CN117545809A

CN117545809A - Method and apparatus for recovery and reuse of tail gas and flue gas components

Info

Publication number: CN117545809A
Application number: CN202280045177.6A
Authority: CN
Inventors: 王大祥; W-M·迟; D·S·克罗克; M·C·格林; D·M·马修; R·戴维斯
Original assignee: Cabot Corp
Current assignee: Cabot Corp
Priority date: 2021-06-24
Filing date: 2022-06-23
Publication date: 2024-02-09

Abstract

A process for producing carbon black includes converting a portion of at least one hydrocarbon feedstock to carbon black in the presence of combustion gases generated by combusting a fuel in an oxidizing gas mixture containing a low amount of nitrogen in a carbon black reactor having a combustion zone and a reaction zone and an intervening feedstock injection zone to form a product stream in which carbon black is carried by hot gases. The carbon black is separated from hot gases, which are then treated to produce high carbon dioxide and low nitrogen flue gas, at least a portion of which is redirected to at least one of the combustion zone, the reaction zone, and the feedstock injection zone.

Description

Method and apparatus for recovery and reuse of tail gas and flue gas components

Technical Field

The present invention relates to a method and apparatus for recovering and reusing components of tail gas and flue gas produced during carbon black production and tail gas combustion.

Background

Carbonaceous fuels and other organic materials are combusted in a wide variety of industrial processes. Furnace reactors, internal combustion engines, combustion chambers, boilers, furnaces, heaters, hot gas generators, burners, waste incinerators, and the like are used to combust carbonaceous fuels. Such combustion apparatus may be used to make energy, incinerate waste and byproduct materials, or both. For example, during a typical combustion process within a furnace or boiler, a hydrocarbon feedstock or fuel is combusted in the presence of oxygen or other oxidizing gas and a stream of combustion exhaust gases is produced. In certain industries, such as in carbon black production, refinery operations, or petrochemical operations, the exhaust gas generated in the primary process unit is sent to a heater or boiler for energy production or heat recovery. These operations may generate emissions that may be subject to any applicable air quality control or requirements.

For example, furnace carbon black production processes typically employ a furnace reactor having a burner or combustion chamber followed by a reactor. A combustion fuel feed stream (stream) (typically a hydrocarbon gas stream, such as natural gas, etc.) is combusted in a burner section along with an oxidant feed gas stream, such as air, oxygen, or oxygen-enriched air, to produce hot combustion gases, which are then passed to a reactor section of a furnace. In the reactor, the hydrocarbon feedstock is exposed to hot combustion gases. The feedstock is partially combusted, while the remainder is decomposed to form carbon black, hydrogen, carbon monoxide and other gaseous products. The reaction product is typically quenched with water and the resulting product stream (i.e., a mixture of carbon black and tail gas) is cooled and sent to a bag collector or other filtration system whereupon the carbon black content is separated from the tail gas. The recovered carbon black is typically finished (finish) as a marketable product, such as, for example, by grinding and wet granulation. The water from the granulation is typically driven off using a dryer, which may be gas, fuel, combustion process gas (e.g., with off-gas), or a combination of these. The dried pellets may then be transported from the dryer to bulk storage or other processing. The dryer may also generate gaseous emissions. The primary source of emissions in the carbon black furnace process is typically from the tail gas. Unlike direct venting, tail gas emissions have been vented using a flare. The tail gas may contain combustible gas components. The tail gas may be advantageously combusted to generate heat for a dryer as described above or for other uses. After combustion, the resulting flue gas typically may include carbon dioxide, water, nitrogen, oxygen, and other species. Carbon dioxide may be separated from the flue gas and sequestered to reduce greenhouse gas emissions. However, it is desirable to more effectively use the various gas species present in the tail gas and flue gas. Furthermore, it is desirable to increase the concentration of carbon dioxide in the flue gas to improve the efficiency of the greenhouse gas separation process prior to any emission of the flue gas.

Disclosure of Invention

In one aspect, a method for producing carbon black includes converting a hydrocarbon feedstock to carbon black in one or more reaction zones in the presence of a combustion gas generated in a combustion zone by combusting the fuel in an oxidizing gas mixture comprising 20-85% by volume carbon dioxide, 15-80% by volume oxygen, up to 30% by volume water, and up to 35% by volume nitrogen in a carbon black reactor comprising the combustion zone, at least one feedstock injection zone downstream of the combustion zone, and at least one reaction zone downstream of the first feedstock injection zone, to form a first product stream comprising carbon black, carbon dioxide, carbon monoxide, water vapor, and hydrogen, wherein the fuel is part of the hydrocarbon feedstock or a separate fuel source, and wherein at least part of the hydrocarbon feedstock is contacted with the combustion gas in the at least one feedstock injection zone. The process further includes adding water to the first product stream to at least partially stop the conversion and form a second product stream comprising carbon black, carbon dioxide, carbon monoxide, hydrogen, and water vapor; removing carbon black from the second product stream to form an off-gas; reducing the carbon monoxide and hydrogen content in at least a portion of the tail gas to produce a flue gas, reducing the carbon monoxide and hydrogen content in at least a portion of the tail gas to produce a flue gas comprising up to 40% by volume nitrogen; and directing at least a first portion of the flue gas to at least one of a combustion zone, at least one feedstock injection zone, and at least one reaction zone.

The first product stream can further include sulfur-containing species, and removing water can further include removing at least a portion of the sulfur-containing species from the first portion of the flue gas, the second portion of the flue gas, or both. The reducing may include combusting the tail gas, separating and recovering at least a portion of the hydrogen from the tail gas, or both. The first product stream and the second product stream may each contain carbon monoxide and the reducing may further comprise combusting the tail gas after separation and recovery. The method may further comprise removing water from the tail gas prior to removing hydrogen. The method may further include directing at least a portion of the tail gas to a combustion zone. The method may further comprise removing water from the exhaust gas prior to directing at least a portion of the exhaust gas, and the removed water may be directed for use in step (b).

The method may further include combining the first portion of the flue gas with an oxidizing reactant prior to directing, wherein the oxidizing gas mixture comprises the combined first portion of the flue gas and the oxidizing reactant, and the combined first portion of the flue gas and the oxidizing reactant may be directed to a combustion zone, a reaction zone, or both. The method may also include heating the first portion of the flue gas prior to combining. The method may also include heating the first portion of the combined flue gas and the oxidizing reactant. The method may also include heating the first portion of the flue gas prior to directing. The method may further include combining the first portion of the flue gas with the hydrocarbon feedstock prior to directing, wherein the combined flue gas and hydrocarbon feedstock are directed to at least one feedstock injection zone. The method may also include heating the first portion of the combined flue gas and the hydrocarbon feedstock. The method may also include heating a first portion of the flue gas to form a hot flue gas and combining the hot flue gas with the hydrocarbon feedstock prior to directing. The method may further include heating the first portion of the flue gas with an energy source selected from the group consisting of microwaves, plasmas, and resistive heating elements.

The method may further include removing water from the first portion of the flue gas to produce dehydrated flue gas comprising up to 35% by volume of water, and the removed water may be directed for use in step (b). The method may further comprise granulating at least a portion of the carbon black by: combining the portion with a liquid to form carbon black beads, and drying the carbon black beads to reduce the water content to at most 1 wt%, wherein drying comprises heating the dehydrated flue gas and contacting the carbon black beads with the heated dehydrated flue gas. The method may further include diverting a portion of the dehydrated flue gas and removing at least a portion of the carbon dioxide from the diverted dehydrated flue gas. The method may further include either or both condensing and storing carbon dioxide removed from the diverted dehydrated flue gas.

In the case of flue gas dehydration, the method may further comprise providing an oxidizing gas by allowing liquid oxygen to evaporate, wherein the method further comprises transferring thermal energy from the dehydrated flue gas to the liquid oxygen. Removing soot may include passing the second product stream through a filter that separates the second product stream into soot and tail gas, wherein the method further includes purging (purge) solid particulates from the filter with dehydrated flue gas. Removing the carbon black may include passing the second product stream through a cyclone, and the method may further include separating off-gas and carbon black in the cyclone with a portion of the dehydrated flue gas. The method can further include compressing at least a portion of the dehydrated flue gas, and removing carbon black can further include passing the second product stream through a filter, and optionally using the compressed dehydrated flue gas to clean the filter. The reducing may include combusting tail gas in a combustor, and the method may further include using the compressed dehydrated flue gas to clean the combustor.

Adding water may also include adding at least a portion of the first portion of the flue gas to the first product stream to stop the conversion.

In another aspect, the carbon black is formed using any combination or sub-combination of the method steps outlined above.

In another aspect, an apparatus for producing carbon black comprises: a carbon black reactor, the carbon black reactor comprising: a combustion zone for combusting an oxidizing gas mixture and a fuel to produce a heated gas stream; a first feedstock injection zone for injecting a hydrocarbon feedstock into the heated gas stream to form a product stream; a first reaction zone within which carbon black is formed in the product stream; a first quench ejector; and a first quench zone within which the carbon black is at least partially quenched with a quench fluid injected into the product stream from the first quench injector. The apparatus further includes a separator in fluid communication with the first quench zone, wherein carbon black is separated from the product stream to form a tail gas; a thermal oxidizer configured to combust the tail gas with additional oxidizing gas to form a hot flue gas; and a first flue gas heat exchanger that removes thermal energy from the hot flue gas to form cooled flue gas. The outlet is in fluid communication with and upstream of at least one of the combustion zone, the first feedstock injection zone, and the first reaction zone.

The apparatus may also include a scrubber cooler including a sulfur species scrubber and a water condenser. The scrubber cooler is for removing sulfur-containing species and water from at least a portion of the cooled flue gas, thereby producing dehydrated flue gas, and includes an outlet through which the dehydrated flue gas is discharged. The outlet of the scrubber cooler may also be in fluid communication with a heater. The apparatus may also include a carbon black pelletizer configured to receive at least a portion of the heated dehydrated flue gas, which then dries the carbon black pellets formed in the pelletizer. The separator may comprise a bag filter and the apparatus is operable to direct at least a portion of the dehydrated flue gas to periodically purge particulate solids from the bag filter. The apparatus may further include a carbon capture system operable to remove at least a portion of the carbon dioxide present in the dehydrated flue gas.

The heat exchanger may be a boiler, wherein heat energy from the hot flue gas is transferred to the water. The apparatus may also include a compressor configured to receive the flue gas from the outlet and discharge the compressed flue gas. The apparatus may be configured to direct at least a portion of the tail gas to the combustion zone. The apparatus may also include a condenser upstream of the combustion zone configured to remove water from the tail gas. The apparatus may also include a hydrogen removal device upstream of the combustion zone configured to remove hydrogen from the tail gas. The apparatus may further include a second quench injector and a second quench zone wherein at least a portion of the quenched carbon black is further quenched with a quench fluid injected into the product stream from the second quench injector.

The apparatus may further include a heater disposed between the outlet and at least one of the combustion zone and the first reaction zone to heat at least a portion of the flue gas. The heater includes a microwave source, a plasma source, or a resistive heating element. The apparatus may further comprise a heat exchanger receiving the product stream from the first quench zone, wherein the heat exchanger is operable to exchange heat of the product stream with at least a portion of the flue gas to heat said portion of the flue gas to a temperature of 400 to 950 ℃.

The apparatus may be configured to combine at least a portion of the flue gas with additional oxidizing gas and direct the combined flue gas and additional oxidizing gas to the thermal oxidizer. The combustion zone, the first reaction zone, or both may be configured to receive an oxidizing gas mixture, which in turn comprises a mixture of cooling flue gas and a portion of the mass of oxidizing reactant. That is, a portion of the cooled flue gas may be further treated, for example, by removing sulfur and/or sulfur-containing species, removing water vapor, heating, compressing, or more than one of these, and the treated portion of the cooled flue gas is then combined with the oxidation reactant.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention as claimed.

Drawings

The present invention is described with reference to several figures of the drawings, in which

Fig. 1 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 2 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 3 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

FIG. 4 is a schematic diagram illustrating an exemplary method of converting tail gas from a carbon black manufacturing process into dehydrated flue gas according to an exemplary embodiment.

Fig. 5 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 6 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 7 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 8 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to various exemplary embodiments.

Fig. 9 is a schematic diagram showing the operation of the carbon black production process according to the comparative example.

Fig. 10 is a schematic diagram illustrating the operation of a carbon black manufacturing process according to an exemplary embodiment.

Detailed Description

In one embodiment, a method for producing carbon black comprises: at least one raw material injection zone downstream of the combustion zone having a combustion zone, and a first raw materialIn a carbon black reactor injected into at least one reaction zone downstream of the zone, a hydrocarbon feedstock is converted to carbon black in one or more reaction zones in the presence of combustion gases generated in the combustion zone by combusting the fuel in an oxidizing gas mixture comprising 20-85% by volume carbon dioxide, 15-80% by volume oxygen, up to 30% by volume water, and up to 35% by volume nitrogen to form a first product stream comprising carbon black, carbon dioxide, carbon monoxide, hydrogen, and water vapor, wherein the fuel is part of the hydrocarbon feedstock or a separate fuel source, such as burner fuel 24. Water is added to the first product stream to substantially stop conversion and form a second product stream comprising carbon black, carbon dioxide, carbon monoxide, hydrogen and water vapor. Carbon black is removed from the second product stream to form a tail gas that is treated to oxidize and optionally remove oxidizable species such as carbon monoxide and hydrogen to produce a flue gas comprising up to 40% by volume nitrogen, and at least a portion of the flue gas is directed to at least one of the combustion zone, the at least one feedstock injection zone, and the at least one reaction zone. The flue gas may optionally be treated to reduce SO _x 、NO _x And the concentration of water vapor to produce dehydrated flue gas.

The various embodiments and methods and apparatus of the embodiments may be used to retrofit any furnace carbon black reactor known to those skilled in the art. For example, these methods and apparatus can be used to retrofit furnace carbon black reactors, such as U.S. Pat. No.3,922,335;4,383,973;5,190,739;5,877,250;5,904,762;6,153,684;6,156,837;6,403,695;6,485,693;7,829,057;8,871,173; and 10,829,642, all of which are incorporated by reference in their entirety. In the exemplary embodiment shown in FIG. 1, carbon black is produced in a furnace carbon black reactor 10 comprising a combustion zone 12, a feedstock injection zone 14, a reaction zone 16, and a first quench zone 18 after a first injector 20 for process water 22. The process water 22 may be pumped through the first injector 20 and any subsequent injectors, or may be injected through one or more injectors via a venturi mixer. To produce carbon black, hot combustion gases are generated in combustion zone 12 by reacting liquid or gaseous burner fuel 24 with a suitable oxidizing gas mixture comprising an oxidizing reactant 26 and other gases described below. At least some of the components of the oxidizing gas mixture enter the combustion zone 12 via a first oxidizing gas inlet 27, and the combustor fuel 24 enters the combustion zone 12 via a fuel inlet 25. The hot combustion gas stream flows downstream from the combustion zone 12 through the feedstock injection zone 14.

The carbon black yielding feedstock may be introduced into the feedstock injection zone 14 radially, axially, or both. The carbon black yielding feedstock is typically heated prior to introduction. As shown in fig. 1, the carbon black yielding feedstock 28 is heated in a feedstock heater 70 to form a heated feedstock 31. The radially injected heated feedstock 31 may be injected from a plurality of feedstock inlets disposed about the periphery of the feedstock injection zone 14 and injected in a transverse orientation into the hot combustion gas stream traveling from the combustion zone 12 to the reaction zone 16. Upon introduction, the heated feedstock 31 is mixed with the hot combustion gas stream to form a product stream, wherein the carbon black-producing feedstock is pyrolyzed and carbon black is formed in the reaction zone 16.

Optionally, and as shown in fig. 1, an additional oxidizing gas mixture comprising an oxidizing reactant 26 is supplied as a secondary oxidizing stream to the reaction zone 16 via a secondary oxidizing gas inlet 29. The carbon black in the product stream may be quenched in one or more quench zones (e.g., first quench zone 18), each of which is supplied by one or more injectors (e.g., first injector 20). The available diameters and lengths of the various zones and the amount of water injected by the various injectors may be selected with reference to the patents identified above, which are incorporated by reference. Those skilled in the art will fully understand the effect of these parameters on the final morphology of the carbon black and will not alter the operation of the various embodiments herein. Alternative carbon black reactor configurations are also possible, such as configurations employing two or more reaction zones, optionally separated by a quench zone, in which the reaction is partially quenched and additional carbon black-yielding feedstock is injected in each subsequent reaction zone (FIG. 1A). Alternatively or additionally, additional feedstock 28 or heated feedstock 31 can be injected into reaction zone 16 without first quenching the reaction with process water 22 (FIG. 1B).

Fuels suitable for use in reacting with the oxidizing gas mixture in combustion zone 12 to produce a hot combustion gas stream include any readily combustible gas, vapor, and/or liquid stream, such as natural gas, coal gas, biomass liquid, liquid fuel produced from chemical process byproduct streams, hydrogen, carbon monoxide, methane, acetylene, alcohols, kerosene, or any fuel gas having a fuel gas composition of greater than 2MJ/Nm ³ Low Heating Value (LHV) gas. Combinations of these may also be employed. However, it is generally preferred to utilize fuels, and particularly hydrocarbons, having a high content of carbonaceous components. For example, any of the carbon black yielding feedstock listed below may also be used as the burner fuel 24. The combustor fuel 24 may be injected into the combustion zone 12 at any temperature from its ambient temperature (i.e., without any heating or cooling) to 800 ℃. To facilitate the generation of hot combustion gases, the oxidizing reactant 26, the oxidizing gas mixture comprising the oxidizing reactant 26, or other components of the oxidizing gas mixture may be preheated to a temperature of, for example, 400-950 ℃ before or after mixing. For example, in fig. 3, the oxidizing reactant 26 is heated in a heat exchanger 85.

The carbon black yielding feedstock useful in the present invention may include any hydrocarbon gas, liquid or oil feedstock useful in the production of carbon black. Suitable liquid feedstocks include, for example, unsaturated hydrocarbons, saturated hydrocarbons, olefins, aromatics, and other hydrocarbons such as biomass-derived liquids, decant oils (decant oils), coal tar-derived liquids, asphaltene-containing oils, kerosene, naphthalene, terpenes, ethylene tar, pyrolysis resid, oils produced from recycled materials, or any combination thereof. In general, any hydrocarbon-containing liquid having a carbon content of at least 60 wt.% may be employed. Suitable gaseous feedstocks include, for example, natural gas, methane, ethylene, acetylene, and other C4-C6 hydrocarbon gases. Any of these feedstocks may be treated using techniques known to those skilled in the art to remove sulfur or other undesirable species prior to use. The carbon black-yielding feedstock 28 may be injected into the feedstock injection zone 14 or a subsequent injection zone as discussed above at any temperature from its ambient temperature (i.e., without any heating or cooling) to 500 ℃ (for liquid feedstock) or to 900 ℃ (for gaseous feedstock).

Moreover, any of the raw materials used in the process schemes and methods may contain additional materials or compositions commonly used in the manufacture of conventional carbon blacks. The method of the present invention may further comprise introducing at least one substance that is or contains at least one group IA and/or group IIA element (or ion thereof) of the periodic table of elements. The substance containing at least one group IA and/or group IIA element (or ion thereof) contains at least one alkali metal or alkaline earth metal. Examples include lithium, sodium, potassium, rubidium, cesium, francium, calcium, barium, strontium, or radium, or combinations thereof. Any mixture of one or more of these components may be present in the substance. The substance may be a solid, a solution, a dispersion, a gas, or any combination thereof. More than one species having the same or different group IA and/or group IIA metals (or ions thereof) may be used. If multiple species are used, these may be added together, separately, sequentially, or in different reaction sites. For the purposes of the present invention, the substance may be the metal (or metal ion) itself, a compound containing one or more of these elements, including salts containing one or more of these elements, and the like. The material is capable of introducing a metal or metal ion into an ongoing reaction to form a carbon black product. For the purposes of the present invention, if used, the material containing at least one group IA and/or IIA metal (or ion thereof) may be introduced at any point in the reactor, for example prior to complete quenching. If used, the amount of group IA and/or group IIA metal (or ion thereof) containing material can be any amount so long as a carbon black product can be formed. The substance may be added in the same manner as the carbon black-yielding feedstock is introduced. The substance may be added as a gas, liquid, or solid, or any combination thereof. The substance may be added at one point or several points and may be added as a single stream or as multiple streams. The materials may be mixed with the feedstock, fuel, and/or oxidant prior to or during their introduction.

In addition to carbon black, the product stream contains carbon dioxide, carbon monoxide, hydrogen and water vapor. Before quenchingWater vapor is present and the product stream becomes more humid due to quenching. In addition, the product stream may include some nitrogen, acetylene, SO _x 、NO _x And other species typically generated during the furnace carbon black production process. After quenching, the product stream containing the hot carbon black may pass through one or more heat exchangers, such as through heat exchanger 30. The use of the heat thus extracted is discussed in more detail below. As shown in fig. 1, heat exchanger 30 transfers heat from the product stream to the gas, but heat exchanger 30 and any subsequent heat exchangers may also be boilers or other heat exchangers that transfer heat from the hot product stream to the liquid. The cooling zone 32, which is supplied with process water 22 by cooling zone injectors 34, may provide additional opportunities to control the temperature of the product stream after it passes through one or more heat exchangers, prior to any separation and cooling steps described below. Alternatively or additionally, a similar cooling zone may precede a particular heat exchanger to control the temperature of the product stream entering the heat exchanger.

After the product stream is quenched, it is passed downstream to any conventional separation and cooling steps, whereby carbon black is recovered (represented in fig. 1 as separator 36). Separator 36 may include devices such as bag filters, ceramic filters, cyclones, other devices known to those skilled in the art for separating particles from a gas stream, or a combination of two or more of these. Separation of the quench product streams results in two product streams: carbon black 37 and tail gas 38. Those skilled in the art will recognize that small amounts of tail gas may be present in the stream of carbon black 37 and vice versa.

Carbon black 37 can be any conventional carbon black. For example, carbon black 37 can be any N-series carbon black according to ASTM D-1765, such as N100, N200, N300, N500, N600, N700, N800, or N900 series carbon black. More specific examples of ASTM N-series carbon blacks include N110, N121, N134, N220, N231, N234, N299, N326, N330, N339, N347, N351, N358, N375, N550, N660, N683, N762, N765, N774, or N990 carbon blacks. Alternatively or additionally, carbon blacks produced according to embodiments provided herein may have, for example, from 30 to 450mL/100g of carbon black, e.g. 30 to 100mL/100g, 100mL/100g to 200mL/100g, 200mL/100g to 300mL/100g, or 300mL/100g to 450mL/100g of oil absorption (OAN, ASTM D-6556). Alternatively or additionally, and in combination with any of the structural values provided above, the carbon black may have a molecular weight of 5 to 1800m ² /g, e.g. 8m ² /g to 150m ² /g、150m ² /g to 350m ² /g、350m ² /g to 600m ² /g、600m ² /g to 900m ² /g、900m ² /g to 1300, or 1300m ² /g to 1800m ² Surface area per gram (BET surface area, ASTM D-2414). Carbon black can be used in any end-use application in which carbon black is utilized, for example as a pigment, reinforcing agent, filler, and/or thermal and/or electrical conductor, and can be used in elastomers, plastics, polymers, carbon powders, inks, batteries, adhesives, coatings, and the like.

In the embodiment shown in fig. 1, the tail gas 38 proceeds to a thermal oxidizer 40 where the tail gas is combusted with an oxidizing gas mixture comprising an oxidizing reactant 26A to produce a hot flue gas 42, which oxidizing reactant 26A may be of the same or different composition as the oxidizing reactant 26. The thermal oxidizer 40 may employ any technique known to those skilled in the art, such as a direct fired incinerator, burner, incinerator. Alternatively or additionally, a portion of the tail gas 38 may be directed to a flare and burned without recovering energy from the resulting combustion. The energy in the hot flue gas 42 can be used to provide heat in a variety of unit processes. In fig. 1, energy is used to heat the water in the boiler 44. The resulting steam 45 may be used to drive a turbine, generate electricity, or provide steam heat or steam for any other industrial process. Alternatively or additionally, the hot flue gas 42 may be passed through a heat exchanger where heat from the hot flue gas 42 is used to heat a liquid or gas, such as the feedstock 28, the oxidizing reactant 26, or the oxidizing gas mixture, and/or to dry carbon black pellets made from the carbon black powder 37. As shown in fig. 1, the cooled flue gas 46 exiting the boiler 44 proceeds to a scrubber 47 where SO _x And/or NO _x Is removed. SO (SO) _x Removal may be accomplished via any method known to those skilled in the art. Can be individually or mutually groupedExemplary SO's for use in conjunction _x The removal process includes wet scrubbing with seawater or an aqueous slurry of limestone, lime, or other alkaline sorbents; spray drying the mixture of sorbent and cooled flue gas 46; a dry sorbent injection process wherein a sorbent material, such as powdered slaked lime, is injected into the stream of cooled flue gas 46; and wet sulfuric acid processes, as described in US5108731, the contents of which are incorporated herein by reference. Exemplary NO _x The removal process includes spraying ammonia or urea into the stream of cooled flue gas 46, as well as Selective Catalytic Reactor (SCR) processes known to those skilled in the art, including but not limited to the methods described in US9192891, the entire contents of which are incorporated herein by reference. Alternatively or in addition to the scrubber 47, a selective non-catalytic reactor (SNCR) process may be used to remove NO from the hot flue gas 42, including, but not limited to, the methods described in the' 891 patent _x . Because SCR and SNCR processes operate most efficiently within specific temperature ranges familiar to those skilled in the art (typically 275-500 ℃ and 900-1050 ℃ respectively), these processes may be located at any suitable point in the process between the thermal oxidizer and the scrubber 47. For example, the SNCR 43 may be located between the thermal oxidizer 40 and the boiler 44, wherein only SO occurs in the scrubber 47 _x Removed (fig. 3). Alternatively or additionally, a series of boilers and/or other heat exchangers may replace boiler 44, with appropriate SCR and/or selective non-catalytic reactor (SNCR) processes incorporated at appropriate locations prior to or between the staged heat recovery systems. Alternatively or additionally, catalytic methods as described in EP2561921 (the contents of which are incorporated herein by reference) or commercially available methods such as SNOX from Haldor Topsoe may also be employed ^TM The method. Any means known to those skilled in the art for operating scrubbers may be employed, including spray towers, tray or tray towers, or beds of packing material such as ceramic or stainless steel, which enhance contact between the scrubbing chemical and the scrubbed gas (e.g., cooled flue gas 46).

While the oxidizing reactant 26 and oxidizing reactant 26A may include air, the oxidizing reactant preferably does not include a significant amount of nitrogen, as is present in air. For example, oxidation reactant 26 and/or oxidation reactant 26A may comprise 80-100% oxygen by volume, such as 90-100% oxygen by volume. Such oxygen may be compressed oxygen or more preferably liquid oxygen which is allowed to evaporate. Alternatively or additionally, oxidation reactant 26 and/or oxidation reactant 26A may be produced from air or other gases using pressure swing adsorption or other methods known to those skilled in the art for increasing oxygen concentration (e.g., cryogenic air separation processes). Such a process may leave a small amount of nitrogen, argon, or other gas in oxidation reactant 26 and/or oxidation reactant 26A. In some embodiments, the oxidation reactant 26 comprises up to 40% nitrogen by volume, such as 2% to 30% nitrogen by volume, 3% to 20% nitrogen by volume, or 5% to 10% nitrogen by volume. The less nitrogen is employed in the oxidation reactant 26 and/or the oxidation reactant 26A, the more concentrated the resulting carbon dioxide of the dehydrated flue gas 48. Recycling the flue gas through the furnace carbon black reactor 10 may partially or completely avoid the use of air or other externally supplied gas as a diluent for the oxidation reactant 26 and/or the oxidation reactant 26A, for example, as part of the oxidizing gas mixture, thereby further reducing the use of nitrogen in the system.

The oxidation reactant 26 employed in the carbon black reactor 10 may be different from the oxidation reactant employed in the downstream process of treating the tail gas 38. For example, an alternative oxidation reactant 26A, which may be air or compressed air, may be used to supply the thermal oxidizer 40 (see fig. 2). Alternatively or additionally, alternative oxidation reactants 26A may be used for either or both of the tail gas burner 60 or the thermal oxidizer 40 (fig. 2).

Alternatively or additionally, additional carbon dioxide from a separate source may be directed into combustion zone 12 and/or reaction zone 16. For example, the carbon dioxide 108 can be combined with the oxidation reactant 26 (fig. 5) or dehydrated flue gas 48 (see fig. 6) prior to being directed to the combustion zone 12 and/or the reaction zone 16. Alternatively or additionally, it may be directed to the combustion zone 12 (fig. 2), the reaction zone 16, or both, separately from one or more components of the oxidizing gas mixture.

In alternative embodiments, the tail gas 38 may be directed to several parallel processes in which the tail gas 38 is treated and the energy therein utilized. As shown in fig. 4, the tail gas 38 is split into three streams 38A, 38B, and 38C. Stream 38A is directed to a tail gas combustor 60 for combustion with an oxidizing gas mixture formed by combining oxidizing reactant 26A with dehydrated flue gas 48. The hot flue gas 42A is directed from the tail gas burner 60 to a dryer 62 to indirectly dry the carbon black 37. The hot flue gas 42A is then directed to a boiler 44. Stream 38B is directed to a combustion box 68 of a feed heater 70 for combustion with the aid of an oxidizing gas mixture formed by combining oxidizing reactant 26A with dehydrated flue gas 48. The resulting hot gas is directed to a feedstock heater 70 wherein the feedstock 28 is preheated to a desired temperature and then fed as heated feedstock 31 to the feedstock injection zone 14 (fig. 1). Stream 38C is directed to thermal oxidizer 40. The hot flue gas stream 42A from the dryer 62, the hot flue gas stream 42B from the feed heater 70, and the hot flue gas 42 from the thermal oxidizer 40 may be combined and fed to the boiler 44 from which boiler 44 the cooled flue gas 46 travels to the scrubber 47.

The scrubbed flue gas 46A exiting the scrubber 47, which may have any water vapor content (e.g. 40-50 vol%) produced by the previous unit process, is then dehydrated in a gas dryer 49. The gas dryer 49 may employ equipment known to those skilled in the art to dewater the gas, including direct and indirect methods. The direct method includes contacting the scrubbed flue gas 46A with cooling water in a cooling scrubber or in a venturi mixer and scrubber tank. Alternatively, the scrubbed flue gas 46A may be dehydrated in a heat exchanger using a cooling reactant such as water, ammonia, glycol, or the like, wherein the cooling reactant is recycled through a condenser to remove heat transferred from the scrubbed flue gas 46A. The cooled water 50 may be discharged as waste water 51 and/or recycled for use as at least a portion of the process water 22. As shown in fig. 1, the water from the gas dryer 49 is first cooled in a cooler 54 before being discharged or recycled, and a portion of the resulting cooling water 50 is directed to the gas dryer 49 to dewater the scrubbed flue gas 46A. Fig. 1 also shows that the domestic feed water 23 is combined with the cooling water 50 to form the process water 22. Alternatively, all of the process water 22 may be comprised of the domestic feed water 23. Upon discharge from the gas dryer 49, the resulting dehydrated flue gas 48 may have up to 35% by volume of water vapor, such as up to 30% by volume of water vapor, up to 25% by volume of water vapor, up to 20% by volume of water vapor, or 2% to 15% by volume of water vapor. Alternatively or additionally, the dehydrated flue gas 48 may be further dried by other methods known to those skilled in the art, such as adsorption/desorption on a desiccant-loaded vessel to bring the amount of water vapor up to 2% by volume, for example up to 1% by volume, up to 0.5% by volume, or from 0.2% by volume to 1.5% by volume. The dehydrated flue gas 48 may have up to 40% by volume nitrogen, for example up to 30% by volume nitrogen, up to 20% by volume nitrogen, up to 15% by volume nitrogen, up to 10% by volume nitrogen, up to 5% by volume nitrogen, up to 3% by volume nitrogen, up to 1% by volume nitrogen, up to 0.5% by volume nitrogen, or up to 0.1% by volume nitrogen. The dehydrated flue gas 48 may have up to 1000ppm carbon monoxide, for example up to 800ppm or up to 500ppm carbon monoxide. The dehydrated flue gas 48 may have up to 15% by volume oxygen, for example, 0.5% to 12% by volume, 1% to 10% by volume, 2% to 7% by volume, 0.2% to 5% by volume, up to 3% by volume, or up to 2% by volume oxygen. The dehydrated flue gas 48 can have at least 30% by volume carbon dioxide, such as 40% to 99% by volume, 50% to 98% by volume, 60% to 95% by volume, at least 70% by volume, at least 80% by volume, at least 90% by volume, or at least 95% by volume carbon dioxide.

The dehydrated flue gas 48 may be used in several unit processes in the furnace carbon black reactor 10 as well as downstream processing of the resulting carbon black and other byproducts. For example, it may form part of an oxidizing gas mixture in which the burner fuel 24 is combusted in the combustion zone 12. As shown in fig. 1, may be used as a diluent for the oxidation reactant 26 and/or the oxidation reactant 26A to form an oxidizing gas mixture that is introduced into the thermal oxidizer 40, the combustion zone 12, or a secondary oxidation stream that is introduced into the reaction zone 16 or a subsequent reaction zone as described above. Alternatively or additionally, at least a portion of the dehydrated flue gas 48 may be pressurized. Depending on the desired pressure for the subsequent unit process, it may be advantageous to pressurize the dehydrated flue gas 48, for example, prior to heating the dehydrated flue gas 48 in the heat exchanger 30 or other heat exchanger associated with the furnace carbon black reactor 10 and its downstream processes. In one embodiment, a pump or compressor 82 may be disposed upstream of the heat exchanger 30 after (as shown in FIG. 1) or before (as shown in FIG. 5) any transfer of dehydrated flue gas 48 to the secondary oxidation gas inlet 29. As shown in fig. 1, dehydrated flue gas 48 is used without further heating in the secondary oxidation stream, but passes through compressor 82 and heat exchanger 30 to become heated compressed dehydrated flue gas 56, which is combined with oxidation reactant 26 for introduction into combustion zone 12. Alternatively, the dehydrated flue gas 48 may be heated and/or compressed prior to its use in the secondary oxidation stream and/or not heated prior to introduction into the combustion zone 12 (FIG. 3).

Alternatively or additionally, dehydrated flue gas 48 can be combined with oxidation reactant 26 and the resulting oxidizing gas mixture heated prior to introduction into combustion zone 12, reaction zone 16, or a subsequent reaction zone as described above. As shown in fig. 5, the compressed dehydrated flue gas 57 is heated in a heat exchanger 85 and introduced into the reaction zone 16. Whether heated and/or compressed, the dehydrated flue gas 48 can be introduced directly into the reaction zone 16 (or a subsequent reaction zone as described above) or combustion zone 12 without first mixing 26 with the oxidizing reactant; in this embodiment, the oxidizing gas mixture is formed, for example, in combustion zone 12 or reaction zone 16. For example, in FIG. 3, dehydrated flue gas 48 is injected into combustion zone 12 via secondary oxidizing gas inlet 27A and compressed heated dehydrated flue gas 56 is injected into reaction zone 16 via secondary oxidizing gas auxiliary inlet 29A. In any of these embodiments, the dehydrated flue gas 48 alone or in a mixture with the oxidation reactant 26 may reach a temperature of 400 to 950 ℃. In an alternative embodiment, dehydrated flue gas 48 is combined with a limited amount of oxidizing reactant 26, heated, and then combined with additional oxidizing reactant. In view of the flammability of certain oxidizing reactants, such as oxygen, the amount of oxidizing reactant 26 may be limited to an amount that can be safely contained in the heater.

The compressed dehydrated flue gas 57 may be used to support any process in the furnace carbon black reactor 10 or the associated downstream processes shown in the figures that require compressed gas. For example, the compressed dehydrated flue gas 57 may be used to cool a sight glass or a pilot in the carbon black reactor 10. Alternatively or additionally, it may be used to blow off soot (boot) of the boiler 44 and/or the thermal oxidizer 40. The compressed dehydrated flue gas 57 may be used to blow off soot from the SCR catalyst in the scrubber 47. The increased carbon dioxide concentration also allows the dehydrated flue gas 48 to be used as a process gas (fig. 5) for cleaning the separator 36, preferably after compression into compressed dehydrated flue gas 57, for example, as a purge/counter-flow gas, especially if bag filters or other similar devices are employed, or in cyclones employed in the separator 36. The increased carbon dioxide concentration of the dehydrated flue gas reduces the risk of combustion that may exist if air is employed in the thermal separator 36.

Alternatively or additionally, dehydrated flue gas 48 may be used to further treat carbon black. Carbon black is often compressed into pellets to reduce dust and to facilitate handling. To improve the handling characteristics of relatively fluffy carbon blacks, they are often agglomerated by various mechanical processes to produce pellets, whether in the dry state or with the aid of liquid pelletization aids. Typically, the carbon black particles are held together by weak forces. Methods of granulating carbon black to produce carbon black pellets are known in the art. For example, U.S. patent No.2,065,371 to Glaxner describes a wet granulation process whereby a fluffy carbon black is combined with a liquid, such as water, and stirred until substantially spherical carbon black beads are formed. Typical carbon black pellets are about one millimeter in size. In addition to water, a wide variety of binder additives are known to be useful in wet granulation processes to further improve the pellet handling characteristics of the fluffy carbon black. Such additives include, but are not limited to, hygroscopic organic liquids such as glycols, carbohydrates (e.g., sugars, molasses, soluble starches, sugars, lignin derivatives), rosin, sulfonate and sulfate anionic surfactants, fatty amine ethoxylate nonionic surfactants, sodium lignin sulfonate, silanes, sucrose, alkyl succinimides, alkylated succinates, and polyethylene oxide-co-dimethicone surfactants. The beads are then dried to reduce the moisture content to at most 1% to form carbon black pellets. The dehydrated flue gas 48 may be heated and used to dry the carbon black pellets by direct contact in a dryer. The dehydrated flue gas 48 may be heated in the heat exchanger 30 or using alternative heating methods as described below. For example, in FIG. 3, carbon black 37 is processed in a granulator 87 and then contacted with heated compressed dehydrated flue gas 56 in a dryer 62 to form dried carbon black pellets 37A. Direct contact is possible due to the low flammability and low reactivity of the heated compressed dehydrated flue gas 56, whereas hot air has a higher oxygen content and can create a safety risk if in direct contact with the combustible hot carbon black and the off-gas flammability can create a safety risk if air leaks into the dryer where the hot off-gas contacts the carbon black pellets. The reactivity of the air or tail gas can affect the carbon black characteristics and thus may compromise quality. For example, in fig. 4, dryer 62 operates by indirect contact between carbon black pellets 37 and hot flue gas 42A. For example, the hot flue gas 42A may pass through a duct or other jacket surrounding the housing that separates the carbon black 37 from the hot flue gas 42A.

The increased carbon dioxide concentration of dehydrated flue gas 48 provides several advantages for the operation of furnace carbon black reactor 10 and downstream processes for collecting carbon black and other byproducts. In one embodiment, at least a portion of the dehydrated flue gas 48 may be transferred to a carbon capture system, such as carbon capture system 52. An increase in the partial pressure of carbon dioxide in the dehydrated flue gas 48 may improve the efficiency of the carbon capture system 52. Carbon capture system 52 may include any carbon dioxide separation, utilization, sequestration, and/or storage system known to those skilled in the art, such as, for example, physical adsorption-based methods (e.g., using activated carbon, methanol, glycols, or other solvents that may participate in van der Waals interactions with carbon dioxide), chemical absorption methods (e.g., using amine-based solvents, inorganic alkaline solutions such as potassium carbonate or sodium carbonate, or other chemicals that may form weak chemical bonds with carbon dioxide and are readily regenerated), and/or membrane separation methods (e.g., using ceramic or zeolite membranes). Physical adsorption processes include, but are not limited to, temperature swing adsorption, pressure swing adsorption, and pressure swing adsorption. Carbon dioxide separation may also include drying methods, such as by using coolers, pressure swing adsorption, or other suitable methods to remove water, followed by condensing the carbon dioxide while removing lower boiling point gases such as oxygen and argon. The carbon dioxide separation process may also remove oxygen, for example, unconsumed excess oxygen in the thermal oxidizer 40. After separation, carbon dioxide 90 (FIG. 6) may be injected into the underground brine aquifer or other carbon sequestration aquifer while other remaining gases (mainly water and oxygen, with minor amounts of nitrogen and other gases) 92 are vented. Other methods for carbon dioxide storage known to those skilled in the art may also be employed. Alternatively or additionally, carbon dioxide may be used in industrial and/or commercial processes such as enhanced oil recovery, facilitating fermentation and other biological processes, building material manufacture, fire extinguishers, beverage production, greenhouse cultivation (greenhouse-based agriculture), and other manufacturing and industrial processes that employ carbon dioxide as a process gas or as a raw material. Alternatively or additionally, for example, liquid oxygen designated for use as the oxidation reactant 26 may be used as a cold storage (cold reservoir) to remove heat from and liquefy carbon dioxide. Alternatively or additionally, the heat exchange between the carbon dioxide-enriched stream and liquid oxygen may be configured to facilitate vaporization of the liquid oxygen used as oxidation reactant 26. In this way, even a limited amount of thermal energy remaining in the carbon dioxide rich stream after carbon dioxide separation can be utilized. The increase in the concentration of carbon dioxide in the dehydrated flue gas 48 reduces the amount of other gases that need to be separated from the dehydrated flue gas 48 prior to or during the carbon capture process. Thus, higher concentrations of carbon dioxide in the dehydrated flue gas 48 may reduce the necessary size of the components of the carbon capture system 52.

Alternatively or additionally, at least a portion of the cooled flue gas 46 may be diverted and blended with the dehydrated flue gas 48 prior to the combined flue gas stream being used in the various combustion processes described herein. For example, in FIG. 7, a portion of the cooled flue gas 46 is diverted to a gas dryer 49A to remove water, which is then cooled in a cooler 54A to produce cooled water 50A. The cooled water 50A can be recycled to the gas dryer 49A in the same manner as the cooled water 50 is recycled to the gas dryer 49, or can be used as part of the process water 22. In fig. 7, cooled water 50A is blended with wastewater 51 and discharged. The dried cooled flue gas exiting gas dryer 49A is preferably heated to above 200 ℃ in heater 116 to form recycled flue gas 120, which is then combined with dehydrated flue gas 48 to form flue gas mixture 118. The flue gas mixture 118 may be used in any of the combustion processes described herein or in the furnace carbon black reactor 10 in the same manner as the dehydrated flue gas 48. For example, the flue gas mixture 118 may be combined with the oxidation reactant 26 before or after additional heating (or not employed), such as in the heat exchangers 30 and/or 85, and injected into the combustion zone 12 and/or the reaction zone 16, or may be injected into the combustion zone 12 and/or the reaction zone 16 separately from the oxidation reactant 26.

With respect to the dehydrated flue gas 48, the flue gas mixture 118 may be compressed to achieve a desired pressure. For example, in fig. 7, the flue gas mixture 118 is compressed in the compressor 82 to produce a compressed flue gas mixture 123 that is combined with the carbon black-yielding feedstock 28 and directed to the feedstock heater 30, and is also combined with the oxidation reactant 26 and directed to the reaction zone 16. The compressed flue gas mixture 123 also passes through the heat exchanger 30 and the resulting heated compressed flue gas mixture 124 is combined with the oxidation reactant 26 and directed to the combustion zone 12. In certain embodiments, the cooling flue gas 46 need not be dehydrated, in which case the heater 116 may also be omitted. The amount of cooled flue gas 46 that can be diverted depends on whether the cooled flue gas 46 is dehydrated (which will change the partial pressure of water vapor) prior to combining with the dehydrated flue gas 48, the amount of dehydrated flue gas 48 diverted to the carbon capture system 52, the composition of the oxidation reactants 26 and 26A, and the desired composition of the oxidation gas mixture. However, the diversion of a portion of the cooled flue gas 46 will reduce the size required of the scrubber 47 and the gas dryer 49. In certain embodiments, the hot flue gas 42 may pass through the SNCR 43 prior to the boiler 44, thereby reducing the diverted cooled flue gas 4 NO in 6 _x Is a combination of the amounts of (a) and (b).

Alternatively or additionally, the dehydrated flue gas 48 or flue gas mixture 118 may be used as an atomizing gas for injecting the carbon black-yielding feedstock into the feedstock injection zone 14 or a subsequent feedstock injection zone as described above (FIG. 1). In embodiments where additional feedstock is injected into one or more reaction zones, such as reaction zone 16, dehydrated flue gas 48 or flue gas mixture 118 may additionally be used as an atomizing gas. In any of these embodiments, it may be desirable to preheat the dehydrated flue gas 48 or flue gas mixture 118. In FIG. 2, a portion of the dehydrated flue gas 48 passes through the heat exchanger 30 to form a heated dehydrated flue gas 58 that is combined with the oxidation reactant 26 and injected into the combustion zone 12. Alternatively or additionally, dehydrated flue gas 48 may be combined with feedstock 28 and the mixture passed through a heat exchanger, such as heat exchanger 70 (FIG. 3). In fig. 2, the heated dehydrated flue gas 58 is combined with the sooting feedstock 28 and the resulting mixture is directed to the feedstock injection zone 14. In any of these embodiments, the flue gas mixture 118 may be employed in the same manner as the dehydrated flue gas 48. For example, in fig. 7, the flue gas mixture 118 is compressed to form a compressed flue gas mixture 123 that is combined with the oxidizing reactant 26 to form an oxidizing gas mixture. The compressed flue gas mixture 123 is also heated in the heat exchanger 30 to form a heated compressed flue gas mixture 124 that is combined with the oxidation reactant 26 and directed to the reaction zone 16.

Alternatively or additionally, the increased carbon dioxide content of the dehydrated flue gas 48 and/or flue gas mixture 118 enables additional techniques for heating the dehydrated flue gas 48 and/or flue gas mixture 118 as desired, such as prior to injection into the combustion zone 12 or reaction zone 16, prior to mixing with the oxidation reactant 26, or prior to use as an atomizing gas for the carbon black production feedstock 28. This may reduce or eliminate the need for combustion techniques to heat the carbon black yielding feedstock 28 or the oxidation reactant 26. Due to the low hydrocarbon and limited oxidation content of the dehydrated flue gas 48 and flue gas mixture 118, they may be heated not only by combustion methods, but also by electrically powered methods such as resistive heating elements, microwaves, or thermal plasmas, such as direct arc plasmas. For example, the dehydrated flue gas 48 and flue gas mixture 118, with or without compression, may be directly heated with an electrically powered heating element capable of supplying energy at high temperatures. Preferably, the heating element is fabricated from corrosion and high temperature resistant materials such as zirconia, molybdenum carbide, silicon carbide, and other such materials known to those skilled in the art. Likewise, microwaves or electric current may be passed through the dehydrated flue gas 48 or flue gas mixture 118. Generating plasma by current; microwave heating may also generate a plasma, depending on the microwave energy.

Furthermore, the use of dehydrated flue gas 48 or flue gas mixture 118 as a carrier gas or as part of an oxidizing gas mixture potentially reduces the amount of gas delivered to combustion zone 12 in proportion to the desired amount of oxygen. Although air is only about 21% oxygen by volume, the synthesis gas produced with dehydrated flue gas 48 or flue gas mixture 118 (with or without compression and/or heating) and purified (e.g., compressed or liquefied/vaporized) oxygen can have any proportion of oxygen, thereby reducing the total amount of gas required and substantially concentrating the carbon black content of the product stream. The reduction in the amount of gas used to carry the carbon black product can increase reactor throughput by allowing more carbon black to be produced for a given volume of product stream. Furthermore, an increase in the carbon dioxide content of the dehydrated flue gas 48 or flue gas mixture 118 as compared to air may increase the amount of carbon black that can be produced from a given amount of carbon black production feedstock (yield efficiency).

The oxidizing gas mixture in which the combustor fuel 24 is combusted may include 20-85 volume percent carbon dioxide, 15-80 volume percent oxygen, up to 30 volume percent water vapor, and up to 35 volume percent nitrogen. Other materials may also be present in small amounts, such as argon, NO _x 、SO _x CO, and other components common in compressed oxygen, compressed nitrogen, flue gas, and air. For example, the oxidizing gas mixture may include 30-80 vol%, 40-75 vol%, 45-70 vol%, or 50-60 vol% carbon dioxide. Alternatively or additionally, the oxidizing gas mixture may include 20-70% or 25-60% or 30-50% oxygen by volume. Alternatively, the method comprisesAlternatively, or in addition, the oxidizing gas mixture may include 0.1-20 vol%, 0.5-15 vol%, 1-10 vol%, or 2-5 vol% water. Alternatively or additionally, the oxidizing gas mixture may include 2% to 35% by volume nitrogen, 4% to 25% by volume nitrogen, 5% to 15% by volume, or up to 10% by volume nitrogen.

Where at least a portion of the cooled flue gas 46 is recycled, the dehydrated flue gas 48 need not be recycled to the furnace carbon black reactor 10. Instead, dehydrated flue gas 48 may be directed to carbon capture system 52, and a portion optionally diverted for use as a process gas as described above (fig. 8), e.g., for cleaning scrubber 47, cooling a sight glass, drying carbon black pellets, for use in separator 36, etc. As shown in fig. 8, the cooled flue gas 46 is not even dried and reheated, but rather is recycled directly to the combustion zone 12, reaction zone 16, and thermal oxidizer 40 in the same manner as the dehydrated flue gas 48 or flue gas mixture 118. Likewise, the cooled flue gas 46 may serve as a diluent or carrier for the oxidation reactant 26A in the tail gas combustor 60 or the oxidation reactant 26 in the feed heater 70. The cooled flue gas 46 may be heated, pressurized, and combined with the oxidation reactant 26, or injected separately into the combustion zone 12 and/or the reaction zone 16 in the same manner as described above for the dehydrated flue gas 48 and the flue gas mixture 118. For example, in FIG. 8, the cooled flue gas 46 is compressed in a compressor 82. The resulting compressed cooled flue gas 93 is combined with feedstock 28 and directed to feedstock heater 70, and is also combined with oxidation reactant 26 and directed to combustion zone 12. The compressed cooled flue gas 93 is heated in the heat exchanger 30 and the resulting heated compressed cooled flue gas 94 is combined with the oxidation reactant 26 and directed to the reaction zone 16.

The use of a low nitrogen oxidizing gas mixture also allows for the more advantageous use of tail gas 38. For example, a decrease in nitrogen concentration also increases the proportion of hydrogen in the tail gas 38. Alternatively or additionally, at least a portion of the tail gas 38 may be dehydrated in the tail gas processor 100 (FIG. 6) to produce dehydrated tail gas using methods known to those skilled in the art, such as those described above for dehydrating flue gas. The resulting liquid water 102 may be directed to the process water 22, the wastewater 51, or combined with the cooling water 50 for use in the gas dryer 49 (and the gas dryer 49A in embodiments where the cooled flue gas 46 is dehydrated and recycled).

Any method known to those skilled in the art, including hydrogen permeable membranes, pressure swing adsorption, and other swing methods, may be used to remove hydrogen from the exhaust gas before or after dehydration, optionally in the exhaust gas processor 100. The resulting hydrogen 104 may be recycled for various uses including as a rocket fuel, power generation in a fuel cell (e.g., for zero emission vehicles), hydrodesulfurization of fossil fuels, hamburg-bosch synthesis for producing ammonia, as a reducing agent for recovering metals such as tungsten and copper from various ores, and hydrogenation of fats and oils for food products, production of chemicals such as methanol and hydrogen peroxide, and other industrial processes. After dehydration and optional hydrogen removal, the treated tail gas 106 may be combusted, for example, in a device similar to the tail gas combustor 60, the combustion box 68, or the thermal oxidizer 40. In embodiments where hydrogen is removed from the tail gas 38, the primary combustible gas in the treated tail gas 106 is carbon monoxide, thereby further reducing the amount of oxidant (e.g., the oxidizing reactant 26A) required to combust the tail gas.

Alternatively or additionally, the increase in concentration of hydrogen and carbon monoxide in the tail gas 38 as compared to the tail gas generated using air in the carbon black reactor 10 makes the tail gas 38 particularly suitable for reuse as at least a portion of the burner fuel 24 after dehydration (fig. 6). For example, at least a portion of the dehydrated tail gas can be redirected to the combustion zone 12, with any remaining dehydrated tail gas optionally being treated to remove hydrogen prior to combustion or other oxidation or carbon monoxide removal. Alternatively, at least a portion 38 of the tail gas may be recycled directly to the combustion zone 12 without dehydration and/or without hydrogen removal. Because the dehydrated tail gas still contains carbon monoxide (in addition to any residual hydrogen) after optional hydrogen removal, it can still be advantageously redirected to the combustion zone 12. In any embodiment in which at least a portion of the tail gas 38 (with or without one or more of dehydration and hydrogen removal) is recycled to the combustion zone 12, the thermal oxidizer 40 requires a reduced amount of the oxidizing reactant 26A because the lower volume of gas is treated. Furthermore, the recycling of the tail gas results in a lower amount of flue gas to be treated in the scrubber 47. Fig. 6 shows the exhaust gas processor 100 separate from the transfer of the exhaust gas 38 to the exhaust gas burner 60, the combustion box 68 and the thermal oxidizer 40. However, it may be desirable to dehydrate and even remove hydrogen from the tail gas 38 and utilize the treated tail gas 106 in the tail gas burner 60, the combustion box 68, and the thermal oxidizer 40.

Alternatively or additionally, at least a portion of the tail gas 38 may be pressurized. The apparatus using compressed tail gas may be operated at higher pressures or may be smaller, or both, because of the smaller volume of the tail gas. For example, the use of compressed tail gas from compressor 112 (FIG. 5) in thermal oxidizer 40 will result in a higher pressure of hot flue gas 42 and thus dehydrated flue gas 48. Alternatively or additionally, the portion of the tail gas 38 that is to be directed to the combustion zone 12 may be compressed. It may be advantageous to dehydrate all or a portion of the tail gas 38 prior to compression. For example, the tail gas 38 may first be treated in the tail gas processor 100 to reduce the water vapor and optionally hydrogen content prior to compression, as shown for the compressor 110 (fig. 6). The tail gas 38 may also be similarly treated prior to being directed to the compressor 112.

Examples

Two typical carbon black product grade production processes were simulated based on empirical furnace operating parameters, carbon black product yield correlation, and the like. Two types of CB grades that are simulated include semi-reinforcing grades of ASTM N-500 and 600 series carbon blacks (low surface area, or LS carbon blacks) and reinforcing grades of ASTM N-100 to 300 series carbon blacks (high surface area, or HS carbon blacks).

Similar feed and natural gas fuels were used for all simulated production processes. Their characteristics can be represented in tables 1 and 2, respectively.

Table 1. Natural gas fuel properties used in cb production process simulation

Component (A)	Composition (vol%)
		CH ₄	93.330％
C ₂ H ₆	3.867％
		Propane	0.243％
Butane	0.060％
		Pentane	0.059％
Hexane	0.039％
		N ₂	0.437％
CO ₂	1.965％
		Low Heating Value (LHV) (MJ/Nm) ³ )	36.32

TABLE 2 characterization of raw materials used in simulation of CB production process

Characteristics of	Value of
		Elemental composition	Weight percent
H	8.45％
		C	88.45％
N、O、S	Allowance of
		Specific gravity	1.13

Comparative example 1: LS (Low surface area) carbon black production

In this example, a furnace carbon black reactor 10 as shown in FIG. 9 was used to produce a carbon black product. Natural gas is used as burner fuel 24 which is combusted with combustion air 126 supplied by a blower 128. The preheated combustion air 126 combusts natural gas in the combustion zone 12 to form a main flame and generates gas (main flame gas 130) that is transferred from the combustion zone 12 to the feedstock injection zone 14. Feed 28 (decant oil as listed in table 2) is preheated to 240 ℃ and then injected into the main flame through one or more nozzles in feed injection zone 14 to produce a hot flue gas stream containing the desired carbon black product entrained in the hot by-product gas stream. Water is directed through a first stage injector 20 at about 10-15m downstream of the feedstock injection zone 14 to terminate the reaction, and then the quenched reactor product stream is passed through a heat exchanger The heater 30 preheats ambient air to generate combustion air 126. The cooled reactor product stream is further cooled to about 230 ℃ in cooling zone 32 and transferred to bag filter 36A to separate solid carbon black 37 and produce tail gas 138. Using air 126A as the oxidant, tail gas 138 having a significant heating value is combusted in thermal oxidizer 40 to generate heat (about 29MW in the model of this embodiment) for process heating and/or heat recovery for steam production. The combustion of the tail gas 138 is controlled such that the volatile organic compounds are completely destroyed to meet applicable environmental regulations, while at the same time minimizing the excess oxygen concentration in the hot flue gas 142 to maximize thermal efficiency, and/or minimizing flue gas flow to reduce the design capacity of downstream air pollution control units, such as SNCR (not shown) and/or scrubber 47, including a gas dryer 49 having a cooling power of about 17.6MW to dehydrate the scrubbed flue gas 146A and form dehydrated flue gas 148. Stream 148 is sent to CO ₂ A capture unit 52 to capture CO therefrom ₂ For sequestration, enhanced oil recovery (oil recovery), or other uses.

Table 3 summarizes the key process parameters for the production of LS grade carbon black following this process.

TABLE 3 key process parameters for example 1

Table 3 (subsequent)

Table 4: composition and Properties of several key gas streams of comparative example 1

In this comparative example, 49,429Nm ³ Dehydrated flue gas 148 at CO/h ₂ The capturing unit is processed. The gas stream contains 8.06% by volume of CO ₂ (Table 4).

Example 2: LS (Low surface area) carbon black production according to exemplary embodiments of the present invention

In this example, a carbon black product was produced using a furnace carbon reactor 10 having a similar configuration as that employed in comparative example 1, but employing flue gas recycle, as shown in fig. 10. Natural gas is used as burner fuel 24 which is combusted with an oxidizing gas mixture formed from a mixture of an oxygen stream 26 as an oxidizing reactant and dehydrated flue gas 48A. In this example, the oxygen stream contains 3% by volume of N ₂ And 97% by volume of O ₂ . The ratio of oxygen and dehydrated flue gas in the oxidizing gas mixture was adjusted so that the main flame temperature was intended to be close to the temperature used in comparative example 1. The flow of dehydrated flue gas 48A is adjusted so that the flow of the stream of main flame 131 is intended to be close to example 1.

The resulting tail gas 38 was also mixed with oxygen oxidation reactant 26A (97 vol% O) mixed with dehydrated flue gas 48B ₂ And 3% by volume N ₂ ) Together to a level intended for the desired flame temperature and excess oxygen concentration in the hot flue gas 42 and to generate about 28.6MW of thermal energy. Similar to comparative example 1, the hot flue gas 42 from the combustion of the tail gas 38 will be cooled in a boiler 44 to produce steam 45. In NO _x And SO _x After removal to the desired allowable level, the scrubbed flue gas 46A is dehydrated at 40 ℃ (the cooling power for dehydration is about 19.9 MW). The resulting slip stream (slip stream) of dehydrated flue gas 48 is partially (48A) recycled back to mix with oxygen to form an oxidizing gas mixture and preheated to a desired temperature in heat exchanger 30 prior to entering the burner. Stream 48B is a slip stream of dehydrated flue gas 48 that is recycled back to be mixed with oxidation reactant 26A for use as an oxidant for thermal oxidizer 40. The remainder ofDehydrated flue gas 48 is sent to CO ₂ Capturing unit 52 to remove CO ₂ . Table 5 below summarizes the key parameters of this example.

TABLE 5 Key process parameters for example 2

Table 5 (subsequent)

Table 6: composition and Properties of several Key gas streams of example 2

In this embodiment, the process is required in CO ₂ The dehydrated flue gas treated in the capture unit was 4,697nm ³ And/h. The gas stream contains 84.86% by volume of CO ₂ (Table 6).

Comparative example 3: HS (high surface area) carbon black production

In this comparative example 3, high surface area grade carbon black was produced using the conventional formulation as described in example 1, but with a quench length of about 1-10m. Carbon black product treatment, tail gas combustion, energy recovery and flue gas treatment generally follow the same protocol as shown in example 1. Table 7 below summarizes the key process parameters for this example. Combustion of the tail gas 138 results in about 36.9MW of thermal energy and requires about 25.6MW of cooling power to dehydrate the scrubbed flue gas 146A.

Table 7: critical process parameters of example 3

Table 7 (subsequent)

Table 8: composition and Properties of several key gas streams of comparative example 3

In this comparative example, 60,588Nm ³ Dehydrated flue gas at CO/h ₂ The capturing unit is processed. The gas stream contains 10.18% by volume of CO ₂ (Table 8).

Example 4: HS (high surface area) carbon black production according to exemplary embodiments

In this example 4, a high surface area grade carbon black was produced using a similar process as described in example 2, but with a quench length of 1-10m. Carbon black product treatment, tail gas combustion, energy recovery and flue gas treatment generally follow the same protocol as shown in example 2. Table 9 below summarizes the key process parameters for this example. Combustion of the tail gas 38 results in about 39.3MW of thermal energy and requires about 27.1MW of cooling power to dehydrate the scrubbed flue gas 46A.

Table 9: key process parameters of example 4

Watch 9 (subsequent)

TABLE 10 composition and Properties of several key gas streams for example 4

In this example, 7,410Nm ³ Dehydrated flue gas at CO/h ₂ The capturing unit is processed. The gas stream contains 85.08% by volume of CO ₂ (Table 10).

Example 5: HS (high surface area) carbon black production according to exemplary embodiments

In this example 5, the same equipment as in example 4 was used to produce high surface area grade carbon black. Instead of pure oxygen, oxygen-enriched air (containing 40% by volume of O ₂ And 60% by volume N ₂ ) Is used as the oxidizing reactant 26A in the thermal oxidizer 40. The oxidation reaction 26 contained 3% by volume N ₂ And 97% by volume O ₂ . Carbon black product treatment, tail gas combustion, energy recovery and flue gas treatment generally follow the same protocol as shown in example 2. Table 11 below summarizes the key process parameters for this example. Combustion of the tail gas 38 results in about 39MW of thermal energy and requires about 29MW of cooling power to strip the scrubbed flue gas 46AAnd (3) water.

Table 11: key process parameters of example 5

Watch 11 (subsequent)

TABLE 12 composition and Properties of several key gas streams for example 5

Example 6: HS (high surface area) carbon black production according to exemplary embodiments

In this example 6, high surface area grade carbon black was produced using the same equipment as in example 4. In this example, a composition (3% by volume N) of an oxidation reactant 26 and an oxidation reactant 26A similar to those in example 4 was used ₂ And 97% by volume O ₂ ). This example demonstrates the effect of higher moisture content in dehydrated flue gas 48 dehydrated at 55 ℃. The key process parameters for this example are summarized in table 13 below. Combustion of the tail gas 38 results in about 41MW of thermal energy and requires about 29MW of cooling power to dehydrate the scrubbed flue gas 46A.

Table 13: critical process parameters of example 6

Watch 13 (subsequent)

TABLE 14 composition and Properties of several key gas streams for example 6

Example 7: LS (Low surface area) carbon black production according to exemplary embodiments

In this example 7, the same equipment as in example 2 was used to produce low surface area grade carbon black. Instead of pure oxygen, air is used as the oxidation reactant 26. Oxidation reactant 26A contained 3% N by volume ₂ And 97% by volume O ₂ . Carbon black product treatment, tail gas combustion, energy recovery and flue gas treatment generally follow the same protocol as shown in example 2. Table 15 below summarizes the key process parameters for this example. Combustion of the tail gas 38 results in about 28MW of thermal energy and requires about 19MW of cooling power to dehydrate the scrubbed flue gas 46A.

Table 15: critical process parameters of example 7

Watch 15 (Xuezhi)

TABLE 16 composition and Properties of several key gas streams for example 7

The foregoing description of the preferred embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. Those skilled in the art will recognize that the various embodiments described herein and schematically depicted in the drawings provide a wide variety of alternative system configurations. It is contemplated that the skilled artisan will be able to readily adjust the configuration and process parameters for the desired operation of the furnace carbon black reactor according to various embodiments of the present invention, with the benefit of the present disclosure. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Claims

1. A process for producing carbon black comprising:

(a) Converting a hydrocarbon feedstock to carbon black in at least one feedstock injection zone downstream of a combustion zone, and at least one reaction zone downstream of a first feedstock injection zone, in the presence of combustion gases generated in the combustion zone by combusting the fuel in an oxidizing gas mixture comprising 20-85% by volume carbon dioxide, 15-80% by volume oxygen, up to 30% by volume water, and up to 35% by volume nitrogen, in the reaction zone to form a first product stream comprising carbon black, carbon dioxide, carbon monoxide, water vapor, and hydrogen, wherein the fuel is part of the hydrocarbon feedstock or a separate fuel source, and wherein at least part of the hydrocarbon feedstock is contacted with the combustion gases in the at least one feedstock injection zone;

(b) Adding water to the first product stream to at least partially stop the conversion and form a second product stream comprising carbon black, carbon dioxide, carbon monoxide, hydrogen, and water vapor;

(c) Removing the carbon black from the second product stream to form an off-gas;

(d) Reducing the carbon monoxide and hydrogen content in at least a portion of the tail gas to produce a flue gas comprising up to 40% by volume nitrogen; and

(f) At least a first portion of the flue gas is directed to at least one of the combustion zone, the at least one feedstock injection zone, and the at least one reaction zone.

2. The method of claim 1, wherein the first product stream further comprises sulfur-containing species, and the method further comprises removing at least a portion of the sulfur-containing species from the first portion of the flue gas, the second portion of the flue gas, or both.

3. The method of claim 1, wherein reducing comprises combusting the tail gas.

4. The method of claim 1, wherein reducing comprises separating and recovering at least a portion of hydrogen from the tail gas.

5. The method of claim 4, wherein the first and second product streams each contain carbon monoxide, and wherein reducing further comprises combusting the tail gas after separation and recovery.

6. The method of claim 4, further comprising removing water from the tail gas prior to removing hydrogen.

7. The method of claim 6, wherein the removed water is directed for use in step (b).

8. The method of claim 1, wherein the method further comprises directing at least a portion of the tail gas to the combustion zone.

9. The method of claim 8, further comprising removing water from the tail gas prior to directing at least a portion of the tail gas.

10. The method of claim 9, wherein the removed water is directed for use in step (b).

11. The method of claim 1, further comprising combining the first portion of the flue gas with an oxidizing reactant prior to directing, wherein the oxidizing gas mixture comprises the combined first portion of the flue gas and oxidizing reactant, and wherein the combined portion of the flue gas and oxidizing reactant is directed to the combustion zone, the reaction zone, or both.

12. The method of claim 11, further comprising heating the first portion of the flue gas prior to combining.

13. The method of claim 11, further comprising heating the combined first portion of the flue gas and the oxidizing reactant.

14. The method of claim 1, further comprising heating the first portion of the flue gas prior to directing.

15. The method of claim 1, further comprising combining the first portion of the flue gas with the hydrocarbon feedstock prior to directing, wherein the combined portion of the flue gas and hydrocarbon feedstock is directed to the at least one feedstock injection zone.

16. The method of claim 15, further comprising heating the combined first portion of the flue gas and hydrocarbon feedstock.

17. The method of claim 15, further comprising heating the first portion of the flue gas to form a hot flue gas and combining the hot flue gas with the hydrocarbon feedstock prior to directing.

18. The method of claim 1, further comprising heating the first portion of the flue gas with an energy source selected from the group consisting of microwaves, plasmas, and resistive heating elements.

19. The method of claim 1, further comprising removing water from the first portion of the flue gas to produce dehydrated flue gas comprising up to 35% by volume of water.

20. The method of claim 19, wherein the removed water is directed for use in step (b).

21. The method of claim 19, further comprising granulating at least a portion of the carbon black by: combining the portion with a liquid to form carbon black beads, and drying the carbon black beads to reduce the moisture content to at most 1 wt%, wherein drying comprises heating the dehydrated flue gas and contacting the carbon black beads with the heated dehydrated flue gas.

22. The method of claim 21, wherein the liquid comprises the removed water.

23. The method of claim 19, further comprising diverting a portion of the dehydrated flue gas and removing at least a portion of carbon dioxide from the diverted dehydrated flue gas.

24. The method of claim 22, further comprising either or both of condensing and storing carbon dioxide removed from the diverted dehydrated flue gas.

25. The method of claim 19, further comprising providing the oxidizing gas by allowing liquid oxygen to evaporate, wherein the method further comprises transferring thermal energy from the dehydrated flue gas to the liquid oxygen.

26. The method of claim 19, wherein removing the carbon black comprises passing the second product stream through a filter that separates the second product stream into carbon black and tail gas, wherein the method further comprises purging solid particulates from the filter with the dehydrated flue gas.

27. The method of claim 19, wherein removing the carbon black comprises passing the second product stream through a cyclone, wherein the method further comprises separating the tail gas and the carbon black in the cyclone with a portion of the dehydrated flue gas.

28. The method of claim 19, further comprising compressing at least a portion of the dehydrated flue gas.

29. The method of claim 28, wherein removing the carbon black comprises passing the second product stream through a filter, and wherein the method further comprises cleaning the filter using the compressed dehydrated flue gas.

30. The method of claim 28, wherein reducing comprises combusting the tail gas in a combustor, and wherein the method further comprises using the compressed dehydrated flue gas to clean the combustor.

31. The method of claim 1, wherein adding water further comprises adding at least a portion of the first portion of the flue gas to the first product stream to stop the conversion.

32. A carbon black formed by the method of any one of claims 1-31.

33. An apparatus for producing carbon black comprising:

a carbon black reactor, the carbon black reactor comprising: a combustion zone for combusting an oxidizing gas mixture and a fuel to produce a heated gas stream; a first feedstock injection zone for injecting a hydrocarbon feedstock into the heated gas stream to form a product stream; a first reaction zone within which carbon black is formed in the product stream; a first quench ejector; and a first quench zone within which carbon black is at least partially quenched with quench fluid injected into the product stream from the first quench injector;

A separator in fluid communication with the first quench zone, wherein the carbon black is separated from the product stream to form a tail gas;

a thermal oxidizer configured to combust the tail gas with additional oxidizing gas to form a hot flue gas;

a first flue gas heat exchanger that removes thermal energy from the hot flue gas and has an outlet that discharges cooled flue gas; and is also provided with

Wherein the outlet is in fluid communication with and upstream of at least one plant element selected from the combustion zone and the first reaction zone.

34. The plant of claim 33, further comprising a scrubber cooler comprising a sulfur species scrubber and a water condenser, the scrubber cooler configured to remove sulfur species and water from at least a portion of the cooled flue gas, thereby producing dehydrated flue gas, and comprising a discharge port through which the dehydrated flue gas is discharged, wherein the discharge port is in fluid communication with the at least one plant element.

35. The apparatus of claim 34, further comprising a heater in fluid communication with the discharge of the scrubber cooler, and a carbon black pelletizer configured to receive at least a portion of the heated dehydrated flue gas from the heater, wherein the heated dehydrated flue gas dries carbon black pellets formed in the pelletizer.

36. The apparatus of claim 34, wherein the separator comprises a bag filter, and the apparatus is operable to direct at least a portion of the dehydrated flue gas to periodically purge particulate solids from the bag filter.

37. The apparatus of claim 34, further comprising a carbon capture system operable to remove at least a portion of carbon dioxide present in the dehydrated flue gas.

38. The apparatus of claim 33, wherein the heat exchanger is a boiler, wherein thermal energy from the hot flue gas is transferred to water.

39. The apparatus of claim 33, further comprising a compressor configured to receive at least a portion of the flue gas from the outlet and to discharge compressed flue gas.

40. The apparatus of claim 33, wherein the apparatus is configured to direct at least a portion of the tail gas to the combustion zone.

41. The apparatus of claim 40, further comprising a condenser upstream of the combustion zone, the condenser configured to remove water from the portion of the tail gas.

42. The apparatus of claim 40, further comprising a hydrogen removal device upstream of the combustion zone, the hydrogen removal device configured to remove hydrogen from the portion of the tail gas.

43. The apparatus of claim 33, further comprising a second quench injector and a second quench zone, wherein at least a portion of the quenched carbon black is further quenched with a quench fluid injected into the product stream from the second quench injector.

44. The apparatus of claim 33, further comprising a heater disposed between the outlet and the at least one apparatus element to heat at least a portion of the flue gas, the heater comprising a microwave source, a plasma source, or a resistive heating element.

45. The apparatus of claim 33, further comprising a heat exchanger that receives the product stream from the first quench zone, wherein the heat exchanger is operable to exchange heat of the product stream with at least a portion of the cooled flue gas to heat the portion of the cooled flue gas to a temperature of 400 to 950 ℃.

46. The apparatus of claim 33, wherein the apparatus is configured to combine at least a portion of the cooled flue gas with additional oxidizing gas and to direct the combined portion of the cooled flue gas and additional oxidizing gas to the thermal oxidizer.

47. The apparatus of claim 33, wherein one or more of the combustion zone, the first reaction zone, and the first feedstock injection zone are configured to receive the oxidizing gas mixture, wherein the oxidizing gas mixture comprises at least a portion of the mass of the cooled flue gas and oxidizing reactant.