Thermal management type methane reforming reactor combining active and passive control

Abstract

The invention discloses an active and passive control combined thermal management type methane reforming reactor which comprises a reactor shell and a stepping motor, the reactor shell and a sapphire window connected with the upper end of the reactor shell form a reaction cavity, and the reactor shell is filled with a porous medium; one side of the reactor shell and the bottom of the shell are respectively provided with a reaction gas inlet and a reaction gas outlet; a heat storage device shell is fixed to the outer side of the reactor shell, and a phase change heat storage material is installed in a closed cavity defined by the outer side of the reactor shell, the heat storage device shell and the sapphire window. A heat preservation layer is arranged on the outer side of the heat storage device shell in a surrounding mode. The stepping motor is used for driving the reactor to be close to or away from a solar radiation focus so as to adjust heat input. The phase change heat storage material is used for storing excess heat and performing heat compensation when the temperature is low, and the reactor is actively adjusted to be close to or away from a solar radiation focus to enable the surface energy flow of the reactor to tend to be stable, so that the problem that the methane dry reforming reaction is unstable is solved.

Description

Technical Field

[0001] The invention relates to a methane reforming reactor, in particular to a thermal management type methane reforming reactor combining active and passive control. Background Art

[0002] Both CH4 and CO2 are greenhouse gases. High-temperature reforming of CH4 and CO2 into CO and H2 can eliminate both greenhouse gases at the same time. The reforming reaction is as follows:

[0003]

[0004] This reforming reaction process consumes a lot of energy.

[0005] Solar energy is a renewable, abundant and clean green energy. Using it as an energy source to drive CH4-CO2 reforming by photothermal means has incomparable advantages. However, solar radiation is highly intermittent and volatile due to factors such as weather, cloud cover, and seasonal changes. The instability of solar radiation intensity directly leads to drastic temperature fluctuations in the solar-driven methane reforming reactor, which in turn affects the temperature control inside the reactor and the stability of the reaction. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a thermal management methane reforming reactor combining active and passive control to solve the problem of unstable methane dry reforming reaction caused by solar radiation fluctuations.

[0007] Technical solution: The present invention discloses a thermal management type methane reforming reactor combining active and passive control, comprising a reactor shell and a stepper motor. A sapphire window is connected to the upper end of the reactor shell for allowing light to enter the reactor. The sapphire window and the reactor shell constitute a reaction chamber. The interior of the reactor shell is filled with porous media. A reaction gas inlet is arranged on one side of the reactor shell, and a reaction gas outlet is arranged at the bottom of the reactor shell. A heat storage device shell is fixed to the outside of the reactor shell, and a phase change heat storage material is installed in a closed cavity surrounded by the outside of the reactor shell, the heat storage device shell and the sapphire window. An insulation layer is arranged around the outside of the heat storage device shell. The stepper motor is used to drive the reactor to approach or move away from the focus of solar radiation to adjust the heat input.

[0008] Furthermore, the thermal management type methane reforming reactor further comprises a gas-liquid separation device, and the reaction gas outlet is connected to the gas-liquid separation device.

[0009] Furthermore, the heat management type methane reforming reactor also includes a regenerator, which utilizes the high temperature gas generated by the reaction to heat the reaction gas, and the heated reaction gas is input into the reactor from the reaction gas inlet.

[0010] Furthermore, the thermal management type methane reforming reactor also includes a plurality of thermocouples for respectively monitoring the front surface temperature of the porous medium, the temperature of the phase change heat storage material, and the temperature of the reaction gas outlet.

[0011] Furthermore, the porous medium is composed of a metal porous foam and a catalyst, wherein the metal porous foam is made of copper, nickel and a high-temperature alloy containing these two elements by 3D printing, and the catalyst is Ni, Co, Si, Cu, Al, Ag or Rh.

[0012] Furthermore, the phase change heat storage material is one or more of carbonate, hydrochloride, chloride, lithium salt, and sulfate. When there are multiple types, it is a eutectic salt composed of any components.

[0013] Furthermore, the reactor shell and the heat storage device shell are cylindrical and made of high temperature resistant stainless steel.

[0014] Further, after the porous medium reaches a certain temperature, the reaction gas is introduced from the reaction gas inlet;

[0015] Under the condition of stable solar radiation, the reactor temperature and conversion rate are kept stable by adjusting the inlet reaction gas flow rate to change with the change of solar radiation;

[0016] When the radiation intensity increases, the reactor is controlled by a stepper motor to move away from the solar radiation focus and increase the reaction gas flow rate; when the radiation intensity decreases, the reactor is controlled by a stepper motor to move closer to the solar radiation focus and reduce the reaction gas flow rate, thereby ensuring the stable operation of the reactor.

[0017] Furthermore, when the direct normal radiation DNI is different, the distance between the reactor and the solar radiation focus and the incident energy satisfy different linear relationships.

[0018] Further, when DNI is 900, y=-23x+1900; when DNI is 600, y=-18x+1500; when DNI is 300, y=-15x+1200; x is the distance between the reactor and the focus of solar radiation, and y is the incident energy.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0020] (1) Active thermal management: The reaction process is optimized by actively adjusting the distance between the reactor and the solar radiation focus and controlling the gas flow rate. Different distances on the concentrator axis correspond to different light intensities. By actively adjusting the reactor to be close to or away from the solar radiation focus, the energy flow on the reactor surface can be stabilized under different radiation intensities, ensuring that the reaction process can be carried out efficiently and stably under various radiation conditions.

[0021] (2) Passive thermal management: Phase change thermal storage materials have the characteristics of high heat storage density and small temperature change, and can absorb / release a large amount of heat during the phase change process. Using phase change thermal storage materials to manage the heat of methane dry reforming reactions can improve the temperature stability in the reactor under radiation fluctuation conditions.

[0022] The present invention combines active and passive thermal management to accurately control the temperature fluctuation of the reactor, significantly improve the operating stability and thermal efficiency of the reactor, and effectively solve the problem of drastic temperature fluctuations caused by solar radiation fluctuations during the methane dry reforming reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of a thermal management type methane reforming reactor provided by an embodiment of the present invention;

[0024] Figure 2 yes Figure 1 Schematic diagram of the main structure of the reactor;

[0025] Figure 3 Schematic diagram of a methane reforming reactor experimental system in an embodiment of the present invention;

[0026] Figure 4 is a performance comparison chart of the present invention and the traditional reactor under radiation fluctuation conditions, wherein Figure 4 (a) is a comparison chart of methane conversion rate, Figure 4 (b) is a comparison chart of the average foam temperature;

[0027] Figure 5 is a graph showing the relationship between light intensity and DNI at different distances in an embodiment of the present invention, wherein Figure 5 (a) is the incident energy flux distribution diagram under different powers. Figure 5 (b) is the incident energy flux fitting diagram, Figure 5 (c) is the relationship between the distance between the reactor and the solar radiation focus and the incident energy at different powers. Figure 5 (d) is the radial distribution of the incident energy flux. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Attached Figures 1 to 5 The reference numerals in the figures are as follows:

[0030] 1. Sapphire window; 2. Reaction gas inlet; 3. Phase change heat storage material; 4. Heat storage device shell; 5. Reactor shell; 6. Insulation layer; 7. Porous medium; 8. Reaction gas outlet; 9. Gas-liquid separation device; 10. Thermocouple; 11. Stepper motor; 12. Regenerator.

[0031] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a thermal management type methane reforming reactor combining active and passive control, including a reactor shell 5, a gas-liquid separation device 9, a stepper motor 11, a regenerator 12 and three thermocouples 10.

[0032] The reactor shell 5 is cylindrical and made of high temperature resistant stainless steel. The upper end of the reactor shell 5 is connected with a sapphire window 1 for the concentrated light to enter the reactor. The sapphire window 1 and the reactor shell 5 form a reaction chamber. The reactor shell 5 is filled with a porous medium 7. A reaction gas inlet 2 is provided on the right side of the reactor shell 5, and a reaction gas outlet 8 is provided at the bottom of the reactor shell 5.

[0033] A heat storage device housing 4 is fixed to the outside of the reactor housing 5. The heat storage device housing 4 is also cylindrical and made of high-temperature resistant stainless steel. A phase-change heat storage material 3 is installed in the closed cavity surrounded by the outside of the reactor housing 5, the heat storage device housing 4 and the sapphire window 1. The phase-change heat storage material 3 can store and release heat. The heat storage device housing 4 is surrounded by a heat insulation layer 6, which can effectively reduce heat loss.

[0034] The reaction gas outlet 8 is rigidly connected to the gas-liquid separation device 9 through a PTFE tube, and the gas-liquid separation device 9 is fixed at the front end of the regenerator 12. The gas-liquid separation device 9 uses water-absorbing silica gel to absorb the water produced by the reaction to achieve the separation of gas phase and liquid phase products. The high-temperature gas produced by the reaction exchanges heat with the reaction gas in the regenerator 12, and the heated reaction gas is input into the reactor from the reaction gas inlet 2, thereby improving the overall thermal efficiency of the reactor.

[0035] The stepper motor 11 is fixed on the front support plate of the reactor housing 5. The stepper motor 11 is used to drive the reactor to approach or move away from the solar radiation focus to adjust the heat input. The three thermocouples 10 monitor the front surface temperature of the porous medium 7, the temperature of the phase change heat storage material 3, and the gas temperature of the reaction gas outlet 8 respectively.

[0036] The porous medium 7 is composed of a metal porous foam and a catalyst, wherein the metal porous foam is made of copper, nickel and a high-temperature alloy containing these two elements by 3D printing, and the catalyst is Ni, Co, Si, Cu, Al, Ag or Rh. In this embodiment, the length of the metal porous foam is L=0.03m, the porosity Φ=0.8, the pore diameter d=2.5mm, and the concave depth h=12mm.

[0037] The phase-change heat storage material 3 is one or more of carbonate, hydrochloride, chloride, lithium salt, and sulfate. When there are multiple types, it is a eutectic salt composed of any components.

[0038] Connect the methane reforming reactor described in the embodiment of the present invention to Figure 3In the experimental system shown (which is an existing experimental system), no reaction gas is introduced in the early stage of the reaction. Solar radiation passes through the sapphire window 1, the temperature of the porous medium 7 rises, and the phase change heat storage material 3 is heated by radial heat transfer. The phase change heat storage material 3 absorbs heat and rises in temperature. Part of the phase change heat storage material 3 undergoes a phase change process and stores energy in the form of latent heat.

[0039] After the porous medium 7 reaches a certain temperature, the reaction gas is introduced from the reaction gas inlet 2 .

[0040] The radiation intensity is obtained in real time through the DNI monitoring equipment. When the solar radiation is stable, the inlet reaction gas flow rate is adjusted (the gas flow rate is determined by Figure 3 The central control box shown in the figure is adjusted. The central control box has a built-in flow meter) which changes with the change of solar radiation to keep the reactor temperature and conversion rate stable.

[0041] When the radiation intensity increases, the reactor is controlled by the stepper motor 11 to move away from the solar radiation focus, and the reaction gas flow rate is increased to maintain the stable operation of the reactor.

[0042] When the radiation intensity weakens, the reactor is controlled by the stepper motor 11 to move closer to the solar radiation focus, while reducing the flow of reaction gas to ensure stable operation of the reactor.

[0043] Adjust the distance between the reactor and the focus of solar radiation to meet the Figure 5 (c) shows the empirical relationship to ensure that the reactor surface energy is maintained at a stable level of about 350W. When the DNI (direct normal radiation) is 900, the relationship between the energy and the axial distance is y = -23x + 1900; when the DNI is 600, the relationship between the energy and the axial distance is y = -18x + 1500; when the DNI is 300, the relationship between the energy and the axial distance is y = -15x + 1200. x is the axial distance (the distance between the front surface of the reactor and the xenon lamp, that is, the distance between the reactor and the focus of solar radiation), and y is the incident energy. Under different DNI conditions, by adjusting the distance between the reactor and the focus of solar radiation, the surface energy is kept in a stable area, thereby ensuring the stable operation of the reforming reactor.

[0044] Figure 4 The change of methane conversion rate over time under typical radiation fluctuation conditions is shown. The results show that the fluctuation of methane conversion rate is more obvious when heat storage is not configured. Specifically, when heat storage is not configured, the fluctuation range of methane conversion rate is 55.43% to 61.39%, and the average conversion rate is 58.5%. The reactor designed by the present invention has a methane conversion rate fluctuation range of 58.79% to 62.23%, a fluctuation range reduced by 2.52%, and an average conversion rate increased by 2 percentage points.

[0045] In summary, the present invention can significantly improve the efficiency and stability of solar thermochemical fuel production by combining passive thermal management of heat storage and heat release with active thermal management of controlling the reactor and the focal distance of solar radiation.

Claims

1. A thermal management type methane reforming reactor combining active and passive control, characterized in that: The invention comprises a reactor shell (5) and a stepper motor (11); the upper end of the reactor shell (5) is connected to a sapphire window (1) for allowing light to enter the reactor; the sapphire window (1) and the reactor shell (5) form a reaction chamber; the reactor shell (5) is filled with a porous medium (7); one side of the reactor shell (5) is provided with a reaction gas inlet (2); and the bottom of the reactor shell (5) is provided with a reaction gas outlet (8); a heat storage device shell (4) is fixed to the outside of the reactor shell (5); a phase change heat storage material (3) is installed in a closed chamber surrounded by the outside of the reactor shell (5), the heat storage device shell (4) and the sapphire window (1); and a heat insulation layer (6) is provided on the outside of the heat storage device shell (4); and the stepper motor (11) is used to drive the reactor to approach or move away from the focus of solar radiation to adjust the heat input.

2. The thermal management type methane reforming reactor according to claim 1, characterized in that: It also comprises a gas-liquid separation device (9), and the reaction gas outlet (8) is connected to the gas-liquid separation device (9).

3. The thermal management type methane reforming reactor according to claim 2, characterized in that: It also includes a regenerator (12), which utilizes the high-temperature gas generated by the reaction to heat the reaction gas, and the heated reaction gas is input into the reactor from the reaction gas inlet (2).

4. The thermal management type methane reforming reactor according to claim 1, characterized in that: It also includes a plurality of thermocouples (10) for respectively monitoring the front surface temperature of the porous medium (7), the temperature of the phase change heat storage material (3), and the gas temperature of the reaction gas outlet (8).

5. The thermal management type methane reforming reactor according to claim 1, characterized in that: The porous medium (7) is composed of a metal porous foam and a catalyst, wherein the metal porous foam is made of copper, nickel and a high-temperature alloy containing these two elements by 3D printing, and the catalyst is Ni, Co, Si, Cu, Al, Ag or Rh.

6. The thermal management type methane reforming reactor according to claim 1, characterized in that: The phase-change heat storage material (3) is one or more of carbonate, hydrochloride, chloride, lithium salt and sulfate. When there are more than one, it is a eutectic salt composed of any components.

7. The thermal management type methane reforming reactor according to claim 1, characterized in that: The reactor shell (5) and the heat storage device shell (4) are cylindrical and made of high-temperature resistant stainless steel.

8. The thermal management methane reforming reactor according to any one of claims 1 to 7, characterized in that: After the porous medium (7) reaches a certain temperature, the reaction gas is introduced from the reaction gas inlet (2); Under the condition of stable solar radiation, the reactor temperature and conversion rate are kept stable by adjusting the inlet reaction gas flow rate to change with the change of solar radiation; When the radiation intensity increases, the reactor is controlled by the stepper motor (11) to move away from the solar radiation focus, while increasing the reaction gas flow rate; when the radiation intensity decreases, the reactor is controlled by the stepper motor (11) to move closer to the solar radiation focus, while reducing the reaction gas flow rate; thereby ensuring stable operation of the reactor.

9. The thermal management type methane reforming reactor according to claim 8, characterized in that: When the direct normal radiation DNI is different, the distance between the reactor and the solar radiation focus and the incident energy satisfy different linear relationships.

10. The thermal management type methane reforming reactor according to claim 9, characterized in that: When DNI is 900, y=-23x+1900; when DNI is 600, y=-18x+1500; when DNI is 300, y=-15x+1200; x is the distance between the reactor and the focus of solar radiation, and y is the incident energy.

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