase, from which outlet of vapours is directed to the rectification column. The reservoir for hydrolysate and solid phase is via pump connected with the separation equipment. The separation equipment is provided by the fifth tubing for outlet of the liquid hydrolysate to the reservoir of hydrolysate and by conveyor for output of the solid phase after hydrolysis, which is connected to extractor and reservoir of the raw material . Filling press consists of the cylindrical part and conical part. A worm with constant lead in the cylindrical part and with decreasing lead in the conical part goes through both parts of the press, while the conical part consists of segments, among which are gaps for outlet of the liquid to the reservoir of liquid, the conical part is provided inside by longitudinal guide bars, the front face of the cylindrical part is perforated .

The insert is tightly connected with the filling press and it leads to the first section of the hydrolyser and it consists of input conical narrowing part. cylindrical part and conical widening part.

Opposite the outlet of the conical widening part safety closing piston, controlled by adjustable pressure is situated .

The expanders have the form of cyclone separators and the outlet of hydrolyser enters tangentially the middle-pressure expander and the first tubing 10 for hydrolysate and solid phase enters tangentially the low-pressure expander. The second and third tubes for outlet of the vapour phase from expanders are recessed to the upper parts of expander below the level of the mouth of the outlet from the hydrolyser and the first tubing for hydrolysate and solid phase. In the bottom part of the middle-pressure expander middle-pressure expansion slide valve is situated and in the bottom part of the low-pressure expander low-pressure expansion slide valve is situated.

The hydrolyser consists of at least one section, sections are connected by vertical tube or by widening cone. All sections are provided by exhaust of inert gases and worm conveyor passes through all sections.

In the reservoir for raw material the material is preheated to the temperature of 85 to 90 °C by feed of small amount of technological pressure water of the temperature 170 to 200 °C, which acts thanks to its expansion very intensively on the material. Moistened preheated material is relieved of excessive moisture in the conical part of the filling press, which is equipped by effective dewatering system, which reliably removes the excessive liquid, which represents great problem for most current equipment. The filling press presses material into the insert, in which it forms compact plug. Its purpose is to separate atmospheric medium of the filling press from the high-pressure medium in the hydrolyser. In this model the insert is in addition in contrast to all known solutions provided by conical widening part, which substantially improves the main function of the plug, i .e. safe separation of the

pressure chamber in the hydrolyser from the surroundings. In the hydrolyser the material is mixed with pressure water in the ratio of dry matter to water 1:2.5 to 1:4. Water may contain sulphuric acid in the amount of 0.1 to 0.3 % mass related to the suspension mass .

Concentrated sulphuric acid is mixed with water to the concentration 0.2 to 0.4% mass, before feeding into the hydrolyser in such way, that into the hydrolyser diluted solution with minimal corrosive effects is added. Mixture of water and material moves on through the equipment due to rotation of worm conveyor and substantially by plug flow. From the upper part of the hydrolyser inert gases are continuously removed trough exhaust. Material falls into other sections of the hydrolyser through the vertical widening tube. At the end of the last section the decomposed material is squeezed out into high-pressure expansion slide valve, from which the expanded mixture is displaced into the middle pressure-expander, where the temperature is in the range 130 to 175 °C and pressure is in the range 0,25 to 0,9 MPa. Here expander in the form of cyclone separator is utilised with great advantage. The material is brought in tangentially to the cylindrical part. The hydrolysate and solid phase expand further in the low-pressure expander to the temperature 105 to 120 °C and pressure 0,12 to 0,20 MPa. Expander functions on the same principle of the cyclone separator. The last vapour fraction is released from the hydrolysate in the reservoir of hydrolysate and solid phase, from which the liquid is pumped together with the solid phase into separator, where solid phase is separated, which consists of lignin and cellulose, from the liquid hydrolysate. Due to the rotation flow perfect separation of the solid phase and hydrolysate from the vapour phase occurs. The hydrolysate contains 0,1 mass% of furfural at maximum and in the same time faultless outlet of the

solid phase from expander is guaranteed.

The main advantage of the equipment is high energetic efficiency, which is enabled by double expansion. Vapour leaves the middle-pressure expander at the temperature 130 to 170 °C. This vapour is used in the system of recuperation exchangers for preheating of fresh technologic water to the temperature 125 to 165 °C, so the pressure boiler gives heat only for heating to the temperature of hydrolysis. Other substantial saving of heat results from usage of vapour in the low-pressure expander for heating in the boiler of the rectification column. Double expansion has also the advantage of perfect exhaust of furfural from hydrolysed solution, where its presence is undesirable due to consequent fermentation. The vapour phase from expanders is separated in the rectification column to furfural and methanol and to water solution of inorganic acids. Furfural may be further purified in distillation column, it is obtained in high purity and yielding, 60% related to original pentosanes in the hydrolysed material. Furfural maybe processed further to furane.

Low consumption of water belongs among other advantages of this method and equipment. It is due to the fact, that all recycled water and recycled hydrolysate are heated to temperature needed for hydrolysis in the system of recuperation exchangers and by direct heating by pressure water; in this way problem of encrustation of sugars on the walls at high temperatures is eliminated.

The advantage of the method and equipment according to the invention is, that the production process is:

- continuous - single staged

- the equipment is capable to process wide range of types of input raw materials

- continuous exhaust of inert gases

- hydrolysate containing sugar does not contain inhibitors of fermentation processes

- 90 to 100% splitting of input lignocellulose - shorter time for extraction of lignin that in other currently known procedures

- production of pure products: cellulose, glucose eventually, lignin, furfural, furane, acetic acid, formic acid, methanol, ethanol - high yielding of individual products, yielding of furfural is 48 to 60%, of cellulose 95% of input cellulose, of glucose 65% related to input cellulose, of lignin 80 to 90% of input raw material related to wheat straw - production of highly reactive lignin

- equipment is provided by fluent dosing of input raw materials

- variability of temperatures in the range from 160 to 230 °C - building-block system of main equipment of the line

- optimisation for all types of raw material

- fluent expansion

- safety of the system

Review of pictures:

Fig. 1 is the scheme of the whole equipment for hydrolysis .

Fig.2 shows the filling press 51. Fig.3 shows the insert 52.

Fig.4 Shows the scheme of the equipment for production of furane from furfural via furoic acid.

Fig. 5 shows the scheme of the equipment for direct production of furane from furfural.

Examples of application of the method.

The disintegrated straw is moistened and heated by pressure water of temperature 200 °C in the ratio of water to the dry matter 0.8:1 to the temperature of 90 °C. From obtained mixture the excessive water is removed by pressing to the ratio of dry matter to water 1:0.4 and consequently it is hydrolysed at the temperature 200 °C and corresponding pressure for 8 minutes under simultaneous feed of pressure water of the temperature 200 °C in the ratio to the dry matter 1:3.5. The hydrolysis proceeds with uniform steady process of solid and liquid phases. After termination of hydrolysis the material is expanded in two stages giving rise to vapour phase and hydrolysate. The vapour phase contains furfural, methanol and lower organic acids, the hydrolysate contains cellulose, lignin and water. The vapour phase is rectified and separated to furfural mixture and mixture of acetic and formic acids and water. Water is removed from the hydrolysate by pressing and the solid remnant undergoes extraction by acetone for 30 minutes. Into the acetone phase lignin is extracted and after evaporation of the solvent reactive lignin is obtained, cellulose remains in the solid phase .

Wheat straw contained 480 kg of cellulose, 270 kg of pentosanes and 130 kg of lignin related to 1000 kg of dry matter. Using procedure according the invention 456 kg of pure cellulose was obtained, which represents 95 % yielding, 100 kg of furfural, which is 53% yielding and 117 kg of pure lignin, which is 80% yielding. Furfural was further processed to furane. Yielding of furane in respect to furfural was 60% using the direct method, via furoic acid it was 50%.

Example 2

Using the same procedure as in example 1 maize spindles and beech fillings were processed. In case of

maize spindles yielding of cellulose was 85%, of furfural 51% and of lignin 80%. In case of beech fillings yielding of cellulose was 85%, of furfural 50% and of lignin 80%.

Example 3

All these raw materials were processed by similar procedure as in example 1 but material , entering hydrolysis was simultaneously wetted by pressure water with 0.2% mass, of sulphuric acid related to the mass of the suspension. The ratio of water to dry matter was 1:4. The first expansion was made at the temperature 160 °C and the second expansion at the temperature 105 °C. Hydrolysate obtained after hydrolysis, containing sugar and lignin, and fraction of non-hydrolysed cellulose and water was pressed, solution containing sugar was separated and solid remnant was further treated by extraction. From the sugar containing solution ethanol was produced by fermentation procedure in yield 60% related to glucose.

In case of wheat straw instead of cellulose glucose was obtained in the yield 65% with respect to original content of cellulose in straw, in case of maize spindle and beech fillings it was 57%.

Example 4

Description of equipment on individual figures and its function. The scheme of whole equipment for hydrolysis is shown in figure 1.

The equipment consists of the reservoir 5_0 of raw material, which is via the filling worm press 5_1_ and the insert 5_2 connected with the first section of the hydrolyser 5_3, where the worm conveyer 5_4 is situated. The filling worm press 5J, is connected with the reservoir 6_7 for liquid removed by pressing. The

reservoir 5_0 of raw materials and hydrolyser 5_3 are equipped by feed of pressure water from the boi ler 6 .

The hydrolyser 5 consists of three sections, sections are connected by vertical tube or by widening cone. Outlet from the last section of the hydrolyser 5_3 is equipped by the worm equipment 6_8 and the high-pressure expansion slide valve 5_5 , which is followed by the middle-pressure expander 5_6 , which followed by the low-pressure expander 5_7_. Al l sections of the hydrolyser 5_3 are provided with the exhaust 6 of inert gases.

The expanders 5_6 and 5_7 have the form of cyclone separators and the outlet £ from the hydrolyser 5_3 enters tangentially into the middle-pressure expander 5_6. The first tubing 1. for hydrolysate and solid phase enters tangentially the low-pressure expander 57. The second tube 2 and third tube 3_ for outlet of vapour phase from the expanders 5_6_ and 5_7 are embedded in to the upper parts of expanders 5_6 and 5_7 under the level of the mouth of the output £ from the hydrolyser 5_3 and the first tubing 1_ for hydrolysate and solid phase. In the bottom part of the middle-pressure expander 5_6 middle-pressure expansion slide valve 6) is situated and in the bottom part of the low-pressure expander 5_7 low-pressure expansion slide valve 6_1_ is situated.

The second tubing 2 for outlet of the vapour phase from the middle-pressure expander 5_6 is directed to the system of recuperation exchangers 5_8 and it is connected with the upper part of the rectification column 5_9 , in the upper part of which the outlet 1_ of furfural and methanol is situated and in the bottom part the outlet of mixture of acetic acid, formic acid and water is situated. The third tubing _. 3 for outlet of the vapour phase from the low pressure expander 5_7 goes through the bottom part of the rectifica ion column 5_9 and has its mouth in the middle part of the rectification column 59. The bottom part of the middle-pressure expander 5_6

is connected via middle-pressure expansion slide valve 60 by the first tubing 1 for hydrolysate and solid phase with the low-pressure expander 57. Expander 57 is connected via low-pressure expansion slide valve 6J_ by the forth tubing 4_ for hydrolysate and solid phase by the reservoir 6_2 for hydrolysate and solid phase which is via the pump 63 connected with the separation equipment 6_4. Separation equipment 6_4 is provided by the fifth tubing 5. for outlet of liquid hydrolysate to the reservoir 6_5 and by the conveyor i for outlet of the solid phase after hydrolysis, which is connected with the extractor 6_6 or with the reservoir .5(3 for the raw material .

Exhaust 2 of furfural and methanol is connected with the purification block of furfural .

Figure 2 shows the filling press 51_ , which consists of the cylindrical part 3_i and conical part 3_2. The worm 33 with constant lead in the cylindrical part 3_1 and with decreasing lead in the conical part 3_2 passes through both parts, while the conical part 3_2 consists of segments .3_4 among which there are gaps 3_5 for outlet of liquid into the reservoir 6_7 for liquid removed by press, the conical part 3_2 is inside equipped by longitudinal guide bars 3_6_, the front face 3_7 of the cylindrical parts 3_1_ is perforated.

The insert 5.2 is shown in the figure 3. It is tightly connected with the filling press 51_ and it leads into the first section of the hydrolyser 5_3. It consists of inlet conical narrowing part 3_8, the cylindrical part 39 and the conical widening part 4_0. Opposite to the outlet of the conical widening part 4O the safety closing piston 4± , controlled by adjustable pressure is located .

The scheme of equipment for production of furane

from furfural via furoic acid is shown in figure 4.

The equipment consists of the furfural reservoir 22 _. which is via the first exchanger 7_2 connected with the first vessel 7_3, which is connected with the reservoir 7_5 of sodium hydroxide and with the second vessel 76 , which is followed by the third vessel 7_7. All 3 vessels are equipped by stirrers and cooling. The third vessel 77 is connected with extraction column 74 _* which is connected with the forth vessel ΣH) for removal of water from ether extract, which is connected with the reservoir 7_9 of magnesium sulphate and with the first drum filter 81.

Filter is followed by the conveyer 8_2 and by the annealing furnace 8_3 for magnesium sulphate. The annealing furnace is via the second exchanger 8_4 connected with the ether reservoir 7_8 and with the reservoir 7_9 of magnesium sulphate.

The first drum filter 8J_ is connected via the reservoir 8.5 of semi-product with the distillation column 8.6. The upper plate of the column £6_ is connected with the reservoir 23 _. of ether and bottom plates are connected with the reservoir 8_7 of 2-furfuralalcohol . The bottom part of the extraction column 7_4 is connected via the fifth vessel 8_8 with the crystal1i sator 90 , which is provided by cooling. The crystal 1isator £0 is connected to the sixth vessel 1_, which is connected via the conveyor £2 with the reservoir £3. of activated carbon, the sixth vessel £1_ is via the second drum filter £4 and the third exchanger £5 and other third drum filter £6 connected with the reservoir £7 of furoic acid. This reservoir is via the third conveyor £8 connected with the melting furnace ££, which is followed by the reservoir 100 of furane.

Fig. 5 shows the scheme of direct production of furane from furfural, which consists of reservoir of

furfural 2_L. which is followed by the pressure melting furnace 101. which is via the exchanger 102 connected with the reservoir of furane 103. The pressure melting furnace 101 is further connected with burning chamber 104.

Vegetable raw material is dosed via continuous balance to the reservoir of raw material 5j0, from which it is swept out by worm _5_2 to the fi lling press 51 , where in the front cylindrical part 3 i t is preheated by pressure water or steam to about 90 °C. The filling press 5 presses the material via narrowed insert 5_2 into the hydrolyser 5_3. Liquid removed by pressing in the filling press 5J_ flows to the reservoir 6_7 of the removed liquid, from which it is pumped back to the feed of the filling press 5.1. In the insert _5_2 compact plug is formed, which separates the hydrolyser from the view of pressure. Compactness and impermeability of the plug is assured by the safety piston 4 . Material entering the first section of the hydrolyser 5_3 is wetted from above by pressure water of the temperature 170 to 200°C, eventually by sulphuric acid, in case when decomposition of cellulose is the purpose. Material is uniformly moved forward by the worm conveyor _5_4 with liquid in the hydrolyser 5_3 at the temperature 160 to 230 °C at the pressure 0.6 to 2.8 Mpa.

The whole time of retention (delay) of material and liquid is the same, i.e. from 3 to 12 minutes. At the end of the section material with the liquid falls into the next section of the hydrolyser 53. All sections of the hydrolyser 5_3 work at the same pressure. From the upper part inert gases are removed continuously by the exhaust 6_. From the last section of the hydrolyser 5_3 material and liquid are swept out by the worm equipment 6_8 into the high-pressure slide valve 5_5, behind which the mixture is expanded to middle pressure 0.25 to 0.9 MPa and temperature from 130 to 175 °C. In the

middle-pressure expander 5_6 vapor phase is separated. Its heat content is utilised in the system of recuperation exchangers 5_8 for pre-heating of technological water. The condensed vapour phase is brought into the rectification column 5_9. Liquid and solid phases from the middle-pressure expander ^6 are directed via middle-pressure expansion slide valve 6_0 to the low-pressure expander 5_ , in which the temperature is in the range 105 to 120 °C and pressure 0.12 to 0.2 MPa. The released vapour is used for heating in the boiler of the rectification column 5_£. Liquid and solid phase is removed via low-pressure expansion slide valve 61 to the reservoir 6.2 for hydrolysate and solid phase. From this reservoir released vapour phase is also directed into the rectification column 5_£. Liquid and solid phases proceed into the separator 6_4, where they are separated to solid phase, which consists mostly of lignin and non-reacted cellulose. Both substance are separated in the extractor 66. Liquid hydrolysate with monosacharides is removed in case of acidic hydrolysis via the reservoir 6_5 for further treatment e.g. for fermentation. Liquid hydrolysate contains in case of acidic hydrolysis 12 to 15% mass, of glucose and it is further processed e.g. to ethanol .

In case of acidic hydrolysis part of solid phase, which has not reacted and contains first of all cellulose. is recycled and it forms feed to the hydrolyser 5_3. In case when the hydrolysis is carried out only by steam, liquid hydrolysate is pre-heated in the system of recuperation exchanger 5_8 and it is returned to the hydrolyser 5_3. What is substantial , is, that no recirculated solution does not pass through the pressure boiler 6£, but it is heated to the necessary temperature by pressure water, produced by heating of fresh technological water in the pressure boiler 69.

In the head of the rectification column 5£ exhaust

2 o furfural and methanol is situated. In the bottom part exhaust 8. of mixture of acetic acid, formic acid and water is situated.

Furfural fraction is further purified by distillation and it is collected in the reservoir 21 of furfural .

From the reservoir of furfural 22 _. in figire 4 furfural cooled in the first exchanger 12 _. to temperature 5 to 8 °C is pumped to the first vessel 7 • Into this vessel sodium hydroxide is dosed from the reservoir 75. Salt of furoic acid and 2-furfuralalcohol are formed by reaction with hydroxide. The time of delay of mixture in the first vessel 73 is about 20 minutes. The temperature may not exceed 20 °C. Mixture is then moved due to self-slant to the second stirred vessel 7_6, where the reaction terminates. Time of delay in the second vessel 76 is about 60 minutes. Also this second vessel 76. has to be intensively cooled. Mixture is moved by self-slant to the third vessel 22. which is also cooled. Due to cooling crystals of the salt of furoic acid are separated out and they form precipitate, which is eliminated by addition of water. From this vessel mixture is moved by pumping to the extraction column 74 , where continuous extraction of 2-furfuralalcohol by ether occurs. Ether is pumped from the reservoir 78.

Water is removed from the extracted 2-furfuralalcohol with ether and casual impurities by addition of dehydrated magnesium sulphate MgS04 , which is stored in the reservoir 2£ of magnesium sulphate. Mixing is carried out in the fourth vessel £$0 _. . Magnesium sulphate absorbs water and creates hydrate MgS04.7H20, which crystallises. These crystals are removed in the first drum filter 82. and they are transported by the first conveyor 8J2 into the annealing furnace 83_, where sulphate is regenerated. The furnace 8_3 is blown through by air and ether vapours are removed, which are further on condensed in the second exchanger J^4 and return to

the ether reservoir 2ϋ• Water from hydrate MgS04 is then removed by roasting, regenerated magnesium sulphate is returned by conveyor to the reservoir 7 .

Filtrate from the first drum filter 82. is removed to the reservoir of semi -product 8 .. This mixture contains only 2-furfuralalcohol and ether, impurities ( water, magnesium sulphate, furoic acid) eventually. This mixture is pumped into vacuum distillation column 86. From the upper plate ether is removed, which is directed back to the reservoir 28 and from the bottom plate 2-furfuralalcohol is removed, which is stored in the 2-furfuralalcohol reservoir 87.

The second steam, leaving the extraction column 74 , contains sodium salt of furoic acid. Conversion to furoic acid proceeds by acidification in the fifth vessel £18. By cooling in the crystalliser £0 crystals of furoic acid are precipitated and sodium hydrogensulphate (according to pH precipitation of sulphate may occur) . After separation of these two substances it is necessary at first to suck away excessive water. This is done in the crystallisator £0_. Then the mixture is boiled with activated carbon in the sixth vessel £2. Activated carbon is dosed by the second conveyor of activated carbon £2 from the reservoir of activated carbon 93. Boiling lasts for about 45 minutes. Activated carbon is then removed from the mixture on the second filter £4 and is regenerated in simple way by blowing-through by air in the reservoir of activated carbon 93.

Filtrate is transported by pump via the fourth exchanger £5. to the third drum filter £6_. In the fourth exchanger £5 the mixture is cooled to the temperature 16 to 20 °C (below the temperature 10 °C even the rest of hydrogen sulphate is separated out and above the temperature 20 °C crystallisation is not sufficiently intensive) . Crystals separated out are then removed on the third filter £6. Filtrate, containing water solution of hydrogensulphate, or sulphate respectively, leaves

for the sodium sulphate reservoir. Crystals of furoic acid are stored in the reservoir of furoic acid £2 and from there they are dosed by the third conveyor £8 to the furnace ££, where melting of the acid at the temperature 230 °C occurs. In this process carbon dioxide is intensively separated out, which is separated after cooling of furane. Due to high volatility it is necessary to keep furane at low temperature and in closed vessel 100. From the reservoir 21 (fig- 5) furfural is dosed to the pressure melting furnace 101. where catalyst (CaO, CaCO^ , MnCr0 ₂ or ZnCrθ2) is added. After closure the pressure melting furnace 101 is heated to the temperature 400 °C. Furane is separated out and it is cooled and stored in the furane reservoir 103. Considerable amount of carbon oxide also leaves the pressure melting furnace 101. It is necessary to destroy it safely by burning in the burning chamber 104. This production process cannot be carried our continuously because of high temperature and pressure, at which the reaction in pressure melting furnace 101 occurs.

Industrial application

The invention may be utilised for complex and effective processing of sources of phyto ass sources as new perspective sources of non-fossil raw materials in the tight bond to chemical , pharmaceutical and food industries .