WO2013020299A1 - A method for collecting carbon dioxide in mixed gas with composite decarburized solution - Google Patents

Abstract

A method for collecting carbon dioxide in mixed gas with composite decarburized solution. Said composite decarburized solution consists of solvent, main absorbing constituent, assistant absorbing constituent, activated constituent, inhibitor and antioxidant. Wherein the solvent is one or more solvent selected from benzyl alcohol, phenethyl alcohol, N-methyl pyrrolidone, and the main absorbing constituent is selected from monoethanolamine（MEA），and the assistant absorbing constituent is one or more constituent selected from ethylenediamine（EDA）, diethylene triamine（DETA）, triethylene tetraamine（TETA）, and the activated constituent is one or more constituent selected from piperazidine（PZ）, 2，3-diacetyl， and the inhibitor is selected from sodium chromate, as well as the antioxidant is selected from sodium metavanadate and copper carbonate.

Description

 Method for capturing carbon dioxide in mixed gas by using composite decarbonization solution

 Technical field

 The invention belongs to the technical field of gas separation and relates to a method for capturing carbon dioxide in a mixed gas by using a composite decarburization solution.

 Background technique

The greenhouse effect caused by carbon dioxide emissions has caused our planet to be severely affected by the climate. At present, most countries in the world, including China, have signed the "Kyoto Protocol", indicating that controlling carbon dioxide emissions has become a matter of great concern to all countries in the world. At the same time, carbon dioxide is a valuable carbon resource. , can be widely used in machinery, chemicals, food, medicine and other fields, If it can be effectively recycled, it can reduce air pollution and provide us with carbon resources. China's carbon dioxide sources are very rich, but due to the unfavorable measures for recovering carbon dioxide, the amount of carbon dioxide recovered and reused each year is still less than the total emissions. 1%, therefore, the effective solution to the problem of carbon dioxide recycling is imminent. The solvent absorption method for capturing and recovering carbon dioxide is currently the most important method in the industry.

The methods of carbon dioxide capture mainly include solvent absorption method, physical adsorption method, membrane separation method, O ₂ catalytic combustion method and the like. Among them, the chemical solvent absorption carbon dioxide technology is widely used in natural gas, refinery gas, syngas and flue gas. In order to further improve the absorption capacity of the absorbent, reduce the corrosiveness, reduce the loss due to volatilization and the energy consumption during regeneration, people have been working hard to develop an efficient chemical solution absorbent. After years of research, a single group has been started. The high-energy-absorbing absorbent has developed into a low-energy absorbent for the composite component, and the composition and content of the absorbent are still the focus of scholars.

The Chinese patent (CN 103855A) of 1985 discloses a method for removing carbon dioxide from a gas mixture, the absorbent being K ₂ CO ₃ 15-30%, diethanolamine 10-30 g/l, and glycine 10-20 g/ l, boric acid 15-30 g / liter, total vanadium (calculated as KVO ₃ ) 5-10 g / liter. Its solution has a capacity to absorb CO ₂ of 21-26 NM ³ CO ₂ /M ³ solution.

 1999, US patent (US09, 329, 259 Disclosed is a method for absorbing carbon dioxide from a feed gas, which absorbs carbon dioxide from a feed gas in a composite solution, preferably a composite solvent containing a small concentration of one or more fast reaction rate amines (MEA or DEA) The mass fraction is 5% to 35%) and the higher concentration of one or more slow reaction rate amines (MDEA mass fraction is 5% to 50%).

In 2001, U.S. Patent No. 6,290,754 B1 discloses a method of removing carbon dioxide from a mixed gas by adding an active component to an MDEA amine solution. The MDEA concentration is 1-6 mol/L. The active component is H ₂ NC _n H _2n -NH-CH ₂ -CH ₂ OH , (1 ≤ n ≤ 4), and its concentration is between 0.01 and 0.5 of the molar concentration of the total amine.

 2002, Chinese patent (CN 1340374A A composite decarburization solution for removing carbon dioxide from a gas is disclosed. The weight percentage of gas amine is composed of the following materials: A. 30~50% MDEA, B.0.1~1.5% dimethylethanolamine, C. 0.5~1.5% methylethanolamine, D.1~2% dinitrogen ring, E. The rest is water.

Its solution has a capacity to absorb CO ₂ of 22-26 NM ³ CO ₂ /M ³ solution.

 2007, Chinese patent (CN 101053751A A composite decarburization solution for recovering carbon dioxide from exhaust gas is disclosed. The composition and mass percentage of the composite solution are as follows: composite ammonia solution 20~60% Which contains a lower concentration of one or more of the fast reaction rate amine and a higher concentration of one or more slow reaction rate amine; polyalcohol ether 5~10%; antioxidant 1~5%; corrosion inhibitor 1~5% The rest is water.

 In 2007, Korean patent (KR 10, 2007, 0097560 A mixed absorbent for separating carbon dioxide is disclosed, the absorbent comprising 100 parts by weight of the compound of the formula 1 and 1 to 60 parts by mass of the formula 2 heterocyclic compound having at least one amino group on the ring, wherein The compound of the formula contains a hydroxyl group and a primary amino group, having no substituent adjacent to the amino alpha carbon position, and the alkyl substituent and the alcohol hydroxyl substituent are on the beta carbon.

 In summary, the main application of MEA, DEA, etc. as the main absorbent, to MDEA In addition to assisting absorption, with a variety of active components with strong absorption capacity and preservatives, corrosion inhibitors and other decarbonizing aqueous solutions, although their respective advantages, but their comprehensive decarburization capacity is generally low, renewable energy The consumption is high, the solvent circulation is large, the equipment is corrosive, and the economic benefits cannot be optimized, so there is still room for improvement.

 Summary of the invention

The invention provides a method for capturing carbon dioxide in a mixed gas by using a composite decarburization solution, solving the problems of low decarburization ability of the decarburization solution, high regeneration energy consumption, and better CO ₂ recovery under low pressure conditions. effectiveness.

 The technical solution adopted by the present invention to solve the technical problem thereof is:

 The composite decarburization solution of the present invention is mainly composed of a solvent, a main absorption component, a auxiliary absorption component, an active component, a corrosion inhibitor and an antioxidant. The solvent used was benzyl alcohol, phenethyl alcohol, N-methylpyrrolidone, and a mixture thereof. The main absorption component is monoethanolamine (MEA) to MEA As the main absorption component, the absorption rate is fast, the absorption amount is large, the desorption temperature is low, but the corrosion is slightly higher; the absorption absorption components include ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA). ), these three substances can be used alone or in combination. The added auxiliary absorption component mainly increases the absorption load of the solvent and lowers the desorption temperature. Since the absorption amount of the auxiliary absorbent is greatly affected by the temperature, it decreases with the increase of the temperature, and thus the temperature changes with the absorption reaction. The amount of absorption also changes; the active component is mainly composed of Piperazine (PZ) and 2,3-butanedione are used. The two substances may be used singly or in combination. Mainly activates the main absorbent and the auxiliary absorbent to increase the reaction rate and absorption, so as to quickly reach saturation; in order to reduce the corrosion of the absorption liquid and the degradation of the absorption liquid, the composite decarburization liquid is simultaneously added with corrosion inhibition. Agent, The corrosion inhibitor is sodium chromate; the antioxidant is sodium metavanadate and copper carbonate.

The above-mentioned composite decarburization solution for capturing carbon dioxide in the mixed gas may have a total solvent ratio of 0 to 80% by mass of the composite decarburization solution. The main absorbent component (MEA) can be used in a mass percentage of 10 to 40%. The sum of the auxiliary absorption components can be used in a percentage by mass of 5% to 30%. The sum of the active components can be used in a percentage by mass of from 1% to 10%. The corrosion inhibitor can be used in a mass percentage of 0.05% to 1.0%. The percentage of antioxidants taken from the source is 0.05% to 1.0%.

The invention has the effects and benefits that the novel composite decarburizing solution of the present invention is capable of trapping a volume fraction of carbon dioxide in a mixed gas of 2% to 90%, and has a solution of 50 to 70 Nm ³ CO ₂ /m ³ per hour. a large absorption amount, a higher amount of desorbed _{^{35 ~ 50Nm 3 CO 2 / m}} 3 solution, and desorption begins at 70 ~ 9 0 ℃, fully desorbing at 60min. However, the traditional solution using water as a solvent has a low absorption and desorption amount, and it takes about 90 minutes to completely desorb. Therefore, the present invention is suitable for recovering carbon dioxide in various chemical reaction tail gas, combustion flue gas, ore decomposition gas, natural gas, gas, and biogas. The greatest feature of the present invention is the use of benzyl alcohol, phenylethyl alcohol, N-methylpyrrolidone or mixtures thereof without the use of conventional water as a solvent. Since the conventional solution absorbs carbon dioxide, the desorption temperature is generally higher than 100 ° C, and higher than the normal boiling point of water, the water as a solvent evaporates to cause a large amount of thermal energy loss, so the present invention uses high boiling point benzyl alcohol, Phenylethanol, N-methylpyrrolidone or a mixture thereof is not easy or even non-volatile during regeneration, greatly reducing the consumption of regenerative heat energy.

 DRAWINGS

 Figure 1 is a graph of absorption and desorption of a mixture of 200 g of 40% MEA and phenylethyl alcohol.

detailed description

 The preferred embodiments are described in detail below in conjunction with specific examples to provide basic data for their industrial applications.

 Example

200g of a mixture of MEA with a total amine mass content of 40% and a phenylethyl alcohol content of 60% as an absorption solution, charged into a 500 ml reactor equipped with a constant temperature oil bath stirrer at a temperature of 40 ° C At a flow rate of 0.012 M ³ /h, a CO ₂ pressure of 0.2 MPa and a concentration of 99% was introduced, and continuous measurement was performed by a wet anti-corrosion flowmeter, thereby calculating the absorption rate, absorption amount and absorption load of carbon dioxide. After the solution reached saturation, the oil bath temperature was set to 120 ° C for desorption, and the total desorption amount and desorption rate were measured. After three absorption desorption tests, the stability was observed (see the attached drawing).

 By way of example, in the absence of water, the amount of solution absorbed is slightly reduced, but the desorption rate is fast, and the saturated carbon dioxide absorption liquid is at 120. When desorbing at °C, the desorption rate decreases as the reaction time increases. Moreover, each of the examples undergoes three absorption and desorption, and the amount of absorption is similar, which is stable, and can be industrially applied.

In summary, the carbon dioxide absorbing solution of the present invention has a good absorption and desorption effect. Especially in the desorption process, due to the use of a new mixed solvent benzyl alcohol, phenylethyl alcohol, N- Methylpyrrolidone or a mixture thereof, under the premise that the total desorption amount is not reduced, the amount of volatilization of the solvent at the time of absorption is reduced, the absorption rate is improved, the energy consumption of the absorption and regeneration is greatly reduced, and the use of the volatile solvent is also reduced. The amount of cooling water can increase economic efficiency. And after three times of absorption and desorption, the absorbent still has a good effect, so the invention has a good industrial application prospect.

Claims (1)

1. A method for capturing carbon dioxide in a mixed gas by using a composite decarburizing solution, the decarburizing solution being composed of a solvent, a main absorbing component, a absorbing component, an activating component, a corrosion inhibitor and an antioxidant; The solvent is one or more of benzyl alcohol, phenethyl alcohol and N-methylpyrrolidone, the main absorption component is monoethanolamine (MEA), and the auxiliary absorption component is ethylenediamine (EDA) or diethylenetriamine ( One or more of DETA) and triethylenetetramine (TETA), the active component is one or more of piperazine (PZ) and 2,3-butanedione, and the corrosion inhibitor is chromium. Sodium, the antioxidant is sodium metavanadate and copper carbonate.

2. The method of claim 1 wherein the solvent comprises from 0 to 80% by mass of the composite decarburization solution.

3. The method of claim 1 wherein the mass percentage of the primary absorbent component (MEA) is from 10 to 40%.

4. The method of claim 1 wherein the mass percentage of the absorbing component is from 5% to 30%.

5. The method according to claim 1, wherein the mass percentage of the active component is from 1% to 10%.

6. The method according to claim 1, wherein the corrosion inhibitor has a mass percentage of 0.05% to 1.0%.

7. The method according to claim 1, wherein the mass percentage of the antioxidant is from 0.05% to 1.0%.

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