Process and system for water-gas shift conversion of high CO concentration syngas

Abstract

A method for concentrating hydrogen in a synthesis gas is presented. The method includes adding HO to the synthesis gas to form a synthesis gas stream containing hydrogen, carbon monoxide, and steam. The synthesis gas stream has a steam-to-dry gas molar ratio S / DG and an oxygen-to-carbon molar ratio O / C. The method includes introducing the synthesis gas stream into a water-gas shift reactor and reacting the synthesis gas stream in the water-gas shift reactor in the presence of a non-iron-based catalyst to produce a shifted synthesis gas. The method further includes controlling the outlet temperature of the synthesis gas stream to remain below or decrease below a critical temperature by adjusting the S / DG ratio to maintain the O / C ratio below a lower O / C limit or above an upper O / C limit.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-Provisional Application No. 17 / 960,854, filed October 6, 2022, which is incorporated by reference herein in its entirety.

[0002] The present invention relates generally to the conversion of carbon monoxide and steam in syngas to a hydrogen-enriched shifted syngas, and more particularly to the conversion of syngas containing high levels of carbon monoxide in a high temperature water gas shift reaction. The synthesis gas feed to the water gas shift reaction can contain greater than 15% carbon monoxide by volume on a dry basis. [Background technology]

[0003] Historically, high-temperature shift (HTS) reactors have used catalysts made from iron oxide and chromium oxide. To avoid over-reduction of the iron in these catalysts, a minimum steam-to-dry gas (S / DG) ratio is required based on a given syngas composition. The higher the syngas reduction potential, the higher the minimum steam requirement, and vice versa. The minimum steam required to avoid over-reduction of iron-based HTS catalysts is typically higher than the steam required to complete the water-gas shift (WGS) reaction for the target CO / CO2 conversion. Thus, more steam is used than is required for WGS processes employing iron-based HTS catalysts. Using such steam in the process reduces the plant's thermal efficiency and reduces the amount of steam available for extraction, all of which harms the plant's overall economics. The limitations of iron-based catalysts are particularly evident in blue hydrogen plants, i.e., hydrogen plants with integrated carbon capture, which aim for maximum efficiency, maximum CO conversion, and the lowest possible net carbon intensity.

[0004] Furthermore, the economics of carbon capture processes drive plant scale to achieve associated economies of scale and further process intensification benefits. For example, blue H2 plants are often most economical at the largest possible scales for process intensification. These projects push the limits of historically largest plants and the range of process variables used. In particular, operating pressures are often higher than conventional H2 plants. Higher pressures allow for more gas to be produced within the same scale of equipment. Therefore, to improve the robustness of blue H2 plants and produce as much product as possible with maximum captured CO2, process pressures are often increased beyond levels previously considered typical for H2 plants. These process pressures have practical limits, with pressures above 65 bara and up to 100 bara being considered here. The lowest practical pressure for a POX reforming process is approximately 10 bara.

[0005] Catalyst manufacturers have recently addressed the issue of over-reduction of iron-based HTS catalysts by producing non-ferrous alternatives. These catalysts are less susceptible to over-reduction and can therefore be used at much lower S / DG ratios. Typical compositions of these non-ferrous catalysts include mixtures of zinc oxide, aluminum oxide, zinc-alumina spinel, and / or copper oxide with various promoters selected from Group 1A elements, Cu, Ti, Zr, or rare earth metals. However, problems remain, especially in reforming processes where syngas has a high CO concentration. The temperature generated by the released heat, especially in the first water-gas shift (i.e., HTS reactor), combined with CO remaining in the outlet stream, is the reason for metallurgical problems and metal dusting at and near the reactor outlet.

[0006] US 8,404,156 B2 teaches that the use of non-ferrous catalysts to carry out WGS reactions on synthesis gas streams is optimized by operating at an inlet temperature of 300-400°C and a pressure of 2.3-6.5 MPa (23-65 bara) with an oxygen-to-carbon (O / C) molar ratio in the range of 1.69-2.25. However, such prior art does not consider CO concentrations greater than 15% by volume on a dry basis, nor does it consider the effects of adiabatic temperature rise or pressures greater than 65 bara in the HTS reactor.

[0007] It is an object of the present invention to provide a process and system suitable for shift conversion of carbon monoxide rich synthesis gas to produce a shift product gas having an increased concentration of hydrogen.

[0008] It is desirable to increase the maintenance intervals for the high temperature water gas shift reactor and its downstream piping to reduce rework events. Summary of the Invention

[0009] The present invention relates to a process and system for shifting carbon monoxide and steam in a syngas to produce a shifted syngas with increased hydrogen and carbon dioxide concentrations. The process is carried out in a water-gas shift reactor using a non-iron-based high-temperature shift catalyst under conditions where conventional iron-based high-temperature shift catalysts tend to over-reduce and fail. The use of a suitable non-iron-based high-temperature shift catalyst essentially eliminates the minimum S / DG requirement to avoid over-reduction of the catalyst. The adiabatic temperature rise due to the thermal water-gas shift reaction is limited by adjusting the amount of steam introduced into the water-gas shift reactor in proportion to the syngas.

[0010] The basic subject matter is a process for concentrating hydrogen in synthesis gas, in which water, for example as quench water and / or scrubber water and / or injection water and / or in the form of steam, is added to synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C. This synthesis gas stream is introduced into a water-gas shift reactor, in which the synthesis gas stream is heated at an inlet temperature T in and reacting in a water gas shift reactor in the presence of a non-iron-based catalyst to produce a shifted synthesis gas having an increased hydrogen concentration, the shifted synthesis gas exiting the shift reactor at an outlet temperature T out The outlet temperature can be adjusted to a critical temperature T by adjusting the S / DG ratio through appropriate addition of water to maintain the O / C ratio above the upper O / C limit or below the lower O / C limit. crit stays below the critical temperature T crit The S / DG ratio is controlled to fall below the critical temperature. In other words, the S / DG ratio is adjusted to keep the O / C ratio outside the intermediate O / C range between the lower O / C limit and the upper O / C limit. The outlet temperature can be controlled to stay below the critical temperature by adding water appropriately.

[0011] The present invention takes into account practical limitations resulting from the temperature rise associated with exothermic WGS reactions. Such temperature rise is particularly high for reforming processes in which the syngas has a high CO concentration. Processes capable of producing syngas with high CO concentrations (>15% CO by volume on a dry basis) include partial oxidation (POX), autothermal reforming (ATR), dry reforming of methane (DRM), and steam methane reforming (SMR) at low S / C ratios. The exothermic heat released when reacting these high CO syngas streams in a WGS adiabatic reactor can generate high temperatures near the reactor outlet and in the gas exiting the reactor. These high temperatures, combined with the CO remaining in the shifted syngas stream, can cause metallurgical specified limits to be exceeded (e.g., metal dusting).

[0012] Examination of approaches taught in the prior art revealed that when the CO concentration exceeded 27% by volume, on a dry basis, the calculated outlet temperature from the HTS reactor exceeded the recommended temperature limit of 850°F (454°C) for the reactor components and downstream piping. Further investigation of possible S / DG ratios revealed the unexpected result that it was preferable to either significantly increase or decrease the S / DG ratio to manage the exothermic temperature rise. That is, as the CO concentration continued to increase beyond 27% by volume, the optimal S / DG bifurcated into two distinct desirable regions and an undesirable intermediate range. Therefore, the adiabatic temperature rise due to the heat release gas shift reaction was limited by adjusting the amount of steam introduced into each reactor with the syngas to either a sufficiently low O / C ratio or a sufficiently high O / C ratio, rather than the intermediate range.

[0013] Therefore, the critical temperature T crit may be selected to mitigate metal dusting corrosion. For example, for carbon steel piping and other components, the temperature of interest is typically about 850°F (450°C). Therefore, 850°F (450°C) is the T crit Temperatures above 1050°F (565°C) or above 950°F (510°C) are also important for metallurgical materials other than carbon steel. Therefore, 950°F (510°C) or even 1050°F (565°C) can be selected as T instead of 850°F (450°C). crit may be selected as.

[0014] The present invention takes into account the practical limitations of the metallurgy used in the WGS reactor and differs from the prior art in how increasing the carbon monoxide level in the feed to the WGS reactor results in higher temperatures, which in turn result in different ranges of desired S / DG and / or O / C ratios that are practically achievable.

[0015] The synthesis gas stream has an inlet temperature T in the range of about 200°C to about 400°C. in Alternatively, Tin The heating temperature may be in the range of about 200°C to about 400°C, about 210°C to about 390°C, about 220°C to about 380°C, about 230°C to about 370°C, about 240°C to about 360°C, or about 250°C to about 350°C.

[0016] The syngas may be cooled between the HTS reactor and the upstream syngas-forming reactor, for example, in a steam boiler. If cooled in a steam boiler, at least a portion of the steam generated in the steam boiler may be added to the syngas before it is fed to the HTS reactor. Alternatively, or in addition, steam may be added from one or more other steam sources.

[0017] The water gas shift reaction can be carried out on a desulfurized (sweet) syngas stream, i.e., a desulfurized (sweet) shift, thereby reducing catalyst poisoning and degradation. A sulfur-tolerant catalyst can be used. However, the process need not be carried out over a sulfur-tolerant catalyst, which broadens the range of suitable catalysts. The syngas stream can be low in sulfur, or preferably sulfur-free. The sulfur concentration in a low-sulfur syngas stream is less than 20 ppm, or less than 10 ppm, or less than 5 ppm, or less than 2 ppm. The sulfur concentration in a sulfur-free syngas stream is less than 1 ppm or less than 0.5 ppm.

[0018] When the process is carried out in a lower S / DG zone where O / C<lower O / C limit, the S / DG ratio may be adjusted to keep the O / C ratio of the syngas stream below 2.5. In this case, the lower O / C limit is 2.5. The lower O / C ratio allows for the conversion of syngas streams with higher CO concentrations at reactor outlet temperatures below the critical temperature. The higher the carbon monoxide concentration, the lower the lower O / C limit and the lower the S / DG and O / C ratios. The lower O / C limit may be reduced to 1.69, 1.6, or 1.5 or less.

[0019] The lower O / C ratio can be determined for a particular carbon monoxide concentration so that the reactor outlet temperature is equal to the critical temperature. The S / DG ratio can be adjusted to maintain the O / C ratio below or near the lower O / C limit to maximize the conversion rate under outlet temperature limit conditions. For example, the S / DG ratio can be adjusted to maintain the O / C ratio above 0.8 times the lower O / C limit, or above 0.9 times the lower O / C limit, or above 0.95 times the lower O / C limit.

[0020] When the process is carried out in an upper S / DG region where O / C>upper O / C limit, the S / DG ratio may be adjusted to keep the O / C ratio of the syngas stream above 3.0. In this case, the upper O / C limit is 3.0. A higher O / C ratio allows for the conversion of syngas streams with higher CO concentrations at reactor outlet temperatures below the critical temperature. The higher the carbon monoxide concentration, the higher the upper O / C limit and the higher the S / DG and O / C ratios. The upper O / C limit can be increased to 3.7, 4.25, or 5.0 or higher.

[0021] The upper O / C ratio can be determined for a particular carbon monoxide concentration so that the reactor outlet temperature is equal to the critical temperature. The S / DG ratio can be adjusted to maintain the O / C ratio above or near the upper O / C limit to minimize the amount of water added to the syngas under outlet temperature limit conditions. The S / DG ratio can be adjusted to maintain the O / C ratio below 1.3 times the upper O / C limit, or below 1.2 times the upper O / C limit, or below 1.1 times the upper O / C limit.

[0022] In the lower O / C zone, a syngas stream having a carbon monoxide concentration greater than 15 mol% and an S / DG ratio less than 0.5 may be introduced into the water-gas shift reactor. Thus, the reactor outlet temperature is kept below the critical temperature, effectively reducing or delaying metal dusting. Further reduction of the S / DG ratio allows for high-temperature shift conversion of syngas streams with higher carbon monoxide concentrations. Therefore, the S / DG ratio can be adjusted to remain below 0.34 or 0.27, or below 0.25, or even below 0.20. Adjusting the S / DG ratio to less than 0.25 allows for the conversion of syngas streams with carbon monoxide concentrations greater than 30 mol% while keeping the reactor outlet temperature below the critical temperature.

[0023] In the upper O / C zone, a synthesis gas stream having a carbon monoxide concentration greater than 15 mol% and an S / DG ratio greater than 0.67 may be introduced into the water-gas shift reactor. Thus, the reactor outlet temperature can be kept below the critical temperature, effectively reducing or delaying metal dusting. Further increasing the S / DG ratio allows for high-temperature shift conversion of synthesis gas streams with higher carbon monoxide concentrations. Therefore, the S / DG ratio can be adjusted to remain greater than 0.90, 1.0, or 1.1. Adjusting the S / DG ratio to greater than 1.2 allows for the conversion of synthesis gas streams with carbon monoxide concentrations greater than 30 mol% while keeping the reactor outlet temperature below the critical temperature.

[0024] For example, suppose the lower O / C limit is 1.69 and the upper O / C limit is 4.25. These limits are appropriate for carbon monoxide concentrations in the syngas stream of greater than 15 mol% up to 34 mol% on a dry basis. If the range to be avoided is broadened so that the lower O / C limit is 1.5 and the upper O / C limit is 5.0, the range of carbon monoxide concentrations in the syngas stream can also be broadened to greater than 15 mol% up to 40 mol% on a dry basis.

[0025] The subject process is suitable for shift conversion of synthesis gas streams having carbon monoxide concentrations greater than 15 mol% or greater than 20 mol%, on a dry basis. In particular, the carbon monoxide concentration may be 30 mol% or greater, on a dry basis. The carbon monoxide concentration of the synthesis gas stream may be greater than 50 mol% or even 60 mol%, on a dry basis. The present invention is particularly advantageous for synthesis gas streams having carbon monoxide concentrations between 30 mol% and 60 mol%, on a dry basis, inclusive.

[0026] The water gas shift reactor can be operated at pressures above 65 bara to achieve high conversion intensities and provide a system for carrying out the process in a compact design.

[0027] Each O / C limit is the carbon monoxide concentration in the syngas stream, X CO and / or inlet temperature T in Advantageously, the O / C limit to be applied, i.e., the upper O / C limit or the lower O / C limit, may be selected or calculated as a function of at least the carbon monoxide concentration, O / C(X CO ) or at least as a function of carbon monoxide concentration and inlet temperature O / C(T in ,X CO ) The respective O / C limits may be provided in the form of, and selected from, a predetermined table that assigns a lower O / C limit and / or an upper O / C limit, respectively, to different carbon monoxide concentrations in the syngas stream. Alternatively, the respective O / C limits may also be provided in the form of, and calculated based on, a formula.

[0028] The S / DG ratio, adjusted relative to the respective O / C limit, is the carbon monoxide concentration in the syngas stream, x CO and / or inlet temperature T in Advantageously, the applied S / DG ratio may be selected or calculated as a function of at least the carbon monoxide concentration, S / DG(X CO ) or at least as a function of carbon monoxide concentration and inlet temperature S / DG(T in ,X CO) The S / DG ratio may be provided as a predetermined table, which assigns different S / DG ratios to different carbon monoxide concentrations in the syngas stream, and may be selected from this table. Alternatively, it may also be provided in the form of a formula, and may be calculated based on this.

[0029] When a process is carried out in a lower O / C zone, if the carbon monoxide concentration of the syngas stream increases, the lower O / C limit may be lowered to a reduced lower O / C limit, and the S / DG ratio may be adjusted (in this case, reduced) to maintain the O / C ratio below the reduced lower O / C limit. If the carbon monoxide concentration of the syngas stream increases, the lower O / C limit may be lowered and the reduced O / C limit may be applied by correspondingly reducing the S / DG ratio in the ongoing process. However, this rule also applies to a process-by-process comparison of two processes for shift converting syngas streams with different carbon monoxide concentrations, i.e., without adjusting the S / DG ratio in each ongoing process.

[0030] When a process is carried out in an upper O / C zone, if the carbon monoxide concentration of the syngas stream increases, the upper O / C limit may be increased to the increased upper O / C limit, and the S / DG ratio may be adjusted (in this case, increased) to maintain the O / C ratio above the increased upper O / C limit. If the carbon monoxide concentration of the syngas stream increases, the upper O / C limit may be increased and the increased upper O / C limit may be applied by increasing the S / DG ratio in the ongoing process accordingly. However, this rule also applies to comparing two processes for shift conversion of syngas streams with different carbon monoxide concentrations, i.e., process-by-process, without adjusting the S / DG ratio in each ongoing process.

[0031] The subject process may include determining the carbon monoxide concentration of the syngas stream in mol%, volume%, or mass%, and varying the S / DG ratio as a function of the determined carbon monoxide concentration. When a syngas stream having an O / C ratio below a lower O / C limit is introduced into the syngas reactor, the S / DG ratio may be decreased in the event of a determined increase in the carbon monoxide concentration. When a syngas stream having an O / C ratio above an upper O / C limit is introduced into the syngas reactor, the S / DG ratio may be increased in the event of a determined increase in the carbon monoxide concentration. The carbon monoxide concentration may be determined based on a computer simulation of the upstream syngas formation process in which the syngas is formed and / or based on empirical values ​​of carbon monoxide concentration calculated from previous runs of the upstream syngas formation process. In a further development, the carbon monoxide concentration is determined by analyzing the feed syngas from the upstream syngas formation process, and / or the syngas stream entering the water-gas shift reactor, and / or the shifted syngas stream exiting the water-gas shift reactor, e.g., by gas chromatography. When analyzing the shifted syngas stream exiting the water gas shift reactor, the carbon monoxide concentration of the syngas stream entering the shift reactor can be determined by computer simulation of the water gas shift reaction occurring in the shift reactor.

[0032] Reactor outlet temperature T out The control of may consist of adjusting the S / DG ratio at the start of the process based on the carbon monoxide concentration of the synthesis gas stream, and optionally thereafter monitoring the carbon monoxide concentration while the process is running and readjusting the S / DG ratio based on this monitoring.

[0033] In an advantageous embodiment, controlling the reactor outlet temperature includes monitoring the outlet temperature during startup and / or during the run process via a temperature sensor. If the process is run in the lower O / C zone, an increase in the outlet temperature can be counteracted by decreasing the S / DG ratio. If the process is run in the upper O / C zone, an increase in the outlet temperature can be counteracted by increasing the S / DG ratio.

[0034] Reference temperature T refis T crit or a safety margin ΔT, i.e., T ref =T crit -ΔT only T crit may be provided at a value lower than T ref is the maximum temperature T that must not be exceeded or is only slightly exceeded. max As or S / DG ratio is T target The target temperature T target It can play a role as a target can be a reference variable for manual or automatic control. ref is T crit and T in as a function of the carbon monoxide concentration X CO and / or the S / DG ratio, may be predetermined and kept constant or may be varied during the start-up and / or run process. ref For example, T ref =T crit -A·(T crit -T in ) where A is a constant selected, for example, from the interval 0.1 to 0.2. crit To prevent this from happening, the S / DG ratio can be adjusted as soon as the monitored outlet temperature rises above the reference temperature.

[0035] The outlet temperature control may be performed manually by an operator, who monitors the reactor outlet temperature and adjusts the S / DG ratio by controlling one or more flow control devices, which may vary the flow rate of water added to the synthesis gas. Monitoring the reactor outlet temperature may also be performed manually by an operator, who monitors the reactor outlet temperature and adjusts the S / DG ratio by controlling one or more flow control devices, which may vary the flow rate of water added to the synthesis gas. out T ref This includes comparing with T ref As mentioned above, T max It can be used as:

[0036] In further developments, the control of the reactor outlet temperature is automated and implemented as feedforward control (open loop) or feedback control (closed loop). When implemented as forward control, changes in carbon monoxide concentration will either reduce or increase the S / DG ratio to bring the O / C ratio outside the critical mid-range and T out T crit In feedback control, the reference temperature is kept below the target temperature T target , i.e., may serve as a reference variable, and the reactor outlet temperature may be monitored, T target The S / DG ratio can be decreased or increased as a function of this comparison to keep the O / C ratio outside the critical mid-range.

[0037] Each comparison under automatic or manual control is ref and T out The goal is to calculate the deviation between the difference T ref -T out Or T out -T ref or ratio T out / T ref Or T ref / T out as, or T out T ref How close has it come to T? ref Less than or already T ref Any other measure that provides information about the degree of sensitivity may be calculated.

[0038] The subject process operates at a water gas shift reactor outlet temperature T out The temperature representative of the outlet temperature is measured and the temperature representative of the outlet temperature is measured and the maximum temperature T max or target temperature T target A reference temperature T may be provided as ref Advantageously, comparing T ref is at most T crit and preferably, T crit Less than 0.9 T crit Over 0.95 T critThe S / DG ratio may be selected to be greater than the target temperature. The process may further include modifying the S / DG ratio in response to the results of the comparison. In a process in which the synthesis gas stream is introduced into the water gas shift reactor at an O / C ratio below a lower O / C limit, the S / DG ratio may be decreased when the temperature representative of the reactor outlet temperature increases above the target temperature. In a process in which the synthesis gas stream is introduced into the water gas shift reactor at an O / C ratio above an upper O / C limit, the S / DG ratio may be increased when the temperature representative of the reactor outlet temperature increases above the target temperature. The comparison and / or subsequent S / DG adjustment may be performed by an operator, or automatically, if the process is performed under automatic control.

[0039] Metal dusting is not an instantaneous failure limit, but rather, operating above the critical temperature for metal dusting reduces the life of metallic materials in contact with hot synthesis gas, hence T crit The S / DG ratio is determined by the outlet temperature T out is above the critical temperature T for more than 80% or more than 90% of the operating time of the water gas shift reactor. crit It may be adjusted to stay below T crit by less than 10% or less than 5%, i.e., T crit <T out <1.1 T crit or T crit <T out <1.05 T crit An excess of only 10% or less than 20% of the water gas shift reactor operating time may be tolerated for short periods of time. The higher the temperature overshoot, the sooner an adjustment to the S / DG ratio is required.

[0040] The raw syngas may be formed in a syngas formation process upstream of the water-gas shift reactor, for example, by autothermal reforming (ATR), dry reforming of methane (DRM), or steam methane reforming (SMR) at a low S / C ratio. In particular, it may be formed by partial oxidation (POX) in a partial oxidation reactor. At least a portion of the water added to adjust the S / DG ratio may be added by injecting quench water into the raw syngas for partial oxidation.

[0041] The process may include removing soot and / or particles and / or sulfur and / or other contaminants from the syngas stream prior to reacting the syngas stream in the water-gas shift reactor. The removal may be carried out by wet scrubbing in a scrubber disposed to receive at least a portion of the syngas from an upstream syngas-forming reactor, such as a POX reactor, and the water-gas shift reactor may be disposed to receive at least a portion of the scrubbed syngas from the scrubber. At least a portion of the water added to adjust the S / DG ratio may be added in an optional intermediate removal step, for example, in the form of scrubber water.

[0042] The process may include, inter alia, an intermediate desulfurization step in which synthesis gas is formed by partial oxidation of a non-gaseous feedstock, such as coal, biomass, and / or hydrocarbon liquids. In embodiments in which the carbonaceous feedstock of the synthesis gas formation process is a gas, such as natural gas, refinery off-gas, other gaseous hydrocarbons, or a mixture thereof, desulfurization is preferably performed upstream of the synthesis gas formation process, the formation process using a desulfurized feed gas. However, even when the carbonaceous feedstock of the synthesis gas formation process is a gas, such as natural gas, refinery off-gas, other gaseous hydrocarbons, or a mixture thereof, desulfurization may be performed as an intermediate step between the initial formation process and the shift process, instead of or in addition to upstream desulfurization. At least a portion of the water added to adjust the S / DG ratio may be added in the optional intermediate desulfurization step, for example, in the form of scrubber water.

[0043] As the syngas flows through each scrubber, it can absorb or release water depending on its water-holding capacity. Therefore, the scrubber can function as a water saturator. The amount of water absorbed in each scrubber can be influenced by adjusting the temperature of the syngas at the inlet of the scrubber, which can be varied within the operating temperature limits of each scrubber. The hot syngas exiting the syngas formation reactor can be cooled in one or more coolers on its way to the scrubber to a temperature at which the syngas will absorb a certain amount of water as it flows through the scrubber, adjusting the water concentration of the syngas exiting the scrubber to be at or close to the S / DG ratio of the shift reactor. Therefore, adding water and adjusting the S / DG ratio can include, or even consist of, adjusting the temperature of the syngas on its way to the water-gas shift reactor.

[0044] At least a portion of the water added to adjust the S / DG ratio can be added directly to the syngas upstream of the water-gas-shift reactor while the syngas is being made up to the water-gas-shift reactor, for example, in the form of steam. Additionally, water can be sprayed into the static mixer through one or more spray nozzles to completely convert the directly added water into the steam phase and mix uniformly with the syngas before the mixture enters the water-gas-shift reactor.

[0045] Adjusting the S / DG ratio may involve or be achieved by only one or any two of the above three options. For example, a first portion of water may be added to the raw syngas as quench water and / or scrubber water, and a second or third portion may be added directly only to adjust the S / DG ratio. Adjusting the S / DG ratio may involve or be achieved by all three of the above options.

[0046] The non-ferrous catalyst may contain zinc, aluminum, and / or copper oxides along with one or more promoters. The catalyst may contain, in its active form, a mixture of zinc alumina spinel and zinc oxide. The promoter may be selected from Group 1A elements, Cu, Ti, Zr, and rare earth metals, and mixtures thereof, particularly Na, K, Rb, Cs, Cu, Ti, Zr, rare earth elements, and mixtures thereof. When the catalyst contains zinc and / or aluminum oxides, the Zn / Al molar ratio may be in the range of 0.5 to 1.0. In particular, the catalyst may contain, as a promoter, an alkali metal selected from the group consisting of Na, K, Rb, Cs, and mixtures thereof. The concentration of the one or more alkali metals may be 0.4 to 8.0 wt. % based on the weight of the oxidation catalyst.

[0047] A further subject of the invention is a system for enriching synthesis gas with hydrogen, the system comprising: a fluid transport means for replenishing and optionally processing the synthesis gas; a water source connected to the fluid transport means for adding water to the synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C; a water gas shift reactor operably arranged to receive a syngas stream from the fluid transport means, the water gas shift reactor comprising a reactor inlet and a reactor outlet for the shifted syngas; Water gas shift reactor outlet temperature T out a temperature sensor for sensing a temperature representative of the temperature of the heating element and generating a temperature signal based on the sensed temperature; one or more flow control devices capable of varying the total flow rate of water to the fluid transport means to adjust the S / DG ratio so that the O / C ratio is maintained above an upper O / C limit or below a lower O / C limit.

[0048] The fluid transport means may comprise piping for making up the syngas and may comprise a quench zone of the upstream syngas formation reactor, such as a quench zone of a gasifier, and / or a separate quench unit downstream of the syngas formation reactor, and / or a scrubber for removing soot and / or particles and / or sulfur and / or other contaminants, and / or one or more other syngas treatment devices. Desulfurization may be provided upstream of the syngas formation reactor instead of or in addition to optional desulfurization between the syngas formation reactor and the water-gas shift reactor. The feedwater source may comprise one or more water sources in liquid form and / or as steam. One or more flow control devices may be provided as control valves and / or pumps and / or compressors, including, for example, combinations of pumps or compressors with control valves.

[0049] The temperature sensor may sense the temperature of the shifted syngas by convective contact as it exits the water gas shift reactor or shortly thereafter, or at the downstream end of the reaction zone of the water gas shift reactor. Alternatively, the temperature sensor may measure the temperature of a component within the water gas shift reactor or the outlet pipe through which the shifted syngas exits the reactor outlet. Regardless of the type and location of the measurement, the sensed temperature should enable reliable conclusions to be drawn about the actual temperature of the syngas at the downstream end of the reaction zone and / or at the outlet of the reactor and / or in the pipe immediately following the reactor outlet. In this sense, the measured temperature is representative of the outlet temperature.

[0050] The system may include an output device disposed to receive the temperature signal from the temperature sensor and configured to output an output signal perceivable by a system operator, the output signal being representative of the reactor outlet temperature. The output device may be formed by or include a visual output device and / or an audible alarm. In response to the output signal, the system operator may then operate one or more of the one or more flow control devices to adjust the S / DG ratio to maintain the O / C ratio above the upper O / C limit or below the lower O / C limit. The output signal may indicate to the system operator that the reference temperature has been reached or just exceeded.

[0051] As an alternative to, or in addition to, manual control, the system may provide automatic control based on a comparison of the measured temperature with a reference temperature, such as the target temperature described above for the process. In such a further development, the system may comprise an electronic controller for controlling one or more flow control devices, the electronic controller being configured to calculate a temperature deviation between the sensed temperature and the reference temperature. The electronic controller may be further configured to command the one or more flow control devices to modify the total water flow rate in response to the calculated temperature deviation, and to adjust the S / DG ratio so that the O / C ratio is maintained above an upper O / C limit or below a lower O / C limit, thereby keeping the outlet temperature at or below the reference temperature.

[0052] The present invention is further directed to a system for concentrating hydrogen in a synthesis gas, the system comprising: a fluid transport means for replenishing and optionally processing the synthesis gas; a water source connected to the fluid transport means for adding water to the synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C; a water gas shift reactor operably arranged to receive a syngas stream from the fluid transport means, the water gas shift reactor comprising a reactor inlet and a reactor outlet for the shifted syngas; The carbon monoxide concentration X of the synthesis gas stream, either indirectly with the aid of computer simulation or directly CO a gas analyzer for determining the concentration of carbon monoxide in the exhaust gas and for generating a concentration signal representative of the determined concentration of carbon monoxide; one or more flow control devices capable of varying the total flow rate of water to the fluid transport means to adjust the S / DG ratio so that the O / C ratio is maintained above an upper O / C limit or below a lower O / C limit.

[0053] The fluid transport means may comprise piping for making up the syngas and may comprise a quench zone of the upstream syngas formation reactor, such as a quench zone of a gasifier, and / or a separate quench unit downstream of the syngas formation reactor, and / or a scrubber for removing soot and / or particles and / or sulfur and / or other contaminants, and / or one or more other syngas treatment devices. Desulfurization may be provided upstream of the syngas formation reactor instead of or in addition to optional desulfurization between the syngas formation reactor and the water-gas shift reactor. The feedwater source may comprise one or more water sources in liquid form and / or as steam. One or more flow control devices may be provided as control valves and / or pumps and / or compressors, including, for example, combinations of pumps or compressors with control valves.

[0054] A gas analyzer, such as a gas chromatograph, can be disposed between the upstream syngas formation reactor and the water gas shift reactor to analyze the composition of the syngas flowing from the syngas formation reactor to the water gas shift reactor. For example, a gas analyzer can be disposed near the inlet of the water gas shift reactor to analyze the composition of the syngas stream already conditioned for reaction in the water gas shift reactor. A preferred option is to position the gas analyzer downstream of the water gas shift reactor, conveniently near the reactor outlet, to analyze the composition of the shifted syngas. The carbon monoxide concentration of the syngas stream entering the water gas shift reactor can then be determined by a computerized process simulation of the reaction occurring in the water gas shift reactor. The reactor inlet temperature and / or outlet temperature can be used in conjunction with composition information calculated from the gas analyzer to determine the carbon monoxide concentration of the syngas stream.

[0055] The system may include an output device disposed to receive the concentration signal from the gas analyzer and configured to output an output signal perceivable by a system operator, the output signal being representative of the carbon monoxide concentration in the syngas stream entering the water-gas shift reactor. The output device may be formed by or may include a visual output device. In response to the output signal, the system operator may then operate one or more of the one or more flow control devices to thereby adjust the S / DG ratio such that the O / C ratio is maintained above an upper O / C limit or below a lower O / C limit.

[0056] The system may provide automatic control, as an alternative to or in addition to manual control, based on concentration signals from the gas analyzer. In such a further development, the system includes an electronic controller for controlling one or more flow control devices in response to concentration signals from the gas analyzer. The electronic controller may determine a lower O / C limit and / or an upper O / C limit based on a determined carbon monoxide concentration X in response to the concentration signals from the gas analyzer. COor select from a predetermined table that assigns respective lower and / or upper O / C limits to different values ​​of carbon monoxide concentration. Further, the electronic controller may be configured to determine the steam-to-dry gas molar ratio S / DG required to maintain the O / C ratio above the calculated or selected upper O / C limit or below the calculated or selected lower O / C limit. The electronic controller may be configured to command one or more flow control devices to modify the total water flow rate to match the required steam-to-dry gas molar ratio S / DG.

[0057] In embodiments in which a gas analyzer is located downstream of the water gas shift reactor, conveniently near the reactor outlet, to analyze the composition of the shifted syngas, the system may include a computing device configured to determine the carbon monoxide concentration of the syngas stream entering the water gas shift reactor from the composition of the shifted syngas by process simulation of the reactions occurring in the water gas shift reactor. The computing device may be configured to determine the carbon monoxide concentration of the syngas stream entering the water gas shift reactor using the reactor inlet temperature and / or the reactor outlet temperature in conjunction with composition information calculated from the gas analyzer. The computing device may be separate from and connected to the electronic controller unit for data transmission, or may be an integral part of the electronic controller. [Brief explanation of the drawings]

[0058] The invention will now be described, by way of example only, with reference to the drawings in which the features disclosed therein, each individually and in any combination of features, advantageously develop the subject matter of the claims and also the embodiments described above.

[0059] [Figure 1] 1 shows a system for concentrating hydrogen in synthesis gas by high temperature water-gas shift conversion and illustrates a process therefor, according to a first embodiment. [Figure 2]1 shows a system for concentrating hydrogen in syngas by high temperature water-gas shift conversion according to a second embodiment, illustrating a process therefor. [Figure 3] 1 shows a plot of reactor exit temperature versus steam to dry gas ratio for syngas streams having different carbon monoxide concentrations. [Figure 4] 1 shows a plot of reactor exit temperature versus oxygen to carbon ratio for the same synthesis gas stream. [Figure 5] 1 shows a plot of reactor exit temperature versus oxygen to carbon ratio for syngas streams of the same composition at different make-up pressures. DETAILED DESCRIPTION OF THE INVENTION

[0060] The following detailed description provides preferred exemplary embodiments only and is not intended to limit the scope, applicability, or configuration of the present invention. Rather, the following detailed description of preferred exemplary embodiments will provide those skilled in the art with an effective description for implementing preferred exemplary embodiments of the present invention, but it should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the present invention as defined by the claims.

[0061] As used herein, the articles "a" and "an" mean one or more when applied to any feature in embodiments of the invention described in the specification and claims. The use of "a" and "an" does not limit the meaning to a single feature unless such a limitation is specifically stated. The article "the" preceding a singular or plural noun or noun phrase refers to the particular named feature or features and may have singular or plural connotations depending on the context in which it is used.

[0062] The adjective "any" means one, some, or all of any amount indiscriminately.

[0063] The term "and / or" placed between a first entity and a second entity means one of: (1) the first entity, (2) the second entity, and (3) the first entity and the second entity. The term "and / or" placed between the last two entities of a list of three or more entities means at least one of the entities in the list, including any specific combination of entities in the list.

[0064] In the claims, numbers may be used to identify claimed steps (e.g., 1.1, 1.2, and 1.3). These numbers are used to aid in referencing process steps and are not intended to dictate the order in which the claimed steps are performed unless such order is specifically recited in the claims.

[0065] FIG. 1 illustrates a first exemplary embodiment of a process and system according to the present invention. In this process, a carbonaceous feed stream 1 is desulfurized in a desulfurization unit 2 by hydrodesulfurization, for example, but not limited to, using a hydrodesulfurization catalyst and a sulfur-removing sorbent. Feed stream 1 may be a gaseous feed stream. It may contain or consist of natural gas as its primary component. The desulfurized feed stream 3 is fed to a syngas formation reactor 5 to produce a raw syngas 6. The syngas formation reactor 5 is a partial oxidation (POX) reactor. An oxygen-containing fuel gas 4, e.g., pure oxygen, air, or oxygen-enriched air, is supplied in a substoichiometric amount to partially oxidize the carbonaceous components of feed stream 3 and form a raw syngas 6 containing hydrogen H, carbon monoxide CO, carbon dioxide CO, and possibly other components (e.g., nitrogen N, and methane CH).

[0066] The raw syngas 6 is fed to the high temperature water gas shift (HTS) reactor 12 via a fluid transport means for feeding, conditioning, and optionally treating the raw syngas 6 before undergoing the high temperature water gas shift reaction in the shift reactor 12. Conditioning may include cooling the syngas and / or adding water to the syngas to thereby adjust the steam to dry gas molar ratio S / G. The HTS reactor 12 is the first shift reactor downstream of the syngas formation reactor 5 and may be followed by one or more additional shift reactors, in particular medium and / or low temperature water gas shift reactors.

[0067] The fluid transport means may comprise a cooler 7 for cooling the hot syngas 6 from the reactor 5 by indirect heat exchange with water and / or direct cooling. The cooler 7 may be configured as a waste heat boiler (WHB) or a steam superheater or a quench unit. If the cooler 7 provides indirect heat exchange, preferably high pressure steam 27 may be generated for extraction and / or on-site power generation. The cooler 7 may provide hybrid cooling, as shown in the figure, where quench water 21 may be introduced into the syngas 6 for cooling and / or to adjust the S / DG ratio of the syngas stream.

[0068] At least a portion of the syngas 6, or the cooled syngas 8 if cooled in the optional cooler 7, may be processed. Such processing may include removal of soot and / or particles and / or sulfur and / or other contaminants. The fluid transport means may include a processing section 9 operably arranged to receive at least a portion of the syngas 6 or the cooled syngas 8 to form a purified syngas 10. The processing section 9 may include a wet scrubber 9a that scrubs at least a portion of the syngas 6 or 8 with the aid of scrubber water 22 in liquid or vapor form.

[0069] The desulfurized feed stream 3 typically enters the syngas formation reactor 5 at a temperature below 900°F (480°C). The raw syngas 6 exits the reactor 5 at a much higher temperature, typically in the range of 2200°F to 2500°F (1200°C to 1370°C), and can be advantageously cooled by indirect heat exchange and / or direct cooling in a cooler 7 immediately downstream of the reactor 5 to temperatures of concern for metal dusting, below 1050°F (565°C), or below 950°F (510°C), or below 850°F (450°C). If the processing section includes a wet scrubber, such as scrubber 9a, the syngas 6 can advantageously be cooled between the reactor 5 and the scrubber to a temperature high enough to absorb moisture (water) as the syngas flows through the scrubber. The treatment section 9 may include a dry filter 9b for removing soot and / or particles and / or sulfur and / or other pollutants. The dry filter 9b may replace the wet scrubber 9a or may be provided in addition. If the treatment section 9 includes a desulfurization unit, it may replace the upstream desulfurization unit 2 or may be provided in addition.

[0070] Water 23 in liquid form or in the form of steam or vapor can be added directly to the syngas, for example, by direct injection into a make-up line, spraying into an atomizing device, or introducing it via a mixing device as the syngas flows through a fluid transport means. Water 23 can be added directly to purified syngas 10, for example, to form syngas stream 11, which undergoes the water-gas shift reaction in HTS reactor 12. Water 23 can be sprayed into static mixer 23a via one or more atomizing nozzles, allowing the directly added water 23 to be completely in the steam phase and uniformly mixed with syngas 10 before syngas stream 11 enters HTS reactor 12.

[0071] The system may include a feedwater source 20 for adding quench water 21 and / or scrubber water 22 and / or direct water 23. The feedwater source 20 may include one or more water sources and / or connections for taking in water and / or one or more connections to one or more coolers of the system. If the system includes one or more coolers for cooling the syngas between the syngas formation reactor 5 and the HTS reactor 12 by indirect heat exchange, the feedwater source 20 may be operably arranged to receive at least a portion of the steam generated by at least one of the one or more coolers. For example, the feedwater source 20 may be operably arranged to receive at least a portion 28 of the steam 27 generated by the cooler 7 and configured to supply at least a portion of that steam to the syngas, e.g., as quench water 21 and / or scrubber water 22 and / or direct water 23.

[0072] The purified and conditioned syngas stream 11 is introduced into the HTS reactor 12 to form a shifted syngas 13 having an increased H concentration. The syngas stream 11 enters the reactor inlet of the reactor 12 and exits the reactor outlet. In the HTS reactor 12, carbon monoxide and steam are

number

[0073] The catalyst may contain oxides of zinc, aluminum, and / or copper together with one or more promoters. The catalyst may conveniently comprise, in its active form, a mixture of zinc alumina spinel and zinc oxide. The promoter may be selected from Group 1A elements, Cu, Ti, Zr, and rare earth metals, and mixtures thereof, particularly Na, K, Rb, Cs, Cu, Ti, Zr, rare earth elements, and mixtures thereof. When the catalyst contains oxides of zinc and / or aluminum, the Zn / Al molar ratio may be in the range of 0.5 to 1.0. In particular, the catalyst may contain, as a promoter, an alkali metal selected from the group consisting of Na, K, Rb, Cs, and mixtures thereof. The concentration of the one or more alkali metals may be 0.4 to 8.0 wt. % based on the weight of the oxidation catalyst.

[0074] In at least some embodiments, such as when a large amount of water vapor or steam must be added to the syngas 10, at least a portion of the syngas 10 may be bypassed through the static mixer 23a and the HTS reactor 12. The bypassed portion of the syngas 10 may be cooled and recombined with the shifted syngas 13. Bypassing at least a portion of the syngas 10 may reduce the total amount of steam required.

[0075] The system may include a CO2 removal unit 14 operably disposed to receive at least a portion of the shifted syngas 13 and configured to remove CO2 from the shifted syngas 13 to form a CO2-depleted syngas 15. The CO2 removal unit 14 may be configured as an adsorption unit containing an adsorbent for selectively adsorbing CO2. The CO2 removed from the shifted syngas 13 may be released or transported to a CO2 capture site or may be captured in situ. The system may further include a purification unit 16 operably disposed to receive at least a portion of the CO2-depleted syngas 15 and configured to form an H2-enriched product 17 and an H2-depleted tail gas 40.

[0076] Tail gas 40, which contains residual carbon monoxide and may contain CH and / or residual CO, or a first portion 42 of tail gas 40, may be fed to syngas formation reactor 5 via compressor 41. Tail gas 40 or tail gas portion 42 may be added to feed stream 1 or desulfurized feed stream 3 if upstream desulfurization is provided.

[0077] The tail gas 40 or a second portion 43 of the tail gas 40 may be supplied via a compressor 41 to a fired heater 45 for combustion with oxygen to generate thermal energy and produce steam 29. The oxygen may be supplied in the form of compressed air 44. Natural gas may also be supplied to the heater 45 and combusted with the tail gas 40 or the tail gas portion 43. Hot flue gas 47 from the heater 45 may be cooled by indirect heat exchange with water in a heat exchanger 46 to form steam 29. The steam 29 may be extracted on-site or expanded to generate power. Alternatively, a feedwater source 20 may be operably arranged to receive at least a portion of the steam 29 in addition to, or instead of, the steam 28.

[0078] FIG. 2 illustrates a second exemplary embodiment of a process and system according to the present invention. In this process, carbonaceous feed stream 1 can be desulfurized in desulfurization unit 2 by hydrodesulfurization, for example, but not limited to, using a hydrodesulfurization catalyst and a sulfur-removing sorbent. Feed stream 1, or desulfurized feed stream 3, if desulfurization unit 2 is present, is fed to syngas formation reactor 5 to produce raw syngas 6. Feed stream 1 can include coal, coke, heavy oil, tar sands, biomass, natural gas, or a mixture thereof. In principle, feed stream 1 can consist of any hydrocarbon or mixture of hydrocarbons. Syngas formation reactor 5 can be a partial oxidation (POX) reactor, in which oxygen-containing fuel gas 4, e.g., air, can be fed to partially oxidize the carbonaceous components of feed stream 3 to form raw syngas 6 containing hydrogen H, carbon monoxide CO, carbon dioxide CO, and possibly other components (e.g., nitrogen N, and methane CH).

[0079] The raw syngas 6 is fed to the high temperature water gas shift (HTS) reactor 12 via a fluid transport means for feeding, conditioning, and optionally treating the raw syngas 6 before undergoing the high temperature water gas shift reaction in the shift reactor 12. Conditioning includes adding water to the syngas, thereby adjusting the steam to dry gas molar ratio S / G.

[0080] Quench water 21 may be injected into at least a portion of the raw syngas 6 from the syngas formation reactor 5 in a quench zone 18 of the fluid transport means. The quench zone 18 may be disposed downstream of the reactor 5 or may be integrated into the reactor 5. Quenching may be performed particularly when the feed stream 1 consists of coal and / or biomass. When the feed stream 1 is a gas, such as natural gas, the raw syngas 6 may be, but typically is not, quenched.

[0081] At least a portion of the syngas 6, or, if quenched, the quenched syngas 8, may be processed. The processing may include removal of soot, particles, sulfur, and / or other contaminants from at least a portion of the syngas 6 or quenched syngas 8 in a fluid-borne scrubber 19 to form a purified syngas 10. The scrubber 19 may be a scrubber that scrubs at least a portion of the syngas 6 or 8, for example, with the aid of scrubber water 22 in liquid or vapor form. If the scrubber 19 is a desulfurization unit, it may replace the upstream desulfurization unit 2. The upstream desulfurization unit 2 may replace or be provided in addition to an intermediate desulfurization. A dry filter or syngas desulfurization reactor / adsorbent vessel may also replace or be provided in addition to the wet scrubber 19.

[0082] Water 23 in liquid or vapor form can be added directly to the syngas, for example, by direct injection into a make-up line, spraying into an atomizing device, or introducing it via a mixing device as it flows through a fluid transport means. Water 23 can be added directly to purified and optionally quenched syngas 10, for example, to form syngas stream 11, which undergoes the water-gas shift reaction in HTS reactor 12. Water 23 can be sprayed into static mixer 23a via one or more atomizing nozzles, allowing the directly added water 23 to be completely in the vapor phase and uniformly mixed with syngas 10 before syngas stream 11 enters HTS reactor 12.

[0083] The system may include a water source 20 for adding quench water 21 and / or scrubber water 22 and / or direct water 23 as described with respect to the first exemplary embodiment.

[0084] The purified and conditioned syngas stream 11 is introduced into the HTS reactor 12 to form a shifted syngas 13 with an increased H concentration. The syngas stream 11 enters the reactor inlet and exits the reactor outlet of the reactor 12. In the HTS reactor 12, carbon monoxide and steam react in a water gas shift reaction under adiabatic conditions over a non-ferrous catalyst, as also described above with respect to the first exemplary embodiment.

[0085] The system may further comprise a CO2 removal unit, a purification unit, and a fired heater, each operatively disposed and configured as described with respect to the first exemplary embodiment.

[0086] In any embodiment of the present invention, the shift reaction may be carried out at a pressure of 10 bara or greater, preferably 65 bara or greater, and may be carried out at pressures up to 100 bara or greater.

[0087] Due to the exothermic nature of the water gas shift reaction, the temperatures of the reactants and products vary along the length of the HTS reactor 10, with the inlet temperature T at the reactor inlet. in From the outlet temperature T at the reactor outlet out In many applications, Tin is above 270°C and can be as high as 400°C, with inlet temperatures below 370°C or below 360°C being preferred. Without proper control, outlet temperatures can reach 900°F (480°C) or 950°F (510°C) or 1050°F (565°C) or higher.

[0088] In particular, for the first water gas shift, i.e., HTS, reactor, these high temperatures combined with the remaining CO in the outlet stream may exceed the recommended limits of the reactor components and / or piping near or after the reactor outlet. Such limits may arise from metallurgical and / or catalyst degradation considerations. The reactor components and / or downstream piping may be heated to temperatures above a critical temperature T crit , i.e., it is desirable to maintain the temperature at a safety margin below the temperature of interest. In terms of metallurgical considerations such as metal dusting corrosion, 1050°F (565°C) is considered to be the critical temperature T crit To reduce the risk of metal dusting, 950°F (510°C) may be chosen instead. More conservatively, 850°F (450°C) is the critical temperature T crit can be selected as

[0089] The synthesis gas stream 11 entering the HTS reactor 12 has a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C. out Examining how T depends on the carbon monoxide and water concentrations in the synthesis gas stream 11 reveals that for a given S / DG ratio, an increase in carbon monoxide concentration increases T out It can be seen that for a given carbon monoxide concentration, the outlet temperature initially increases with increasing water concentration and, after exceeding a maximum temperature, decreases again with further increases in water concentration.

[0090] FIG. 3 shows the reactor outlet temperature T for synthesis gas stream 11 with different carbon monoxide concentrations. out 4 shows a plot of T vs. S / DG ratio for the same syngas flow. outFigure 1 shows a plot of the O / C ratio. The effect of increased carbon monoxide concentration was investigated by computational process simulation. Seven example temperature curves are shown for synthesis gas streams containing 15 mol%, 27 mol%, 29 mol%, 31 mol%, 33.5 mol%, 42 mol%, and 51 mol% carbon monoxide, respectively, based on dry gas. Carbon monoxide concentration is the main parameter being modified. The critical temperature T crit is plotted as a horizontal dashed line. In this example, the critical temperature Tcrit is conservatively chosen to be 850°F (450°C).

[0091] FIG. 5 shows the T for three examples of the same composition at make-up pressures of 10, 67, and 100 bar. out The plot of the make-up pressure vs. O / C ratio is shown. out It can be seen that the ion concentration has a very weak effect on the

[0092] The dry gas compositions (mol %) of three of the examples are shown in the table below. [Table 1]

[0093] The plot shows that as the carbon monoxide concentration increases, the outlet temperature T out However, as the carbon monoxide concentration continues to increase beyond 27 mol%, the optimum ranges for S / DG and O / C ratios diverge into two distinct regions and an intermediate range, which is undesirable due to increased metal dusting rates. The intermediate range is shown to be higher than the respective temperature curves T out (S / DG) or T out (O / C) is T crit 2. In the case of Example 2, a syngas stream with 31 mol % CO, the corresponding boundary lines are drawn from the preferred lower and upper regions at two points where they intersect with the horizontal dashed line.

[0094] For the synthesis gas stream of Example 2 with a CO concentration of 31 mol %, favorable conditions for the formation of metal dust are obtained if the following ratios are maintained: O / C<2.07 or O / C>3.7 S / DG<0.34 or S / DG>0.91

[0095] For the synthesis gas stream of Example 3 with a CO concentration of 33.5 mol %, favorable conditions for the formation of metal dust are obtained if the following ratios are maintained: O / C<1.69 or O / C>4.25 S / DG<0.25 or S / DG>1.19

[0096] Process simulations, of which the examples are merely representative, show that metal dusting of metal piping and other metal components can be prevented or at least delayed for syngas streams containing up to 29 mol% carbon dioxide on a dry basis when the shift reaction is carried out in the lower S / DG region, i.e., when the S / DG ratio is kept below 0.50. This keeps the O / C ratio below 2.5, which represents the lower end of the intermediate range of 29 mol% CO. Adjusting the S / DG ratio to even lower values ​​allows for further increases in carbon monoxide concentration. For example, keeping the S / DG ratio below 0.34 allows for an increase in carbon monoxide concentration up to 31 mol% on a dry basis. For example, keeping the S / DG ratio below 0.25 allows for an increase in carbon monoxide concentration up to 33.5 mol% on a dry basis. In the lower O / C and S / DG regions, the relationship between the decrease in S / DG and O / C ratios and the respective increase in the allowable carbon dioxide concentration is not linear: a further increase in carbon monoxide concentration can be compensated for by an ever smaller decrease in S / DG and O / C ratios.

[0097] Instead, the shift reaction can be carried out in the upper zone. For carbon monoxide concentrations up to 29 mol% on a dry basis, metal dusting of metal piping and other metal components can be prevented or at least delayed if the S / DG ratio is kept above 0.67. This keeps the O / C ratio above 3.0, which represents the upper end of the intermediate range for 29 mol% CO. Adjusting the S / DG ratio to higher values ​​allows for increased carbon monoxide concentrations. For example, keeping the S / DG ratio above 0.91 allows for increased carbon monoxide concentrations up to 31 mol% on a dry basis. For example, keeping the S / DG ratio above 1.19 allows for increased carbon monoxide concentrations up to 33.5 mol% on a dry basis.

[0098] To prevent or at least slow down metal dusting, a properly adjusted amount of water is added to the synthesis gas as it flows through the fluid transport means to the shift reactor 10. out T crit The O / C ratio can be controlled to remain below a predetermined lower O / C limit. Water can be added in a measured amount, i.e., at a measured total feed rate, to adjust the S / DG ratio so that the O / C ratio remains below a predetermined lower O / C limit or above a predetermined upper O / C limit. For syngas streams 11 with carbon monoxide concentrations greater than 15 mol% or greater than 20 mol%, a value of 2.5 can be selected as the lower O / C limit, and a value of 3.0 can be selected as the upper O / C limit. Syngas streams with carbon monoxide concentrations greater than 30 mol% can react under leaner steam conditions in the lower O / C region or richer steam conditions in the upper region because the undesirable O / C mid-range widens with increasing carbon monoxide concentration. Lowering the lower O / C limit to 2.07, 2.0, 1.69, or 1.6 or less allows the syngas stream to react with carbon monoxide concentrations greater than 30 mol%. Also, increasing the upper O / C limit to 3.7 or 4.25 or 5.0 or greater allows the synthesis gas stream to be reacted with carbon monoxide concentrations greater than 30 mol%.

[0099] Therefore, any of the system embodiments may include one or more flow control devices capable of changing the total flow rate of water to the fluid transport means to adjust the S / DG ratio so that the O / C ratio is maintained above the upper O / C limit or below the lower O / C limit. Each flow control device may be provided as a flow control valve. For example, flow control device 24 may be disposed in the supply of quench water 21 to quench zone 5 to increase or decrease the flow rate of quench water 21 to adjust the S / DG ratio, if present. Alternatively or additionally, flow control device 25 may be disposed in the supply of wash water 22 to increase or decrease the flow rate of wash water 21 to adjust the S / DG ratio, if present. A supply for adding direct water is particularly suitable when adjusting the S / DG ratio, because changing the flow rate of direct water 23 does not affect any other sub-processes, such as scrubbing. Therefore, flow control device 26 may be disposed in the make-up for directly added water 23 to increase or decrease the flow rate of direct water 23 to adjust the S / DG ratio. Any of the above control devices may function as the sole control device for adjusting the S / DG ratio or in combination with one or more of the other respective control devices.

[0100] The total flow rate of water added to the syngas, and therefore the S / DG ratio, can be adjusted during the initial operating stages of the system so that the O / C ratio is either in the lower or upper range and can then remain constant. In a basic embodiment, this can be achieved by manually adjusting one or more of the one or more flow control devices. During this initial adjustment process, the reactor outlet temperature can be monitored and controlled to remain below the critical temperature by adjusting the S / DG ratio, as explained above. As the process continues, T in <T ref ≦T crit and the reactor outlet temperature T out is the predetermined reference temperature T refIf the O / C ratio rises to 0.5, adjustments can be made. When this occurs, the total water flow rate is reduced or increased by operating one or more flow control devices to maintain the O / C ratio within each O / C zone. The following relationships may be valid: T ref >T in +0.7·(T crit -T in ), or T ref >T in +0.8·(T crit -T in ). T ref is T crit or lower by a safety margin. T ref <T crit -0.05·(T crit -T in ) or T ref <T crit -0.1 (T crit -T in ) As a rule of thumb, a safety margin of 10°C or more and / or 30°C or less may be selected.

[0101] Alternatively, the reactor outlet temperature may be adjusted to reflect the carbon monoxide concentration X of the synthesis gas stream 11 entering the shift reactor 12. CO X CO can be determined chromatographically during the process, or data from a previous equivalent process can be used. Depending on the O / C region in which the process is performed, the respective O / C limits are CO or may be provided in the form of a table that assigns a lower O / C limit and / or an upper O / C limit to gradually increasing carbon monoxide concentrations. From the total carbon and oxygen concentrations of the dry gas fraction in syngas stream 11, the S / DG ratio required to maintain the O / C ratio either below or above the respective O / C limit can be calculated, and the total flow rate of added water can be adjusted accordingly. The total carbon and oxygen concentrations of the dry gas fraction can be determined chromatographically during the process, or data from a previous equivalent process can be used.

[0102] The two control methods can be combined. During the start-up phase of the process, the respective O / C limit is selected from a table or calculated as a function of the carbon monoxide concentration, and the S / D ratio is adjusted to maintain the O / C ratio outside the undesirable intermediate range, thereby controlling the reactor outlet temperature. Once the process reaches steady state, the reactor outlet temperature is monitored relative to the maximum temperature mentioned above, and the S / DG ratio is adjusted as necessary to maintain the O / C ratio below the lower O / C limit or above the upper O / C limit.

[0103] 2, one or more sensors may be provided, such as flow meter 32, for determining the flow rate Δm / Δt of the syngas being fed to shift reactor 12 and generating a flow rate signal based on the determination. Flow meter 31 may be disposed anywhere between syngas formation reactor 5 and HTS reactor 12. In an exemplary embodiment, flow meter 31 is positioned to measure the flow rate of the syngas before water is added.

[0104] The system operates by adjusting the inlet temperature T of the synthesis gas stream 11 entering the shift reactor 12. in A temperature sensor 32 may be provided for sensing a temperature representative of the syngas stream 11 and generating an inlet temperature signal based on the sensed temperature. The temperature sensor 32 may sense the inlet temperature directly in convective contact with the syngas stream 11 or indirectly by sensing the temperature of a make-up line or reactor wall or reactor component near the inlet of the shift reactor 12.

[0105] Specifically, to control the reactor outlet temperature, the system adjusts the outlet temperature T of the synthesis gas stream 13 exiting the shift reactor 12. outand generating an outlet temperature signal based on the sensed temperature. The temperature sensor 33 may sense the temperature directly, for example, in convective contact with the shifted syngas 13 while it is still within the reactor 12 or while it is exiting the reactor 12, near the reactor outlet, or a short distance downstream from the outlet of the reactor 12. Alternatively, the temperature sensor 33 may sense the temperature indirectly by sensing the temperature of a make-up line or reactor wall or reactor component near the outlet of the shift reactor 12.

[0106] The system may include a gas analyzer 34, such as a gas chromatograph, to determine the composition of the shifted syngas 13 exiting the shift reactor 12 or the syngas stream 11 entering the reactor 12. The gas analyzer 34 measures the carbon monoxide concentration X CO , carbon dioxide concentration X CO2 , hydrogen concentration X H2 , and water concentration X H2O The gas analyzer 34 may be configured to determine the concentration of the main components of the shifted syngas 13 or syngas stream 11, such as carbon monoxide concentration X CO 2, the carbon monoxide concentration in the syngas stream 11 entering the shift reactor 12 can be determined in a computer-aided simulation of the reactions occurring in the shift reactor 12 by back-calculating from the composition of the shift syngas 13. The gas analyzer 34 can be configured to generate concentration signals representative of each gas component, if present, and in particular, a concentration signal representative of the carbon monoxide concentration.

[0107] In a further development, automatic control may be provided, as shown in Figure 2. The system may comprise an electronic controller 30 for controlling one or more flow control devices 24-26 in response to a temperature signal from a temperature sensor 33 and / or a concentration signal from a gas analyzer 34. "Controlling one or more control devices 24-26" means controlling one or more flow control devices, inclusive, that are present to control the amount of water added to form the synthesis gas stream 11.

[0108] The electronic controller 30 compares the sensed temperature with a reference temperature T ref , which may be stored in a data memory of the controller 30 or may be provided by an external source. ref is T crit , and T in and / or X CO The flow rate may be held constant or adapted during the process as a function of one or more process variables, such as the temperature deviation and / or the S / DG. The electronic controller 30 may be configured to calculate the flow rate reduction or increase required to bring the outlet temperature closer to the target temperature, or to select such a flow rate reduction or increase from a predetermined table that assigns each flow rate reduction or increase to a different value of temperature deviation. The electronic controller 30 is configured to command one or more flow control devices 24-26 to modify the total flow rate of water, such as quench water 21 and / or wash water 22 and / or direct water 23, in response to the calculated temperature deviation, if present, and to adjust the S / DG ratio so that the O / C ratio is maintained below the lower O / C limit when the shift reaction is performed in the lower O / C zone, or above the upper O / C limit when the shift reaction is performed in the upper O / C zone.

[0109] Instead of, or in addition to, using the reactor outlet temperature as a control variable, the concentration signal from the gas analyzer 34 may be used to control the reactor outlet temperature. The electronic controller 30 may control one or more of the one or more flow control devices 24-26 in response to the concentration signal from the gas analyzer 34. The electronic controller 30 controls the determined carbon monoxide concentration X in response to the concentration signal from the gas analyzer 34 and depending on the O / C range in which the HTS reactor 12 is operated. CO or to select each upper O / C limit from a predetermined table that assigns each lower O / C limit and / or upper O / C limit to different values ​​of carbon monoxide concentration. Electronic controller 30 may be configured to select or calculate the S / DG ratio needed to maintain the O / C ratio above the upper O / C limit or below the lower O / C limit. Electronic controller 30 may further be configured to command one or more flow control devices 24-26 to modify the total water flow rate to match the required S / DG ratio.

[0110] The system of the first exemplary embodiment may include one or more of the sensors, including all of those shown and described in connection with the second exemplary embodiment, and may also include an electronic controller 30. The HTS reactor outlet temperature T out With respect to the control of , the process of the first exemplary embodiment may be implemented as described for the second exemplary embodiment.

[0111] In a basic embodiment where the S / DG ratio is manually adjusted, no electronic controller is required. The electronic controller 30 is an optional component of the present system and process. In a basic embodiment, the controller 30 controls the outlet temperature T out and / or inlet temperature T in and / or carbon monoxide concentration X CO The output may be replaced with an output device, such as an optical display, for monitoring process variables such as the reactor outlet temperature, T critcan be kept below

Claims

1. 1. A method for concentrating hydrogen in synthesis gas, comprising: H ２ adding O to the synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C; introducing the synthesis gas stream into a water gas shift reactor, wherein the synthesis gas stream has an inlet temperature T ｉｎ and introducing The synthesis gas stream is reacted in the water gas shift reactor in the presence of a non-iron based catalyst to produce an outlet temperature T ｏｕｔ producing a shifted syngas having The outlet temperature T is adjusted by adjusting the S / DG ratio to maintain the O / C ratio below a lower O / C limit or above an upper O / C limit. ｏｕｔ , the critical temperature T ｃｒｉｔ or remains below the critical temperature T ｃｒｉｔ and controlling the temperature to decrease to:

2. 10. The method of claim 1, wherein the synthesis gas stream comprises sulfur at a concentration of less than 10 ppm.

3. The critical temperature T ｃｒｉｔ 2. The method of claim 1, wherein the temperature is 1050°F (565°C).

4. Each of the O / C limits is determined by the carbon monoxide concentration of the synthesis gas stream and / or the inlet temperature T ｉｎ The method of claim 1 , wherein the Δt is selected or calculated as a function of

5. The method of claim 1 , wherein the lower O / C limit is 2.5 and / or the upper O / C limit is 3.

0.

6. 2. The method of claim 1, wherein the lower O / C limit is 1.69, the upper O / C limit is 4.25, and the carbon monoxide concentration of the syngas stream is in the range of 15 mol% to 34 mol% on a dry basis.

7. 10. The method of claim 1, wherein the lower O / C limit is 1.5, the upper O / C limit is 5.0, and the carbon monoxide concentration of the syngas stream is in the range of 15 mol% to 50 mol% on a dry basis.

8. 10. The method of claim 1, wherein the carbon monoxide concentration of the synthesis gas stream is greater than 15 mol% on a dry basis.

9. 10. The process of claim 1, wherein the synthesis gas stream having a carbon monoxide concentration greater than 15 mol% and an S / DG ratio less than 0.5 is introduced into the water gas shift reactor.

10. 10. The process of claim 1, wherein the synthesis gas stream having a carbon monoxide concentration greater than 15 mol% and an S / DG ratio greater than 0.67 is introduced into the reactor.

11. The outlet temperature T of the water gas shift reactor ｏｕｔ measuring a temperature representative of The critical temperature T ｃｒｉｔ A reference temperature T equal to or lower by a safety margin than ｒｅｆ and the outlet temperature T ｏｕｔ The temperature representative of the reference temperature T ｒｅｆ Compare with and modifying the S / DG ratio in response to the result of the comparison; The syngas stream is introduced into the syngas reactor at an O / C ratio less than the lower O / C limit, and the outlet temperature T ｏｕｔ The temperature representative of the reference temperature T ｒｅｆ When the S / DG ratio is increased to above 1000 kJ / s, the S / DG ratio is decreased, or The syngas stream is introduced into the syngas reactor at an O / C ratio above the upper O / C limit, and the outlet temperature T ｏｕｔ The temperature representative of the reference temperature T ｒｅｆ 2. The method of claim 1, wherein the S / DG ratio is increased when the temperature rises above 1000°C.

12. 2. The method of claim 1, wherein as the carbon monoxide concentration of the syngas stream increases, the lower O / C limit is lowered to a reduced lower O / C limit and / or the upper O / C limit is increased to an increased upper O / C limit, and the S / DG ratio is adjusted to maintain the O / C ratio below the reduced lower O / C limit or above the increased upper O / C limit.

13. determining a carbon monoxide concentration of the synthesis gas stream; and varying the S / DG ratio as a function of the determined carbon monoxide concentration; the syngas stream having an O / C ratio below the lower O / C limit is introduced into a syngas reactor to reduce the S / DG ratio to neutralize the determined increase in carbon monoxide concentration; or 2. The method of claim 1, wherein the syngas stream having an O / C ratio above the upper O / C limit is introduced into the syngas reactor and the determined increase in carbon monoxide concentration is counteracted by increasing the S / DG ratio.

14. 10. The method of claim 1, wherein at least a portion of the water is added directly to the syngas upstream of the water-gas-shift reactor while the syngas is being fed to the water-gas-shift reactor, and / or wherein at least a portion of the water is added by quenching and / or scrubbing with water.

15. 10. The method of claim 1, wherein the non-iron based catalyst, in its active form, comprises a mixture of alumina zinc spinel and zinc oxide in combination with a promoter selected from the group consisting of Na, K, Rb, Cs, Cu, Ti, Zr, and mixtures thereof.

16. 17. The method of claim 16, wherein the non-iron based catalyst has a Zn / Al molar ratio of 0.5 to 1.0 and a concentration of an alkali metal selected from the group consisting of Na, K, Rb, Cs, and mixtures thereof of 0.4 to 8.0 wt. %, based on the weight of the oxidation catalyst.

17. T ｉｎ 2. The method of claim 1, wherein the temperature is in the range of 270°C to 400°C.

18. 1. A method for concentrating hydrogen in synthesis gas, comprising: H ２ adding O to the synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C; introducing the synthesis gas stream into a water gas shift reactor, wherein the synthesis gas stream has an inlet temperature T ｉｎ and introducing The synthesis gas stream is reacted in the water gas shift reactor in the presence of a non-iron based catalyst to produce an outlet temperature T ｏｕｔ producing a shifted syngas having The outlet temperature T ｏｕｔ measuring a temperature representative of the carbon monoxide concentration X of the synthesis gas stream ＣＯ and determining The outlet temperature T is adjusted by adjusting the S / DG ratio to maintain the O / C ratio below a lower O / C limit or above an upper O / C limit. ｏｕｔ to remain below 1050°F (565°C); The lower O / C limit and the upper O / C limit are T ｉｎ and / or X ＣＯ The method is determined as a function of

19. 1. A system for concentrating hydrogen in a synthesis gas, the system comprising: a fluid transport means for replenishing and optionally processing said synthesis gas; a water source connected to the fluid transport means for adding water to the synthesis gas to form a synthesis gas stream comprising hydrogen, carbon monoxide, and steam, the synthesis gas stream having a steam to dry gas molar ratio S / DG and an oxygen to carbon molar ratio O / C; a water gas shift reactor operably disposed to receive the syngas stream from the fluid transport means, the water gas shift reactor comprising a reactor inlet and a reactor outlet for shifted syngas; The outlet temperature T of the water gas shift reactor ｏｕｔ a temperature sensor for sensing a temperature representative of the temperature of the heating element and generating a temperature signal based on the sensed temperature; one or more flow control devices capable of varying the total flow rate of water to the fluid transport means to adjust the S / DG ratio so that the O / C ratio is maintained above an upper O / C limit or below a lower O / C limit.

20. the carbon monoxide concentration X of the synthesis gas stream ＣＯ 20. The system of claim 19, further comprising a gas analyzer for determining a concentration of carbon monoxide in the exhaust gas and generating a concentration signal representative of the determined concentration of carbon monoxide.

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