REACTOR AND METHOD FOR CONVERSION OF A CARBONACEOUS MATERIAL

Abstract

A method for the conversion of a carbonaceous material. The method comprising the steps of providing a carbonaceous material, providing a hot powder material and contacting the carbonaceous material and the powder material in an atmosphere configured to no more than partially oxidize carbon to CO.sub.2. The carbonaceous material is at least a partial converted into volatiles. The volatiles are separated from the additional components by specific gravity.

Claims

1-17. (canceled)

18. A reactor for converting a carbonaceous material, the reactor is configured to accommodate a solid powder material and having an upper portion and a lower portion; the reactor comprising: at least one solid material inlet for providing a solid carbonaceous material and a powder material to the reactor, at least one solid material outlet configured for allowing the removal of converted carbonaceous material and/or a powder material, said outlet comprising adjusting means configured to adjust the level or amount of solid material in the reactor, fluidizing means adapted to fluidize powder material, a gas outlet preferably located in the upper portion of the reactor, and gas-solid separation means configured to substantially separate a gas from a solid material, wherein the gas-solid separation means being a section of the upper portion of the reactor having a larger flow area than the lower portion of the reactor configured to separate gas and solids in a substantially vertical flow and to reduce the velocity of the gas to below an entrainment velocity of the solids, wherein the reactor being configured so that the conversion of the carbonaceous material takes place as the carbonaceous material contacts and is heated by the heated powder material.

19. The reactor for converting a carbonaceous material according to claim 18, wherein the at least one solid inlet is located in an upper portion of the reactor.

20. The reactor for converting a carbonaceous material according to claim 18, wherein the outlet has a fluid trap configuration which provides the adjusting means that adjusts the level of solid material in the reactor when the powder material is fluidized.

21. The reactor for converting a carbonaceous material according to claim 20, wherein the fluid trap configuration comprises a first conduit being fluidly connected to the lower portion of the reactor and a lower portion of a second conduit is fluidly connected to the first conduit, thereby allowing powder to flow from the reactor, through the first conduit, to an upper portion of the second conduit.

22. The reactor for converting a carbonaceous material according to claim 21, wherein the first conduit is configured to provide a protective layer of solids above a at least a portion of the lower surface of the first conduit by varying the cross-sectional dimension value through the length of the first conduit.

23. The reactor for converting a carbonaceous material according to claim 21, wherein the first conduit comprises an internal mesh.

24. The reactor for converting a carbonaceous material according to claim 18, wherein the at least one solid material inlet is configured to substantially prevent upstream process gas to flow into the reactor together with the carbonaceous material and/or a powder material.

25. The reactor for converting a carbonaceous material according to claim 21, wherein the gas outlet is fluidly connected to the second conduit.

26. A method for the conversion of a carbonaceous material comprising the steps of: providing a carbonaceous material having a conversion temperature; providing a powder material having a temperature higher than the conversion temperature of the carbonaceous material; contacting the carbonaceous material and the powder material in an atmosphere configured to no more than partially oxidize carbon to CO.sub.2, to obtain at least a partial conversion of the carbonaceous material into a converted material and a volatile product; fluidizing the carbonaceous material and the heated powder material; separating by specific gravity by directing a gas flow comprising the volatile product in an upwards direction to provide a fraction substantially comprising the volatile product and a second fraction substantially comprising additional components, said additional components being the powder material, converted material and optionally non-converted or partially converted carbonaceous material removing the second fraction through a solid material outlet to adjust the level of fluidized solid material, wherein the contacting between the carbonaceous material and the powder material takes place in at least two different flow regimes, and wherein the conversion of the carbonaceous material takes place as the carbonaceous material contacts and is heated by the heated powder material.

27. The method for the conversion of carbonaceous material according to claim 26, wherein the velocity of the gas flow in the upwards direction is decreased to below an entrainment velocity of the additional components.

28. The method for the conversion of carbonaceous material according to claim 26, wherein pulses of gas is provided to fluidize the carbonaceous material and the heated powder material.

29. The method for the conversion of carbonaceous material according to claim 26, wherein the method comprises the additional step of: providing a reactant gas or optionally a precurser for a reactant gas into the atmosphere configured to no more than partially oxidize carbon to CO.sub.2, optionally heating the precurser to develop the reactant gas and contacting the reactant gas with a mixture of the heated pulverized material and the carbonaceous material.

30. The method for the conversion of carbonaceous material according to claim 26, wherein the powder material and carbonaceous material initially are contacted and transported in an entrained flow in the atmosphere configure to no more than partially oxidize carbon to CO.sub.2 in a first direction and the gas pulses and/or reactant gas is provided in counter-flow from a second direction substantially opposite of the first direction.

31. The method for conversion of carbonaceous material according to claim 26, wherein the powder material is cement meal and preferably wherein the heating of the cement meal is carried out in a cement clinker manufacturing process, such as in the pre-heater of the cement clinker manufacturing process.

32. The method for conversion of carbonaceous material according to claim 26, wherein the carbonaceous material is selected from the group comprising alternative fuels, waste and/or biomass fuels.

33. A cement clinker manufacturing plant comprising the reactor according to any of claims 18 to 25.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0113] The invention will be described in more details below by means of non-limiting examples of presently preferred embodiments and with reference to the schematic drawings, in which:

[0114] FIG. 1 shows a schematic cross-sectional view of a reactor for converting a carbonaceous material according an embodiment of the invention;

[0115] FIG. 2 shows a schematic cross-sectional view of a reactor for converting a carbonaceous according to another embodiment of the invention, wherein the reactor comprises a material screw for regulating solid material in the reactor;

[0116] FIG. 3 shows a schematic cross-sectional view of a reactor for converting a carbonaceous material according to another embodiment of the invention wherein the reactor comprising a first and second conduit that together with the reactor forms an essential U-shape;

[0117] FIG. 4 shows a schematic cross-sectional view of a reactor for converting a carbonaceous material according to yet another embodiment of the invention, wherein the reactor comprises a gas by-pass conduit;

[0118] FIG. 5 shows a schematic cross-sectional view of a reactor for converting a carbonaceous material according to another embodiment of the invention, wherein the second conduit has an increase in flow area;

[0119] FIG. 6 shows a schematic cross-sectional view of a reactor for converting a carbonaceous material according to another embodiment of the invention wherein the reactor has an extended radius design; and

[0120] FIG. 7 shows a schematic overview of an extract of a cement manufacturing process comprising a reactor according to one embodiment of the invention.

DETAILED DESCRIPTION

[0121] FIG. 1 shows a schematic drawing of a reactor 1 for converting a carbonaceous material. The reactor 1 has a reactor chamber 2 which is configured to accommodate a solid powder material. The reactor 1 has a lower portion 10 and an upper portion 11 and comprises a solid material inlet 20 for providing solid material to the upper portion 11 of the reactor 1. The solid material inlet 20 may be located in the side as showed or alternatively in the top. The solid material inlet 20 is suitable for allowing entry of carbonaceous material and/or a powder material into the reactor.

[0122] A gas outlet 26 is located in the upper portion 11 of the reactor 1 and a solid material outlet 21 is located in the lower portion 10 of the reactor 1. The solid material outlet 21 comprises adjusting means configured to adjust the level and/or amount of solid material in the reactor.

[0123] The reactor chamber 2 and the location of the solid material inlet 20, the gas outlet 26 and the solid material outlet 21 is arranged to provide gas-solid separation. In the particular embodiment this is achieved by having the gas outlet in the upper portion 11 and the solid material outlet in the lower portion 10 and located at different heights spaced so that the gas flow at the gas outlet has a velocity below an entrainment velocity.

[0124] During intended use a carbonaceous material having a conversion temperature is added to the reaction chamber 2 together with a powder material which has a temperature higher than the conversion temperature of the carbonaceous material. The solids may be pneumatically transported to the reactor chamber 2 or may be mechanically feed. In FIG. 1 both the powder material and the carbonaceous material are added through the solid material inlet 20, but they may also be added through different inlets as shown in FIG. 2. The reactor 1 is operated with an environment inside the reactor chamber 2 that is configured to no more than partially oxidize carbon to CO.sub.2. Preferably the ratio of oxygen to the total atmosphere in the reaction chamber (lambda) is below 0.15, such as below 0.12, preferably 0.05, more preferably 0.03.

[0125] The carbonaceous material and powder material falls downwards inside the reaction chamber 2 while contacting. As the carbonaceous material is heated to or above the conversion temperature, conversion of the carbonaceous material into a converted material and a volatile product takes place. The converted material will along with powder material and unconverted carbonaceous material fall further down towards the bottom of the reaction chamber 2. The adjusting means at the solid material outlet 21 adjust the amount of solid material in the lower portion 10 of the reactor chamber 2. This adjustment may be made according to a desired column height of the solid material and/or to obtain a desired retention time to allow the carbonaceous material to convert. The retention time should be at least 30 seconds, but depending on the specifications (type, size, conversion temperature etc.) of the carbonaceous fuel the retention time may be at least 120 seconds and up to around 600 seconds.

[0126] The volatiles converted from the carbonaceous material flow upwards towards the gas outlet 26 against the downwards flow of solids. This ensures better mixing and heat transfer between the solids. The dimensions of the reactor 1 is configured such that the gas velocity at the gas outlet 26 is below an entrainment velocity so that little or no solids are carried out through the gas outlet 26. The gas velocity can be controlled by adjusting the temperature in the reactor 1, adjusting the retention time or by adding a gas through a gas inlet 25.

[0127] Turning now to FIG. 2 showing a reactor 1 according to another embodiment of the invention. The reactor has a reactor chamber 2 having a lower portion 10 and upper portion 11. The flow area of the reaction chamber 2 increases in the upper portion 11 of the reactor chamber 2, due to an increasing cross-sectional dimension value (the diameter) of the reactor chamber 2. When the volatiles flow upwards from the lower portion 10 to the upper portion 11, the pressure and also the velocity of the gas is reduced below the entrainment velocity of the solids. In the embodiment shown the reactor 1 has two solid material inlets 20a and 20b, both located in the upper portion 11. Carbonaceous material may can be added to the reactor chamber 2 through material inlet 20a, which allows the carbonaceous material to heat exchange with the hot volatiles before it is contacted with the powder material entering the reactor chamber through solid material inlet 20b. The solid material outlet 21 is located in the lower portion 10 adjacent a fed screw 22. The fed screw 22 mechanically transports the solid material from the lower portion 10 of the reactor chamber 2. The rotational speed of the feed screw 22 may be adjusted to keep a steady level of solid materials in the reactor chamber 2.

[0128] Turning now to FIG. 3 showing the reactor 1 according to yet another embodiment of the invention, wherein the lower portion 10 of the reactor 1 has a fluid trap configuration in the form of a U-shape and the means for adjusting solid materials in the reactor 1 is one or more fluid inlets 25 configured to inject fluids and thereby fluidize the powder material. The reactor 1 comprises a first conduit 5 which seen in the cross sectional view has an essentially half annulus shape with its two opening oriented upwards. One end of the first conduit is fluidly connected to the lower portion of the reactor chamber 2. A second conduit 6 is oriented substantially vertical and has its lower end fluidly attached to the other end of the first conduit 5. The fluid inlets 25 are located in the bottom portion of the first conduit 5. By injecting fluid through the fluid inlets 25 and fluidizing powder material in the reactor 1 it is the weight of the material column in the reactor chamber 2 and second conduit 6 together with the location of the solid material outlet 21 that determines how much powder is in the reactor 1. The diameter in at least a part of the upper portion 11 is gradually increasing towards the top of the reactor chamber 2 to provide a conically shaped portion 15. This provides a gradually increasing flow area in the reactor chamber. It may be said the increase in flow area may be a sudden increase.

[0129] The method of converting carbonaceous material and the flow routes in the reactor 1 will now be described in more detail with reference to FIG. 4, which shows a reactor 1 comprising a bypass conduit 28 fluidly connecting the upper portion 11 of the reactor chamber 2 with upper end of the second conduit 6. A gas outlet 27 is located in the by-pass conduit 28.

[0130] During intended use, a carbonaceous material and a powder material is added to the reactor chamber 2 through the solid material inlet 20a, 20b and/or 20c. The Carbonaceous material has a conversion temperature and the powder material has a temperature higher than the conversion temperature. Once added to the reactor chamber 2 the carbonaceous material and the powder material is contacted and the carbonaceous material starts to convert into a converted material and a volatile product. The atmosphere inside the reactor chamber 2 is configured to no more than partially oxidize carbon to CO.sub.2. During use, solids (i.e. carbonaceous material, powder material, and converted material) falls due to gravity from the upper portion 11 towards the lower portion 10 and fill up the first conduit 5. By injecting a gas through the fluid inlets 25 the solids are fluidized and distributed between the lower portion 10 of the reactor chamber 2, the first conduit 5 and second conduit 6. The dotted lines 50 illustrates the column height of the solids in the situation where the fluidized column of solids in the reactor chamber 2 and the second conduit 6 has the same density, i.e. they are equally high. Below the dotted lines 50 the solids are present in a dense phase. The upper edge 51 in conduit 6 determines the height of the fluidized column of solids in the conduit 6 and thereby also height of the fluidized column of solids in the lower portion 10 of the reactor chamber 2. When solids build up further than the height 50, the solids flow through the first conduit 5 and second conduit 6 in a plug flow type pattern to above the upper edge 51 to adjust the equilibrium between the weight of the two fluidized columns of solids. The flow direction of the solids are indicted by the arrows mark with “S”. The conversion of the carbonaceous material into volatiles and converted material take place in both the reactor chamber 2, the first conduit 5 and second conduit 6. The flow direction of the volatiles and fluidization gases are indicated by the arrows mark with (G). Due to the development of volatiles the upwards gas flow in the lower portion 10 of the reactor chamber 2 typically has a velocity higher than the entrainment velocity of the solids. Solids are therefore picked-up by the gases and lifted upwards towards to upper portion 11 of the reactor chamber 2 forming an area in the reactor chamber with a low concentration of solids, i.e. a diluted zone. This zone is located above the dotted line 50. When the gases and solids reach the conically shaped portion 15, the velocity drops below the entrainment velocity and the solids may no longer be suspended by the gas. This provides a spouting zone where solids again fall downwards towards the lower portion 10 of the reactor chamber 2 and the gas continues upwards substantially free from solids. This flow of solids is similar to a fountain and is illustrated by the arrows “S” in the upper portion 11 of the reactor chamber 2. During operation the solids will flow in several directions as illustrated by the arrows marked with “S”, but looking from an overall material balance view the solids will move from the upper portion 11 through the lower portion 10, the first conduit 5 and the second conduit 6.

[0131] Any volatiles which are developed in the second conduit 6 will flow upwards together with the solids. Once the flow of solids and gas pass the upper edge 51, the substantially all solids will flow through the solid material outlet 21 while the gases will continue upwards through the by-pass conduit 28 towards the gas outlet 26 and/or 27.

[0132] The gas provided through the fluid inlet 25 is preferably provided in pulses providing a more efficient fluidization with less amount of gas. The gas may comprise a reactant gas, an inert gas or combinations thereof.

[0133] Turning now to FIG. 5 showing a reactor 1 according to yet another embodiment, wherein the second conduit 6 has an increase in flow area. The increase in flow area may be a graduate increase or a sudden increase which allows the velocity of any gas flow in the second conduit to decrease to below the entrainment velocity of the solids. The embodiment shown in FIG. 5 has two spouting zones. This is beneficial when only partial conversion of the carbonaceous material takes place in the reactor chamber 2 and when significant conversion might take place in the first conduit 5 or even second conduit 6. If the second conduit 6 is not properly sized to contain the developed volatiles, the development of volatiles may result in a gas velocity above the entrainment velocity of the solids. This results in that the dense phase in the second conduit 6 becomes diluted and an undesired flow pattern involving a flow of volatiles and solids to the gas outlet 27. By increasing the cross-sectional dimension of a portion the second conduit 6 to provide a portion having an increased flow area a spouting and settling zone is established where entrained powder drops out and eventually spills over the edge 51 towards the solid material outlet 21. This results in a stable solids stream from the reactor chamber 2 to the outlet 21, which significantly improves the operation of the overall process and allows for smaller sizing of the second conduit 6. If the reactor 1 is operated with easily convertible carbonaceous material the development of volatiles essentially takes place in the reactor chamber 2. In this situation the embodiment of FIG. 4 may be sufficient for stable operation. If the reactor 1 is operated with larger pieces of carbonaceous material or carbonaceous material which is harder to convert, the development of volatiles may take place through the entire reactor or even mainly in the second conduit. In this situation a spouting zone and settling zone in the second conduit, or in both the reactor chamber 2 and the second conduit 6 is beneficial for stable operation of the reactor 1.

[0134] Turning now to FIG. 6 showing the reactor 1 according to yet another embodiment wherein the first conduit 5 has a so-called extended radius design. It can be seen that the cross-sectional value (i.e. the distance) between the upper conduit wall 32 and lower conduit wall 31 varies through the first conduit 5. A mesh 30 is optionally located in the first conduit 5 at a constant distance from the upper conduit wall 32. This provides a solid free void 35 below the mesh 30. The mesh ensures that the solids are not in direct contact with the lower conduit wall 31. When reactant gas is provided through the fluid inlets 25, a localized temperature increase may be seen due to oxidizing of the carbonaceous material. The mesh 30 ensures that the lower conduit wall 31 is not damaged by the elevated temperatures, e.g. due to material build-ups or high-temperature corrosion which can be expected when firing with alternatives fuels comprising chlorides and/or sulfur. The mesh 30 is easy replaceable compared to the first conduit 5.

[0135] The reactor 1 shown in FIG. 5 only has the gas outlet 27. Volatiles and reactant gas from the reactor chamber 2 will therefore flow from the upper portion 11 of the reactant chamber 2 through the by-pass conduit 28 towards the gas outlet 27.

[0136] Turning now to FIG. 7 showing the reactor 1 installed in connection with a pre-heater tower 100, calciner 110, and a kiln 120 of a cement clinker manufacturing plant. The kiln 120 and the calciner 110 is connected by a kiln riser 115. Cement raw meal is fed to the raw meal inlet of the uppermost stage preheater cyclone 150d. From that point the raw meal flows towards the rotary kiln 120 through the cyclones of the preheater and the calciner 110 in counter flow to hot exhaust gases from the rotary kiln 120, thereby causing the raw meal to be heated and calcined. Calcined meal is directed from calciner 110 to bottom stage cyclone 150a where the calcined meal is separated from calciner exhaust gas. The calcined raw meal is burned into cement clinker in the rotary kiln 120, and the cement clinker are cooled in the subsequent clinker cooler by means of atmospheric air (not shown). Some of the air thus heated is directed from the clinker cooler via a duct to the calciner 110 as so-called tertiary air (not shown).

[0137] The reactor 1 is located adjacent to the calciner 110 and the kiln riser 115 and is optionally positioned so that hot cement meal will move by gravity from the cyclone stage 150b. Hot cement meal from 150b is split between the reactor 1, the kiln riser 115, and the calciner 110 in an adjustable ratio between 0 to 100%. The amount of hot cement meal diverted to reactor 1 will depend upon input rate and conversion time of the alternative fuel. The balance of hot cement meal will be split between the kiln riser 115 and the calciner 110. Typically, 50 to 70% of the hot cement meal is directed to the calciner 110 and the majority of the remaining is sent to reactor 1. The hot cement meal from cyclone 150b will typically have a temperature in the range of 730-830° C. The hot cement meal from 150b preferentially passes through a loop seal 130 that functions as a gas barrier that in essence prevents conversion products flowing into 150b as well as prevents gases from 150b to flow into reactor 1.

[0138] The unconverted alternative fuel and the hot cement meal is directed into the pyro system, most preferably to the calciner 110 via the kiln riser 115. Some or all of the conversion products from reactor 1 can be introduced into the kiln riser 115 to create a reduction zone to reduce the NOx produced in kiln 120 or be introduced directly into the calciner 110. In another embodiment, some or all the conversion products i.e. volatile gases, from reactor 1 can be utilized in the rotary kiln burner. In a further embodiment, some or all of the conversion products gas can be utilized outside of the cement process, such as in a process to make combustible gases.

[0139] Alternatively, hot cement meal can be diverted from other cyclones in the preheater, such as from 150c or 150a, into the reactor 1. The hot cement meal is optionally passed through a loop seal 130 that functions as a gas barrier to the material inlet of reactor 1. The bottom of the loop seal might optionally be equipped with a bottom outlet for oversized particles, which may in turn be connected to the kiln riser 115, kiln inlet or to a separate container.

[0140] Preheaters can be designed in a multitude of configurations with variations in number of cyclones with full or partial split of gas, as well as solids, between the individual cyclones. In some cases, it might be preferable to take a part of the solid from other cyclones or a mixture thereof of in order to obtain desired process conditions in the calciner 110.

[0141] The calciner 110 configuration depicted in FIG. 6 is a so-called “in-line calciner” system in which the calciner is positioned relative to the kiln riser 115 so all of the kiln exhaust gases pass through the calciner 110. The method of the present invention can also be effectively used with other configurations, including “separate line calciner” systems in which the calcining chamber is at least partially offset from the kiln riser 115 so that kiln combustion gases do not pass through the calciner, and where the combustion air for the calciner is drawn through a separate tertiary air duct.