FOUR-AXIAL-FINS FIXED BED REACTOR FOR USE WITH CALCIUM ALUMINATE CARBONATES CO2 SORBENTS

Abstract

A four-axial-fins fixed bed reactor for use with calcium aluminate carbonates CO.sub.2 sorbents is provided. The four-axial-fins fixed bed reactor includes a tubular reactor and a four-axial-fins tube. The tubular reactor has a tubular reactor inner wall. The four-axial-fins tube is disposed in the tubular reactor, wherein the four-axial-fins tube includes a tube and four axial fins. The tube has a tube outer wall. An annular space is formed between the tube and the tubular reactor. The four axial fins extend along the radial direction of the tubular reactor from the tube outer wall to connect the tubular reactor inner wall, wherein the annular space is equally divided by the four axial fins.

Claims

1. A four-axial-fins fixed bed reactor for use with calcium aluminate carbonates CO.sub.2 sorbents, comprising: a tubular reactor having a tubular reactor inner wall; and a four-axial-fins tube disposed in the tubular reactor, including: a tube having a tube outer wall, wherein an annular space is formed between the tube and the tubular reactor; four axial fins extending along the radial direction of the tubular reactor from the tube outer wall to connect the tubular reactor inner wall, wherein the annular space is equally divided by the four axial fins.

2. A fixed bed reactor, comprising: a tubular reactor having a tubular reactor inner wall; and a heat conducting device disposed in the tubular reactor, wherein the heat conducting device is removable from the tubular reactor, wherein the heat conducting device includes a plurality of heat conducting plates disposed along the axial direction of the tubular reactor and connected to each other, wherein the plurality of heat conducting plates extend outward along the radial direction of the tubular reactor from the interior of the tubular reactor to contact the tubular reactor inner wall.

3. The fixed bed reactor of claim 2, wherein the fixed bed reactor is for a first material to adsorb a second material and to desorb the same after being heated.

4. The fixed bed reactor of claim 3, wherein the first material is calcium aluminate carbonates CO.sub.2 sorbents and the second material is CO.sub.2.

5. The fixed bed reactor of claim 2, wherein the cross section of the heat conducting device perpendicular to the axial direction of the tubular reactor presents a cross shape.

6. The fixed bed reactor of claim 2, wherein the heat conducting device further includes an inner tube disposed in the center of the tubular reactor along the axial direction of the tubular reactor, wherein the inner tube has an inner tube outer wall, wherein one of two opposite side edges of each heat conducting plate contacts the tubular reactor inner wall and the other of the two opposite side edges connects the inner tube outer wall.

7. The fixed bed reactor of claim 6, wherein there are four heat conducting plates, wherein there is a 90 degrees angle between the adjacent heat conducting plates.

8. The fixed bed reactor of claim 6, wherein the inner radius of the tubular reactor is 50.8 mm, wherein the inner radius and the thickness of the inner tube are respectively 18.5 mm and 4 mm, wherein the thickness of the plurality of heat conducting plates is 4 mm, wherein the length of the tubular reactor, the length of the inner tube, and the length of the plurality of heat conducting plates are 500 mm.

9. The fixed bed reactor of claim 6, wherein the radius of the tubular reactor is in the range of 2.14 to 4.75 times the radius of the inner tube.

10. The fixed bed reactor of claim 6, wherein an annular space is formed between the inner tube and the tubular reactor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a schematic perspective view of a conventional tube reactor;

[0025] FIG. 2A is a cross sectional view according to one embodiment of the present invention;

[0026] FIG. 2B is a schematic view according to one embodiment of the present invention;

[0027] FIG. 2C is an exploded view according to one embodiment of the present invention;

[0028] FIGS. 3A and 3B are cross sectional views according to different embodiments of the present invention;

[0029] FIGS. 4A and 4B are perspective views according to one embodiment of the present invention further including an inner tube;

[0030] FIG. 5 is a perspective view according to the preferred embodiment of the present invention;

[0031] FIG. 6 is a flow chart of performing a simulation according to one embodiment of the present invention;

[0032] FIG. 7 is a schematic view showing the dimension of components of the present invention;

[0033] FIG. 8 is a schematic view showing the simulation result of radial temperature distribution of the present invention;

[0034] FIG. 9 is a schematic view showing the simulation result of desorption of the present invention and the prior art at different temperatures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] As the embodiment shown in FIGS. 2A to 2C, the fixed bed reactor 900 of the present invention includes a tubular reactor 100 and a heat conducting device 300. The tubular reactor 100 has a tubular reactor inner wall 110. As shown in FIG. 2C, the heat conducting device 300 is disposed in the tubular reactor 100 and is removable from the tubular reactor 100. The heat conducting device 300 includes a plurality of heat conducting plates 310 disposed along the axial direction 210 of the tubular reactor 100 and connected to each other. The plurality of heat conducting plates 310 extend outward along the radial direction of the tubular reactor 100 from the interior of the tubular reactor 100 to contact the tubular reactor inner wall 110. More particularly, the heat conducting device 300 has a size that makes heat conducting plates 310 engage the tubular reactor inner wall 110. In other words, the heat conducting plates 300 fit closely with the tubular reactor 100. In different embodiments, however, for the convenience of fixing and operation, grooves can be disposed on the tubular reactor inner wall 110 for the heat conducting plates 310 to be inserted therein.

[0036] As the embodiment shown in FIGS. 2A to 2C, taking a different point of view, the fixed bed reactor 900 includes a tubular reactor 100 and a heat conducting device 300. The tubular reactor 100 has a tubular reactor inner wall 110. The tubular reactor 100 preferably presents cylinder shape, but not limited thereto. The heat conducting device 300 is disposed in the tubular reactor 100 and is removable from the tubular reactor 100. The heat conducting device 300 includes a plurality of heat conducting plates 310 disposed along the axial direction 210 of the tubular reactor 100 and connected to each other. The plurality of heat conducting plates 310 extend along the radial direction of the tubular reactor 100 from the tubular reactor inner wall 110 toward the interior of the tubular reactor 100.

[0037] Since the heat conducting plates 310 of the heat conducting device 300 connect the tubular reactor inner wall 110, the heat conducting device 300 helps to transfer the heat received by the tubular reactor 100 to the interior of the tubular reactor 100. Thus, the heat conduction efficiency and temperature uniformity are increased to improve the reaction efficiency of the reactants in the tubular reactor 100. On the other hand, because the heat conducting device 300 is removably disposed in the tubular reactor 100, the heat conducting device 300 can be removed from the tubular reactor 100 after the fixed bed reactor 900 is used. Hence, it is convenient to change the reactants in the tubular reactor 100. More particularly, after the heat conducting device 300 is removed from the tubular reactor 100, both the heat conducting device 300 and the tubular reactor 100 are more easily to be cleaned to remove reaction waste. This ensures a complete filling of fresh reactants after reassembling the fixed bed reactor 900. In the preferred embodiment, the heat conducting device 300 is made of copper. In different embodiments, however, the heat conducting device 300 can be made of other materials having good heat conductance.

[0038] In one embodiment, the fixed bed reactor 900 is for a first material to adsorb a second material and to desorb the same after being heated. More particularly, the first material is calcium aluminate carbonates CO.sub.2 sorbents and the second material is CO.sub.2. Since the CO.sub.2 adsorption/desorption efficiency of calcium aluminate carbonates CO.sub.2 sorbents is greatly influenced by temperature, good heat conduction efficiency and temperature uniformity in the tubular reactor 100 can improve the CO.sub.2 adsorption/desorption efficiency of calcium aluminate carbonates CO.sub.2 sorbents.

[0039] As the embodiment shown in FIGS. 2A to 2C, the cross section of the heat conducting device 300 perpendicular to the axial direction 210 of the tubular reactor 100 presents a cross shape. More particularly, in this embodiment, the fixed bed reactor 900 includes four heat conducting plates 310, wherein there is a 90 degrees angle between the adjacent heat conducting plates 310. In different embodiments, however, the heat conducting device 300 can present different shapes, wherein the angel between the adjacent heat conducting plates 310 can be other than 90. As the embodiment shown in FIG. 3A, the cross section of the heat conducting device 300 perpendicular to the axial direction of the tubular reactor 100 presents a three-pointed-star shape, wherein the heat conducting device 300 has fewer heat conducting plates 310 to decrease the material and manufacturing cost. As the embodiment shown in FIG. 3B, the cross section of the heat conducting device 300 perpendicular to the axial direction of the tubular reactor 100 presents an eight-pointed-star shape, wherein the heat conducting device 300 has more heat conducting plates 310 to further improve the heat conduction efficiency and temperature uniformity in the tubular reactor 100.

[0040] As a different embodiment shown in FIG. 4A, the heat conducting device 300 further includes an inner tube 330 disposed in the center of the tubular reactor 100 along the axial direction 210 of the tubular reactor 100. An annular space is formed between the inner tube 330 and the tubular reactor 100. The inner tube 330 has an inner tube outer wall 331, wherein a side edge 311 of the heat conducting plate 310 contacts the tubular reactor inner wall 110 and a side edge 313 of the heat conducting plate 310 contacts the inner tube outer wall 331. More particularly, as the embodiment shown in FIG. 4B, the heat conducting plate 310 is preferably welded on the inner tube outer wall 331 with the side edge 311. In different embodiments, however, the heat conducting plate 310 can be fixed on the inner tube outer wall 331 by screwing, engaging, etc.

[0041] With the inner tube 330, the mechanical strength of the heat conducting device 300 is increased, wherein the deformation of the heat conducting plate 310 is decreased. Accordingly, it prevents the heat conducting device 300 from deforming when being removed from the tubular reactor 100. Besides, the inner tube 330 further improves the heat conduction efficiency and temperature uniformity in the tubular reactor 100.

[0042] Taking a different point of view, as the embodiment shown in FIG. 5, the fixed bed reactor 900 of the present invention is a four-axial-fins fixed bed reactor for use with calcium aluminate carbonates CO.sub.2 sorbents, which includes a tubular reactor 100 and a four-axial-fins tube 300. The tubular reactor 100 has a tubular reactor inner wall 110. The four-axial-fins tube 300 is disposed in the tubular reactor 100, wherein the four-axial-fins tube 300 includes a tube 330 and four axial fins 310. The tube 330 has a tube outer wall 331, wherein an annular space 400 is formed between the tube 330 and the tubular reactor 100. The four axial fins 310 extend along the radial direction of the tubular reactor 100 from the tube outer wall 331 to connect the tubular reactor inner wall 110, wherein the annular space 400 is equally divided by the four axial fins 310. Thus, the heat conduction is more uniform.

[0043] To confirm the usefulness of the present invention, a computer simulation is performed.

[0044] The software to perform the simulation is COMSOL 5.0 (COMSOL INC., USA), which calculates with Finite Element Method. The flow chart of performing the simulation is shown in FIG. 6. As shown in FIG. 7, the inner radius R.sub.o of the tubular reactor 100 is 50.8 mm; the inner radius R.sub.i and the thickness W of the inner tube are respectively 18.5 mm and 4 mm; the thickness t of each heat conducting plate is 4 mm. Preferably, the radius of the tubular reactor is in the range of 2.14 to 4.75 times the radius of the inner tube. As shown in FIG. 4A, the length of the tubular reactor, the length of the inner tube, and the length of the plurality of heat conducting plates are 500 mm. At first, a geometric model is built up. Different physical models (free and porous medium flow, porous medium heat conductance) must be coupled in the simulation process. Fundamental parameters (basic thermodynamic properties, chemical reaction rate, etc.) and boundary and initial conditions (temperature, pressure, gas velocity, etc.) are set up then. Suitable grids and convergence standard are built up to obtain a solution.

[0045] The Governing equations of the mass, momentum, and energy of the fluid in the reactor are respectively:

[00001]$\begin{array}{cc}.Math.\left(.Math..Math.V\right)=0& \left(1\right)\\ \frac{1}{{\mathrm{.Math.}}^2}.Math..Math.\left(.Math..Math.\mathrm{VV}\right)=.Math.\left[-\mathrm{pI}+\frac{}{\mathrm{.Math.}}.Math.\left(.Math.V+{\left(V\right)}^T\right)-\frac{2.Math..Math.}{3.Math..Math.s}.Math.I.Math..Math..Math.V\right]-\frac{}{k_{\mathrm{br}}}.Math.V& \left(2\right)\\ .Math.\mathrm{.Math.}.Math..Math..Math.\left(.Math..Math.C_p.Math.\mathrm{VT}\right)=.Math.\left({}_s.Math.T\right)+Q& \left(3\right)\end{array}$

wherein V is velocity vector (u, v, w); is fluid density; is porosity; is viscosity; p is pressure; C.sub.p is specific heat capacity; T is temperature; Q is energy source term resulted by chemical reaction; .sub.e is effective thermal conductivity; k.sub.br is penetration rate.

[0046] The boundary conditions of the Governing equations are:

(1) The Inlet of the Reactor

[0047]
u=u.sub.in,T=T.sub.in(4)

(2) The Outlet of the Reactor

[0048] [00002]$\begin{array}{cc}\frac{V}{Z}=\frac{T}{Z}=0,p=p_{\mathrm{out}}& \left(5\right)\end{array}$

(3) The Solid Side Walls of the Inlet and Outlet of the Reactor

[0049]
T=0(6)

[0050] The side walls are assumed adiabatic.

(4) The Interface Between the Gas and the Solid Wall

[0051] [00003]$\begin{array}{cc}V=0,{}_e.Math.\frac{T}{r}={}_c.Math.\frac{T_c}{r}& \left(7\right)\end{array}$

[0052] On the interface, No-slip condition is appointed, wherein .sub.c and T.sub.c in the equations are respectively thermal conductivity and temperature of the solid wall.

(5) Heating Wall

[0053] [00004]$\begin{array}{cc}V=0,T=T_c,{}_e.Math.\frac{T}{r}={}_c.Math.\frac{T_c}{r}& \left(8\right)\end{array}$

[0054] In the present invention, the size of the internal tube can be adjusted. Under the above described desorption conditions, radial temperature distribution simulation on the central cross section of the fixed bed reactor are performed with different sizes of internal tubes, wherein the simulation results are shown in FIG. 8. As shown in FIG. 8, when desorption temperature is 850 C., the preferred inner radius R.sub.i of the inner tube is 18.5 mm, which has the smallest temperature difference with respect to the setting desorption temperature, i.e. 68 C. (=850 C.782 C.). The maximum temperature difference is lowed about 45.4% (=68 C./(850 C.700 C.)*100%). The average temperature in the tube is raised from 758 C. to 809 C. The non-uniform temperature distribution is effectively improved to enhance the adsorption/desorption efficiency of the CO.sub.2 sorbents.

[0055] On the other hand, FIG. 9 illustrates the simulation results of desorption time (based on 90%) of prior art, the present invention with four-axial-fins but without inner tube, and the present invention with both four-axial-fins and inner tube at desorption temperatures of 850 C., 900 C., and 950 C. As shown in FIG. 9, taking 90% CO.sub.2 desorption as the base, compared with prior art, the desorption time of the reactor in the present invention having inner tube and fins at desorption temperatures of 850 C., 900 C., and 950 C. are decreased respectively by 39%, 44%, and 53%. Moreover, regarding desorption time, that of the prior art is longer than that of the fixed bed reactor of the present invention with four-axial-fins but without inner tube, and further longer than that of the fixed bed reactor of the present invention with both four-axial-fins and inner tube (R.sub.i is 18.5 mm). Accordingly, regarding the desorption efficiency, that of the present invention with both four-axial-fins and inner tube (R.sub.i is 18.5 mm) is better than that of the fixed bed reactor of the present invention with four-axial-fins but without inner tube, and further better than that of the prior art.

[0056] Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.