Patent Application
20070272538
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.
1Cut 1 at 0 degree F. and 1 atm reference state and 0 KJ/gm-mole C—C bond heat of reaction for hydrocarbon fractions
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.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/808,647 filed May 26, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60808647 | May 2006 | US |
