MX2009000699A - Method for high energy density biomass-water slurry. - Google Patents

Abstract

An energy efficient process for converting biomass into a higher carbon content, high energy density slurry. Water and biomass are mixed at a temperature and under a pressure that are much lower than in prior processes, but under a non-oxidative gas, which enables a stable slurry to be obtained containing up to 60% solids by weight, 20 - 40% carbon by weight, in the slurry. The temperature is nominally about 200 °C under non-oxidative gas pressure of about 150 psi, conditions that are substantially less stringent than those required by the prior art.

Description

METHOD FOR SUSPENSION OF BIOMASS-WATER WITH DENSITY OF ELEVATED ENERGY CROSS REFERENCE TO RELATED REQUESTS This application is a continuation in part of, and claims the benefit of Patent Application Serial Number 11 / 489,299 filed July 18, 2006.

FIELD OF THE INVENTION The field of the invention is the synthesis of transport fuel from carbonaceous supply materials.

BACKGROUND OF THE INVENTION There is a need to identify new sources of chemical energy and methods for its conversion into alternative transportation fuels, driven by many concerns including environmental, health, safety, and the inevitable future shortages of petroleum-based fuel supplies. The number of vehicles fueled by internal combustion engines worldwide continues to grow, particularly in the intermediate range of countries in the process of development. The world's automotive fleet outside the United States, which uses mainly diesel fuel, is growing faster than in the United States. This situation may change as more vehicles that take advantage of fuel use, using hybrid and / or diesel engine technologies, are introduced to reduce both fuel consumption and total emissions. Since resources for the production of petroleum-based fuels are running low, dependence on oil will be a major problem unless alternative fuels without oil are developed, particularly clean-burning synthetic diesel fuels. In addition, the normal combustion of petroleum-based fuels in conventional engines can cause serious environmental pollution unless strict exhaust emission control methods are used. A clean-burning synthetic diesel fuel can help reduce emissions from diesel engines. The production of clean combustion transport fuels requires the reformulation of existing petroleum-based fuels or the discovery of new methods for energy production or fuel synthesis from unused materials. There are many sources available, derived from carbonaceous waste materials or renewable organic. The use of carbonaceous waste to produce synthetic fuels is an economically viable method since the input supply material is already considered of low value, discharged as waste, and its disposal often contaminates.

Liquid transport fuels have inherent advantages over gaseous fuels, which have higher energy densities than gaseous fuels at the same pressure and temperature. Liquid fuels can be stored at low or atmospheric pressures while to achieve liquid fuel energy densities, a gaseous fuel must be stored in a tank in a vehicle at high pressures which can be a safety concern in the event of spills or sudden rupture. The distribution of liquid fuels is much easier than gaseous fuels, using simple pumps and pipes. The liquid fuel feed infrastructure of the existing transport sector ensures easy integration into the existing market of any production of clean-burning synthetic liquid transport fuels. The availability of clean-burning liquid transportation fuels is a national priority. The production of synthesis gas (which is a mixture of hydrogen and carbon monoxide) cleanly and efficiently from carbonaceous sources, which can undergo a Fischer-Tropsch-type process to produce clean and valuable synthetic gasoline and diesel fuels, will benefit the transportation and the health of society. A Fischer-Tropsch or reactor type process, which is defined herein to include respectively a Fischer-Tropsch process or reactor, is any process or reactor that uses synthesis gas to produce a liquid fuel. Similarly, a liquid fuel type Fischer-Tropsch is a fuel produced by said process or reactor. A Fischer-Tropsch procedure allows the application of current methods of post engine exhaust treatment with state-of-the-art NOx reduction, removal of toxic particles present in the diesel exhaust, and reduction of contaminants from normal combustion products, which is currently achieved by catalysts that are rapidly poisoned by any sulfur present, as is the case with ordinary petroleum-derived diesel fuel materials, which reduces the efficiency of the catalyst. Typically, Fischer-Tropsch type liquid fuels produced from synthesis gas derived from biomass, are free of sulfur, free of aroma, and in the case of synthetic diesel fuel have an ultra high cetane value. Biomass material is the most commonly processed carbonaceous waste supply material used to produce renewable fuels. Biomass supply materials can be converted to produce electricity, heat, valuable chemicals or fuels. California surpasses the nation in the use and development of several biomass utilization technologies. For example, only in Riverside County, California, it is estimated that approximately 4000 tons of waste wood is disposed of per day. According to other estimates, more than 100,000 tons of biomass per day are emptied into garbage dumps in the Riverside County collection area. This waste comprises approximately 30% of waste paper or cardboard, 40% organic waste (vegetables and food) and 30% of combinations of wood, paper, plastic and metal waste. The carbonaceous components of this waste material have chemical energy that can be used to reduce the need for other energy sources if they can be converted into a clean burning fuel. Those sources of carbonaceous waste are not the only available sources. Although many existing carbonaceous waste materials, such as paper, can be sorted, used and recycled for other materials, the waste producer does not need to pay a dumping fee if the waste is not delivered directly to a conversion facility. A dumping fee, currently $ 30- $ 35 per ton, is usually charged by the waste management agency to offset the disposal costs. As a result, not only disposal costs can be reduced by transporting the waste to waste processing plants to synthetic fuel, but additional disposal can be made available due to the reduced cost of disposal. The burning of wood in a wood oven is a simple example of the use of biomass to produce thermal energy. Unfortunately, open burning of biomass waste for energy and heat is not a clean and efficient method to use the calorific value. At present, many new ways of using carbonaceous waste have been discovered. For example, one way is to produce liquid transportation fuels synthetic, and another way is to produce energy gas for conversion into electricity. The use of fuels from renewable biomass sources can actually decrease the net accumulation of greenhouse gases, such as carbon dioxide, although it provides clean and efficient energy for transportation. One of the main benefits of the co-production of synthetic liquid fuels from biomass sources is that it can provide storable transport fuel while reducing the effects of greenhouse gases that contribute to global warming. In the future, these co-production procedures can provide clean combustion fuels for renewable fuel economy that can be sustained continuously. There are a number of procedures to convert hard coal and other carbonaceous materials into clean combustion transport fuels, but tend to be too expensive to compete in the market with petroleum-based fuels or produce volatile fuels, such as methanol and ethanol that have too high vapor pressure values to be used in areas of high pollution, such as the basin. Southern California air, without legislative exemption of clean air regulations. An example of the latter procedure is the Hynol Methanol process, which uses hydro-gasification and steam reforming reactors to synthesize methanol using a co-feed of materials carbonaceous solids and natural gas, and that it has a demonstrated carbon conversion efficiency of > 85% in demonstrations at laboratory scale. Of particular interest for the present invention are the most recently developed methods wherein a suspension of carbonaceous material is fed into a hydro-gasifier reactor. Said process was developed in laboratories to produce synthesis gas wherein a suspension of particles of carbonaceous material in water, and hydrogen from an internal source, are fed into a hydro-gasification reactor under conditions to generate rich air gas. This is fed together with steam in a pyrolytic steam reformer under conditions that generate synthesis gas. This procedure is described in detail in Norbeck et al., Patent application of E.U.A. No. 10 / 503,435 (published as US 2005/0256212), entitled: "Production Of Synthetic Transportation Fuels From Carbonaceous Material Using Self-Sustained Hydro Gasification." In a further version of the process, when using a steam hydro-gasification reactor (SHR) the carbonaceous material is heated simultaneously in the presence of hydrogen and steam to undergo steam pyrolysis and hydro-gasification in a single step. This procedure is described in detail in Norbeck et al., Patent application of E.U.A. Not of series 10/911, 348 (published as US 2005/0032920) entitled: "Steam Pyrolysis As A Process to Enhance The Hydro-Gasification Carbonaceous Material." The descriptions of the patent application of E.U.A. Nos. 10 / 503,435 and 10/911, 348 are incorporated herein by reference.

All these processes require the formation of a suspension of biomass that can be fed to the hydro-gasification reactor. To improve the efficiency of the chemical conversion carried out in these processes, it is desired to have a lower water to carbon ratio, therefore a suspension with high energy density which also makes the suspension more pumpable. High-solids coal / water suspensions have been successfully used in coal gasifiers in pressurized reactor feed systems. A major difference between the coal / water suspensions and the biomass / water suspensions is that the coal suspensions contain up to 70% solids by weight compared to about 20% solids by weight in the biomass suspensions. Comparing the carbon content, coal suspensions contain up to about 50% carbon by weight compared to about 8-10% carbon by weight in biomass suspensions. The polymer structure if the walls of the biomass cell consist mainly of cellulose, hemicellulose and lignin. All these components contain hydroxyl groups. These hydroxyl groups play an important role in the interaction between water and biomass, where the water molecules are absorbed to form a hydrogen bond. This high hygroscopicity of biomass is generally why the biomass suspensions are not easily produced with a high carbon content.

A number of processes have been developed to produce suspensions with high carbon content for use as a supply material for a hydro-gasifier. The JGC Corporation in Japan developed the biomass suspension fuel process, which however must be carried out under semi-critical conditions, with a temperature of 310 ° C and a pressure of 154.66 kg / cm2. The process converts the biomass with high water content into an aqueous suspension having a solids content of about 70%, which is the same level as the coal / water suspension. However, it must be carried out under high energy conditions. The Texaco researchers developed a hydrothermal pre-treatment procedure for municipal wastewater sediments involving the heating of the suspension at 350 ° C followed by an instantaneous two-stage evaporation, again requiring high energy conditions. Traditionally, wood heat treatment is a well-known technology in the firewood industry to improve the structural property of wood, but not to prepare a suspension. This decreases the hygroscopicity and increases the durability of firewood for construction. The polymer chains are segmented in heat treatment, and accessible hydroxyl groups are reduced leading to a limited interaction with water compared to untreated wood.

The aqueous liquefaction of biomass samples has been carried out in an autoclave on the scale of reaction temperature from approximately 277-377 ° C to approximately 50.96 - 203.87 kg / cm2, to obtain heavy oils rather than suspensions, which is exemplified by liquefaction of fir wood dust at approximately 377 ° C to obtain a 49% liquid yield of heavy oil. See A. Demirbas, "Thermochemical Conversion of Biomass to Liquid Products in the Aqueous Medium," Energy Sources, 27: 1235-1243,2005. There is a need for a method to concentrate the biomass to produce a suspension that does not require severe energy draining conditions from the above procedures.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an energy efficient process for converting biomass to a suspension with high energy density with high carbon content. In particular, water and biomass are mixed at a temperature and under a pressure that is much lower than those used in the above procedures, but under nitrogen, which allows a stable suspension containing up to 60% solids to be obtained in weight, to provide 20-40% percent carbon by weight in the suspension. Although the scales will be given in the detailed description, the temperature is nominally about 200 ° C under pressure of non-oxidative gas of approximately 10.54 kg / cm 2, conditions that are substantially less severe than those required by the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein; Figure 1 is a photograph of 50% by weight of a mixture of water biomass before treatment with the invention; and Figure 2 is a photograph of the water biomass mixture of Figure 1 after the treatment with the invention.

DETAILED DESCRIPTION OF THE INVENTION The term "biomass" as used herein refers broadly to material that is, or is derived from, agricultural products, wood and other plant materials, and / or vegetation, and their waste. The biomass is mixed with water in a desired weight percentage, generally 30 to 70% by weight although at a temperature in the range of 170 to 250 ° C, more preferably around 200 ° C, under non-oxidative gas pressure from 7.03 to 28.12 kg / cm2, more preferably around 10.54 kg / cm2. In the The mixture can be placed in an autoclave at room temperature and increased to the reaction temperature, or the container can be pre-heated to the desired temperature before being pressurized. The reaction temperature can range from 10 minutes to one hour or more. Although any non-oxidative gas, such as argon, helium, nitrogen, hydrogen, carbon dioxide, or gaseous hydrocarbons, or mixtures thereof, can be used, nitrogen is preferred because of its economic availability. Another preferred non-oxidative gas is hydrogen if it is available internally from the processes, and which can be particularly useful if it is carried with the suspension in a hydro-gasification reactor. Although it is desired to remove the oxidative gas, one can use a commercial grade, or less pure, of the non-oxidative gas as long as no substantial oxidation is carried out. The following examples will illustrate the invention.

EXAMPLE 1 Referring to Figure 1, a mixture of 50% biomass, consisting of pine tree particles in water before treatment is shown. Dry pine sawdust was obtained from American wood fibers and dry white cedar from Utah. This sawdust was crushed using a commercially available coffee grinder and sieved in a < 100 (150 μ ??). For the pre-treatment of wood, a system of autoclave. This consisted of a pressure vessel Autoclave Engineers EZE-Seal rated at 231.99 kg / cm2 454.4 ° C. The wood sample and deionized water were weighed and then thoroughly mixed by hand for a uniform water distribution in a large beaker before placing it in the container. The amount of wood added was adjusted for moisture content. The container was then weighed with contents, it was subjected to vacuum and purged three times with argon, and finally pressurized to 7.03 ± 0.070 kg / cm2. The temperature was raised to the operating temperature (210-230 ° C) in about 30 minutes and subsequently maintained for 30 minutes. The pressure and internal temperature were recorded using data acquisition software. After holding for 30 minutes, the heat application was stopped and the container removed from the heater. The vessel was allowed to cool to room temperature to allow head space gas collection and sample. The temperature and pressure were recorded before harvesting and then the container was weighed. The result is shown in Figure 2, which is a photograph of the suspension of Figure 1 after the treatment, which is a pumpable suspension containing 50% solids in water. The headspace gas analysis showed negligible carbon, which indicates negligible carbon loss from the suspension.

EXAMPLE 2 The procedure of example 1 was followed but the container was heated before > 200 ° C before being placed in the heater. The autoclave reached 230 ° C in 15 minutes or less and was subsequently maintained for 30 minutes. The time needed to reach the target temperature did not have a noticeable physical impact on the resulting product.

EXAMPLE 3 The method of Example 1 can be carried out but in which the starting mixture is a non pumpable agricultural waste containing 60 weight percent solids. The result will be a pumpable suspension containing 60% by weight of solids in water.

EXAMPLE 4 The method of example 1 can be carried out but in which the starting mixture is vegetation containing 40 weight percent solids. The result will be a pumpable suspension containing 40% by weight of solids in water. The suspension of a carbonaceous material resulting from the process of this invention can be fed into a hydrocarbon reactor.

Gasifier under conditions that generate rich air gas. This can be fed together with steam in a pyrolytic vapor reformer under conditions that generate synthesis gas, as described in Norbeck et al., U.S. Patent Application. Serial No. 10 / 503,435, which was mentioned above. Alternatively, the resulting suspension can be heated simultaneously in the presence of hydrogen and steam to undergo steam pyrolysis and hydro-gasification in a single step, as described in detail in Norbeck et al., U.S. Patent Application. Serial No. 10/911, 348, which was mentioned above. Although the present invention and its advantages have been described in detail, it is to be understood that various changes, substitutions and alterations may be made to the present without departing from the spirit and scope of the invention as defined by the appended claims. In addition, the scope of the application herein is not intended to be limited to the particular procedures and apparatus described in the specification. As one skilled in the art will readily appreciate from the description of the present invention, the methods and apparatuses, existing in the present or later to be developed that perform substantially the same function or that achieve substantially the same result as the corresponding embodiments described. in the present, they may be used in accordance with the present invention. Also, the appended claims are intended to include said procedures and to use said devices within their scope.

Claims (13)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for converting the biomass into a suspension with high energy density with high carbon content, which comprises providing a mixture of biomass and water containing up to 60% solids, and heating the mixture under a non-oxidative gas per What is obtained is a stable suspension containing 20-40% carbon by weight of the suspension.

2. - The method according to claim 1, further characterized in that the mixture is heated to a temperature in the range of 170 to 250 ° C.

3. The process according to claim 1, further characterized in that the mixture is heated under non-oxidative gas at a pressure of 7.03 to 28.12 kg / cm2.

4. The process according to claim 1, further characterized in that the mixture is heated to a temperature of about 200 ° C under a non-oxidative gas pressure of about 10.54 kg / cm2.

5. - The method according to claim 1, further characterized in that the non-oxidative gas is selected from the group that consists of argon, helium, nitrogen, hydrogen, carbon dioxide, or gaseous hydrocarbons or mixtures thereof.

6. A process for converting the biomass into a suspension with high energy density with high carbon content, which comprises providing a mixture of biomass and water containing 50% solids, and heating the mixture to a temperature of about 200 °. C under non-oxidative gas pressure of approximately 10.54 kg / cm2, so that a stable suspension is obtained.

7. A process in which a suspension of biomass is fed in a hydro-gasification reactor, the step of converting the biomass into a suspension with high energy density, with high carbon content, which comprises providing a mixture of biomass and water containing up to 60% solids, and heating the mixture under non-oxidative gas so that a stable suspension is obtained.

8. - The method according to claim 7, further characterized in that the mixture is heated to a temperature in the range of 170 to 250 ° C.

9. The process according to claim 7, further characterized in that the mixture is heated under non-oxidative gas at a pressure of 7.03 to 28.12 kg / cm2.

10. - The method according to claim 7, further characterized in that the mixture is heated to a temperature of around 200 ° C under a non-oxidative gas pressure of about 10.54 kg / cm2.

11. The process according to claim 7, further characterized in that the non-oxidative gas is selected from the group consisting of argon, helium, nitrogen, hydrogen, carbon dioxide, or gaseous hydrocarbons or mixtures thereof.

12. - A process in which a suspension of biomass is fed into a hydro-gasification reactor, the step of converting the biomass into a suspension with high energy density, with high carbon content, comprises providing a mixture of biomass and water containing 50% solids, and heating the mixture to a temperature of about 200 ° C under a non-oxidative gas pressure of about 10.54 kg / cm2 so that a stable suspension is obtained.

13. - The method according to claim 12, further characterized in that the non-oxidative gas is selected from the group consisting of argon, helium, nitrogen, hydrogen, carbon dioxide, or gaseous hydrocarbons or mixtures thereof.