Method for desorbing carbon dioxide from an amine-rich liquid and rotating spray device

Abstract

The application provides a method for desorbing carbon dioxide in rich amine solution and a rotating spray device. The method comprises: dispersing the atomized rich amine solution into a rotating spray tower from top to bottom, and introducing hot hydrogen into the rotating spray tower from bottom to top at a cutting angle, the rich amine solution and the hot hydrogen form a cyclone in the rotating spray tower and counter-currently contact, the carbon dioxide in the rich amine solution is desorbed under the action of the heat carried by the hot hydrogen, and the desorbed carbon dioxide and hydrogen are discharged from the upper part of the rotating spray tower. In the method, the hot hydrogen is used to replace steam, the latent heat of the desorption process can be reduced by more than 10%, and the hydrogen and the carbon dioxide can also be used to prepare high-value products such as methanol or low-carbon hydrocarbons in the next process.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide recovery and utilization technology, specifically relating to a method for desorbing carbon dioxide from amine-rich liquid and a rotary spray device. Background Technology

[0002] The petrochemical industry accounts for approximately 13% of China's total carbon emissions and about 17% of the industrial sector's carbon emissions, ranking third in carbon intensity among industrial sectors. Under the dual carbon targets, the petrochemical industry faces significant pressure to reduce carbon emissions. The petrochemical industry is characterized by a long production and processing chain, diverse products, and significant differences in equipment, resulting in high total carbon emissions, numerous emission sources, varying degrees of concentration, and differentiated tail gas carbon dioxide emissions. Therefore, developing efficient carbon dioxide separation processes for the refining and chemical sectors is a crucial foundation for achieving carbon neutrality in the petrochemical industry.

[0003] Chemical amine capture is a technologically mature carbon capture technology and a major technical route for large-scale carbon capture in various industries under the current dual-carbon scenario. Desorption energy consumption accounts for 70% of the total energy consumption of the capture process, consisting of reaction heat, latent heat of vaporization, and sensible heat of temperature rise. Reaction heat accounts for 50-60% of desorption energy consumption, latent heat of vaporization for 30-40%, and sensible heat of temperature rise for 10%. High-value utilization of carbon dioxide is generally achieved through catalytic hydrogenation. Chemical amine capture followed by catalytic hydrogenation enables high-value utilization of carbon dioxide.

[0004] Carbon dioxide capture and conversion require different technological processes, resulting in complex workflows. Existing technologies, such as patents CN114191942 and CN115945054, utilize centrifugal reactors to rapidly desorb carbon dioxide from the absorbent in amine-rich solutions that have absorbed it. These technologies improve mass transfer efficiency by rotating the centrifugal reactor to break the absorbent into droplets, filaments, or films, but the residence time is limited and the desorption depth is insufficient. Patent CN101549274A discloses a rotating bed device for carbon dioxide capture and purification. In this method, during the desorption step, the rich solution from the absorption step is fed into the liquid inlet of the desorption rotating bed, where it comes into countercurrent contact with low-pressure water vapor from the gas inlet to complete the desorption process. However, this method does not further fix or utilize the desorbed carbon dioxide and has high energy consumption. Summary of the Invention

[0005] The purpose of this invention is to provide a method for desorbing carbon dioxide from a amine-rich solution.

[0006] Another object of the present invention is to provide a rotary spraying device.

[0007] To achieve the above objectives, the present invention provides a method for desorbing carbon dioxide from an amine-rich solution, comprising:

[0008] The atomized amine-rich liquid is dispersed from top to bottom into a rotary spray tower, and hot hydrogen gas is introduced into the rotary spray tower from bottom to top. The amine-rich liquid and hot hydrogen gas form a swirling flow and come into countercurrent contact in the rotary spray tower. The carbon dioxide in the amine-rich liquid is desorbed under the action of the heat carried by the hot hydrogen gas, and the desorbed carbon dioxide and hydrogen gas are discharged from the top of the rotary spray tower.

[0009] The method for desorbing carbon dioxide from a rich amine solution according to the present invention involves introducing hot hydrogen gas at a tangential angle into a rotary spray tower. The rich amine solution is a solution obtained after absorbing carbon dioxide with an amine absorbent.

[0010] In the method for desorbing carbon dioxide from amine-rich liquid according to the present invention, the gas-liquid ratio of hot hydrogen to amine-rich liquid is 60-90:1, preferably 80-90:1.

[0011] In the method for desorbing carbon dioxide from a amine-rich liquid according to the present invention, the temperature of the hot hydrogen gas is 100-110°C.

[0012] In the method for desorbing carbon dioxide from amine-rich liquid described in this invention, the partial pressure of hot hydrogen gas in the rotary spray tower is 0.2–0.3 MPa.

[0013] In the method for desorbing carbon dioxide from amine-rich liquid described in this invention, the residence time of hot hydrogen is 15–30 s.

[0014] The method for desorbing carbon dioxide from amine-rich liquid according to the present invention performs secondary distribution of hot hydrogen and atomized amine-rich liquid during the falling process.

[0015] To achieve the above objectives, the present invention also provides a rotary spray tower, comprising a tower body, a liquid inlet and a gas outlet on the upper part of the tower body, the liquid inlet being connected to a rotary spray atomizer, a gas inlet and a liquid outlet on the bottom of the tower body, a gas distributor located above the gas inlet inside the tower body, a secondary distributor located above the gas distributor, the secondary distributor comprising a rotating shaft, and rotating blades on the rotating shaft.

[0016] The rotary spray tower of the present invention includes a droplet distributor between the rotary spray atomizer and the secondary distributor. The use of the droplet distributor can reduce the occurrence of droplet adhesion to the wall.

[0017] The beneficial effects of this invention are as follows: This invention provides a method for desorbing carbon dioxide from amine-rich liquid using rotary spray. This method utilizes hot hydrogen instead of steam, which reduces the latent heat of desorption by more than 10%. Furthermore, the hydrogen and carbon dioxide can react in a subsequent process to prepare high-value products such as methanol or low-carbon hydrocarbons. This invention also provides an apparatus for desorbing carbon dioxide from amine-rich liquid using rotary spray. This apparatus is a rotary spray tower, in which the rotary spray atomizer rotates at high speed, ensuring uniform droplet dispersion and significantly increasing the gas-liquid contact area. Moreover, by establishing a secondary gas-liquid distributor within the tower, the gas-liquid mixing distribution within the tower is optimized, resulting in uniform gas-liquid distribution and more thorough mixing. Furthermore, the swirling gas-liquid mixture alleviates the phenomenon of wet material sticking to the walls, reducing scaling during operation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the rotating spray tower structure described in this invention;

[0019] Figure 2 This is a process flow diagram of the rotary spray desorption of carbon dioxide from amine-rich liquid to produce methanol according to the present invention;

[0020] Figure 3 This is a schematic diagram (top view) of a secondary distributor.

[0021] Figure 4 This is a schematic diagram (top view) of a droplet distributor.

[0022] In the attached figures, the following labels are used:

[0023] 1. Amine-rich liquid pump; 2. Valve; 3. Preheater; 4. Rotary spray atomizer; 5. Gas outlet; 6. Droplet distributor; 7. Secondary distributor; 8. Gas distributor; 9. Gas inlet; 10. Feed outlet; 11. Tower body; 12. Reactor. Detailed Implementation

[0024] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0025] Figure 1This is a schematic diagram of the structure of the rotary spray tower of the present invention, including a tower body 11. A liquid inlet and a gas outlet 5 are provided on the upper part of the tower body. The liquid inlet is connected to a rotary spray atomizer 4. A gas inlet 9 and a liquid outlet 10 are provided at the bottom of the tower body 11. A gas distributor 8 is provided inside the tower body 11 above the gas inlet 9. A secondary distributor 7 is provided above the gas distributor 8. The secondary distributor 7 includes a rotating shaft with rotating blades on it. Figure 3 As shown, the rotating shaft is rotatably fixed on the gas distributor, and the rotating blades rotate under the drive of the rotating shaft. A droplet distributor 6 is provided between the rotating spray atomizer and the secondary distributor. The structure of the droplet distributor 6 is as follows: Figure 4 As shown, there is a circular receiving device and a tubular liquid guiding device. The circular receiving device is provided with multiple partitions, which divide the circular receiving device into multiple receiving spaces. Each receiving space is provided with the tubular liquid guiding device. The circular receiving device is used to receive the droplets sprayed by the rotating spray atomizer 4, and then the droplets flow into the secondary distributor 7 for further dispersion through the tubular liquid guiding device.

[0026] Figure 2 This is a process flow diagram of the rotary spray desorption of carbon dioxide from a amine-rich liquid to produce methanol, as described in this invention. The amine-rich liquid, having absorbed carbon dioxide, enters the rotary spray atomizer 4 of the rotary spray tower via a amine-rich liquid pump, valves, and a preheater. The rotary spray atomizer 4 has multiple atomizing nozzles. The liquid is broken into fine droplets by the rotary spray atomizer 4 and sprayed out in a rotating manner. The droplets are evenly distributed and collected by a droplet distributor and fall into a secondary distributor 7. The secondary distributor 7 consists of two parts: a rotating shaft and rotating blades, as shown in the diagram. Figure 3 As shown, the high-speed rotation of the blades in the secondary distributor evenly distributes the hydrogen into the rotary spray tower. Hot hydrogen gas is introduced into the rotary spray tower at a tangential angle from the gas inlet 9 at the bottom, forming a vortex. After passing through the gas distributor, it can rotate and rise evenly, simultaneously providing power to the blades of the secondary distributor 7, causing them to spin. The falling amine-rich liquid droplets are also dispersed again under the action of the secondary distributor. The hot hydrogen gas flows upward and contacts the amine-rich liquid droplets. The heat carried by the hot hydrogen gas desorbs the carbon dioxide from the amine-rich liquid. The resulting lean amine liquid is discharged from the feed outlet 10. The desorbed carbon dioxide and hydrogen gas escape together from the gas outlet 5 and enter the reactor to react, ultimately producing methanol.

[0027] Example 1

[0028] use Figure 1The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device. The rotary spray atomizer in the device has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating rotary spray atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, hot hydrogen gas at a temperature of 108℃ is introduced at the bottom of the rotary spray tower. The gas-liquid ratio of hot hydrogen to amine solution is 80:1, the partial pressure of hot hydrogen is 0.2MPa, and the residence time of hot hydrogen is 15s. The hot hydrogen and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate in the solution reaches 88.56%, with a desorption energy consumption of 2.4GJ / tCO2.

[0029] Example 2

[0030] use Figure 1 The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device, which has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, hot hydrogen gas at 108℃ is introduced at the bottom of the rotary spray tower. The gas-liquid ratio of hot hydrogen to amine solution is 60:1, the partial pressure of hot hydrogen is 0.3MPa, and the residence time of hot hydrogen is 15s. The hot hydrogen and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate in the solution reaches 87.67%, with a desorption energy consumption of 2.2 GJ / t CO2.

[0031] Example 3

[0032] use Figure 1 The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device, which has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, hot hydrogen gas at 103℃ is introduced at the bottom of the rotary spray tower. The gas-liquid ratio of hot hydrogen to amine solution is 88:1, the partial pressure of hot hydrogen is 0.3MPa, and the residence time of hot hydrogen is 30s. The hot hydrogen and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate reaches 89.23%, with a desorption energy consumption of 2.3 GJ / t CO2.

[0033] Example 4

[0034] use Figure 1The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device, which has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, hot hydrogen gas at 108℃ is introduced at the bottom of the rotary spray tower. The gas-liquid ratio of hot hydrogen to amine solution is 85:1, the partial pressure of hot hydrogen is 0.25MPa, and the residence time of hot hydrogen is 20s. The hot hydrogen and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate in the solution reaches 88.37%, with a desorption energy consumption of 2.2 GJ / t CO2.

[0035] Example 5

[0036] use Figure 1 The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device, which has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, hot hydrogen gas at 108℃ is introduced at the bottom of the rotary spray tower. The gas-liquid ratio of hot hydrogen to amine solution is 75:1, the partial pressure of hot hydrogen is 0.2MPa, and the residence time of hot hydrogen is 20s. The hot hydrogen and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate in the solution reaches 86.89%, with a desorption energy consumption of 2.2 GJ / t CO2.

[0037] Comparative Example 1

[0038] Same as Example 1, except that hot hydrogen is replaced with hot steam at a temperature of 108°C.

[0039] use Figure 1 The rotary spray device shown is used for desorption. A 5wt% carbon dioxide-rich ethanolamine solution is introduced into the rotary spray device, which has 40 atomizing nozzles with a diameter of 5mm. Under the action of the high-speed rotating atomizer, the amine solution is dispersed in droplets within the rotary spray tower. Simultaneously, steam at 108℃ is introduced at the bottom of the rotary spray tower. The steam-to-amine solution gas-liquid ratio is 80:1, the steam partial pressure is 0.2MPa, and the steam residence time is 15s. The steam and amine solution are further dispersed and fully contacted by a secondary distributor to desorb carbon dioxide from the amine solution. The lean solution at the outlet is tested, and the carbon dioxide desorption rate reaches 88.15%, with a desorption energy consumption of 2.8 GJ / t CO2.

[0040] Comparative Example 2

[0041] An ethanolamine-rich liquid with a carbon dioxide content of 5 wt% was introduced into a centrifugal rotating bed, while hot hydrogen gas at a temperature of 108 °C was introduced simultaneously. The gas-liquid ratio of hot hydrogen gas to amine-rich liquid was 80:1, the partial pressure of hot hydrogen gas was 0.2 MPa, and the residence time of hot hydrogen gas was 15 s. The amine-rich liquid was desorbed using hot hydrogen gas, and the carbon dioxide desorption rate was 60.05%, with a desorption energy consumption of 2.2 GJ / tCO2.

[0042] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for desorbing carbon dioxide from an amine-rich solution, characterized in that, include: The atomized amine-rich liquid is dispersed from top to bottom into a rotary spray tower, and hot hydrogen gas is introduced into the rotary spray tower from bottom to top. The amine-rich liquid and hot hydrogen gas form a swirling flow and come into countercurrent contact in the rotary spray tower. The carbon dioxide in the amine-rich liquid is desorbed under the action of the heat carried by the hot hydrogen gas, and the desorbed carbon dioxide and hydrogen gas are discharged from the top of the rotary spray tower.

2. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The hot hydrogen gas is introduced into the rotating spray tower at a tangential angle.

3. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The amine-rich solution is a solution obtained after amine absorbents absorb carbon dioxide.

4. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The gas-liquid ratio of hot hydrogen to amine-rich liquid is 60~90:

1.

5. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The gas-liquid ratio of hot hydrogen to amine-rich liquid is 80-90:

1.

6. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The temperature of the hot hydrogen gas is 100~110℃.

7. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The partial pressure of hot hydrogen gas inside the rotary spray tower is 0.2~0.3 MPa.

8. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The residence time of hot hydrogen is 15~30s.

9. The method for desorbing carbon dioxide from a amine-rich solution according to claim 1, characterized in that, The hot hydrogen gas and the atomized amine-rich liquid during the descent process are distributed in a secondary manner.

Images