Flash pyrolosis method for carbonaceous materials
Methods are disclosed for pyrolizing carbonaceous materials to carbonaceous materials having lower boiling points by heating the carbonaceous material to a desired reaction temperature and holding the carbonaceous material in contact with the heat for a sufficient time to achieve the desired reaction to a lower boiling point carbonaceous materials, then rapidly cooling the desired reaction products. The heating source is a jet which will provide hot and high velocity gas streams to the carbonaceous material to be heated.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/808,647 filed May 26, 2006.
BACKGROUND OF THE INVENTIONThis invention relates to the purification of streams containing carbon monoxide and more particularly to the removal of low molecular weight hydrocarbons (e.g., methane) from a carbon monoxide stream by adsorption at cryogenic temperatures.
Carbon monoxide (CO) is a major building block for the chemical industry. Besides use as an intermediate in the production of acetic acid, formic acid, and dimethyl formamide to name a few, CO is also a key raw material in the production of phosgene. Phosgene is a key intermediate in many chemical industries, namely polycarbonates, polyurethanes, agricultural chemicals and fine chemicals (pharmaceutical). During the production of phosgene, a CH4 concentration in the CO of more than 100 ppm is detrimental to the overall process from a standpoint of purity, recovery and environmental emissions. Current industry/customer purity requirements are for a methane concentration around 20 ppm or less.
The production of carbon monoxide involves conventional techniques such as steam methane reforming, partial oxidation of hydrocarbons, methanol cracking, and CO2 reforming. In the steam reforming process, hydrocarbons such as methane are converted to syngas, a mixture of carbon monoxide, carbon dioxide, hydrogen and water, through the clearly show that the distillate yield from a very wide range of thermal processes and feedstocks increase with increasing operating temperature. For example, U.S. Pat. No. 4,446,004 teaches thermal cracking of a hydrotreated resid feed at high temperature and short residence time to maximize the distillate yield. U.S. Pat. No. 4,698,147 teaches that a hydrogen donor thermal cracking process can also achieve maximum resid conversion distillates by operating at a high temperature and short residence time. However, the maximum temperature and minimum residence time of this process was limited to 525° C. and three minutes by the maximum heat flux that can be achieved with fired heater. As a result, resid conversion in thermal cracker and delayed coker unit operations are typically limited by the maximum temperature and heat flux that can be achieved in a fired heater.
U.S. Pat. No. 2,906,695 teaches that much higher thermal cracking and coking temperatures can be achieved by contacting the residual oil feed with a stream of hot coke particles. As expected, fluidized bed cokers typically achieve higher distillate yields than delayed cokers. However, one disadvantage of the fluidized bed coker is the coke product is much more difficult to grind and burn than the delayed coke product. Clearly, one would prefer to achieve a high distillate yield with a less problematic by-product. Better yet, one would like to achieve higher distillate yields with little or no coke production.
Fluid catalytic cracking unit operations use hot catalyst to rapidly heat the oil feed to cracking temperatures to increase process efficiency. U.S. Pat. No. 5,662,868 teaches that a shorter residence time is advantageous for cracking more carbonaceous feedstocks. Canadian Patent Application No. 02369288 teaches higher temperatures and shorter residence times maximize the heavy oil or bitumen conversion to distillates by contact with a hot particulate sand stream.
Thermal cracking and coking kinetic models also provide insights into the effect of high temperature and short residence time cracking.
can be used as a crude measure of process operability and quality of the heavy residual oil by-product. A lower
ratio would be generally be associated with more reliable thermal cracking process operations and a higher quality heavy residual oil product. The results in
ratio of 2. However, this benefit would require much more rapid heating and cooling rates than can be achieved using conventional means.
Other process developers reached similar conclusions with regards to coal feeds. U.S. Pat. No. 4,545,890 teaches that the distillate yield from a hydrogen donor coal liquefaction process increases with increasing temperature and decreasing residence time. U.S. Pat. No. 4,048,053 teaches that the maximum distillate yield can by achieved by contacting coal with hot hydrogen at a temperature greater than 400° C. and residence time between 2 milliseconds and 2 seconds. U.S. Pat. No. 5,110,452 maximizes distillate yield by heating to 1000° to 2000° F. (538 to 1093° C.) at a rate greater than 10,000° F./second (5,538° C./second) with a hot gas from a partial oxidation unit operation. Once again, the potential benefits are relatively clear if a reliable and cost-effective method can be found to achieve the required high heating rates.
Super sonic hot gas jets have been used to achieve very high heating rates in other applications. For example, U.S. Pat. No. 6,910,431 teaches a method to use oxygen-fuel combustion to produce supersonic jets to rapidly heat surfaces.
The calculations in
The present invention provides for a method to use an annular hot, high velocity gas stream to rapidly heat a coaxial carbonaceous stream.
This invention utilizes hot supersonic jets with appropriate shape, mechanical energy, and thermal energy to achieve the rapid heating rate indicated on
In one embodiment of the present invention, there is disclosed a method for the conversion of a carbonaceous feed material to a carbonaceous material with lower normal boiling point comprising means to
-
- a) produce a hot gas at elevated pressure;
- b) convert said hot gas at elevated pressure to a hot high velocity gas jet or array of jets at lower pressure;
- c) feed carbonaceous feed material mesial to the hot, high velocity jet or array of jets to rapidly heat the carbonaceous feed material;
- d) provide sufficient residence time to achieve the desired conversion of the carbonaceous feed material to lower boiling point material; and
- e) rapidly cool the lower boiling point material reaction products.
In a further embodiment of the present invention, there is disclosed a pyrolysis process for converting a feed carbonaceous material having a first boiling point to a carbonaceous material having a second lower normal boiling point comprising the steps:
-
- a) heating said feed carbonaceous material to a desired reaction temperature;
- b) cooling the reaction products produced in step (a); and
- c) recovering said reaction products.
In a further embodiment of the present invention, there is disclosed a process for converting a feed carbonaceous material having a first normal boiling point to a carbonaceous material having a second lower normal boiling point comprising directing a high velocity hot gas stream to said feed carbonaceous material, cooling the reaction products of the heating of said feed carbonaceous material, and recovering said reaction products.
The calculations in
The carbonaceous material feed S1 can be any material that contains carbon. It may include gaseous, liquid, or solid carbon containing material or mixtures in any proportion. A residual carbonaceous material has some species with a normal boiling point greater than 524° C. Carbonaceous material species with normal boiling points less than 524° C. are considered distillates. A liquidus residual carbonaceous material contains some species with normal boiling points greater than 524° C. with an apparent viscosity less than or equal to 1000 centipoises at 300° C. Petroleum resid, petroleum tar, coal tar, bitumen, and by-products from catalytic or non-catalytic cracking processes are representative examples of residual liquid carbonaceous feed materials. Solid carbonaceous material has an apparent viscosity greater than 1000 centipoises. Coal and oil shale are representative examples of solid carbonaceous feed materials. The solid carbonaceous material feed would typically be admixed with a gaseous and/or liquid carrier material. Typical gaseous carrier materials for solid carbonaceous materials could include hydrocarbon molecules with less than eight carbon atoms per molecule, steam, nitrogen, and argon in any proportion. Liquid carrier materials for solid carbonaceous materials could include petroleum liquids, coal derived liquids, or water in any proportion. Typical examples of gaseous carbonaceous feed materials would include ethane, propane, and butane for the production of hydrogen and the corresponding olefin.
The fuel feed S2 may be any material with a heat of combustion with air at 25° C. and 1 atmosphere that is greater than 5,000 joules per gram of fuel. The fuel feed is preferably a gas or a liquid. Typical gaseous fuel feeds would include any hydrocarbon mixture at a temperature that is above its dew point at the burnjector operating pressure and less than 400° C. A hydrocarbon is any species that contains some carbon and hydrogen atoms. Hydrocarbons would typically also contain some sulfur, oxygen, and nitrogen atoms. Carbon monoxide and hydrogen are useful examples of gaseous non-hydrocarbon fuels. Liquid fuel feed would include any mixture of hydrocarbon species that are fed to the burnjector lance at a temperature below its bubble point temperature at the burnjector operating pressure. Solid fuels are preferably converted to gaseous or liquid fuels via gasification, or similar process, prior to feeding to the burnjector lance.
The oxidant S3 feed is preferably substantially pure oxygen, which is preferably greater than 70 molar percent O2, more preferably greater than 90 molar percent O2, and most preferably greater than 95 molar percent O2. The burnjector lance S4 coolant is preferably, water, steam, or steam with a water mist.
The fuel feed S2 enters the burnjector lance though a conduit 7 that is in flow communication with the fuel feed S2 radial distribution header 8. A conduit 9 maintains flow communication between the fuel feed S2 radial distribution header 8 and the annular combustion chamber 6. The cross-sectional area of the fuel S2 radial distribution header 8 is sufficient to maintain a substantially uniform pressure at the proximal end of the fuel feed conduit 9 to the annular combustion chamber 5. The fuel feed conduit may be a continuous curvilinear conduit (as shown on
Any conventional means may be used to initiate combustion. For example, one may use a spark ignition source to initiate and maintain combustion. Alternatively, one may preheat the S2 fuel stream to a temperature above its auto thermal ignition temperature at the burnjector operating oxygen partial pressure to ensure prompt ignition and reliable combustion. In addition, species with low auto thermal ignition temperatures, e.g., hydrogen sulfide, may be advantageously added to the S2 fuel feed stream, at start-up or during normal operations, to facilitate ignition and to stabilize the flame S5. Alternatively a catalyst may be added to lower the auto ignition temperature. In this case a portion or all of the S4 coolant stream would preferably be added to S2 fuel and/or the S3 oxidant streams to control the adiabatic flame temperature. With a vapor S2 fuel; this catalytic combustion system would be similar to catalytic combustion systems used in stationary natural gas turbines for the production of electrical energy. With a liquid S2 fuel, this catalytic combustion system would be similar to catalytic combustion systems used in aircraft fan jet engines. Either catalytic combustion system could be used to preheat the S2 fuel and/or the S3 oxidant stream to a temperature in excess of the auto thermal ignition temperature to ensure stable combustion in a subsequent non-catalytic combustion step. The S2 fuel and S3 oxidant feeds are contacted for a sufficient time to substantially complete combustion, typically between 10 millisecond and 2 seconds.
The burnjector S4 coolant feed stream typically enters the burnjector inner body 2 at the proximal end 3 through conduit 13 and flows into the inner body 2 S4 coolant feed radial header 14. The cross-sectional area of the S4 coolant radial header 14 is sufficient to provide an essentially constant pressure at the proximal end of coolant conduit 15. The S4 coolant leaves the S4 coolant radial header 14 and flows axially in conduit 15 toward the distal end 4 of the burnjector lance. Then, the coolant flows in 16 toward the burnjector proximal end 3 to the inner body 2 coolant product radial header 17. The coolant in conduits 15 and 16 prevent overheating and coking of the carbonaceous material feed S1 in the burnjector central conduit 23. One can improve the temperature control by using a saturated steam-water mist burnjector S4 coolant stream. The coolant flows from the inner body 2 coolant product radial header 17 to the outer body 1 coolant feed radial header 19 via conduit 18. Then the S4 coolant flows axially in conduit 20 toward the distal end 4 of the burnjector and then flow axially in conduit 21 toward the proximal end 3 of the burnjector. The S4 coolant can optionally be discharged from the proximal end of the burnjector. However, the preferred embodiment of this invention is to discharge the S6 heated coolant through nozzle 22 in the annular combustion chamber 5. Then, the heated coolant stream 6 combines with the combustion products S5 to form the convergent-divergent nozzle 6 feed S7. The temperature of the convergent-divergent nozzle 6 feed S7 is preferably between 3500° and 1000° C., more preferably between 2500° and 1250° C., most preferably between 1500° and 2000° C. The ratio of the convergent-divergent nozzle 6 feed S7 pressure to S10 reactor exit pressure is preferably between 2:1 and 20:1, more preferably between 2:1 and 10:1, most preferably between 3:1 and 5:1.
Earlier processes provide guidance (see for example, Robert H. Perry & Cecil H. Chilton, “The Chemical Engineer's Handbook,” 5th Edition, McGraw Hill (New York), 1973, p. 5-29) for designing and estimating the performance of convergent-divergent nozzles. The burnjector may be equipped with a curvilinear convergent-divergent nozzle 6 as shown in Section B-B on
The burnjector lance may also be equipped with an array of discrete convergent-divergent nozzles as shown in B-B′ section on
Clearly, there are many other burnjector mechanical designs that are capable of producing hot and high velocity gas stream S8 that can rapidly heat the carbonaceous stream S9. One could advantageously change the dimension of the burnjector lance. For example, one could decrease the combustion chamber surface to volume ratio and heat transfer to the burnjector outer body 2 and inner body 1 by increasing the burnjector diameter to length ratio at constant gas residence time in the combustion chamber. One could also produce the S8 and S9 stream configuration using a substantially different burnjector configuration. For example, one could utilize a cylindrical combustion chamber, rather than the annular combustion chamber shown on
The burnjector coolant S4 coolant feed provides cooling for the burnjector lance outer body 1 and inner body 2. The S4 coolant feed rate also affects the thermal and mechanical energy content of the stream S8 jet.
The flash pyrolysis system 30 uses the combination of a burnjector lance 1, reactor 25, and quench zone 26 to achieve high-temperature and short residence time thermal cracking operating conditions. The reactor 25 is preferably refractory 26 lined to prevent overheating of cylindrical wall. The reactor preferably has a height to diameter ratio greater than 1:1, more preferably greater than 5:1, most preferably greater than 10:1. The reactor 25 preferably has a cylindrical cross section.
The reactor operating temperature is preferably in the 500° to 1000° C. temperature range, more preferably in the 550° to 900° C. temperature range, most preferably in the 600° C. to 800° C. temperature range. The reactor 25 operating pressure is preferably in the 0.2 to 6 bar range absolute pressure range, more preferably in the 1 to 5 bar absolute pressure range relative, most preferably in the 2 to 3 bar absolute pressure range. The ratio of the absolute pressure of the combustion chamber 5 of the burnjector lance 1 to the pressure of reactor 25 is preferably between 2:1 and 20:1, more preferably between 2:1 and 10:1, most preferably between 3:1 and 5:1. The reactor operates with a steam partial pressure preferably greater than 0.1 bar, more preferably greater than 0.5 bar, and most preferably greater than 1 bar. Steam has two functions in the pyrolysis reactor 25. First, steam is known to decrease the coking rate by termination of free radical polymerization reactions. Second, steam can remove soot from the pyrolysis reactor walls via a well established reaction [2H2O (g)+C→CO2(g)+4H2(g)] at the pyrolysis reactor operating conditions.
The residence time in the reactor 25 is limited to ensure that the mass fraction of the material in the S1 feed with normal boiling points greater than 524° C. that is converted to material with normal boiling points less than 524° C. is preferably in the 0.5 to 0.95 range, more preferably in the 0.6 to 0.9 range, most preferably in the 0.7 to 0.85 range.
A conventional phase separator 27 is used to remove the resulting heavy oil S13 stream. The remaining vapor product S12 may be advantageously used to produce S4 steam coolant stream for the burnjector lance 1 and S15 export steam. A mist generator 29 may be advantageously used to improve the temperature control of the burnjector inner body 2. A portion of the unconverted residual material in the heavy oil S13 may be advantageously recycled to the carbonaceous feed S1. The balance of the unconverted residual material may advantageously be used to produce hydrogen, using standard partial oxidation and purification techniques, to upgrade the distillate products.
One may increase the maximum achievable distillate yield by hydrogenation of the liquid carbonaceous material S1 or adding a hydrogen donor solvent to the S1 feed. With solid carbonaceous feeds, like coal, the addition of substantial quantities of hydrogen is required to achieve commercially attractive distillates yield.
Table 1 summarizes the vacuum bitumen resid feed properties. Table 2 presented below shows a component material balance for flash pyrolysis system treating 10,000 barrels per day of the bitumen in Table 2.
This example selects operating conditions capable of achieving 85 weight percent conversion of species in the feed with normal boiling points greater than 525° C. to species with boiling points less than 525° C. with toluene insoluble production equal to the feed toluene insoluble content. For comparison, high performance coking processes would a coke yield ≧25 weight percent of the resid feed in Table 1. The spatial efficiency of refining unit operations are usually express in terms of liquid hourly space velocity, the ratio of the volume of oil treated per hour to the reactor volume. In this example, the flash pyrolysis reactor has a space velocity of 6.4 hours−1, which is much greater than conventional thermal cracking or coking processes. The unconverted residual oil from the flash pyrolysis reactor is advantageously used to produce hydrogen, using standard partial oxidation and purification techniques, to upgrade the distillate products. The partial oxidation plants treating liquid carbonaceous feeds are substantially less costly and troublesome than the corresponding plant treating a solid carbonaceous feed.
While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of the invention will be obvious to those skilled in the art. The appended claims in this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention.
Claims
1. A method for the conversion of a carbonaceous feed material to a carbonaceous material with lower normal boiling point comprising means to
- a) produce a hot gas at elevated pressure;
- b) convert said hot gas at elevated pressure to a hot high velocity gas jet or array of jets at lower pressure;
- c) feed carbonaceous feed material mesial to the hot, high velocity jet or array of jets to rapidly heat the carbonaceous feed material;
- d) provide sufficient residence time to achieve the desired conversion of the carbonaceous feed material to lower boiling point material; and
- e) rapidly cool the lower boiling point material reaction products.
2. The method as claimed in claim 1 wherein said carbonaceous feed material has components with normal boiling point greater than 524° C.
3. The method as claimed in claim 1 wherein said carbonaceous feed material is selected from a material consisting essentially of heavy crude oil, petroleum resid, petroleum tar, coal tar, bitumen, coal, oil shale and mixtures thereof.
4. The method as claimed in claim 1 wherein said carbonaceous material with a lower normal boiling point is selected from a material consisting essentially of distillates.
5. The method as claimed in claim 1 wherein said hot high velocity gas stream is between 500° C. and 2500° C.
6. The method as claimed in claim 1 wherein said jet or array of jets is a burnjector lance.
7. The method as claimed in claim 1 wherein said sufficient residence time is sufficient to convert between about 0.5 and 0.95 mass fraction of the residual heavy oil feed to distillates
8. The methods claimed in claim 1 wherein said reaction products are rapidly cooled by distillate carbonaceous material, water, steam or a mixture thereof.
9. The method as claimed in claim 1 wherein said reaction products are cooled to a temperature of less than about 400° C.
10. The method as claimed in claim 1 wherein the velocity of said hot high velocity gas is greater than 500 meters per second.
11. The method as claimed in claim 1 wherein said hot gas is produced by combustion of a fuel with substantially pure oxygen.
12. The method as claimed in claim 11 wherein said substantially pure oxygen contains greater than 70 mole percent oxygen.
13. The method as claimed in claim 1 wherein the pressure ratio of said hot gas to said reaction product is between 20:1 and 2:1
14. A pyrolysis process for converting a feed carbonaceous material having a first boiling point to a carbonaceous material having a second lower normal boiling point comprising the steps:
- a) heating said feed carbonaceous material to a desired reaction temperature;
- b) cooling the reaction products produced in step (a); and
- c) recovering said reaction products.
15. The process as claimed in claim 14 wherein said heating is provided by a hot high velocity jet or an array of jets.
16. The method as claimed in claim 14 wherein said carbonaceous feed material has components with normal boiling points greater than 524° C.
17. The method as claimed in claim 14 wherein said carbonaceous feed material is selected from a material consisting essentially of heavy crude oil, petroleum resid, petroleum tar, coal tar, bitumen, coal, oil shale, and mixtures thereof.
18. The method as claimed in claim 14 wherein said carbonaceous material with a lower normal boiling point is selected from a material consisting essentially of distillates.
19. The method as claimed in claim 15 wherein said hot high velocity gas stream is between 500° C. and 2500° C.
20. The method as claimed in claim 15 wherein said jet or array of jets is produced by a burnjector lance.
21. The method as claimed in claim 14 wherein said reaction products are rapidly cooled by distillate carbonaceous material, water, steam or a mixture thereof.
22. The method as claimed in claim 14 wherein the velocity of said hot high velocity gas is greater than 500 meters per second.
23. The method as claimed in claim 14 wherein said hot gas is produced by combustion of a fuel with substantially pure oxygen.
24. The method as claimed in claim 23 wherein said substantially pure oxygen contains greater than 70 mole percent oxygen.
25. The method as claimed in claim 18 wherein sufficient residence time is allowed after step (a) to convert between about 0.5 and 0.95 mass fraction of the residual heavy oil feed to distillates
26. A process for converting a feed carbonaceous material having a first normal boiling point to a carbonaceous material having a second lower normal boiling point comprising directing a high velocity hot gas stream to said feed carbonaceous material, cooling the reaction products of the heating of said feed carbonaceous material, and recovering said reaction products.
27. The method as claimed in claim 26 wherein said carbonaceous feed material has components with normal boiling point greater than 524° C.
28. The method as claimed in claim 26 wherein said carbonaceous feed material is selected from a material consisting essentially of heavy crude oil, petroleum resid, petroleum tar, coal tar, bitumen, coal, oil shale and mixtures thereof.
29. The method as claimed in claim 26 wherein said carbonaceous material with a lower normal boiling point is selected from a material consisting essentially of distillates.
30. The method as claimed in claim 26 wherein said hot high velocity gas jet is between 500° C. and 2500° C.
31. The method as claimed in claim 26 wherein said heat is provided by a jet or array of jets.
32. The method as claimed in claim 26 wherein said jet or array of jets is produced by a burnjector lance.
33. The method s claimed in claim 26 wherein said reaction products are rapidly cooled by distillate carbonaceous material, water, steam or a mixture thereof.
34. The method as claimed in claim 26 wherein the velocity of said hot high velocity gas is greater than 500 meters per second.
35. The method as claimed in claim 26 wherein said hot gas is produced by combustion of a fuel with substantially pure oxygen.
36. The method as claimed in claim 34 wherein said substantially pure oxygen contains greater than 70 mole percent oxygen.
37. The method as claimed in claim 29 wherein sufficient residence time is allowed after step (a) to convert between about 0.5 and 0.95 mass fraction of the residual heavy oil feed to distillates
Type: Application
Filed: Feb 22, 2007
Publication Date: Nov 29, 2007
Inventor: Donald P. Satchell (Chatham, NJ)
Application Number: 11/709,546
International Classification: C10B 49/02 (20060101);