Method for supplying oxygen-rich gas to an oxygen-consuming process

Abstract

The present invention provides a method for supplying oxygen-rich gas to an oxygen-consuming step, which comprises supplying an anode-side feed gas containing CO2 to the anode side of a solid oxide electrolysis cell to generate oxygen-rich gas with a low nitrogen content, and generating oxygen on the anode side of the solid oxide electrolysis cell. In this manner, an anode-side product gas containing at least a portion of the oxygen-rich gas is formed. The oxygen-rich gas has a low nitrogen content, and the temperature of the oxygen-rich gas exiting the solid oxide electrolysis cell is between 600 and 1000°C. This method has several advantages, primarily in terms of energy conservation.

Description

[Technical Field]

[0001] The present invention relates to a method for supplying oxygen-rich gas (oxygen-enriched gas) to an oxygen-consuming process, by supplying an anode side feed gas containing CO to the anode side of an operating solid oxide electrolysis cell (SOEC) to produce oxygen-rich gas with a reduced nitrogen content. The present invention also relates to a solid oxide electrolysis cell supplied with a feed gas containing CO, the anode side of the cell being in fluid communication with an oxygen-consuming process. [Background technology]

[0002] Oxyfuel combustion is a process in which hydrocarbon fuels are burned in a nitrogen-poor environment, typically in a stream of nearly pure oxygen or a mixture of oxygen and carbon dioxide. The primary purpose of oxyfuel combustion, such as in coal-fired power plants, is to produce flue gases with very high concentrations of CO2 and steam, allowing for the separation and capture of CO2 from the flue gas while avoiding the costly separation of CO2 from the nitrogen in the gas. Importantly, even with oxyfuel combustion, the flue gas still contains impurities such as residual nitrogen, unburned oxygen, sulfur dioxide, nitrogen oxides, and particulate matter. Many of these impurities must be removed to produce carbon dioxide of a purity suitable for carbon capture and storage or downstream uses.

[0003] Oxyfuel combustion for CO2 capture has four main components: 1) an air separation unit (ASU), which provides an oxygen-rich oxide stream for combustion; 2) a boiler or gas turbine, where fuel is burned to generate heat; 3) an exhaust gas treatment unit, where undesirable materials such as ash, sulfur, and most of the nitrogen oxides are removed from the exhaust gas; and 4) a CO2 processing unit (CPU), where final purification of the CO2 occurs for transport, storage, and / or utilization.

[0004] When hydrocarbon fuels are burned in pure oxygen, the flame temperature is much higher than when they are burned in air. Peak temperatures can reach 2500 °C, compared to 1700 °C for conventional supercritical boilers. Current technology limits combustion temperatures to approximately 1300–1400 °C for typical gas turbine cycles and approximately 1900 °C for oxy-fuel coal-fired boilers. To mitigate material corrosion issues that ultimately lead to boiler failure, a portion of the CO2-rich flue gas leaving the boiler is typically mixed with an oxygen-rich stream fed to the burner. This dilutes the oxygen and reduces the flame temperature to that of conventional air-blown plants.

[0005] For pulverized coal combustion, pilot-scale tests by Croiset and Thambimuthu reported that when the feed gas used for oxy-fuel combustion was approximately 35 vol% O2 and 65 vol% dry recycled CO2 (see 21 vol% O2 in air, balance N2), gas flame temperatures and heat capacities comparable to fuel combustion in air were generated.

[0006] Another important aspect of oxyfuel power plants is the reduction of nitrogen monoxide (NO), which contributes to the formation of undesirable HNO during exhaust gas compression in the CO2 treatment unit. x It is also important to understand the behavior of NOx. The generation pathways of NOx include: 1) thermal NO x 2) Rapid NO generation x 3) NO production of fuel nitrogen x Three main pathways for the conversion of N2 to NO2 are known. In oxy-fuel combustion, N2 concentration is very low due to the absence of N2 in air, and thermal NO2 x Generation pathway and prompt NO x The production pathway is often negligible. Therefore, NO from fuel nitrogen x NO production is the most important pathway in boilers using oxy-fuel combustion. x Approximately 95% of the carbon dioxide is nitric oxide (NO), with the remainder being nitrogen dioxide (NO2) and smaller amounts of nitrogen dioxide (N2O) and other nitrogen oxides. [Prior art documents] [Patent documents]

[0007] [Non-Patent Document 1] Joule 2, 1573-1594 (2018) Summary of the Invention [Problem to be solved by the invention]

[0008] Oxygen-rich streams are also beneficial in oxy-fuel calciners, or oxygen calciners. Indeed, oxy-fuel calciners are gaining wider interest due to their potential use in direct air capture plants, including, for example, calcium loops. For example, David W. Keith et al. describe a process for capturing CO2 from the atmosphere (Joule 2, 1573-1594 (2018)). More specifically, a 1-megaton-per-year CO2 plant for direct air capture of CO2 from the atmosphere is described. The plant's process chemistry is based on two loops: an alkaline loop (CO2 + KOH → K2CO3 → KOH) and a calcium loop (CaCO3 → CaO + CO2 → Ca(OH)2 → CaCO3). CO2 is captured by reacting with KOH to yield K2CO3. This K2CO3 is then reacted with Ca(OH)2 to regenerate KOH and yield CaCO3. The latter is then calcined in an oxy-fuel calciner to release CO2 and regenerate Ca species. Importantly, calcination must be carried out in a nitrogen-poor atmosphere because CO2 and nitrogen (released during calcination) are difficult to separate once mixed. Specifically, calcium carbonate (CaCO3) produced in the calcium loop is directed to a calciner, where the solid material is regenerated into CaO and CO2, which is then discharged from the reactor for purification and compression. The calciner requires an additional heat source to raise its temperature to around 900°C, which is necessary to generate the heat required for the endothermic calcination reaction. The most obvious way to generate this heat is through oxy-fuel combustion, which, as mentioned above, produces a CO2-rich flue gas. Again, an ASU is required for oxy-fuel combustion. The efficiency of an oxygen calciner depends on the oxygen concentration of the oxygen-rich stream used for calcination; the higher the oxygen concentration, the higher the efficiency. Higher oxygen concentration improves efficiency by reducing the total amount of gas fed to the furnace, thereby reducing the furnace's heat demand. Less heat means less fuel input and therefore a lower oxygen flow rate. Plant downsizing is significant, reducing plant investment costs, especially for the calcium looping process, where the calciner is an adiabatic furnace.

[0009] In modern oxy-fuel combustion and oxy-sinter plants, ASUs, typically low-temperature ASUs, are used to supply an oxygen-rich gas stream to the boiler or calciner chamber. ASUs are very expensive (in terms of capital expenditure (CAPEX) and operating expenditure (OPEX)). ASUs consume approximately 225 kWh of energy per ton of O2 produced, making them one of the most expensive pieces of equipment in oxy-fuel combustion and oxy-sinter plants. The objective of the present invention is to provide an alternative method for supplying oxygen-rich gas to oxygen-consuming processes, such as the oxy-fuel combustion and oxy-sinter processes mentioned above. More specifically, the present invention proposes supplying an anode side feed gas containing CO2 to the anode side of an operating solid oxide electrolysis cell (SOEC), thereby obtaining an oxygen-rich anode side product gas and producing an oxygen-rich stream with a reduced nitrogen content. [Means for solving the problem]

[0010] Solid oxide electrolysis cells (SOECs) can be used to electrochemically reduce HO to H, CO to CO, or a combination of HO and CO to syngas (H and CO). This conversion occurs on the cathode (fuel) side of the solid oxide electrolysis cell. On the anode (oxy) side of the cell, oxygen is electrochemically produced. In the context of the present invention, the term "electrochemically produced" refers to a process in which a chemical species is formed via an electrochemical process (i.e., a chemical process involving electron transfer). Such a process can be, for example, the oxygen evolution reaction (O 2- =O2+4e - ), water reduction reaction (H2O + 2e - =H2+O 2- ) and carbon dioxide reduction reaction (CO2 + 2e - =CO+O 2- ) The water gas shift reaction or reverse water gas shift reaction does not involve an electrochemical step.

[0011] In the context of the present invention, the terms "stream," "gas," and "gas stream" are used interchangeably.

[0012] In the context of the present invention, the term "at least a portion" of a gas stream is understood to refer to either the entire gas stream or a portion of the stream. The gas stream may simply be divided into fractions of the same composition. This does not imply separation of the gas components. For example, this may be relevant when it is desired to recycle a portion of the gas stream to a solid oxide electrolysis cell. The fraction fed to the oxygen / H2 / CO consuming step may be, for example, between 5% and, as an upper limit, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the oxygen-rich gas or H2 and / or CO2-rich gas.

[0013] The cathode side feed gas stream is also referred to as the fuel feed, and the anode side feed gas stream is also referred to as the flush feed.

[0014] Unless otherwise specified, the proportion of the gas phase is vol% (volume%).

[0015] When a cathode feed gas containing HO is supplied to the cathode side of an operating SOEC, at least a portion of the HO is electrochemically reduced to H (i.e., H is electrochemically produced), thereby forming a hydrogen-rich cathode product gas. In the context of the present invention, the term "X-rich" is understood to mean "the concentration of X in the stream is increased compared to the concentration of X in the corresponding feed gas." In other words, the hydrogen-rich cathode gas stream (exiting the electrolysis cell) has a higher concentration of hydrogen than the cathode feed gas (entering the solid oxide electrolysis cell). Similarly, when a cathode feed gas containing CO is supplied to the cathode side of an operating SOEC, at least a portion of the CO is electrochemically reduced to CO (i.e., CO is electrochemically produced), thereby forming a CO-rich cathode product gas. Furthermore, when a cathode feed gas containing a mixture of HO and CO is fed to the cathode of an SOEC, at least one of the HO and / or CO is electrochemically reduced to form a cathode product gas rich in hydrogen and CO. Similarly, an O-rich anode gas stream (exiting the electrolysis cell) will have a higher O concentration than the anode feed gas stream (entering the solid oxide electrolysis cell). It should be noted that, by this definition, a 10% O, 90% CO anode product gas stream can be considered O-rich if the anode feed gas stream has an oxygen content lower than 10%. Similarly, a 10% O, 90% CO anode product gas stream is considered O-rich by this definition, even though the oxygen content in the gas is lower than that of atmospheric air.

[0016] The typical operating temperature of an SOEC is approximately 600°C to 1000°C, and high temperatures are necessary to sufficiently enhance the oxide-ion conductivity of the ceramic membrane used as the electrolyte. Commonly used electrolyte materials include stabilized zirconia, such as yttria-stabilized zirconia (YSZ), doped ceria, and doped lanthanum gallate. Commonly used oxygen electrode materials include perovskite materials such as Sr-doped LaMnO3 (LSM), Sr-doped LaFeO3 (LSF), Sr-doped LaCoO3 (LSC), Sr-doped La(Co,Fe)O3 (LSCF), Sr-doped SmCoO3, and many others. Perovskite materials are also commonly mixed with doped ceria to form composite oxygen electrodes (SOEC anodes). Dopants other than Sr, such as Ca and Ba, are also known, as are non-perovskite materials, such as the Ruddlesden-Popper phase.

[0017] Applicant's WO2013 / 131778A2 and US10,494,728B2 both disclose the production of high purity CO by electrolysis of CO2 in a solid oxide electrolysis cell or SOEC stack.

[0018] Typically, air (N2 / O2) is used as the flush gas for the anode side of an SOEC. The O2 concentration in the gas stream leaving the anode side of the solid oxide electrolysis cell depends on the flow rate of the anode-side feed gas and the operating current of the SOEC. In principle, it is possible to produce close to 100% oxygen on the anode side by using no feed gas or pure oxygen as the feed. However, this is not usually done due to the high oxygen partial pressure and high temperature, which increases the risk of degradation of the various stack components. However, here the benefits gained outweigh the drawbacks.

[0019] In the process of the present invention, a stream containing CO2 with a low nitrogen content is used as the feed gas (sometimes called flash gas) on the anode side of the SOEC instead of air. The resulting product gas is oxygen-rich and suitable for use as an oxidant in many oxygen-consuming processes. In the context of the present invention, the term "oxygen-consuming process" refers to a process in which oxygen reacts with other chemical species, thereby oxidizing the latter. Examples of oxygen-consuming processes include oxy-combustion, oxy-sintering, and gasification.

[0020] More specifically, the present invention relates to a method for supplying oxygen-rich gas to an oxygen-consuming process, which is provided with at least one operating solid oxide electrolysis cell having a cathode side and an anode side, a) a cathode-side feed gas stream comprising steam or CO or a mixture thereof is supplied to the cathode side of at least one solid oxide electrolysis cell; b) electrochemically reducing at least a portion of the cathode feed gas stream in a solid oxide electrolysis cell, thereby forming a cathode product gas stream rich in hydrogen, carbon monoxide, or a mixture thereof; c) at least a portion of the cathode product gas stream is fed to a hydrogen and / or carbon monoxide consumption step; d) an anode-side feed gas stream comprising CO2 is supplied to the anode side of the solid oxide electrolysis cell; and e) oxygen is electrochemically generated at the anode side of the solid oxide electrolysis cell, thereby forming an oxygen-rich anode-side product gas stream; where: an oxygen-rich gas comprising at least a portion of the oxygen-rich anode-side product gas stream is supplied to an oxygen-consuming step; the oxygen-rich gas has a low nitrogen content, the nitrogen content being less than 10 vol.%; and the oxygen-rich gas leaving the solid oxide electrolysis cell has a temperature of 600°C to 1000°C; and - the process wherein the oxygen-consuming step is an oxygen combustion step or an oxygen calcination step. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 shows a method (1) according to the known art. [Figure 2] FIG. 2 shows a preferred embodiment of the method (2) according to the invention. [Figure 3] FIG. 3 shows a preferred embodiment of the method (3) according to the invention. [Figure 4] FIG. 4 shows a preferred embodiment of the method (4) according to the invention. [Figure 5] FIG. 5 shows another preferred embodiment of the method (5) according to the invention. [Figure 6] FIG. 6 shows another preferred embodiment of the method (6) according to the invention. [Figure 7] FIG. 7 shows a preferred embodiment of the method (7) according to the invention. [Figure 8] Figure 8 shows the temperature and stack voltage for two identical solid oxide electrolyte cell stacks (each containing 75 cells with a total active area of ​​approximately 8250 cm2) operated in electrolysis mode for 120 hours. DETAILED DESCRIPTION OF THE INVENTION

[0022] In the context of the present invention, the term "hydrogen and / or carbon monoxide consuming process" means a process in which hydrogen or carbon monoxide or both react to form other chemical species. Examples of hydrogen and / or carbon monoxide consuming processes include methanol production, ammonia production, hydrotreating, methanation, hydrogenation, carbonylation, hydroforming (oxo synthesis) and oxidative carbonylation.

[0023] The CO2-containing anode feed gas stream can contain 0-100 vol% CO2, for example: For example, it can contain 20 to 100, 40 to 100, 50 to 100, 60 to 100, 70 to 100, or 80 to 100 vol% CO2.

[0024] As used herein, oxyfuel combustion or oxyfuel combustion process refers to a process that uses essentially pure oxygen as the oxidant, and importantly, the process is carried out in the presence of low amounts of nitrogen (N). Oxyfuel combustion refers to the complete combustion of a fuel resulting in a non-reducible product gas, with no residual heat content remaining in the product gas.

[0025] Gasification refers to the sub-stoichiometric combustion of a fuel, with the product gas being reducing and with residual heat content in the product gas.

[0026] As used herein, oxygen calcination refers to an oxygen combustion process that decomposes solid carbonates into the corresponding oxides, for example, CaCO3 to CaO to produce cement.

[0027] The term "combustion" is meant to refer to a chemical species that can be oxidized to produce heat (an exothermic oxidation reaction).

[0028] According to one embodiment of the present invention, the anode side feed gas and / or the cathode side feed gas are heated before being fed to the solid oxide electrolysis cell. According to another embodiment of the present invention, the oxygen-rich gas is not heated before being fed to the oxygen-consuming step. Because the outlet temperature of the oxygen-rich gas from the solid oxide electrolysis cell is high, typically above 600°C, or even above 700°C, 800°C, or even above 900°C, heating can be omitted.

[0029] The present invention also relates to a solid oxide electrolysis cell, the anode side of which is in fluid communication with an oxygen-consuming process, the cell operating in accordance with the above method.

[0030] The method of the present invention has several advantages: First, insofar as a low-nitrogen anode-side feed gas is fed to the anode side of a solid oxide electrolysis cell, the oxygen-rich stream exiting the cell will also have a low nitrogen content, making it highly suitable for use as an oxidant in oxy-combustion or oxy-calcination.

[0031] According to an embodiment of the present invention, the nitrogen content in the oxygen-rich stream is 10 vol% or less, for example less than 5 vol%, 3 vol%, 2 vol%, 1 vol%, or 0.1 vol%. The less nitrogen the better.

[0032] If an oxygen-rich, simultaneously nitrogen-poor gas stream is used as the oxidizer instead of air, thermal and immediate NO x NO production pathway x Second, the exhaust gas from the oxygen-consuming process will have a low nitrogen (N2) content. This makes the technically challenging task of separating CO2 from N2 for purposes such as carbon capture, storage, and utilization much easier. Even if the oxygen-rich stream is nitrogen-free, if the fuel used in the oxy-combustion or oxy-sintering process contains nitrogen, the exhaust gas will contain some N2 or NO. xIt should be noted that the oxygen-rich stream may contain a large amount of nitrogen. Third, because the nitrogen content of the oxygen-rich stream is low compared to that of air, the energy requirements (i.e., fuel consumption) for heating the stream to the inlet temperature of the oxygen-consuming process are significantly lower due to the fact that the nitrogen component of the air is not heated. Fourth, using an oxygen-rich stream with a lower nitrogen content allows for higher flame temperatures to be achieved in the oxyfuel furnace or oxygen calciner. Fifth, using an SOEC to supply oxygen-rich gas eliminates the need for cryogenic ASUs for air separation. As mentioned above, ASUs are expensive both in terms of capital and operating costs. Sixth, because the operating temperature of an SOEC is approximately between 600°C and 1000°C, the oxygen-rich stream exiting the anode side of the solid oxide electrolysis cell does not require (or requires very little) preheating before entering the oxyfuel furnace or oxygen calciner, thereby making the process more efficient. Note that oxygen produced by cryogenic air separation requires significant preheating. Seventh, although preheating of the CO2-containing anode feed gas supplied to the anode side of the solid oxide fuel cell is required, the amount of heating required is less than with current approaches without an SOEC. This is because the electrochemically produced oxygen, which constitutes part of the oxygen-rich stream, can be at least partially heated using Joule heat generated by the SOEC. Eighth, electrochemically produced oxygen, often considered a low-value by-product of the electrolysis process, can be used instead of venting, thereby improving the efficiency and profitability of the electrolysis process. This is particularly advantageous when both product gases from the SOEC are used, i.e., the oxygen-rich anode product gas is used in the oxygen-consuming step and the H2- and / or CO-rich cathode product gas is used simultaneously in the hydrogen- and / or carbon monoxide-consuming step. Ninth, this method provides a simple way to control the oxygen content of the oxygen-rich stream entering the oxygen-consuming step. This is because the O2 concentration in the gas stream can be easily and quickly changed by changing the anode feed gas flow rate or the operating current of the SOEC.Tenth, if a portion of the hydrogen- and / or carbon monoxide-rich stream exiting the cathode side of the SOEC is used as fuel in an oxy-combustion or oxy-sintering process, and the oxygen-rich stream exiting the anode side of the SOEC is simultaneously used as an oxidant in the same oxy-combustion or oxy-sintering process, the process can potentially be carried out without the need for additional fuel. If renewable or other low-carbon energy sources are used to generate the electricity used to operate the SOEC, the methods of the present invention can be carried out with very low CO2 emissions.

[0033] The O2 concentration (which has the same meaning as concentration in this specification) in the oxygen-rich carbon dioxide gas is 0<[O2]≦100%. According to one embodiment, the lower limit of the oxygen concentration is 0.1 vol%. In another embodiment, the oxygen concentration is 10-60%, more preferably 20-40%. One molecule of O2 is electrochemically produced for every two molecules of CO and / or H2 produced electrochemically.

[0034] Thus, hydrogen or carbon monoxide or a mixture of hydrogen and carbon monoxide is electrochemically produced on the cathode side of at least one solid oxide electrolysis cell, and oxygen is electrochemically produced on the anode side of at least one solid oxide electrolysis cell in a 2:1 molar ratio (H2+CO):O2.

[0035] It is well known in the field of solid oxide fuel cells and electrolysis that CO2 negatively impacts Sr-containing anode materials, such as LSC, LSCF, and LSM. More specifically, such materials have been shown to decompose in the presence of CO2 to form SrCO3 and other phases. For example, V. Esposito et al., Solid State Ionics, 227 (2012) 46-56, describe the decomposition of SrCO3 and other phases in anode materials with the composition La. 0.6 Sr 0.4 CoO 3-δ’ When an LSC with La is exposed to pure CO2 at 800°C, 0.6 Sr 0.4-x O 3-δ”It was demonstrated that it decomposes into +xSrCO3 + 0.5(δ’ + δ’’)O2 + xCoO. Here, δ’ and δ’’ represent the oxygen non-stoichiometry in the perovskite, and x indicates the degree of decomposition (0 < x ≤ 0.4). The decomposition was confirmed by X-ray diffraction and thermogravimetric analysis. When the LSC film was exposed to pure CO2 at 780 °C, the oxygen flux (i.e., performance) passing through the LSC film decreased by more than four times. Esposito et al. concluded that "the use of CO2 is particularly harmful below 800 °C."

[0036] S. Darvish et al. (Journal of Power Sources, 336 (2016) 351 - 359) further studied the probability of SrCO3 formation as a function of temperature, CO2 partial pressure, O2 partial pressure, and LSCF composition using thermodynamic and electrochemical calculations. They proposed that the decomposition of LSCF under CO2-rich conditions occurs by the following reaction.

[0037] LSCF (reactant) + CO2 = LSCF (product) + SrCO3 + (Co,Fe)3O4 + Fe2O3 Here, LSCF (reactant) is the LSCF sample before CO2 exposure, LSCF (product) is the sample after CO2 exposure (which may have a different composition from LSCF (reactant) due to the formation of a new phase), (Co,Fe)3O4 is a cobalt-iron mixed oxide with a spinel structure, the Co:Fe ratio may vary, and Fe2O3 indicates corundum. S. Darvish et al. demonstrated that high CO2 partial pressure and low O2 partial pressure enhance the thermodynamic probability of SrCO3 formation. Specifically, they showed that 1) at temperatures higher than 427 °C, at all temperatures studied, SrCO3 becomes stable at low oxygen partial pressures, and 2) the higher the temperature, the greater the effect of any change in oxygen partial pressure on the stability of SrCO3. More specifically, under reduced pressure conditions (oxygen partial pressure 10 -5 atm) at 727 °C and exposed to 30 vol% CO2, La 0.6 Sr 0.4 Co 0.2 Fe 0.8We have shown that more than 50% of O3(LSCF) is thermodynamically decomposed to SrCO3. Furthermore, we have clarified that SrCO3 becomes more stable with increasing Sr concentration and / or decreasing Fe concentration in LSCF. Furthermore, (La 0.8 Sr 0.2 ) 0.98 Stability of MnO3 (LSM) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 The stability of O3 (LSCF) was compared and it was concluded that LSM is more stable in carbon dioxide-rich gas than LSCF.

[0038] Surprisingly, we found that under certain conditions, the problem of perovskite decomposition in CO2-rich gases is less severe than expected. More specifically, when pure CO2 is supplied to the anode side of an operating electrolysis cell or stack (where the CO2 partial pressure is close to 1 and the oxygen partial pressure is about 10), the perovskite decomposition problem in CO2-rich gases is less severe than expected. -5 We observed that, under conditions of atmospheric pressure, little or no degradation of LSCF-based electrodes was observed at typical SOEC operating temperatures. Although the formation of SrCO3 is strongly thermodynamically favored in such gas compositions, the driving force for SrCO3 formation is significantly reduced by the constant flow of oxygen ions supplied to the anode through the electrolyte. As a result, SOEC anodes can be operated in feed gases containing CO2 without significant degradation of the SOEC's performance.

[0039] With regard to the prior art, oxyfuel calciners are attracting wider interest due to their potential use in, for example, direct air capture plants, including calcium loops. For example, as already mentioned, David W. Keith et al. describe a process for capturing CO2 from the atmosphere (Joule 2, 1573-1594 (2018)).

[0040] As noted by David W. Keith et al., oxygen for oxy-fuel calciners is typically obtained by cryogenic air separation. However, as noted above, ASUs are very expensive (in terms of CAPEX as well as OPEX), and therefore it would be highly advantageous if oxygen could be supplied with lower energy demands while simultaneously reducing the nitrogen content in the gas mixture.

[0041] US9975100 suggests the importance of using a substantially nitrogen-free, oxygen-rich gas stream for the calcination of CaCO3 crystal aggregates. Such a gas stream can be obtained by low-temperature ASUs, which are expensive, especially for small-scale applications. US9975100 thereby confirms the need to avoid the presence of nitrogen in the oxidant stream supplied to an oxy-fuel calciner.

[0042] WO 2008 / 039783 discloses another calcium looping process for producing high purity hydrogen, which includes the following steps: (a) gasifying fuel to produce a raw synthesis gas containing CO, hydrogen, and steam, as well as sulfur and halide contaminants in the form of H2S, COS, and HX (where X is a halogen); (b) passing the raw synthesis gas through a water-gas shift reactor (WGSR) into which CaO and steam are injected to react with the shifted gas to remove CO2, sulfur, and X in a solid-phase calcium-containing product containing CaC03, CaS, and CaX2; (c) separating the solid-phase calcium-containing product from the rich-gas hydrogen product; and (d) regenerating CaO by calcining the solid-phase calcium-containing product in the presence of steam, CO2, synthesis gas, H2 and O2, under partial vacuum, and combinations thereof. The CaO is at least 12.0 m 2 / g and a surface area of ​​at least 0.015 cm 3 / g pore volume, and the CaO has a sorption capacity of at least about 70 g of CO2 per kg of CaO.

[0043] US2010 / 0239924 describes a fuel cell system with partial recycling of the anode exhaust. This document only refers to solid oxide fuel cell systems and partial recycling systems, and does not address the production of O2 in streams containing CO2 on the oxygen side. Furthermore, the anode of a solid oxide fuel cell refers to the fuel electrode, i.e., the electrode that typically contains metallic Ni.

[0044] US9637393 suggests a calcium loop system that includes a calciner, which reacts CaCO3 crystal aggregates to reform the calcium oxide used in the first stage of the process, releasing a gas stream containing CO2 via the reaction CaCO3(s) → CaO(s) + CO2(g).

[0045] This reaction, which takes place at approximately 900 °C and requires thermal energy as an input, is carried out in a unit commonly called a calciner. Heat can be supplied to the calciner by the combustion of hydrocarbons such as natural gas, heavy oil, coal, or biomass, or by solar heat, electricity, or a combination thereof. The calciner used can be a rotary furnace, shaft furnace, flash calciner, or fluidized bed calciner. The required heat is provided when fuel is combusted with a gas stream consisting of air or oxygen from an ASU.

[0046] The applicant's US9284651 discloses a unit for electrolyzing CO2 in a solid oxide electrolysis cell stack followed by the production of high purity CO using a gas separation unit.

[0047] WO 2014 / 154253, also owned by the same applicant, teaches the possibility of using different flush gases on the anode side. Specifically, it discloses a process for producing CO from CO in an SOEC stack. CO is directed to the fuel side of the stack with an applied current, and excess oxygen is transported to the oxygen side of the stack, optionally using air or nitrogen to flush the oxygen side. The product stream from the SOEC stack, which contains CO mixed with CO, is subjected to separation.

[0048] The above-mentioned documents belonging to the present applicant indicate that it is possible to use CO2 on the oxygen side of an SOEC. However, the reason for using CO2 on the anode side rather than air in these documents is to avoid N2 leakage to the fuel (cathode) side of the cell through small defects and pinholes that inevitably exist in the SOEC electrolyte. N2 leakage is undesirable when the purpose of the SOEC is to produce high-purity CO2 on the product side, because removing N2 from the CO gas once present is difficult and costly. In the present invention, a CO2-containing gas is intentionally used as the anode-side feed gas to obtain a CO2 / O2 mixture for downstream use in oxygen-consuming processes such as the oxygen sintering process.

[0049] An SOEC or SOEC stack can produce H from H2O and / or CO from CO2 on the cathode side. This means that any process requiring H2 and / or CO can use an SOEC for these purposes. Furthermore, the present invention makes it easier to utilize oxygen produced on the anode side of the SOEC. This, in turn, means that the SOEC can be better integrated into various processes or systems where H2 and / or CO and O2 / CO2 mixtures are required. Examples of such various processes include biomass gasification and oxyfuel (non-fossil fuel) processes. With the help of this invention, various upstream emitters of CO2, such as cement plants and steel plants, can recycle CO2 to obtain CO and O2 / CO2 mixtures. Importantly, for example, a slipstream from CO2-rich gas from an oxy-fuel-fired gasifier can be used as the anode-side feed stream for the SOEC.

[0050] According to one aspect of the present invention, there is provided a plant including a solid oxide electrolysis cell (17) having an anode side (17A) and a cathode side (17C), wherein the anode side (17A) of the cell is in fluid communication with an oxygen-consuming unit (10, 20) selected from an oxy-combustion unit or an oxy-calcination unit, and the cathode side of the cell is in fluid communication with a hydrogen and / or carbon monoxide-consuming unit (18), the plant being configured to operate a method according to any of the preceding claims. The oxy-combustion unit is a unit including associated hardware for carrying out an oxy-combustion process, such as the oxy-combustion process described above. The oxy-calcination unit is a unit including associated hardware for carrying out an oxy-combustion process, such as the oxy-calcination process described above.

[0051] As used herein, "in fluid communication" means that a free fluid passage is ensured both in operation and in operation, unless an active actuation to close the connection is or is not performed. There may be control means configured to control or split the flow of gas streams to the oxygen consuming unit and / or the hydrogen and / or carbon monoxide consuming unit.

[0052] According to an embodiment of the present invention, the oxygen consuming unit of the plant may be an oxygen calcination unit, and the hydrogen and / or carbon monoxide consuming unit may be one and the same oxygen calcination unit.

[0053] According to an embodiment of the present invention, the plant comprises control means configured to control the flow from the anode side of the solid oxide electrolysis cell to the oxygen consuming unit, such control means including valves or other hardware for reducing or splitting the gas flow.

[0054] According to an embodiment of the present invention, the plant comprises control means configured to control the flow of hydrogen and / or carbon monoxide from the cathode side of the solid oxide electrolysis cell to a consumer unit, such control means including valves or other hardware for reducing or splitting the gas stream. The present invention also includes the following items. [Item 1] A method for supplying oxygen-rich gas (206, 312, 703) to an oxygen-consuming process (10, 20), comprising providing at least one operating solid oxide electrolysis cell having a cathode side and an anode side; a) Steam or CO 2 or a mixture thereof is supplied to the cathode side (17C) of at least one solid oxide electrolysis cell (17); b) electrochemically reducing at least a portion of the cathode feed gas stream (202, 303) in a solid oxide electrolysis cell, thereby forming a cathode product gas stream (203, 304) rich in hydrogen, carbon monoxide, or a mixture thereof; c) at least a portion of the cathode product gas stream (203, 304) is fed to a hydrogen and / or carbon monoxide consuming step (18); d) CO 2 an anode side feed gas stream (205, 309) comprising: e) electrochemically generating oxygen on the anode side of the solid oxide electrolysis cell, thereby forming an oxygen-rich anode side product gas stream (206, 310), wherein: an oxygen-rich gas comprising at least a portion of the oxygen-rich anode product gas stream (206) is fed to an oxygen-consuming step; the oxygen-rich gas has a low nitrogen content, the nitrogen content being less than 10 vol.%; and the oxygen-rich gas exiting the solid oxide electrolysis cell has a temperature in the range of 600°C to 1000°C; and The method, wherein the oxygen-consuming step is an oxygen combustion step or an oxygen calcination step. [Item 2] Item 2. The method according to item 1, wherein the temperature of the oxygen-rich gas leaving the at least one solid oxide electrolysis cell is 600°C to 900°C, preferably 700°C to 850°C. [Item 3] Hydrogen or carbon monoxide or a mixture of hydrogen and carbon monoxide is electrochemically produced on the cathode side of at least one solid oxide electrolysis cell, and oxygen electrochemically produced on the anode side of at least one solid oxide electrolysis cell is converted into (H 2 +CO):O 2 The method according to item 1 or 2, wherein the molar ratio of [Item 4] 4. The method according to any one of items 1 to 3, wherein the oxygen-consuming step is oxycombustion. [Item 5] The oxygen-rich anode product gas (206, 310) is 2 5. The method according to item 4, wherein the oxygen content is ≦100%, preferably 10% to 60%, more preferably 20% to 40%. [Item 6] 5. The method according to any one of items 1 to 4, wherein the oxygen-consuming step is an oxygen-calcining step. [Item 7] The oxygen-rich anode product gas (206, 310) is 2 ]≦100%, preferably 80% to 100%, more preferably 95% to 100%. [Item 8] 8. The method according to any one of items 1 to 7, wherein at least a portion of the anode side product gas (206, 310) is recycled and used as at least a portion of the anode side feed gas (205, 309). [Item 9] 9. The method according to any one of items 1 to 8, wherein at least a portion of the cathode side product gas (203, 304) is recycled and used as at least a portion of the cathode side feed stream (202, 303). [Item 10] 10. The method according to any one of items 1 to 9, wherein a carbon dioxide-containing exhaust gas stream (112, 407, 503, 702) is obtained from the oxyfuel combustion or oxysintering process and is recycled and used as at least a portion of the cathode feed stream (202, 303) and / or anode feed gas (205, 309) supplied to the solid oxide electrolysis cell. [Item 11] 11. The method according to any one of items 1 to 10, wherein the hydrogen and / or carbon monoxide consuming step (18) comprises a methanol production step, an ammonia production step, a hydrotreating step, a methanation step, a hydrogenation step, a carbonylation step, a hydroforming (oxo synthesis) step, or an oxidative carbonylation step. [Item 12] The cathode feed streams (201, 301, 506) are CO 2 and CO in the cathode feed gas stream (201, 301, 506) and / or the anode feed gas stream (204, 307, 507). 2 The method according to any one of items 1 to 11, wherein at least a portion of is derived from one or more of the following: Metallurgical processes, cement manufacturing, carbon capture processes, direct air capture processes, and carbon-based fuel combustion processes, including the combustion of non-fossil fuels, or processes that produce CO in one or more streams 2 Other processes in which [Item 13] 13. The method according to any one of items 1 to 12, wherein the nitrogen content in the oxygen-rich stream (206,312,703) is less than 1%. [Item 14] 14. The method according to any one of items 1 to 13, wherein the nitrogen content in the oxygen-rich stream (206,312,703) is less than 0.1%. [Item 15] 15. The method of any one of items 1 to 14, wherein the solid oxide electrolysis cell is operated at or within ±0.2 V / cell of the thermoneutral voltage. [Item 16] 16. A plant comprising a solid oxide electrolysis cell (17) having an anode side (17A) and a cathode side (17C), wherein the anode side (17A) of the cell is in fluid communication with an oxygen consuming unit selected from an oxy-combustion unit or an oxy-calcination unit (10, 20) and the cathode side of the cell is in fluid communication with a hydrogen and / or carbon monoxide consuming unit (18), characterized in that the plant is configured to operate the method according to any one of items 1 to 15. [Item 17] 17. A plant according to item 16, wherein the oxygen consuming unit is an oxygen calcination unit and the hydrogen and / or carbon monoxide consuming unit is one and the same oxygen calcination unit. [Item 18] 18. A plant according to item 16 or 17, comprising control means configured to control the flow from the anode side of the solid oxide electrolysis cell to the oxygen consuming unit. [Item 19] 19. A plant according to any one of items 16 to 18, comprising control means configured to control the flow of hydrogen and / or carbon monoxide from the cathode side of the solid oxide electrolysis cell to a consumption unit.

[0055] The present invention will be explained in more detail in the following examples. [Example]

[0056] Example 1 (Comparative Example) 1, a method (1) according to the current known art is presented in which an oxygen-rich gas (104) is fed to an oxygen sinter (10), the oxygen-rich gas (104) originating from a cryogenic air separation unit (11). More specifically, an air stream (101) is fed to the cryogenic air separation unit (11), whereby the air stream (101) is separated into an oxygen-rich gas stream (102) and an oxygen-depleted gas stream (103). The gas stream (102) is preheated (e.g., to about 650°C) using a preheater (12), and the preheated stream (104) is then fed to the oxygen sinter (10). Simultaneously, a fuel stream (105) is fed to the oxygen sinter (10), which stream is optionally preheated (not shown). A solid material stream (106) containing calcium carbonate is preheated (e.g., to about 650°C) using a second preheater (13), and the preheated solid material stream (107) is fed to an oxygen calciner (10). The fuel (105) reacts with oxygen in an oxygen-rich gas stream (104), causing an exothermic combustion reaction that raises the temperature in the oxygen calciner (10) to around 900°C, thereby decomposing the calcium carbonate in the solid material (107) into calcium oxide and carbon dioxide within the oxygen calciner (10). A suitable oxygen calciner design for this purpose is a circulating fluidized bed (CFB) calciner. An output stream (108) from the oxygen calciner containing calcium oxide, carbon dioxide, and steam is fed to a first separator (14), such as a cyclone, where the stream is separated into a calcium oxide-containing stream (109) and a carbon dioxide and steam-containing stream (110). Stream (110) is further fed to a second separator (15), such as a water knock-out vessel, where stream (110) is separated into a stream (111) containing HO and a stream (112) containing carbon dioxide.

[0057] An oxygen calciner with a capacity to calcinate 300 tons of calcium carbonate per hour requires approximately 13 tons of methane or natural gas per hour as fuel and approximately 60 tons of oxygen-rich gas per hour as oxidant, assuming an oxygen content of approximately 95% in the oxygen-rich streams (102, 104). The primary impurity in the oxygen-rich streams (102, 104) originating from the air separation unit (11) is nitrogen. The higher the required oxygen content in the oxygen-rich stream (102), the lower the efficiency of the air separation unit (11). Output streams from a 300 ton / hour oxygen calciner could be, for example, a stream (109) containing calcium oxide with a flow rate of 165 tons / hour, a stream (111) containing HO with a flow rate of 30 tons / hour, and a stream (112) containing carbon dioxide with a flow rate of approximately 170 tons / hour. The carbon dioxide-containing stream (112) may have a composition of, for example, 97% CO, 1% O, 1.5% N, and 0.01% HO. While the preheater (12, 13) and separator units (14, 15) are shown as separate units in Figure 1, the preheating and separation may be performed in a unit that combines the functions of preheater and separator, such as a solid-gas cyclone. For example, the preheating of the oxygen-rich stream (102) may be performed in a cyclone in the presence of calcium oxide product from the oxygen calciner.

[0058] Example 2 2, a preferred embodiment of the method (2) according to the present invention is presented, in which an oxygen-rich gas (206) is supplied to the oxygen calciner (10), the oxygen-rich gas (206) being obtained by flushing the anode (oxy) side (17A) of at least one operating solid oxide electrolysis cell (17) with a CO2-containing feed gas (205), and at least a portion of a first cathode product gas (203) containing carbon monoxide and / or hydrogen is supplied to a hydrogen and / or carbon monoxide consumption step (18). More specifically, a first cathode feed stream (201) containing water, steam, CO2, or mixtures thereof is preheated using a cathode preheater (16), and the preheated first cathode feed stream (202) is then supplied to the cathode side (17C) of at least one solid oxide electrolysis cell (17).

[0059] Simultaneously, a first anode feed gas containing carbon dioxide (204) is preheated using an anode preheater (19), and the preheated first anode feed gas (205) is supplied to the anode (oxy) side (17A) of the solid oxide electrolysis cell. An external voltage is applied to the solid oxide electrolysis cell (17), thereby providing a driving force for electrochemically reducing at least a portion of the carbon dioxide and / or steam in the first cathode feed stream (202) to carbon monoxide and / or hydrogen, thereby forming a first cathode product gas (203) rich in hydrogen, carbon monoxide, or a mixture thereof. Some (not shown) or all of the first cathode product gas (203) is supplied to a hydrogen- and / or carbon monoxide-consuming process (18), such as a methanol production process, ammonia production process, hydrotreating process, methanation process, hydrogenation process, carbonylation process, hydroforming (oxo synthesis) process, or oxidative carbonylation process. An externally applied voltage causes an electrochemical oxidation reaction on the anode side (17A) of the solid oxide electrolysis cell, producing oxygen ions (O 2- ) is converted to molecular oxygen (O2). The electrochemically produced O2 is mixed with the preheated carbon dioxide-containing first anode feed gas (205), thereby forming a nitrogen-poor first anode product gas, oxygen-rich gas (206). The operating temperature of the solid oxide electrolysis cell (17) is typically 600-1000°C, preferably 600-900°C, or 700-850°C. Due to the high operating temperature of the solid oxide electrolysis cell, the oxygen-rich stream (206) does not need to be further heated before being fed to the oxygen calciner (10), but may be passed through a heat exchanger (not shown). Additionally, it is understood that the other aforementioned streams may be passed through a heat exchanger for better heat integration.

[0060] Simultaneously, a fuel stream (105) is fed to an oxygen calciner (10), which stream is optionally preheated (not shown). A solid material stream (106) containing calcium carbonate is preheated (e.g., to about 650°C) using a preheater (13), such as a solid-gas cyclone, and the preheated solid material stream (107) is fed to the oxygen calciner (10). The fuel (105) reacts with oxygen in the oxygen-rich stream (206), causing an exothermic combustion reaction that raises the temperature in the oxygen calciner (10) to about 900°C, where the calcium carbonate in the solid material (107) is decomposed into calcium oxide and carbon dioxide. An output stream (108) from the oxygen calciner containing calcium oxide, carbon dioxide, and steam is fed to a first separator (14), such as a cyclone, where the stream is separated into a calcium oxide-containing stream (109) and a carbon dioxide and steam-containing stream (110). Stream (110) is further fed to another separator (15), such as a water knock-out vessel, where the stream is separated into a stream (111) containing H2O and a stream (112) containing carbon dioxide.

[0061] An oxygen calciner with a capacity to calcinate 300 tons of calcium carbonate per hour requires approximately 13 tons of methane or natural gas per hour as fuel and approximately 61 tons of oxygen-rich gas per hour as oxidant, assuming an oxygen content of 95 vol% in the oxygen-rich stream (206) with the balance CO2. The required flow rate of the first anode feed stream (204) depends on the desired oxygen content in the oxygen-rich stream (206). To supply the oxygen calciner with an oxygen-rich gas (206) containing 95 vol% O2 in 61 tons of CO2, approximately 4 tons of CO2 must be supplied to the anode side (17A) of the electrolysis unit (17). The amount of oxygen produced in the solid oxide electrolysis cell (17) is determined by Faraday's law. To produce 57 tons of oxygen per hour, the electrolysis cell requires a current of approximately 191,000,000 A. A typical electrolysis current for a solid oxide electrolysis cell is 0.5 A / cm2. 2 ~1A / cm 2 Therefore, the required electrode area of ​​the electrolysis unit (17) under the above conditions is 19,100 m 2 ~38,200m2 Such an electrolysis unit would produce about 7 tons of hydrogen per hour at the cathode side of the cell when pure water or steam is used as the first cathode feed stream (201) to the cell, or about 100 tons of CO per hour at the cathode side of the cell when pure CO is used as the first cathode feed stream (201) to the cell. The highest system efficiency is achieved when the electrolysis unit (17) is operated near thermoneutral voltage.

[0062] The nitrogen content of the oxygen-rich gas stream (206) is determined by the nitrogen content in the first anode feed gas stream (204). For example, if the first anode feed gas stream (204) has a nitrogen content of 1 vol.% and the desired oxygen content in the oxygen-rich gas stream (206) is 95 vol.%, the resulting nitrogen content in the oxygen-rich gas stream (206) is approximately 0.05 vol.%.

[0063] Example 3 3, a preferred embodiment of the method (3) according to the present invention is presented, in which an oxygen-rich gas (312) is supplied to an oxygen calciner (10), the oxygen-rich gas (312) being obtained by flushing the anode (oxy) side (17A) of at least one solid oxide electrolysis cell (17) with a CO2-containing anode feed gas (308, 309), wherein at least a portion of a carbon monoxide- and / or hydrogen-rich first cathode product gas (304, 305) is supplied to a hydrogen and / or carbon monoxide consumption step (18), and a portion of either or both of the product gas streams (304, 310) from the solid oxide electrolysis cell (17) is recycled back to the cell. More specifically, a first cathode feed stream (301) containing water, steam, CO2, or a mixture thereof is preheated using a cathode preheater (16). The preheated first cathode feed stream (302) is optionally mixed with a first cathode recycle stream (306) to provide a second cathode feed stream (303), which is fed to the cathode side (17C) of at least one solid oxide electrolysis cell (17). An external voltage is applied to the solid oxide electrolysis cell (17), thereby providing a driving force for electrochemically reducing at least a portion of the carbon dioxide and / or steam in the second cathode feed stream (303) to carbon monoxide and / or hydrogen, thereby forming a first cathode product gas (304) rich in hydrogen, carbon monoxide, or a mixture thereof. Optionally, a portion of the first cathode product gas (304) is recycled back to the electrochemical cell (17) as the first cathode recycle stream (306). The remainder of the first cathode product gas (305) is fed to the hydrogen and / or carbon monoxide consumption step (18). Although not specifically shown in Figure 3, the division of the first cathode product gas (304) into streams (305) and (306) may be performed in a separation unit such as a pressure swing adsorber or temperature swing adsorber or membrane separator. An additional blower or compressor may be included to increase the pressure of stream (304).

[0064] Simultaneously, a first anode side feed stream containing carbon dioxide (307) is preheated using an anode side preheater (19). The preheated first anode side feed stream (308) is optionally mixed with a first anode side recycle stream (311) to obtain a second anode side feed stream (309), which is fed to the anode side (17C) of at least one solid oxide electrolysis cell (17). An externally applied voltage drives an electrochemical oxidation reaction in the anode side (17A) of the solid oxide electrolysis cell, thereby producing oxygen ions (O 2- ) is converted to molecular oxygen (O2). The electrochemically produced O2 is mixed with the second anode side feed gas containing carbon dioxide (309), thereby forming a nitrogen-depleted first anode side product gas (310). Optionally, a portion of the oxygen-rich first anode side product gas (310) is recycled back to the electrochemical cell (17) as a first anode side recycle stream (311). The remaining oxygen-rich first anode side product gas (312) is fed to the oxygen sinter (10) with CO2 recycled from the exhaust gas to the SOEC, resulting in an oxygen sinter + SOEC. Although not specifically shown in FIG. 3 , the splitting of the first anode side product gas (310) into streams (311) and (312) can be accomplished in a separation unit such as a pressure swing adsorber, a temperature swing adsorber, or a membrane separator. An additional blower or compressor may be included to increase the pressure of stream (310). Due to the high operating temperature of the solid oxide electrolysis cell, the oxygen-rich stream (312) does not need to be further heated, but may be passed through a heat exchanger (not shown). It is further understood that the other aforementioned streams may be passed through a heat exchanger or additional preheaters for better heat integration.

[0065] Example 4 4, a preferred embodiment of the method (4) according to the invention is presented, in which an oxygen-rich gas (312) is fed to an oxy-fuel combustion chamber (20), the oxygen-rich gas (312) being obtained by flushing the anode (oxygen) side (17A) of at least one solid oxide electrolysis cell (17) with a CO2-containing anode feed gas (308, 309), and wherein at least a portion of the carbon monoxide- and / or hydrogen-rich first cathode product gas (304, 305) is fed to a hydrogen and / or carbon monoxide consumption step (18), and a portion of either or both output gas streams from the solid oxide electrolysis cell (17) is recycled back to the cell as described in Example 3. Advantageously, the oxygen content in the first anode product gas (310, 312) is between 20% and 40% by volume, e.g., 35% by volume, to match the heat capacity of air and obtain flame temperatures similar to those in an air-blown furnace. It is understood that the aforementioned streams may be passed through a heat exchanger or additional preheater for better thermal integration. Suitable oxy-fuel combustion chamber designs for this purpose include pulverized fuel furnaces or circulating fluidized bed (CFB) furnaces. At the same time, a solid fuel stream (401), e.g., coal, wood, or biomass, is optionally preheated using a preheater (21), thereby obtaining a preheated solid fuel stream (402). The preheated solid fuel stream (402) is fed into the oxy-fuel combustion chamber (20). In the combustion chamber (20), the solid fuel (402) reacts with oxygen in the oxygen-rich gas stream (312), resulting in an exothermic combustion reaction that raises the flame temperature near the burner (1-4 m from the burner) to above 1100°C, even up to 1900°C.

[0066] The output stream (403) from the oxy-combustion chamber (20), which contains solid combustion residues, carbon dioxide, and steam, is fed to a first separator (22), such as a cyclone, which separates the stream into a stream (404) containing solid combustion residues and a stream (405) containing carbon dioxide and steam. Stream (405) is further fed to a second separator (23), such as a water knock-out vessel, which separates the stream into a stream (406) containing HO and a stream (407) containing carbon dioxide. Additional separation steps may be required and are known to those skilled in the art.

[0067] For a 0.21 MW pilot-scale coal oxy-combustion unit, 31 kg per hour of solid fuel (coal) stream (401) and 233 kg per hour of oxygen-rich stream (312) are required, assuming an oxygen content of 35 vol%, balance CO2, and 5% excess oxygen in the oxygen-rich stream (312). The output stream (403) from the oxy-combustion chamber (20) has significantly lower nitrogen oxide (NO) emissions compared to an air-blown furnace. x ) contains less NO x The concentration is a function of flame temperature, thereby increasing when a high oxygen content oxygen-rich stream (312) is used. The nitrogen content in the solid fuel streams (401, 402) also increases with the NO in stream (403). x Affects concentration.

[0068] Example 5 In FIG. 5, another preferred embodiment of the method (5) according to the present invention is presented, in which an oxygen-rich gas (206) is fed to an oxygen calciner (10), the oxygen-rich gas (206) being obtained by flushing the anode (oxygen) side (17A) of at least one solid oxide electrolysis cell (17) with a first anode side feed gas (205) comprising CO, wherein at least a portion of the carbon monoxide and / or hydrogen-containing gas (203) is fed to a hydrogen and / or carbon monoxide consumption step (18), and an exhaust gas stream comprising carbon dioxide (503) is recycled, i.e., at least a portion of one or both of the feed gas streams (201, 204) to the electrolysis unit comprises at least a portion of the exhaust gas stream comprising carbon dioxide (503). Specifically, a carbon dioxide-containing exhaust gas stream (501) is split into two equal or unequal portions, where a first portion (502) of the carbon dioxide-containing stream is directed out of the process, while a second portion (503) of the carbon dioxide-containing stream is used to provide the electrolysis stack feed gas. More specifically, stream (503) is split into two equal or unequal portions (504, 505), where stream (504) is optionally mixed with an auxiliary cathode feed stream (506) containing water, steam, CO2, or a mixture thereof, thereby obtaining the first cathode feed stream (201). Stream (505) is optionally mixed with an auxiliary anode feed stream (507) containing CO2, thereby obtaining the first anode feed gas (204). In one embodiment of the method according to the present invention, the auxiliary gas stream (506) contains steam and has a low CO2 content. It is understood that the carbon dioxide containing stream (503) may be fed to either or both of the solid oxide electrolysis cells (17).

[0069] Example 6 6, another preferred embodiment of the method (6) according to the present invention is presented, in which an oxygen-rich gas (206) is supplied to an oxygen calciner (10), the oxygen-rich gas (206) being obtained by flushing the anode (oxy) side (17A) of at least one solid oxide electrolysis cell (17) with a CO2-containing feed gas (205), and at least a portion of a first cathode product gas (203) containing carbon monoxide and / or hydrogen is supplied to a hydrogen and / or carbon monoxide consumption step (18), while a portion of the first cathode product gas (203) containing carbon monoxide and / or hydrogen is supplied as a fuel stream (602) to the oxygen calciner (10). More specifically, the first cathode product gas (203) is split into two equal or unequal portions (601, 602). Stream (601) is fed to a hydrogen and / or carbon monoxide consuming step (18), while stream (602) is used as fuel in an oxygen calciner (10). The hydrogen and / or carbon monoxide rich stream (602) can be mixed with additional fuel (603), such as methane, natural gas, hydrogen, or carbon monoxide, to obtain a combined fuel stream (604) that is fed to the oxygen calciner (10). It is understood that, as described in Examples 3 and 4 and not explicitly shown in FIG. 6, portions of streams (203, 206) can be recycled to the corresponding sides of the solid oxide electrolysis cell.

[0070] Example 7 7, a preferred embodiment of the method (7) according to the invention is presented, in which an oxygen-rich gas (703) is fed to an oxy-fuel combustion chamber (20), the oxygen-rich gas (703) being obtained by mixing (in equal or unequal amounts) the following gas streams: an oxygen-rich first anode side product gas (312) obtained by flushing the anode (oxygen) side (17A) of at least one solid oxide electrolysis cell (17) with a CO2-containing anode side feed gas (308, 309), and an exhaust gas stream (701) obtained by splitting a CO2-containing exhaust gas stream (407) into two equal or unequal portions (701, 702). Stream (702) is directed out of the system, while stream (701) is recycled as explained above. Advantageously, the oxygen content in the first anode side product gas (310, 312) is between 90 vol% and 100 vol%, for example 95 vol%, to minimize the total gas flow through the anode compartment of the solid oxide electrolysis cell. Advantageously, the oxygen content in the oxygen-rich gas (703) is between 20 vol% and 40 vol%, for example 35 vol%, to match the heat capacity of air and obtain flame temperatures similar to those in an air-blown furnace.

[0071] Example 8 Two identical solid oxide electrolyte cell stacks (each containing 75 cells, with a total active area of ​​approximately 8250 cm) 2The stack was operated in electrolysis mode for 120 hours (Figure 8). The first cathode feed stream (301), containing ≥99·9% (≥99.9%) CO2, was mixed with the first cathode recycle stream (306), containing CO and CO2, to obtain the second cathode feed stream (303). The second cathode feed stream (303) was simultaneously introduced into the cathode compartments of both stacks at a temperature of 800 °C (Figure 8a). An electrolysis current was applied to both stacks, resulting in the electrochemical conversion of a portion of the CO2 in the cathode feed stream to CO, thereby enriching the first cathode product stream (304) exiting the stacks with CO. The temperature of the stream (304) exiting the stacks was 751–753 °C. This gas was compressed and fed to a pressure swing adsorber unit. The CO2-rich outlet stream (305) from the pressure swing adsorber unit was recovered as a product for use in, for example, a phosgene plant, and the CO2-lean outlet stream (306) from the pressure swing adsorber unit was mixed with the first cathode feed stream (301) as described above. The first anode feed stream (204), containing ≥99.9% (99.9% or greater) CO2, was preheated to 785°C, and the resulting preheated first anode feed stream (205) was fed to the anode side of both stacks. An electrolysis current was passed through the stacks, resulting in electrochemical production of gaseous O2 in the anode side of the cells within the stacks, thereby producing an oxygen-rich first anode product gas (206). The first anode product gas (206) contained CO2 and O2 and had a significantly lower nitrogen content. The exact nitrogen content was not measured but was estimated to be less than 50 ppm. The temperature of the first anode-side product gas (206) exiting the stack ranged from 791 to 793 °C during the experiment. The stack voltage required to maintain an electrolysis current of approximately 45 A ranged from 97 V to 103 V (Figure 8b). Surprisingly, no significant performance degradation was observed when operating the solid oxide electrolysis cell using an anode-side stream containing ≥99.9% (99.9% or greater) CO2.

Claims

1. A method for supplying oxygen-rich gas (206, 312) to an oxygen-consuming process (10), which is an oxygen-calcination process, comprising providing at least one operating solid oxide electrolysis cell having a cathode side and an anode side; a) Steam or CO ２ or a mixture thereof is supplied to the cathode side (17C) of at least one solid oxide electrolysis cell (17); b) electrochemically reducing at least a portion of the cathode feed gas stream (202, 303) in a solid oxide electrolysis cell, thereby forming a cathode product gas stream (203, 304) rich in hydrogen, carbon monoxide, or a mixture thereof; c) at least a portion of the cathode product gas stream (203, 304) is fed to a hydrogen and / or carbon monoxide consumption step (18); d) CO ２ an anode side feed gas stream (205, 309) comprising: e) electrochemically producing oxygen on the anode side of the solid oxide electrolysis cell, thereby forming an oxygen-rich anode-side product gas stream (206, 310), wherein: an oxygen-rich gas comprising at least a portion of the oxygen-rich anode product gas stream (206) is fed to an oxygen-consuming step; the oxygen-rich gas has a low nitrogen content, the nitrogen content being less than 10 vol.%; and The process described above, wherein the oxygen-rich gas leaving the solid oxide electrolysis cell has a temperature in the range of 600°C to 1000°C.

2. 2. The method according to claim 1, wherein the temperature of the oxygen-rich gas leaving the at least one solid oxide electrolysis cell is between 600°C and 900°C, preferably between 700°C and 850°C.

3. Hydrogen or carbon monoxide or a mixture of hydrogen and carbon monoxide is electrochemically produced on the cathode side of at least one solid oxide electrolysis cell, and oxygen electrochemically produced on the anode side of at least one solid oxide electrolysis cell is converted into (H ２ +CO): O ２ 3. The method of claim 1 or 2, wherein the molar ratio of

4. The oxygen-rich anode side product gas (206, 310) is 0<[O ２ 4. The method according to claim 1, wherein the oxygen content is ≦100%, preferably between 80% and 100%, more preferably between 95% and 100%.

5. The method according to any one of claims 1 to 4, wherein at least a portion of the anode side product gas (206, 310) is recycled and used as at least a portion of the anode side feed gas (205, 309).

6. The method according to any one of claims 1 to 5, wherein at least a portion of the cathode side product gas (203, 304) is recycled and used as at least a portion of the cathode side feed stream (202, 303).

7. 7. The method of any one of claims 1 to 6, wherein a carbon dioxide-containing exhaust gas stream (112, 407, 503) is obtained from the oxygen calcination step and is recycled and used as at least part of the cathode side feed stream (202, 303) and / or the anode side feed gas (205, 309) supplied to the solid oxide electrolysis cell.

8. 8. The method of claim 1, wherein the hydrogen and / or carbon monoxide consuming process (18) comprises a methanol production process, an ammonia production process, a hydrotreating process, a methanation process, a hydrogenation process, a carbonylation process, a hydroforming (oxo synthesis) process, or an oxidative carbonylation process.

9. The cathode feed stream (201, 301, 506) is CO ２ and CO in the cathode feed gas stream (201, 301, 506) and / or the anode feed gas stream (204, 307, 507). ２ The method of any one of claims 1 to 8, wherein at least a portion of the metallurgical processes, cement manufacturing, carbon capture processes, direct air capture processes, and carbon-based fuel combustion processes, including the combustion of non-fossil fuels, or processes that produce CO in one or more streams ２ Other processes in which

10. The method of any one of claims 1 to 9, wherein the nitrogen content in the oxygen-rich stream (206, 312) is less than 1%.

11. The method of any one of claims 1 to 10, wherein the nitrogen content in the oxygen-rich stream (206, 312) is less than 0.1%.

12. 12. The method of any one of claims 1 to 11, wherein the solid oxide electrolysis cell is operated at or within ±0.2 V / cell of the thermoneutral voltage.

13. a solid oxide electrolysis cell (17) having an anode side (17A) and a cathode side (17C); an oxygen consuming unit, which is an oxygen calcination unit (10); and Hydrogen and / or carbon monoxide consumption unit (18) wherein the anode side (17A) of the cell is in fluid communication with the oxygen consuming unit and the cathode side of the cell is in fluid communication with a hydrogen and / or carbon monoxide consuming unit (18), characterized in that the plant is configured to operate the method according to any one of claims 1 to 12.

14. 14. The plant of claim 13, comprising control means configured to control flow from the anode side of the solid oxide electrolysis cell to the oxygen consuming unit.

15. A plant according to any one of claims 13 to 14, comprising control means arranged to control the flow of hydrogen and / or carbon monoxide from the cathode side of the solid oxide electrolysis cell to a consumer unit.

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