KR20130130972A - Method for high purity hydrogen generation - Google Patents

Abstract

The present invention is a method for continuously producing high purity hydrogen from a synthesis gas generated by gasification of hydrocarbon fuel by a recovery enhanced water gas shift (SEWGS) using an aqueous gasification catalyst and a carbon dioxide adsorbent. The first step of supplying the synthesis gas obtained by the gasification of the fuel and in contact with the aqueous gasification catalyst and carbon dioxide adsorbent in the fluidized state to promote hydrogen production by reducing the partial pressure of carbon dioxide due to the adsorption of carbon dioxide in the synthesis gas ; A second step of moving the water gasification catalyst and the carbon dioxide adsorbent while separating gaseous hydrogen generated in the first step; A third step of separating and discharging carbon dioxide adsorbed on the carbon dioxide adsorbent by contacting the regeneration gas to the aqueous gasification catalyst and the carbon dioxide adsorbent; And a fourth step of returning the aqueous gasification catalyst and the regenerated carbon dioxide adsorbent to the first step, wherein the first to fourth steps are sequentially and sequentially performed.

Description

Method for High Purity Hydrogen Generation

The present invention relates to a high-purity hydrogen production method, and more particularly, recovery enhanced gas gas (SEWGS) using an aqueous gasification catalyst and a carbon dioxide adsorbent from a synthesis gas generated by gasification of hydrocarbon fuel. It relates to a method for continuously producing high purity hydrogen by the reaction.

Research is being actively carried out to use hydrogen as a clean fuel in preparation for depletion of fossil fuels. Extensive research is being carried out on infrastructure construction for the hydrogen economy society, fuel cell buses, fuel cells for power generation, and hydrogen storage have.

Such hydrogen production is mainly studied in fossil fuels. Steam reforming technology is used to produce carbon dioxide and hydrogen by reacting hydrocarbons, which are fossil fuels, with water, and separating generated carbon dioxide to obtain hydrogen, gasification of hydrocarbons And a technique for producing hydrogen by a water gas shift reaction from a syngas generated by a gas-phase synthesis gas (syngas).

Thus, in the process of producing hydrogen from fossil fuels, carbon dioxide is generated, and the purity of the received hydrogen differs depending on the degree of separation of generated carbon dioxide. On the other hand, since carbon dioxide is a greenhouse gas that causes global warming, it is very important to produce high purity hydrogen and to separate carbon dioxide.

Particularly, although the technology for producing hydrogen using the water gasification conversion reaction is disclosed in Korean Patent Application No. 10-2009-072726, it is required to undergo a two-stage aqueous gasification reaction of high temperature aqueous gasification and low temperature aqueous gasification, There is a problem that energy is wasted.

SUMMARY OF THE INVENTION An object of the present invention devised to solve the above problems is a method of continuously producing high purity hydrogen by a recovery enhanced water gas shift (SEWGS) reaction using an aqueous gasification catalyst and a carbon dioxide adsorbent. To provide.

The present invention for achieving the above object, by supplying the synthesis gas obtained by gasification of hydrocarbon fuel and in contact with the aqueous gasification catalyst and carbon dioxide adsorbent in the fluidized state through the reduction of the partial pressure of carbon dioxide due to the adsorption of carbon dioxide in the synthesis gas A first step of promoting hydrogen production; A second step of moving the water gasification catalyst and the carbon dioxide adsorbent while separating gaseous hydrogen generated in the first step; A third step of separating and discharging carbon dioxide adsorbed on the carbon dioxide adsorbent by contacting the regeneration gas to the aqueous gasification catalyst and the carbon dioxide adsorbent; And a fourth step of returning the aqueous gasification catalyst and the regenerated carbon dioxide adsorbent to the first step, wherein the first to fourth steps are sequentially and sequentially performed.

In the fourth step, the carbon dioxide adsorbent is cooled to a carbon dioxide adsorption temperature.

In addition, steam is supplied together with the synthesis gas in the first step.

In the third step, the regeneration gas is composed of at least one selected from carbon dioxide and steam.

In addition, the water gasification catalyst may be made of any one or more selected from CuO, ZnO, MoO ₃ , Al ₂ O ₃ and a complex thereof and a mixture of these materials and the support, the carbon dioxide adsorbent K ₂ CO ₃ , KHCO ₃ , MgO, hydrotalcite, a complex thereof, and a mixture of these materials and a support.

The second step is characterized in that made by the flow rate of the additionally supplied moving gas. Therefore, it is possible to adjust the movement amount of the water gasification catalyst and the carbon dioxide adsorbent by the flow rate of the moving gas. The moving gas may be steam or carbon dioxide gas.

The first step is characterized in that the first flow rate and the second flow rate faster than the primary flow rate is made sequentially.

At this time, the first flow rate and the second flow rate is changed by changing the cross-sectional area of the flow reactor in which the first stage is made, or by syngas, steam, or a mixture thereof supplied to the intermediate portion of the flow reactor. Differential and secondary flow rates can be given.

Through the present invention, not only can continuously produce high purity hydrogen, but also produce carbon dioxide as a by-product. In addition, compared to the existing process consisting of cooling, high temperature water gas conversion, cooling, low temperature water gas conversion, and carbon dioxide separation recovery, the size of the device can be significantly reduced, and the catalyst cost can be reduced by using only one type of water gasification catalyst. have.

1 is a schematic diagram of a high purity hydrogen production process according to the present invention.
2 is a schematic diagram of a hydrogen production apparatus constructed in accordance with a method for producing high purity hydrogen according to the present invention.
FIG. 3 is a graph of weight percent of each component according to the time of the outlet of the water gasification reactor when only the water gasification catalyst is used in the water gasification reactor.
FIG. 4 is a graph of weight percent of each component according to the time of the outlet of the water gasification reactor when the water gasification catalyst and the carbon dioxide adsorbent are used in the water gasification reactor.

Hereinafter, the present invention will be described with reference to the drawings and examples. In the drawings, the same reference numerals are used to designate the same or similar components, and the same reference numerals will be used to designate the same or similar components. Detailed descriptions of known functions and configurations are omitted.

The present invention relates to a process for the production of hydrocarbon fuel, The main feature is to promote the water gasification reaction by reducing the partial pressure of carbon dioxide through the immobilization of carbon dioxide in order to produce hydrogen at a high concentration from the synthesis gas. In addition, the carbon dioxide adsorbent can be used repeatedly by regeneration for the continuity of the process.

Accordingly, the present invention provides a first step of carbon dioxide adsorption and hydrogen generation, a second step of water gasification catalyst and carbon dioxide adsorbent movement, a third step of regenerating carbon dioxide adsorbent, and a water gasification catalyst to continuously provide immobilization of carbon dioxide. And a fourth step of returning the carbon dioxide adsorbent to the basic configuration.

The first step is a step of supplying the synthesis gas obtained by gasification of the fuel and in contact with the aqueous gasification catalyst and carbon dioxide adsorbent in the fluidized state to promote hydrogen production by reducing the partial pressure of carbon dioxide due to the adsorption of carbon dioxide in the synthesis gas. .

The components included in the synthesis gas are H ₂ , CO, CO ₂ , CH ₄ , H ₂ O, etc. Among them, when carbon monoxide (CO), which is a main component, is reacted with water vapor, water gasification reaction (or water gas transition reaction) as in Scheme 1 Hydrogen is produced by water gas shift reaction, and carbon dioxide is generated together.

[Reaction Scheme 1]

CO + H ₂ O? CO ₂ + H ₂

Accordingly, as shown in FIG. 1, the synthesis gas and the steam are simultaneously supplied, and the mixed gas of the synthesis gas and the steam serves as the fluidizing gas. The steam flow rate can be supplied from 1 to 10 times the syngas flow rate.

At this time, in the process mainly aiming at the production of hydrogen, it is preferable that the partial pressure of CO ₂ is low in accordance with the principle of Re-Chatlli in order for the positive reaction of the reaction formula 1 to actively take place. In the present invention, a carbon dioxide adsorbent of a metal oxide was used to lower the partial pressure of CO ₂ . The process of adsorption of carbon dioxide by the metal oxide is shown in Reaction Scheme 2.

[Reaction Scheme 2]

CO ₂ + MO - > MCO ₃

Therefore, when the reaction of Scheme 1 and Scheme 2 occurs at the same time, the reaction occurs as shown in Scheme 3 below. Thus, when the CO ₂ in the gas is immobilized on the carbon dioxide adsorbent which is a solid particle, the partial pressure of CO ₂ in the gas decreases. Because of the preponderance of hydrogen reaction (hydrogen production), the hydrogen yield can be increased, and high purity hydrogen can be received. However, because the water-based gasification and CO ₂ absorption reaction by the CO ₂ absorbent by the catalyst up simultaneously, the operating temperature range in the range 150 ~ 300 ℃ that can occur both reactions.

Scheme 3

CO + H ₂ O + MO - H ₂ + MCO ₃

The water gasification catalyst may be made of any one or more selected from CuO, ZnO, MoO ₃ , Al ₂ O ₃ and a complex thereof and a mixture of these materials and a support, and the carbon dioxide adsorbent is K ₂ CO ₃ , KHCO ₃ , MgO , hydrotalcite, a complex thereof, and a mixture of these materials and a support.

The first step may be sequentially performed at a primary flow rate and a secondary flow rate that is higher than the primary flow rate. That is, in the first flow rate section, the carbon dioxide adsorbent and the water gasification catalyst have a flow rate below the terminal velocity. In the first flow rate section, a water gasification reaction and a carbon dioxide adsorption reaction occur, and in the second flow rate section. Aqueous gasification catalyst and carbon dioxide adsorbent are scattered to move upward. This may provide sufficient time for the water gasification catalyst and carbon dioxide adsorbent to contact steam and syngas, and at the same time facilitate the movement of the water gasification catalyst and carbon dioxide adsorbent to the second stage.

At this time, the change of the primary flow rate and the secondary flow rate may be made by changing the cross-sectional area of the flow reactor, or by syngas, steam, or a mixed gas thereof supplied in the middle of the flow reactor. In the former case, the cross-sectional area of the primary flow rate section is formed larger than that of the secondary flow rate section. In the latter case, additional gas supply lines may be installed in the flow reactor. It is also possible to simultaneously change the cross-sectional area of the flow reactor and install additional gas supply lines.

The hydrogen concentration according to the first step is compared with the prior art as follows.

[Comparative Example]

ShiftMax210, a commercial catalyst, is used as an aqueous gasification catalyst, and the synthesis gas supplied is composed of 28 wt% H ₂ , 63 wt% CO, and 9 wt% CO ₂ . In addition, the weight of steam supplied is 3 times the weight of CO. In addition, a cylindrical water gasification reactor having a length of 1.6 m and an inner diameter of 0.15 m maintains a pressure of 17 bar and a temperature of 210 ° C.

As a result, as shown in FIG. 3, 52.2% by weight of H ₂ , 0.92% by weight of CO, and 46.88% by weight of CO ₂ were obtained as average values at the outlet of the water gasification reactor.

[Test Example]

The same as Comparative Example, ShiftMax210 and a carbon dioxide adsorbent (K ₂ CO ₃ ) at the same time was used together, there is a difference that the mixture of the two particles is continuously circulated between the recovery and regeneration gasifier and the regeneration reactor.

As a result, as illustrated in FIG. 4, 97.86 wt% of H ₂ , 2.01 wt% of CO, 0.06 wt% of CO ₂ , and 0.07 wt% of CH ₄ were obtained as average values at the outlet of the water gasification reactor.

Therefore, when the water gasification catalyst and the carbon dioxide adsorbent are used at the same time as in the first step, the hydrogen production is greatly increased, and the carbon dioxide is adsorbed on the carbon dioxide adsorbent and is significantly reduced.

Next, the second step is to move the aqueous gasification catalyst and carbon dioxide adsorbent while separating the gaseous hydrogen generated in the first step.

Separation of hydrogen may use a cyclone, and the movement of the water gasification catalyst and the carbon dioxide adsorbent may be performed by the pressure of the fluidization gas. Since the gas released through the cyclone is a mixture of hydrogen and H ₂ O, high concentration of hydrogen can be obtained by removing H ₂ O by condensation.

However, the pressure of the fluidizing gas may be lowered due to the discharge of hydrogen gas and steam, and the amount of the required water gasification catalyst and carbon dioxide adsorbent is changed depending on the amount of the syngas supplied. Therefore, the present invention proposes to use a separate moving gas for the movement of the water gasification catalyst and carbon dioxide adsorbent. As the moving gas, carbon dioxide gas or steam may be used. In addition, a roof chamber or a buffer tank may be used to provide a space for temporarily storing the water gasification catalyst and the carbon dioxide adsorbent.

In the third step, the regeneration gas is contacted with the aqueous gasification catalyst and the carbon dioxide adsorbent to separate and release the carbon dioxide adsorbed on the carbon dioxide adsorbent. Steam or carbon dioxide gas is used as the regeneration gas. The reaction occurring in the third step is the reverse reaction of the reaction formula 2 as shown in the reaction formula 4. At this time, since the carbon dioxide adsorbent can separate carbon dioxide only at a temperature higher than the first step, the regeneration gas is higher than the temperature of the water gasification catalyst and the carbon dioxide adsorbent supplied through the second step.

[Reaction Scheme 4]

MCO ₃ → MO + CO ₂

Thus, the carbon dioxide adsorbent which adsorbs CO ₂ is discharged to the CO ₂ by the regeneration reaction, such as the scheme 4, and reduced to the original form of the metal oxide. At this time, the generated carbon dioxide may be released separately from the water-based gasification catalyst and carbon dioxide adsorbent in the solid state by a cyclone or the like. In the third step, a mixture of CO ₂ or CO ₂ and H ₂ O is discharged, so that by removing H ₂ O by condensation, a high concentration of CO ₂ can be obtained. Since the carbon dioxide adsorbent must be regenerated by heat in the third step, it is operated at a higher temperature than the first step, and in order to minimize the thermal shock applied to the water gasification catalyst, it is operated at 300 to 600 ° C.

Finally, the fourth step is to return the aqueous gasification catalyst and the regenerated carbon dioxide adsorbent to the first step. At this time, the carbon dioxide adsorbent should be cooled to the carbon dioxide adsorption temperature, and a separate cooling device or pretreatment reactor may be used for this purpose. The cooling device is simply a heat exchange mechanism, which cools the aqueous gasification catalyst and the regenerated carbon dioxide adsorbent through endotherm. The pretreatment reactor supplies a pretreatment gas (for example, steam) at a lower temperature than the third stage to cool the aqueous gasification catalyst and the carbon dioxide adsorbent.

As described above, through the processes of the first to fourth steps circulating the water gasification catalyst and the carbon dioxide adsorbent, it is possible to continue to produce high purity hydrogen, and at the same time to produce carbon dioxide as a by-product.

In addition, since the water gasification transition reaction and the CO ₂ adsorption reaction in the first step is an exothermic reaction, and the regeneration reaction of the CO ₂ adsorbent in the third step is an endothermic reaction, heat extraction is performed in the first step for a smooth process. However, a heat supply is required. Heat extraction in the first step may be controlled by the temperature of the steam or a separate cooling means may be installed around the reactor. In addition, in the third step, the heat supply may be made of steam, or a separate heating means may be installed around the reactor.

2 is a schematic view of a hydrogen generator according to the hydrogen production method described above. The hydrogen generating apparatus basically comprises an aqueous reactor 1, a first cyclone 2, a loop chamber 3, a regeneration reactor 4, and a second cyclone 5 known in the prior art.

The aqueous reactor 1 may be a known fluidized bed reactor, the synthesis gas and steam is supplied to the lower side of the aqueous reactor (1). In particular, as shown in FIG. 2, the velocity of the fluidizing gas can be increased by narrowing the cross section area of the upper part of the upper part compared to the lower part of the lower part. Further, in order to increase the speed of the fluidizing gas, steam or the like can be additionally supplied between the high speed portion and the low speed portion of the aqueous reactor 1.

The first cyclone (2) is a known apparatus, by centrifuging the carbon dioxide adsorbent adsorbed the aqueous gasification catalyst and carbon dioxide in the aqueous reactor (1), the aqueous gasification catalyst and carbon dioxide adsorbent as solid particles A falling, light gas, ie a gas comprising hydrogen, is fed to the subsequent stage via the first cyclone 2.

The roof chamber 3 is a well-known device, and is installed to prevent gas mixing of the aqueous reactor 1 and the regeneration reactor 4 and to control the circulation rate of the solid particles. As the moving gas, carbon dioxide gas or steam may be used. Can be.

In the regeneration reactor 4, the carbon dioxide adsorbent that has adsorbed carbon dioxide is heated to allow the carbon dioxide adsorbent to release carbon dioxide. At this time, the heating temperature of the carbon dioxide adsorbent is higher than the reaction temperature of the aqueous reactor (1). In the regeneration reactor 4, heating of the solid absorbent is performed in a fluidized state by regeneration gas supplied from the outside, and steam or carbon dioxide gas may be used as the regeneration gas. When steam is used, pure carbon dioxide can be obtained by removing only water from the regenerated gas.

The second cyclone 5 is connected to the regeneration reactor 4. This is to prevent the loss of the water gasification catalyst and carbon dioxide adsorbent suspended by the regeneration gas. The structure of the second cyclone 5 is basically the same as the first cyclone 2.

The aqueous gasification catalyst and carbon dioxide adsorbent that have passed through the regeneration reactor 4 are returned to the aqueous reactor 1. At this time, a cooling device for cooling the water gasification catalyst and the carbon dioxide adsorbent may be further installed between the regeneration reactor 4 and the aqueous reactor 1.

The cooling device may use a method of cooling by using a heat exchanger by indirect contact or by directly supplying a pretreatment gas to a pretreatment device (not shown) having a predetermined space and contacting the aqueous gasification catalyst and the carbon dioxide adsorbent. As the pretreatment gas, an inert gas such as nitrogen gas may be used. The temperature of the pretreatment gas should be at least equal to or lower than the injection temperature of the syngas or steam supplied to the aqueous reactor 1. The pretreatment gas can rapidly cool the solid adsorbent in the pretreatment apparatus by performing a fluidized bed motion of the solid adsorbent in the same manner as the regeneration reactor (4). In this case, a separate cyclone should be attached to the pretreatment device to prevent the loss of the water gasification catalyst and carbon dioxide adsorbent.

The dry solid adsorbent which adsorb H ₂ O is further nopyige the adsorption rate of the carbon dioxide due to the nature that the carbon dioxide is readily soluble in H ₂ O. Therefore, it is preferable to supply the pretreatment gas in a state of saturated steam to humidify the solid adsorbent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It can be understood that

1: aqueous reactor 2: first cyclone
3: loop chamber 4: regeneration reactor
5: second cyclone

Claims (12)

Supplying the synthesis gas obtained by gasification of the fuel and simultaneously contacting the aqueous gasification catalyst and the carbon dioxide adsorbent in a fluidized state to promote hydrogen generation by reducing the partial pressure of carbon dioxide due to adsorption of carbon dioxide in the synthesis gas;
A second step of moving the water gasification catalyst and the carbon dioxide adsorbent while separating gaseous hydrogen generated in the first step;
A third step of separating and discharging carbon dioxide adsorbed on the carbon dioxide adsorbent by contacting the regeneration gas to the aqueous gasification catalyst and the carbon dioxide adsorbent; And
A fourth step of returning the aqueous gasification catalyst and the regenerated carbon dioxide adsorbent to the first step,
Wherein the first step to the fourth step are sequentially performed successively.
The method of claim 1, wherein in the fourth step, the carbon dioxide adsorbent is cooled to a carbon dioxide adsorption temperature.
The method of claim 1, wherein steam is supplied together with the synthesis gas in the first step.
The method according to claim 1, wherein the regeneration gas in the third step comprises at least one selected from carbon dioxide and steam.
The method of claim 1, wherein the aqueous gasification catalyst comprises at least one selected from the group consisting of CuO, ZnO, MoO ₃ , Al ₂ O ₃ and a complex thereof, and a mixture of these materials and a support.
The method of claim 1, wherein the carbon dioxide adsorbent comprises at least one selected from K ₂ CO ₃ , KHCO ₃ , MgO, hydrotalcite, a complex thereof, and a mixture of these materials and a support.
The high purity hydrogen production method according to claim 1, wherein the second step is performed by a pressure of the additionally supplied moving gas.
The high purity hydrogen production method according to claim 7, wherein the flow rate of the water gasification catalyst and the carbon dioxide adsorbent is adjusted by the flow rate of the moving gas.
The method of claim 8, wherein the moving gas is steam or carbon dioxide gas.
The method of claim 1, wherein the first step is performed at a first flow rate and at a second flow rate faster than the first flow rate.
The method of claim 10, wherein the primary flow rate and the secondary flow rate are imparted by changing the cross-sectional area of the flow reactor in which the first step is performed.
11. The high purity of claim 10, wherein the first flow rate and the second flow rate are imparted by syngas, steam, or a mixture of these gases, which is additionally supplied to an intermediate portion of the flow reactor in which the first step is performed. Hydrogen Production Method.

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