A flexible approach to partial oxidation

Abstract

A method of using a hot oxygen generator to respond to changes in the characteristics of a feed to a partial oxidation reactor is disclosed.

Description

Technical Field

[0001] The present invention relates to the production of hydrocarbon feedstocks by a process utilizing partial oxidation ("POx") of hydrocarbon feed materials. Background Art

[0002] Plants for producing hydrocarbon products from hydrocarbon feed materials are typically operated within predetermined conditions based on a set of assumed properties including those of the feed material and based on the desired properties of the products produced. However, when there is a change in the properties of the feed material (including intrinsic properties, such as its composition, but also extrinsic properties, such as its feed rate), operators are typically forced to interrupt operations and / or set up expensive alternative processes to accommodate the change.

[0003] This general type of process that may be susceptible to such damage is described in U.S. Pat. No. 9,624,440 and U.S. Published Patent Application No. US2016 / 0102259. The applicability of this type of process is described in U.S. Pat. No. 9,290,422, which discloses a device such as an autothermal reactor ("ATR") added to a device already in place to produce liquid fuels from source materials.

[0004] The present invention increases the flexibility and operating efficiency of a process for producing hydrocarbon feedstocks that can be used to produce products such as fuels. Summary of the invention

[0005] A first aspect of the present invention is a method for producing a hydrocarbon feedstock, the method comprising:

[0006] (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed may optionally contain tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen such that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed while converting tar, if present in the raw feed, to lower molecular weight products comprising hydrogen and CO, thereby producing a hydrocarbon feedstock having a molar ratio of hydrogen to CO at a first value;

[0007] (B) replacing the original feed fed to the partial oxidation reactor with a regulated feed fed to the partial oxidation reactor, and said replacement is effected by: (i) reducing or interrupting the amount of the original feed from the source of the original feed fed to the partial oxidation reactor; and (ii) feeding to the partial oxidation reactor a hydrocarbon feed stream that is not from the source of the original feed and has a composition different from the composition of the original feed, and continuing to feed to the partial oxidation reactor an oxygen stream having a temperature of 2000F to 4700F, wherein reaction of the regulated feed with the oxygen in the partial oxidation reactor under the conditions under which the original feed reacted with the oxygen in step (A) produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a second value different from the first value, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor such that its reaction with the regulated feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a third value different from the second value; and then

[0008] (C) completely replacing the adjusted feed fed in step (B) with all of the original feed from the source fed to the partial oxidation reactor, while continuing to feed an oxygen stream having a temperature of 2000F to 4700F to the partial oxidation reactor, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor relative to the conditions employed in step (B) so that its reaction with the original feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is different from the third value.

[0009] In a preferred embodiment of this aspect of the invention, in step (B) the amount of oxygen that has been used to produce the original feed is fed to the partial oxidation reactor to increase the output of the partial oxidation reactor.

[0010] One embodiment of the foregoing method utilizing the WGS reaction is a method of producing a hydrocarbon feedstock, the method comprising:

[0011] (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed may optionally contain tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen such that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed while converting tar, if present in the raw feed, into lower molecular weight products comprising hydrogen and CO, and recovering an intermediate feed stream from the partial oxidation reactor;

[0012] (B) catalytically adjusting the molar ratio of hydrogen to CO in the intermediate feed stream from step (A) to produce a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a first value;

[0013] (C) replacing the original feed fed to the partial oxidation reactor with a conditioned feed fed to the partial oxidation reactor, the replacement being effected by: (i) reducing or interrupting the amount of the original feed from the source of the original feed fed to the partial oxidation reactor; and (ii) feeding to the partial oxidation reactor a hydrocarbon feed stream that is not from the source of the original feed and has a composition different from the composition of the original feed, and continuing to feed to the partial oxidation reactor an oxygen stream having a temperature of 2000F to 4700F, wherein reaction of the conditioned feed with the oxygen in the partial oxidation reactor under the conditions under which the original feed reacted with oxygen in step (A) and subsequent catalytic conditioning under the conditions employed in step (B) produces a hydrocarbon product in which the molar ratio of hydrogen to CO is at a second value, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor such that its reaction with the conditioned feed and subsequent catalytic conditioning produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at the second value; and then

[0014] (D) completely replacing the adjusted feed fed in step (C) with all of the original feed from the source fed to the partial oxidation reactor, while continuing to feed an oxygen stream having a temperature of 2000F to 4700F to the partial oxidation reactor, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor relative to the conditions employed in step (C) such that its reaction with the original feed and subsequent catalytic adjustment produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is different from the second value.

[0015] A second aspect of the present invention is a method for producing a hydrocarbon feedstock, the method comprising:

[0016] (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed may optionally contain tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen such that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed, while converting tar, if present in the raw feed, to lower molecular weight products comprising hydrogen and CO, and recovering an intermediate feed stream from the partial oxidation reactor in which the molar ratio of hydrogen to CO is within a given range;

[0017] (B) generating steam by heating liquid water in indirect heat exchange with said intermediate feed stream produced in step (A);

[0018] (C) feeding the steam and the carbonaceous feed material produced in step (B) to a reactor to produce a second raw feed by interaction of the steam with the carbonaceous feed material, the second raw feed may optionally contain tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof; and

[0019] (D) replacing the original feed fed in step (A) with the second original feed fed to the partial oxidation reactor, while continuing to feed an oxygen flow having a temperature of 2000F to 4700F into the partial oxidation reactor so that its reaction with the second original feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is within the given range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow diagram of a facility for producing hydrocarbon liquids, such as fuels, from feedstocks, such as biomass.

[0021] Figure 2 is a cross-sectional view of an apparatus that can be used in the present invention to produce a hot oxygen flow.

[0022] Figure 3 yes Figure 1 A cross-sectional view of a portion of a process flow diagram. DETAILED DESCRIPTION

[0023] The present invention is particularly applicable to operations that convert hydrocarbon products such as biomass into useful hydrocarbon products such as (but not limited to) liquid fuels. The raw materials produced by the present invention include products that can be sold and used as they are, and products that can be used as reactants to produce other finished useful products that can be subsequently sold and used.

[0024] Figure 1 is a process flow diagram showing typical steps for such operations.

[0025] refer to Figure 1 , a stream 1, also referred to herein as raw feed, is fed to a partial oxidation reactor 4. Stream 1 is provided by a source 11, which represents a production facility or reactor in which feedstock 1 is produced.

[0026] Examples of suitable raw feedstocks 1 and sources 11 thereof include:

[0027] natural gas, from any commercial source thereof;

[0028] a gaseous stream produced by a gasification reactor in which solid hydrocarbon material such as biomass or solid fuels such as coal or lignin are gasified in a gas stream, usually comprising air, steam and / or oxygen, at a sufficiently high temperature that at least a portion of the solid material is converted into a gaseous raw stream 1;

[0029] product and by-product streams, which are more typically gaseous, but can be liquid and / or solid, produced in a petrochemical refinery or chemical plant;

[0030] coke oven gas, which is a waste gas stream produced in a reactor that processes coal to produce coke;

[0031] Pyrolysis gas, a gaseous stream containing hydrocarbons, produced in a reactor to thermally treat solid carbonaceous materials such as fossil fuels or biomass, thereby removing volatile components and partially oxidizing the solid materials;

[0032] Other possible feed streams include oils, such as pyrolysis oils, and liquid hydrocarbons.

[0033] The raw feed 1 typically contains hydrogen and carbon monoxide (CO), and typically also contains one or more hydrocarbons, such as alkanes and / or alkanols having 1 to 18 carbon atoms, and typically contains carbon dioxide (CO2) and one or more of the higher molecular weight hydrocarbons characterized as tar and / or soot.

[0034] The raw feed stream 1, if heated as it leaves the source 11, typically exhibits a temperature between about 500°F and 1600°F.

[0035] The raw feed stream 1 is then fed to a partial oxidation reactor 4 where it reacts (under conditions described more fully below) with oxygen provided as a hot oxygen stream 2 (as described more fully below) to produce additional amounts of hydrogen and carbon monoxide (CO) from the components present in stream 1. If tar is present in the stream, some or all of the tar present may also be converted to lower molecular weight hydrocarbon products.

[0036] The oxidation product stream 13 produced in the partial oxidation reactor 4 is fed to stage 6 where stream 13 is preferably cooled and treated to remove materials that should not be present when the stream is fed to reactor 10 (described below). Stage 6 typically includes a unit to cool stream 13, such as by indirect heat exchange with incoming feed water 61 to produce a heated water and / or steam stream 62. In an alternative embodiment, stage 6 may also include a shift conversion reactor in which the carbon monoxide in stream 13 is reacted in a catalytically mediated water gas shift ("WGS") reaction (in a non-limiting example with water vapor (steam)) to produce hydrogen, thereby providing a means to adjust the ratio of hydrogen to carbon monoxide in stream 13.

[0037] The resulting stream 14, which has been cooled and / or has a hydrogen:CO ratio adjusted in stage 6, is fed to stage 8, where impurities 81 that may be present, such as particles, acid gases including CO2, ammonia, sulfur species, and other inorganic substances such as alkali metal compounds, are removed. Impurities can be removed in one unit or in a series of units, each unit being intended to remove different impurities among these impurities present or to reduce specific pollutants to a desired low level. Stage 8 represents impurity removal, whether it is achieved by one unit or by more than one unit. Cooling and impurity removal are preferably performed in a series of stages or all in one unit in any effective order. Details are not shown, but will be familiar to those skilled in the art. Stage 8 typically includes operations for the final removal of impurities, non-limiting examples of which include particles, NH3, sulfur species, and CO2. CO2 removal is typically performed by a solvent-based process, which uses a physical solvent such as methanol, or a chemical solvent such as amine.

[0038] The resulting cooled, conditioned gaseous stream 15 is then fed to stage 10, which represents any beneficial use of one or more components present in stream 15. That is, stream 15 can be used as a final product as is. However, when stream 15 is to be used as a feedstock to produce Figure 1 The present invention is particularly useful for further reaction and / or other processing of the product designated as 20.

[0039] One preferred example of such further processing is converting stream 15 into a liquid fuel, such as using stream 15 as a feedstock for a Fischer-Tropsch process or other synthesis process to produce liquid hydrocarbons or a mixture of liquid hydrocarbons that can be used as a fuel.

[0040] Other examples of useful processing of stream 15 include the production of specific targeted chemical compounds such as methanol, ethanol, linear or branched or cyclic alkanes and alkanols containing 4 to 18 carbon atoms, aromatic compounds, and mixtures thereof; or in the production of longer chain products such as polymers.

[0041] The overall composition of stream 15 can vary widely depending on the composition of the original feed 1, intermediate processing steps and operating conditions. Stream 15 typically contains (on a dry basis) 20 to 50 volume % hydrogen and 10 to 45 volume % carbon monoxide.

[0042] However, it is preferred that one or more properties of stream 15 will consistently exhibit a value, or values ​​that fall within a characteristic desired range, in order to accommodate the processing that stream 15 undergoes in stage 10 to produce a repeatable, reliable supply of product 20 .

[0043] In the preferred practice of the present invention, the property of stream 15 that is relevant and should be maintained within a desired ratio is the molar ratio of hydrogen (H2) to CO.

[0044] For FT fuel production, the target range for the H2:CO molar ratio depends on the products being produced. For example, methanol production is most efficient with H2:CO in the range of 1.95 to 2.05. Synthetic gasoline production requires an H2:CO ratio in the range of 0.55 to 0.65. For fuel production by other conversion mechanisms (such as bioconversion), the target range for the H2:CO molar ratio can be very large. According to the Wood-Ljungdahl pathway, depending on the type of bacteria used, a stream containing only CO, a stream containing only H2, or a stream containing any combination of H2:CO can be utilized as desired due to the ability of the bacteria to convert H2O and CO2 to H2 and CO. Each bacterial strain will favor a specific chemical composition of the syngas at which it is most efficient in producing the desired product.

[0045] Reference again Figure 1 The processing in stage 10 may produce a byproduct stream 26 which may be recycled to the partial oxidation reactor 4 for use as a reactant and / or recycled to the hot oxygen generator 202 (described below with respect to Figure 2 Description) to be combusted in a hot oxygen generator 202 as described herein. Steam (stream 62) formed from water stream 61 in stage 6 may optionally be fed to the partial oxidation reactor 4.

[0046] refer to Figures 1 to 3 , a hot oxygen stream 2 is fed to a partial oxidation reactor 4 to provide oxygen for the desired partial oxidation of the raw feed 1 and to provide enhanced mixing, accelerated oxidation kinetics, and accelerated kinetics of reforming with the reactor 4.

[0047] There are many ways to provide the required high temperature, high velocity oxygen-containing gas flow, such as plasma heating.

[0048] Figure 2 A preferred way is shown in FIG. 2 , namely a hot oxygen generator 202, which can provide a hot oxygen stream 2 at a high velocity. A stream 203 of a gaseous oxidant having an oxygen concentration of at least 30% by volume and preferably at least 85% by volume is fed into the hot oxygen generator 202, which is preferably a chamber or duct having an inlet 204 for the oxidant 203 and having an outlet nozzle 206 for the hot oxygen stream 2. Most preferably, the oxidant 203 is industrial pure oxygen having an oxygen concentration of at least 99.5% by volume. The oxidant 203 fed to the hot oxygen generator 202 has an initial velocity, which is typically in the range of 50 feet per second (fps) to 300 fps, and will typically be less than 200 fps.

[0049] A stream 205 of fuel is provided to the hot oxygen generator 202 through a suitable fuel conduit 207 terminating in a nozzle 208, which may be any suitable nozzle commonly used for fuel injection. The fuel may be any suitable combustible fluid example, which includes natural gas, methane, propane, hydrogen and coke oven gas, or may be a process stream, such as stream 26 obtained from stage 10. Preferably, the fuel 205 is a gaseous fuel. Liquid fuels, such as No. 2 fuel oil or byproduct stream 23 may also be used.

[0050] The fuel 205 and the oxidant stream 203 in streams should be fed to the generator 202 at rates relative to each other so that the amount of oxygen in the oxidant stream 203 constitutes a sufficient amount of oxygen for the hot oxygen stream for the intended purpose. The fuel 205 provided to the hot oxygen generator 202 is combusted with oxygen from the oxidant stream 203 in the hot oxygen generator to produce heat and combustion reaction products, which may also contain carbon monoxide.

[0051] Combustion within the generator 202 typically raises the temperature of the remaining oxygen within the generator 202 by at least about 500°F, and preferably at least about 1000°F. The hot oxygen obtained in this manner passes from the hot oxygen generator 202 as stream 2 through a suitable opening or nozzle 206 and exits the opening or nozzle as a high velocity hot oxygen stream having a temperature of at least 2000°F and up to 4700°F into the partial oxidation reactor 4. Typically, the velocity of the hot oxygen stream 2 as it exits the nozzle 206 will be in the range of 500 feet per second (fps) to 4500 fps, and will typically exceed the velocity of stream 203 by at least 300 fps. The momentum of the hot oxygen stream and the feed should be high enough to achieve the desired level of mixing of the oxygen with the feed. The momentum flux ratio of the hot oxygen stream to the feed stream should be at least 3.0.

[0052] The composition of the hot oxygen stream depends on the conditions under which it is generated, but preferably it contains at least 50 volume % O2 and more preferably at least 65 volume % O2. The formation of the high velocity hot oxygen stream may be carried out as described in US Pat. No. 5,266,024.

[0053] It will be recognized that the desired state of a system employing partial oxidation in the production of hydrocarbon feedstocks is that there is little or no disturbance in the properties of the original feed 1, the properties of the oxygen stream 2, or the properties of streams 13, 14, and 15, and that there is little or no disturbance in the operating conditions employed in the partial oxidation reactor 4 and in stages 6 and 8.

[0054] However, occasionally situations may arise where the characteristics of the original feed 1 being fed to the POx reactor change such that, without any other changes in operating conditions, the characteristics of stream 15 will be altered in a manner that adversely affects the characteristics of the desired product stream 20. Such changes in stream 20 are, of course, undesirable.

[0055] Examples of such situations include:

[0056] The source 11 of raw feed 1 is unavailable; for example, it is shut down to perform regularly planned maintenance, or to perform necessary repairs due to an unplanned failure or other reason.

[0057] Due to repairs or other operational difficulties with source 11, or because the amount of feed 1 fed to source 11 has been reduced, the amount of raw feed 1 received from source 11 is reduced.

[0058] Because the feed to source 11 has changed, the composition of the original feed 1 has changed.

[0059] The raw feed 1 from the raw feed source 11 becomes too expensive relative to other compositions from other sources that may be useful feed materials for the POx reactor 4 .

[0060] The processing provided in one or more of stages 6 and 8 has been changed, such as a change in the catalytic processing provided in the WGS reaction.

[0061] In the past, the customary operation to accommodate changes such as these involving changes in the characteristics of the raw feed 1 being fed to the POx reactor 4 has generally been to shut down the entire facility or, at best, to operate the facility at a partial load that is detrimental to capital recovery. When this occurs, an operator with more than one such facility must rely on the output of product available from other facilities or suffer a loss of production.

[0062] However, it has been discovered that by utilizing the operational flexibility available from the aforementioned hot oxygen generators, the present invention enables the operator to maintain production of product stream 15 unchanged in the same facility with respect to important compositional characteristics (such as H2:CO molar ratio) and flow rate.

[0063] That is, when the flow of the original feed stream 1 from the source 11 of the original feed to the partial oxidation reactor 4 is interrupted or reduced to any level from less than 100% to greater than 0% of the previous flow rate, an alternative hydrocarbon stream 3 is fed to the partial oxidation reactor 4. The feed rate of the alternative hydrocarbon stream 3 is preferably a rate that supplies a sufficient amount of carbon aggregate input to the POx reactor 4 that is replacing the reduced or interrupted stream 1, preferably sufficient to provide at least the same carbon aggregate input.

[0064] Alternative hydrocarbon feed stream 3 may be produced by source 12 , which refers to a single source that is not source 11 , or more than one single source and none of the single sources is source 11 .

[0065] Suitable alternative hydrocarbon feed streams 3 and sources 12 thereof may be one or more of any of the following:

[0066] natural gas, from any commercial source thereof;

[0067] a gaseous stream produced by a gasification reactor in which solid hydrocarbon material such as biomass or solid fuels such as coal or lignin are gasified in a gas stream, typically comprising air, steam and / or oxygen, at a sufficiently high temperature that at least a portion of the solid material is converted into a gaseous raw stream;

[0068] product and by-product streams, which are more typically gaseous, but can be liquid and / or solid, produced in a petrochemical refinery or chemical plant;

[0069] coke oven gas, which is a waste gas stream produced in a reactor that processes coal to produce coke;

[0070] Pyrolysis gas, a gaseous stream containing hydrocarbons, produced in a reactor to thermally treat solid carbonaceous materials such as fossil fuels or biomass, thereby removing volatile components and partially oxidizing the solid materials;

[0071] Other "optional" feed streams include hydrocarbon oils and liquid hydrocarbons:

[0072] Alternative stream 12 may comprise hydrocarbons containing 1 to 10 carbon atoms and optionally containing one or more oxygen atoms, gaseous and / or liquid, saturated and / or unsaturated and / or cyclic, and mixtures of any such hydrocarbons. Examples include, but are not limited to, natural gas, propane, and liquid fuels. The overall composition of stream 11 will generally be different from the overall composition of the original feed stream 1.

[0073] An alternative hydrocarbon feed stream 12, which may include some of the original feed 1 still being fed from source 11, is partially oxidized in the partial oxidation reactor 4 described herein. The partial oxidation is carried out using a hot oxygen stream 2 generated in a hot oxygen generator 202 described herein. However, the "condition" of the hot oxygen stream 2 fed to the POx reactor 4 in these cases must be adjusted relative to the "condition" of the hot oxygen stream 2 employed when the feed is entirely the original feed 1 and its feeding to the POx reactor 4 before any changes can be accommodated.

[0074] The "conditions" of the hot oxygen gas stream 2 means any one or more of the following:

[0075] The physical characteristics of the hot oxygen stream 2, including its temperature, oxygen content, its feed rate to the POx reactor 4 and the speed at which it is fed to the POx reactor 4, and the conditions (including the stoichiometric ratio) under which the hot oxygen stream 2 is combined and reacted with the alternative hydrocarbon feed stream 3

[0076] The hot oxygen generator 202 is flexible with respect to the properties of the feedstock it can process (such as temperature, composition, and feed rate), and because the hot oxygen generator 202 can be used directly to produce syngas, there is no need to physically change the hot oxygen generator 202 to accommodate changes in any properties of the feed being fed to the partial oxidation reactor 4. Changes in the "conditions" of operation of the hot oxygen generator are implemented to maintain appropriate operating conditions in the partial oxidation reactor 4 using alternative fuels to produce a stream 13 having properties that make the stream 13 suitable for further processing to produce a stream 15 having properties that are unchanged relative to the properties prior to inclusion of stream 3.

[0077] Thus, in the event that the raw feed 1 is to be adjusted or the availability of the raw feed 1 from source 11 is to be switched back or shut down, the operator does not have to completely interrupt the production of the overall plant, but can continue to produce the feed stream 15 (continuing to maintain its desired composition characteristics and other desired characteristics) by adjusting the operating conditions of the hot oxygen generator system together with (if necessary) adjustments of the downstream synthesis gas conditioning and conversion stages.

[0078] It may be added that in embodiments where source 11 employs oxygen in the formation of raw feed stream 1, such as when source 11 is a gasification reactor but operation of source 11 is switched back or shut down, then an amount of oxygen equal to the amount that would have been fed to the gasification reactor (as Figure 1 The material stream 21 in is fed to the partial oxidation reactor 4 to maintain or increase the output of the partial oxidation reactor 4.

[0079] Thus, while adjustments to the conditions of the hot oxygen stream 2 can accommodate changing characteristics of the alternative hydrocarbon feed stream 3 from the original feed 1 (for which the overall plant is designed), it may also be useful to accommodate changing characteristics by adjusting other operations downstream of the partial oxidation reactor 4, such as in the water gas shift reactor (used to maintain the H2:CO molar ratio in stream 15 within a range suitable for producing product 20 in stage 10).

[0080] That is, if the WGS reactor is designed to adjust the gas in stream 13 to a 2.0:1 H2:CO molar ratio in stream 14, then the WGS reactor will be designed to anticipate a particular composition or range of compositions of the syngas in stream 13, such as a H2:CO molar ratio in the range of 0.8:1 to 1.1:1. Then, when an alternative hydrocarbon stream 3 (such as natural gas) is fed to the partial oxidation reactor 4 in place of (or in addition to) the original feed 1, the partial oxidation reactor 4 may (if nothing else changes) produce a stream 13 of a different composition, which may have a H2:CO molar ratio in the range of 1.6 to 1.8. The WGS operation may be adjusted to accommodate changes in the composition of stream 13 as well as adaptations in the partial oxidation reactor.

[0081] Moreover, as described above, changes in the characteristics of the catalyst in the WGS stage may adversely affect the composition of stream 15, again resulting in changes in the overall feed to the POx reactor 4 and appropriate changes in the conditions of the hot oxygen stream 2.

[0082] Providing steam or a CO2-rich gas to the partial oxidation reactor 4 can shift the H2:CO ratio higher or lower, respectively. One variation may require injecting steam or a CO2-rich stream into the POx reactor to adjust the H2:CO ratio. Adding steam shifts some CO to CO2 while producing additional H2 from the added steam. Adding CO2 shifts some H2 to H2O while producing additional CO from CO2. This addition is necessary if the water-gas shift reactor does not have the ability to adjust the H2:CO ratio of the syngas produced using an alternative process, because the ratio is far from the expected H2:CO ratio from biomass-derived syngas. For most applications, this will not be necessary because utilizing alternative feedstocks such as natural gas or propane will produce an H2:CO ratio that is already within the desired range, such as at or near the typical desired ratio of 2.0:1. In some cases, a portion of the gas stream 13 is sent to a WGS reactor that produces a gas with an H2:CO ratio much higher than 2.0:1. This gas is mixed with unshifted gas stream 13A to produce a mixture having a H2:CO ratio of 2.0: 1. If gas stream 13 starts with a ratio closer to 2.0:1 than the designed H2:CO ratio, less gas needs to be processed through the WGS reactor to get 2.0:1.

[0083] Subsequently, when the amount and composition of the original feed 1 from the source 11 becomes fully available again, the flow of the alternative hydrocarbon stream 3 may be interrupted and the full flow of the original feed 1 restored, as in the operation before the original feed 1 was reduced or interrupted. This again changes the characteristics of the feed stream fed to the partial oxidation reactor 4, and thus adjusts the "condition" of the hot oxygen stream 2 relative to the characteristics of the feed 1 that has been changed again, so that the product stream 13 has the desired characteristics. This will generally involve restoring the conditions to those before the feed of the feed 1 was first changed or interrupted. Moreover, the conditioning operations that may be carried out in steps 6 and 8 are adjusted so as to provide a stream 15 with the desired properties and composition suitable for being fed to the stage 10.

[0084] This first aspect of the invention provides several advantages.

[0085] One advantage is that no additional units are required to provide feed to the POx reactor 4 to accommodate switchbacks, shutoffs, or other changes to the original feed 1. The hot oxygen generator already exists in the overall plant for use with the partial oxidation reactor. Because the hot oxygen generator is flexible as to what feedstock to process, it can be utilized in the same plant to produce gas from an alternative feed stream 3. Providing this alternative way to produce the gas stream 15 decouples the POx reactor 4 and stages 6 and 8 downstream of the POx reactor 4 and their associated equipment from dependence on one specific source 11 of feed to be fed to the POx reactor. Utilizing the hot oxygen generator 202 provides the plant with the ability to more fully produce the stream 15 and product 20.

[0086] This advantage, in turn, enables a plant designed to produce a product with a desired set of characteristics (such as a plant producing renewable / biomass-derived liquid fuels) to continuously produce the product at a rate close to or above the rated capacity of the plant. This allows the operator to avoid the alternative of producing nothing, reducing plant uptime and reducing potential plant revenue.

[0087] Example

[0088] These examples assume that biomass-derived syngas is processed in a partial oxidation (POx) reactor started by a hot oxygen generator as described herein under the conditions given in the table. This syngas represents a biomass-derived feedstock and is not specific to any particular configuration. For modeling simplicity, tar and inert materials such as Ar and N2 are not included. The hot oxygen generator is started using pure O2 and natural gas with properties as shown in the table. Assume that the partial oxidation reactor pressure is 50psig.

[0089] Table 1: Raw materials, NG and O2 properties used in the examples .

[0090] Design materials NG Propane O2 temperature °F 1000 70 70 70 H2 volume% 25.0％ H2O volume% 25.0％ CO volume% 15.0％ CO2 volume% 15.0％ 2.0％ CH4 volume% 15.0％ 95.0％ C2H4 volume% 2.5％ C2H6 volume% 2.5％ 3.0％ C3H8 volume% 100％ O2 volume% 100％

[0091] Example 1 :

[0092] Complete replacement of the original synthesis gas produced by gasification of biomass feedstock with an alternative hydrocarbon feed stream

[0093] Five scenarios are given:

[0094] 1. Design - Planned operation using biomass derived syngas feedstock and O2 supplied by a hot oxygen generator

[0095] 2. Natural gas as an alternative feed - replacing biomass-derived syngas with natural gas while maintaining the design O2 feed rate

[0096] 3. Natural Gas as Alternative Feed + 20% Additional O2 - Replace the biomass derived syngas with natural gas and increase the feed rate of O2 fed to the partial oxidation reactor (from the hot oxygen generator) by 20%

[0097] 4. Natural gas + CO2 as an alternative feed - Replace the biomass derived syngas with a mixture of natural gas and CO2 to adjust the H2:CO ratio while maintaining the design O2 feed rate

[0098] 5. Propane as feed - Replace biomass-derived syngas with propane while maintaining the design O2 feed rate

[0099] Scenario 2 and Scenario 5 show how the performance of a hot oxygen generator system, whose operating parameters are designed for partial oxidation of biomass-derived syngas, varies when applied to different feedstocks. This would correspond to an embodiment in which the flow of the original syngas stream from the gasification reactor is completely interrupted and natural gas or propane is instead fed to the POx reactor as an alternative hydrocarbon feed. Scenario 2 and Scenario 3 show the additional O2 available to the POx reactor (at Figure 1 Scenario 2 and Scenario 4 show how CO2 (in Figure 1 How the H2:CO ratio can be adjusted by the addition of (appearing as feed stream 16).

[0100] The results of these simulations are given in the table. Scenario 2 and Scenario 5 show a 17% and 13% reduction in H2+CO, respectively. While the reduction in H2+CO is not ideal, keeping production at any level above zero is a large improvement and is preferred to stopping production of downstream products. Scenario 3 shows that increasing the O2 rate fed to the POx reactor (possibly by releasing the O2 being used by the gasifier) ​​can restore the production of H2+CO to the design level. Increasing the O2 rate further makes it possible to exceed the design production of H2+CO.

[0101] For Scenario 2 and Scenario 5, the H2:CO molar ratios are 1.7 and 1.3, also different from the expected design value of 1.2 in this example. The H2:CO ratio typically varies depending on the product being produced downstream (see the water-gas shift (WGS) reaction). For example, methanol production may require an H2:CO ratio close to 2.0, while synthetic gasoline may require a ratio close to 0.6. A typical plant configuration is to split the synthesis gas stream after the POx reactor, sending some to the WGS reactor and allowing some to bypass the reactor ( Figure 113A in FIG. 13A). The amount of shift in this reactor causes the H2:CO ratio of that portion of the syngas to exceed the necessary range so that the desired H2:CO ratio is achieved when the two streams are blended together again. Referring to Scenario 2, if the plant requires an H2:CO ratio of 2.0, it is desirable to start with an H2:CO ratio of 1.7 (because it reduces the amount of shift required), thereby allowing the plant to reduce the amount of syngas required to pass through the shift reactor and extend catalyst life, or increase production by using the same size WGS reactor to process more of the total syngas.

[0102] However, if the plant requires a H2:CO ratio of 0.6, an increase in the H2:CO ratio from 1.2 to 1.7 may not be acceptable. Scenario 5 shows that a different alternative hydrocarbon stream can be used to produce an H2:CO ratio similar to the design syngas. Scenario 4 shows that adjustments to the H2:CO ratio can also be made by adding CO2 to the natural gas being fed to the POx reactor. Adding CO2 causes the H2:CO ratio to decrease; adding enough CO2 can restore the H2:CO ratio to the design value. Similarly, the H2:CO ratio can be increased, if desired, by adding H2O to the feed stream being fed to the POx reactor.

[0103] The thermal oxygen generator can easily handle all of these operating scenarios without interruption and without the need for hardware or control changes.

[0104] Table 2: Predictions for the full replacement scenario

[0105]

[0106] Example 2 :

[0107] Partial replacement of the original synthesis gas produced by gasification of biomass feedstock with an alternative hydrocarbon feed stream

[0108] Example 2 shows operation where the gasification reactor still provides syngas to the partial oxidation reactor but at a reduced flow rate relative to full operation. Utilization of a hot oxygen generator with a POx system enables the operator to maintain syngas production at the design rate or increase syngas production by allowing an alternative hydrocarbon feed stream to be fed to the POx reactor in addition to the reduced syngas.

[0109] The table gives the results of comparing the design conditions with the following situation: the synthesis gas at a rate of 50% is supplemented with natural gas used as an alternative hydrocarbon feed at an increasing flow rate. Increasing the natural gas flow rate requires an increase in the amount of O2 fed to the POx reactor and results in an increase in the amount of H2+CO produced. If the O2 feed rate fed to the POx reactor is maintained at the design level, the H2+CO rate leaving the POx reactor is only slightly lower than the design. If an additional amount of O2 is fed to the POx reactor, which is available due to the low O2 utilization in the gasification reactor, the production of fuel can be increased to exceed the design level. If additional production of fuel is desired, it is feasible to feed the POx reactor with an alternative hydrocarbon feed even if the synthesis gas flow rate fed to the POx reactor is at the design rate. This may be limited by the amount of O2 available for the plant or the size of downstream equipment such as the WGS reactor, other synthesis gas conditioning equipment (syngas cooler, CO2 removal, other finishing reactors), or the conversion step itself.

[0110] As in Example 1, the H2:CO molar ratio for the partial replacement scenario is different from the design. These differences can be handled in a similar manner to that explained above.

[0111] Table 3: Predictions for partial replacement scenarios .

[0112]

[0113] Supply steam to the POX reactor during commissioning (startup) or restart of the feed source

[0114] Another embodiment that can take advantage of the present invention occurs in a plant designed so that the source 11 that provides the raw material 1 to the POx reactor utilizes steam in the production of the raw feed 1. This embodiment can be employed when such a plant is first brought online or in certain scenarios where a source 11 that utilizes steam is used to provide the raw feed 1 to the POx reactor 4, then the source is shut down and then restarted again to resume providing the raw feed 1 to the POx reactor 4.

[0115] These aspects of the invention take advantage of the fact that the POx system is so flexible that a separate auxiliary steam boiler is not necessary to provide steam for the startup (or restart) reactor (which employs steam in the generation or production of the original feed for the POx reactor), or if used, can simply be reduced in size. An example of such a reactor is a gasification reactor. In conventional practice to date, a startup boiler is required to provide steam to the gasification reactor during startup. As described herein, using the hot oxygen generator of the present invention with the POx reactor, it is possible to generate steam from water-based cooling (in Figure 1This steam can then be used to start up the gasification reactor. Bringing a solid feedstock gasifier online and operational is one of the major time consuming steps during plant commissioning.

[0116] By means of the present invention, the system described herein including a hot oxygen generator may be used with alternative feedstocks to reduce commissioning time by providing feed to downstream equipment at full or partial load from a source other than the source that employs steam in its operation, thereby allowing the other equipment to be commissioned independently of the gasifier.

[0117] These features and advantages are demonstrated in Example 3 below.

[0118] Example 3

[0119] The use of a hot oxygen generator with a POx reactor can reduce commissioning time. An integrated plant for producing hydrocarbon feedstocks as described herein may have several unit operations downstream of the stage for producing the raw feed 1. As shown herein, such stages may include compression, WGS, removal of impurities, and conversion. In the startup of the overall plant, these unit operations must be debugged using the gases that would normally be used in full operation. If a gasification reactor or other reactor using steam as a reagent or gas production agent is to be used as a source of the raw feed 1 to be processed and converted in the plant, if the reactor using steam has any operating problems, the commissioning of the plant as a whole will be delayed. As another beneficial effect, as described herein, a hot oxygen generator system can be used to provide a reliable alternative feed 3 for debugging equipment downstream of the reactor.

[0120] For example, a fully commissioned biomass gasifier may be fully functional no more than 85% of the time. The reliability of this type of gasifier will obviously be much lower and create an unreliable gas source for commissioning of the POx reactor 4 and equipment downstream of the reactor 4. The scenario presented in Example 1 shows that a hot oxygen generator system can be used to provide a gas stream with properties similar to the gas stream that the plant is designed to produce, thereby allowing the balance of the plant to be commissioned with a reliable gas source fed to the POx reactor.

[0121] There are a variety of ways in which a hot oxygen generator can be implemented to take advantage of this capability.

[0122] One embodiment is to inject steam or a CO2-rich stream into the POx reactor to adjust the H2:CO ratio of the stream produced in the POx reactor. Adding steam converts some of the CO to CO2 while producing additional H2 from the added steam. Adding CO2 converts some of the H2 to H2O while producing additional CO from the CO2. This addition would be necessary if the water-gas shift reactor did not have the ability to adjust the H2:CO ratio of the syngas produced using an alternative process because the ratio would be far from the expected H2:CO ratio from biomass-derived syngas. For most applications, this would not be necessary because utilizing alternative feedstocks such as natural gas or propane would produce an H2:CO ratio that is closer to the typical desired ratio of 2.0:1. Typically, only a portion of the syngas is sent to the WGS reactor, which produces a gas with a H2:CO molar ratio much higher than 2.0:1. This gas is mixed with the unshifted syngas (in Figure 1 The syngas is mixed with the by-pass stream 13A in FIG. 1 to produce a mixture having a H2:CO molar ratio of 2.0:1. If the syngas starts with a H2:CO molar ratio closer to 2.0:1 than the design syngas, less syngas needs to be processed through the WGS reactor to obtain a 2.0:1 molar ratio.

Claims

1. A method for producing a hydrocarbon feedstock, the method comprising: (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed optionally contains tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen such that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed while converting tar, if present in the raw feed, to lower molecular weight products comprising hydrogen and CO, thereby producing a hydrocarbon feedstock having a molar ratio of hydrogen to CO at a first value; (B) replacing the original feed fed to the partial oxidation reactor with a regulated feed fed to the partial oxidation reactor, and the replacement is made by: (i) reducing or interrupting the amount of the original feed fed to the partial oxidation reactor from a source of the original feed; and (ii) feeding a hydrocarbon feed stream to the partial oxidation reactor that is not from the source of the original feed and that has a composition different from the composition of the original feed, and continuing to feed an oxygen stream having a temperature of 2000F to 4700F into the partial oxidation reactor, wherein reaction of the conditioned feed with the oxygen in the partial oxidation reactor under the conditions under which the original feed reacted with oxygen in step (A) produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a second value different from the first value, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor such that its reaction with the conditioned feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a third value different from the second value; and then (C) completely replacing the adjusted feed fed in step (B) with all of the original feed from the source fed to the partial oxidation reactor, while continuing to feed an oxygen stream having a temperature of 2000F to 4700F to the partial oxidation reactor, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor relative to the conditions employed in step (B) so that its reaction with the original feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is different from the third value.

2. A method for producing a hydrocarbon feedstock, the method comprising: (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed optionally contains tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen such that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed while converting tar, if present in the raw feed, into lower molecular weight products comprising hydrogen and CO, and recovering an intermediate feed stream from the partial oxidation reactor; (B) catalytically adjusting the molar ratio of hydrogen to CO in the intermediate feed stream from step (A) to produce a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at a first value; (C) replacing the original feed fed to the partial oxidation reactor with a regulated feed fed to the partial oxidation reactor, and the replacement is made by: (i) reducing or interrupting the amount of the original feed fed to the partial oxidation reactor from a source of the original feed; and (ii) feeding a hydrocarbon feed stream to the partial oxidation reactor that is not from the source of the original feed and that has a composition different from the composition of the original feed, and continuing to feed an oxygen stream having a temperature of 2000F to 4700F to the partial oxidation reactor, wherein reaction of the conditioned feed with the oxygen in the partial oxidation reactor under the conditions under which the original feed reacted with oxygen in step (A) and subsequent catalytic conditioning under the conditions employed in step (B) produces a hydrocarbon product in which the molar ratio of hydrogen to CO is at a second value, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor such that its reaction with the conditioned feed and subsequent catalytic conditioning produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is at the second value; and then (D) completely replacing the adjusted feed fed in step (C) with all of the original feed from the source fed to the partial oxidation reactor, while continuing to feed an oxygen stream having a temperature of 2000F to 4700F to the partial oxidation reactor, and changing at least one condition of the oxygen stream fed to the partial oxidation reactor relative to the conditions employed in step (C) such that its reaction with the original feed and subsequent catalytic adjustment produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is different from the second value.

3. A method for producing a hydrocarbon feedstock, the method comprising: (A) feeding both (i) a raw feed from a source of raw feed and (ii) an oxygen stream having a temperature of 2000F to 4700F into a partial oxidation reactor, wherein the raw feed optionally contains tar and comprises hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof, and reacting the raw feed with the oxygen so that one or more of the light hydrocarbons in the raw feed are partially oxidized by the oxygen to increase the amount of hydrogen and CO in the raw feed, while converting the tar, if present in the raw feed, to lower molecular weight products comprising hydrogen and CO, and recovering an intermediate feed stream from the partial oxidation reactor in which the molar ratio of hydrogen to CO is within a given range; (B) generating steam by heating liquid water in indirect heat exchange with said intermediate feed stream produced in step (A); (C) feeding the steam and the carbonaceous feed material produced in step (B) to a reactor to produce a second raw feed by interaction of the steam with the carbonaceous feed material, the second raw feed optionally containing tar and comprising hydrogen and CO and one or more light hydrocarbons selected from the group consisting of methane, hydrocarbons containing 2 or 3 carbon atoms, and mixtures thereof; and (D) replacing the original feed fed in step (A) with the second original feed fed to the partial oxidation reactor, while continuing to feed an oxygen flow having a temperature of 2000F to 4700F into the partial oxidation reactor so that its reaction with the second original feed produces a hydrocarbon feedstock in which the molar ratio of hydrogen to CO is within the given range.

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