CN116161623A - Method and device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cyclic hydrogen production - Google Patents
Method and device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cyclic hydrogen production Download PDFInfo
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Abstract
The invention discloses a method and a device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cyclic hydrogen production, and relates to the technical field of sulfur-iodine cyclic hydrogen production. The invention improves the HIx phase treatment flow of the thermochemical sulfur-iodine cycle hydrogen production process, and sends the high-temperature mixed gas decomposed by the HI decomposing tower into a membrane separator to obtain a hydrogen gas stream, a liquid water stream, HI and I 2 High temperature mixed gas streams, HI and I 2 Spraying the high-temperature mixed gas flow into an HIx phase purification concentration tower in a bubble mode, stirring the HIx phase by stirring the HIx phase under the disturbance of bubbles, and avoiding I 2 Is to increase the HI concentration in the liquid while H in the HIx phase 2 SO 4 The impurities are removed by Bunsen reverse reaction with HI. The invention couples the HIx purification section and the concentration section together, thereby greatly simplifying the whole system. The heat of the high-temperature gas generated by HI decomposition is integrated into the HIx purification concentration section, so that the energy cascade utilization of the process and the system is realized.
Description
Technical Field
The invention relates to the technical field of sulfur-iodine cyclic hydrogen production, in particular to a method and a device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cyclic hydrogen production.
Background
Hydrogen energy is a secondary energy source, also known as a high efficiency source of zero pollution, which can be produced by a variety of methods. In addition, the fuel can be directly converted into electric energy and water in the combustion process, no pollutant is discharged, and the fuel has a great advantage compared with some traditional chemical dyes. Hydrogen energy can be applied in a large scale in a variety of fields including industry, construction industry, traffic, etc., with end use applications achieving low carbonization and zero pollution goals. The water can produce hydrogen through thermal dissociation, but the reaction needs high temperature above 2500 ℃, the sulfur-iodine cycle hydrogen production method divides the decomposition reaction of water into a plurality of steps, so that the reaction temperature can be reduced, the problem of hydrogen-oxygen separation can be avoided, and sulfur dioxide and iodine used in the cycle can be recycled. The Sulfur Iodine (SI) cycle was first proposed by the us atomic energy (General atomic) company in the 1970 s. Due to the great advantages, the full-flow phase process is easy to run continuously, has high energy utilization efficiency, is completely closed, and can be matched with nuclear energy or solar energy. The sulfur-iodine cycle has the potential of large-scale and low-cost hydrogen production. Thermochemical sulfur-iodine cycle (SI cycle) consists essentially of three steps of reactions:
SO 2 + 2H 2 O +I 2 = H 2 SO 4 + 2HI （333-393K）；
2H 2 SO 4 = 2SO 2 +2H 2 O + O 2 （1123K）；
2HI = H 2 + I 2 (773K)。
the sulfur-iodine circulation system comprises three subsystems, a Bunsen reaction subsystem, H 2 SO 4 And the decomposition subsystem is HI decomposition subsystem. First, sulfur dioxide and excess iodine and excess water undergo a Bunsen reaction to produce a mixed solution of sulfuric acid and hydroiodic acid. Under the condition of excessive iodine and water, the solution can spontaneously generate liquid-liquid delamination phenomenon. The upper light phase solution is sulfuric acid phase, mainly sulfuric acid solution, and the lower heavy phase is hydroiodic acid phase(HIx), mainly HI-I 2 -H 2 The ternary mixed solution of O inevitably contains a small amount of sulfuric acid impurities due to the limitation of liquid-liquid delamination. Since the separated HIx phase solution contains impurities, and the impurities contained therein have a large influence on the subsequent processes, it is necessary to conduct purification treatment, i.e., to carry out small amounts of HI and H by the reverse reaction of Bunsen reaction 2 SO 4 Reconversion to I 2 、SO 2 、H 2 S and H 2 O. The Bunsen reaction is endothermic, so that under certain conditions (temperature>120 ℃ can initiate the following side reactions:
H 2 SO 4 +8HI＝H 2 S+4I 2 +4H 2 O；
H 2 SO 4 +2HI＝SO 2 +I 2 +2H 2 O。
in the environment with higher temperature, H 2 S and SO 2 Very low solubility in water, H 2 S and SO 2 Escape from the liquid for purification purposes. After purification of the HIx phase solution, concentration is required to increase the HI concentration to an ultra-constant boiling state. Then rectifying and separating by a conventional rectifying tower, wherein the bottom kettle liquid is I-containing 2 The HIx solution with higher concentration, while the rectification at the top of the tower is HI with high concentration, and then enters into a HI decomposition reactor to be decomposed into hydrogen and iodine simple substance at about 450 ℃. H 2 SO 4 Similar to the HIx phase operation, multiple flash stages are required to increase H 2 SO 4 Is then introduced into H 2 SO 4 Decomposition of the reactor into SO 2 、O 2 And H 2 O, thereby forming a complete closed loop. The whole system only needs to continuously supplement water and heat, and other substances can be recycled, so that high-purity hydrogen and oxygen can be obtained.
To ensure the subsequent separation of the hydriodic acid phase (HIx) and sulfuric acid phase, an excess of I is added to the system 2 . The solid iodine is purple black glossy flaky crystals, is easy to sublimate and sublimate, and is extremely easy to precipitate and deposit at the bottom of the container and block the pipeline. H 2 SO 4 And HI are decomposed to generate high-temperature mixed gas, which is required to be condensed and cooled firstAnd then returned to the Bunsen reaction tank, which causes a great deal of energy waste.
CN107904617a discloses a method and apparatus for producing hydrogen by electrochemical decomposition of HI in sulfur-iodine cycle hydrogen production, but electrochemical methods consume electric energy, contrary to the original purpose of thermochemistry; meanwhile, the corrosion resistance requirement on the electrode material is extremely high, and the manufacturing cost is high; the cell receptor volume is limited and it is difficult to realize large-scale industrial applications. CN107944217a provides a modeling method for HI concentration rectifying tower in iodine-sulfur cycle hydrogen production, solves the problem of HI concentration and separation rectifying in iodine-sulfur cycle hydrogen production, does not mention actual process equipment, simplifies the material, and omits impurity entrainment in HIx phase. CN101830443a provides a new process for purifying sulfuric acid phase and hydroiodic acid phase in the sulfur-iodine cycle, but introduces a mixed gas of oxygen and inert gas, which is unfavorable for the later separation to obtain high purity hydrogen. CN114852960a provides a method and apparatus for separating, concentrating and purifying two phases in sulfur-iodine cyclic hydrogen production, which uses gradual pressure decrease to realize step separation of HI gas, but does not use heat of HI decomposed high-temperature gas, and does not use the heat of the HI decomposed high-temperature gas to separate the non-decomposed HI from H 2 O is separated, and repeated concentration causes energy waste; CN114195094a provides a full-flow method and apparatus for preparing hydrogen by thermochemical sulfur-iodine cycle, which is to introduce the high-temperature mixed gas generated after sulfuric acid decomposition into the downstream HIx solution to make a large amount of water in the HIx system be carried away by vaporization, so as to achieve the purpose of concentrating HI solution, but not using the heat of the high-temperature gas after HI decomposition, and at the same time, not using the undigested HI and H 2 O separates, and repeated concentration causes energy waste.
The iodine-sulfur circulation hydrogen production process has high hydrogen production efficiency and no CO 2 The emission is favorable for carbon neutralization, so that the iodine-sulfur cycle is expected to become a clean, economical and sustainable large-scale hydrogen production method. However, the equipment system of the conventional iodine-sulfur cycle is very complex and huge, and comprises a Bunsen reaction tower, a liquid-liquid separation tower, HI and H 2 SO 4 Purification column, condensation column, several HI and H 2 SO 4 Rectifying column, HI and H 2 SO 4 Decomposing tower, buffer tank and multipleA heater, etc. The presence of excess water in the system requires distillation for HI solution and H 2 SO 4 The concentration of the solution consumes a lot of energy. The existence of excessive iodine is easy to deposit at the bottom of the container to increase the recovery difficulty, and the pipeline is easy to be blocked after precipitation. From H 2 SO 4 And the high-temperature mixed gas generated in the HI decomposing tower must be cooled first to enter the Bunsen reaction tower, and the process causes energy waste.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method and a device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cycle hydrogen production.
The technical scheme of the invention is as follows:
the invention firstly provides a method for purifying and concentrating HIx phase of thermochemical sulfur-iodine cyclic hydrogen production, which comprises the following steps:
s1: the HIx phase liquid generated by the Bunsen reaction tower is added into a HIx phase purification concentration tower to form a continuous liquid phase in the tower, HI and I from a membrane separator 2 Introducing a high-temperature mixed gas flow from the bottom of the HIx phase purification concentration tower, enabling the high-temperature mixed gas to be in contact with HIx phase liquid in a bubble form, partially vaporizing water in the HIx phase liquid, stirring the liquid mixture by the disturbance of the bubbles, and avoiding I 2 Is dissolved in the HIx phase liquid to increase the concentration of HI in the liquid, and H in the HIx phase 2 SO 4 The impurity undergoes Bunsen reverse reaction with HI and is converted into H 2 S、SO 2 Returns to the Bunsen reaction tower to carry out the reaction,
s2: high concentration HI and I at the bottom of HIx phase purification concentration column 2 The mixed solution enters a microporous filter for cooling, I 2 Filtering to remove HI solution, and decomposing in HI decomposing tower;
s3: delivering the decomposed mixed gas of the HI decomposing tower into a membrane separator, and separating the decomposed mixed gas by the membrane separator to obtain three streams: hydrogen gas stream, liquid water stream, HI and I 2 A high temperature mixed gas stream; wherein HI and I 2 The mixed gas flow returns to the bottom of the HIx phase purification concentration tower, and the hydrogen flow leaves the membrane separator and enters the alkali washing tank to obtainTo H 2 As a product output.
The invention also provides a device for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production, which comprises:
a HIx phase purification concentration column comprising at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet; the liquid phase inlet is used for receiving HIx phase liquid obtained by Bunsen reaction at the upstream of thermochemical sulfur-iodine circulation, and the gas phase inlet is connected with the membrane separator and used for receiving HI and I obtained by separation of the membrane separator 2 A high temperature mixed gas stream; the liquid phase outlet is connected with the microporous filter for discharging high-concentration HI and I 2 The mixed solution, the said gas phase exports and links with Bunsen reaction tower and discharges the mixed gas;
microporous filter for filtering high concentration HI and I 2 I in the mixed solution 2 ；
The HI decomposing tower is connected with the microporous filter, and is used for receiving the HI solution filtered by the microporous filter and decomposing the HI solution;
the membrane separator is used for separating decomposed mixed gas of the HI decomposing tower to obtain three streams: hydrogen gas stream, liquid water stream, HI and I 2 A high temperature mixed gas stream; wherein HI and I 2 The high temperature mixed gas stream is fed to the gas phase inlet of the HIx phase purification concentration column.
Further, in a preferred embodiment, the apparatus further comprises a Bunsen reaction column, a liquid-liquid separation column, H 2 SO 4 Concentration tower, H 2 SO 4 A decomposing tower; the Bunsen reaction tower is used as a place where Bunsen reaction occurs, and the liquid-liquid separation tower is used for standing and layering a mixture after Bunsen reaction; h 2 SO 4 The concentration column is used for separating H from the liquid-liquid separation column 2 SO 4 Concentrating the phase mixture; h 2 SO 4 Decomposing tower pair channel H 2 SO 4 The sulfuric acid solution concentrated by the concentration tower is decomposed, and high-temperature mixed gas generated by decomposition enters the Bunsen reaction tower to participate in Bunsen reaction.
Compared with the prior art, the invention has the beneficial effects that:
the invention sends the decomposed mixed gas of the HI decomposing tower into the membrane separator, the membrane separator separates the decomposed mixed gas, macromolecular HI and I 2 (relative H) 2 And H 2 O) can not pass through the membrane and leave from the left side of the membrane and is pressurized by a compressor and then is introduced from the bottom of the HIx purification concentration tower; small molecule H 2 And H 2 O (relative HI and I) 2 ) After passing through the membrane, the water is condensed into liquid by a condensation plate on the right side of the membrane, and the liquid leaves the membrane separator, and hydrogen is output as a product after washing.
The invention is realized by combining HI and I 2 The mixed gas stream is pressurized and injected into the HIx phase purification concentration tower to cause agitation of liquid, thereby preventing I 2 Is deposited. Meanwhile, HI gas is very easy to dissolve in water, and high-temperature mixed gas accelerates the vaporization of water, so that the purpose of improving the concentration of HI solution is achieved. HI and impurity H under high temperature conditions 2 SO 4 Reaction to form SO 2 And H 2 S，SO 2 、H 2 S and H 2 The O mixed gas leaves the HIx phase purification concentration tower (SO at high temperature) 2 And H 2 S is at H 2 The solubility in O is extremely low), and the purpose of purifying the HIx solution is achieved.
The invention couples the HIx purification section and the concentration section together, thereby greatly simplifying the whole system. The heat of the high-temperature gas generated by HI decomposition is integrated into the HIx purification concentration section, so that the energy cascade utilization of the process and the system is realized.
Drawings
FIG. 1 is a partial flow chart of HIx phase purification and concentration according to the present invention.
FIG. 2 is a schematic diagram of the whole process flow of the sulfur-iodine cyclic hydrogen production of the invention.
FIG. 3 is a schematic diagram of a gas injection apparatus for a HIx phase purification concentration column.
In the figure: 1-Bunsen premix tank, 2-Bunsen reaction tower, 3-liquid separation tower, 4-HIx phase purification and concentration tower, 5-microporous filter, 6-HI decomposition tower, 7-H 2 SO 4 Concentration tower, 8-H 2 SO 4 A decomposing tower, a 9-NaOH washing tank; 10-a membrane separator; 11-compressor.
Detailed Description
The invention is further illustrated and described below in connection with specific embodiments. The described embodiments are merely exemplary of the present disclosure and do not limit the scope. The technical features of the embodiments of the invention can be combined correspondingly on the premise of no mutual conflict.
The invention mainly provides a method and a device for purifying and concentrating HIx phase of thermochemical sulfur-iodine cycle hydrogen production, wherein the thermochemical sulfur-iodine cycle hydrogen production has more literature reports, and the technical scheme provided by the invention belongs to a part of links in the whole flow of thermochemical sulfur-iodine cycle hydrogen production, and specifically belongs to the treatment flow of HIx phase; for other links (such as Bunsen reaction process, H) in the whole flow of thermochemical sulfur-iodine cycle hydrogen production 2 SO 4 Phase process flow, etc.), the present invention is not limited. The technical scheme of the invention can be combined into the whole flow of the existing thermochemical sulfur-iodine cycle hydrogen production to replace the HIx phase treatment flow in the existing technology. For comparison, the flow of the invention is shown in figure 1 alone, and a typical whole flow process of thermochemical sulfur-iodine cycle hydrogen production based on the technology of the invention is shown in figure 2.
As shown in FIG. 1, the apparatus for purifying and concentrating HIx phase of thermochemical sulfur-iodine cycle hydrogen production mainly comprises an HIx phase purifying and concentrating tower 4, an HI decomposing tower 6, a membrane separator 10, a microporous filter 5 and a NaOH washing tank 9. Wherein the HIx phase purification concentration column comprises at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet; the liquid phase inlet is used for receiving HIx phase liquid of the thermochemical sulfur iodine circulating upstream process, and the gas phase inlet is connected with the membrane separator 10 and is used for receiving HI and I obtained by separation through the membrane separator 2 A high temperature mixed gas stream; the liquid phase outlet is connected to a microporous filter 5 for discharging high concentrations HI and I 2 The mixed solution, the gas phase outlet is connected with the Bunsen reaction tower 2 to discharge the mixed gas.
The NaOH washing tank in the figure 1 is used for removing acid gas and water vapor in the mixed gas to obtain product hydrogen; the microporous filter 5 is used for filtering and removing I in the high-concentration HI solution 2 The method comprises the steps of carrying out a first treatment on the surface of the The HI decomposing tower 6 is connected with the microporous filter 5 and receives the microporous filterFiltering the HI solution and decomposing to obtain HI and H 2 、I 2 And H 2 O high temperature mixed gas.
Further, as shown in FIG. 3, the bottom of the HIx purification concentration column is provided with a gas distributor, HI and I 2 The high-temperature mixed gas is dispersed by a gas distributor and then enters into HIx phase liquid.
The membrane separator is used for separating decomposed mixed gas of the HI decomposing tower to obtain three streams: hydrogen gas stream, liquid water stream, HI and I 2 A high temperature mixed gas stream; wherein HI and I 2 The high temperature mixed gas stream is fed to the gas phase inlet of the HIx phase purification concentration column.
The membrane separator adopts a silicon dioxide separation membrane which is an inorganic membrane commonly used for producing hydrogen by HI decomposition and has water permeability. Macromolecular HI and I can be achieved by using a silica separation membrane 2 Unable to pass through membrane, small molecule H 2 And H 2 O can pass through the membrane, and then the water vapor after passing through the membrane is condensed into liquid at a condensing plate to leave the membrane separator. Thus, the separation of the separation mixture can be carried out by means of a membrane separator, resulting in three streams: hydrogen gas stream, liquid water stream, HI and I 2 High temperature mixed gas stream.
The method for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production provided by the embodiment can be implemented according to the following steps:
1) The HIx phase liquid produced by Bunsen reaction is fed into HIx phase purification concentration column 4 to form continuous liquid phase in the column, HI and H from HI decomposition column 6 2 、I 2 And H 2 The O high-temperature mixed gas enters a membrane separator 10, and macromolecules HI and I are separated from the gas 2 (relative H) 2 And H 2 O) cannot leave from the left side of the membrane through the membrane, small molecule H 2 And H 2 O (relative HI and I) 2 ) After passing through the membrane, the water condenses into a liquid at the right side of the membrane and leaves the membrane separator 10, and the hydrogen is output as product via a NaOH wash tank 9. HI and I from Membrane separator 10 2 The high-temperature mixed gas is pressurized by a compressor and then is introduced from the bottom of the HIx phase purification concentration tower 4, the high-temperature mixed gas contacts with HIx phase liquid in the form of bubbles, the vaporization of water is accelerated,at the same time, HIx phase liquid is stirred by air bubbles in a disturbance way, thus avoiding I 2 HI in the high temperature mixed gas is dissolved in the HIx phase liquid (HI is very soluble in water) to increase the HI concentration in the liquid, H in the HIx phase is in an environment of 120-150 DEG C 2 SO 4 The impurity can undergo Bunsen reverse reaction with HI and be converted into H 2 S、SO 2 ：
H 2 SO 4 +8HI＝H 2 S+4I 2 +4H 2 O；
H 2 SO 4 +2HI＝SO 2 +I 2 +2H 2 O。
The temperature in the HIx phase purification concentration tower is maintained at 120-150 ℃, part of heat is from HI and iodine high-temperature gas heat, and the other part of heat is from heat provided by the outside (electric heating and the like), at the temperature, water is evaporated (but not completely evaporated, the inside of the tower is a continuous process, new HIx phase liquid is continuously fed in), and the additional HI gas is dissolved in the water, so that the purpose of concentrating HI solution is achieved.
2) H at high temperature 2 S and SO 2 The solubility in water is very low, and the mixed gas formed by the mixed gas and the vaporized water vapor leaves the HIx phase purification concentration tower 4 to enter the Bunsen reaction tower 2 to enter the next cycle;
3) The mixture of high-concentration HI solution and iodine at the bottom of the HIx phase purification concentration tower 4 enters a microporous filter 5 for cooling, I 2 Filtering to remove HI solution, and decomposing in HI decomposing tower 6 to obtain H 2 And I 2 Unreacted HI and H 2 O enters the membrane separator 10.
The invention is realized by decomposing HI into high-temperature mixed gas (HI and I) 2 ) Pressurized spraying into HIx phase purification concentration tower to stir liquid, thereby preventing I 2 Is deposited. Meanwhile, HI gas is very easy to dissolve in water, and high-temperature mixed gas accelerates the vaporization of water, so that the purpose of improving the concentration of HI solution is achieved. HI and impurity H under high temperature conditions 2 SO 4 Reaction to form SO 2 And H 2 S，SO 2 、H 2 S and H 2 The O mixed gas leaves the HIx phase purification concentration tower (SO at high temperature) 2 And H 2 S is at H 2 The solubility in O is extremely low), and the purpose of purifying the HIx solution is achieved. Coupling the HIx purification section and the concentration section together greatly simplifies the overall system. The heat of the high-temperature gas generated by HI decomposition is integrated into the HIx purification concentration section, so that the energy cascade utilization of the process and the system is realized.
FIG. 2 is a full-flow process of thermochemical sulfur-iodine cycle hydrogen production using the method of the invention, as a typical application case of the invention, the specific flow is as follows: the liquid phase reaction raw material in the Bunsen reaction tower 2 is from a Bunsen premixing tank 1, and the gas phase reaction raw material is from H 2 SO 4 A decomposing column 8 and a HIx phase purification concentration column 4. Allowing the mixture after Bunsen reaction to enter a liquid-liquid separation tower 3 for standing separation, and separating H 2 SO 4 Phase Jing Da side discharge port enters H 2 SO 4 In the concentration column 7, the HIx phase flows from the bottom of the column into the HIx phase purification concentration column 4. Oxygen enters one of the NaOH wash tanks 9 through the top of the Bunsen reactor 2. The Bunsen reaction tower 2 operates at 70-80 deg.c and the reaction is exothermic.
H 2 SO 4 H in concentration column 7 2 SO 4 The phase mixture comes from the liquid-liquid separation column 3, H 2 SO 4 The internal environment of the concentration tower 7 is 100-150 ℃ under normal pressure, and the concentrated sulfuric acid solution enters H 2 SO 4 Decomposition reaction takes place in the decomposition column 8, H 2 SO 4 The operation environment of the decomposing tower 8 is between 850 and 900 ℃ under normal pressure. The resulting high temperature mixed gas leaves from the top of the column and enters the Bunsen reaction column 2.
The HIx phase mixture from the liquid-liquid separation column 3 is treated according to the aforementioned HIx phase purification and concentration method of the present invention, wherein the HIx phase mixture is separated from the high temperature gas (I 2 HI) are met, concentrated and purified, and then leave from the bottom of the tower to enter a microporous filter 5 (the operation environment is 10-20 ℃ and the normal pressure), cooled and filtered to remove I 2 Enters the HI decomposing column 6. Gas (SO) in HIx phase purification concentration column 4 2 ,H 2 S and H 2 O) leaves the column from the upper part and returns to the Bunsen reaction column 2. The internal environment of the HIx phase purification concentration tower 4 is 120-150 ℃ under normal pressure.
The HI solution is sprayed from the bottom of the HI decomposing tower 6, the running environment in the tower is 450-500 ℃ under normal pressure, and the HI decomposing reaction is carried out under the action of the catalyst. The decomposed high-temperature gas mixture leaves from the top of the tower and enters the membrane separator 10, and macromolecules HI and I 2 (relative H) 2 And H 2 O) can not pass through the membrane and leave from the left side of the membrane to be pressurized by a compressor and then be introduced from the bottom of the HIx purification and concentration tower 4; small molecule H 2 And H 2 O (relative HI and I) 2 ) After passing through the membrane, the water condenses into a liquid at the right side of the membrane and leaves the membrane separator 10, and the hydrogen is output as product via a NaOH wash tank 9.
In the whole set of device, iodine-containing liquid temporarily returned by the Bunsen premix tank 1 and water which is replenished at regular time are temporarily stored, and iodine recovered by the microporous filter 5 can be returned to the Bunsen premix tank 1.
Two NaOH wash tanks were used to remove acidic impurities and water from the product gas.
Example 1
The initial temperature in the Bunsen reaction tower is 75 ℃ and the pressure is normal, and the feeding amount in the tower is 18mol H 2 SO 4 ，36 mol HI，18mol SO 2 ,36mol I 2 500mol of water. SO after the reaction 2 The conversion rate reaches 96 percent. The two phases were allowed to stand for 45min to separate.
H 2 SO 4 Phase composition is H 2 SO 4 4.9 mol/kg，HI 0.36 mol/kg，I 2 0.12mol/kg，H 2 O 27.5 mol/kg。H 2 SO 4 Concentration column bottom H 2 SO 4 The concentration reaches 9.4 mol/kg, and concentrated sulfuric acid enters H 2 SO 4 The decomposing tower is used for carrying out decomposition reaction under the action of a catalyst at 850 ℃ and the decomposition rate is more than 96%. Decomposing produced SO 2 、H 2 O and O 2 And a molar ratio of about 2:2:1, the mixed gas leaves from the top of the column and returns to the Bunsen reaction column.
The liquid composition entering the HIx phase purification concentration tower is H 2 SO 4 0.15 mol/kg，HI 1.42 mol/kg，I 2 2.9mol/kg，H 2 O2.7 mol/kg. The liquid phase mixture enters a HIx phase purification concentration column and I from an HI decomposition column 2 High temperature steam of HI400-450 deg.c) meet, and the vaporization of water is accelerated. The temperature in the HIx phase purification concentration tower is controlled at 120 ℃, and the impurity H 2 SO 4 The reaction with HI is as follows:
H 2 SO 4 + 8HI ＝ H 2 S + 4I 2 + 4H 2 O；
H 2 SO 4 +2HI＝SO 2 +I 2 +2H 2 O。
at 120 ℃ H 2 S and SO 2 The liquid level is escaped, and the purpose of purifying HI solution is effectively achieved.
The HI concentration at the bottom of the HIx purification concentration column reaches 1.45 mol/kg, and no H is detected 2 SO 4 In the presence of (1), allowing the concentrated HI solution to enter a microporous filter, cooling to 10 ℃, and cooling to I 2 Filtering to remove, and allowing HI solution to enter into HI decomposition tower, and allowing decomposition reaction at 500deg.C under the action of catalyst with decomposition rate of 22%. Decomposition-generated I 2 And unreacted HI gas and water vapor leave the top of the column and enter the HIx phase purification and concentration column for the next cycle.
Example 2
The initial temperature in the Bunsen reaction tower is 80 ℃ and the pressure is normal, and the feeding amount in the tower is 90mol H 2 SO 4 ，180 mol HI，90mol SO 2 ,180mol I 2 1080mol of water. SO after the reaction 2 The conversion rate reaches 95 percent. The two phases were allowed to stand for 45min to separate.
H 2 SO 4 Phase composition is H 2 SO 4 4.6 mol/kg，HI 0.3mol/kg，I 2 0.07 mol/kg，H 2 O 27.4 mol/kg。H 2 SO 4 Concentration column bottom H 2 SO 4 The concentration reaches 9.4 mol/kg, and concentrated sulfuric acid enters H 2 SO 4 The decomposing tower is used for carrying out decomposition reaction under the action of a catalyst at 800 ℃, and the decomposition rate is more than 95%. Decomposing produced SO 2 、H 2 O and O 2 The molar ratio of (2): 2:1, the outlet temperature was 800 ℃, and the mixed gas was returned to the Bunsen reaction column from the top of the column.
The liquid HIx phase entering the HIx phase purifying and concentrating tower is composed of H 2 SO 4 0.04 mol/kg，HI 1.17 mol/kg，I 2 3.2 mol/kg，H 2 O1.9 mol/kg. The liquid phase mixture enters a HIx phase purification concentration column and is mixed with H from an HI decomposition column 2 ,I 2 And HI high temperature steam (400-450 ℃) are met, and water is carried away by accelerating vaporization. The temperature in the HIx phase purification concentration tower is controlled at 140 ℃. Impurity H 2 SO 4 The reaction with HI is as follows:
H 2 SO 4 + 8HI ＝ H 2 S + 4I 2 + 4H 2 O。
at 140 ℃, H 2 S and SO 2 The liquid level is escaped, and the purpose of purifying HI solution is effectively achieved.
The HI concentration at the bottom of the HIx purification concentration tower reaches 1.45 mol/kg, the concentrated HI solution enters a microporous filter and is cooled to 10 ℃, I 2 Filtering to remove, and allowing HI solution to enter into HI decomposition tower, and performing decomposition reaction at 450deg.C under the action of catalyst with decomposition rate of 22%. Decomposition-generated I 2 And unreacted HI gas and water vapor leave the top of the column and enter the HIx phase purification and concentration column for the next cycle.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the invention.
Claims (10)
1. The method for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production is characterized by comprising the following steps of:
s1: the HIx phase liquid generated by the Bunsen reaction tower is added into a HIx phase purification concentration tower to form a continuous liquid phase in the tower, HI and I from a membrane separator 2 Introducing a high-temperature mixed gas flow from the bottom of the HIx phase purification concentration tower, enabling the high-temperature mixed gas to be in contact with HIx phase liquid in a bubble form, partially vaporizing water in the HIx phase liquid, stirring the liquid mixture by the disturbance of the bubbles, and avoiding I 2 Is dissolved in HIx phase liquid to increase HI concentration in the liquidDegree of H in the HIx phase at the same time 2 SO 4 The impurity undergoes Bunsen reverse reaction with HI and is converted into H 2 S、SO 2 Returns to the Bunsen reaction tower to carry out the reaction,
s2: high concentration HI and I at the bottom of HIx phase purification concentration column 2 The mixed solution enters a microporous filter for cooling, I 2 Filtering to remove HI solution, and decomposing in HI decomposing tower;
s3: delivering the decomposed mixed gas of the HI decomposing tower into a membrane separator, and separating the decomposed mixed gas by the membrane separator to obtain three streams: hydrogen gas stream, liquid water stream, HI and I 2 A high temperature mixed gas stream; wherein HI and I 2 The mixed gas flow returns to the bottom of the HIx phase purification concentration tower, and the hydrogen flow leaves the membrane separator and enters the alkali washing tank to obtain H 2 As a product output.
2. The method for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production according to claim 1, wherein the gas inlet temperature of the HIx phase purifying and concentrating tower is 400-450 ℃, the gas inlet temperature is 120-150 ℃, the gas outlet temperature is 110-120 ℃, and the tower pressure is controlled to be 1bar.
3. The method for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production according to claim 1, wherein the temperature of the HI decomposition tower is 450-500 ℃, and the tower pressure is controlled at 1bar.
4. The method for purifying and concentrating HIx phase of thermochemical sulfur-iodine cycle hydrogen production according to claim 1, wherein in S1, a gas distributor, HI and I are arranged at the bottom of the HIx phase purifying and concentrating tower 2 The high-temperature mixed gas is dispersed by a gas distributor and then enters into HIx phase liquid.
5. The method for thermochemical sulfur-iodine cycling hydrogen production HIx phase purification and concentration according to claim 1, wherein the operating temperature of the microporous filter is 10-20 ℃.
6. According to claimThe method for purifying and concentrating the HIx phase of thermochemical sulfur-iodine cycle hydrogen production, which is characterized in that a silicon dioxide separation membrane is adopted in the membrane separator; macromolecular HI and I 2 Unable to pass through membrane, small molecule H 2 And H 2 O can pass through the membrane, and water after passing through the membrane is condensed into liquid at a condensing plate to leave the membrane separator.
7. An apparatus for thermochemical sulfur-iodine cycling hydrogen production, HIx, phase purification and concentration for performing the process of claim 1, comprising:
a HIx phase purification concentration column comprising at least one liquid phase inlet, one liquid phase outlet, one gas phase inlet and one gas phase outlet; the liquid phase inlet is used for receiving HIx phase liquid obtained by the Bunsen reaction on the upstream of thermochemical sulfur iodine circulation, and the gas phase inlet is connected with the membrane separator and used for receiving HI and I obtained by the separation of the membrane separator 2 A high temperature mixed gas stream; the liquid phase outlet is connected with the microporous filter for discharging high-concentration HI and I 2 The mixed solution, the said gas phase exports and links with Bunsen reaction tower and discharges the mixed gas;
microporous filter for filtering high concentration HI and I 2 I in the mixed solution 2 ；
The HI decomposing tower is connected with the microporous filter, and is used for receiving the HI solution filtered by the microporous filter and decomposing the HI solution;
the membrane separator is used for separating decomposed mixed gas of the HI decomposing tower to obtain three streams: hydrogen gas stream, liquid water stream, HI and I 2 A high temperature mixed gas stream; wherein HI and I 2 The high temperature mixed gas stream is fed to the gas phase inlet of the HIx phase purification concentration column.
8. The apparatus for purifying and concentrating HIx phase of thermochemical sulfur-iodine cycle hydrogen production according to claim 7, wherein a gas distributor is arranged at the bottom of the HIx phase purifying and concentrating column, and the gas distributor is connected with the gas phase inlet.
9. The apparatus for thermochemical sulfur-iodine cycle hydrogen production HIx phase purification and concentration of claim 7 further comprising an alkaline wash tank coupled to the membrane separator for removal of acid gases from the hydrogen stream.
10. The apparatus for purifying and concentrating thermochemical sulfur-iodine cycle hydrogen production HIx phase according to claim 7, wherein the apparatus further comprises a Bunsen reaction column, a liquid-liquid separation column, H 2 SO 4 Concentration tower, H 2 SO 4 A decomposing tower; the Bunsen reaction tower is used as a place where Bunsen reaction occurs, and the liquid-liquid separation tower is used for standing and layering a mixture after Bunsen reaction; h 2 SO 4 The concentration column is used for separating H from the liquid-liquid separation column 2 SO 4 Concentrating the phase mixture; h 2 SO 4 Decomposing tower pair channel H 2 SO 4 The sulfuric acid solution concentrated by the concentration tower is decomposed, and high-temperature mixed gas generated by decomposition enters the Bunsen reaction tower to participate in Bunsen reaction.
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