Supercritical autoclave and method for improving foaming ratio stability

Abstract

The invention relates to a supercritical autoclave and a method for improving foaming ratio stability thereof, the supercritical autoclave comprises an autoclave body and a driving device, the right end of the autoclave body is provided with an opening, an end cover is assembled at the opening, a stirring paddle penetrates through the end cover, the driving device is connected with the stirring paddle, and the supercritical autoclave further comprises a gas detection module and a gas supplement module, the gas detection module is formed by sequentially connecting a high-pressure throttle valve, a back pressure valve and a carbon dioxide monitor in series, and the high-pressure throttle valve is communicated with the kettle body; the gas supplementing module comprises a carbon dioxide supplementing unit and a liquid nitrogen supplementing unit. Through the combination of the throttle valve and the back pressure valve, the gas flow and pressure are accurately controlled, and the detection accuracy is ensured; the gas concentration is constant through closed-loop control, the foaming ratio difference between batches is reduced to be within + / -2%, and the stability is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of supercritical foaming, and particularly to a supercritical autoclave and a method for improving the stability of foaming ratio. Background Art

[0002] In the process of supercritical autoclave pressure foaming, an autoclave is usually used as a container for impregnating supercritical fluid. After the material enters the autoclave, nitrogen or carbon dioxide or a mixture of both is introduced, and high temperature and high pressure are maintained until an equilibrium state is reached. However, the prior art has the following problems:

[0003] Inconsistent foaming ratio: Since the amount of material affects the absorption level of carbon dioxide, more carbon dioxide is absorbed when there is more material, and less carbon dioxide is absorbed when there is less material, resulting in a large deviation in the equilibrium concentration at the end of adsorption, and further leading to inconsistent foaming ratios.

[0004] Equilibrium concentration difference: In the process of supercritical autoclave pressure foaming, the absorption rates of different gases are different, resulting in the equilibrium concentration of the system after absorption saturation no longer being the initial concentration. Between batches, due to different quantities and qualities of the materials, the absorption amount will also change, resulting in differences in the equilibrium concentration of each batch. Summary of the Invention

[0005] The present invention provides a supercritical autoclave and a method for improving the stability of foaming ratio, so as to overcome the problem that between batches of existing supercritical autoclaves, due to different quantities and qualities of the small soles embryos, the absorption amount will also change, thus resulting in differences in the equilibrium concentration of each batch and different foaming ratios.

[0006] The present invention adopts the following technical solutions:

[0007] A supercritical foaming autoclave includes a kettle body and a driving device. The right end of the kettle body is provided with an opening, and an end cover is assembled at this opening. A stirring paddle is arranged through the end cover, and the driving device is connected to the stirring paddle. It also includes a gas detection module and a gas supplement module. The gas detection module is composed of a high-pressure throttle valve, a back-pressure valve, and a carbon dioxide monitor connected in series in sequence. The high-pressure throttle valve is connected to the above-mentioned kettle body; the gas supplement module includes a carbon dioxide supplement unit and a liquid nitrogen supplement unit, and the carbon dioxide supplement unit and the liquid nitrogen supplement unit are connected to the kettle body.

[0008] Further, it also includes a PLC controller. The PLC controller is connected to the above-mentioned carbon dioxide monitor, the above-mentioned carbon dioxide supplement unit, and the above-mentioned liquid nitrogen supplement unit. The PLC controller controls the start and stop of the carbon dioxide supplement unit and the liquid nitrogen supplement unit according to the signal of the monitor.

[0009] Further, the above-mentioned driving device is a magnetic stirrer.

[0010] Furthermore, the above carbon dioxide monitor is provided with a fluid connector.

[0011] A method for improving the stability of the foaming ratio of a supercritical autoclave, comprising the following steps:

[0012] Step 1: Add the material into the above autoclave, introduce nitrogen and / or carbon dioxide gas into the autoclave, heat the autoclave, and maintain high temperature and high pressure until reaching an equilibrium state;

[0013] Step 2: Open the high-pressure throttle valve and the back-pressure valve, and detect the carbon dioxide concentration in the reaction kettle in real time;

[0014] Step 3: The PLC controller controls the start and stop of the carbon dioxide supplement unit and / or the liquid nitrogen supplement unit according to the monitor signal, and dynamically supplements carbon dioxide or nitrogen according to the concentration deviation to keep the concentration constant;

[0015] Step 4: After the material is saturated with absorption, relieve the pressure to foam.

[0016] Furthermore, the detection of the above carbon dioxide concentration is realized through the high-pressure throttle valve, the back-pressure valve and the flow-through carbon dioxide detector, and the inlet pressure of the detector is stabilized at 0.1 MPa.

[0017] Furthermore, the high-pressure throttle valve controls the flow rate of the detected gas to be 1-10 mL / min, and the trigger threshold of the supplement unit is a concentration deviation of ±1%.

[0018] From the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention realizes a constant gas concentration through closed-loop control, reduces the difference in the foaming ratio between batches to within ±2%, and significantly improves the stability.

[0020] 2. The present invention accurately controls the gas flow rate and pressure through the combination of the throttle valve and the back-pressure valve to ensure the accuracy of detection.

[0021] 3. The influence of the loss of trace gas (<0.5%) in the present invention on the pressure in the autoclave can be ignored, ensuring the stability of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the supercritical autoclave of the present invention.

[0023] Figure 2 It is a schematic structural diagram of the connection between the PLC controller of the present invention and all components. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following describes the specific embodiments of the present invention with reference to the drawings.

[0025] Refer toFigure 1 , a supercritical foaming autoclave, comprising an autoclave body 1 and a driving device 12. A feeding port is provided at the left end of the autoclave body, and a cover plate is provided at the feeding port. An opening is provided at the right end of the autoclave body 1, and an end cover 11 is assembled at the opening. A stirring paddle is arranged through the end cover 11, and the driving device 12 is connected to the stirring paddle. It also includes a gas detection module 2 and a gas replenishment module 3. The gas detection module 2 is composed of a high-pressure throttle valve 21, a back pressure valve 22, and a carbon dioxide monitor 23 connected in series in sequence. The high-pressure throttle valve 21 is communicated with the above autoclave body 1; the gas replenishment module 3 includes a carbon dioxide replenishment unit 31 and a liquid nitrogen replenishment unit 32. The carbon dioxide replenishment unit 31 and the liquid nitrogen replenishment unit 32 are communicated with the autoclave body 1. The carbon dioxide replenishment unit 31 includes a liquid carbon dioxide storage tank, a cryogenic pressure pump, a gasification skid, and an electromagnetic control switch. The electromagnetic control switch controls the carbon dioxide gas to be introduced into the reaction autoclave body 11. The liquid nitrogen replenishment unit 32 includes a liquid nitrogen storage tank, a cryogenic pressure pump, a gasification skid, and an electromagnetic control switch. The electromagnetic control switch controls the nitrogen gas to be introduced into the reaction autoclave body 11.

[0026] Refer to Figure 2 , it also includes a PLC controller. The PLC controller is connected to the above carbon dioxide monitor 23, the above carbon dioxide replenishment unit 31, and the above liquid nitrogen replenishment unit 32. The PLC controller controls the start and stop of the carbon dioxide replenishment unit 31 and the liquid nitrogen replenishment unit 32 according to the monitor signal.

[0027] The above driving device 12 is a magnetic stirrer.

[0028] The above carbon dioxide monitor 23 is provided with a fluid joint.

[0029] A method for improving the stability of the foaming ratio of a supercritical autoclave includes the following steps:

[0030] Step 1, add the material into the above autoclave, introduce nitrogen and / or carbon dioxide gas into the autoclave, heat the autoclave, and maintain high temperature and high pressure until reaching an equilibrium state;

[0031] Step 2, open the high-pressure throttle valve 21 and the back pressure valve 22, and detect the carbon dioxide concentration in the reaction autoclave in real time;

[0032] Step 3, the PLC controller controls the start and stop of the carbon dioxide replenishment unit 31 and / or the liquid nitrogen replenishment unit 32 according to the monitor signal, dynamically replenish carbon dioxide or nitrogen according to the concentration deviation, and keep the concentration constant;

[0033] Step 4, after the material is saturated with absorption, release the pressure for foaming.

[0034] The detection of the above carbon dioxide concentration is realized through the high-pressure throttle valve 21, the back pressure valve 22, and a flow-through carbon dioxide detector, and the inlet pressure of the detector is stable at 0.1 MPa.

[0035] The flow rate of the detection gas controlled by the above high-pressure throttle valve is 1-10 mL / min, and the triggering threshold of the replenishment unit is a concentration deviation of ±1%.

[0036] Since the inlet pressure of the carbon dioxide detector is about 0.1 Mpa, it is necessary to lead out the high-pressure fluid in the kettle through an appropriate path and decompress it into atmospheric pressure gas, including a high-pressure throttle valve 21 + a back pressure valve 22 + a carbon dioxide detector with a fluid connector. The high-pressure pressure reducing valve is used to control the flow rate, and the flow rate is controlled at 1-10 ml / min. The back pressure valve 22 is used to control the air pressure at the inlet of the detector. The outlet of the detector is connected to the atmosphere. During the whole production process, the gas always remains in a flowing state, and the influence of the loss of these trace gases on the pressure in the reaction kettle is negligible.

[0037] The above is only the specific implementation mode of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantive modification of the present invention using this concept shall fall within the scope of infringement of the protection scope of the present invention.

Claims

1. A supercritical foaming autoclave, comprising an autoclave body and a driving device. The right end of the autoclave body is provided with an opening, and an end cover is assembled at this opening. A stirring paddle is disposed through the end cover, and the driving device is connected to the stirring paddle. It is characterized in that: It further includes a gas detection module and a gas replenishment module. The gas detection module is composed of a high-pressure throttle valve, a back pressure valve, and a carbon dioxide monitor connected in series in sequence. The high-pressure throttle valve is connected to the autoclave body; the gas replenishment module includes a carbon dioxide replenishment unit and a liquid nitrogen replenishment unit, and the carbon dioxide replenishment unit and the liquid nitrogen replenishment unit are connected to the autoclave body.

2. The supercritical foaming autoclave according to claim 1, wherein: It further includes a PLC controller. The PLC controller is connected to the carbon dioxide monitor, the carbon dioxide replenishment unit, and the liquid nitrogen replenishment unit. The PLC controller controls the start and stop of the carbon dioxide replenishment unit and the liquid nitrogen replenishment unit according to the monitor signal.

3. The supercritical foaming autoclave according to claim 1, characterized in that: The driving device is a magnetic stirrer.

4. The supercritical foaming autoclave according to claim 1, wherein: The carbon dioxide monitor is provided with a fluid connector.

5. A method for improving the stability of the foaming ratio of a supercritical autoclave, characterized in that It includes the following steps: Step 1: Add the material into the autoclave as described in claims 1-4, introduce nitrogen and / or carbon dioxide gas into the autoclave, heat the autoclave, and maintain high temperature and high pressure until reaching an equilibrium state. Step 2: Open the high-pressure throttle valve and the back pressure valve, and detect the carbon dioxide concentration in the reaction kettle in real time. Step 3: The PLC controller controls the start and stop of the carbon dioxide replenishment unit and / or the liquid nitrogen replenishment unit according to the monitor signal, and dynamically replenishes carbon dioxide or nitrogen according to the concentration deviation to keep the concentration constant. Step 4: After the material is saturated with absorption, release the pressure to foam.

6. A method for improving the stability of the foaming ratio of a supercritical autoclave as described in claim 5, characterized in that; The detection of the carbon dioxide concentration is realized through the high-pressure throttle valve, the back pressure valve, and a flow-through carbon dioxide detector, and the inlet pressure of the detector is stabilized at 0.1 MPa.

7. A method for improving the stability of the foaming ratio of a supercritical autoclave according to claim 5, characterized in that: The high-pressure throttle valve controls the flow rate of the detected gas to be 1-10 mL / min, and the trigger threshold of the replenishment unit is a concentration deviation of ±1%.

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