Description

The present invention relates to a method for treating an organic starting material at high pressure and temperature in an aqueous environment to obtain one or more product streams.

A method of this kind is known per se from US patent application No. 2014/0083331. In that publication, a process stream that comprises animal waste is converted into bio-oil. Thermochemical liquefaction and catalyzed chemical modification are mentioned as a suitable method for this. The resulting bio-oil can then be processed to produce a variety of industrially useful components, including but not limited to biochar, a light liquid component, a heavy liquid component, and a bioadhesive residue. In certain situations, the processing of bio-oil comprises adding a solvent, such as acetone or an acetone/toluene mixture, to the product of thermochemical liquefaction, a mixture of biochar and bio-oil and transferring the latter to a filtration unit that separates the insoluble biochar. The bio-oil in solution is transferred to a vacuum distillation apparatus. The process conditions of the thermochemical liquefaction are stated in the examples in this document. Thus, biooil is obtained from animal waste by thermochemical liquefaction (thermochemical conversion, TCC), wherein heat and pressure are used in the absence of oxygen to break up long-chain organic substances into short-chain molecules, which give a biooil. Thus, hog manure is converted into bio-oil by TCC under conditions of a temperature of 305°C at a pressure of 10.3 MPa (103 bar) for a period of 80 minutes. Cattle, dairy or poultry manure is converted into bio-oil by thermochemical liquefaction, for example at a temperature of 350°C, with a residence time of 15 minutes, with CO as process gas, at a pressure of 2.06 MPa (20.6 bar), with the addition of sodium carbonate. It also follows from this US patent application that in the course of 2.5 h the washed reactor is heated to a temperature of 340°C and the pressure of the autoclave is increased to a reaction pressure of about 10.3 MPa (103 bar). The temperature of the reactor contents can be set alternately between about 280°C and about 360°C. With application of a temperature of 340°C and a pressure of 10.3 MPa (103 bar), the reaction is completed in about 15-20 minutes. The reactor is then cooled to room temperature by means of an ice water cooling coil and after cooling, the byproduct gas is discharged from the autoclave and the pressure in the autoclave is lowered to atmospheric pressure. Beef, dairy, hog, poultry, and sheep manure or combinations thereof are mentioned as animal waste. The viscosity of the bioresidue is below 5.0 cP (0.005 Pa.s) at 135°C. The bioadhesive composition comprises a heavy liquid fraction with a viscosity between about 0.1 cP (0.0001 Pa.s) and 0.5 cP (0.0005 Pa.s) at 135°C.

The International publication WO2014187910 relates to a method for the conversion of organic material into hydrocarbon products by a catalytic hydrothermal method, comprising decomposing the organic material into a liquid, carbon and gas, said method comprising the following steps: supplying organic material and catalysts to a hydrothermal decomposition reactor, decomposing the organic material in the hydrothermal decomposition reactor at a temperature from about 200°C to about 380°C, a pressure between 10 and 25 MPa (100-250 bar) and a residence time from about 1 to 60 minutes. The group of metal oxides and metal hydroxides in the first and second groups of the periodic table and a group of aluminosilicate compounds are mentioned as examples of catalysts.

Asphalt is a material that is made up of mineral aggregate and bitumen. Asphalt is mainly used in road construction and hydraulic engineering as pavement material.

A development in the area of asphalt is so-called bio-asphalt. Wageningen Food & Biobased Research is undertaking research to replace bitumen in Dutch asphalt on a large scale with the natural binder lignin. One of the advantages of lignin in place of bitumen in asphalt is that CO2 emission is decreased considerably thereby and the greenhouse gas is retained for a long time.

Furthermore, there is talk of a manure surplus as well as processing problems for sewage sludge and stagnating sales for processing of verge clippings and organic waste, while in addition the global demand for bitumen is increasing considerably. At the same time there is a decline in both the availability and the quality of fossil bitumen, because oil refineries are producing it less and less. In cracking plants, more-valuable substances than bitumen are obtained from crude oil.

One aim of the present invention is to provide a method for treating an organic starting material at high pressure and temperature in an aqueous environment, wherein one or more product streams are obtained that can be used as raw material for asphalt. Another aim of the present invention is to provide a method for treating an organic starting material at high pressure and temperature in an aqueous environment, wherein the process conditions are adjusted in such a way that one or more product streams with the desired properties are obtained.

Another aim of the present invention is to provide a method for treating an organic starting material at high pressure and temperature in an aqueous environment, wherein the method is carried out in such a way that a wide range of organic (residual) materials can be usefully reused.

The present invention thus relates to a method for treating an organic starting material at high pressure and temperature in an aqueous environment to obtain one or more product streams, wherein the method comprises the following steps: i) providing an organic starting material, ii) supplying the organic starting material according to i) to a reactor, iii) heating the reactor contents to a temperature T1 , iv) setting the pressure of the reactor to an absolute value P1 , v) maintaining the reactor contents at temperature T1 and pressure P1 , and vi) withdrawing one or more product streams from the reactor, wherein T1 is at least 220°C and at most 330°C, P1 is at least 50 and at most 240 bar, and step v) is carried out for a period of at least 5 minutes and at most 120 minutes.

With application of a method of this kind, one or more aims are satisfied. The present inventors found that by using specific process conditions, wherein wet organic residual streams, or mixtures thereof, are submitted to a process wherein starting materials are cracked to shorter chains, a valuable product can be produced, in particular a hard bitumen which is equivalent in properties to the harder fossil bitumen, characterized by a penetration value, softening point and which for example is used in the asphalt and roof covering industry as a binder.

In an embodiment of the present method, temperature T1 has a value of at least 240°C and a value of at most 310°C. The present inventors have established that when in step iii) a temperature range is applied that is outside the desired range, namely a temperature range of at least 220°C and at most 330°C, an end product is obtained that does not meet the intended properties. If for example a temperature lower than 220°C is employed for step iii), a bitumen is obtained as the product stream that is considered to be too soft, i.e. has a softening point that is too low and needle penetration that is too high. If for example a temperature higher than 330°C is used for step iii), a bitumen is obtained as the product stream that is considered to be too hard, i.e. has a softening point that is too high and penetration value that is too low. The needle penetration is measured according to EN 1426. The softening point is measured according to EN 1427.

In an embodiment of the present method the value of P1 is at least 100 bar, preferably at least 150 bar and at most 210 bar. If for example a pressure lower than 50 is used for step iv), a bitumen is obtained as the product stream that is considered to be too soft, i.e. has a softening point that is too low and needle penetration that is too high. The needle penetration is measured according to EN 1426. The softening point is measured according to EN 1427. If for example a pressure higher than 240 bar is used for step iv), a bitumen is obtained as the product stream that is considered to be too hard, i.e. it has a softening point that is too high and a penetration value that is too low.

In an embodiment of the present method the heating according to step iii) is carried out in such a way that the average rate at which the temperature of the reactor contents rises to temperature T1 is at least 50°C/h and at most 400°C/h, preferably so that the heating according to step iii) is carried out in such a way that the average rate at which the temperature of the reactor contents rises to temperature T1 is at least 100°C/h, preferably at least 140°C/h and at most 300°C/h, in particular at most 200°C/h. The present inventors found that when the heating stage is carried out at a rate lower than 50°C per hour and the temperature of the reactor contents finally does not exceed 220°C, a bitumen is obtained as the product stream that is too soft, i.e. has a softening point that is too low and a needle penetration that is too high.

If the temperature of the reactor contents reaches a value above 330°C or if the heating stage is carried out at a rate greater than 400°C/h and the temperature difference between the reactor contents and the temperature of the reactor wall is greater than 200°C, the bitumen yield is too low and the resultant bitumen qualifies as too hard, i.e. it has a softening point that is too high and a penetration value that is too low. The needle penetration is measured according to EN 1426. The softening point is measured according to EN 1427. In the case of a heating rate that is too high, i.e. greater than 400°C per hour, and/or a final temperature that is too high, i.e. higher than 330°C, contamination also occurs through carbonization on the inside of the reactor, so that the process does not take place under the correct conditions.

In an embodiment of the present method, the one or more product streams from vi) are submitted to a supplementary step vii), said step vii) comprising separating one or more product streams from vi) into one or more substreams. Settling, decanting, centrifugation and/or filtration may be mentioned as possible separation techniques. In general, an aqueous slurry with carbon particles is obtained as a product stream after carrying out the present method. A gas stream is also obtained as a product stream.

In an embodiment of the present method, a carbon-containing product stream according to step vi) is obtained from the slurry, and water is optionally removed from this carbon-containing product stream in a supplementary step vii). After removal of a certain amount of water, a carbon-rich substream is thus obtained. Removal of water may for example take place by drying, such as by supplying a forced cold or hot air stream. Other methods that are usual for a person skilled in this area may also be used.

In an embodiment of the present method, the water content of the carbon-rich substream formed after step vii) is at most 20 wt%, preferably at most 10 wt%, based on the total weight of the carbon-rich substream that is obtained after the optional removal of water.

In an embodiment of the present method, the carbon-rich substream is submitted to a treatment for recovery of a bitumen-containing stream from the carbon-rich substream. Extraction may be mentioned as a suitable method for recovering the intended product, namely bitumen, from the previously dewatered stream. An embodiment of extraction comprises the use of a mixture of acetone and toluene as extracting fluid, for example in a ratio of 30-70 wt% acetone and 70- 30 wt% toluene. Other extracting fluids that are usual for a person skilled in the art may also be used.

In an embodiment of the present method, the bitumen-containing stream complies with at least one property, selected from the group of a softening point between 30 and 57.5°C and a needle penetration from 20 to 100 x 0.1 mm, or a combination of both properties, the needle penetration being measured according to EN 1426 and the softening point according to EN 1427.

In an embodiment of the present method, in step i) an organic starting material is used that has a dry matter content of at least 15 wt% and at most 30 wt%, preferably at least 20 wt% and at most 25 wt%, based on the total weight of the organic starting material. If the moisture content of the organic starting material is too low, it is desirable for the dry matter content to be adjusted before the start of the present process so that it is between 15 wt% and 30 wt%. The present inventors have established that when the moisture content is too low, there is insufficient heat transfer in the reactor. In an embodiment in which the organic starting material has a dry matter content that is too high, i.e. above 30 wt%, the bitumen yield will be reduced. Furthermore, the present inventors found that the softening point of the bitumen is too high, i.e. higher than 55 to 60°C. If the moisture content of the organic starting material is too high, the softening point of the bitumen finally obtained will be too low, namely below a value of 30°C.

In an embodiment of the present method the organic starting material, as used in step i), is selected from the group consisting of grass, mushroom compost, paper and cellulose-containing residual streams, sewage sludge - whether or not digested, animal manure, vegetable, fruit and garden waste, compost obtained from vegetable, fruit and garden waste, digestate of cattle, hog and chicken manure, or one or more combinations thereof.

In an embodiment of the present method, the ash content (mineral content), determined at 815°C, in the dry matter of the organic starting material is at most 70 wt%, preferably at most 50 wt% and in particular is at most 30 wt%.

The present invention also relates to bitumen, obtained by the present method as described above. The present bitumen complies with at least one property, selected from the group of a softening point between 30 and 57.5°C and a needle penetration from 20 to 100 x 0.1 mm, or a combination of both properties, the needle penetration being measured according to EN 1426 and the softening point according to EN 1427.

In an embodiment the present bitumen has a viscoelastic characteristic G* as a function of the temperature, wherein the value for G* varies between 1x10 ⁴ - 1x10 ⁸ Pa at 20°C and between 1 and 1x10 ⁴ Pa at 80°C. The present invention is explained in more detail hereunder based on a number of examples; in no case are said examples to be regarded as limiting the extent of protection.

Fig. 1 shows a graphic representation of the softening point as a function of the needle penetration, for the parameter dry matter.

Fig. 2 shows a graphic representation of the softening point as a function of the needle penetration, for the parameter temperature.

Fig. 3 shows a schematic arrangement of a batch reactor.

Fig. 4 shows a schematic arrangement of a continuous reactor.

It can clearly be seen in Fig. 1 what values are to be preferred for dry matter when a specific range for softening point (horizontal axis) and needle penetration (vertical axis) is selected for carrying out the process in order to produce a desired bitumen. The numbers in the graph relate to the commercial quality of the bitumen. Thus, 70-100, for example, signifies that the needle penetration of this commercial bitumen is between 70 and 100 x 0.1 mm. It is thus clear that the present bitumen, namely the bitumen obtained by the present method, falls within this range. The present bitumens are thus comparable with commercial grades 70/100, 50/70, 30/45 and 20/30, but not with 160/220.

It can clearly be seen in Fig. 2 what values are to be preferred for the temperature of the reactor contents when a specific range is selected for softening point (horizontal axis) and needle penetration (vertical axis) for carrying out the process in order to produce a desired bitumen.

During the batch process 10, as shown in Fig. 3, the contents 2 of reactor 3 are held at a stable temperature (T1) for a certain length of time. This temperature (T1) is in a range from 220 to 330°C. The temperature is regulated in such a way that the absolute pressure (P1) is between 50 and 240 bar. The reactor is heated, for example electrically, with thermal oil, with steam or another source, for example with an outer jacket 2. On completion of the batch process, the contents 2 of reactor 3, namely a slurry, consisting of carbon (with the bitumen therein) and water, are discharged from reactor 3. The gas that is formed during the process can now be discharged.

Fig. 4 shows a continuous process 20, in which a continuously fed tube reactor 28 is shown. Reactor 28 is fed with raw material 21 and is heated by means of a number of heat exchangers 22, 23 and 24. Several heat exchangers may be used: for example, heat exchanger 22 may make use of a low-temperature medium, for example such as residual heat from the process, heat exchanger 23 may make use of the recovered heat from the slurry 28 from reactor 28 and heat exchanger 24 may supply extra heat by means of thermal oil, steam, electricity or another medium. The raw material stream 25 thus preheated is led into reactor 28b and is withdrawn therefrom as slurry 29.

For a continuous process (see Fig. 4), it is desirable for the process conditions such as temperature (T1), temperature differences between T1 and T2, diameter D1 and pressure P1 to be in the same range as for the batch process as shown in Fig. 3. Length L1 and diameter D1 should be selected in such a way that during the residence time, the contents 26 of reactor 28 can be kept at a stable temperature (T1), for example by means of an external jacket 27.

Examples

An amount of organic starting material was transferred to a batch reactor, as shown schematically in Fig. 1 , and then the batch reactor was heated at a certain heating rate to the desired final temperature. After setting the pressure, the reactor was maintained at that temperature and pressure for a certain length of time. On completion of the batch process, the aqueous slurry, consisting of carbon (with the bitumen therein) and water, was withdrawn from the reactor. The gas that formed during the process was discharged. The product stream obtained from the reactor was extracted by means of an extracting fluid consisting of a 50-50 mixture of acetone and toluene. Needle penetration (according to EN 1426) and softening point (according to EN 1427) of the extracted product, the bitumen, were measured.

The results of these experiments X1-X7 are presented in the following table. In the table, the organic starting materials given in the second column have the following meaning: V = hog manure, VV = old hog manure, S = sewage sludge and K = poultry manure. Table

It can be seen from the table that the bitumens obtained with hog manure (tests X1 , X2, X4 and X5) meet the desired values both for softening point (according to EN 1427) and for needle penetration (according to EN 1426). For the bitumens obtained from old hog manure, the value for the softening point (according to EN 1427) is acceptable and the value for needle penetration (according to EN 1426) is high. For the bitumens obtained from poultry manure, the value for the softening point (according to EN 1427) is high and the value for needle penetration (according to EN 1426) is acceptable. For the bitumens obtained from sewage sludge, the value for the softening point (according to EN 1427) is acceptable and the value for needle penetration (according to EN 1426) is high.