JPS58101703A - Post-treatment method and apparatus of used decomposing liquid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves post-processing the used decomposition liquid produced when cellulose-containing plant materials are decomposed with an organic solvent under high temperature and pressure, and at that time subjecting the decomposition liquid to flash evaporation. , relates to a method for post-treatment of used decomposition liquid and an apparatus for implementing this method.

Various methods are already known for decomposing cellulose-containing plant materials with organic solvents.

According to U.S. Pat. No. 3,585,104 and German Patent No. 2,644,155, vegetable fiber materials are prepared in a countercurrent manner in a mixture of water and an organic solvent (e.g. ethanol). It is treated under high pressure at a temperature of 150-200C. Work-up of the spent decomposition liquor is carried out by multi-stage flash evaporation, during which volatile organic components are separated. The residual liquid containing all dissolved components is separated into an aqueous phase containing monomeric sugars, oligosaccharides, organic acids, etc. and a dark brown substance in a semi-molten state consisting of a plastic lignin material.

Canadian Patent No. 238.294 discloses carrying out this so-called "Organsotv" process in a batchwise operation in a set of pressurized vessels. In this case, the pressure of the used decomposition liquid is released in advance by equilibrium flash evaporation, and then subjected to stripping treatment under reduced pressure.
In this case, two phases similar to those described above also occur.

According to Yoshirotsupa Patent Application No. 12960, similarly, a plant fiber material is extracted with an organic solvent in a reactor continuously operated at high temperature and pressure. The liquid passes through a cooler and is delivered to a waste pressure relief vessel. In this case, the lignin also precipitates as a heavy second phase and must be separated.

German Patent Application No. 2,920,731 proposes decomposition with organic solvents at 190-200 C with the addition of suitable catalysts, in particular mineral salts. Work-up of the chemicals takes place by separating the lignin phase from the aqueous solution again after flash evaporation of the decomposition solution.

In both of these cases, some burdensome difficulties arise in the recovery of the spent decomposition liquid after-treatment, such as the recovery of the used decomposition liquid or solvent, namely the pressure relief and the subsequent cooling of the used decomposition liquid. In this case, the lignin decomposition products form the plastic phase mentioned at the beginning. However, this is a very sticky, thick, tar-like product that significantly impedes transport through conduits, fittings, and pumps.

Furthermore, this viscous precipitate contains a large amount of solvent, which can no longer be removed by heating the lignin phase to its boiling point, so that the recovery rate of the decomposition agent is poor and uneconomical. The post-treatment of this plastic layer poses problems. The aqueous layer that results in both of the above-mentioned methods has large amounts of other contained substances that do not allow direct guidance of this aqueous solution to the drain. ing. For example, in the past, the aqueous layer had to be subjected to a separate aftertreatment in an additional process step.

The heat content of the decomposition liquid provides about 1/4 to 1/4 of the energy required to evaporate all volatile components, depending on the composition of the decomposition liquid.

The problem of the present invention is to deal with used parts. A method for overcoming the above-mentioned difficulties and drawbacks in the after-treatment of dissolution fluids and in order to carry out the after-treatment without interference with an optimum recovery of the solvent used and at the same time improving the energy balance, and for carrying out the method. The goal is to find a device for this purpose.

This task was achieved in accordance with the invention in a process of the kind specified at the outset, in which the volatile components of the decomposition liquor were completely removed and fractionated by distillation in one stage of 7-lush evaporation under the supply of heat, and the non-vaporizable residue was solidified. Solved by getting in state.

A particular advantage of the process of the invention is that the solvent is virtually completely recovered in a single stage and the lignin decomposition products are produced in a solid state that can be easily handled.

The spent decomposition liquid is kept under decomposition treatment conditions - i.e. at a temperature of 150 to 210C - until the point of flash evaporation;
Avoid sedimentation and blockage of conduits, fittings and pumps.

The method of the invention is suitable for after-treatment of decomposition liquors from any cellulose production plant operating on the basis of extraction with organic solvents.

In this case, the cellulose production equipment may be designed for continuous or discontinuous or batch processes.

According to an advantageous embodiment of the process of the invention, the heat supply is carried out above the softening point of the non-evaporable residue and above 1300, in particular above 1
In this way, entrapment of the solvent in the non-evaporable residue, which is carried out by means of a heating surface heated to a temperature of 50 to 160° C., which essentially consists of lignin decomposition products, is reliably avoided.

According to another advantageous embodiment, the heat supply is between 200 and 270
This is carried out with a gaseous heating medium at a temperature of C, preferably using overheated steam of the decomposition liquid as the heating medium.

Appropriate equipment for carrying out the method of the invention is:
It has a thin film evaporator and a rectification column, and is equipped with a flash nozzle for introducing the spent cracking liquid into the top of the thin film evaporator, which has the following characteristics: - The upper part of the evaporator a heating jacket at the top and a cooling jacket at the bottom; - from the top of the evaporator the vapor conduit is guided, possibly through an eliminator, to the rectification column; - through the evaporator. The heatable rotary shaft has a scraping element in the upper part of the evaporator and a scraping element in the lower part and is provided with solids removal means in the lower part of the evaporator.

Another suitable device comprising a spray dryer and a rectification column has the following characteristics: one or more spray nozzles are installed in the lower part of the drying chamber of the dryer towards the top; The supply conduit for the gaseous heating medium terminates tangentially in the upper part of the dryer, and - the interior space of the drying chamber is optionally accessed via a steam conduit emerging from its lower part. It is connected to a rectification tower with a cyclone in between.

A steam conduit is connected to the cyclone, and from the upper part of the cyclone, the steam from which solids have been removed is guided by a steam fan to the steam conduit, which is passed through a control valve to the rectification column on the one hand, and On the other hand, it is advantageously connected through a heat exchanger to a supply line for the gaseous heating medium.

The drawings serve to illustrate the invention. FIG. 1 shows an apparatus according to the invention equipped with a thin-film evaporator and a rectification column, and FIG. 2 shows an apparatus in which the overheated vapor of the cracking liquid is fed as a heating medium to a spray dryer. The apparatus is then shown in which another portion of the vapor is conducted to a rectification column.

In FIG. 1, a thin film evaporator is generally indicated by (1), and a flash nozzle (2) is attached to the tip of the evaporator for introducing the used decomposition liquid. The upper part of the cylindrical evaporator is surrounded by a heating jacket (3) with couplings (4, 5) for the supply and removal of the heating medium.

The rotary shaft tilt extending axially through the evaporator can be heated via the connection terminal (7t8). The lower part of the evaporator has a joint (1o) for supplying and discharging the cooling medium.

The rotating shaft, which is surrounded by a heating jacket (9) with a heating jacket (11), is seated in bearings (12, 12') and is operated in the illustrated embodiment by a bevel gear (1).
3) and (14) of the heating jacket, in the region of the upper part of the evaporator surrounded by ) of the heating jacket, the rotating shaft carries abrasion elements (15) for separating or spreading the liquid film flowing down. And in the area at the bottom of the evaporator surrounded by the cooling jacket, non-evaporable solids escape from the evaporator wall! !
□It has a scraping element (16) for removing residue. The residue is discharged from the lower part of the evaporator through a multi-lobe wheel system (17) onto a schematically illustrated conveyor belt (1B).

From the top of the evaporator, a steam conduit (19) is further guided through an eliminator (20) to a rectified percentage (21),
The bottom of the column can be heated by a heat exchanger (22). The distillate product - primarily water - is drawn off through a partial overflow means (23). The organic solvent vapor generated at the top of the column is transferred to a heat exchanger (2
4) to cool and condense. The desired reflux ratio is adjusted by a 3-way magnetic valve (25) and the top product is withdrawn from conduit (26).

The spent cracking liquor is fed directly from the extractor or reactor to the flash nozzle (2) and is depressurized, for example to atmospheric pressure, in the illustrated evaporator (1).

The liquid flowing down the walls of the evaporator is maintained at a temperature above the softening point of the non-evaporable residue (lignin decomposition product), that is, above 130C, by a heating jacket in the upper part. All other components are completely evaporated, and finally the lignin component reaches the molten state in the lower part of the evaporator surrounded by a cooling jacket, where it becomes solid and brittle under cooling. This residue is removed by the scraping element (16) and the multi-layer wheeled gate (
17) and carry it out.

The vapor containing organic solvents, water, organic acids, fluorine, etc. is separated into these components in a rectification column (21).

When ethanol is used as the organic solvent, it has surprisingly been found that the amount recovered is 100.5 to 102 times the amount of ethanol used. In order to elucidate this surprising result, we mixed beech wood chips with 45 parts of alcohol and 55 parts of alcohol.
% of water under pressure for 4 hours at 180C.

The spent digestion fluid is then poured into a second autoclave and cooled to room temperature. 0.3 by gas chromatograph method
% ethanol can be observed. Therefore, the observed 1
The ethanol recovery rate of more than 0.00% can be explained by the production of ethanol during the extraction process.

The solid residue obtained can be directly combusted to obtain energy or can be further worked up with its containing substances.

In the apparatus according to FIG. 2, the drying chamber of the spray dryer is (27)
is shown. At the bottom of this chamber is a spray nozzle (28).
is installed, whereby the spent decomposition liquid is ejected vertically under pressure relief into the top of the dryer, where the droplets flow tangentially through the supply conduit (29). encounters the gaseous heating medium injected from the
During this process, volatile components evaporate.

In the illustrated embodiment, overheated steam of the decomposition liquid is used as the heat transfer medium. This steam is first transferred to a drying chamber (27
), it reaches a cyclone (31) through a steam conduit (30) emerging from the lower part of the solid residue, where the pulverulent component of the solid residue is separated off and discharged through a multi-wheeled gourd (32). Steam is supplied from the upper part of the cyclone (31) by a steam fan (33) to a steam conduit (34), from which a portion of the steam is passed through a control valve (35) and again through a supply conduit (29). A drying chamber (2
7), the steam is heated by a heat exchanger to a temperature of approximately 200-270C before reaching conduit (29).

The other part of the steam from the steam conduit (34) is supplied by one control valve (
37) to the rectification column generally shown in (21). The individual parts of the rectification column are as shown in FIG.

The non-evaporable residue which forms in the solid state in the drying chamber (27) of the spray dryer is conveyed off through a multilayer wheel gate (38) and together with the dust powder components from the gate (32) to the schematically indicated belt conveyor (32). 39) Reach the top.

In the case of the apparatus shown in Figure 2, the used decomposition liquid (
(not shown) extractor or reactor, directly into the spray nozzle (28) without prepressure relief or cooling.
from which the liquid is sprayed, for example under near atmospheric pressure, into a drying chamber (27).

Energy supply in the form of heated air is unsuitable, since instead of the vapor of the recycled and superheated decomposition liquid, for example superheated steam may be sprayed as heating medium.

This is because difficulties arise in this case both in explosion prevention and in the direct rectification of the vapors.

The present invention will be explained in more detail by the following examples.

Example 1: Beechwood cuttings are decomposed and extracted in a mixture of 1% ss alcohol and 45% water in a pressurized reactor at 195C for 4.5 hours.

The decomposition liquid is then poured into a second heated autoclave and mixed several times with a fresh alcohol/water mixture, thereby removing any adhering lignin residues from the cellulose. - Used as a decomposition liquid.

The spent decomposition liquid is fed to the flash nozzle G of the thin film evaporator of the apparatus according to the invention in FIG. Thin film evaporators (thin film evaporators) operate under standard pressure.

The heating jacket θ) and the rotating shaft (6) are heated to 155C with heating oil.

Heat content of used decomposition liquid (water/ethanol 45155
In this case, when cooling from 195C to 105C, it flows out from the wall at the top of the generator. The residue becomes solid in the lower cooling part of the evaporator, where the cooling jacket is maintained at a temperature of 5 Or by an oil-type temperature control means, and is scraped off with a scraping element (16) and then removed with a multilayer wheel gate (17).
) through the conveyor bell) (18).

The water vapor condenses and decomposes.

Ethanol recovery was 100.0% in 5 parallel experiments.
It is 5 to 102 chi.

The solid residue contains no more than 0.02 g of ethanol; the ethanol content is determined by gas chromatography. The residue is dissolved in geogysan and analyzed. Example 2: The spent decomposition liquid obtained during the decomposition carried out in the same manner as in Example 1 was dried in the spray dryer of the apparatus of the present invention shown in Fig. 2 at 195C and 25 bar. feed the spray nozzle.

The energy supply required for complete vaporization is provided by superheated steam of the decomposition liquid at a temperature of 255C; the ratio of returned steam to spent solution is adjusted to achieve a steam outlet temperature of approximately 105C. , 5.5=1 (theoretical value 4.6
:1), the ratio between the steam returned and the steam achieving the rectification is adjusted by regulating valves (35) and (37).

The non-evaporable residue shows a residual ethanol content of only 0,1-, which is about 0.0 of the total amount of ethanol used.
This corresponds to 25%. Therefore, the ethanol recovery rate is 1o1-.

Comparative example: The used decomposition liquid obtained during decomposition according to Example 1 was 1
The energy for evaporation flows out of the pressurized vessel at 9B5C and is also contained from a flash evaporator with pressure equalization means [for ethanol/water-azeotrope, the evaporation energy is 50 in case of composition with water
4J/g (decomposition liquid), ] can only be completely covered.

In solutions with low ethanol content, a tarry, sticky precipitate containing lignin precipitates.

The ethanol still present in the solution is distilled off by external heat supply.

It can be seen that a large amount of ethanol is contained in the lignin waste, which cannot be removed even by continuous heating of the interlayer mixture. After dissolving the waste in dioxane, a residual ethanol content of 8-11% is confirmed by gas chromatography.

The aqueous solution contains a large amount of components such as hexoses, pentoses, oligosaccharides, organic acids, furfural, phenol-containing compounds, and the like. This requires in each case further process steps, such as evaporation and combustion of the residue.

The degree of contamination of the equipment with tarry waste already makes extensive cleaning work necessary after one experiment.

In contrast to the brittle residues obtained according to the invention according to Examples 1 or 2, the precipitate still containing solvent obtained in this way is a slimy product that is sticky in the cold state. This makes it difficult, if not impossible, to industrially after-process both layers.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing embodiments of the present invention, and symbols in the figures have the following meanings. 1... Thin film evaporator 2... Flash nozzle 3... Heating jacket 6... Rotating shaft 9... Cooling jacket 15 River scraping element 16... Scraping element 17...・Discharge device 19...Steam conduit 20
... Eliminator 21 ... Rectification tower 27 ...
- Drying chamber 28... Spray nozzle 29... Supply conduit 30... Steam conduit 31... Cyclone 33... Steam fan 34... Steam conduit 35
...Control valve 36...Heat exchanger 37...
Control valve 14

Claims (1)

[Claims] (1) Post-processing of the used decomposition liquid produced when cellulose-containing plant materials are decomposed with an organic solvent at high temperature and under high pressure, and at that time, the decomposition liquid is flash-evaporated. In the post-treatment method for used decomposition liquid,
A process as described above, characterized in that the evaporable components of the decomposition liquor are completely removed by one-stage flash evaporation under the supply of heat and fractionated by distillation, and the non-evaporable residue is obtained in a fixed state. 2) The method according to claim 1, wherein the heat is supplied by means of a heating surface heated to a temperature above the softening point of the non-evaporable residue and above 130°, in particular from 150 to 160°C. (3) The method according to claim 1, wherein the heat supply is carried out by a gaseous heating medium at a temperature of 200 to 270C. (4) The method according to claim 3, in which excessive heating and evaporation of the decomposition liquid is used as the heat medium. (5) Spent decomposition, in which the spent decomposition liquid produced when cellulose-containing plant materials are decomposed with an organic solvent under high temperature and pressure is post-treated and the decomposition liquid is subjected to flash evaporation during the coughing process. In the method for post-treatment of the solution,
The above method of completely removing the evaporable components of the decomposition liquid by one-stage flash evaporation while supplying heat and fractionating by distillation to obtain a non-evaporable residue in a solid state is carried out using a thin film evaporator (1).
and a rectification column (21), which is equipped with a flash nozzle for introducing the spent decomposition liquid at the top of the thin-film evaporator (1); - heated at the top of the evaporator; a cooling jacket (3) and a cooling jacket (9) at the bottom, - from the top of the evaporator a vapor conduit (19) is led, if necessary, through an eliminator (20) to a rectification column (21); - a heatable rotary shaft (61) passing through the evaporator has a scraping element (15) in the upper part of the evaporator and a scraping element in the lower part, and - solids removal means in the lower part of the evaporator. (17) The above-mentioned device is characterized by comprising: (6) post-processing of the used decomposition liquid produced when cellulose-containing plant material is decomposed with an organic solvent at high temperature and under high pressure; In a method for post-processing a used decomposition liquid, in which the decomposition liquid is subjected to flash evaporation,
The above method is carried out by using a spray dryer and a rectification column (21) to completely remove the evaporable components of the decomposition liquid by one-stage flash evaporation while supplying heat and to perform distillative fractionation to obtain a non-evaporable residue in a solid state. In an apparatus for carrying out drying, - one or more spray nozzles (28) are installed in the lower part of the drying chamber of the dryer towards the top, - supply conduits (29) for the gaseous heating medium The internal space of one drying chamber (27) is tangentially connected to the upper part of the machine and connected to a cyclone (31) in between via a steam conduit (30) emerging from the lower part of the drying chamber (27). The above-mentioned device is characterized in that it is connected to a rectification column (21). (7) A steam conduit (30) is connected to a cyclone (31), and the steam from the top of the cyclone, excluding solids, is passed through the steam conduit (34) by a steam fan (33).
), and the conduit (34) is connected to the control valve (35, 37).
A supply conduit for the gaseous heating medium (
29).