CN103897758A

CN103897758A - Equipment and method for producing synthesized gas with low H2/CO ratio

Info

Publication number: CN103897758A
Application number: CN201310726935.3A
Authority: CN
Inventors: 白俊铉; 刘永敦; 姜锡焕; 高东准; 金晋号; 金秀贤; 柳在洪
Original assignee: Research Portfolio Institute Of Advanced Technology; Research Institute of Industrial Science and Technology RIST
Current assignee: Research Portfolio Institute Of Advanced Technology; Research Institute of Industrial Science and Technology RIST
Priority date: 2012-12-26
Filing date: 2013-12-25
Publication date: 2014-07-02
Also published as: AU2013270551A1; KR20140085671A; AU2013270551B2; KR101429973B1

Abstract

The present invention discloses a piece of equipment and method for producing synthesized gas with low H2/CO ratio. The invention provides the production of SNG equipment, including: the first synthesis of SNG device and the second SNG synthesis device, the H2 / CO concentration ratio of 0.60.95 synthesis gas. There is also provided a method for the production of SNG, including: the first SNG synthesis and SNG synthesis of second, H2 / CO concentration which is supplied to the first SNG synthesis gas in the synthetic process is 0.60.95. Synthesis gas supply will have low H2 / CO concentration ratio to the first SNG synthesis process, at the same time caused by water soluble phenoxy resin and methane synthesis reaction. Therefore, without water gas shift process additional. In addition, the first in the synthesis process of SNG supply steam, without processfor recirculation control reaction temperature, whichcan produce SNG with low cost.

Description

Using low H2Device and method for producing synthetic natural gas from synthesis gas with/CO ratio

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from korean patent application No. 10-2012-0153905, filed from korean patent office at 26/12/2012, the entire contents of which are incorporated herein by reference.

Background

The invention relates to the use of low H₂Plant and process for the production of Synthetic Natural Gas (SNG) from synthesis gas at a/CO concentration ratio.

Since coal is abundant throughout the world relative to other fuel sources, much research has been done globally to convert coal into SNG, a cleaner fuel.

Can be produced by gasification, dust collection, purification or CO₂The removal process yields a synthesis gas containing mainly carbon monoxide and hydrogen from e.g. coal or biomass containing a large amount of carbon. SNG can then be obtained by subjecting such syngas to a methane synthesis process.

Methods for producing SNG from coal include a direct method in which hydrogen or high-temperature steam is directly converted into methane by reacting the coal and hydrogen, and an indirect method in which synthesis gas is produced by a reaction between coal and oxygen and converted into SNG through a methane synthesis process.

Fig. 1 is a schematic diagram showing a typical indirect method in the related art. SNG12 may be produced from coal 1 (raw material) by the following process: the coal 1 is processed through processes such as a gasification process 4, a dust collection process 6, a water gas shift process 7, an acid gas (sulfur compounds) and carbon dioxide removal process, and a methane synthesis process, and in the water gas shift process 7, the concentration ratio of hydrogen and carbon monoxide is controlled.

[ background Art document ]

(patent document 1) Korean patent application laid-open No. 10-2004-0015790

(patent document 2) U.S. patent publication No. 2009/0173081

(patent document 3) U.S. patent publication No. 2009/0264542

Referring to fig. 1, in a gasification process 4, coal 1 is supplied together with oxygen 2, and organic substances contained in the coal are converted into a synthesis gas while inorganic substances such as dust and slag 3 are continuously removed. After processing the syngas by a heat collecting process 5 and a dust collecting process 6, H in the syngas is converted in a water gas shift process 7₂The concentration ratio of CO is adjusted to 3:1 and sulfur compounds and carbon dioxide are removed from the syngas in an acid gas and carbon dioxide removal process 8 10. In the methane synthesis process 9, synthesis gas having a concentration of hydrogen and carbon monoxide of greater than or equal to 99% is converted to methane, and the methane is processed by a drying and compression process 11 to obtain SNG 12.

In most SNG processes of the related art, H is converted by a water gas shift process₂The concentration ratio of/CO is adjusted to be greater than or equal to 3.0, and most of CO is treated by the acid gas treatment process₂Together with the sulfur-containing compounds. Thereafter, the synthesis gas is supplied to each methane synthesis reactor to control the reaction temperature of the methane synthesis reactor, or an amount of gas discharged from the first or second methane synthesis reactor is compressed and recycled to control the first or second methane synthesis reactorReaction temperature of the dimethane synthesis reactor. In this way, deactivation of the catalyst is suppressed.

However, if H is not paired₂If the concentration ratio of CO is controlled or the temperature of the reactor is maintained at a temperature of greater than or equal to about 650 c to 700 c, the nickel-containing catalyst is deactivated during SNG at a process pressure of typically 20atm, and thus high concentrations of SNG may not be produced.

Furthermore, since the cost of the compressor for recycling used in many processes accounts for tens of percent of the total cost of the equipment of the SNG synthesis process, there is a need for an improved SNG synthesis method that does not employ a compressor.

SUMMARY

Some aspects of the invention provide apparatus and methods for producing Synthetic Natural Gas (SNG) by blending a synthetic natural gas with a low H content₂The synthesis gas of the/CO concentration ratio is supplied to the reactor together with steam to control the internal temperature of the reactor and to increase the concentration of SNG without a recycling process since the water gas shift reaction and the methane synthesis reaction simultaneously occur in the reactor.

According to one aspect of the present invention, an apparatus for producing SNG includes: a first SNG synthesis unit and a second SNG synthesis unit containing a methane synthesis catalyst, the first SNG synthesis unit configured to receive steam and H-containing₂CO and CO₂And discharging a methane-containing gas produced by the methane synthesis reaction; the second SNG synthesis unit is configured to receive the methane-containing gas and discharge SNG produced by a methane synthesis reaction, wherein H of the syngas₂The concentration ratio of/CO is 0.6-0.95.

The first SNG synthesis plant may include 2-4 reactors.

Steam may be supplied to each reactor of the first SNG synthesis plant.

The apparatus can also include a heat exchanger configured to exchange heat with the methane-containing gas exiting the first SNG synthesis unit to produce steam.

According to another aspect of the invention, a method for producing SNG comprises: performing a first SNG synthesis process in which H is contained₂CO and CO₂Is supplied together with steam to simultaneously initiate a water gas shift reaction and a methane synthesis reaction, and a methane-containing gas is discharged; and performing a second SNG synthesis process in which the methane-containing gas is supplied for producing SNG by a methane synthesis reaction and SNG is discharged, wherein H of the synthesis gas supplied in the first SNG synthesis process₂The concentration ratio of/CO is 0.6-0.95.

The first SNG synthesis process can be performed 2-4 times.

The steam to carbon monoxide volume ratio supplied during the first SNG synthesis may be in the range of 2 to 5.

The steam may be generated by a heat exchange process utilizing methane-containing gas discharged during the first SNG synthesis.

The first SNG synthesis process may be performed at a reaction temperature of 300 ℃ to 680 ℃.

The second SNG synthesis process may be performed at a reaction temperature of 250 ℃ to 350 ℃.

Drawings

The above and other aspects, features and other advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic flow diagram of a typical indirect process of the related art;

fig. 2 is a schematic diagram of a plant for producing Synthetic Natural Gas (SNG) according to an exemplary embodiment of the present invention.

Fig. 3 is a schematic flow chart for explaining a method of producing SNG according to an exemplary embodiment of the present invention;

FIG. 4 is a schematic diagram showing the temperature change in the first SNG synthesis unit based on the volume ratio of steam to carbon monoxide;

FIG. 5 is a schematic representation of the percent conversion of carbon monoxide in the first SNG synthesis unit of example 3; and

fig. 6 is a graph showing the percent conversion of carbon monoxide in the first SNG synthesis unit in example 4.

Detailed Description

Exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

FIG. 2 is a schematic diagram of a plant for producing Synthetic Natural Gas (SNG) according to an exemplary embodiment of the present invention; fig. 3 is a schematic diagram illustrating a method for producing SNG according to an exemplary embodiment of the present invention. An embodiment of the present invention will be described below with reference to fig. 2 and 3.

Apparatus of exemplary embodiments of the present invention are provided to employ a system having a low H₂Syngas 10 at a/CO concentration ratio to produce SNG. Specifically, the apparatus comprises: a first SNG synthesis unit containing a methane synthesis catalyst configured to receive steam 20 and H-containing H together, and a second SNG synthesis unit 180₂CO and CO₂And discharging the methane-containing gas produced by the methane synthesis reaction; the second SNG synthesis unit 180 is configured to receive the methane-containing gas and discharge SNG80 produced by the methane synthesis reaction, wherein H of the syngas 10₂The concentration ratio of/CO is 0.6-0.95.

The method of the exemplary embodiments of the present invention is provided to employ a material having a low H₂Syngas 10 at a/CO concentration ratio to produce SNG. In particular, the method comprises: performing a first SNG synthesis process in which H is contained₂CO and CO₂Is supplied together with steam 20 to simultaneously initiate a water gas shift reaction and a methane synthesis reaction, and a methane-containing gas is discharged; and performing a second SNG synthesis process in which the methane-containing gas is supplied for producing SNG80 by a methane synthesis reaction and SNG80 is discharged, wherein H of the synthesis gas 10 supplied in the first SNG synthesis process₂The concentration ratio of/CO is 0.6-0.95.

The plant may include a first SNG synthesis unit to receive syngas 10 and synthesize methane. The syngas 10 may be produced by a coal gasification process, and the syngas 10 may have a low H since it has not undergone a water gas conversion process₂The ratio of the concentration of the catalyst to the concentration of CO. For example, H of syngas 10₂the/CO concentration ratio may be in the range of 0.6 to 0.95. However, the embodiments of the present invention are not limited thereto. Therefore, if it is to have a low H₂The synthesis gas 10 having the/CO concentration ratio is supplied to the first SNG synthesis apparatus, the water gas shift reaction and the methane synthesis reaction can simultaneously occur as the first SNG synthesis process. A methane-containing gas may be discharged from the first SNG synthesis unit as a result of the water gas shift reaction and the methane synthesis reaction.

Further, the volume ratio of steam 20 to carbon monoxide supplied to the first SNG synthesis unit during the first SNG synthesis process may be in the range of 2 to 5. If the volume ratio of steam 20 to carbon monoxide is less than 2, coking may occur with the water gas shift reaction and the methane synthesis reaction, which may cause deactivation of the methane synthesis catalyst and increase the reactor pressure, thereby decreasing the yield of methane synthesis. If the volume ratio of steam 20 to carbon monoxide is greater than 5, an excess of steam 20 may result in a decrease in the competitiveness of the first SNG synthesis process in terms of economy.

The first SNG synthesis apparatus may comprise a plurality of SNG synthesis reactors connected in series. The number of reactors is not limited. For example, the number of reactors may be 2-4. An adiabatic reactor may additionally be connected to increase the selectivity and yield of the final methane product.

Steam 20 may be fed to the first SNG synthesis unit along with syngas 10. In this case, steam 20 may be supplied to each reactor of the first SNG synthesis plant. In the related art, the methane-containing gas discharged from the reactor is recycled to increase the yield of methane synthesis and control the reaction temperature. However, the recycling equipment is expensive. According to the embodiment of the present invention, the temperature of the reactor is controlled by supplying the steam 20 to each reactor, so that the cost required for the recycling apparatus can be saved to improve the economical aspect. The steam 20 may be generated by a heat exchange process utilizing methane-containing gas discharged from the reactor of the first SNG synthesis plant. To this end, in this embodiment, the SNG production facility may further include a heat exchanger 140 configured to exchange heat with the methane-containing gas discharged from the reactor of the first SNG synthesis unit.

The reaction temperature of the first SNG synthesis unit, i.e., the reaction temperature of the first SNG synthesis process, may be adjusted to be in the range of 300 ℃ to 680 ℃ by supplying the steam 20. However, the present embodiment is not limited thereto. As shown in fig. 2, if the first SNG synthesis unit of the SNG production facility includes first to third reactors 110, 120 and 130 (3 reactors), the reaction temperatures of the first to third reactors may be adjusted to be in the ranges of 300 ℃ to 680 ℃, 300 ℃ to 510 ℃ and 300 ℃ to 365 ℃, respectively. However, the present embodiment is not limited thereto. If the reaction temperature of the reactor of the first SNG synthesis unit falls outside the above range, the methane synthesis catalyst may undergo coking or sintering, resulting in deactivation of the catalyst and reverse water gas shift reaction, and as a result, the conversion percentage and yield of methane synthesis may decrease.

The methane-containing gas exiting the first SNG synthesis unit may be treated to remove water 90 and carbon dioxide 100 therefrom before being supplied to the second SNG synthesis unit 180 to increase the yield of methane synthesis. The methane-containing gas may then be compressed to a pressure suitable for supply via a natural gas pipeline. For this, the SNG production facility of the present embodiment may further include a condenser 150, a carbon dioxide removing device 160, and a compressor 170. The compressor 170 may compress the methane-containing gas to a pressure of 50-70atm, and then may supply the methane-containing gas to the second SNG synthesis unit 180. However, the present embodiment is not limited thereto.

The methane-containing gas may be supplied to a second SNG synthesis unit 180 to perform a second SNG synthesis process to produce SNG80 through a methane synthesis reaction. The methane concentration of SNG80 may be greater than or equal to 95%. However, the present embodiment is not limited thereto. Further, the condenser 150 may remove moisture in the SNG80 discharged from the second SNG synthesizing device.

The following will explain embodiments of the present invention. However, the present invention is not limited to these examples.

Example 1

SNG is produced using the SNG production apparatus of the embodiment of the present invention. At 4,905Nm³Rate per hour H₂The synthesis gas with a concentration ratio/CO of 0.93 was fed to the first reactor of the first SNG synthesis plant. The amounts and concentrations of the materials in the various units and reactors are shown in table 1, with the reference numbers of figure 2 being used to indicate the material flows.

[ Table 1]

As shown in table 1, the methane concentration of the methane-containing gas discharged from the reactor of the first SNG synthesis apparatus was 14.00 mol%, 27.54 mol%, and 34.1 mol%, respectively, and after water and carbon dioxide were removed from the methane-containing gas and the methane-containing gas was compressed, the methane concentration of the methane-containing gas increased to 90.47 mol%. The methane concentration of the final SNG produced and dehydrated by the second SNG synthesis unit was 97.50 mol%. That is, SNG having a methane concentration of 95% or more can be produced using the SNG production facility of the embodiment of the present invention.

Example 2

Synthesis gas (H) containing 2g of a nickel-containing catalyst (available from S-C, Sud-Chemie) and having a carbon dioxide concentration of 22% was used at 20atm and 360 deg.C₂/CO concentration ratio = 0.93) to produce SNG. The synthesis gas was supplied to the reactor while decreasing the volume ratio of steam to carbon monoxide in the synthesis gas by 4.0, 2.5 and 2.0 in this order, and the internal temperature of the reactor was measured. The measured temperature values are shown in fig. 4.

As shown in fig. 4, when the steam to carbon monoxide volume ratio of the syngas was 2.0, the internal temperature of the reactor was maintained at 360 ℃. Under this condition, the water gas shift reaction and the methane synthesis reaction occur, and the internal temperature of the reactor is maintained at 360 ℃ due to the reaction heat. However, since the volume ratio of steam to carbon monoxide is 2.0, the catalyst is deactivated by coking during the water gas shift reaction and the methane synthesis reaction, and as a result, the internal pressure of the reactor is increased. Therefore, it may be preferred that the volume ratio of steam to carbon monoxide is greater than 2.0. Furthermore, if the H of the synthesis gas is₂If the/CO concentration ratio is greater than 0.93, the steam to carbon monoxide ratio will decrease. In FIG. 4, TC-1 to TC-5 refer to temperatures measured from an upper catalyst layer to a lower catalyst layer in a reactor at intervals of 20 mm.

Example 3

SNG was produced under the same conditions as in example 2, except that the volume ratio of steam to carbon monoxide was 2.5, and the space velocity was maintained at 7,000ml/g catalyst hour. The percent conversion of carbon monoxide to carbon dioxide and methane in the first SNG synthesis unit was measured as shown in fig. 5.

As shown in fig. 5, the water gas shift reaction and the methane synthesis reaction continued to be stable for 42 hours. Percent conversion of carbon monoxide is 100%: 48.7% of the carbon monoxide is converted to carbon dioxide and 51.3% of the carbon monoxide is converted to methane.

Example 4

SNG was produced under the same conditions as in example 2, except for the following conditions: 1g of a nickel-containing catalyst (from S-C); the volume ratio of steam to carbon monoxide was 2.5; and the space velocity was maintained at 32,500ml/g catalyst hour. The percent conversion of carbon monoxide to carbon dioxide and methane in the first SNG synthesis unit was measured as shown in fig. 6.

As shown in fig. 6, the water gas shift reaction and the methane synthesis reaction continued to stabilize for 620 hours. Percent conversion of carbon monoxide 96.59%: 48.24% of the carbon monoxide is converted to carbon dioxide and 48.35% of the carbon monoxide is converted to methane.

As described above, according to exemplary embodiments of the present invention, in an apparatus and method for producing SNG, it will have a low H₂The synthesis gas of the/CO concentration ratio is supplied to the first SNG synthesis process to initiate both the water-soluble phenoxy resin and the methane synthesis reaction. Thus, no additional water gas shift process may be required. Further, since steam is supplied in the first SNG synthesis process, it is possible to dispense with a recycling process for controlling the reaction temperature, so that SNG can be produced at low cost.

While exemplary embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An apparatus for producing Synthetic Natural Gas (SNG), the apparatus comprising:

a first SNG synthesis unit containing a methane synthesis catalyst configured to receive steam and H-containing₂CO and CO₂And discharging a methane-containing gas produced by the methane synthesis reaction; and

a second SNG synthesis unit configured to receive the methane-containing gas and to discharge SNG produced by the methane synthesis reaction,

wherein,h of the synthesis gas₂The concentration ratio of/CO is 0.6-0.95.

2. The apparatus of claim 1, wherein the first SNG synthesis unit comprises 2-4 reactors.

3. The apparatus of claim 2, wherein steam is supplied to each reactor of the first SNG synthesis plant.

4. The apparatus of claim 1, further comprising a heat exchanger configured to exchange heat with methane-containing gas exiting the first SNG synthesis unit to produce steam.

5. A method of producing SNG, comprising:

performing a first SNG synthesis process in which H is contained₂CO and CO₂Is supplied together with steam to simultaneously initiate a water gas shift reaction and a methane synthesis reaction, and a methane-containing gas is discharged; and

performing a second SNG synthesis process in which the methane-containing gas is supplied to produce SNG through a methane synthesis reaction and SNG is discharged,

wherein H of the synthesis gas supplied in the first SNG synthesis process₂The concentration ratio of/CO is 0.6-0.95.

6. The method of claim 5, wherein the first SNG synthesis process is performed 2-4 times.

7. The method of claim 5, wherein the steam to carbon monoxide volume ratio supplied during the first SNG synthesis is in the range of 2 to 5.

8. The method of claim 5, wherein the steam is generated by a heat exchange process utilizing methane-containing gas vented during the first SNG synthesis.

9. The method of claim 5, wherein the first SNG synthesis process is performed at a reaction temperature in a range of 300 ℃ to 680 ℃.

10. The method of claim 5, wherein the second SNG synthesis process is performed at a reaction temperature of 250 ℃ to 350 ℃.