SYSTEMS AND METHODS FOR MAINTAINING SULFUR CONCENTRATION IN A SYNGAS TO REDUCE METAL DUSTING IN DOWNSTREAM COMPONENTS

Abstract

Systems and methods for maintaining a sulfur concentration in a syngas are provided. The method can include combining sulfur and a carbonaceous material to produce a sulfur containing carbonaceous feed. The method can also include gasifying at least a portion of the sulfur containing carbonaceous feed to produce a syngas and detecting a sulfur concentration in the syngas. The method can further include adjusting an amount of the sulfur combined with the carbonaceous material based on the detected sulfur concentration.

Description

BACKGROUND

1. Field

Embodiments described generally relate to systems and methods for producing synthesis gas. More particularly, such embodiments relate to systems and methods for maintaining sulfur concentration in a syngas to reduce metal dusting in downstream components.

2. Description of the Related Art

A gasifier produces synthesis gas or “syngas” and the syngas can be further processed downstream. Downstream components made of metal, such as exchanger tubes, can suffer from metal dusting, also known as carburization, due to interaction with the syngas, particularly at high temperatures. The term “metal dusting” refers to severe and aggressive corrosion that can disintegrate metal into dust or powder.

Various approaches have been used to reduce the causes and/or effects of metal dusting. One approach has been selecting alloys that are resistant to metal dusting for use in the downstream components. Another approach has been to apply a coating to the downstream components with a coating material that minimizes metal dusting. These two approaches, however, require expensive modifications and/or replacement of components used in existing gasifier systems.

Sulfur is a known inhibitor of metal dusting. The sulfur can be absorbed onto the surface of the metal and block gas to metal transfer of carbon. Typical feeds to a gasifier, e.g., coal or carbonaceous feedstock, contain sulfur. The sulfur levels in these gasifier feeds, however, can be below the minimum level of sulfur needed to reduce or prevent metal dusting.

There is a need, therefore, for systems and methods for producing a syngas with a sulfur concentration sufficient to reduce metal dusting in components downstream of the gasifier.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic of an illustrative gasification system for producing a syngas having a sulfur concentration sufficient to reduce metal dusting in components downstream of one or more gasifiers, according to one or more embodiments described.

FIG. 2 depicts a schematic of another illustrative gasification system for producing a syngas having a sulfur concentration sufficient to reduce metal dusting in components downstream of one or more gasifiers, according to one or more embodiments described.

DETAILED DESCRIPTION

Systems and methods for maintaining a sulfur concentration in a syngas are provided. The method can include combining sulfur and a carbonaceous material to produce a sulfur containing carbonaceous feed. The method can also include gasifying at least a portion of the sulfur containing carbonaceous feed to produce a syngas and detecting a sulfur concentration in the syngas. The method can also include adjusting an amount of the sulfur combined with the carbonaceous material based on the detected sulfur concentration.

FIG. 1 depicts a schematic of an illustrative gasification system 100 for producing a syngas via line 151 having a sulfur concentration sufficient to reduce metal dusting in components downstream of a gasifier 150, according to one or more embodiments. The gasification system 100 can include one or more lock hoppers or storage bins 110, 130 for feeding one or more gasifier feed systems 140, wherein the gasifier feeds can be stored or treated prior to entering the one or more gasifiers 150 to produce syngas. Elemental sulfur can be stored in one or more “first” lock hoppers or storage bins 110, which can be any unit adapted to retain and/or dispense sulfur. One or more feeders 120 can dispense the sulfur from the first lock hopper 110 via line 122 to one or more “second” lock hoppers or storage bins 130 for storing the feedstock for gasification to combine the sulfur with the feedstock.

Although not shown, the feeder 120 can dispense sulfur from the first lock hopper 110 onto and/or into a conveyance device that, in turn, can transport or convey sulfur to the second lock hopper 130. For example, the conveyance device can be a conveyor belt, a slide, a chute, an incline, or a combination thereof. The conveyance device can further control the rate of sulfur dispensed into the second lock hopper 130. For example, if the conveyance device is a conveyor belt, the speed of the belt can be adjusted to dispense sulfur either slowly or rapidly, depending, for example, on sulfur amounts measured further along in the system.

The second lock hopper 130 can receive, store, and/or mix the feedstock and the sulfur so that a sulfur containing carbonaceous material can be obtained therein. The second hopper 130 can convey or dispense the sulfur containing carbonaceous material via line 131 to the gasifier feed system 140. Preferably, the sulfur containing carbonaceous material can be conveyed from the second lock hopper 130 to the gasifier feed system 140 via line 131 at a rate of at least 50 kilograms per hour (kg/hr), and more preferably at a rate between a low of about 75 kg/hr, about 100 kg/hr, or about 125 kg/hr and a high of about 450 kg/hr, about 500 kg/hr, or about 550 kg/hr. The second lock hopper 130 can include a feeder (not shown), such as a high-pressure rotary feeder, that can cooperate with an added fluid stream (not shown) to convey the sulfur containing carbonaceous material via line 131 to the gasifier feed system 140.

The term “feedstock” as used herein refers to one or more carbonaceous materials, whether solid, gas, liquid, or any combination thereof. The feedstock can include one or more carbonaceous materials (i.e., carbon-containing materials) including, but not limited to, biomass (i.e., plant and/or animal matter or plant and/or animal derived matter), coal (i.e., high-sodium and low-sodium lignite, lignite, subbituminous, and/or anthracite), oil shale, coke, tar, asphaltenes, low ash or no ash polymers, hydrocarbon-based polymeric materials, biomass derived material, by-product derived from manufacturing operations, or any combination thereof. The hydrocarbon-based polymeric materials can include, but are not limited to, thermoplastics, elastomers, rubbers, including polypropylenes, polyethylenes, polystyrenes, including other polyolefins, homo polymers, copolymers, block copolymers, PET (polyethylene terephthalate), poly blends, poly-hydrocarbons containing oxygen, heavy hydrocarbon sludge and bottoms products from petroleum refineries and petrochemical plants such as hydrocarbon waxes, blends thereof, derivatives thereof, or any combination thereof.

The feedstock can include a mixture or combination of two or more low ash or no ash polymers, biomass derived materials, or by-products derived from manufacturing operations. For example, the feedstock can include one or more carbonaceous materials combined with one or more discarded consumer products, such as carpet and/or plastic automotive parts/components, e.g., bumpers or dashboards. As necessary, such discarded consumer products can be reduced in size, for example ground up, prior to or during processing through the gasification system 100. The feedstock can also include one or more recycled plastics such as polypropylene, polyethylene, polystyrene, derivatives thereof, blends thereof, or any combination thereof. Accordingly, the gasification system 100 can be useful for accommodating mandates for proper disposal of previously manufactured materials.

The feedstock can be dried and then pulverized by one or more milling units (not shown) prior to being introduced to the second lock hopper 130 via line 101. For example, the feedstock via line 101 can be dried from a high of about 35% moisture to a low of about 18% moisture. A fluid bed drier (not shown) can be used to dry the feedstock via line 101, for example.

The feedstock via line 101 can have an average particle size ranging from a low of about 1 micron, about 10 microns, about 50 microns, about 100 microns, about 150 microns, or about 200 microns to a high of about 1,350 microns, about 1,400 microns, about 1,450 microns, or about 1,500 microns. For example, the average particle size of the feedstock via line 101 can range from about 75 microns to about 1,475 microns, from about 125 microns to about 1,425 microns, or about 175 microns to about 1,375 microns. In another example, the feedstock via line 101 can be ground to have an average particle size of about 300 microns or less.

The gasifier feed system 140 can receive the sulfur containing carbonaceous material via line 131 to produce a first feed or “gasifier” feed via line 141. The gasifier feed system 140 can provide a controlled flow of the sulfur containing carbonaceous material or carbonaceous feed into the gasifier 150 via line 141, while simultaneously accommodating for pressure changes within the gasifier 150. The gasifier feed system 140 can include one or more lock vessels or storage bins, one or more dispensing vessels, and/or one or more feeders connected by one or more valves.

Alternatively, sulfur can be added via line 123 directly to the gasifier feed system 140, bypassing the second lock hopper 130. In another example, the sulfur via line 124 can be added to the gasifier feed in line 141 instead of adding sulfur via line 121 to the second lock hopper 130 or the gasifier feed system 140. In yet another example, the sulfur via line 124 can be added to the gasifier feed of line 141 in conjunction with adding sulfur via line 121 to the second lock hopper 130 and/or adding sulfur via line 123 to the gasifier feed system 140. Although not shown, sulfur added via line 124 can be pressurized to a pressure of the gasifier feed in line 141 and/or the pressure of the gasifier 150 prior to introduction to the gasifier feed in line 141 and/or the gasifier 150.

The gasifier feed via line 141 can have an average particle size of from a low of about 1 micron, about 10 microns, about 50 microns, about 100 microns, or about 150 microns to a high of about 400 microns, about 450 microns, or about 500 microns. For example, the gasifier feed via line 141 can have an average particle size ranging from about 75 microns to about 475 microns, about 125 microns to about 425 microns, or from about 250 microns to about 350 microns.

The gasifier feed via line 141 can be introduced to the one or more gasifiers 150 to produce a raw syngas stream via line 151. The gasifier 150 can gasify at least a portion of the gasifier feed introduced via line 141 to produce the raw syngas stream via line 151. The gasifier feed via line 141 can be a dry feed or can be conveyed to the gasifier 150 as a slurry or suspension. The gasifier feed or sulfur containing carbonaceous material in line 141 can have a sulfur concentration sufficient to produce a syngas via line 151 capable of reducing or preventing metal dusting in the downstream process equipment. For example, the sulfur concentration in the gasifier fed via line 141 can be an amount sufficient to produce a raw syngas via line 151 having a sulfur concentration of at least 0.1 percent by volume (vol %), at least 0.2 vol %, or at least 0.3 vol %. The sulfur concentration of the raw syngas in line 151 can vary depending, at least in part, on the amount of sulfur added to the second lock hopper 130, the gasifier feed system 140, and/or the gasifier feed via line 141. For example, the sulfur concentration of the raw syngas in line 151 can be about 0.01 vol % or more, 0.05 vol % or more, about 0.1 vol % or more, about 0.15 vol % or more, about 0.2 vol % or more, about 0.25 vol % or more, about 0.3 vol % or more, about 0.35 vol % or more, about 0.4 vol % or more, about 0.45 vol % or more, about 0.5 vol % or more, about 0.6 vol % or more, about 0.7 vol % or more, about 0.8 vol % or more, about 0.9 vol % or more, or about 1 vol % or more. In another example, the sulfur concentration of the raw syngas stream 151 can range from about 0.1 vol % to about 0.4 vol %. The sulfur can be present in the form of hydrogen sulfide, carbonyl sulfide, and other sulfur containing compounds.

The raw syngas in line 151 can also contain about 60 vol % or more carbon monoxide and hydrogen with additional components including primarily carbon dioxide and methane. For example, the raw syngas in line 151 can contain about 90 vol % or more carbon monoxide and hydrogen, about 95 vol % or more carbon monoxide and hydrogen, about 97 vol % or more carbon monoxide and hydrogen, or about 99 vol % or more carbon monoxide and hydrogen. In one example, the carbon monoxide content of the raw syngas in line 151 can range from a low of about 10 vol %, about 20 vol %, or about 30 vol % to a high of about 50 vol %, about 70 vol % or about 85 vol %. In another example, the carbon monoxide content of the raw syngas in line 151 can range from a low of about 15 vol %, about 25 vol %, or about 35 vol % to a high of about 65 vol %, about 75 vol % or about 85 vol %. The hydrogen content of the raw syngas in line 151 can range from a low of about 1 vol %, about 5 vol %, or about 10 vol % to a high of about 30 vol %, about 40 vol % or about 50 vol %. For example, the hydrogen content of the raw syngas in line 151 can range from about 20 vol % to about 30 vol %.

The raw syngas in line 151 can contain less than about 25 vol % or less, about 20 vol % or less, about 15 vol % or less, about 10 vol % or less, or about 5 vol % or less of combined nitrogen, methane, carbon dioxide, water, hydrogen sulfide, and hydrogen chloride. The carbon dioxide content of the raw syngas in line 151 can be about 25 vol % or less, about 20 vol % or less, about 15 vol % or less, about 10 vol % or less, about 5 vol % or less, about 3 vol % or less, about 2 vol % or less, or about 1 vol % or less. The methane content of the raw syngas in line 151 can be about 15 vol % or less, about 10 vol % or less, about 5 vol % or less, about 3 vol % or less, about 2 vol % or less, or about 1 vol % or less. The water content of the raw syngas in line 151 can be about 40 vol % or less, about 30 vol % or less, about 25 vol % or less, about 20 vol % or less, about 15 vol % or less, about 10 vol % or less, about 5 vol % or less, about 3 vol % or less, about 2 vol % or less, or about 1 vol % or less. The raw syngas in line 151 can be nitrogen-free or essentially nitrogen-free, e.g., containing about 0.5 vol % or less nitrogen.

The raw syngas in line 151 can have a heating value, corrected for heat losses and dilution effects, of about 1,863 kJ/m³ (50 Btu/scf) to about 2,794 kJ/m³ (75 Btu/scf); about 1,863 kJ/m³ to about 3,726 kJ/m³ (100 Btu/scf); about 1,863 kJ/m³ to about 4,098 kJ/m³ (110 Btu/scf); about 1,863 kJ/m³ to about 5,516 kJ/m³ (140 Btu/scf); about 1,863 kJ/m³ to about 6,707 kJ/³ (180 Btu/scf); about 1,863 kJ/m³ to about 7,452 kJ/m³ (200 Btu/scf); about 1,863 kJ/m³ to about 9,315 kJ/m³ (250 Btu/scf); about 1,863 kJ/m³ to about 10,246 kJ/m³ (275 Btu/sef), 1,863 kJ/m³ to about 11,178 kJ/m³ (300 Btu/scf), or about 1,863 kJ/m³ to about 14,904 kJ/m³ (400 Btu/scf).

One or more analyzers 160 can be used to control the rate and amount of sulfur to the gasifier 150. The analyzer 160 can be used to detect or measure the amount of sulfur and/or sulfur compounds, i.e., the sulfur content or concentration, in the raw syngas and can communicate with the feeder 120 and/or the first lock hopper 110 via a communication link 161 to control the rate and/or amount of sulfur added to the second lock hopper 130, the gasifier feed system 140, the gasifier feed in line 141, and/or directly injected into the gasifier 150 (not shown). The communication link 161 can be wired, wireless, or a combination thereof. In another example, the analyzer 160 can alert personnel of the sulfur concentration in the raw syngas in line 151 and the rate and/or amount of sulfur added to the second lock hopper 130, the gasifier feed system 140, the gasifier feed in line 141, and/or directly injected into the gasifier 150 (not shown) can be manually adjusted or controlled.

The analyzer 160 can be located downstream of the gasifier 150, e.g., past one or more coolers (not shown) and/or one or more particulate removal units (not shown) to allow for cooling of the syngas and/or removal of at least portion of the entrained solids prior to detecting or measuring the sulfur concentration in the syngas, respectively. For example, the analyzer 160 can measure the sulfur concentration of the syngas once it has been cooled to a temperature of about 600° C. or less, about 500° C. or less, about 450° C. or less, about 400° C. or less, about 350° C. or less, about 300° C. or less, about 250° C. or less, or about 200° C. or less. In another example, the analyzer 160 can measure the sulfur concentration of the syngas once it has been cooled to a temperature of less than 350° C. In yet another example, the analyzer 160 can measure the sulfur concentration of the syngas once the level of particulates in the syngas has been reduced to about 10 ppmw or less, about 5 ppmw or less, about 1 ppmw or less, about 0.3 ppmw or less, about 0.2 ppmw or less, or about 0.1 ppmw or less.

The analyzer 160 can be any analyzer or technique capable of estimating, detecting, or measuring an amount or concentration of sulfur or sulfur compounds in the syngas. For example, the analyzer 160 can use gas chromatography, vapor-phase chromatography, and/or gas-liquid partition chromatography to detect, measure, or otherwise estimate the sulfur concentration in the raw syngas stream 151 coming out of the gasifier 150. The analyzer 160 can use a flow-through narrow tube or column, through which different chemical constituents of a sample pass in a gas stream or carrier gas at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, referred to as a stationary phase. The passing of the carrier gas can be referred to as the moving or mobile phase. The moving phase can utilize a carrier gas including, but not limited to, an inert gas such as helium or an unreactive gas such as nitrogen. The analyzer 160 can also be or include a spectrometer, laser spectrometer, aerograph, gas separator, or any combinations of the foregoing analytical equipment or techniques.

Detectors that can be used in the analyzer 160 can include, but are not limited to, flame ionization detectors (FID), thermal conductivity detectors (TCD), discharge ionization detectors (DID), electron capture detectors (ECD), flame photometric detectors (FPD), flame ionization detectors (FID), Hall electrolytic conductivity detectors (HECD), helium ionization detectors (HID), nitrogen phosphorus detectors (NPD), infrared detectors (IRD), mass selective detectors (MSD), photo-ionization detectors (PID), pulsed discharge ionization detectors (PDD), thermal energy (conductivity) analyzer/detectors (TEA/TCD), mass spectrometers, infrared spectrophotometers, nuclear magnetic resonance (NMR) spectrometers, or a combination thereof.

In operation, the feeder 120 can be automatically and/or manually adjusted according to the signal and/or data conveyed in the communication link 161. The feeder 120 can be a metered feeder or a rotofeed dispenser, and can be driven by a variable speed electric motor (not shown) to adjust the feed rate and amounts of the sulfur. When the analyzer 160 detects an insufficient amount of sulfur and/or sulfur compounds in the raw syngas in line 151, i.e., the sulfur concentration is below a predetermined value or a desired first or “lower” threshold, the feeder 120 can be adjusted to increase the rate at which the sulfur via line 122 is dispensed or conveyed to the second lock hopper 130, the gasifier feed system 140, and/or the gasifier feed in line 141. An insufficient amount of sulfur in the raw syngas in line 151 refers to a sulfur concentration of less than about 0.1 vol %, based on the total volume of the raw syngas in line 151.

When the analyzer 160 detects an excess amount of sulfur and/or sulfur compounds in the raw syngas in line 151, i.e., the sulfur concentration or concentration is above a desired second or “upper” threshold, the feeder 120 can be automatically and/or manually adjusted to decrease the rate at which the sulfur via line 122 is dispensed or conveyed to the gasifier feed system 140, the rate at which the sulfur via line 123 is added to the gasifier feed system 140, and/or the rate at which the sulfur via line 124 is introduced to the gasifier 150 via line 141. For example, when the sulfur concentration in the raw syngas in line 151 increases above about 0.4 vol %, about 0.5 vol %, about 0.6 vol %, about 0.7 vol %, about 0.8 vol %, about 0.9 vol %, or about 1 vol %, the amount of sulfur introduced to the second lock hopper 130, the gasifier feed system 140, and/or the gasifier feed in line 141 can be reduced and/or stopped. In this way the sulfur concentration in the raw syngas stream 151 can be automatically or manually controlled to maintain the sulfur concentration within a predetermined or desired range to reduce or prevent metal dusting in components downstream of the gasifier 150.

Considering the gasifier 150 in more detail, the gasifier 150 can be or include one or more circulating solid or transport gasifiers, one or more fixed bed gasifiers, one or more fluidized bed gasifiers, one or more entrained flow gasifiers, or a combination thereof. For example, circulating solid gasifiers can operate by introducing one or more oxidants to a feed stream, e.g., the gasifier feed via line 141, and/or to one or more mixing zones (not shown) to provide a gas mixture. In another example, the oxidant can be added directly to the gasifier. The type and amount of oxidant introduced to circulating solid gasifiers can influence the composition and physical properties of the syngas via line 151 and hence, the downstream products made therefrom. The one or more oxidants can be introduced into the one or more mixing zones to produce a gas mixture, and, for example, can be introduced at a rate suitable to control the temperature of the mixing zone. The gas mixture can move upward through the mixing zone into a riser (not shown) where residence time can allow char gasification, methane/steam reforming, tar cracking, and/or water-gas shift reactions to occur. The temperature in the mixing zone can start at from about 500° C. to about 650° C. and increase to about 900° C., for example if a coke breeze or an equivalent is fed therein. In one example, the riser can operate at a higher temperature than the mixing zone. The gas mixture can exit the riser and enter one or more disengagers or cyclones (not shown) where large particulates can be separated from the gas and recycled back to the mixing zone.

The residence time within circulating solid gasifiers can be from about 2 seconds or more to about 10 seconds or more, where the temperature can be sufficient for water-gas shift reactions to reach equilibrium (i.e., temperatures ranging from a low of about 250° C. to a high of about 1,000° C.). The operating temperature of circulating solid gasifiers can be controlled, at least in part, by the recirculation rate and residence time of the solids within the riser, by reducing the temperature of the ash prior to recycle to the mixing zone, by the addition of steam to the mixing zone, and/or by the addition of oxidant to the mixing zone. Recirculated solids can serve to rapidly heat the incoming gasifier feed via line 141, which can minimize tar formation. The mixing zone can be operated at pressures of from about 100 kilopascals (kPa) to about 4500 kPa to increase thermal output per unit reactor cross-sectional area and enhance energy output in any subsequent power cycle.

Since the outlet temperature of a circulating solid gasifier can be proportionately less than comparable gasifiers (e.g., slag type), the amount of thermal heat versus chemical heat in the syngas can be comparably less in the circulating solid gasifier. Because of the reduced operating temperature within the gasifier (i.e., less than 1,600° C.), less energy can be consumed to control and optimize the H₂:CO ratio, thus the production of hydrogen can be increased without a commensurate increase in steam demand within the gasifier. Suitable circulating solid gasifiers can be as discussed and described in U.S. Pat. No. 7,722,690 and U.S. Patent Application Nos. 02008/0155899, 2009/0151250, and 2009/0188165.

In another example, fixed bed or moving bed gasifiers can operate by introducing the gasifier feed via line 141 into an upper or top part of a reactor (not shown). Oxygen and/or steam can be introduced to fixed bed gasifiers at a lower or bottom part of the reactor. The feed can move down through the reactor by gravity and can be gasified. Ash remaining from the gasification can drop out of the bottom part of the reactor. Fixed bed gasifiers can be operated at relatively low outlet temperature (425° C. to 700° C.) and can require a lesser amount of oxygen compared to fluidized bed gasifiers and entrained flow gasifiers, but can have a high demand for steam and produce significant amounts of tar. Fixed bed gasifiers can have a limited ability to handle fines and can have special requirements for handling caking coal. The product syngas from fixed bed gasifiers can contain unconverted methane and/or by-product tars and oils. Suitable fixed bed gasifiers can be as discussed and described in U.S. Pat. Nos. 4,290,780; 4,417,528; and 5,069,685 and U.S. Patent Application No. 2008/0086945.

In yet another example, fluidized bed gasifiers can operate by mixing solid particles from the gasifier feed via line 141 with older, partially gasified and/or fully gasified particles in a reactor (not shown). The solid particles can be fluidized with a gas and then the gas and remaining solid particles can be separated. Gas in the reactor can include oxygen, steam, recycled syngas, or a combination thereof. The flow of the gas into the reactor can be sufficient to float the solid particles without entraining them out of the reactor. Fluidized bed gasifiers can operate at moderate outlet temperatures and the temperature can be uniform throughout the bed. For example, fluidized bed gasifiers can operate at a temperature ranging from a low of about 700° C., about 750° C., about 800° C., or about 850° C. to a high of about 1,000° C., about 1,050° C., about 1,100° C., or about 1,150° C. Fluidized bed gasifier can require a greater amount of oxygen than comparable fixed bed gasifiers but less than comparable entrained flow gasifiers. Likewise, fluidized bed gasifier can require less steam than comparable fixed bed gasifiers but more than comparable entrained flow gasifiers. The syngas from fluidized bed gasifiers can be of higher purity than the syngas from comparable entrained flow gasifiers and the carbon conversion can be lower than comparable entrained flow gasifiers. Purity can be measured by the amount of H₂+CO in the syngas. For example, the purity of the syngas in a fluidized bed gasifier can range from 25% to 90% H₂+CO. The carbon conversion in a fluidized bed gasifier can range, for example, from a low of about 92%, about 93%, or about 94% to a high of about 97%, about 98%, or about 99%. Suitable fluidized bed gasifiers can be as discussed and described in U.S. Pat. Nos. 4,696,678; 6,972,114; and 7,503,945 and U.S. Patent Application No. 2008/0250714.

In still another example, entrained flow gasifiers can operate by injecting the gasifier feed via line 141 in co-concurrent flow with an oxidant into a reactor bed (not shown). The gasifier feed rapidly heats up and reacts with the oxidant. The oxidant can be oxygen, steam, recycled syngas, or a combination thereof. Entrained flow gasifiers can require a large amount of oxidant and can require high oxygen purity. For example, entrained flow gasifiers can require from about 0.2 normal cubic meters (“Nm³”) O₂ to about 0.5 Nm O₂ per Nm³ (H₂+CO). In addition, an oxidant introduced to an entrained flow gasifier can have a purity of about 99.5 vol % or more. Entrained flow gasifiers can operate at high temperatures, and often require a high temperature to achieve high carbon conversion. For example, entrained flow gasifiers can operate at a temperature ranging from a low of about 1,150° C., about 1,200° C., about 1,250° C., or about 1,300° C. to a high of about 1,550° C., about 1,600° C., about 1,650° C., or about 1,700° C. Entrained flow gasifiers can also require higher energy input than fixed bed gasifiers in the form of higher specific steam and/or oxygen consumption. Entrained flow gasifiers can obtain a high purity syngas and can gasify a large range of materials. For example, the syngas from an entrained flow gasifier can have less than about 0.5% N₂, no tars, and parts per million of methane. Entrained flow gasifiers can have short residence times, i.e., from a low of about 0.1 seconds, about 0.2 seconds, or about 0.3 seconds to a high of about 1 second, about 2 seconds, or about 3 seconds. Suitable entrained flow gasifiers can be as discussed and described in U.S. Pat. Nos. 4,158,552; 4,531,949; and 5,620,487 and U.S. Patent Application No. 2010/0088959.

FIG. 2 depicts a schematic of another illustrative gasification system 200 for producing a syngas via line 251 having a sulfur concentration sufficient to reduce metal dusting in components downstream of one or more gasifiers (one is shown 250), according to one or more embodiments. Similar to the embodiment discussed and described above with reference to FIG. 1, sulfur can be stored in one or more first lock hoppers or storage bins 110. The first lock hopper 110 can be in communication with a first or “sulfur” feeder 220 either directly or via line 111. The first feeder 220 can dispense the sulfur from the first lock hopper 110 via lines 221 and 222 to the one or more second lock hoppers 130. The first feeder 220 can control the amount and/or rate of sulfur dispensed via line 221 into the second lock hopper 130. For example, the first feeder 220 can be a metered feeder or a rotofeed dispenser, and can be driven by a variable speed electric motor (not shown). The sulfur can be pulverized or ground prior to being fed to the first lock hopper 110 and/or the first feeder 220, and can have an average particle size after being pulverized to the dimensions discussed and described above with reference to the first lock hopper 110 and the feeder 120 in FIG. 1.

The second lock hopper 130 can receive, store, and/or mix the feedstock via line 101 and the sulfur via line 222 and can convey or dispense a sulfur containing carbonaceous material via line 239 to the gasifier feed system 240. Alternatively, sulfur can be added directly to the gasifier feed system 240, bypassing the second lock hopper 130. For example, sulfur via line 223 can be added to one or more storage bins 242 of the gasifier feed system 240 in lieu of adding sulfur via lines 221 and 222 to the second lock hopper 130.

The second lock hopper 130 can operate via line 231 in conjunction with a second feeder 234, such as a high pressure rotary feeder that cooperates with an added fluid stream (not shown) to convey the carbonaceous material via line 239 to the gasifier feed system 240. Illustrative fluids can include, but are not limited to, air, nitrogen, carbon dioxide, or any combination thereof. Preferably, the carbonaceous material can be conveyed from the second lock hopper 130 to the gasifier feed system 240 at a rate of at least 10,000 kg/hr, and more preferably at a rate between about 20,000 kg/hr and a high of about 30,000 kg/hr.

The gasifier feed system 240 can receive the sulfur containing carbonaceous material via line 239 and/or from another process or source (not shown) and produce a gasifier feed via line 241. The gasifier feed system 240 can include the storage bin 242, one or more first or “lock” vessels 244, one or more second or “dispensing” vessels 246, and one or more second feeders 248. The storage bin 242 can be joined to and/or in fluid communication with the lock vessel 244 by one or more first control valves 243, and the storage bin 244 can be joined to and/or in fluid communication with the dispensing vessel 246 by one or more second control valves 245.

The carbonaceous material from the second lock hopper 130 via line 239 and any additional sulfur via line 223 can be introduced to the storage bin 242. Nitrogen via a low pressure nitrogen source 202 can be added to the storage bin 242 to maintain atmospheric pressure within the storage bin 242. Sulfur added to the storage bin 242 can mix with the carbonaceous material in the storage bin 242 to provide a sulfur containing carbonaceous material in the lock vessel 244 and/or the dispensing vessel 246.

The carbonaceous material via line 239 can be with or without sulfur added and can be dried and/or pulverized. For example, the carbonaceous material via line 101 can be dried and pulverized by one or more milling units (not shown) prior to being fed to the second lock hopper 130. For example, the feedstock via line 101 can be dried to about 22% to about 15% moisture. In another example, the feedstock via line 101 can be dried to about 18% moisture. In one or more embodiments, a fluid bed drier (not shown) can be used to dry the feedstock via line 101. The carbonaceous material via line 239 can be dried and pulverized by one or more milling units (not shown) prior to being fed to the storage bin 242. The milling unit can include, for example, one or more bowl mills or one or more rod mills (not shown).

Sulfur containing carbonaceous material from the storage bin 242 can be fed into the lock vessel 244 at a controlled rate or intermittently. The lock vessel 244 can be isolated from the storage bin 242 by closing the first control valve 243. The lock vessel 244 can be pressurized to a first or “full system” pressure with nitrogen via a first high pressure nitrogen source 203.

The first pressure in the lock vessel 244 can range from a low of about 2,400 kPa, about 2,600 kPa, about 2,800 kPa, or about 3,000 kPa to a high of about 4,000 kPa, about 4,200 kPa, about 4,400 kPa, or about 4,600 kPa. For example, the first pressure in the lock vessel 244 can range from about 2,500 kPa to about 4,500 kPa, from about 2,700 kPa to about 4,300 kPa, or from about 2,900 kPa to about 4,100 kPa. In another example, the first pressure can be about 3,500 kPa. The dispensing vessel 246 can remain at the first pressure.

Once the sulfur containing carbonaceous material in the lock vessel 244 has reached the first pressure, i.e., the pressure of the dispensing vessel 246, the second control valve 245 between the lock vessel 244 and the dispensing vessel 246 can be opened. The sulfur containing carbonaceous material can then feed into the dispensing vessel 246 by gravity until the full inventory of the lock vessel 244 is discharged into the dispensing vessel 246. The lock vessel 244 can then be isolated from the dispensing vessel 246 and depressurized in preparation for receiving another charge of sulfur containing carbonaceous material from the storage bin 242.

The dispensing vessel 246 can operate continuously at the first pressure. Pressure in the dispensing vessel 246 can be maintained with nitrogen via a second high pressure nitrogen source 204. The sulfur containing carbonaceous material can be transported from the bottom of the dispensing vessel 246 into one or more gasifiers 250 through the second feeder 248.

The second feeder 248 can be a non-mechanical feed control device with no moving parts and can combine continuous ash depressurization systems with traditional designs for flow rate control. The driving force for the flow of the sulfur containing carbonaceous material in the feeder 248 can be differential pressure therein. Nitrogen gas via a third high pressure nitrogen source 205 and transport fluid, e.g., air and/or recycled syngas, via a transport fluid source 206 can meter the flow of the sulfur containing carbonaceous material through and out of the feeder 248 into the gasifier 250.

The gasifier feed via line 241 can be introduced to the gasifier 250 to produce a raw syngas stream 251. The gasifier feed in line 241 can be a dry feed or can be conveyed to the gasifier 250 as a slurry or suspension. The gasifier 250 can be, but is not limited to, one or more circulating solid gasifiers, one or more fixed bed gasifiers, one or more fluidized bed gasifiers, one or more entrained flow gasifiers, or a combination thereof.

The gasifier 250 can include a single reactor train or two or more reactor trains arranged in series or parallel. Each reactor train can include one or more mixing zones 252, one or more risers 253, and one or more disengagers 254. Each reactor train can be configured independent from the others or configured where any of the one or more mixing zones 252, risers 253, or disengagers 254 can be shared. For simplicity and ease of description, embodiments of the gasifier 250 will be further described in the context of a single reactor train.

The gasifier feed via line 241 and one or more oxidants or process air via line 214 can be combined in the mixing zone 252 to provide a gas mixture or suspension. The gasifier feed via line 241 and oxidant via line 214 can be injected separately, as shown, to the mixing zone 252 or mixed prior to injection into the mixing zone (not shown). For example, the gasifier feed via line 241 and oxidant via line 214 can be injected sequentially into the gasifier 250. In another example, the gasifier feed via line 241 and oxidant via line 214 can be injected simultaneously into the gasifier 250.

The type and amount of oxidant introduced via line 214 to gasifier 250 can influence the composition and physical properties of the syngas via line 251 and hence, the downstream products made therefrom. The one or more oxidants can include, but are not limited to, air, oxygen, essentially oxygen, oxygen-enriched air, mixtures of oxygen and air, mixtures of oxygen and inert gas such as nitrogen and argon, and the like. The oxidant can contain about 65 vol % oxygen or more, about 70 vol % oxygen or more, about 75 vol % oxygen or more, about 80 vol % oxygen or more, about 85 vol % oxygen or more, about 90 vol % oxygen or more, about 95 vol % oxygen or more, or about 99 vol % oxygen or more. As used herein, the term “essentially oxygen” refers to an oxygen stream containing 51 vol % oxygen or more. As used herein, the term “oxygen-enriched air” refers to air containing 21 vol % oxygen or more. Oxygen-enriched air can be obtained, for example, from cryogenic distillation of air, pressure swing adsorption, membrane separation, or any combination thereof. At least one of the oxidants can be pure oxygen supplied from one or more air separation units (not shown). The one or more oxidants can be nitrogen-free or essentially nitrogen-free. By “essentially nitrogen-free,” it is meant that the one or more oxidants contain about 5 vol % nitrogen or less, about 4 vol % nitrogen or less, about 3 vol % nitrogen or less, about 2 vol % nitrogen or less, or about 1 vol % nitrogen or less.

The gas mixture can move upward through the mixing zone 252 into the riser 253 where additional residence time allows the char gasification, methane/steam reforming, tar cracking, and/or water-gas shift reactions to occur. The riser 253 can operate at a higher temperature than the mixing zone 252, and can have a smaller diameter than the mixing zone 252. Suitable temperatures in the riser 253 can range from a low of about 700° C., about 715° C., about 730° C., or about 750° C. to a high of about 950° C., about 1,000° C., about 1,050° C., or about 1,100° C. For example, suitable temperatures in the riser 253 can range from about 710° C. to about 1,075° C., about 720° C. to about 1,025° C., or about 740° C. to about 975° C. The superficial gas velocity in the riser 253 can range from a low of about 3 meters per second (m/s), about 6 m/s, or about 9 m/s to a high of about 21 m/s, about 24 m/s, or about 27 m/s. For example, the superficial gas velocity in the riser 253 can range from about 5 m/s to about 25 m/s, from about 10 m/s to about 18 m/s, or from about 9 m/s to about 12 m/s.

The gas mixture can exit the riser 253 and enter the disengagers 254 where larger particulates can be separated from the gas and recycled back to the mixing zone 252 via one or more conduits, including, but not limited to, a standpipe 259, and/or j-leg 258. The j-leg 258 can include a non-mechanical “j-valve” to increase the effective solids residence time, increase the carbon conversion, and minimize aeration requirements for recycling solids to the mixing zone 252. In one or more embodiments, the disengagers 254 can be cyclones. One or more particulate transfer devices 257, such as one or more loop seals or seal legs, can be located downstream of the disengagers 254 to collect separated particulate fines. Although not shown, a second stage solids separator or cyclone can be disposed or located on the standpipe 259 to separate out a majority of fines solids coming from a top of the disengagers 254. Any entrained or residual particulates in the raw syngas stream 251 can be removed using the one or more particulate removal systems or particulate control devices 290. Recycle gas via line 208, e.g., from a compressor (not shown), can be added to the j-leg 258, the particulate transfer device 257, the standpipe 259, or any combination thereof, for aeration to aid in solids circulation.

The one or more oxidants via line 214 can be introduced at the bottom of the mixing zone 252 to increase the temperature within the mixing zone 252 and riser 253 and combust any carbon contained within the recirculated particulates in the form an ash (“char”). For example, the one or more oxidants can be introduced into the mixing zone 252 at a rate suitable to control the temperature of the mixing zone 252. The one or more oxidants can include excess air. For example, the one or more oxidants can be sub-stoichiometric air wherein the molar ratio of oxygen to carbon can be maintained at a sub-stoichiometric concentration to favor the formation of carbon monoxide over carbon dioxide in the mixing zone 252. In another example, the oxygen supplied via the oxidant to the mixing zone 252 can be less than five percent of the stoichiometric amount of oxygen required for complete combustion of all the carbon supplied to the mixing zone 252. Additional oxygen and steam in the air can be consumed by the char in the recirculating solids, thereby stabilizing reactor temperature during operation and during periods of feed interruption.

The residence time and temperature in the gasifier 250 can be sufficient for water-gas shift reaction to reach equilibrium. For example, the residence time of the gasifier feed via line 241 in the mixing zone 252 can be greater than about 2 seconds, greater than about 5 seconds, or greater than about 10 seconds. The operating temperature of the gasifier 250 can range from a low of about 600° C., about 650° C., or about 700° C. to a high of. about 900° C., about 1,000° C., or about 1,100° C. For example, the operating temperature of the gasifier 250 can range from about 625° C. to about 1,050° C., from about 675° C. to about 1,025° C., or from about 700° C. to about 975° C.

The gasifier 250 can be operated in a temperature range sufficient to not melt the ash, such as from about 565° C. to about 1040° C. or from about 840° C. to about 930° C. Heat can be supplied by burning the carbon in the recirculated solids in the lower part of the mixing zone 252 before recirculated solids contact the entering gasifier feed via line 241. Startup can be initiated by bringing the mixing zone 252 to a temperature from about 500° C. to about 650° C. and optionally by feeding coke breeze or other solid, liquid, or gaseous fluid to the mixing zone 252 to further increase the temperature of the mixing zone 252 to about 900° C.

A startup burner 215 can be used to start the gasifier 250 via line 216. Fuel for the startup burner 215 can be supplied via a startup fuel line via line 233. Oxidant or process air for the startup burner 215 can be supplied via line 214. The startup burner 215 can be a direct propane-fired burner operated to heat the gasifier 250 to a temperature from about 500° C. to about 650° C. Liquid fuels, such as diesel, can also be used, based on their availability. The startup burner 215 can be started at a system pressure of ranging from about 500 kPa to about 550 kPa, and can operate at pressures ranging from about 950 kPa to about 1,050 kPa.

Temperature variations in the gasifier 250 can be dampened by large amounts of solids circulating in the gasifier 250. The circulating solids also can serve to rapidly heat the incoming gasifier feed via line 241 which can minimize tar formation.

The mixing zone 252 can be operated at pressures of from about 100 kPa to about 4500 kPa to increase thermal output per unit reactor cross-sectional area and enhance energy output in any subsequent power cycle. For example, the mixing zone 252 can be operated at pressures or from about 250 kPa to about 4000 kPa, from about 500 kPa to about 3000 kPa, or from about 750 kPa to about 2500 kPa.

The raw syngas in line 251 produced in the gasifier 250 can be similar to the raw syngas in line 151 discussed and described above with reference to FIG. 1. Steam can be added with the oxidant stream via line 214 to the mixing zone of the gasifier to moderate temperature rise at a point of introduction of the oxidant. Steam can also be supplied to the mixing zone of the gasifier 250 to control hydrogen to carbon monoxide ratios (H₂:CO) within the gasifier 250. Since the outlet temperature of the gasifier 250 can be proportionately less than comparable gasifiers (e.g., slag type), the amount of thermal heat versus chemical heat in the raw syngas via line 251 can be comparably less in the gasifier 250. Steam can be used to adjust by shift the H₂:CO ratio with a smaller energy penalty than other entrained flow gasifiers operating at higher temperatures. Because of the reduced operating temperature within the gasifier 250 (i.e., less than 1,600° C.), less energy can be consumed to control and optimize the H₂:CO ratio, thus the production of hydrogen can be increased without a commensurate increase in steam demand within the gasifier 250. The raw syngas via line 251 leaving the gasifier 250 can have a H₂:CO of ranging from about 0.6:1 to about 1.3:1. For example, the H₂:CO ratio can be about 0.7:1 to about 1.2:1, about 0.8:1 to about 1.1:1, or about 0.9:1 to about 1:1.

A gasifier bottoms drain pot 255 can be used to de-inventory ash from the gasifier 250 during turnarounds. Other accumulated ash in the standpipe 259 can be withdrawn from a particulate transfer device, e.g., a seal leg to maintain an ash level within the standpipe 259. Solids from the gasifier bottoms drain pot 255 can be fed to storage and/or be disposed of via line 256.

The raw syngas in line 251 can exit the gasifier at a temperature of from about 575° C. to about 1,050° C. The raw syngas in line 251 can be cooled using one or more coolers 270 (“primary coolers”) to provide a cooled raw syngas stream 286 prior to entry into the particulate removal system 290.

The cooler 270 can include one or more heat exchangers or heat exchanging zones (three are shown 271, 280, and 285) arranged in series. The raw syngas in line 251 can be cooled by indirect heat exchange in the first heat exchanger (“first zone”) 271 to a temperature of from about 260° C. to about 820° C. The cooled raw syngas exiting the first heat exchanger 271 via line 272 can be further cooled by indirect heat exchange in the second heat exchanger (“second zone”) 280 to a temperature of from about 260° C. to about 705° C. The cooled raw syngas exiting the second heat exchanger 280 via line 282 can be further cooled by indirect heat exchange in the third heat exchanger (“third zone”) 285 to a temperature of from about 260° C. to about 430° C.

The raw syngas in line 251 can be cooled using a heat transfer medium. The heat transfer medium can be saturated steam, boiler feed water, or the like. The heat transfer medium via line 283 can be introduced to the syngas cooler 270. Heat from the raw syngas can be indirectly transferred to the heat transfer medium to provide superheated or high pressure superheated steam that can be recovered via line 281. The superheated or high pressure superheated steam via line 281 can be used to power one or more steam turbines (not shown) that can drive a directly coupled electric generator (not shown), for example. Condensate recovered from the steam turbines can be recycled as boiler feed water to cool the syngas and produce steam.

The heat transfer medium via line 283 can be heated within the third heat exchanger (“economizer”) 285 to provide the cooled syngas via line 286 and a boiler feed water via line 287. The boiler feed water via line 287 can be saturated or substantially saturated at the process conditions. The boiler feed water via line 287 can be introduced (“flashed”) to one or more steam drums or separators 275 to provide a heated water via line 277 to feed into the steam generator 271.

The superheated or high pressure superheated steam via line 281 from the syngas cooler 270 can have a temperature of about 400° C. or more, 425° C. or more, 450° C. or more, 475° C. or more, 500° C. or more, or 550° C. or more. The superheated or high pressure superheated steam via line 281 can have a pressure of about 4,000 kPa or more, about 4,500 kPa or more, about 5,000 kPa or more, about 5,550 kPa or more, about 6,000 kPa or more, about 6,500 kPa or more, about 7,000 kPa or more, or about 7,500 kPa or more.

Boiler feed water via line 277 from the separator 275 can be introduced to the first heat exchanger (“steam generator”) 271 and heated against raw syngas in line 251 thereby producing steam which can be introduced to the separator 275 via line 273. The steam returned to the separator 275 via line 273 can exit via line 276 for superheating in the second heat exchanger 280 to provide superheated or high pressure superheated steam via line 281 for use in the one or more steam turbines (not shown). Solids buildup in the separator 275 can be controlled by blowing down a small amount of water via line 278.

Any one or all of the heat exchangers 271, 280, 285 (three are shown) can be shell-and-tube type heat exchangers. The raw syngas in line 251 can be supplied in series to the shell-side or tube-side of the first heat exchanger 271, second heat exchanger 280, and third heat exchanger 285. The heat transfer medium can pass through either the shell-side or tube-side, depending on which side the raw syngas is introduced. In one or more embodiments, the raw syngas in line 251 can be supplied in parallel (not shown) to shell-side or tube-side of the first heat exchanger 271, second heat exchanger 280, and third heat exchanger 285 and the heat transfer medium can pass serially through either the shell-side or tube-side, depending on which side the raw syngas is introduced. Make-up heat transfer medium can be added via line 283.

The cooled syngas via line 286 can be introduced to the particulate removal system 290 to partially or completely remove particulates from the cooled syngas to provide a separated, “particulate-lean,” or “clean” syngas via line 291, separated particulates via line 292, and condensate via line 293. During startup, steam via line 288 can be supplied to the particulate removal system 290 to preheat it. Although not shown, the one or more particulate removal systems 290 can optionally be used to partially or completely remove particulates from the raw syngas in line 251 before cooling. For example, the raw syngas in line 251 can be introduced directly to the particulate removal system 290, resulting in hot gas particulate removal (e.g., from about 550° C. to about 1,050° C.). Although not shown, two particulate removal systems 290 can be used. For example, one particulate removal system 290 can be upstream of the cooler 270 and one particulate removal system 290 can be downstream of the cooler 270.

The one or more particulate removal systems 290 can include one or more separation devices such as conventional disengagers and/or cyclones (not shown). Particulate control devices (“PCD”) capable of providing an outlet particulate concentration below the detectable limit of about 0.1 ppmw can also be used. Illustrative PCDs can include, but are not limited to, sintered metal filters, metal filter candles, and/or ceramic filter candles (for example, iron aluminide filter material). A small amount of high-pressure recycled syngas via line 289 can be used to pulse-clean filters as they accumulate particles from the unfiltered syngas.

One or more analyzers (two are shown 260, 265) can be placed downstream of the gasifier 250 to detect the amount of sulfur or sulfur concentration coming out of the gasifier 250. The analyzers 260, 265 can communicate with the first feeder 220 and/or the first lock hopper 110 via communication links 261, 266, and/or 267 to facilitate control of and/or maintenance of the sulfur concentration in the gasifier 250 and/or in the raw syngas stream 251. The communication links 261, 266, and/or 267 can be wired, wireless, or a combination thereof.

The sulfur concentration can be measured by the analyzers 260, 265 downstream of the gasifier 250 at a point where the temperature is cool enough to be sent to a tempering system (not shown) but upstream of any treatment systems that would change the sulfur concentration of the syngas, such as caustic wash step. For example, the first analyzer 260 can measure the sulfur concentration in the cooled syngas via line 286 after it has been cooled by the cooler 270. In another example, the second analyzer 265 can measure the sulfur concentration in the separated syngas via line 291 after it has passed through the particulate removal system 290. In yet another example, the first analyzer 260 can measure the sulfur concentration in the cooled syngas via line 286 and the second analyzer 265 can measure the sulfur concentration in the separated syngas via line 291. The analyzers 260, 265 can be, but are not limited to, gas chromatographs, aerographs, gas separators, or any combination thereof. The analyzers 260, 265 can be the same or similar to the analyzer 160 discussed and described above with reference to FIG. 1.

Once the analyzers 260, 265 measure or determine the sulfur concentration in the cooled syngas via line 286 and/or the separated syngas via line 291, the analyzers 260, 265 can output a signal and/or data via the communication links 261, 266, and/or 267 to an operator (not shown), the first feeder 220, and/or the first lock hopper 110. For example, the first analyzer 260 can communicate via communication links 261 and 267 to the first feeder 220 and/or the first lock hopper 110. In another example, the second analyzer 265 can communicate via communication links 266 and 267 to the first feeder 220 and/or the first lock hopper 110. In yet another example, the analyzers 260, 265 can both communicate information to the feeder via the communication links 261, 266, and/or 267. Although not shown, communication and actuation of the first feeder 220 and/or the first lock hopper 110 can be facilitated by an operator and/or a control unit that can be local or remote to the system 200.

In operation, the first feeder 220 can be adjusted according to the signal and/or data conveyed in the communication link 267. When the first analyzer 260 and/or second analyzer 265 detect an insufficient amount of sulfur in the cooled syngas via line 286 and/or the separated syngas via line 291, i.e., the sulfur concentration is lower than desired, the first feeder 220 can be adjusted to increase the rate at which the sulfur via line 222 is dispensed or conveyed to the gasifier feed system 240 and/or the rate at which the sulfur via line 223 is dispensed to the storage bin 242 of the gasifier feed system 240. An insufficient amount of sulfur in the cooled syngas via line 286 can be defined as a sulfur concentration of less than about 0.05 vol %, about 0.1 vol %, or about 0.2 vol %, based on the total volume of the cooled syngas in line 286. An insufficient amount of sulfur in the separated syngas via line 291 can be defined as a sulfur concentration of less than about 0.05 vol %, about 0.1 vol %, or about 0.2 vol %, based on the total volume of the separated syngas in line 291.

When the analyzers 260, 265 detect an excess amount of sulfur in the cooled syngas via line 286 and/or the separated syngas via line 291, i.e., the sulfur concentration is too high, the first feeder 220 can be adjusted to decrease the rate at which the sulfur via line 222 is dispensed or conveyed to the lock hopper 130 and/or the rate at which the sulfur via line 223 is dispensed to the storage bin 242 of the gasifier feed system 240. For example, when the sulfur concentration in the cooled syngas via line 286 increase above about 0.3 vol %, about 0.4 vol %, or about 0.5 vol %, about 0.6 vol %, about 0.7 vol %, about 0.8 vol %, about 0.9 vol %, or about 1 vol %, the amount of sulfur dispensed to the locker hopper 130 and/or the gasifier feed system 240 can be reduced or stopped. In another example, when the sulfur concentration in the separated syngas via line 291 increases above about 0.3 vol %, about 0.4 vol %, or about 0.5 vol %, about 0.6 vol %, about 0.7 vol %, about 0.8 vol %, about 0.9 vol %, or about 1 vol %, the amount of sulfur dispensed to the locker hopper 130 and/or the gasifier feed system 240 can be reduced or stopped.

All adjustments to the first feeder 220 based on the sulfur concentration(s) detected by the analyzers 260, 265 can be automatic adjustments. In another example, the adjustments can be actuated by a controller (not shown) that receives one or more signals and/or data from the analyzers 260, 265 via the communication links 261, 266, 267 or other communication links (not shown). The amount of sulfur dispensed by the first feeder 220 can also be adjusted manually based on the signals and/or data sent by the analyzers 260, 265.

Embodiments of the present disclosure further relate to any one or more of the following paragraphs:

1. A method for maintaining a sulfur concentration in a syngas, comprising combining sulfur and a carbonaceous material to produce a sulfur containing carbonaceous feed; gasifying at least a portion of the sulfur concentration in the syngas; and adjusting an amount of sulfur added to the carbonaceous material based on the detected sulfur concentration.

2. The method of paragraph 1, wherein the carbonaceous material comprises coal, coke, petroleum, biomass, or any combination thereof.

3. The method of paragraph 1 or 2, wherein the syngas has a desired sulfur concentration of at least 0.1 vol %.

4. The method according to any one of paragraphs 1 to 3, wherein the carbonaceous material has an average particle size of about 50 microns to about 500 microns.

5. The method of paragraph 4, wherein the added sulfur has an average particle size of from about 50 microns to about 500 microns.

6. The method according to any one of paragraphs 1 to 5, wherein the sulfur is detected using gas chromatography, spectrometry, vapor-phase chromatography, gas-liquid partition chromatography, or a combination thereof.

7. The method of paragraph 6, wherein the sulfur containing carbonaceous mixture has an average particle size of about 400 microns or less.

8. The method according to any one of paragraphs 1 to 7, wherein the sulfur containing carbonaceous feed is gasified in a transport gasifier.

9. The method according to any one of paragraphs 1 to 7, wherein the sulfur containing carbonaceous feed is gasified in a fluidized bed gasifier.

10. The method according to any one of paragraphs 1 to 7, wherein the sulfur containing carbonaceous feed is gasified in an entrained flow gasifier.

11. The method according to any one of paragraphs 1 to 7, wherein the sulfur containing carbonaceous feed is gasified in a fixed bed gasifier.

12. A method for maintaining sulfur concentration in syngas, comprising adding sulfur to a carbonaceous material to produce a sulfur containing carbonaceous containing at least 0.05 vol % sulfur; introducing the sulfur containing carbonaceous feed to a transport gasifier to produce a syngas; detecting a sulfur concentration in the syngas; and adjusting an amount of sulfur added to the carbonaceous material based on the detected sulfur concentration to maintain the sulfur concentration in the syngas at about 0.1 vol % or more.

13. The method of paragraph 12, further comprising increasing the amount of sulfur added to the carbonaceous material when the sulfur concentration in the syngas is below 0.1 vol %.

14. The method of paragraph 12 or 13, further comprising decreasing the amount of sulfur added to the carbonaceous material when the sulfur concentration in the syngas is above about 0.4 vol %.

15. A method for maintaining sulfur concentration in syngas, comprising adding sulfur at a controlled rate to a carbonaceous material to produce a sulfur containing carbonaceous mixture, wherein a first feeder adjusts the controlled rate of the sulfur; introducing the sulfur containing carbonaceous mixture to a feed system to produce a sulfur containing carbonaceous feed; introducing the sulfur containing carbonaceous feed to a gasifier operated at conditions sufficient to produce a syngas having a sulfur concentration of about 0.1 vol % to about 0.4 vol %; detecting a sulfur concentration in the syngas; adjusting the first feeder to increase the rate sulfur is added to the carbonaceous material when the sulfur concentration is below 0.1 vol %; and adjusting the first feeder to decrease the rate sulfur is added to the carbonaceous material when the sulfur concentration is above 0.4 vol %.

16. The method of paragraph 15, further comprising changing the pressure of the sulfur containing carbonaceous material from atmospheric pressure to a gasifer operating pressure.

17. The method of paragraph 15 or 16, wherein the gasifier operates at temperatures ranging from about 700 C to 1,000 C.

18. The method according to any one of paragraphs 15 to 17, further comprising introducing the syngas to one or more coolers to produce a cooled syngas, wherein the sulfur concentration of the syngas is detected after the syngas has been cooled.

19. The method of claim 18, further comprising introducing the cooled syngas to a particulate control device to partially or completely remove particulates from the cooled syngas to produce a particulate-lean syngas and separated particulates; detecting a sulfur concentration in the particulate-lean syngas with a second analyzer; adjusting the metered feeder to increase the rate sulfur is added to the carbonaceous material when the sulfur concentration of the particulate-lean syngas is below the first threshold; and adjusting the metered feeder to decrease the rate sulfur is added to the carbonaceous material when the sulfur concentration of the particulate-lean syngas the above a second threshold.

20. The method according to any one of paragraphs 15 to 19, wherein the gasifier operates at a pressure ranging from about 750 kPa to about 2,500 kPa.

Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges from any lower limit to any upper limit are contemplated unless otherwise indicated. Certain lower limits, upper limits, and ranges appear in one or more claims below. All numerical values are “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A method for maintaining a sulfur concentration in a syngas, comprising:

combining sulfur and a carbonaceous material to produce a sulfur containing carbonaceous feed;

gasifying at least a portion of the sulfur containing carbonaceous feed to produce a syngas;

detecting a sulfur concentration in the syngas; and

adjusting an amount of the sulfur combined with the carbonaceous material based on the detected sulfur concentration.

2. The method of claim 1, wherein the carbonaceous material comprises coal, coke, petroleum, biomass, or any combination thereof.

3. The method of claim 1, wherein the syngas has a sulfur concentration of at least 0.1 vol %.

4. The method of claim 1, wherein the carbonaceous material has an average particle size of about 50 microns to about 500 microns.

5. The method of claim 4, wherein the sulfur has an average particle size of from about 50 microns to about 500 microns.

6. The method of claim 1, wherein the sulfur is detected using gas chromatography, spectrometry, vapor-phase chromatography, gas-liquid partition chromatography, or any combination thereof.

7. The method of claim 6, wherein the sulfur containing carbonaceous mixture has an average particle size of about 400 microns or less.

8. The method of claim 1, wherein the sulfur containing carbonaceous feed is gasified in a transport gasifier.

9. The method of claim 1, wherein sulfur containing carbonaceous feed is gasified in a fluidized bed gasifier.

10. The method of claim 1, wherein the sulfur containing carbonaceous feed is gasified in an entrained flow gasifier.

11. The method of claim 1, wherein the sulfur containing carbonaceous feed is gasified in a fixed bed gasifier.

12. A method for maintaining sulfur concentration in syngas, comprising:

adding sulfur to a carbonaceous material to produce a sulfur containing carbonaceous feed containing at least 0.05 vol % sulfur;

introducing the sulfur containing carbonaceous feed to a transport gasifier to produce a syngas;

detecting a sulfur concentration in the syngas; and

adjusting an amount of sulfur added to the carbonaceous material based on the detected sulfur concentration to maintain the sulfur concentration in the syngas at about 0.1 vol % or more.

13. The method of claim 12, further comprising increasing the amount of sulfur added to the carbonaceous material when the sulfur concentration in the syngas is below 0.1 vol %.

14. The method of claim 12, further comprising decreasing the amount of sulfur added to the carbonaceous material when the sulfur concentration in the syngas is above about 0.4 vol %.

15. A method for maintaining sulfur concentration in syngas, comprising:

adding sulfur at a controlled rate to a carbonaceous material to produce a sulfur containing carbonaceous mixture, wherein a first feeder adjusts the controlled rate of the sulfur;

introducing the sulfur containing carbonaceous mixture to a feed system to produce a sulfur containing carbonaceous feed;

introducing the sulfur containing carbonaceous feed to a gasifier operated at conditions sufficient to produce a syngas;

detecting a sulfur concentration in the syngas;

adjusting the first feeder to increase the rate sulfur is added to the carbonaceous material when the sulfur concentration is below 0.1 vol %; and

adjusting the first feeder to decrease the rate sulfur is added to the carbonaceous material when the sulfur concentration is above 0.4 vol %.

16. The method of claim 15, further comprising changing the pressure of the sulfur containing carbonaceous material from atmospheric pressure to a gasifer operating pressure.

17. The method of claim 15, wherein the gasifier operates at temperatures ranging from about 700 C to 1,000 C.

18. The method of claim 15, further comprising introducing the syngas to one or more coolers to produce a cooled syngas, wherein the sulfur concentration in the syngas is detected after the syngas has been cooled.

19. The method of claim 18, further comprising:

introducing the cooled syngas to a particulate control device to partially or completely remove particulates from the cooled syngas to produce a particulate-lean syngas and separated particulates;

detecting a sulfur concentration in the particulate-lean syngas with a second analyzer;

adjusting the metered feeder to increase the rate sulfur is added to the carbonaceous material when the sulfur concentration of the particulate-lean syngas is below a first threshold; and

adjusting the metered feeder to decrease the rate sulfur is added to the carbonaceous material when the sulfur concentration of the particulate-lean syngas the above a second threshold.

20. The method of claim 15, wherein the gasifier operates at a pressure ranging from about 750 kPa to about 2,500 kPa.