CA2816195A1 - Hydrothermal decomposition method and apparatus for making pyrolysis liquid in the range of diesel fuel - Google Patents

Abstract

Conversion of organic matter to higher value hydrocarbon products comprises the step of decomposing the organic matter into liquid, char and gas in a fast catalytic hydrothermal method that has improved efficiency due to a high local energy transfer through a cavitational effect. Organic matter and catalysts are feed to a hydrothermal decomposition reactor to decompose the organic matter into gas, vapours and char that utilizes the high local energy transfer through a cavitational effect. The reactor operates at temperatures from about 200°C to 380°C with a residence time of about 1 to 60 minutes. The product is separated into a heavy slurry of char and oil, vapours and gas where the vapours are then condensed and separated into an aqueous fraction and an hydrocarbon fraction. Part of the char slurry is recycled to a cavitation chamber and excess char is outputted from the decomposition chamber.

Description

HYDROTHERMAL DECOMPOSITION METHOD AND APPARATUS FOR MAKING
PYROLYSIS LIQUID IN THE RANGE OF DIESEL FUEL
Field of the invention The present invention relates generally to a hydrothermal decomposition method and apparatus for producing organic liquid in the range of diesel fuel from biomass or other organic matter. More particularly the invention relates to a catalytic assisted fast hydrothermal decomposition method comprising a system for the preparation of the feed and an innovative method for transferring the energy to the reaction mixture.
Background of the invention Hydrothermal decomposition treatments can be used for conversion of biomass to liquid products. In hydrothermal decomposition, also called hydrothermal liquefaction or hydrous pyrolysis, a mixture of the biomass or organic matter with some amount of water is heated in the range of 280-370 'C
under a pressure comprised between 10 and 25 MPa [9]. At these subcritical conditions the dramatic changes in the physical and chemical properties of water let it to act other than as solvent also as reactant and catalyst, and thus the feed can be directly converted into crude oil [10] that self-separates from excess water when conditions are returned to ambient temperature and pressure (Peterson et al. 2008).
Hydrothermal decomposition is well suited for processing high-and medium moisture (> 20% moisture) biomass or other organic matter, since water is used as the reaction medium and thus the organic feed can be directly processed avoiding the preliminary energy consuming drying step, necessary in the

-2-case of conventional or fast pyrolysis [10].
Owing to the ability of water in subcritical conditions to carry out condensation, cleavage, and hydrolysis reactions on organic matter, significant improvements in liquid product quality were observed in comparison with pyrolysis oil, with increased carbon content, decreased oxygen content, and reduced viscosity. Furthermore, catalysts has shown to have a positive effect on the hydrothermal decomposition processes and can increase the yield of the liquid product, as well as improve its quality.
Even if generally showing better thermal stability, quality and characteristics than the pyrolysis liquid obtained from fast pyrolysis, also the crude oil obtained from hydrothermal decomposition needs to be refined and upgraded to produce an equivalent to diesel fuel for engines.
Prior art Hydrothermal decomposition is generally known in the art, the research within the field has been rather extensive [A, B] and currently there is a growing interest in the hydrothermal treatments of biomasses to obtain commercially valuable liquid fuels. Notwithstanding this interest, all the hydrothermal technologies developed from the late '70 to the present had limited or no success, generally achieving the production of thick, highly oxygenated and thermally unstable liquid products that needed expensive refining and upgrading treatments to obtain a product in the range of diesel fuel.
This, together with the problems inherent to operate at severe conditions, the difficulties connected with the realization of a continuous process, the low liquid yield, due to the limited

-3-dry matter content in the feed and to the low conversion rates, has hampered the commercialization of these technologies and the development of economically viable processes and commercial size plants. The numerous development projects that have been terminated without commercialization underline the difficulties.
For example, one of the first research on liquefaction was performed at the Pittsburgh Energy Research Center (PERC) in the 1970s, which led in 1977 to a pilot plant in Albany, Oregon. Several technical problems and the low quality of the produced liquid, prevented the pilot unit from operating after 1981 [C, D].
Further, in 1982 Shell started a research aimed to the development of the HTU (Hydrothermal Upgrading) process, but in the late eighties this research was halted and resumed in 1997 by a Dutch consortium led by Shell with support from the Dutch Government. The started R&D program on the HTU process was targeted on the design and realization of a pilot plant, built in 2004, for obtaining data for the design of commercial plant. In the HTU pilot plant different biomasses with variable moisture content were liquefied in a range of temperatures and pressures of 300-350 C and 12-18 MPa, respectively, and a residence time of 5-20 min [E, F]. A
technical and economic feasibility study was carried out for a commercial demonstration plant capable of converting 25,000 tons of the wet organic fraction of domestic waste (dry basis)/year, that in our knowledge has not yet been built.

-4-In the eighties, EPA's Water Engineering Research Laboratory, Cincinnati, Ohio, USA, developed a prototype sludge-to-oil reactor system (STORS) capable of processing undigested municipal sewage sludge with 20% solids at a rate of 30 L/h [G].
STORS process was demonstrated in the nineties in Japan in a continuous plant capable of treating 5 tons of dewatered sludge per day, working at a temperature of 300 'C and a pressure of 10 MPa [H].
In 2001 a STORS new demonstration plant to converted raw sewage sludge to oil, located in Colton, California, and sponsored by the United States Environmental Protection Agency, was built. The technology was further developed by the ThermoEnergy Company [I].
Using its Thermal Depolymerization technology, Changing World Technologies Inc. (CWT) in 1998 started a subsidiary, Thermo-Depolymerization Process, LLC (TDP), that in 2004 led to the realization of a large-scale plant in Carthage, Missouri, USA, capable to convert 250 tons/day of turkey offal and fats into approximately 500 barrels of fuel oil of un-reported value[L, M].
Hochschule fur Angewandte Wissenschaften Hamburg, Germany (HAW) developed a technically different process named DoS
(Direct liquefaction of organic Substances), that led to a

-5-semicontinuous test plant of 5 kg/h (biomass)[N, 0].
Further, the Danish company SCF Technologies developed a process to convert organic waste to oil in the presence of a homogeneous (K2003) and a heterogeneous (Zirconia) catalyst, at subcritical conditions (280-350 C and 22-25 MPa). The so-named CatLiq technology has been demonstrated in a 20 L/h capacity pilot plant in Copenhagen, Denmark [P].
Summary of the invention It is an object of preferred embodiments of the present invention to provide a method and apparatus, which allow for a compact and efficient hydrothermal decomposition assembly. It is a further object of preferred embodiments of the present invention to provide a method for efficiently feed and pump solid organic matter, such as chopped biomass, in the hydrothermal decomposition reactor.
In a first aspect, the invention provides a method for producing liquid hydrocarbon oil from organic matter, comprising the step of decomposing the organic matter into liquid, char and gas in a fast catalytic hydrothermal process, the method comprising the steps of:
- Feeding the organic matter and catalysts to a hydrothermal decomposition reactor;
- decomposing the organic matter into gas, vapours and char by means of a high local energy transfer through a cavitational effect, while maintaining the bulk slurry temperature in the range of 250-350 C;

-6-- separating the product into a heavy slurry of char and oil, vapours and gas;
- condensing the vapours;
- separating the vapours into an aqueous fraction and an hydrocarbon fraction;
- recycling part of the char slurry to the cavitation chamber;
- conveying the excess char outer from the decomposition reactor.
In a second aspect, the invention provides an apparatus for conveniently producing liquid hydrocarbon oil from organic matter, comprising:
- a system for the convenient preparation of the feed;
- a decomposition reactor comprising a cavitation device where the local temperature sharply increases and organic matter decomposes;
- an inlet through which the organic matter can be fed into the cavitation device;
- a vapour condenser and separator;
- a char conveyor for conveying the char away from the reactor.
In the present context, organic matter is to be understood as any organic material, such as plants and animals or residues thereof, such as wood, agricultural and forestry process waste materials, or industrial, human and animal waste, including plastics and petrochemical-based waste feedstock.
The term liquid hydrocarbon oil is to be understood as any organic liquid derived from a hydrothermal decomposition process, such as bio-oil or tar, the components having a boiling point in the range 20-500 C. Vapour is to be understood as any vapour derived from organic matter in a

-7-hydrothermal decomposition process, such as vaporized hydrocarbon liquid or water.
The present hydrothermal decomposition method and apparatus confer several benefits. Thanks to the high local energy transfer through a cavitational effect no need from external heat is needed, eliminating the fouling problem of the heat exchange surfaces. The heat is given in a very effective way directly inside the organic material subject to decomposition.
It is not necessary to work under high pressure because the charge is fed directly in the cavitation chamber where the conditions necessary to initiate the hydrothermal decomposition are obtained locally by the cavitation. While the bulk temperature in the decomposition reactor is maintained at temperatures in the range of 240-380 C, locally in the cavitation chamber quasi-plasma conditions are reached assuring the energetic input for a fast hydrothermal decomposition. In fact, cavitation process is characterized by the formation, growth and implosive collapse of gas- or vapour-filled microbubbles in a body of liquid, where the collapse of these mecrobubbles leads to local transient temperatures and pressures over 5000 K and 1000 atm, respectively, with very high heating and cooling rates in the range of 1010 K/s. These conditions along with the presence of catalysts guarantee high liquid yields and the production of an oil containing a very limited amount of oxygen, having the characteristics of a diesel fuel.
The use of catalyst in the invention is particularly advantageous, in that it can be used in the production of a liquid hydrocarbon products that are higher in quality and more highly stable than typical thermal decomposition products. The catalyst consists essentially of or is a mixture of basic metal oxide or hydroxide and a aluminosilicate compound such as synthetic or natural zeolite. The basic metal

-8-oxide or hydroxide according to the present invention includes at least one oxide or hydroxide of at least one metal that provides a metal oxide or hydroxide having a measurable uptake of carbon dioxide upon heating.
In order to feed and pump solid organic matter to the reactor, a convenient system for the preparation of the feed is necessary. This system provides a continuous delivery of the charge to the reactor. It was found that the solid feedstock in the form of shredded materials and solid catalysts can be conveniently dispersed in a heavy oil at a ratio 1 of solid against 2 to 3 of oil.
In the preferred embodiment the obtained slurry is prepared in a horizontal blender adding hot recycled oil to the precharged feedstock and catalysts. During this step the mixture is homogenized, at a temperature of about 200 C. At this temperature the feedstock releases part of the moisture and also some light organic compounds, these products together to the air trapped in the solid bulk were conveyed to a condenser. While the gas is removed by a vacuum system, so avoiding the entrance of oxygen in the decomposition reactor, the condensed phase is injected directly in the cavitation chamber assuring part of the necessary water for the hydrothermal decomposition.
The so-prepared slurry is then extracted by a bottom screw conveyor and delivered to the cavitation chamber.
Because this part of the plant works as semi-continuous, in order to maintain continuous operation two horizontal blender are needed.
Description of the figures Details of embodiments of the invention are described by

-9-reference to the accompanying drawings:
= Figure 1 is a schematic representation of a decomposition system for the fast catalytic assisted hydrothermal decomposition of an a liquid organic feedstock employing method and apparatus of the present invention.
= Figure 2 is a drawing of one embodiments for the preparation of the slurry feed.
In the following description the corresponding elements as shown in each figure of the drawings are given the same reference number.
Referring to Figure 1, the fresh charge is fed to the reactor loop at the suction of the recirculation pump (1) and injected to the cavitation chamber (2) where the temperature sharply rise and sent to the reactor drum (3). At steady-state condition the temperature in the reaction drum is in the range 250-350 C. In the reactor drum the liquid from the cavitation chamber release gas and vapours that flow to the condenser (4) where the gas are vented and the vapours condensate. The condensed liquid reach by gravity the separator (5) where they separate in two phases: an hydrocarbon phase and an aqueous phase containing some oxygenated water soluble organics. The slurries, containing the produced char, that separate at the bottom of the reactor drum (3) is recycled to the cavitation chamber while a portion is extracted by the pump (6) and sent to a separation system (7) where the solid char is separated from the heavy liquid material.
In order to improve the hydrothermal decomposition in the case of dry feed, some water can be added at the entrance of the cavitation chamber.
Referring to figure 2, solid organic matter is charged together with the catalysts in the horizontal blender (1).

-10-Once the solid material is charged the blender is sealed and the hot oil coming from the char separation system (point 7 of figure 1) or a preheated mineral oil is added. The temperature inside the blender have to be high enough to assure that the slurry release of all the air trapped in the solid matter. The slurry is then sent by means of a pump (2) to the hydrothermal reactor. Due to the temperature inside the blender, moisture and some decomposition products can be released. These vapours reach a condenser (3) and the condensate is sent in the cavitation chamber.
Examples The experiments were carried out in a continuous 100L/h pilot plant equipped with a mechanical cavitation device and fed with a slurry of sawdust and mineral oil in 1:3 weight ratio.
A mixture of calcium oxide and zeolite X faujasite-type (NaX) was also used. The plant was run at the reaction temperatures indicated below. The total liquid yields and gas yields produced were indicated and in addition the characteristics of the liquid hydrocarbon product were also reported.
Example 1 Feedstock - pine sawdust (dry base) = Carbon Content: 50.7%
= Hydrogen Content: 6.2%
= Oxygen Content: 39.6%
= Nitrogen Content: 1.4%
= Ash Content: 2.1%
Catalysts amount = Calcium oxide: 5% respect to the sawdust = NaX zeolite: 2% respect to the sawdust Reactor Temperature 290 C

-11-Residence Time 10 min Run Time 8.0 hours Water 15 % respect to sawdust Total condensed hydrocarbon Yield: 32 %
Gas Yield: 18 %
Raw water yield (from sawdust) 25%
Char yield 25%
The true boiling distillation curve of the obtained hydrocarbon liquid is reported below:

¨300 0-= 200 I- = 150 0 __________________________________________________________________ Distillate cm 15 Example 2 Feedstock - pine sawdust (dry base) = Carbon Content: 50.7%
= Hydrogen Content: 6.2%
= Oxygen Content: 39.6%
20 = Nitrogen Content: 1.4%
= Ash Content: 2.1%

- 12 -Catalysts amount = Calcium oxide: 5% respect to the sawdust = NaX zeolite: 2% respect to the sawdust Reactor Temperature 270 C
Residence Time 10 min Run Time 8.0 hours Water 10 % respect to sawdust Total condensed hydrocarbon Yield: 26 %
Gas Yield: 15 %
Raw water yield (from sawdust) 22%
Char yield 37%
The true boiling distillation curve of the obtained hydrocarbon liquid is reported below:
500 ____________________________________________________ g 350 il1 a 250 CD
o.200 1' 150 0 ___________________________________________ Distillate (lk)

Claims (28)

1. A method for the conversion of organic matter to higher value hydrocarbon products, comprising the step of decomposing the organic matter into liquid, char and gas in a fast catalytic hydrothermal method, the method comprising the steps of:
- Feeding the organic matter and catalysts to a hydrothermal decomposition reactor;
- decomposing the organic matter into gas, vapours and char in a hydrothermal decomposition reactor, by means of a high local energy transfer through a cavitational effect, the reactor operating at a temperature from about 200 °C to about 380 °C and at a residence time of about 1 to 60 minutes;
- separating the product into a heavy slurry of char and oil, vapours and gas;
- condensing the vapours;
- separating the vapours into an aqueous fraction and an hydrocarbon fraction;
- recycling part of the char slurry to the cavitation chamber;
- conveying the excess char out of the decomposition reactor.

2. The method of claim 1, wherein organic matter in the hydrothermal decomposition reactor is subjected to a high local energy transfer through a cavitational effect.

3 The method of claim 1 and 2, wherein the hydrothermal decomposition is favoured by addition of water at the entrance of the cavitation chamber.

4. The method of claim 1 and 2, wherein the residence time in the decomposition reactor is between 5 and 30 minutes.

5. The method of claim 2, wherein the cavitational energy is provided in a cavitation chamber.

6. The method of claim 5, wherein the cavitation energy is provided by mechanical devices or ultrasounds transducers.

7. The method of any of the preceding claims, wherein the decomposition vapors diffuse into a condenser, in which said step of condensation takes place.

8. The method of any of the preceding claims, wherein at least a portion of said char is in the form of fine particles, which, at the step of conveying, are conveyed away from the reactor in the form of slurry.

9. The method of claim 8, wherein the slurry is conveyed in a stagnant zone, in which said particles essentially separate from heavy organic liquids.

10. The method of claim 9, wherein heavy liquids are recycled to the decomposition reactor.

11. The method of any of the preceding claims, wherein the decomposition reactor is fed by a slurry of organic matter and catalysts.

12. The method of claim 11 where the organic matter is selected from the group consisting of: plant biomass, bio-renewable fats and oils, animal biomass, organic municipal waste, sewage sludge, plastics and petrochemical-based waste feedstock.

13. The method of claim 11, wherein the solid particles are suspended in a heavy oil.

14. The method of claim 13, wherein the heavy oil is a product with a boiling point higher than 280 °C.

15. The method of claim 14 wherein the heavy oil is a mineral oil.

16. The method of claim 11 wherein the catalysts are selected respectively from the group of oxides and hydroxides of metal within the first and second group of the periodical system and from a group of aluminosilicate compounds.

17. The method of claim 16 wherein the catalysts from the group of oxides and hydroxides of metal within the first and second group of the periodical system is NaOH or KOH or Ca(OH)2 or CaO.

18. The method of claim 17 wherein the catalysts from the group of aluminosilicate compounds is a synthetic or natural zeolite.

19 A fast hydrothermal decomposition apparatus for producing high value hydrocarbon liquid, char and gas from low value organic matter, comprising:
- a system for the convenient preparation of the feed;
- a decomposition reactor comprising a cavitation device where the local temperature sharply increases and organic matter decomposes;
- an inlet through which the organic matter can be fed into the cavitation device;
- a vapour condenser and separator;
- a char conveyor for conveying the char away from the reactor.

20. The apparatus of claim 19, wherein the cavitation device is a mechanical device or a ultrasound transducer

21. The apparatus of claim 19 and 20, wherein the mechanical device is a pump.

22. The apparatus of any of claims 19-21, wherein the heat for the decomposition process is provided directly inside the reacting mixture without solid exchange surfaces.

23. An apparatus for the preparation of the slurry, comprising:
- a solid liquid mixer;
- a degassing system - a vapour condenser

24. the apparatus of claim 23, wherein the mixer is an horizontal mixer.

25. The apparatus of claim 23, wherein the solid is constituted of solid organic matter and catalysts.

26. The apparatus of claim 23 and 25, wherein the slurry is produced adding an organic heavy oil to the pre-charged solids.

27. The apparatus of claim 26, wherein the oil is a hot recycled oil.

28. The apparatus of any claims 23-26, wherein the vapours are condensed and sent at the entrance of the cavitation chamber.