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

Abstract

A process for enriching synthesis gas with hydrogen is presented. The method includes adding H2O to the syngas to form a syngas stream comprising hydrogen, carbon monoxide, and steam. The syngas stream has a molar ratio of steam to dry gas S / DG; and the molar ratio of oxygen to carbon O / C. The method includes introducing a syngas stream into a water-gas shift reactor and reacting the syngas stream in the water-gas shift reactor in the presence of a non-iron-based catalyst to produce a shifted syngas. The method further includes controlling the outlet temperature of the syngas stream to be maintained at or below the critical temperature or to or below the critical temperature by adjusting the S / DG ratio to maintain the O / C ratio below the O / C lower limit or above the O / C upper limit.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Application No. 17 / 960,854, filed on October 6, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention generally relates to converting carbon monoxide and steam in synthesis gas into a hydrogen-rich shifted synthesis gas, and more particularly to converting synthesis gas containing elevated levels of carbon monoxide in a high temperature water-gas shift reaction. The synthesis gas fed to the water-gas shift reaction may contain more than 15% carbon monoxide by volume on a dry basis. Background Art

[0004] Historically, high temperature shift (HTS) reactors have used catalysts made of iron and chromium oxides. 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 reduction potential of the syngas, 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 to achieve the targeted CO to CO2 conversion. Therefore, for WGS processes employing iron-based HTS catalysts, more steam is used than required. The use of this steam in the process reduces the thermal efficiency of the plant and reduces the amount of steam available for output, all of which is detrimental to the overall plant economics. The limitations of iron-based catalysts are particularly prominent in blue hydrogen plants, which are hydrogen plants with integrated carbon capture, where the goals are maximum efficiency, maximum CO conversion, and the lowest possible net carbon intensity.

[0005] In addition, the economics of the carbon capture process drive the scale-up of the equipment to achieve the benefits of the associated economies of scale and increased process intensification. For example, blue H2 equipment is generally most economical at the largest scale possible with the greatest process intensification. These projects are pushing the boundaries of the largest scale equipment ever built and the range of process variables used. In particular, the operating pressure is generally higher than conventional H2 equipment. Higher pressures allow more gas to be produced within the same size equipment. In order to increase the strength of the blue H2 equipment and to produce as much product as possible while capturing the maximum degree of CO2, the process pressure is therefore generally increased to levels that exceed those previously considered typical for H2 equipment. These process pressures have practical limits, but pressures greater than 65 bara and up to 100 bara are now being considered. The lowest practical pressure for the POX reforming process is about 10 bara.

[0006] In recent years, catalyst manufacturers have solved the over-reduction problem of iron-based HTS catalysts by producing non-iron-based alternative catalysts. These catalysts are not susceptible to over-reduction at all and can therefore be used at much lower S / DG ratios. Typical compositions of these non-iron-based 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 still exist, especially in reforming processes where the synthesis gas has a high CO concentration. The temperatures generated by the released exothermic heat, especially in the first water-gas shift, i.e. in the HTS reactor, combined with the remaining CO in the outlet stream, are the cause of metallurgical problems and metal dusting at and near the reactor outlet.

[0007] US 8,404,156 B2 teaches optimizing the WGS reaction of a synthesis gas stream using a non-iron based catalyst by operating at an oxygen to carbon (O / C) molar ratio in the range of 1.69 to 2.25 at an inlet temperature of 300°C-400°C and a pressure of 2.3-6.5 MPa (23-65 bara). However, this 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 increases or pressures above 65 bara in the HTS reactor.

[0008] It is an object of the present invention to provide a process and a system suitable for shift conversion of a carbon monoxide rich synthesis gas to produce a shifted product gas having an increased hydrogen concentration.

[0009] It is desirable to extend maintenance intervals and reduce refurbishment events for a high temperature water-gas shift reactor and its downstream piping. Summary of the invention

[0010] The present invention relates to a process and system for shift conversion of carbon monoxide and steam in synthesis gas to produce a shifted synthesis gas with increased hydrogen concentration and carbon dioxide. The process is carried out in a water-gas shift reactor using a non-iron-based high temperature shift catalyst under conditions where a conventional iron-based high temperature shift catalyst is susceptible to over-reduction and may fail. The use of a suitable non-iron-based high temperature shift catalyst substantially eliminates the requirement for a minimum S / DG to avoid over-reduction of the catalyst. The adiabatic temperature rise caused by the exothermic water-gas shift reaction is limited by regulating the amount of steam introduced into the water-gas shift reactor with the synthesis gas.

[0011] The basic subject matter is a process for enriching synthesis gas with hydrogen. In the process, water is added to the synthesis gas, for example as quench water and / or scrubber water and / or injection water, and / or in the form of steam, 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. The synthesis gas stream is introduced into a water-gas shift reactor, the synthesis gas stream having an inlet temperature T at the reactor inlet. 入口 , 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 leaving the shift reactor having an outlet temperature T higher than the inlet temperature 出口 By adjusting the S / DG ratio to maintain or bring the O / C ratio above the upper O / C limit or below the lower O / C limit by appropriate addition of water, the outlet temperature is controlled to be maintained at the critical temperature T 临界 or below the critical temperature T 临界 , or drops to the critical temperature T 临界 or below the critical temperature T 临界 In other words, the S / DG ratio is adjusted so that the O / C ratio is outside the intermediate O / C range extending from the lower O / C limit to the upper O / C limit. The outlet temperature can be controlled by appropriate addition of water to maintain it below the critical temperature.

[0012] The present invention takes into account practical limitations imposed by the temperature rise associated with the exothermic WGS reaction. This temperature rise is particularly high for reforming processes in which the syngas has a high CO concentration. Processes that can produce syngas with high CO concentrations (CO>15 vol%, 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 these high CO syngas streams react in a WGS adiabatic reactor can produce high temperatures near the outlet of the reactor and in the gas leaving the reactor. These high temperatures, together with the remaining CO in the shifted syngas stream, can result in exceeding metallurgical limits, for example leading to metal dusting.

[0013] When the methods taught in the prior art were examined, it was found that when the CO concentration exceeded 27 volume % on a dry basis, the calculated outlet temperature from the HTS reactor exceeded the recommended temperature limit of 850°F (454°C) for reactor components and downstream piping. Upon further investigation of possible S / DG ratios, an unexpected result was found that significantly increasing or decreasing the S / DG ratio was preferred for controlling the exothermic temperature rise. That is, as the CO concentration continued to increase above 27 volume %, the optimal S / DG bifurcated into two separate desired domains and an undesirable intermediate range. Therefore, the adiabatic temperature rise caused by the exothermic water-gas shift reaction is limited by adjusting the amount of steam introduced into the corresponding reactor along with the syngas to a sufficiently low O / C ratio or a sufficiently high O / C ratio, rather than to an intermediate range.

[0014] The critical temperature T can be selected accordingly 临界 , to reduce metal dusting corrosion. For example, for carbon steel pipes and other components, the temperature of concern is usually around 850℉ (450℃). Therefore, 850℉ (450℃) can be selected as T 临界 Temperatures above 1050°F (565°C) or above 950°F (510°C) are also critical for metallurgies other than carbon steel. Therefore, 950°F (510°C) or even 1050°F (565°C) may be selected as T 临界 , instead of 850℉(450℃).

[0015] The present invention differs from the prior art in that it takes into account the practical limitations of the metallurgy for a WGS reactor and how increasing the carbon monoxide level in the feed to the WGS reactor produces higher temperatures, which in turn leads to different desired ranges of S / DG ratios and / or O / C ratios that are practically feasible.

[0016] The synthesis gas stream may be supplied at an inlet temperature T in the range of about 200°C to about 400°C. 入口 Entering the water-gas shift reactor. Alternatively, T 入口 It 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.

[0017] 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 being fed to the HTS reactor. Steam may alternatively or additionally be added from one or more other steam sources.

[0018] The water-gas shift reaction can be carried out on the desulfurized synthesis gas stream, i.e., as a desulfurization shift. Thus, catalyst poisoning and deterioration are reduced. Sulfur-tolerant catalysts can be used. However, the process does not have to be carried out on sulfur-tolerant catalysts, which expands the range of suitable catalysts. The synthesis gas stream can be low-sulfur or preferably sulfur-free. The sulfur concentration in the low-sulfur synthesis gas 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 the sulfur-free synthesis gas stream is less than 1 ppm or less than 0.5 ppm.

[0019] When the process is carried out in the lower limit of the S / DG domain (where O / C < O / C lower limit), the S / DG ratio can be adjusted to keep the O / C ratio of the synthesis gas stream below 2.5. In this case, the O / C lower limit is 2.5. The O / C ratio lower limit allows the conversion of synthesis gas streams with higher CO concentrations at reactor outlet temperatures below the critical temperature. The higher the carbon monoxide concentration, the lower the O / C lower limit, as well as the S / DG ratio and the O / C ratio. The O / C lower limit can be reduced to 1.69 or 1.6 or 1.5 or lower.

[0020] For a specific carbon monoxide concentration, the O / C ratio lower limit can be determined such that the reactor outlet temperature equals the critical temperature. The S / DG ratio can be adjusted to keep the O / C ratio below but close to the O / C lower limit, so as to maximize the conversion rate under the outlet temperature limit conditions. For example, the S / DG ratio can be adjusted to keep the O / C ratio higher than 0.8 times the O / C lower limit or higher than 0.9 times the O / C lower limit or higher than 0.95 times the O / C lower limit.

[0021] When the process is carried out in the upper limit of the S / DG domain (where O / C > O / C upper limit), the S / DG ratio can be adjusted to keep the O / C ratio of the synthesis gas stream above 3.0. In this case, the O / C upper limit is 3.0. The O / C ratio upper limit allows the conversion of synthesis gas streams with higher CO concentrations at reactor outlet temperatures below the critical temperature. The higher the carbon monoxide concentration, the higher the O / C upper limit, as well as the S / DG ratio and the O / C ratio. The O / C upper limit can be increased to 3.7 or 4.25 or 5.0 or higher.

[0022] For a specific carbon monoxide concentration, the O / C ratio upper limit can be determined such that the reactor outlet temperature equals the critical temperature. The S / DG ratio can be adjusted to keep the O / C ratio above but close to the O / C upper limit, so as to minimize the amount of water added to the syngas under the outlet temperature limit conditions. The S / DG ratio can be adjusted to keep the O / C ratio below 1.3 times the O / C upper limit or below 1.2 times the O / C upper limit or below 1.1 times the O / C upper limit.

[0023] In the lower limit of the O / C domain, the synthesis gas stream can be introduced into the water-gas shift reactor with a carbon monoxide concentration greater than 15 mol % and an S / DG ratio less than 0.5. Therefore, the reactor outlet temperature is kept below the critical temperature, and metal dusting is effectively reduced or delayed. Further reduction of the S / DG ratio allows high temperature shift conversion of synthesis gas 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 conversion of synthesis gas streams with a carbon monoxide concentration greater than 30 mol % while keeping the reactor outlet temperature below the critical temperature.

[0024] In the upper limit of the O / C domain, the synthesis gas stream can be introduced into the water-gas shift reactor with a carbon monoxide concentration greater than 15 mol % and an S / DG ratio greater than 0.67. Therefore, the reactor outlet temperature can be kept below the critical temperature, and metal dusting can be effectively reduced or delayed. A further increase in the S / DG ratio enables high temperature shift conversion of a synthesis gas stream with a higher carbon monoxide concentration. Therefore, the S / DG ratio can be adjusted to remain above 0.90 or 1.0 or 1.1. Adjusting the S / DG ratio to above 1.2 allows conversion of a synthesis gas stream with a carbon monoxide concentration greater than 30 mol % while keeping the reactor outlet temperature below the critical temperature.

[0025] For example, the O / C lower limit is set to 1.69 and the O / C upper limit is set to 4.25. These limits are suitable for carbon monoxide concentrations greater than 15 mol% and up to 34 mol% on a dry basis in the synthesis gas stream. If the range to be avoided is widened so that the O / C lower limit is 1.5 and the O / C upper limit is 5.0, the range of carbon monoxide concentrations in the synthesis gas stream can also be widened from greater than 15 mol% on a dry basis to up to 40 mol%.

[0026] The subject process is suitable for the shift conversion of the synthesis gas stream with a carbon monoxide concentration greater than 15 mol % or greater than 20 mol % on a dry basis. In particular, the carbon monoxide concentration can be 30 mol % or higher on a dry basis. The carbon monoxide concentration of the synthesis gas stream can be greater than 50 mol % or even 60 mol % on a dry basis. The present invention is particularly conducive to converting the synthesis gas stream with a carbon monoxide concentration between 30 mol % and 60 mol % and including range limits on a dry basis.

[0027] The water-gas shift reactor can be operated at pressures above 65 bara to achieve high conversion severity and to realize a system for carrying out the process in a compact design.

[0028] The corresponding O / C limit can be taken as the carbon monoxide concentration X of the synthesis gas stream. CO and / or inlet temperature T入口 Advantageously, the O / C limit to be applied, ie the upper O / C limit or the lower O / C limit, is selected or calculated as a function of the carbon monoxide concentration O / C (X CO ), or at least as a function of the carbon monoxide concentration and the inlet temperature O / C (T 入口 , X CO ) is selected or calculated as a function of ). The corresponding O / C limit value may be provided in the form of a predetermined table, which assigns the O / C lower limit and / or the O / C upper limit to different carbon monoxide concentrations of the synthesis gas stream, respectively; and is selected from the table. The corresponding O / C limit value may alternatively be provided in the form of a calculation formula and calculated on the basis of this.

[0029] The S / DG ratio to be adjusted relative to the corresponding O / C limit can be used as the carbon monoxide concentration X of the synthesis gas stream. CO and / or inlet temperature T 入口 Advantageously, the S / DG ratio to be applied is at least as a function of the carbon monoxide concentration S / DG(X CO ), or at least as a function of CO concentration and inlet temperature S / DG(T 入口 , X CO ) to be selected or calculated. The S / DG ratio may be provided as a predetermined table which assigns the S / DG ratios to different carbon monoxide concentrations of the synthesis gas stream respectively; and selected from the table. It may alternatively be provided in the form of a calculation formula and calculated on the basis of this.

[0030] When the process is carried out within the lower limit of the O / C domain, the O / C lower limit can be reduced to the reduced O / C lower limit and the S / DG ratio can be adjusted, in this case reducing the S / DG ratio, to keep the O / C ratio below the reduced O / C lower limit when the carbon monoxide concentration of the synthesis gas stream increases. If the carbon monoxide concentration of the synthesis gas stream increases, the O / C lower limit can be reduced and the reduced O / C limit applied by a corresponding reduction in the S / DG ratio in the ongoing process. However, this rule also applies to the comparison of two processes for shift conversion of synthesis gas streams that differ in carbon monoxide concentration, i.e. the comparison of processes with each other without adjusting the S / DG ratio during the corresponding operation.

[0031] When the process is carried out in the upper O / C range, as 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 increasing the S / DG ratio, 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 applied by a corresponding increase in the S / DG ratio in the ongoing process. However, this rule also applies to a comparison of two processes for shift conversion of a syngas stream that differ in carbon monoxide concentration, i.e. a comparison of processes without adjusting the S / DG ratio during the respective operations.

[0032] The subject process can include determining the carbon monoxide concentration of the synthesis gas stream in mol%, volume % or mass %, and changing the S / DG ratio according to the determined carbon monoxide concentration. If the synthesis gas stream is introduced into the synthesis gas reactor with an O / C ratio lower than the O / C lower limit, the S / DG ratio can be reduced in the case of a determined increase in the carbon monoxide concentration. In the case where the synthesis gas stream is introduced into the synthesis gas reactor with an O / C ratio higher than the O / C upper limit, the S / DG ratio can be increased in the case of a determined increase in the carbon monoxide concentration. The carbon monoxide concentration can be determined based on a computer simulation of an upstream synthesis gas formation process in which the synthesis gas is formed and / or based on an empirical value of the carbon monoxide concentration derived from a previous run of the upstream synthesis gas formation process. In a further development, the carbon monoxide concentration is determined by analyzing the raw synthesis gas from the upstream synthesis gas formation process and / or the synthesis gas stream entering the water-gas shift reactor and / or the transformed synthesis gas stream leaving the water-gas shift reactor, for example, by gas chromatography. When analyzing the shifted syngas stream exiting a water-gas shift reactor, the carbon monoxide concentration of the syngas stream entering the shift reactor may be determined by computer simulation of the water-gas shift reaction occurring in the shift reactor.

[0033] Reactor outlet temperature T 出口 Control may include adjusting the S / DG ratio based on the carbon monoxide concentration of the syngas stream at process startup, and optionally monitoring the carbon monoxide concentration thereafter while the process is running, and readjusting the S / DG ratio based on that monitoring.

[0034] In an advantageous embodiment, the control of the reactor outlet temperature comprises monitoring the outlet temperature by a temperature sensor during startup and / or during operation. If the process is operated within the lower limit of the O / C domain, an increase in the outlet temperature can be offset by reducing the S / DG ratio. If the process is operated within the upper limit of the O / C domain, an increase in the outlet temperature can be offset by increasing the S / DG ratio.

[0035] Can provide reference temperature T 参考 , which is less than or equal to T临界 A safety margin ΔT, that is, T 参考 =T 临界 –ΔT. T 参考 Can be used as the maximum temperature T 最大 , which must not be exceeded or only slightly exceeded, or is used as the target temperature T 目标 , where the S / DG ratio is adjusted to satisfy T 目标 . T 目标 Can be a reference variable for manual or automatic control. 参考 can be predetermined and held constant, or used as T 临界 and T 入口 and optionally additional process variables (such as carbon monoxide concentration x CO and / or S / DG ratio). 参考 can be calculated, for example, as T 参考 =T 临界 -A(T 临界 –T 入口 ), where A is a constant selected from the interval 0.1 to 0.2, for example. Once the monitored outlet temperature has risen to or above the reference temperature, the S / DG ratio can be adjusted to prevent exceeding T 临界 .

[0036] 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 that vary the flow rate of water added to the syngas. Monitoring the reactor outlet temperature involves adjusting T 出口 With T 参考 For comparison, T 参考 Can be used as T 最大 , as explained above.

[0037] In a further development, the control of the reactor outlet temperature is automated and implemented as a feedforward control (open loop) or a feedback control (closed loop). When implemented as a forward control, changes in the carbon monoxide concentration can be offset by reducing or increasing the S / DG ratio to keep the O / C ratio outside the critical intermediate range and to adjust T 出口 Keep at T 临界 or below T 临界 In feedback control, the reference temperature can be used as the target temperature T 目标 is provided, i.e. as a reference variable, and the reactor outlet temperature can be monitored and compared with T 目标 The S / DG ratio can be decreased or increased as a function of this comparison in order to keep the O / C ratio outside the critical intermediate range.

[0038] The corresponding comparison in automatic or manual control is to calculate T 参考 and T 出口 The deviation can be calculated as the difference T 参考 -T 出口 or T 出口 -T 参考 or ratio T 出口 / T 参考 or T 参考 / T 出口 , or is calculated to provide information about T 出口 How close is T 参考 and T 出口 is still lower than T 参考 Still higher than T 参考 Any other measure of information.

[0039] The subject process may include measuring a temperature T representing the outlet temperature of a water-gas shift reactor. 出口 The temperature representing the reactor outlet temperature is compared with the reference temperature T 参考 For comparison, the reference temperature T 参考 Can be used as the maximum temperature T 最大 Or as the target temperature T 目标 Provide. 参考 It can be advantageously selected to be greater than 0.9·T 临界 or greater than 0.95·T 临界 , and at most equal to T 临界 and preferably less than T 临界 . The process may further include changing the S / DG ratio in response to the results of the comparison. In a process in which the syngas stream is introduced into the water-gas shift reactor at an O / C ratio below an O / C lower limit, the S / DG ratio may decrease as the temperature representing the reactor outlet temperature increases above a target temperature. In a process in which the syngas stream is introduced into the water-gas shift reactor at an O / C ratio above an O / C upper limit, the S / DG ratio may increase as the temperature representing the reactor outlet temperature increases above a target temperature. The comparison and / or subsequent S / DG adjustment may be performed by an operator, or may be performed automatically if the process is performed under automatic control.

[0040] More than T 临界 It may be tolerated for a period of time, since metal dusting is not an instantaneous failure limit, but operation at or above the critical temperature for metal dusting will shorten the life of the metal material in contact with the hot syngas. Therefore, not every exceedance needs to be offset immediately. The S / DG ratio can be adjusted so that the outlet temperature T 出口 The critical temperature T is maintained for more than 80% or more than 90% of the operating time of the water-gas shift reactor. 临界or below the critical temperature T 临界 . Exceed T 临界 Less than 10% or less than 5%, i.e. T 临界 <T 出口 <1.1·T 临界 or T 临界 <T 出口 <1.05·T 临界 , may be tolerated for short periods of time of less than 20% or less than 10% of the operating time of the water-gas shift reactor. The higher the temperature exceeded, the earlier the S / DG ratio needs to be adjusted.

[0041] The raw synthesis gas may be formed in a synthesis gas 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. It may in particular 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 partially oxidized raw synthesis gas.

[0042] The process may include removing soot and / or particulate matter and / or sulfur and / or other contaminants from the syngas prior to reacting the syngas stream in a water-gas shift reactor. The removal may be performed by wet scrubbing in a scrubber arranged to receive at least a portion of the syngas from an upstream syngas forming reactor such as a POX reactor, wherein the water-gas shift reactor may be arranged 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.

[0043] The process may include an intermediate desulfurization step, particularly in the case of forming synthesis gas by partial oxidation of non-gaseous feedstocks (such as coal, biomass and / or hydrocarbon liquids). In embodiments where the carbonaceous feedstock for the synthesis gas formation process is a gas (such as natural gas, refinery tail gas, other gaseous hydrocarbons or mixtures thereof), desulfurization is preferably performed upstream of the synthesis gas formation process, and the formation process uses a desulfurized feed gas. However, even in the case where the carbonaceous feedstock for the synthesis gas formation process is a gas (such as natural gas, refinery tail gas, other gaseous hydrocarbons or mixtures thereof), desulfurization may be performed as an intermediate step between the primary formation process and the conversion 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 an optional intermediate desulfurization step, for example in the form of scrubber water.

[0044] When flowing through the respective scrubber, the syngas may absorb or release water depending on its water holding capacity. Thus, the scrubber may act as a water saturator. The amount of water absorbed in the respective scrubber may be influenced by adjusting the temperature that the syngas has at the inlet of the scrubber, which temperature may vary within the limits of the operating temperature of the respective scrubber. The hot syngas leaving the syngas forming reactor may be cooled in one or more coolers on the way to the scrubber to a temperature at which the syngas absorbs a certain amount of water when flowing through the scrubber, which temperature adjusts the water concentration of the syngas leaving the scrubber to the S / DG ratio of the shift reactor or close to the S / DG ratio of the shift reactor. Thus, adding water and adjusting the S / DG ratio may include, or even consist of, adjusting the temperature of the syngas on its way to the water-gas shift reactor.

[0045] When the syngas is fed to the water-gas shift reactor in the form of, for example, steam, at least a portion of the water added to adjust the S / DG ratio may be added directly to the syngas upstream of the water-gas shift reactor. In the direct addition, the water may be sprayed into the static mixer via one or more nozzles so that the directly added water completely enters the gas phase and is uniformly mixed with the syngas before the mixture enters the water-gas shift reactor.

[0046] Adjusting the S / DG ratio may include 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 portion or a third portion may be added directly only to adjust the S / DG ratio. Adjustment of the S / DG ratio may include or be achieved by all three of the above options.

[0047] The non-ferrous catalyst may comprise an oxide of zinc, aluminum and / or copper and one or more promoters. The catalyst may comprise a mixture of zinc alumina spinel and zinc oxide in its active form. The promoter may be selected from 1A group elements, Cu, Ti, Zr and rare earth metals and mixtures thereof, particularly selected from Na, K, Rb, Cs, Cu, Ti, Zr, rare earth elements and mixtures thereof. If the catalyst comprises an oxide 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 an alkali metal selected from the group consisting of Na, K, Rb, Cs and mixtures thereof as a promoter. The concentration of one or more alkali metals may be between 0.4 weight % and 8.0 weight % based on the weight of the oxidation catalyst.

[0048] A further subject of the invention is a system for enriching synthesis gas with hydrogen, comprising:

[0049] Fluid transport means for feeding and optionally processing the synthesis gas;

[0050] a water supply connected to the fluid delivery 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;

[0051] a water-gas shift reactor comprising a reactor inlet operably arranged to receive a stream of syngas from the fluid delivery means and a reactor outlet for shifted syngas;

[0052] A temperature sensor is used to sense the outlet temperature T of the water-gas shift reactor. 出口 and generating a temperature signal based on the sensed temperature; and

[0053] • One or more flow control devices capable of varying the total flow rate of water to the fluid delivery device to adjust the S / DG ratio so that the O / C ratio remains above an upper O / C limit or below a lower O / C limit.

[0054] The fluid transport device includes a pipeline for feeding synthesis gas, and may include a quenching zone (such as a quenching zone of a gasifier) ​​of an upstream synthesis gas forming reactor, and / or a separate quenching unit downstream of the synthesis gas forming reactor, and / or a scrubber for removing soot and / or particulate matter and / or sulfur and / or other pollutants, and / or one or more other synthesis gas processing devices. Desulfurization can be provided upstream of the synthesis gas forming reactor instead of or in addition to the optional desulfurization between the synthesis gas forming reactor and the water-gas shift reactor. The water supply device may include one or more water sources in liquid form and / or as steam. One or more flow control devices can be provided, for example, as a control valve and / or a pump and / or a compressor, which includes a combination of a pump or a compressor and a control valve.

[0055] The temperature sensor can sense the temperature of the transformed synthesis gas when or shortly after the transformed synthesis gas leaves the water-gas shift reactor or by convection contact at the downstream end of the reaction zone of the water-gas shift reactor. In contrast, the temperature sensor can measure the temperature of the components in the outlet pipe of the water-gas shift reactor or the transformed synthesis gas through which it leaves the reactor outlet. Regardless of the type and location of the measurement, the sensed temperature must allow reliable conclusions to be drawn about the actual temperature of the synthesis gas at the downstream end of the reaction zone and / or at the outlet of the reactor and / or at the pipe immediately following the reactor outlet. In this sense, the measured temperature represents the outlet temperature.

[0056] The system may include an output device that is arranged to receive a temperature signal from a temperature sensor and is configured to output an output signal that can be perceived by a system operator, the output signal representing the reactor outlet temperature. The output device may be formed by a visual output device and / or an audible alarm, or include a visual output device and / or an audible alarm. In response to the output signal, the system operator may then manipulate one or more of the one or more flow control devices to adjust the S / DG ratio so that the O / C ratio remains above an upper O / C limit or below a lower O / C limit. The output signal may indicate to the system operator that a reference temperature has been reached or just exceeded.

[0057] As an alternative to manual control or in addition to manual control, the system can provide automatic control based on a comparison of the measured temperature with a reference temperature (such as the target temperature described above with respect to the process). In such a further development, the system includes an electronic controller for controlling one or more flow control devices. The electronic controller can be configured to calculate a temperature deviation between the sensed temperature and the reference temperature. The electronic controller can also be configured to command one or more flow control devices to change the total flow rate of water in response to the calculated temperature deviation to adjust the S / DG ratio so that the O / C ratio remains above the upper O / C limit or below the lower O / C limit, thereby maintaining the outlet temperature at or below the reference temperature.

[0058] The present invention also relates to a system for enriching synthesis gas with hydrogen, wherein the system comprises:

[0059] Fluid transport means for feeding and optionally processing the synthesis gas;

[0060] a water supply connected to the fluid delivery 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;

[0061] a water-gas shift reactor comprising a reactor inlet operably arranged to receive a stream of syngas from the fluid delivery means and a reactor outlet for shifted syngas;

[0062] A gas analyzer for determining the carbon monoxide concentration X of the synthesis gas stream indirectly or directly with the aid of a computer simulation CO , and for generating a concentration signal representative of the determined carbon monoxide concentration; and

[0063] • One or more flow control devices capable of varying the total flow rate of water to the fluid delivery device to adjust the S / DG ratio so that the O / C ratio remains above an upper O / C limit or below a lower O / C limit.

[0064] The fluid transport device includes a pipeline for feeding synthesis gas, and may include a quenching zone (such as a quenching zone of a gasifier) ​​of an upstream synthesis gas forming reactor, and / or a separate quenching unit downstream of the synthesis gas forming reactor, and / or a scrubber for removing soot and / or particulate matter and / or sulfur and / or other pollutants, and / or one or more other synthesis gas processing devices. Desulfurization can be provided upstream of the synthesis gas forming reactor instead of or in addition to the optional desulfurization between the synthesis gas forming reactor and the water-gas shift reactor. The water supply device may include one or more water sources in liquid form and / or as steam. One or more flow control devices can be provided, for example, as a control valve and / or a pump and / or a compressor, which includes a combination of a pump or a compressor and a control valve.

[0065] A gas analyzer (such as a gas chromatograph) can be arranged between the upstream synthesis gas formation reactor and the water-gas shift reactor to analyze the composition of the synthesis gas flowing from the synthesis gas formation reactor to the water-gas shift reactor. For example, the gas analyzer can be arranged near the inlet of the water-gas shift reactor to analyze the composition of the synthesis gas stream that has been adjusted for the 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 converted synthesis gas. The carbon monoxide concentration of the synthesis gas 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 combination with the composition information derived from the gas analyzer to determine the carbon monoxide concentration of the synthesis gas stream.

[0066] The system may include an output device that is arranged to receive the concentration signal from the gas analyzer and is configured to output an output signal that can be perceived by a system operator, the output signal representing the carbon monoxide concentration of the synthesis gas stream entering the water-gas shift reactor. The output device may be formed by or include a visual output device. In response to the output signal, the system operator can then manipulate one or more of the one or more flow control devices to adjust the S / DG ratio so that the O / C ratio remains above the upper O / C limit or below the lower O / C limit.

[0067] As an alternative to manual control or in addition to manual control, the system may provide automatic control based on a concentration signal from a gas analyzer. In such a further development, the system includes an electronic controller for controlling one or more flow control devices in response to the concentration signal from the gas analyzer. The electronic controller may be configured to calculate, in response to the concentration signal from the gas analyzer, a flow rate as determined by the carbon monoxide concentration X.CO 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 O / C upper limit or below the calculated or selected O / C lower limit. The electronic controller may be configured to command one or more flow control devices to change the total flow rate of water to match the desired steam to dry gas molar ratio S / DG.

[0068] In embodiments where a gas analyzer is positioned downstream of a 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 performing a 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 combination with composition information derived from the gas analyzer. The computing device may be separate from and connected to an electronic controller unit for data transmission, or may be an integral part of the electronic controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The invention is explained below by way of example with reference to the attached drawings. The features disclosed therein, each individually and in any combination of features, advantageously develop the subject matter of the claims and the embodiments described above.

[0070] Figure 1 A system according to a first embodiment is shown and a process for enriching synthesis gas with hydrogen by high temperature water-gas shift conversion is demonstrated.

[0071] Figure 2 A system according to a second embodiment is shown and demonstrates a process for enriching syngas with hydrogen via high temperature water-gas shift conversion.

[0072] Figure 3 Shown is a graph of reactor outlet temperature versus steam to dry gas ratio for syngas streams having different carbon monoxide concentrations.

[0073] Figure 4 Shown is a graph of reactor outlet temperature versus oxygen to carbon ratio for the same syngas stream.

[0074] Figure 5 Shown is a graph of reactor outlet temperature versus oxygen to carbon ratio for syngas streams of equal composition at different feed pressures. DETAILED DESCRIPTION

[0075] The following detailed description provides preferred exemplary embodiments and is not intended to limit the scope, applicability or configuration of the present invention. Instead, the following detailed description of the preferred exemplary embodiments will provide a description of preferred exemplary embodiments that can implement the present invention to those skilled in the art, and it should be understood that various changes may be made to the function and arrangement of elements without departing from the scope of the present invention as defined by the claims.

[0076] As used herein, the articles "a" and "an" refer to one or more when applied to any feature in the embodiments of the present invention described in the specification and claims. The use of "a" and "an" does not limit the meaning to a single feature unless such limitation is specifically stated. The article "the" preceding a singular or plural noun or noun phrase denotes one specific particular feature or a plurality of specific particular features and may have a singular or plural meaning depending on the context in which it is used.

[0077] The adjective "any" means one, some, or all of any number.

[0078] 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 that at least one of the entities in the list includes any specific combination of the entities in the list.

[0079] 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 help refer to process steps and are not intended to indicate the order in which the claimed steps are performed, unless and only if such an order is specifically stated in the claims.

[0080] Figure 1 A first exemplary embodiment of a process and system according to the present invention is shown. In the process, a carbonaceous feed stream 1 is desulfurized in a desulfurization unit 2, for example, by hydrodesulfurization, including but not limited to a hydrodesulfurization catalyst and a desulfurization adsorbent. The feed stream 1 can be a gaseous feed stream. It can include natural gas as its main component or consist of natural gas. The desulfurized feed stream 3 is fed into a synthesis gas forming reactor 5 to produce a crude synthesis gas 6. The synthesis gas forming reactor 5 is a partial oxidation (POX) reactor. An oxygen-containing fuel gas 4, such as pure oxygen, air or oxygen-enriched air, is supplied in a substoichiometric amount to partially oxidize the carbonaceous components of the feed stream 3 and form a crude synthesis gas 6 containing hydrogen H2, carbon monoxide CO, carbon dioxide CO2 and possibly other components (such as nitrogen N2 and methane CH4).

[0081] The raw syngas 6 is fed to a high temperature water-gas shift (HTS) reactor 12 via a fluid transport device for feeding, conditioning and optionally treating the raw syngas 6, and then subjected to a high temperature water-gas shift reaction in the shift reactor 12. Conditioning may include cooling the syngas and / or adding water to the syngas, thereby adjusting 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 temperature and / or low temperature water-gas shift reactors.

[0082] The fluid transport device may include 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, as is preferred, high pressure steam 27 may be generated for export and / or on-site power generation. As shown in the figure, the cooler 7 may provide mixed cooling, wherein quench water 21 may be introduced into the syngas 6 for cooling and / or adjusting the S / DG ratio of the syngas stream.

[0083] At least a portion of the syngas 6 may be treated, or if cooled in an optional cooler 7, the cooled syngas 8 may be treated. The treatment may include removal of soot and / or particulate matter and / or sulfur and / or other contaminants. The fluid transport device may include a treatment section 9 operably arranged to receive at least a portion of the syngas 6 or the cooled syngas 8 to form a cleaned syngas 10. The treatment 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 form or in vapor form.

[0084] The desulfurized feed stream 3 typically enters the syngas forming reactor 5 at a temperature below 900°F (480°C). The raw syngas 6 leaves the reactor 5 at a much higher temperature, typically in the range of 2200°F to 2500°F (1200°C to 1370°C), and may advantageously be cooled by indirect heat exchange and / or direct cooling in a cooler 7 immediately downstream of the reactor 5 to a temperature below 1050°F (565°C) or below 950°F (510°C) or below 850°F (450°C), which are temperatures of concern with respect to metal dusting. If the processing section includes a wet scrubber such as scrubber 9a, the syngas 6 may advantageously be cooled between the reactor 5 and the scrubber to a temperature still high enough for the syngas to absorb moisture (water) as it flows through the scrubber. The processing section 9 may include a dry filter 9b to remove soot and / or particulate matter and / or sulfur and / or other contaminants. The dry filter 9b may replace the wet scrubber 9a or may be provided in addition. In case the process section 9 comprises a desulphurisation unit, it may replace the upstream desulphurisation unit 2 or may be provided in addition.

[0085] Water 23 in liquid form or in the form of vapor or steam can be added directly to the syngas, for example, injected directly into the feed line or sprayed in a spray device or introduced via a mixing device when the syngas flows through the fluid transport device. Water 23 can be added directly to, for example, the cleaned syngas 10 to form the syngas stream 11, which is subjected to the water-gas shift reaction in the HTS reactor 12. Before the syngas stream 11 enters the HTS reactor 12, the water 23 can be sprayed into the static mixer 23a via one or more nozzles so that the directly added water 23 completely enters the gas phase and is uniformly mixed with the syngas 10.

[0086] The system may include a water supply 20 for adding quench water 21 and / or scrubber water 22 and / or direct water 23. The water supply 20 may include one or more water sources and / or connections for introducing water and / or one or more connections to one or more coolers of the system. In the case where the system includes one or more coolers for cooling the syngas between the syngas forming reactor 5 and the HTS reactor 12 by indirect heat exchange, the water supply 20 may be operably configured to receive at least a portion of the steam produced by at least one of the one or more coolers. For example, the water supply 20 may be operably configured to receive at least a portion 28 of the steam 27 produced by the cooler 7, and be configured to supply at least a portion of the steam to the syngas, for example as quench water 21 and / or scrubber water 22 and / or direct water 23.

[0087] The cleaned and conditioned syngas stream 11 is introduced into the HTS reactor 12 to form a shifted syngas 13 having an increased H2 concentration. The syngas stream 11 enters the reactor 12 at the reactor inlet and leaves at the reactor outlet. In the HTS reactor 12, carbon monoxide and steam react under adiabatic conditions over a non-iron-based catalyst in a water-gas shift reaction.

[0088]

[0089] The catalyst may comprise an oxide of zinc, aluminum and / or copper and one or more promoters. The catalyst may conveniently comprise a mixture of zinc alumina spinel and zinc oxide in its active form. The promoter may be selected from 1A group elements, Cu, Ti, Zr and rare earth metals and mixtures thereof, particularly selected from Na, K, Rb, Cs, Cu, Ti, Zr, rare earth elements and mixtures thereof. If the catalyst comprises an oxide 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 an alkali metal selected from the group consisting of Na, K, Rb, Cs and mixtures thereof as a promoter. The concentration of one or more alkali metals may be between 0.4 wt % and 8.0 wt % based on the weight of the oxidized catalyst.

[0090] In at least some embodiments, such as when a large amount of steam or vapor must be added to the syngas 10, at least a portion of the syngas 10 can bypass the static mixer 23a and the HTS reactor 12. The bypassed portion of the syngas 10 can be cooled and can be recombined with the shifted syngas 13. Bypassing at least a portion of the syngas 10 can reduce the total amount of steam required.

[0091] The system may include a CO2 removal unit 14, which is operably arranged to receive at least a portion of the shifted syngas 13 and is configured to remove CO2 from the shifted syngas 13 and form a CO2-depleted syngas 15. The CO2 removal unit 14 can be configured as an adsorption unit comprising an adsorbent for selectively adsorbing CO2. The CO2 removed from the shifted syngas 13 can be released or transported to a CO2 capture site or captured on site. The system may also include a purification unit 16, which is operably arranged to receive at least a portion of the CO2-depleted syngas 15 and is configured to form a H2-rich product 17 and a H2-depleted tail gas 40.

[0092] The tail gas 40 comprising residual carbon monoxide and possibly CH4 and / or residual CO2, or a first portion 42 of the tail gas 40, may be supplied to the synthesis gas forming reactor 5 via a compressor 41. If upstream desulfurization is provided, the tail gas 40 or the tail gas portion 42 may be added to the feed stream 1 or the desulfurized feed stream 3.

[0093] The tail gas 40 or a second portion 43 of the tail gas 40 can be supplied to a fired heater 45 via a compressor 41 to be combusted with oxygen to generate heat energy and produce steam 29. The oxygen can be supplied in the form of compressed air 44. Natural gas can also be supplied to the heater 45 to be combusted with the tail gas 40 or the tail gas portion 43. The hot flue gas 47 from the heater 45 can be cooled by indirect heat exchange with water in a heat exchanger 46 to form steam 29. The steam 29 can be exported or expanded on site to generate electricity. As another option, in addition to or in place of the steam 28, the water supply 20 can be operably arranged to receive at least a portion of the steam 29.

[0094] Figure 2 A second exemplary embodiment of a process and system according to the present invention is shown. In this process, a carbonaceous feed stream 1 can be desulfurized in a desulfurization unit 2, for example, by hydrodesulfurization, including but not limited to a hydrodesulfurization catalyst and a desulfurization adsorbent. The feed stream 1 or the desulfurized feed stream 3 (if a desulfurization unit 2 is present) is fed into a synthesis gas forming reactor 5 to produce a crude synthesis gas 6. The feed stream 1 may contain coal, coke, heavy oil, asphalt sands, biomass, natural gas, or a mixture thereof. In principle, the feed stream 1 may consist of any hydrocarbon or a mixture of hydrocarbons. The synthesis gas forming reactor 5 may be a partial oxidation (POX) reactor, and an oxygen-containing fuel gas 4 (e.g., air) may be supplied to partially oxidize the carbonaceous components of the feed stream 3 and form a crude synthesis gas 6 containing hydrogen H2, carbon monoxide CO, carbon dioxide CO2, and possibly other components (such as nitrogen N2 and methane CH4).

[0095] The raw syngas 6 is fed to a high temperature water-gas shift (HTS) reactor 12 via a fluid transport device for feeding, conditioning and optionally treating the raw syngas 6, and then subjected to a 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.

[0096] Quenching water 21 may be injected into at least a portion of the raw synthesis gas 6 from the synthesis gas forming reactor 5 in a quenching zone 18 of the fluid transport device. The quenching zone 18 may be arranged downstream of the reactor 5 or integrated into the reactor 5. In particular, quenching may be performed if the feed stream 1 consists of coal and / or biomass. If the feed stream 1 is a gas (such as natural gas), the raw synthesis gas 6 may be quenched, but is usually not quenched.

[0097] At least a portion of the syngas 6, or if quenched, the quenched syngas 8, may be treated. The treatment may include removing soot, particulate matter, sulfur and / or other contaminants from at least a portion of the syngas 6 or the quenched syngas 8 in a scrubber 19 of a fluid transport device to form a clean 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 form or in vapor form. In the case where the scrubber 19 is a desulfurization unit, it may replace the upstream desulfurization unit 2. The upstream desulfurization unit 2 may replace the intermediate desulfurization, or may be provided in addition. A dry filter or a syngas desulfurization reactor / sorbent vessel may also replace the wet scrubber 19, or may be provided in addition.

[0098] Water 23 in liquid form or in steam form can be added directly to the syngas, for example, injected directly into the feed line or sprayed in a spray device, or introduced via a mixing device as it flows through a fluid transport device. Water 23 can be added directly to, for example, clean and optionally quenched syngas 10 to form a syngas stream 11 that is subjected to a water-gas shift reaction in an HTS reactor 12. Before the syngas stream 11 enters the HTS reactor 12, the water 23 can be sprayed into a static mixer 23a via one or more nozzles so that the directly added water 23 completely enters the gas phase and is uniformly mixed with the syngas 10.

[0099] The system may include a water supply 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.

[0100] The cleaned and conditioned syngas stream 11 is introduced into the HTS reactor 12 to form a shifted syngas 13 having an increased H2 concentration. The syngas stream 11 enters the reactor 12 at the reactor inlet and exits at the reactor outlet. In the HTS reactor 12, carbon monoxide and steam react in a water-gas shift reaction over a non-iron-based catalyst under adiabatic conditions, as also described above with respect to the first exemplary embodiment.

[0101] The system may also include a CO2 removal unit, a purification unit, and a fired heater, each operably arranged and configured as described with respect to the first exemplary embodiment.

[0102] In any embodiment of the present invention, the shift reaction may be carried out at a pressure of 10 bara or more, preferably 65 bara or more. It may be carried out at a pressure of up to 100 bara or even higher.

[0103] Due to the exothermic nature of the water-gas shift reaction, the temperature of the reactants and products increases along the length of the HTS reactor 10 from the inlet temperature T at the reactor inlet to the 入口 The outlet temperature T of the reactor is increased to 出口 In many applications, T 入口 270°C or higher, and possibly up to 400°C, with inlet temperatures below 370°C or below 360°C being preferred. Without proper control, outlet temperatures may reach 900°F (480°C) or 950°F (510°C) or 1050°F (565°C) or even higher.

[0104] These high temperatures, combined with residual CO in the outlet stream, may exceed recommended limits for reactor components and / or piping near or after the reactor outlet, particularly for the first water-gas shift, i.e., HTS, reactor. Such limits may be the result of metallurgical and / or catalyst degradation considerations. It is desirable to maintain reactor components and / or downstream piping below the critical temperature T 临界 A temperature with a safety margin (i.e., the temperature of concern). For metallurgical considerations (such as metal dusting corrosion), 1050°F (565°C) can be considered the critical temperature T 临界 To reduce the risk of metal dusting, 950°F (510°C) may be selected alternatively. More conservatively, 850°F (450°C) may be selected as the critical temperature T 临界 .

[0105] 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. Check the outlet temperature T 出口 How it depends on the carbon monoxide concentration and water concentration of the synthesis gas stream 11, it can be seen that for a given S / DG ratio, the increase in carbon monoxide concentration is proportional to T 出口 For a given carbon monoxide concentration, the outlet temperature initially increases with increasing water concentration and, after exceeding the maximum temperature, decreases again with further increases in water concentration.

[0106] Figure 3 The reactor outlet temperature T of the synthesis gas stream 11 with different carbon monoxide concentrations is shown. 出口 versus the S / DG ratio, and Figure 4 shows the T of the same synthesis gas flow 出口Graph versus O / C ratio. The effect of increasing carbon monoxide concentration was investigated by computational process simulation. Temperature profiles for seven examples of synthesis gas streams containing 15 mol %, 27 mol %, 29 mol %, 31 mol %, 33.5 mol %, 42 mol % and 51 mol % carbon monoxide, respectively, are shown, each on a dry basis. Carbon monoxide concentration is the main parameter of variation. The critical temperature T 临界 is drawn as a horizontal dashed line. In this example, the critical temperature T 临界 850°F (450°C) was conservatively chosen.

[0107] Figure 5 The T values ​​of three examples of the same composition at feed pressures of 10 bar, 67 bar and 100 bar are shown. 出口 The graph is plotted against the O / C ratio. It can be seen that the feed pressure has a significant effect on T 出口 Has a very weak effect.

[0108] The dry gas compositions in mol % for three examples are shown in the table below.

[0109] <![CDATA[H2]]> CO <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[N2]]> Ar Example 1 63.6 27.0 8.5 0.1 0.7 0.1 Example 2 63.3 31.0 4.6 0.3 0.7 0.1 Example 3 62.8 33.5 2.2 0.7 0.7 0.1

[0110] The figure shows that the outlet temperature T 出口 As the CO concentration increases, the S / DG ratio and the O / C ratio increase. However, when the CO concentration continues to increase beyond 27 mol%, the optimal ranges of the S / DG ratio and the O / C ratio bifurcate into two separate domains and an intermediate range, which is undesirable because of the increased rate of metal dusting. The corresponding temperature curve T 出口 (S / DG) or T 出口 (O / C) and T 临界 Intermediate ranges are depicted from the favorable lower domain limit and the favorable upper domain limit at the two points where the horizontal lines of intersect. For Example 2, ie a synthesis gas stream with 31 mol % CO, corresponding boundary lines are drawn.

[0111] For the synthesis gas stream of Example 2 having a CO concentration of 31 mol %, favorable conditions in terms of metal dust formation result if the following ratios are maintained:

[0112] O / C<2.07 or O / C>3.7

[0113] S / DG<0.34 or S / DG>0.91

[0114] For the synthesis gas stream of Example 3 having a CO concentration of 33.5 mol %, favorable conditions in terms of metal dust formation result if the following ratios are maintained:

[0115] O / C < 1.69 or O / C > 4.25

[0116] S / DG < 0.25 or S / DG > 1.19

[0117] The process simulation (for which the examples are representative samples only) shows that for a synthesis gas stream containing up to 29 mol% of carbon dioxide on a dry basis, if the shift reaction is carried out in the lower limit of the S / DG domain, i.e. if the S / DG ratio is kept below 0.50, metal dusting of metal pipes and other metal parts can be prevented or at least delayed. This keeps the O / C ratio below 2.5, which marks the lower limit of the intermediate range for 29 mol% CO. Adjusting the S / DG ratio to even lower values ​​allows further increases in carbon monoxide concentrations. For example, keeping the S / DG ratio below 0.34 allows an increase in carbon monoxide concentration to up to 31 mol% on a dry basis. For example, keeping the S / DG ratio below 0.25 allows an increase in carbon monoxide concentration to up to 33.5 mol% on a dry basis. Within the lower limits of the O / C and S / DG domains, the relationship between the reduction of the S / DG ratio and the O / C ratio and the corresponding increase in the allowed carbon dioxide concentration is not linear. Any further increase in carbon monoxide concentration can be compensated by an even smaller decrease in the S / DG and O / C ratios.

[0118] The shift reaction can alternatively be carried out in the upper limit of the domain. For carbon monoxide concentrations up to 29 mol% on a dry basis, if the S / DG ratio is kept above 0.67, metal dusting of metal pipes and other metal parts can be prevented or at least delayed. This keeps the O / C ratio above 3.0, which marks the upper limit of the intermediate range for 29 mol% CO. Adjusting the S / DG ratio to even higher values ​​allows for increased carbon monoxide concentrations. For example, keeping the S / DG ratio above 0.91 allows for an increase in carbon monoxide concentration to up to 31 mol% on a dry basis. For example, keeping the S / DG ratio above 1.19 allows for an increase in carbon monoxide concentration to up to 33.5 mol% on a dry basis.

[0119] In order to prevent or at least delay metal dusting, T can be controlled by adding water in a suitably adjusted amount to the syngas as it flows through the fluid delivery device to the shift reactor 10. 出口 To keep at T 临界 or below T 临界. Water can be added in a metered amount (i.e., a metered total feed rate) to adjust the S / DG ratio, and thereby the O / C ratio, to remain below a predetermined O / C lower limit or above a predetermined O / C upper limit. For a synthesis gas stream 11 having a carbon monoxide concentration greater than 15 mol % or greater than 20 mol %, a value of 2.5 can be selected as the O / C lower limit, and a value of 3.0 can be selected as the O / C upper limit. A synthesis gas stream having a carbon monoxide concentration greater than 30 mol % can be reacted under leaner steam conditions within the O / C domain lower limit, or under richer steam conditions within the domain upper limit, because the undesirable O / C intermediate range widens with increasing carbon monoxide concentration. Reducing the O / C lower limit to 2.07 or 2.0 or 1.69 or 1.6 or lower allows a synthesis gas stream having a carbon monoxide concentration greater than 30 mol % to react. Furthermore, increasing the upper O / C limit to 3.7 or 4.25 or 5.0 or higher allows for the reaction of syngas streams having carbon monoxide concentrations greater than 30 mol%.

[0120] The system of any embodiment may accordingly include one or more flow control devices, which are capable of changing the total flow rate of water to the fluid delivery device to adjust the S / DG ratio so that the O / C ratio remains above the upper limit of O / C or below the lower limit of O / C. The corresponding flow control device can be provided as a flow control valve. For example, if present, a flow control device 24 can be arranged in the process of supplying quenching water 21 to the quenching zone 5 to increase or decrease the flow rate of quenching water 21 for adjusting the S / DG ratio. As an alternative or in addition, if there is a scrubber, a flow control device 25 can be arranged in the supply of washing water 22 to increase or decrease the flow rate of washing water 21 for adjusting the S / DG ratio. In order to adjust the S / DG ratio, the supply for direct water addition is particularly suitable because changing the flow rate of direct water 23 will not affect any other sub-processes, such as washing. Therefore, a flow control device 26 can be set in the feed of the directly added water 23 to increase or decrease the flow rate of direct water 23 for adjusting the S / DG ratio. Any of the above control devices may be used as the sole control device for adjusting the S / DG ratio, or in combination with one or more other corresponding control devices.

[0121] The total flow rate of water added to the syngas, and therefore the S / DG ratio, can be adjusted so that the O / C ratio is brought to the lower or upper limits of the domain during the initial operating phase of the system and can be kept constant thereafter. 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 by adjusting the S / DG ratio as described above to remain at or below the critical temperature. As the process continues, if the reactor outlet temperature T 出口 Increase to the predetermined reference temperature T参考 , it can be adjusted, where T 入口 <T 参考 ≤T 临界 Once this occurs, the total flow of water is reduced or increased by operating one or more flow control devices to maintain the O / C ratio within the corresponding O / C domain. The following relationship may hold:

[0122] T 参考 >T 入口 +0.7·(T 临界 –T 入口 ) or T 参考 >T 入口 +0.8·(T 临界 –T 入口 ).

[0123] T 参考 Less than or equal to T 临界 A safety margin. Conveniently,

[0124] T 参考 <T 临界 -0.05·(T 临界 –T 入口 ) or T 参考 <T 临界 -0.1·(T 临界 –T 入口 ).

[0125] Based on experience, a safety margin of 10°C or higher and / or 30°C or lower may be selected.

[0126] Alternatively, the carbon monoxide concentration X of the synthesis gas stream 11 entering the shift reactor 12 may be calculated based on CO To control the reactor outlet temperature. CO It can be determined chromatographically during the process, or data from a comparable previous process can be used. Depending on the O / C domain in which the process is carried out, the corresponding O / C limit can be used as X CO The total carbon and oxygen concentrations of the dry gas fraction in the synthesis gas stream 11 may be calculated as a function of, or provided in a table in which increasing carbon monoxide concentrations are assigned an O / C lower limit and / or an O / C upper limit. From the total carbon concentration and oxygen concentration of the dry gas fraction in the synthesis gas stream 11, the S / DG ratio required to keep the O / C ratio below or above the corresponding O / C limit may be calculated, and the total flow rate of added water may then be adjusted accordingly. The total carbon and oxygen concentrations of the dry gas fraction may be determined chromatographically during the process, or data from a comparable previous process may be used.

[0127] Both control methods can be combined: During the start-up phase of the process, the corresponding 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 keep the O / C ratio outside the undesirable intermediate range, thereby controlling the reactor outlet temperature. Once the process has reached steady state, the reactor outlet temperature is monitored, compared with the above-mentioned maximum temperature, and the S / DG ratio is adjusted if necessary to keep the O / C ratio below the lower O / C limit or above the upper O / C limit.

[0128] One or more sensors may be provided, such as Figure 2 , such as a flow meter 32, for determining the flow rate Δm / Δt of the syngas fed to the shift reactor 12, and generating a flow rate signal based on the determination. The flow meter 31 may be disposed at any location between the syngas forming reactor 5 and the HTS reactor 12. In an exemplary embodiment, the flow meter 31 is positioned to measure the flow rate of the syngas before adding water.

[0129] The system may include a temperature sensor 32 for sensing an inlet temperature T representing the syngas stream 11 entering the shift reactor 12. 入口 The temperature of the shift reactor 12 is sensed by the temperature sensor 32, and an inlet temperature signal is generated based on the sensed temperature. The temperature sensor 32 can directly sense the inlet temperature of the syngas stream 11 in countercurrent contact, or indirectly sense the inlet temperature by sensing the temperature of the feed line or reactor wall or reactor component near the inlet of the shift reactor 12.

[0130] In particular, in order to control the reactor outlet temperature, the system may include a temperature sensor 33 for sensing an outlet temperature T representing the syngas stream 13 leaving the shift reactor 12. 出口 The temperature sensor 33 may sense the temperature of the shifted syngas 13 in convective contact with the reactor outlet directly, such as when still in the reactor 12 or leaving the reactor 12 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 feed line or a reactor wall or reactor component near the outlet of the shift reactor 12.

[0131] The system may include a gas analyzer 34, such as a gas chromatograph, for determining the composition of the shifted syngas 13 leaving the shift reactor 12 or the syngas stream 11 entering the reactor 12. The gas analyzer 34 may be configured to determine the concentration of a major component of the shifted syngas 13 or syngas stream 11, such as a carbon monoxide concentration X. CO 、Carbon dioxide concentration X CO2 , Hydrogen concentration X H2 and water concentration X H2OThe gas analyzer 34 may be configured to determine the concentration of other components that may be present, such as methane and / or nitrogen. In principle, the gas analyzer 34 may be configured to determine only the carbon monoxide concentration X. CO If the gas analyzer 34 is positioned downstream of the shift reactor 12, as Figure 2 As shown in , the carbon monoxide concentration of the synthesis gas stream 11 entering the shift reactor 12 can be determined by back-calculation from the composition of the shifted synthesis gas 13 in a computer-aided simulation of the reactions occurring in the shift reactor 12. The gas analyzer 34 (if present) can be configured to generate a concentration signal representative of the corresponding gas component, in particular a concentration signal representative of the carbon monoxide concentration.

[0132] In further developments, automated control can be provided, e.g. Figure 2 The system may include an electronic controller 30 for controlling one or more flow control devices 24 to 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 to 26" means controlling one or more (including all) existing flow control devices to control the amount of water added to form the synthesis gas stream 11.

[0133] The electronic controller 30 may be configured to calculate the sensed temperature and the reference temperature T 参考 The temperature deviation between T and , which temperature deviation can be stored in the data memory of the controller 30 or provided by an external source. 参考 Can be kept constant or used as T 临界 and one or more process variables (such as T 入口 and / or X CO The electronic controller 30 may be configured to calculate the flow rate reduction or flow rate increase required to bring the outlet temperature closer to the target temperature, or to select such flow rate reduction or flow rate increase from a predetermined table that assigns corresponding flow rate reductions or flow rate increases to different values ​​of the temperature deviation. The electronic controller 30, if present, is configured to command one or more flow control devices 24 to 26 to change 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 to adjust the S / DG ratio so that if the shift reaction is carried out in the lower limit of the O / C domain, the O / C ratio remains below the lower limit of the O / C domain, and if the shift reaction is carried out in the upper limit of the O / C domain, the O / C ratio remains above the upper limit of the O / C domain.

[0134] Instead of using the reactor outlet temperature as a controlled variable or in addition to using the reactor outlet temperature as a controlled variable, the concentration signal from the gas analyzer 34 can be used to control the reactor outlet temperature. The electronic controller 30 can control one or more of the one or more flow control devices 24 to 26 in response to the concentration signal from the gas analyzer 34. The electronic controller 30 can be configured to calculate the carbon monoxide concentration X as determined in response to the concentration signal from the gas analyzer 34 and according to the O / C range in which the HTS reactor 12 operates. CO The electronic controller 30 may be configured to select or calculate the S / DG ratio required to keep the O / C ratio above the upper O / C limit or below the lower O / C limit. The electronic controller 30 may also be configured to command one or more flow control devices 24 to 26 to change the total flow rate of water to match the desired S / DG ratio.

[0135] The system of the first exemplary embodiment may include one or more sensors, including all sensors shown and described in conjunction with the second exemplary embodiment, and may also include an electronic controller 30. 出口 As far as control is concerned, the process of the first exemplary embodiment may be performed as described with respect to the second exemplary embodiment.

[0136] In the basic embodiment where the S / DG ratio is adjusted manually, no electronic controller is required. The electronic controller 30 is an optional component of the system and process. In the basic embodiment, the controller 30 can be replaced by an output device (such as an optical display) for monitoring process variables, such as the outlet temperature T 出口 and / or inlet temperature T 入口 and / or carbon monoxide concentration X CO The operator can respond to the output as described above to maintain the reactor outlet temperature below the critical temperature T 临界 .

Claims

1. A method for enriching synthesis gas with hydrogen, the method comprising: adding H2O 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; The synthesis gas stream is introduced into a water-gas shift reactor, the synthesis gas stream having an inlet temperature T 入口 ; The synthesis gas stream is reacted in the water-gas shift reactor in the presence of a non-iron-based catalyst to produce a 出口 of the shifted synthesis gas; as well as The outlet temperature T is controlled by adjusting the S / DG ratio to keep the O / C ratio below the O / C lower limit or above the O / C upper limit. 出口 To maintain at or below the critical temperature T 临界 , or lowered to the critical temperature T 临界 or below the critical temperature T 临界 .

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

3. The method according to claim 1, wherein the critical temperature T 临界 It is 1050℉(565℃).

4. The method according to claim 1, wherein the corresponding O / C limit value is the carbon monoxide concentration of the synthesis gas stream and / or the inlet temperature T 入口 function to select or calculate.

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

0.

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

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

8. The process of claim 1 wherein the syngas stream has a carbon monoxide concentration greater than 15 mole percent on a dry basis.

9. The process of claim 1, wherein the syngas stream is introduced into the water-gas shift reactor at a carbon monoxide concentration greater than 15 mol% and a S / DG ratio less than 0.

5.

10. The process of claim 1, wherein the syngas stream is introduced into the reactor at a carbon monoxide concentration greater than 15 mol% and a S / DG ratio greater than 0.

67.

11. The method according to claim 1, further comprising: The outlet temperature T of the water-gas shift reactor is measured 出口 Temperature; Provide reference temperature T 参考 , the reference temperature is equal to or less than the critical temperature T 临界 a safety margin and will represent the outlet temperature T 出口 The temperature and the reference temperature T 参考 Make comparisons; and changing the S / DG ratio in response to a result of the comparison; wherein the synthesis gas stream is introduced into the synthesis gas reactor at an O / C ratio below the O / C lower limit, and if the outlet temperature T 出口 The temperature rises above the reference temperature T 参考 , then the S / DG ratio decreases; or wherein the synthesis gas stream is introduced into the synthesis gas reactor at an O / C ratio higher than the O / C upper limit, and if the outlet temperature T 出口 The temperature rises above the reference temperature T 参考 , then the S / DG ratio increases.

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

13. The method according to claim 1, further comprising: determining a carbon monoxide concentration in the synthesis gas stream; as well as varying the S / DG ratio based on the determined carbon monoxide concentration; wherein the synthesis gas stream is introduced into the synthesis gas reactor at an O / C ratio below the O / C lower limit and the determined increase in carbon monoxide concentration is offset by reducing the S / DG ratio; or The synthesis gas stream is introduced into the synthesis gas reactor at an O / C ratio above the O / C upper limit, and the determined increase in carbon monoxide concentration is offset by increasing the S / DG ratio.

14. A method according to claim 1, wherein while the synthesis gas is fed into the water-gas shift reactor, at least a portion of water is added directly to the synthesis gas upstream of the water-gas shift reactor, and / or at least a portion of the water is added by quenching and / or washing with water.

15. The process of claim 1, wherein the non-iron based catalyst in its active form comprises a mixture of zinc alumina 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. The method of claim 16, wherein the non-iron based catalyst has a Zn / Al molar ratio between 0.5 and 1.0, and a concentration of alkali metal selected from the group consisting of Na, K, Rb, Cs, and mixtures thereof between 0.4 wt. % and 8.0 wt. % based on the weight of the oxidized catalyst.

17. The method according to claim 1, wherein T 入口 In the range of 270°C to 400°C.

18. A method for enriching synthesis gas with hydrogen, the method comprising: adding H2O 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; The synthesis gas stream is introduced into a water-gas shift reactor, the synthesis gas stream having an inlet temperature T between 270°C and 400°C. 入口 ; The synthesis gas stream is reacted in the water-gas shift reactor in the presence of a non-iron-based catalyst to produce a 出口 of the shifted synthesis gas; The measured outlet temperature T 出口 Temperature; Determine the carbon monoxide concentration X of the synthesis gas stream CO ;as well as The outlet temperature T is controlled by adjusting the S / DG ratio to keep the O / C ratio below the O / C lower limit or above the O / C upper limit. 出口 To maintain at or below 1050°F (565°C); Wherein the O / C lower limit and the O / C upper limit are determined as T 入口 and / or X CO function.

19. A system for enriching synthesis gas with hydrogen, the system comprising: a fluid transport device for feeding and optionally processing the synthesis gas; a water supply connected to the fluid delivery device to add water to the synthesis gas to form a synthesis gas stream including 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 comprising a reactor inlet operably arranged to receive said syngas stream from said fluid delivery means and a reactor outlet for shifted syngas; A temperature sensor is used to sense the outlet temperature T of the water-gas shift reactor. 出口 a temperature of the vehicle and generating a temperature signal based on the sensed temperature; as well as One or more flow control devices capable of varying the total flow rate of water to the fluid delivery device to adjust the S / DG ratio such that the O / C ratio remains above an upper O / C limit or below a lower O / C limit.

20. The system according to claim 19, further comprising a gas analyzer for determining the carbon monoxide concentration X of the synthesis gas stream. CO , and is used to generate a concentration signal representing the determined carbon monoxide concentration.

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