CN117695963A - System and method for preparing methanol based on oxygen-enriched combustion flue gas - Google Patents
System and method for preparing methanol based on oxygen-enriched combustion flue gas Download PDFInfo
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 174
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 168
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 98
- 239000003546 flue gas Substances 0.000 title claims abstract description 98
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 78
- 239000001301 oxygen Substances 0.000 title claims abstract description 73
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 title claims abstract description 33
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 81
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 78
- 238000010248 power generation Methods 0.000 claims abstract description 59
- 239000007789 gas Substances 0.000 claims abstract description 47
- 238000010521 absorption reaction Methods 0.000 claims abstract description 46
- 239000007788 liquid Substances 0.000 claims abstract description 46
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 45
- 239000001257 hydrogen Substances 0.000 claims abstract description 33
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 33
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 25
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 25
- 238000004458 analytical method Methods 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 239000000446 fuel Substances 0.000 claims description 54
- 230000006835 compression Effects 0.000 claims description 15
- 238000007906 compression Methods 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 9
- 125000000864 peroxy group Chemical group O(O*)* 0.000 claims description 7
- 238000000921 elemental analysis Methods 0.000 claims description 4
- 150000002978 peroxides Chemical class 0.000 claims description 3
- 230000002194 synthesizing effect Effects 0.000 claims description 3
- 230000010354 integration Effects 0.000 abstract description 3
- 230000002411 adverse Effects 0.000 abstract description 2
- 230000000694 effects Effects 0.000 abstract description 2
- 238000004364 calculation method Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000003517 fume Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
Abstract
The application provides a system and a method for preparing methanol based on oxygen-enriched combustion flue gas, wherein the system comprises a combustion power generation unit which generates power by using oxygen-enriched combustion of combustion-supporting mixed gas and outputs combustion flue gas; the carbon capture unit comprises a carbon capture component and a carbon analysis component; carbon captureThe collecting component utilizes the absorption liquid to absorb CO in the residual combustion flue gas 2 Collecting and dissolving; the carbon analysis component is connected with the carbon capture component and is used for dissolving CO 2 Is resolved and the CO separated out 2 Inputting into a mixer; the carbon capture unit of the electrolysis unit is connected with and is dissolved with CO for the rest 2 Is electrolyzed; the CO and hydrogen are fed into a downstream methanol synthesis unit to synthesize methanol. The embodiment realizes the organic integration of the processes of oxygen-enriched combustion, carbon capture, electrolysis and methanol synthesis, simultaneously avoids the adverse effect of higher air leakage rate of the combustion power generation unit on the oxygen-enriched combustion, and realizes the production of green methanol under the condition of no carbon emission.
Description
Technical Field
The application relates to the technical field of combustion flue gas utilization, in particular to a system and a method for preparing methanol based on oxygen-enriched combustion flue gas.
Background
Current atmospheric CO 2 A sharp rise in concentration should beA two-carbon target is put forward for this crisis, and deep carbon emission reduction studies are performed. The power generation industry is the industry with the largest carbon emission, which accounts for nearly 50 percent of the total carbon emission, and is mainly discharged into the air in the form of flue gas. CO2 of the burnt flue gas is captured and then is prepared into chemical industry and energy products, which is an important technical route for solving the carbon emission of the power generation industry. Wherein CO of flue gas 2 The trapping is divided into three processes of pre-combustion trapping, post-combustion trapping and oxygen-enriched combustion, combustion flue gas is mainly generated by both post-combustion trapping and oxygen-enriched combustion, and the air leakage rate of equipment such as a combustion power generation unit and dust removal of a power generation system is high for the oxygen-enriched combustion process, so that great difficulty exists in practical application.
Methanol is not only the basic chemical raw material but also a new energy carrier, so that CO of the combustion flue gas is utilized 2 The methanol prepared after trapping has a feasibility prospect, and the related technical route is as follows: capturing CO in combustion flue gas 2 Methanol is synthesized with hydrogen, but this route has more problems: for example, a place with a large restriction on the application scene must have both a carbon source and a hydrogen source and hydrogen and CO 2 The transportation cost of the (a) is high; CO in combustion flue gas 2 The trapping generally adopts a chemical absorption method, and the energy consumption of an analysis section is relatively high; in addition, the pressure for capturing CO2 by the chemical absorption method is low, and the gas needs to be pressurized when the methanol is synthesized later, so that the control complexity and the power consumption are increased.
Disclosure of Invention
The present application aims to solve, at least to some extent, one of the technical problems in the related art. Therefore, the purpose of the application is to provide a system and a method for preparing methanol based on oxygen-enriched combustion flue gas, wherein the whole system realizes organic integration of oxygen-enriched combustion, carbon capture, electrolysis and methanol synthesis processes, simultaneously avoids adverse effects of high air leakage rate of a combustion power generation unit on oxygen-enriched combustion, and realizes green methanol production under the condition of no carbon emission. Simultaneous combustion of CO in flue gas 2 The concentration is up to 89.5%, and the energy consumption and the cost of carbon capture operation are greatly reduced.
To achieve the above object, the present application proposes a system for preparing methanol based on oxyfuel combustion flue gas, comprising:
the combustion power generation unit generates power by utilizing oxygen-enriched combustion of the combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters the mixer; the combustion-supporting mixed gas is stored in the mixer;
a carbon capture unit comprising a carbon capture component and a carbon resolving component; wherein the carbon capture component utilizes absorption liquid to absorb CO in the residual combustion flue gas 2 Collecting and dissolving; the carbon analysis component is connected with the carbon capture component and is used for dissolving CO 2 Is resolved and the CO separated out 2 Inputting the mixer; the content of the combustion flue gas in the part of absorption liquid is C2;
an electrolysis unit connected to the carbon capture unit and configured to dissolve CO into the remainder 2 Is electrolyzed; oxygen generated by electrolysis is input into the mixer, and CO and hydrogen are input downstream; wherein the content of combustion flue gas in the absorption liquid electrolyzed by the electrolysis unit is C3, and
and a methanol synthesis unit connected to the electrolysis unit and synthesizing methanol from the CO and hydrogen output from the electrolysis unit.
In some implementations, the flow ratio of C1, C2, and C3 is adjusted according to the methanol production and the air leakage rate of the combustion power generation unit.
In some implementations, a compression unit is further included and is respectively connected with the carbon capture assembly and the electrolysis unit and is used for compressing the residual absorption liquid output by the carbon capture assembly, so that the electrolysis unit electrolyzes the absorption liquid to obtain high-pressure synthesis gas composed of CO and hydrogen.
In some implementations, the compression unit pressurizes the absorption liquid to 5-8MPa.
In some implementations, the method of adjusting the ratio of C1, C2, and C3 is:
determining the oxygen concentration s of combustion-supporting mixed gas, the peroxy air coefficient k entering the combustion power generation unit and the air leakage coefficient m of the combustion power generation unit according to the state of the combustion power generation unit;
according to the elemental analysis of the fuel, calculating the theoretical oxygen amount of the unit fuel as Q 0 And combustion per unit fuelFlow rate Q of flue gas c ；
Wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg; C. h, O the percentage content of carbon, hydrogen and oxygen elements of the fuel,%; q (Q) c Flow of combustion flue gas per unit fuel, nm 3 /kg；Q A Combustion-supporting gas mixture amount for unit fuel; q (Q) B Air leakage rate when being used as unit fuel; m is the air leakage coefficient of the combustion power generation unit,%;
calculating process parameters and calculating the proportions alpha, beta and gamma of C1, C2 and C3 by using the following formula;
beta = 1-alpha-gamma; wherein f1, f2, f3, f4 are all process parameters.
In some implementations, in the combustion flue gas C, CO 2 、O 2 And N 2 The concentrations of a1, a2, a3, respectively; wherein a1, a2, a3 are calculated as follows:
in some implementations, f1=1.867×c/Q c ；
f2＝3.76*mQ 0 /Q c ；
f3＝kQ 0 (1/s-1)/Q c +f1；
f4＝kQ 0 /Q c -1.5f1；
Wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg；Q c Flow of combustion flue gas per unit fuel, nm 3 /kg; m is the air leakage coefficient of the combustion power generation unit,%; k is the air ratio of the peroxide entering the combustion power generation unit; total flow of combustion flue gas with unit fuel C, nm 3 /kg。
In some implementations, wherein the combustion power generation unit status determines the oxygen concentration s in the combustion air mixture, the peroxy air coefficient k entering the combustion power generation unit is calculated using the following formula;
kQ 0 ＝Q C *1.5*γ*a1+Q C *α*a2；
wherein Q is c Flow of combustion flue gas per unit fuel, nm 3 /kg；Q 0 Represents theoretical oxygen amount per unit fuel, nm 3 /kg; the proportions α, β, γ of C1, C2 and C3; CO in combustion flue gas C 2 、O 2 And N 2 The concentrations of (a) are a1, a2, a3, respectively.
According to a second aspect of the present application, a method for preparing methanol based on oxyfuel combustion flue gas is presented, the preparation of methanol using the system described in any of the above embodiments comprising:
the combustion power generation unit generates power by utilizing oxygen-enriched combustion of the combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters a mixer; the combustion-supporting mixed gas is stored in the mixer;
the carbon capture component utilizes the absorption liquid to absorb CO in the residual combustion flue gas 2 Capturing CO adsorbed in part of the absorption liquid by the carbon analysis component 2 Analyzing and separating CO 2 Inputting the mixer; wherein the content of the combustion flue gas in part of the absorption liquid is C2;
the electrolysis unit receives the residual absorption liquid to electrolyze to generate oxygen, CO and hydrogen; and inputting oxygen into the mixer, and enabling CO and hydrogen to enter a methanol synthesis unit to synthesize methanol.
In some implementations, the absorption liquid entering the electrolysis unit is pressurized to 5-8MPa with a compression unit, and the ratio of C1, C2, and C3 is adjusted according to the methanol production and the air leakage rate of the combustion power generation unit.
Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic structural diagram of a system for preparing methanol based on oxyfuel combustion flue gas according to an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a system for preparing methanol based on oxyfuel combustion flue gas according to an embodiment of the present disclosure;
FIG. 3 is a schematic view of the distribution of combustion fumes according to another embodiment of the present application;
FIG. 4 is a flow path diagram of components in a system for producing methanol based on oxyfuel combustion flue gas according to an embodiment of the present application;
FIG. 5 is a flow chart of a method for calculating the distribution of combustion flue gas in the preparation of methanol based on oxygen-enriched combustion flue gas according to an embodiment of the present application;
in the figure, 1, a combustion power generation unit; 2. a carbon capture assembly; 3. a carbon resolving component; 4. an electrolysis unit; 5. a methanol synthesis unit; 6. a mixer; 7. and a compression unit.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application. On the contrary, the embodiments of the present application include all alternatives, modifications, and equivalents as may be included within the spirit and scope of the appended claims.
To achieve the above object, the present application proposes a system for preparing methanol based on oxyfuel combustion flue gas, as shown in fig. 1, comprising: a combustion power generation unit 1, a carbon capture unit, an electrolysis unit 4, and a methanol synthesis unit 5; the combustion power generation unit 1 generates power by utilizing oxygen-enriched combustion of combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters the mixer 6; the combustion-supporting mixed gas is stored in the mixer 6.
Wherein the combustion power generation unit 1 utilizes fuel such as coal, biomass and the like, generates power by oxygen-enriched combustion under the combustion supporting condition of combustion supporting mixed gas, and generates combustion flue gas, the total amount of the combustion flue gas is C, wherein CO 2 The concentration is up to 89.5%; wherein the combustion-supporting mixed gas is stored in the mixer 6; the output end of the combustion flue gas of the combustion power generation unit 1 is connected with the mixer 6, and a part C1 in the combustion flue gas enters the mixer 6 and is used for supplementing combustion-supporting mixed gas in the mixer 6. The combustion power generation unit 1 is a common technology in the field, and will not be described in detail.
The carbon capture unit comprises a carbon capture component 2 and a carbon analysis component 3; wherein the carbon capture component 2 utilizes the absorption liquid to absorb CO in the residual combustion flue gas 2 The carbon analysis component 3 is connected with the carbon capture component 2 for capturing CO adsorbed in part of the absorption liquid 2 Analyzing and separating CO 2 An input mixer 6; wherein the content of the combustion flue gas in part of the absorption liquid is C2.
Wherein the carbon capture unit comprises a carbon capture component 2 and a carbon analysis component 3, wherein the carbon capture component 2 is provided with a carbon capture material when containing high-concentration CO 2 Wherein CO is present as the combustion flue gas passes through the carbon capture assembly 2 2 Adsorbed by the carbon trapping material, when the carbon trapping element 2 is charged with an absorbing liquid, such as an absorbing liquid also alkaline absorbing liquid, which can soak the carbon trapping material to remove CO 2 As can be seen from the above, part C1 of the combustion flue gas enters the mixer 6, the residual combustion flue gas amount is the sum of C2 and C3, as shown in fig. 3, and the absorption liquid passes through the carbon capture assembly 2 to capture CO in the combustion flue gas 2 Adsorbing, and discharging other components such as nitrogen, oxygen, etc.; in this embodiment CO will be dissolved 2 The absorption liquid of (2) is divided into two parts, and the first part is introduced into a carbon analysis component 3 for adsorbing CO in part of the absorption liquid 2 Analyzing and separating CO 2 An input mixer 6; wherein the content of the combustion flue gas in part of the absorption liquid is C2; the second portion has a content of C3 of combustion fumes entering the electrolysis unit 4.
The electrolysis unit 4 in the embodiment is connected with the carbon capture unit and receives the residual absorption liquid for electrolysis; the electrolysis unit 4 dissolves CO by electrolysis 2 Is used for producing synthesis gas of CO and hydrogen and oxygen; the electrolytic reaction equation is as follows:
xCO 2 +(1-x)H 2 O→xCO+(1-x)H 2 +0.5O 2
the oxygen generated by electrolysis is input into a mixer 6, and CO and hydrogen are input into a downstream methanol synthesis unit 5; the methanol synthesis unit 5 is connected with the electrolysis unit 4 and synthesizes the CO and the hydrogen output by the electrolysis unit 4 into methanol, wherein H in the synthesis gas 2 : co=2:1, x=1/3. At this time: CO 2 +2H 2 O＝CO+2H 2 +1.5O 2 ；CO+2H 2 ＝CH 3 OH. Therefore, in the embodiment, the three parts of the combustion flue gas output by the combustion power generation unit 1, the C1 part directly enters the mixer 6, and the C2 part is subjected to a complete chemical absorption method to obtain CO 2 Then enters a mixer 6, and the C3 part is subjected to chemical absorption and electrolysis to prepare the synthesis gas. The ratio of the three parts can be adjusted according to the methanol yield and the air leakage rate of the combustion power generation unit 1, and when the air leakage rate is large, the ratio of the C2 part is increased, so that the nitrogen content in the combustion flue gas is reduced, and the CO content is increased 2 Is contained in the composition.
It should be noted that the combustion-supporting gas mixture in this embodiment includes a C1 portion in the combustion flue gas and CO analyzed by the carbon analysis component 3 2 And a small amount of N 2 And O 2 A small amount of N analyzed 2 And O 2 Discharging into the atmosphere; also comprises O electrolyzed by the electrolysis unit 4 2 The method comprises the steps of carrying out a first treatment on the surface of the Thus the combustion-supporting mixed gas comprises CO 2 、O 2 A small amount of N 2 . The combustion-supporting mixed gas replaces air in the combustion power generation unit 1 in the related art, thereby reducing N in combustion flue gas 2 Content and increase of CO in combustion flue gas 2 Is contained in the composition.
In some implementations, a compression unit 7 is further included, which is connected to the carbon capture assembly 2 and the electrolysis unit 4, respectively, for compressing the remaining absorption liquid output from the carbon capture assembly 2, so that the electrolysis unit 4 electrolyzes the absorption liquid to obtain high-pressure synthesis gas composed of CO and hydrogen.
The system for preparing methanol based on oxygen-enriched combustion flue gas also comprises a compression unit 7, as shown in fig. 2, wherein the input end of the compression unit 7 is connected with the carbon capture component 2 and is used for receiving part of absorption liquid, and the content of the combustion flue gas is C3; the absorption liquid is pressurized to 5-8MPa by a compression unit 7 and then is input into an electrolysis unit 4. Wherein the compressed absorption liquid is electrolyzed by an electrolysis unit 4 to obtain high-pressure synthesis gas composed of CO and hydrogen. The known liquid is compressible fluid, so that the compression efficiency is very high; while the gas is a compressible fluid with a compression efficiency of about 50% and a large amount of electrical energy is wasted in the form of thermal energy. Thus, in this embodiment, the absorption liquid is compressed by the compression unit 7, and then the high-pressure synthesis gas is obtained from the downstream electrolysis system. Compared with the scheme of generating the synthesis gas of CO and hydrogen through normal pressure electrolysis in the related art, the scheme of compressing the synthesis gas saves electricity consumption.
The present application solves the limitations of hydrogen sources and carbon sources in the production of methanol from synthesis gas consisting of CO and hydrogen by means of the electrolysis unit 4, and avoids the transportation distance limitation of hydrogen. In addition, due to CO in the related scheme 2 The hydrogenation technology for synthesizing methanol is still not mature, and the technology for preparing methanol from synthesis gas composed of CO and hydrogen is mature, so the embodiment providesThe system for preparing the methanol based on the oxygen-enriched combustion flue gas is safer and more reliable.
In some implementations, the method of adjusting the ratio of C1, C2, and C3 is:
s1, determining oxygen concentration S of combustion-supporting mixed gas, a peroxy air coefficient k entering a combustion power generation unit and an air leakage coefficient m of the combustion power generation unit according to the state of the combustion power generation unit;
s2, calculating theoretical oxygen amount of unit fuel to be Q according to fuel element analysis 0 And flow rate Q of combustion flue gas per unit fuel c ；
Wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg; C. h, O the percentage content of carbon, hydrogen and oxygen elements of the fuel,%; q (Q) c Flow of combustion flue gas per unit fuel, nm 3 /kg；Q A Combustion-supporting gas mixture amount for unit fuel; q (Q) B Air leakage rate when being used as unit fuel; m is the air leakage coefficient of the combustion power generation unit,%;
s3, calculating process parameters and calculating the proportions alpha, beta and gamma of C1, C2 and C3 by using the following formula;
beta = 1-alpha-gamma; wherein f1, f2, f3, f4 are all process parameters.
The fuel element analysis for simplifying the calculation of the combustion power generation unit 1 shown in fig. 4 includes c\h\o\n\s\gray\water, wherein the content of n\s is less, and the gray and water are ignored in the calculation, so that the calculation only considers three elements of c\h\o; meanwhile, the moisture is removed, and only dry basis calculation is performed.
Specifically, by analyzing the process, pushing the process to the combustion flue gas C with the correlation equation, and CO 2 、O 2 And N 2 The concentrations of a1, a2, a3, respectively, are obviously:
a1+a2+a3＝1；(1)
the proportions of C1, C2 and C3 in the combustion flue gas C are alpha, beta and gamma, respectively, obviously:
α+β+γ＝1；(2)
according to the carbon balance of the whole system, C in the fuel is equal to C after electrolysis, and the following can be obtained:
theoretical oxygen amount Q required per unit fuel 0 The calculation mode of (2) is as follows:
wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg; C. h, O the percentages of carbon, hydrogen and oxygen of the fuel, respectively.
In the whole system, N in the air leakage quantity B of the combustion power generation unit 1 is balanced with N in the C2 and C3 flue gas, so that the following conditions are obtained:
the peroxide coefficient entering the combustion power generation unit 1 is k, and the oxygen concentration in the combustion-supporting mixed gas a is s, then there are:
the oxygen source in the combustion-supporting mixed gas A is the oxygen content in C1 and the electrolyzed oxygen in C3 smoke, so
kQ 0 ＝Q C *1.5*γ*a1+Q C *α*a2； (7)
According to the gas flow relation before and after combustion, there are:
wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg; C. h, O the percentage content of carbon, hydrogen and oxygen elements of the fuel,%; q (Q) c Flow of combustion flue gas per unit fuel, nm 3 /kg；Q A Combustion-supporting gas mixture amount for unit fuel; q (Q) B Air leakage rate when being used as unit fuel; m is the air leakage coefficient of the combustion power generation unit,%.
Based on the fuel element analysis data, the theoretical oxygen amount Q can be obtained by the formula (4) 0 Then according to the formula (8), the combustion flue gas flow Q is obtained C . Re-integrating (1), (2), (3), (5), (6), (7) to obtain equation set (9):
wherein f1=1.867×c/Q c ；
f2＝3.76*mQ 0 /Q C ；
f3＝kQ 0 (1/s-1)/Q c +f1；
f4＝kQ 0 /Q c -1.5f1；
A simultaneous equation set (9); can calculate the CO in the combustion flue gas C 2 、O 2 And N 2 The concentrations of a1, a2, a3 and the ratios α, β, γ of C1, C2 and C3, respectively;
β＝1-α-γ；
according to a second aspect of the present application, a method for preparing methanol based on oxyfuel combustion flue gas is presented, the preparing methanol using the system of any of the above embodiments comprising:
s1: the combustion power generation unit 1 generates power by utilizing oxygen-enriched combustion of combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters the mixer 6; the combustion-supporting mixed gas is stored in the mixer 6;
s2: the carbon capture component 2 utilizes the absorption liquid to absorb CO in the residual combustion flue gas 2 Capturing CO adsorbed by the carbon analysis component 3 in part of the absorption liquid 2 Analyzing and separating CO 2 An input mixer 6; wherein the content of the combustion flue gas in part of the absorption liquid is C2;
s3: the electrolysis unit 4 receives the residual absorption liquid for electrolysis to generate oxygen, CO and hydrogen; the oxygen is input into the mixer 6, and the CO and the hydrogen enter the methanol synthesis unit 5 to synthesize the methanol.
In some implementations, the absorption liquid entering the electrolysis unit 4 is pressurized to 5-8MPa by the compression unit 7, and the ratio of C1, C2, and C3 is adjusted according to the methanol yield and the air leakage rate of the combustion power generation unit 1.
The calculation method of the ratio of C1, C2 and C3 is as follows: as shown in figure 5 of the drawings,
s1: determining the oxygen concentration s of combustion-supporting mixed gas, the peroxy air coefficient k entering the combustion power generation unit and the air leakage coefficient m of the combustion power generation unit according to the state of the combustion power generation unit 1;
s2: based on the fuel element analysis, calculating the theoretical oxygen amount of the unit fuel as Q by the formula (4) 0 The method comprises the steps of carrying out a first treatment on the surface of the Calculating the flow Q of the combustion flue gas when the unit fuel is calculated according to the formula (8) c ；
S3: calculating process parameters f1, f2, f3, f4 from equation (9); thus, alpha, beta and gamma are calculated, and the proportion of the smoke in three directions is determined.
Example 1: the molar flow distribution of the combustion-supporting mixed gas, the air leakage quantity and the combustion flue gas is A, B, C. Fuel elemental analysis of the combustion power generation unit 1 in which the proportions of the base carbon element, the base hydrogen element, and the base oxygen element were 68%, 5%, and 7%, respectively. The peroxy air coefficient k entering the combustion power generation unit is 1.3, the air leakage coefficient m of the combustion power generation unit is 0.05, the oxygen concentration s of the combustion-supporting mixed gas is 0.25, and the theoretical oxygen quantity Q of unit fuel is calculated 0 150.0Nm 3 Flow rate Q of combustion flue gas per kg/unit fuel c 792.8Nm 3 /kg; f1 is 0.16, f2 is 0.04, f3 is 0.90, f4 is 0.0058, α is 8.8%, β is 73.3%, γ is 17.9%; CO in flue gas 2 、O 2 N 2 The concentrations a1, a2, a3 of (2) were 89.5%, 6.6%, 3.9%, respectively.
Example 2: fuel elemental analysis of the combustion power generation unit 1 in which the proportions of the base carbon element, the base hydrogen element, and the base oxygen element were 66%, 5%, and 7%, respectively. The peroxy air coefficient k entering the combustion power generation unit is 1.4, the air leakage coefficient m of the combustion power generation unit is 0.04, the oxygen concentration s of the combustion-supporting mixed gas is 0.25, and the theoretical oxygen quantity Q of unit fuel is calculated 0 146.3Nm 3 Flow rate Q of combustion flue gas per kg/unit fuel c At 824.0Nm 3 /kg; f1 is 0.15, f2 is 0.03, f3 is 0.90, f4 is 0.0243, α is 31.1%, β is 52.0%, γ is 16.9%; CO in flue gas 2 、O 2 N 2 The concentrations a1, a2, a3 of (2) were 88.3%, 7.8%, 3.9%, respectively.
The whole system realizes the organic integration of the processes of oxygen-enriched combustion, carbon capture, electrolysis, methanol synthesis and the like, and realizes the production of green methanol under the condition of no carbon emission, thereby greatly reducing the energy consumption and the cost of carbon capture operation.
It should be noted that in the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives, and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.
Claims (10)
1. The system for preparing methanol based on oxygen-enriched combustion flue gas is characterized by comprising:
the combustion power generation unit generates power by utilizing oxygen-enriched combustion of the combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters the mixer; the combustion-supporting mixed gas is stored in the mixer;
a carbon capture unit comprising a carbon capture component and a carbon resolving component; wherein the carbon capture component utilizes absorption liquid to absorb CO in the residual combustion flue gas 2 Collecting and dissolving; the carbon analysis component is connected with the carbon capture component and is used for dissolving CO 2 Is resolved and the CO separated out 2 Inputting the mixer; the content of the combustion flue gas in the part of absorption liquid is C2;
an electrolysis unit connected to the carbon capture unit and configured to dissolve CO into the remainder 2 Is electrolyzed; oxygen generated by electrolysis is input into the mixer, and CO and hydrogen are input downstream; wherein the content of combustion flue gas in the absorption liquid electrolyzed by the electrolysis unit is C3, and
and a methanol synthesis unit connected to the electrolysis unit and synthesizing methanol from the CO and hydrogen output from the electrolysis unit.
2. The system of claim 1, wherein the flow ratio of C1, C2, and C3 is adjusted based on methanol production and the air leakage rate of the combustion power generation unit.
3. The system of claim 1 or 2, further comprising a compression unit connected to the carbon capture assembly and the electrolysis unit, respectively, for compressing the remaining absorption liquid output by the carbon capture assembly such that the electrolysis unit electrolyzes the absorption liquid to obtain a high pressure synthesis gas composed of CO and hydrogen.
4. A system according to claim 3, wherein the compression unit pressurizes the absorption liquid to 5-8MPa.
5. The system of claim 2, wherein the method of adjusting the ratio of C1, C2, and C3 is:
determining the oxygen concentration s of combustion-supporting mixed gas, the peroxy air coefficient k entering the combustion power generation unit and the air leakage coefficient m of the combustion power generation unit according to the state of the combustion power generation unit;
according to the elemental analysis of the fuel, calculating the theoretical oxygen amount of the unit fuel as Q 0 And the flow rate Qc of the combustion flue gas per unit fuel;
wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg; C. h, O the percentage content of carbon, hydrogen and oxygen elements of the fuel,%; flow rate of combustion flue gas Nm when Qc is unit fuel 3 /kg；Q A Combustion-supporting gas mixture amount for unit fuel; q (Q) B Air leakage rate when being used as unit fuel; m is the air leakage coefficient of the combustion power generation unit,%;
calculating process parameters and calculating the proportions alpha, beta and gamma of C1, C2 and C3 by using the following formula;
beta = 1-alpha-gamma; wherein f1, f2, f3, f4 are all process parameters.
6. The system of claim 5, wherein the combustion flue gas C, CO 2 、O 2 And N 2 The concentrations of a1, a2, a3, respectively; wherein a1, a2, a3 are calculated as follows:
7. the system of claim 5 or 6, wherein the system comprises a plurality of sensors,
f1＝1.867*C/Q c ；
f2＝3.76*mQ 0 /Q c ；
f3＝kQ 0 (1/s-1)/Q c +f1；
f4＝kQ 0 /Q c -1.5f1；
wherein Q is 0 Represents the theoretical oxygen amount, nm, required per unit fuel 3 /kg；Q c Flow of combustion flue gas per unit fuel, nm 3 /kg; m is the air leakage coefficient of the combustion power generation unit,%; k is the air ratio of the peroxide entering the combustion power generation unit; total flow of combustion flue gas with unit fuel C, nm 3 /kg。
8. The system of claim 5, wherein the combustion power generation unit status determines the oxygen concentration s in the combustion air mixture, the air-over-oxygen coefficient k entering the combustion power generation unit is calculated using the following formula;
kQ 0 ＝Q C *1.5*γ*a1+Q C *α*a2；
wherein Q is c Flow of combustion flue gas per unit fuel, nm 3 /kg；Q 0 Represents theoretical oxygen amount per unit fuel, nm 3 /kg; the proportions α, β, γ of C1, C2 and C3; CO in combustion flue gas C 2 、O 2 And N 2 The concentrations of (a) are a1, a2, a3, respectively.
9. A method for producing methanol based on oxyfuel combustion flue gas, characterized in that the production of methanol using the system according to any one of the preceding claims 1-8 comprises:
the combustion power generation unit generates power by utilizing oxygen-enriched combustion of the combustion-supporting mixed gas and outputs combustion flue gas, wherein a C1 part in the combustion flue gas enters a mixer; the combustion-supporting mixed gas is stored in the mixer;
the carbon capture component utilizes the absorption liquid to absorb CO in the residual combustion flue gas 2 Capturing CO adsorbed in part of the absorption liquid by the carbon analysis component 2 Analyzing and separating CO 2 Inputting the mixer; wherein the content of the combustion flue gas in part of the absorption liquid is C2;
the electrolysis unit receives the residual absorption liquid to electrolyze to generate oxygen, CO and hydrogen; and inputting oxygen into the mixer, and enabling CO and hydrogen to enter a methanol synthesis unit to synthesize methanol.
10. The method according to claim 9, wherein the absorption liquid entering the electrolysis unit is pressurized to 5-8MPa by the compression unit, and the ratio of C1, C2 and C3 is adjusted according to the methanol yield and the air leakage rate of the combustion power generation unit.
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