1. The utility model provides a direct liquefaction entrapment system of carbon dioxide under supercritical pressure, includes one-level cooling kettle, absorption tower, GAX heat exchanger, regenerator, desulphurization unit, second grade cooling kettle and liquid carbon dioxide basin, its characterized in that:

a) the first-stage cooling kettle is connected with the absorption tower, a raw material gas inlet is arranged on the absorption tower, a circulating pipe is arranged between the cooling kettle and the absorption tower, the first-stage cooling kettle is provided with a cooling water inlet pipe and a cooling water outlet pipe, a purified gas exhaust pipe is arranged on the absorption tower, the pressure of the raw material gas inlet is 0.1-10 MPa, the raw material gas is one or a mixture of more of industrial tail gas, flue gas or pure carbon dioxide with lower pressure,

b) the absorption tower is connected with the regeneration tower through a first liquid guide pipe, a second liquid guide pipe is connected between the regeneration tower and the circulating pipe, a GAX heat exchanger is arranged between the first liquid guide pipe and the second liquid guide pipe,

c) the regeneration tower is connected with the secondary cooling kettle through a third liquid guide pipe, a desulfurization device is arranged on the third liquid guide pipe,

d) the secondary cooling kettle is connected with a fourth liquid guide pipe, and the fourth liquid guide pipe is connected with a liquid carbon dioxide storage tank.

2. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 1, wherein: the circulating pump is arranged on the circulating pipe.

3. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 2, wherein: the first liquid guide pipe is provided with a liquid conveying pump, and the second liquid guide pipe is provided with a valve.

4. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 3, wherein: the regeneration tower is internally provided with a heat source inlet pipe and a heat source outlet pipe, a first heat exchange device is arranged between the heat source inlet pipe and the heat source outlet pipe, the pressure range of the regeneration tower is 0.15-15 MPa, the heat source used for desorption is preferably waste heat or a heat source supplied by heat and power, and the temperature is 100-350 ℃.

5. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 4, wherein: and a second heat exchange device is arranged on the secondary cooling kettle.

6. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 5, wherein: the upper end of the second heat exchange device is connected with the third liquid guide pipe, and the lower end of the second heat exchange device is connected with the fourth liquid guide pipe.

7. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 6, wherein: and a refrigerant liquid inlet pipe and a refrigerant liquid outlet pipe are arranged on the secondary cooling kettle.

8. The system for direct liquefaction capture of carbon dioxide at supercritical pressure of claim 7, wherein: the refrigerant can be a natural cold source, air, cooling water or a cooling working medium from a refrigerating unit.

9. A method for directly liquefying and capturing carbon dioxide under supercritical pressure is characterized by comprising the following steps: the system of claim 1 to 8, wherein a raw material gas containing carbon dioxide is introduced into an absorption tower, an absorption liquid is arranged in the absorption tower, the absorption liquid absorbs the carbon dioxide in the raw material gas, in the process, the absorption liquid is circularly cooled by a primary cooling kettle, the tail gas of the absorbed raw material gas is discharged through a purified gas exhaust pipe and reserved for subsequent treatment, the absorption liquid absorbing the carbon dioxide enters a regeneration tower, under the condition of continuously introducing a heat source, the absorption liquid decomposes the carbon dioxide after passing through a first heat exchange device and then enters a circulating pipe through a second liquid guide pipe, in the process, the second liquid guide pipe exchanges heat with the first liquid guide pipe through a GAX heat exchanger, the sulfur in the carbon dioxide generated in the regeneration tower is removed by a desulfurization device when passing through a third liquid guide pipe and then enters a secondary cooling kettle, and exchanges heat with a refrigerant in the secondary cooling kettle through a second heat exchange device, cooling and liquefying under supercritical pressure, and storing in a liquid carbon dioxide storage tank.

10. The method for direct liquefaction capture of carbon dioxide at supercritical pressure as claimed in claim 9, wherein: the absorption liquid can be one or a plurality of alcohol-ammonia mixtures and ammonia water mixtures, the heat source introduced into the heat source inlet pipe can be one or a plurality of smoke, steam, dead steam and CHP energy sources, the absorption liquid formula contains alkalescent absorbent, surfactant, preservative and the like, the main active ingredients are organic amine and alcohol amine, and the substance ratio of the two mechanisms is as follows: 60-95% of organic amine and 5-40% of alcohol amine, and further optimized according to actual operation conditions.

Background

Carbon Capture and Storage (CCS, also known as Carbon Capture and sequestration, Carbon collection and Storage, etc.) refers to a technique for collecting Carbon dioxide (CO2) produced by large power plants and storing it in various ways to avoid its emission into the atmosphere. This technology is considered to be the most economical and feasible method for reducing greenhouse gas emission and alleviating global warming on a large scale in the future. In 2012, 8 and 6, the project that the first carbon dioxide is stored in the saline water layer in China is broken through.

The CCS technology can be divided into three steps of capture, transportation and sequestration, commercial carbon dioxide capture has been operated for a while, the technology has developed to be mature, and the carbon dioxide sequestration technology is still being experimented in large scale in various countries.

There are three main ways of capturing carbon dioxide: pre-combustion capture (Pre-combustion), Oxy-fuel combustion (Oxy-fuel combustion), and Post-combustion capture (Post-combustion).

In industry, the carbon dioxide is liquefied in the later stage of the traditional carbon dioxide capture by adopting a compression mode, namely the carbon dioxide is liquefied after capture by multi-stage compression, and a high-power electric compressor is used, so that a capture system is huge and a large amount of energy is consumed.

In order to solve the problem of carbon capture, the application refers to a waste heat refrigeration related unit, and refers to a patent CN201711364115.9, and proposes a system and a method for directly liquefying and capturing carbon dioxide under supercritical pressure, which are used for solving the problems in the existing carbon dioxide capture process.

Disclosure of Invention

The present invention is directed to a system and method for collecting carbon dioxide in supercritical pressure for direct liquefaction, which solves the above problems of the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: including one-level cooling kettle, absorption tower, GAX heat exchanger, regenerator, desulphurization unit, second grade cooling kettle and liquid carbon dioxide basin, its characterized in that: the first-stage cooling kettle is connected with the absorption tower, a raw material gas inlet is formed in the absorption tower, a circulating pipe is arranged between the cooling kettle and the absorption tower, the first-stage cooling kettle is provided with a cooling water inlet pipe and a cooling water outlet pipe, a purified gas exhaust pipe is arranged on the absorption tower, the pressure of the raw material gas inlet is 0.1-10 MPa, the raw material gas is industrial tail gas, flue gas or pure carbon dioxide with lower pressure or a mixture of a plurality of gases, the absorption tower is connected with the regeneration tower through a first liquid guide pipe, a second liquid guide pipe is connected between the regeneration tower and the circulating pipe, a GAX heat exchanger is arranged between the first liquid guide pipe and the second liquid guide pipe, the regeneration tower is connected with the second-stage cooling kettle through a third liquid guide pipe, a desulfurization device is arranged on the third liquid guide pipe, the second-stage cooling kettle is connected with a fourth liquid guide pipe, and the fourth liquid guide pipe is connected with a liquid carbon dioxide storage tank.

Preferably, the circulation pipe is provided with a circulation pump.

Preferably, the first liquid guide pipe is provided with a liquid conveying pump, and the second liquid guide pipe is provided with a valve.

Preferably, a heat source inlet pipe and a heat source outlet pipe are arranged in the regeneration tower, a first heat exchange device is arranged between the heat source inlet pipe and the heat source outlet pipe, the pressure range of the regeneration tower is 0.15-15 MPa, the heat source for desorption is preferably waste heat or a heat source for combined heat and power supply, and the temperature is 100-350 ℃.

Preferably, the second heat exchange device is arranged on the second-stage cooling kettle.

Preferably, the upper end of the second heat exchange device is connected with the third liquid guide pipe, and the lower end of the second heat exchange device is connected with the fourth liquid guide pipe.

Preferably, a refrigerant liquid inlet pipe and a refrigerant liquid outlet pipe are arranged on the secondary cooling kettle.

Preferably, the refrigerant can be a natural cold source, air, cooling water or a cooling working medium from a refrigerating unit.

Preferably, the absorption liquid can be one or a combination of more of alcohol ammonia mixture and ammonia water mixture, the heat source introduced into the heat source inlet pipe can be one or more of smoke, steam, dead steam and CHP energy source stations, the absorption liquid formula contains alkalescent absorbent, surfactant, preservative and the like, the main active ingredients are organic amine and alcohol amine, and the substance ratio of the two mechanisms is as follows: 60-95% of organic amine and 5-40% of alcohol amine, and further optimized according to actual operation conditions.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the scheme, the carbon dioxide is captured by the one-step method, compared with a two-step method of firstly supplementing and then compressing in the prior art, the energy consumption of the electric compressor is reduced, only part of heat is consumed, the low-grade heat is used for capturing the carbon dioxide, and energy conservation and emission reduction are realized.

2. The carbon dioxide of this scheme is in high-pressure state itself in the regenerator, is higher than the critical pressure of carbon dioxide, and carbon dioxide under this state has better heat transfer performance, and the heat transfer is easier, consequently in the secondary cooling cauldron, the refrigerant only needs the temperature to be less than critical temperature 31.2 degrees centigrade, if take waste heat refrigerating unit to supply with the refrigerant, will greatly improve carbon dioxide liquefaction efficiency.

3. In the scheme, the heat source can be supplied to the regeneration tower and can also be supplied to the waste heat refrigerating unit in series, and the prepared cold energy can be used for liquefying the final carbon dioxide, so that the energy utilization rate is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present invention provides a technical solution: a system and a method for directly liquefying and capturing carbon dioxide under supercritical pressure comprise a primary cooling kettle, an absorption tower, a GAX heat exchanger, a regeneration tower, a desulfurization device, a secondary cooling kettle and a liquid carbon dioxide storage tank, and are characterized in that: the first-stage cooling kettle is connected with the absorption tower, a raw material gas inlet is arranged on the absorption tower, a circulating pipe is arranged between the cooling kettle and the absorption tower, a cooling water inlet pipe and a cooling water outlet pipe are arranged on the first-stage cooling kettle, a purified gas exhaust pipe is arranged on the absorption tower, the absorption tower is connected with the regeneration tower through a first liquid guide pipe, a second liquid guide pipe is connected between the regeneration tower and the circulating pipe, a GAX heat exchanger is arranged between the first liquid guide pipe and the second liquid guide pipe, the regeneration tower is connected with the second-stage cooling kettle through a third liquid guide pipe, a desulfurization device is arranged on the third liquid guide pipe, the second-stage cooling kettle is connected with a fourth liquid guide pipe, and the fourth liquid guide pipe is connected with a liquid carbon dioxide storage tank. The low-grade heat is used for capturing carbon dioxide, so that energy is saved and emission is reduced.

The circulating pipe is provided with a circulating pump, the first liquid guide pipe is provided with a liquid conveying pump, the second liquid guide pipe is provided with a valve, the regeneration tower is internally provided with a heat source inlet pipe and a heat source outlet pipe, a first heat exchange device is arranged between the heat source inlet pipe and the heat source outlet pipe, the second-stage cooling kettle is provided with a second heat exchange device, the upper end of the second heat exchange device is connected with a third liquid guide pipe, the lower end of the second heat exchange device is connected with a fourth liquid guide pipe, the second-stage cooling kettle is provided with a refrigerant liquid inlet pipe and a refrigerant liquid outlet pipe, and carbon dioxide is in a high-pressure state in the regeneration tower and, therefore, in the secondary cooling kettle, the temperature of the refrigerant is only required to be lower than the critical temperature of 31.2 ℃, liquid carbon dioxide can be obtained, if a waste heat refrigerating unit is adopted to supply a refrigerant, the temperature of cooling water can be greatly reduced, and the liquefaction efficiency of the carbon dioxide is further improved.

The desorption (regeneration) pressure is related to the subsequent condensation temperature (generally the ambient temperature), preferably a low-temperature natural cold source, such as cooling water, wet air cooling and the like (below 30 ℃), and the condensation and desorption pressure is between the near-critical and the supercritical (preferably in the range of 2.5-10MPa), so that the desorbed carbon dioxide is directly liquefied in one step; the heat source used for desorption is preferably waste heat or a heat source supplied by combined heat and power, the temperature is 100-; the formula of the absorbent mainly considers the requirements of lower desorption temperature and lower energy consumption under higher pressure, the formula contains a weakly alkaline absorbent, a surfactant, a preservative and the like, the main active ingredients of the absorbent mixture related by the disclosure are organic amine and alcohol amine, and the material proportion of two mechanisms of balanced absorption capacity and absorption rate is as follows: 60-95% of organic amine and 5-40% of alcohol amine, and further optimized according to actual operation conditions (waste heat/heat source temperature, raw material components and the like).

The regenerated absorption liquid returns to the front of the absorption tower, heat is transferred to the carbon-rich solution from the absorption tower through a heat exchanger, and then (a) pressure work is recovered and reduced through a hydraulic turbine, or (b) pressure work passes through an ejector, or (c) the pressure work reaches the absorption tower after a + b, so that the full utilization of internal waste heat and residual pressure is realized; compared with a two-step method of trapping and recompressing firstly in the prior art, the method has the advantages that the energy consumption of the electric compressor is reduced, only part of heat is consumed, low-grade heat is used for trapping carbon dioxide, and the carbon dioxide is in a higher pressure state in the regeneration tower so as to achieve liquefaction of the carbon dioxide.

The invention can also combine carbon dioxide liquefaction, integrate and add a refrigeration module, namely, realize refrigeration by utilizing the expansion and evaporation of liquid carbon dioxide, the carbon dioxide low-pressure gas generated by evaporation is mixed with the feed gas and returns to the absorption tower, thus completing the refrigeration cycle.

The invention can also incorporate carbon dioxide liquefaction, or incorporate refrigeration modules, integrated with the addition of power generation (power generation) modules. Under the condition of higher temperature of a heat source, the pressure of the carbon dioxide regenerated steam is increased, so that the carbon dioxide regenerated steam drives a gas turbine to output direct work or generate electricity; then, the carbon dioxide gas is liquefied and recovered, and the power generation cycle is completed. The efficient full-spectrum utilization of the heat source is realized.

The output work of the water turbine and the gas turbine can be partially and directly used for an internal solution pump or the whole power generation output.

The low pressure carbon dioxide gas mentioned above is all feed gas pressure, absorber pressure or slightly higher.

May be of multi-effect design, i.e. more than one absorption tower, more than one regeneration tower; the internal heat and mass transfer elements are in full countercurrent and are combined with an internal heat exchanger, so that the Exergy (for fire) loss is minimized; the energy efficiency is optimized.

Example (b): introducing a raw material gas containing carbon dioxide into an absorption tower, wherein an absorption liquid is arranged in the absorption tower, the absorption liquid absorbs the carbon dioxide in the raw material gas, in the process, the absorption liquid is circularly cooled by a primary cooling kettle to improve the absorption effect, the absorbed raw material gas is discharged through a purified gas exhaust pipe for subsequent treatment, the absorption liquid absorbing the carbon dioxide enters a regeneration tower, under the condition of continuously introducing a heat source, the pressure in the regeneration tower is increased to reach the critical pressure of the carbon dioxide, the absorption liquid decomposes the carbon dioxide after passing through a first heat exchange device and then enters a circulating pipe through a second liquid guide pipe, in the process, the second liquid guide pipe exchanges heat with the first liquid guide pipe through a GAX heat exchanger, the carbon dioxide generated in the regeneration tower is subjected to sulfur removal by a desulfurization device when passing through a third liquid guide pipe and then enters a secondary cooling kettle, and exchanges heat with a refrigerant in the secondary cooling kettle through the second heat exchange device, because the carbon dioxide is under the supercritical pressure, the carbon dioxide is liquefied after being subjected to heat exchange and temperature reduction by the refrigerant and then transferred to the liquid carbon dioxide storage tank.

The absorption liquid can be one or a plurality of alcohol-ammonia mixtures and ammonia water mixtures, the heat source introduced into the heat source inlet pipe can be one or a plurality of flue gas, steam, exhaust steam and CHP energy stations, the refrigerant can be low-temperature cooling water or a refrigerating unit for providing cooling water.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean 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 invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.