Patent Publication Number: US-2023134983-A1

Title: Processing system and processing method for blocked microreactor

Description:
TECHNICAL FIELD 
     The present invention relates to the technical field of reactor cleaning, and in particular to a processing system and a processing method for a blocked microreactor. 
     BACKGROUND 
     As an emerging research field in recent years, the microreactor technology began in the 1990s, has developed rapidly since the advent and has become a popular research direction. A microreactor has more efficient heat exchange performance, more concise continuous operation space and higher reaction rate. Therefore, the microreactor is mainly used in the fields of nanomaterial synthesis, green preparation of polymers and sample analysis. Compared with the nanomaterial prepared by the conventional method, a microchannel has the advantages of rapidness, simpleness, high purity, easy control, and accurate adjustment of nanoparticle size and morphology in the field of nanomaterial synthesis. 
     The microreactor has obvious advantages in the fields of nanomaterial preparation and chemical synthesis, but due to high accuracy and extremely small internal channels, generated high-viscosity substances or nanoparticles in a preparation process cannot effectively flow out and block a pipeline, so that the microreactor is not well accepted as a beneficial substitute for batch reactors, and the industrial application of the microreactor is greatly limited. In addition, the cost of the microreactor is high, and pipeline blockage may cause sudden rise of local pressure, thereby affecting the accuracy and even destroying the channels. 
     Patent CN104959093B discloses a method for eliminating the blockage of microreactor channel particles. The method must have specific requirements for the reactor structure. The cost of the reactor is high, and in a reaction process, ultrasound is used to prevent the blockage of microchannel, and formed nanoparticles may be influenced. 
     Patent CN100386277C discloses a method for eliminating blockage of a microchannel in a glass microfluidic chip. In the method, concentrated sulfuric acid and hydrogen peroxide are mixed, introduced into a channel, and heated until the solution is boiled, so that the blockage is dissolved through strong oxidizing property. The method has high energy consumption, is not conducive to safe production, and may cause waste of resources. After processing, the pipeline needs to be cleaned repeatedly and then used. 
     The above research alleviates the blockage of the microchannel to some extent, but due to the limitations of device cost and cleaning modes, it is difficult to popularize the method for cleaning the blockage of the microchannel. 
     SUMMARY 
     In view of the above problems in the prior art, the present invention provides a processing system and a processing method for a blocked microreactor. The present invention uses the effective reactivity of plasma and active free radicals in an excitation atmosphere to crack micro blockage in a micro channel in a short time. The method of the present invention has high flexibility and strong controllability, and can select different reaction atmospheres according to the type of the blockage and select plasma electrodes according to blocked regions to crack the blockage in a specific region; and the present invention is simple, easy to operate, safe and efficient, does not damage the internal structure of a processed microreactor, and can be used after simple washing. 
     The present invention has the following technical solution: 
     A processing system for a blocked microreactor is provided. The processing system comprises an air intake device, a flushing device, a microreactor to be processed and a plasma processing device; 
     One end of the microreactor to be processed is connected with the air intake device and the flushing device through a pipeline; 
     The other end of the microreactor to be processed is connected with a waste liquid bottle through the pipeline; 
     The microreactor to be processed is arranged between electrodes of the plasma processing device. 
     As the further improvement of the technical solution: 
     The microreactor to be processed is connected with the air intake device through the pipeline; a four-way valve is arranged between the microreactor to be processed and the air intake device; and three valves of the four-way valve are respectively connected with an air cylinder, an oxygen cylinder and an argon cylinder. 
     The air intake device is also provided with a mass flow control meter for regulating a gas flow; and the opening of the mass flow control meter is 20-50 sccm. 
     The flushing device comprises an injection pump and a syringe; and the syringe is respectively connected with a fourth valve of the four-way valve and the microreactor to be processed through a three-way valve. 
     The plasma processing device comprises electrodes, an AC power supply and an oscilloscope, and a quartz sheet is arranged between the electrodes and the microreactor to be processed. 
     The electrodes are stainless steel, copper, zinc or iron electrodes, and have the shapes of circular, square, triangular, rectangular or other irregular patterns, and processing area is 1-100 cm 2 ; and the quartz sheet has an edge larger than the edges of the electrodes by 1-2 cm, and a thickness of 1-3 mm. 
     The processing system also comprises a monitoring device, and the monitoring device comprises a camera and a display. 
     The display is a computer. 
     The material of the microreactor to be processed is glass, quartz, ceramic or borosilicate sand. 
     A method for processing a blocked microreactor by using the processing system is provided. The method comprises the following steps: 
     placing the microreactor to be processed between the electrodes of the plasma processing device, and placing a quartz sheet slightly larger than the electrodes on an upper side and a lower side of the microreactor to be processed respectively for dielectric barrier and microreactor protection; 
     opening the four-way valve, and adjusting the opening of the mass flow control meter, so that one or more mixed gases in the air cylinder, the oxygen cylinder and the argon cylinder enter the microreactor to be processed; 
     turning on the AC power supply; adjusting the oscilloscope; after the oscilloscope shows stably, collecting the output power of the AC power supply; wherein the output power applied by the AC power supply is 1.5-5 W and processing time is 3-10 min; 
     online observing the blockage situation in the microreactor to be processed in real time through the camera connected with the display, and turning off the AC power supply when the blockage is basically cracked; 
     starting the injection pump; controlling the output quantity of the injection pump, wherein an output flow is 0.1-2 mL/min, and time of circulation is 3-15 min; introducing cleaning liquid inside the syringe into the microreactor to be processed; collecting the cleaning liquid by the waste liquid bottle; and closing the four-way valve and the injection pump after the blockage in the pipeline is completely discharged. 
     The cleaning liquid is water, ethanol or acetone. 
     The present invention has the following beneficial technical effects: 
     The present invention uses the advantages of high technical activity, fast reaction, low temperature and no pollution of plasma to crack the internal blockage at normal pressure, low temperature, environmental friendliness, rapidness and controllability without damaging the microreactor and without the participation of strong acid and alkali reagents. 
     Because a cracking reaction can be completed at a microsecond level in the present invention, rapid cleaning of the blocked microreactor can be realized. The present invention has high flexibility, and the camera is connected with the computer, so that the changes of the blockage in the microreactor can be observed online in real time to achieve real-time control. 
     The reactor of the present invention is simple in structure, convenient in disassembly, small in occupation area, and low in reaction energy consumption, and does not need complex post-processing course after the reaction. In the reaction process, the reaction atmosphere can be changed by adjusting inlet gas, and the electrodes can be changed at any time according to the need of the blocked region, so that the operation is simple, flexible, efficient and safe and saves cost. In addition, because the electrodes can move freely on the microreactor flexibly to form partial discharge, the present invention can effectively treat the blocking problem, which cannot be solved by the traditional technique, inside the microreactor, such as dead corners. 
     The present invention not only cracks the blockage in the microreactor, but also degrades the residual deposition in the pipeline after the reaction, to further ensure that the microreactor is clean inside and can be used after simple washing. 
     The present invention can adjust the plasma atmosphere (such as argon, oxygen, hydrogen, vapor and air) for different types of blockages, and generate different active groups (such as O., H., N. and OH.) to react with the blockages, so as to more effectively crack the corresponding blockages. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic diagram of the present invention. 
       In the figure:  1  air cylinder;  2  oxygen cylinder;  3  argon cylinder;  4  mass flow control meter;  5  injection pump;  6  syringe; four-way valve;  8  three-way valve;  9  electrode;  10  quartz sheet;  11  microreactor to be processed;  12  AC power supply;  13  oscilloscope;  14  computer;  15  camera  16  waste liquid bottle. 
         FIG.  2    is a current-voltage diagram collected by an oscilloscope in embodiment 1. 
         FIG.  3    is a current-voltage diagram collected by an oscilloscope in embodiment 2. 
         FIG.  4    is a current-voltage diagram collected by an oscilloscope in embodiment 3. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will be specifically described below in combination with the drawings and the embodiments. 
     As shown in  FIG.  1   , a processing system for a blocked microreactor in the present embodiment comprises an air intake device, a flushing device, a microreactor to be processed and a plasma processing device. One end of the microreactor  11  to be processed is connected with the air intake device and the flushing device through a pipeline; the other end of the microreactor  11  to be processed is connected with a waste liquid bottle  16  through the pipeline; and the microreactor  11  to be processed is arranged between electrodes  9  of the plasma processing device. 
     The microreactor  11  to be processed is connected with the air intake device through the pipeline; a four-way valve  7  is arranged between the microreactor to be processed and the air intake device; and three valves of the four-way valve  7  are respectively connected with an air cylinder  1 , an oxygen cylinder  2  and an argon cylinder  3 . 
     The air intake device is also provided with a mass flow control meter  4  for regulating a gas flow; and the opening of the mass flow control meter  4  is 20-50 sccm. 
     The flushing device comprises an injection pump  5  and a syringe  6 ; and the syringe  6  is respectively connected with a fourth valve of the four-way valve  7  and the microreactor  11  to be processed through a three-way valve  8 . 
     The plasma processing device comprises electrodes  9 , an AC power supply  12  and an oscilloscope  13 , and a quartz sheet  10  is arranged between the electrodes  9  and the microreactor  11  to be processed. 
     The electrodes  9  are stainless steel, copper, zinc or iron electrodes, and have the shapes of circular, square, triangular, rectangular or other irregular patterns, and processing area is 1-100 cm 2 ; and the quartz sheet  10  has an edge larger than the edges of the electrodes  9  by 1-2 cm, and a thickness of 1-3 mm. 
     The processing system also comprises a monitoring device, and the monitoring device comprises a camera  15  and a display  14 . The display  14  is a computer. The material of the microreactor  11  to be processed is glass, quartz, ceramic or borosilicate sand. 
     A method for processing a blocked microreactor by using the processing system is provided. The method comprises the following steps: 
     1) placing the microreactor  11  to be processed between the electrodes  9  of the plasma processing device, and placing a quartz sheet  10  slightly larger than the electrodes  9  on an upper side and a lower side of the microreactor  11  to be processed respectively for dielectric barrier and microreactor protection; 
     2) opening the four-way valve  7 , and adjusting the opening of the mass flow control meter  4 , so that one or more mixed gases in the air cylinder  1 , the oxygen cylinder  2  and the argon cylinder  3  enter the microreactor  11 ; 
     3) turning on the AC power supply  12 ; adjusting the oscilloscope  13 ; after the oscilloscope  13  shows stably, collecting the output power of the AC power supply  12 , wherein the output power applied by the AC power supply  12  is 1.5-5 W and processing time is 3-10 min; 
     4) online observing the blockage situation in the microreactor  11  to be processed in real time through the camera  15  connected with the display  14 , and turning off the AC power supply  12  when the blockage is basically cracked; 
     5) starting the injection pump  5 ; controlling the output quantity of the injection pump  5 , wherein an output flow is 0.1-2 mL/min, and time of circulation is 3-15 min; introducing cleaning liquid inside the syringe  6  into the microreactor  11  to be processed; collecting the cleaning liquid by the waste liquid bottle  16 ; and closing the four-way valve  7  and the injection pump  5  after the blockage in the pipeline is completely discharged. 
     The cleaning liquid is water, ethanol or acetone. 
     Embodiment 1 
     A method for processing a blocked microreactor by using the processing system comprises the following steps: 
     1) placing the microreactor  11  to be processed between the electrodes  9  of the plasma processing device, and placing a quartz sheet  10  slightly larger than the electrodes  9  on an upper side and a lower side of the microreactor  11  to be processed respectively for dielectric barrier and microreactor protection; 
     2) opening the four-way valve  7 , and adjusting the opening of the mass flow control meter  4  to be 30 sccm, so that oxygen in the oxygen cylinder  2  enters the microreactor  11 ; 
     3) turning on the AC power supply  12 ; adjusting the oscilloscope  13 ; after the oscilloscope  13  shows stably, collecting the output power of the AC power supply  12 , wherein the output power applied by the AC power supply  12  is 2.09 W (as shown in  FIG.  2   . The output power can be obtained by integrating a region enclosed by the current-voltage diagram) and processing time is 8 min; 
     4) online observing the blockage situation in the microreactor  11  to be processed in real time through the camera  15  connected with the display  14 , and turning off the AC power supply  12  when the blockage is basically cracked; 
     5) starting the injection pump  5 ; controlling the output quantity of the injection pump  5 , wherein an output flow is 0.2 mL/min, and time of circulation is 10 min; introducing deionized water inside the syringe  6  into the microreactor  11  to be processed; collecting the waste deionized water by the waste liquid bottle  16 ; and closing the four-way valve  7  and the injection pump  5  after the blockage in the pipeline is completely discharged. 
     Embodiment 2 
     A method for processing a blocked microreactor by using the processing system comprises the following steps: 
     1) placing the microreactor  11  to be processed between the electrodes  9  of the plasma processing device, and placing a quartz sheet  10  slightly larger than the electrodes  9  on an upper side and a lower side of the microreactor  11  to be processed respectively for dielectric barrier and microreactor protection; 
     2) opening the four-way valve  7 , and adjusting the opening of the mass flow control meter  4  to be 25 sccm, so that oxygen in the oxygen cylinder  2  and argon in the argon cylinder  3  form mixed gas which enters the microreactor  11 ; 
     3) turning on the AC power supply  12 ; adjusting the oscilloscope  13 ; after the oscilloscope  13  shows stably, collecting the output power of the AC power supply  12 , wherein the output power applied by the AC power supply  12  is 1.73 W (as shown in  FIG.  3   . The output power can be obtained by integrating a region enclosed by the current-voltage diagram) and processing time is 10 min; 
     4) online observing the blockage situation in the microreactor  11  to be processed in real time through the camera  15  connected with the display  14 , and turning off the AC power supply  12  when the blockage is basically cracked; 
     5) starting the injection pump  5 ; controlling the output quantity of the injection pump  5 , wherein an output flow is 0.2 mL/min, and time of circulation is 10 min; introducing deionized water inside the syringe  6  into the microreactor  11  to be processed; collecting the waste deionized water by the waste liquid bottle  16 ; and closing the four-way valve  7  and the injection pump  5  after the blockage in the pipeline is completely discharged. 
     Embodiment 3 
     A method for processing a blocked microreactor by using the processing system comprises the following steps: 
     1) placing the microreactor  11  to be processed between the electrodes  9  of the plasma processing device, and placing a quartz sheet  10  slightly larger than the electrodes  9  on an upper side and a lower side of the microreactor  11  to be processed respectively for dielectric barrier and microreactor protection; 
     2) opening the four-way valve  7 , and adjusting the opening of the mass flow control meter  4  to be 50 sccm, so that air in the air cylinder  1  enters the microreactor  11 ; 
     3) turning on the AC power supply  12 ; adjusting the oscilloscope  13 ; after the oscilloscope  13  shows stably, collecting the output power of the AC power supply  12 , wherein the output power applied by the AC power supply  12  is 3.15 W (as shown in  FIG.  4   . The output power can be obtained by integrating a region enclosed by the current-voltage diagram) and processing time is 5 min; 
     4) online observing the blockage situation in the microreactor  11  to be processed in real time through the camera  15  connected with the display  14 , and turning off the AC power supply  12  when the blockage is basically cracked; 
     5) starting the injection pump  5 ; controlling the output quantity of the injection pump  5 , wherein an output flow is 1 mL/min, and time of circulation is 5 min; introducing deionized water inside the syringe  6  into the microreactor  11  to be processed; collecting the waste deionized water by the waste liquid bottle  16 ; and closing the four-way valve  7  and the injection pump  5  after the blockage in the pipeline is completely discharged.