Patent Application
20130118075
The present invention relates to a system for thermal conversion of carbon based materials. More specifically, the present invention relates to a system for thermal conversion of carbon based materials into combustible oil and/or gas. Further, the present invention relates to a method for thermal conversion of carbon based materials into combustible oil and/or gas. The present invention also relates to the use of the present system for thermal conversion of carbon based materials into combustible oil and/or gas.
One of the objectives of thermal conversion of carbon based, or carbon comprising matter, for example biomass, wood, forestry waste products, organic waste, agricultural waste products, plastics, tires, tar sand, industrial waste, municipal waste, airport waste, entertainment industry waste, harbour waste, hospital waste or reject coal, is the production of a combustible oil or gas, i.e. an oil or gas that can be used as a fuel source for engines, turbines, heating devices, steam devices etc.
When carbon based materials are heated under reduced oxygen pressure, such as in the absence of oxygen, in a closed vessel or chamber, the molecular structure of these carbon based materials disintegrates. As a result of this disintegration, combustible gasses such as hydrogen, methane and/or ethane are formed next to combustible oils comprising larger carbon chains.
The process of thermally disintegrating carbon based, or carbon comprising, materials under a reduced oxygen pressure is also designated as thermal cracking or pyrolysis.
Thermal cracking, or thermal disintegration or pyrolysis, of carbon comprising materials is a technique that can be used to convert these materials into valuable combustible oil and gas that subsequently can be used, for example, to power vehicles, generate electricity in turbines or as base products for chemical synthesis.
Problems associated with many thermal cracking processes are the design of a process capable of producing only one product, the liquids obtained from the thermal cracking process not having the desired properties, and the synthesis gas in many cases containing tar, giving clogging problems in various applications.
Another problem of thermal cracking, and especially gasification, is the phenomenon that minerals and especially salts, present in the input will reach their softening point at temperatures above approximate 750° C. (high potassium content, typical for rice husks) through approximate 900° C. (typical for wood and mixed waste), resulting in clogging of the gasifier equipment.
Yet another problem of the known systems for the conversion of carbon based materials is large scale of the equipment required. Providing such a large scale system requires enormous investments and substantive installation times.
Yet another problem associated with thermal cracking is cooling and cleaning of the hot synthesis gas. Due to a combination of tar and coke formation in practice, no coolers can be installed to recover heat and wet gas cleaning equipment is required. Therefore, the thermal efficiency of current thermal cracking processes is low and contaminated waste water is produced.
The current thermal cracking systems and processes are not suitable to integrate novel technologies such as oxygen membranes and fuel cells, due to the tar content and the presence of salt vapour. Therefore extra heating/cooling and gas treatment equipment is required.
In many prior art disclosures, the problem of tar in the production of synthesis gas, or any kind of fuel gas from a pyrolysis or gasification process, is addressed. Apart from thermal cracking by adding oxygen or air, also steam reforming, catalytic conversion, tar removal by fuel gas washing, and recycling the washed out tar back to a pyrolysis reactor are described as solutions.
Considering the above, there is a need in the art for a system and a method for thermal conversion of carbon based materials into combustible oil and/or gas obviating at least part, if not all, of the above problems.
Therefore, it is an object of the present invention, amongst other objects, to provide a system obviating at least part, if not all, of the above problems associated with conversion of carbon based materials into combustible oil and/or gas. This objective, amongst other objects, is met by a system as defined in the appended claim 1.
Specifically, this objective, amongst other objectives, is met by a system for the thermal conversion of carbon based materials into combustible oil and/or gas, said system comprises:
The present inventors have surprisingly discovered that a high quality oil and/or gas is obtained when thermal decomposition of carbon based materials is performed with the present system. Through using a series of separate reactors, in a specific order, the process conditions for each subprocess can be optimized. This results in an advantageous thermal efficacy and high conversion rates. Additionally, the use of several specific reactors enables the system to be built up in a flexible and cost effective way. Moreover the system may be embedded in a local (agricultural) infrastructure in order to provide a relatively small scale conversion plant.
Yet another advantage of the present system is that the gas produced, or synthesis gas, is practically tar free, thereby avoiding clogging in the various applications.
The present first fluid bed reactor for thermal cracking according to the present invention may also be designated as a reactor for thermal cracking or thermal cracker. Thermal cracking is a refining process in which heat and pressure are used to break down, rearrange, or combine carbon molecules. In the past, fuels and heavy oils were heated under pressure in large drums until they cracked into smaller molecules. However, the advantage of using a fluid bed reactor is the ease of maintaining a uniform temperature through the cracking reactor. This uniform temperature avoids the appearance of hot spots. Preferably, is the oil vapour produced by the reactor removed within 2 seconds, thereby avoiding secondary cracking reactions. Additionally, the fluid bed reactor may comprise a Lewis acid. Preferably the fluid bed reactor is heated by hot gas from said fourth moving bed reactor.
The present second vapour wash reactor may, in the present context, also be denoted as vapour washer. A vapour washer washes the (hot) effluent vapour and gas and/or may separate heavy oil fractions. Preferably the present vapour wash reactor is a packed washing column. Preferably the vapour wash reactor is cooled directly by circulating product oil.
The present third reactor may also be denoted as fractionation reactor, or fractionation column. Fractionation is a separation process in which a mixture is divided in a number of desired fractions, wherein the composition of the fraction changes according to their gradient. The present third reactor separates and fractionates the product oil or combustible oil. One example of fractionation reactor type is a packed column. The present third reactor may be cooled directly by circulating product oil.
“Carbon comprising solid material” or “solid material” within the present context is a material which is solid after processing in the present first fluid bed reactor. An example of such material is char or charred materials.
The present fourth moving bed reactor as used in the present context may also be denoted as a saturation reactor. This reactor stabilizes carbon in the solid materials, which solid materials are preferably derived from said first fluid bed reactor. The advantage of such a stabilisation processing is for example that stabilized char cannot longer contribute to the formation of tar.
Present fifth fluid bed reactor as used in the present context may also be denoted as quenching reactor or chemical quench. Preferably the fifth fluid bed reactor has a double role: gasification of the stabilised carbon comprising solid material while cooling the gas derived from, preferably, said sixth reactor. One advantage of this counterflow is thermal efficacy.
Present sixth reactor may, according to the present invention, also be denoted as gasification reactor or gasifier. Gasification is a process that converts carbon based materials into carbon monoxide and hydrogen. This resulting gas mixture is so called synthesis gas or syngas. Gasification is characterized by its high temperatures which distinguished from for example biological processes. Preferably the sixth reactor according to the present invention is a pipe reactor.
According to a preferred embodiment of the present invention, the first fluid bed reactor is connected through at least one inlet for receiving the carbon based materials with a dryer. The dryer comprises at least one inlet for receiving solid carbon based materials, at least one outlet for transporting dried solid carbon based materials into the first fluid bed reactor and at least one outlet for discharging non-carbon based material.
The present dryer is preferably a fluid bed reactor. The temperature in the dryer is preferably between 80° C. to 120° C., more preferably between 90° C. to 110° c. Preferably the oxygen pressure within the dryer is between 10 to 40 mbar. One advantage of the present dryer is that more carbon based materials can be processed. Accordingly, the applicability of the present system is increased.
According to another preferred embodiment, the first fluid bed reactor is connected through at least one inlet for receiving said carbon based materials with an homogeniser. The present homogeniser comprises at least one inlet for receiving liquid carbon based materials and at least one outlet for transporting homogenised liquid carbon based materials into the first fluid bed reactor.
The homogeniser is preferably a stirred tank reactor. The temperature in the homogeniser is preferably between 80° C. to 120° C., more preferably between 90° C. to 110° c. Preferably the oxygen pressure within the homogeniser is between 1 to 10 mbar. One advantage of the present homogeniser is that more carbon based materials can be processed or converted. For example, oil sludges or tar sand can be processed in the system according to the present invention.
According to a preferred embodiment, the fifth reactor is connected through at least one outlet for gas with a gasfilter. The present gasfilter comprises at least one inlet for receiving gas and at least one outlet for discharging combustible gas.
The present gasfilter is preferably a sediment filter, more preferably a bagfilter. The gasfilter may be used for the removal from dust from the gas. Preferably operating temperature is between 200° C. and 240° C. It is preferred that the hydrogen pressure of the gasfilter is 200 to 300 mbar, more preferably 225 to 275 and/or the oxygen pressure is 10−5 to 10−9 mbar, more preferably 10−6 to 10−8 mbar.
According to a preferred embodiment, transport of solid material between the reactors is effected by fluming. More preferably the fluming is effected by pressurised gas. Through the use of fluming, hot process streams can be readily transported between the separate reactors.
According to a preferred embodiment, the pressure in the reactors is higher than atmospheric pressure.
According to yet another preferred embodiment, the present system comprises an oxygen membrane between the third reactor and the sixth reactor for oxygenation and/or oxidation of the non-condensed gas.
The present oxygen membrane may also be denoted as an oxygen transport membrane. Usually, oxygen membranes exploit unique properties of mixed conducting ceramic materials, which transport both oxygen and electrons across a gas impermeable membrane. According to the present system, the oxygen membrane is used for the selective transfer of oxygen ions to the present sixth reactor. Preferably the oxygen membrane comprises hollow ceramic elements. The temperature in the oxygen membrane is preferably of 850° C. to 1000° C.
According to another preferred embodiment, the gas from the outlet for gas of the fifth fluid bed reactor is transported to the gasfilter through the fourth moving bed reactor and/or the first fluid bed reactor. One advantage of this preferred embodiment is the thermal efficacy which is obtained by the using the heat of the gas of the fifth fluid bed reactor.
According to yet another preferred embodiment, the present carbon based materials are selected from the group consisting of biomass, wood, forestry waste products, organic waste, agricultural waste products, plastics and tires, or any combination thereof.
Considering the advantages of the present system, the present invention, according to another aspect, relates to a method for the thermal conversion of carbon based materials.
More specifically, the present invention relates to a method for the thermal conversion of carbon based materials into combustible oil and/or gas comprising introducing carbon based materials into a system according to the present invention.
In a preferred embodiment of the method according to the invention, the residence time in the first fluid bed reactor is 30 to 90 minutes, the residence time in the second vapour wash reactor is 0.5 to 5 seconds, the residence time in the third reactor is 1 to 5 seconds, the residence time in the fourth moving bed reactor is 180 to 240 minutes, the residence time in the fifth fluid bed reactor is 30 to 120 minutes, and/or the residence time in the sixth reactor is 1 to 5 seconds.
According to yet another aspect, the present invention relates to the use of the present system for thermal conversion of carbon based materials into combustible oil and/or gas.
To the
Further, the discharge of the distillation device adapted for discharging at said least one gaseous fraction is connected with an inlet of the first gasification device.
Further, the distillation device (3) comprises third heating means for heating the product flow led in the distillation device.
Further, the first cracking device and the second cracking device are the same device (2).
Further, the system comprises an aerator connected to the inlet of the first gasification device for supplying air to the first gasification device.
Further, the discharge of the second gasification device is connected with a thermally conducting discharge pipe for discharging the first gas fraction and the second gas fraction.
Further, the thermal conducting discharge pipe extends through the first cracking device, the second cracking device and/or the aerator.
Further, the discharge of the second cracking device is connected with the inlet of the first cracking device for leading back to the first cracking device at least a part of the heavy liquid fraction originating from the second cracking device.
Further, the separation device and the second gasification device are the same device (4)
Further, the second gasification device is provided with means for causing the first gas fraction to flow through the rest fraction.
Further, the system is provided with administration means connected to a discharge of the first gasification device for the administration of the first gas fraction to the second gasification device, whereby the means of administration extend to the lower zone of the second gasification device.
Further, a discharge for at least a part of the first gas fraction and/or at least a part of the second gas fraction is arranged in a way such that the means of administration extend to the lowermost zone of the second gasification device.
Further, the system reflects a method for the thermal cracking of a mass comprising hydrocarbons. The process can be operated in three major reactors. The first part is the saturator (1) where liquid hydrocarbons with a high condensing temperature are removed from the char. The second part is the gasifier (2), an empty reactor providing a hold up time, where these liquid hydrocarbons, possible with other synthesis gas from the pyrolysis or gasification process, are gasified at a temperature of typically 1200° C. to 1400° C. The third part is the chemical quench (3), where the hot synthesis gas of the gasifier (2) is used for for the endothermic gasification of the char from the saturator (1). The process is characterized by leading hot synthesis gas from the second part of the process, the gasifier, to the third part of the process, the chemical quench (3), where the hot synthesis gas gasifies the stablised char from the saturator (1). This reaction is endothermic and therefore decreases the temperature of the synthesis gas to a temperature of typically approximate 700° C. to 800° C. depending on the choice of operation. The chemical quench (3) is a closed vessel fed with stabilised char that was treated in the saturator (1). Because the stabilized char does not release liquid hydrocarbons, the synthesis gas practically does not contain any tar. The char is reduced to ashes and discharged from the vessel of the chemical quench. In particular said system, comprises the steps of:
Further heating the mass during step B) to a temperature of between 200° C. and 700° C., preferably between 300° C. and 600° C.
Further separating of the mass during step B) in a reducing atmosphere.
Further heating the mass during step H) to a temperature of between 500° C. and 800° C., preferably between 500° C. and 600° C.
Further pyrolysing the mass during step H) in a reducing atmosphere.
Further, performing step C) in a time interval of between 1 and 10 seconds after step B) is initially performed.
Further, the heavy liquid fraction has a condensation temperature between 150° C. and 600° C.
Further, the light fraction has a condensation temperature lower than 150° C.
Further, leading the first gas fraction during step L) through at least a part of the rest fraction.
Further, fluidizing at least a part of the rest fraction during step L) by the first gas fraction flowing through the rest fraction.
Further, heating the mass during step B) to a temperature of between 500° C. and 800° C., preferably between 550° C. and 650° C.
Further, performing step D) during a time frame of between 0 to 10 seconds, preferably between 0 to 1 second.
Further, the heavy liquid fraction having a condensation temperature of between 150° C. and 600° C.
Further, heating the heavy liquid fraction during step D) to a temperature of 1100° C. and 1500° C., preferably between 1200° C. and 1400° C.
Further, performing the gasification according to step L) at a temperature of between 500° C. and 900° C., preferably between 700° C. and 800° C.
Further, the gas fraction comprises at least one substance selected from the group comprising: hydrogen, carbon monoxide, carbon dioxide, and steam.
Further, the separation device and the second gasification device are mirtually connected, and that the system comprises transportation means for the transportation of the rest fraction formed in the separation device to the second gasification device.
Further, the separation device and the second gasification device are part of the same device.
Further, the second gasification device is provided with means for causing the first gaseous fraction to flow through the rest fraction.
Further, the system comprises administration means connected with the discharge of the first gasification device for administrating the first gaseous fraction to the second gasification device, whereby the administration means extend to the lower section of the second gasification device.
Further, the discharge for the discharging of at least a part of the first gaseous fraction and at least a part of the second gaseous fraction is accommodated in the upper section of the second gasification device.
Further, the system of
Further, the second gasification device and the separation device form part of the same device.
Further, leading the first gaseous fraction during step F) through at least a part of the rest fraction.
Further, the fluidisation of at least a part of the rest fraction during step F) by the gaseous fraction.
Further, heating the mass during step B) to a temperature between 500° C. and 800° C., preferably between 550° C. and 650° C.
Further, performing step D) within a time frame of 0 to 10 seconds, preferably within 0 to 1 second.
Further, the condensation temperature of the heavy liquid, being between 150° C. and 600° C.
Further, the heating of the heavy liquid fraction during step D) to a temperature between 1100° C. and 1500° C., preferably between 1200° C. and 1400° C.
Further, performing of the gasification according to step G) at a temperature between 500° C. and 900° C., preferably between 700° C. and 800° C.
Further, the gaseous fraction comprising at least one substance selected from the group comprising carbon monoxide, carbon dioxide, and steam.
Further, at least one second discharge of the distillation device (2) is equipped for the discharge of at least one light liquid fraction and that at least one other second discharge of the distillation device (2) is equipped for the discharge of at least one gaseous fraction.
Further, the cracking device (1) comprises first heating means for the heating of the pyrolysable mass
Further, the distillation device (1) comprises heating means for the heating of the in the distillation lead product flow.
Further, the system comprises at least one closing device for closing the discharge of the cracking device from the inlet of the distillation device.
Further, the system comprises at least one second closing device for closing the discharge of the distillation device from the inlet of the cracking device.
Further, the figure reflects a method for cracking of a pyrolysable mass, particularly hydrocarbons, preferably using the device according to
A) leading of a pyrolysable mass into a cracking device (1),
B) at least partial pyrolysing of the mass by means of heating the mass in the cracking device (1) whereby a substantially gaseous product flow is formed,
C) leading of at least one part of the substantially gaseous product flow to the distillation device (2),
D) by means of distillation separating the product flow in the distillation unit (2) in at least one heavy liquid fraction and at least one light fraction,
E) removing from the distillation device (2) of at least on part of the light fraction, and
F) leading at least one part of the heavy liquid fraction from the distillation device (2) to the cracking device of.
Further, heating the pyrolysable mass to a temperature of between 200° C. and 700° C., preferably between 300° C. and 600° C.
Further, pyrolysing of the mass during step B) in a reducing atmosphere.
Further, submitting the mass during the pyrolysing to a reducing substance that is formed by at least one substance chosen from the group consisting of: hydrogen, carbon monoxide, and steam.
Further, performing step C) within a timeframe of 1-10 seconds after step B) initially is performed.
Further, a heavy liquid fraction having a condensation temperature that amounts between 150-600° C.
Further, the light fraction having a condensation temperature being less than 150° C.
Further, steps B), C), D) being repeated at least one time after step F) is performed.
Further, the thermal cracking is operated typically at 300 to 600° C. at elevated temperature. With this method the products from a thermal cracking process are, removed and then fed to a distillation process within a hold-up time of typically 1 to 10 second, preferably 2 seconds. In the distillation process the products of the thermal cracking process are separated into three fractions, a gaseous fraction, a light liquid fraction and a heavy liquid fraction. The residue is fed back to the thermal cracking process or can be tapped directly as a product if desirable. This fraction also contains dust particles, which are carried by the gas flow into the distillation process. Also these particles are returned to the thermal cracking process or are tapped. The light liquid fraction is an oil fraction that does therefore not contain dust particles and can therefore be used as an engine or boiler fuel.
Further,
A) leading of the combustible material though the gasification device,
B) converting the biomass by means of heating in the gasification device in a product gas and a rest fraction,
C) discharging at least a part of the formed product gas through the first discharge from the gasification device, and
D) removing the gasification device at least a part of the rest fraction through the second discharge from the gasification device using an eductor, at least a part of the removed product gas being led through the eductor as a propellant.
Further, the product gas comprises at least one of the following components: flue gas, methane, water vapor, nitrogen, carbon monoxide, hydrogen, and/or carbon dioxide.
Further, the pneumatic transport is realized by an educator as a system to transport coal, coal products, charred material and ashes from one reactor to another using synthesis gas or flue gas as a drive gas. With pneumatic transport bulk particles are driven through pipes by means of blowing a gas, in most cases air, through the pipes at high speed.
The drive gas is blown in to an educator placed in the middle of the pneumatic system, therefore creating a flow of drive gas in one direction. This flow of drive gas creates a lower pressure in the pipe section before the joint where the educator is placed. The lower pressure creates a flow of gas created by a pyrolysis or gasification process, carrying particles from one reactor to the other. Because drive gas is flue gas or synthesis gas, no (partial) combustion of the gas or particles take place.
The principles of the present invention will be further detailed in the following example showing a preferred embodiment of the present invention. In the example, reference is made to
The first fluid bed reactor (1) produces hot effluent vapour and gas which is transported to a second vapour wash reactor (2). The remaining carbon comprising solid materials are transported to a fourth moving bed reactor (4) and remaining metals and minerals are discharged from the system and collected.
The hot effluent vapour and gas are in the second vapour wash reactor (2) subjected to the conditions:
The second vapour wash reactor (2) produces washed vapour and gas which is transported (104) to a third reactor (3). The remaining solids and oil are transported (105) to the first fluid bed reactor (1).
The washed vapour and gas are in the third reactor (3) subjected to the conditions:
The third reactor (3) produces combustible oil and non-condensed gas. The combustible oil is discharged (106) from the system and collected. The non-condensed gas is transported (107) to an oxygen membrane (10).
The non-condensed gas is in the oxygen membrane (10) subjected to the conditions:
The oxygen membrane (10) produces oxygenated gas which is transported (108) to a sixth reactor (6) for gasification.
The oxygenated gas is in the sixth reactor (6) subjected to the conditions:
The sixth reactor (6) produces processed gas which is transported (109) to a fifth fluid bed reactor (5) for cooling processed gas and gasification of stabilized carbon comprising solid material.
The processed gas is in the fifth fluid bed reactor (5) subjected to the conditions:
The fifth fluid bed reactor (5) produces cooled gas and gasified stabilized carbon comprising solid material. The gas is transported (110) via a fourth moving bed reactor (4) and the first fluid bed reactor (1) to a gasfilter (9). The gasified stabilized carbon comprising solid material is transported (111) to the first fluid bed reactor (1).
The cooled gas is in the gasfilter (9) subjected to the conditions:
The gasfilter produces combustible gas and filter dust. The combustible gas and filter dust are discharged (112 and 113 respectively) from the system and collected.
The remaining carbon comprising solid materials are in the fourth moving bed reactor (4) subjected to the conditions:
The fourth moving bed reactor (4) produces stabilized carbon comprising solid material which is transported (114) to the fifth fluid bed reactor (5).
The dryer (7) receives solid carbon based materials. These solid carbon based materials are in dryer subjected to the conditions:
The dryer (7) produces dried solid carbon based materials which are transported (115) to the first fluid bed reactor (1) and remaining metals and minerals are discharged (116) from the system and collected.
The homogenizer (8) receives liquid or semi-liquid carbon based materials. These liquid or semi-liquid carbon based materials are in the homogenizer (8) subjected to the conditions:
The homogenizer (8) produces homogenized liquid carbon based materials which are transported (117) to the first fluid bed reactor (1).
By importing a mass of 1000 kg, containing plastics (20%), wood (40%) and organic waste (40%) in the system, the following products were obtained.
The calorific value of the synthesis gas obtained by the system according to the example was 5.1 MJ/Nm3. Moreover, the gas was free of tar.
An analysis of the combustible oil obtained by the above system is shown in table 1 below.
Forthcoming, the combustible oil obtained in the above example has a good quality, as is further elucidated by
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/NL2010/000109 | Jul 2010 | NL | national |
| PCT/NL2010/000110 | Jul 2010 | NL | national |
| PCT/NL2010/000111 | Jul 2010 | NL | national |
| PCT/NL2010/000112 | Jul 2010 | NL | national |
| PCT/NL2010/050464 | Jul 2010 | NL | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/069881 | 12/16/2010 | WO | 00 | 1/20/2013 |
