3D printing nozzle and printing method for printing barrier of polluted site

Abstract

The invention belongs to the field of 3D printing nozzles, and discloses a 3D printing nozzle for printing a polluted site barrier and a printing method, which can realize synchronous rapid carbonization and printing construction of a printing material, form a composite barrier with a relatively high sealing effect, and remarkably improve the emergency disposal efficiency of an emergent site soil groundwater pollution event. The 3D printing nozzle comprises a shell, a hollow first stirring shaft, a hollow second stirring shaft, a power source and an air source. A feeding hole, a discharging hole and an air injection hole are formed in the shell; second stirring blades are arranged on the outer wall of the second stirring shaft, the first stirring shaft is sleeved with the second stirring shaft, first stirring blades are arranged on the outer wall of the lower portion of the first stirring shaft, and gas dispersion holes are formed in the wall face of the lower portion of the first stirring shaft; the power source drives the first stirring shaft and the second stirring shaft to rotate; the air source is respectively connected with the hollow cavity of the first stirring shaft and the air injection hole.

Description

Technical Field

[0001] The present invention relates to a 3D printing nozzle and a printing method, and in particular to a 3D printing nozzle and a printing method for printing a barrier to a contaminated site. Background Art

[0002] After a sudden soil and groundwater pollution incident at a site, rapid isolation of the site surface is an effective way to cut off the spread of pollution. Rapidly building a barrier to a contaminated site through information-based and mechanized 3D printing technology can effectively improve the efficiency of emergency disposal and reduce the harm to rescue personnel in traditional emergency disposal technologies. At present, printing materials represented by cement-activated steel slag have the disadvantages of long molding time, and the cement component in the material has high energy consumption and high carbon emissions. The rapid carbonization technology can not only effectively improve the reactivity of cement-activated steel slag printing materials and improve the service performance of the printed barrier, but also achieve effective carbon fixation, which has significant environmental benefits. However, the printability of the printing material after rapid carbonization is rapidly weakened, which will affect the high-quality printing construction of the subsequent barrier. Therefore, how to achieve the simultaneous rapid carbonization and printing construction of weakly reactive silicate printing materials represented by cement-activated steel slag has always been a technical problem faced by this field. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a 3D printing nozzle and a printing method for printing a barrier for a contaminated site are provided, which can realize the simultaneous rapid carbonization and printing construction of the printing material, form a composite barrier with a high sealing effect, and significantly improve the emergency disposal efficiency of sudden soil and groundwater pollution incidents at the site.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a 3D printing nozzle for printing a barrier to contaminated sites, comprising a shell, a hollow first stirring shaft, a hollow second stirring shaft, a power source and a gas source; wherein the shell is provided with a material inlet, a material outlet and a gas injection hole; the second stirring shaft and the shell are connected by a bearing, the outer wall of the second stirring shaft is provided with a second stirring blade, and the second stirring blade is located in the inner cavity of the shell; the second stirring shaft is sleeved on the outer side of the first stirring shaft, the first stirring shaft and the second stirring shaft are connected by a bearing, and there is a gap between the first stirring shaft and the second stirring shaft; the upper part of the first stirring shaft passes through the top end of the second stirring shaft, the lower part of the first stirring shaft passes through the bottom end of the second stirring shaft, the lower outer wall of the first stirring shaft is provided with a first stirring blade, the first stirring blade is located in the inner cavity of the shell, and the lower wall of the first stirring shaft is provided with a gas dispersion hole; the top of the first stirring shaft and the top of the second stirring shaft are respectively connected to the power source, and the power source drives the first stirring shaft and the second stirring shaft to rotate; the gas source is respectively connected to the hollow cavity and the gas injection hole of the first stirring shaft.

[0006] As a preferred example, the feed port is located on the upper side of the shell, and the discharge port is located at the bottom of the shell; the air injection holes are through holes, which are arranged obliquely upward from the outside to the inside of the shell; the air injection holes are arranged in multiple layers along the axial direction of the shell; at least 3 air injection holes are provided in the first air injection holes of each layer.

[0007] As a preferred example, the 3D printing nozzle for printing a barrier to isolate a contaminated site further includes a first pressure regulating valve, a connecting valve, a first connecting pipe, and a second connecting pipe, wherein one connecting valve is arranged in each gas injection hole; in the gas injection holes located in the same layer, the connecting valves are connected through the first connecting pipe; the first connecting pipes on different layers are connected through the second connecting pipe; the gas source is connected to the first connecting pipe or the second connecting pipe through a fourth connecting pipe, and the first pressure regulating valve is arranged in the fourth connecting pipe.

[0008] As a preferred example, an injection core assembly is provided in the injection hole, and the injection core assembly includes a fixing part, an outer shell, and a spring, a sealing plate and a core body located in the outer shell, the outer shell is fixed in the inner cavity of the first injection hole by a fixing part, one end of the spring is fixedly connected to one end of the outer shell, and the other end of the spring is fixedly connected to the sealing plate; the core body is provided with a hollow through hole, and the air inlet end and the air outlet end of the core body are both openings; the sealing plate and the air outlet end of the core body are opposite, and the sealing plate can seal the air outlet end of the core body; the air inlet end of the core body is connected to the connecting valve.

[0009] As a preferred example, the power source includes a motor with a power output shaft, a first gear and a second gear, the first gear is fixedly connected to the upper outer wall of the first stirring shaft, and the second gear is fixedly connected to the upper outer wall of the second stirring shaft; the power output shaft is respectively adapted to the first gear and the second gear, driving the first gear and the second gear to rotate in opposite directions; it also includes a third connecting pipe and a second pressure regulating valve, the air source is connected to the hollow cavity of the first stirring shaft through the third connecting pipe, and the second pressure regulating valve is arranged in the third connecting pipe; it also includes a first sealing ring and a second sealing ring, the first sealing ring is embedded between the first stirring shaft and the second stirring shaft, and is located at the bottom of the inner cavity of the second stirring shaft; the second sealing ring is embedded between the second stirring shaft and the shell.

[0010] In a second aspect, the present invention further provides a method for printing a barrier, wherein the barrier comprises, from bottom to top, a first bearing layer, a pollution-blocking layer, and a second bearing layer; the method comprises:

[0011] Step 1: Use a 3D printing nozzle to build the first bearing layer;

[0012] Step 2: On top of the first bearing layer, a pollution-resistant layer is constructed using a 3D printing nozzle;

[0013] Step 3: construct a second bearing layer above the anti-fouling layer using a 3D printing nozzle.

[0014] As a preferred example, the step 1 specifically includes:

[0015] Step 101, regulating the first pressure regulating valve to increase the air pressure, so that the gas injection core assembly is in an open state, and the carbon dioxide gas passes through the gas injection core assembly and the gas injection hole to enter the inner cavity of the shell; opening the second pressure regulating valve, so that the carbon dioxide gas passes through the gas dispersion hole located on the first stirring shaft and enters the inner cavity of the shell;

[0016] Step 102, start the motor to make the first stirring shaft and the second stirring shaft rotate in opposite directions;

[0017] Step 103, the printing material flows into the shell from the feed port of the 3D printing nozzle, and the printing material and the carbon dioxide gas entering the shell from the gas injection hole and the gas dispersion hole undergo a carbonization reaction under the cutting and stirring of the first stirring shaft and the second stirring shaft; after the carbonization reaction is completed, the carbon dioxide gas is continuously introduced into the printing material to prepare the first bearing layer printing material;

[0018] Step 104, moving the 3D printing nozzle, discharging the first bearing layer printing material made in step 103 from the discharge port of the 3D printing nozzle, and paving it to form a first bearing layer.

[0019] As a preferred example, the step 2 specifically includes:

[0020] Step 201, regulating the first pressure regulating valve to keep the gas injection core assembly in a closed state;

[0021] Step 202: The printing material flows into the shell from the feed port of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft and the second stirring shaft, the printing material and the carbon dioxide entering the shell from the gas dispersion hole undergo a carbonization reaction to form a pollution-proof layer printing material.

[0022] Step 203: Move the 3D printing nozzle above the first supporting layer, discharge the anti-fouling layer printing material made in step 202 from the discharge port of the 3D printing nozzle, and spread it above the first supporting layer to form an anti-fouling layer.

[0023] As a preferred example, the step 3 specifically includes:

[0024] Step 301, regulating the first pressure regulating valve to increase the air pressure, so that the gas injection core assembly is in an open state, and the carbon dioxide gas passes through the gas injection core assembly and the gas injection hole and enters the inner cavity of the shell;

[0025] Step 302: The printing material flows into the shell from the feed port of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft and the second stirring shaft, the printing material and the carbon dioxide gas entering the shell from the gas injection hole and the gas dispersion hole undergo a carbonization reaction. After the carbonization reaction is completed, the carbon dioxide gas is continuously introduced into the printing material to prepare a second bearing layer printing material.

[0026] Step 303: above the anti-fouling layer, move the 3D printing nozzle, discharge the second supporting layer printing material made in step 302 from the discharge port of the 3D printing nozzle, and spread it on the anti-fouling layer to form the second supporting layer.

[0027] As a preferred example, in step 101, step 201 and step 301, the pressure p of the carbon dioxide gas entering the inner cavity of the shell after adjustment by the first pressure regulating valve is equal to the pressure p of the carbon dioxide gas entering the inner cavity of the shell after adjustment by the second pressure regulating valve; the carbon dioxide gas pressure p is calculated according to formula (1):

[0028] p=p0-a×(f-f0)-b×(R-R0) Formula (1) In the formula, p is the carbon dioxide gas pressure after adjustment by the first pressure regulating valve, in kPa; p0 is the reference pressure, which is 1000, in kPa; a is the adjustment coefficient related to the physical state of the printing material, in kPa / mm; f is the fluidity of the printing material, in mm; f0 is the reference fluidity of the printing material, which is 100, in mm; b is the adjustment coefficient related to the motion state of the first stirring shaft, in kPa / rpm; R is the rotation speed of the first stirring shaft, in rpm; the rotation speed of the first stirring shaft is the same as the rotation speed of the second stirring shaft, and R0 is the reference rotation speed of the first stirring shaft, which is 15, in rpm;

[0029] The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve is equal to the total flow rate of carbon dioxide gas flowing through the second pressure regulating valve. The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve is calculated according to formula (2):

[0030] Q g =10 3 ×c×Q s +10 3 ×d×A×Q s Formula (2)

[0031] In the formula, Q g is the total flow rate of carbon dioxide gas flowing through the first pressure regulating valve, in l / min; c is the adjustment coefficient related to the physical characteristics of the printing material, which is a dimensionless variable; Q s The feed speed of the printing material, in m 3 / min; d is the adjustment coefficient related to the chemical characteristics of the printing material, which is a dimensionless variable; A is the alkalinity of the printing material, which is the mass ratio of the alkaline oxide to the acidic oxide in the printing material.

[0032] Compared with the prior art, the 3D printing nozzle and printing method for printing a barrier for a contaminated site of the present invention have significant advantages: (1) It can realize the synchronous rapid carbonization and printing construction of the printing material, form a composite barrier with a high sealing effect, and significantly improve the emergency disposal efficiency of sudden site soil and groundwater pollution incidents. (2) The 3D printing nozzle includes a shell, a hollow first stirring shaft, a hollow second stirring shaft, a power source and a gas source; the shell is provided with a feed inlet, a discharge port and a gas injection hole; the second stirring shaft and the shell are connected by a bearing, the second stirring shaft is sleeved on the outside of the first stirring shaft, the outer wall of the second stirring shaft is provided with a second stirring blade, the lower outer wall of the first stirring shaft is provided with a first stirring blade, and the lower wall of the first stirring shaft is provided with a gas dispersion hole; the power source drives the first stirring shaft and the second stirring shaft to rotate; the gas source is respectively connected to the hollow cavity and the gas injection hole of the first stirring shaft. The 3D printing nozzle of this structure provides a tool that can realize the synchronous rapid carbonization and printing of weakly reactive silicate printing materials represented by cement activated steel slag. (3) The amount of carbon dioxide gas entering the inner cavity of the shell is controlled through the gas injection holes and the gas dispersion holes, so as to realize efficient and rapid carbonization and printing construction of the printing material, form a barrier layer with different performance requirements, and improve the emergency disposal efficiency of soil and groundwater pollution incidents at the sudden site. (4) In equations (1) and (2), the influence of the physical and chemical indicators such as the fluidity and alkalinity of the printing material on the mechanical and barrier properties of the hardened barrier is considered, and the input pressure and carbon dioxide injection amount of the printing process are designed, so as to realize the directional design of the service performance parameters of the barrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A cross-sectional view of a 3D printing nozzle according to an embodiment of the present invention;

[0034] Figure 2 for Figure 1 A-A' section view;

[0035] Figure 3 Schematic diagram of the structure of the gas injection hole and the gas injection core in an embodiment of the present invention.

[0036] The figure includes: shell 1, feed port 101, discharge port 102, gas injection hole 103, first pressure regulating valve 1031, connecting valve 1032, first connecting pipe 1033, second connecting pipe 1034, spring 201, sealing sheet 202, core 203, fixing part 204, shell 205, first stirring shaft 3, gas dispersion hole 301, first stirring blade 4, second stirring shaft 5, second stirring blade 6, first sealing ring 7, second sealing ring 8, gas source 9, third connecting pipe 901, second pressure regulating valve 902, motor 111, power output shaft 1111, first gear 112, second gear 113, protective net 12. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in detail below. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0038] like Figure 1 and Figure 2 As shown, a 3D printing nozzle for printing a barrier to contaminated sites according to an embodiment of the present invention comprises a shell 1, a hollow first stirring shaft 3, a hollow second stirring shaft 5, a power source and a gas source 9. The second stirring shaft 5 is hollow for setting the first stirring shaft 3. The first stirring shaft 3 is hollow for conveying carbon dioxide gas. The shell 1 is provided with an inlet 101, an outlet 102 and a gas injection hole 103. The second stirring shaft 5 and the shell 1 are connected by a bearing, and the outer wall of the second stirring shaft 5 is provided with a second stirring blade 6, and the second stirring blade 6 is located in the inner cavity of the shell 1. The second stirring shaft 5 is set on the outside of the first stirring shaft 3, and the first stirring shaft 3 and the second stirring shaft 5 are connected by a bearing, and there is a gap between the first stirring shaft 3 and the second stirring shaft 5; the upper part of the first stirring shaft 3 passes through the top end of the second stirring shaft 5, and the lower part of the first stirring shaft 3 passes through the bottom end of the second stirring shaft 5, and the lower outer wall of the first stirring shaft 3 is provided with a first stirring blade 4, and the first stirring blade 4 is located in the inner cavity of the shell 1, and the lower wall of the first stirring shaft 3 is provided with a gas dispersion hole 301. The top of the first stirring shaft 3 and the top of the second stirring shaft 5 are respectively connected to a power source, which drives the first stirring shaft 3 and the second stirring shaft 5 to rotate. The gas source 9 is respectively connected to the hollow cavity of the first stirring shaft 3 and the gas injection hole 103.

[0039] In the 3D printing nozzle of the above embodiment, the printing material enters the inner cavity of the shell 1 from the feed port 101, and then flows out of the shell 1 from the discharge port 102. Start the power source, and the power source drives the first stirring shaft 3 and the second stirring shaft 5 to rotate. In this way, the first stirring blade 4 and the second stirring blade 6 also rotate accordingly. Start the gas source 9, the gas dispersion hole 301, or the gas dispersion hole 301 and the gas injection hole 103, and input carbon dioxide gas into the inner cavity of the shell 1. When the printing material is located in the inner cavity of the shell 1, the carbon dioxide gas and the printing material are fully mixed and reacted under the rotation of the first stirring blade 4 and the second stirring blade 6. By controlling the intake amount of carbon dioxide gas, the activation and excitation of carbon dioxide and the weakly reactive silicate in the printing material is achieved, and the reactivity of the printing material is improved. In addition, carbon dioxide that has not undergone carbonization reaction can also be wrapped in the printing material, forming tiny bubbles in the printing material, so that the printing material forms a closed-cell multi-bubble structure, which reduces the quality of the material on the basis of ensuring the excellent barrier performance of the barrier barrier, and reduces the degradation and damage of the barrier barrier during maintenance and service. By adjusting, the amount of carbon dioxide gas inputted into the inner cavity of the housing 1 by the gas dispersion holes 301 and the gas injection holes 103 can be controlled. Preferably, the gas dispersion holes 301 are arranged obliquely downward from the inner cavity of the first stirring shaft 3 to the outside. This can prevent the printing material in the housing 1 from entering the gas dispersion holes 301 and blocking the gas dispersion holes 301.

[0040] Preferably, the feed inlet 101 is located on the upper side of the housing 1, and the discharge port 102 is located at the bottom of the housing 1; the gas injection hole 103 is a through hole, which is arranged obliquely upward from the outside to the inside of the housing 1. The feed inlet 101 is located on the upper side of the housing 1, so that the printing material entering the housing 1 automatically flows downward under the action of gravity. The discharge port 102 is located at the bottom of the housing 1, which facilitates the printing material to flow out of the housing 1. The gas injection hole 103 is a through hole, which is arranged on the side of the housing 1, so that the carbon dioxide gas entering the inner cavity of the housing 1 from the gas injection hole 103 can flow to the printing material more evenly. The gas injection holes 103 are arranged obliquely upward from the outside to the inside of the shell 1, and an airflow in an oblique upward direction is formed in the inner cavity of the shell 1. Under the cutting action of the first stirring blade, the second stirring blade and the airflow, the printing material is three-dimensionally mixed in the inner cavity of the shell 1, providing a larger contact area for the rapid carbonization reaction of silicates and alkaline oxides in the printing material, which can increase the activity of the printing material and effectively reduce the false coagulation phenomenon caused by local carbonization. The gas injection holes 103 are arranged in multiple layers along the axial direction of the shell 1; at least three gas injection holes 103 are arranged in each layer of the first gas injection holes. The provision of multiple gas injection holes 103 can accelerate the injection rate of carbon dioxide in the inner cavity of the shell 1 and accelerate the carbonization reaction.

[0041] Preferably, the 3D printing nozzle further includes a first pressure regulating valve 1031, a connecting valve 1032, a first connecting pipe 1033, and a second connecting pipe 1034. A connecting valve 1032 is provided in each gas injection hole 103; in the gas injection holes 103 located in the same layer, the connecting valves 1032 are connected through the first connecting pipe 1033; and the first connecting pipes 1033 in different layers are connected through the second connecting pipe 1034. The gas source 9 is connected to the first connecting pipe 1033 or the second connecting pipe 1034 through a fourth connecting pipe, and the first pressure regulating valve 1031 is provided in the fourth connecting pipe. The carbon dioxide gas flowing out of the gas source 9, after adjusting the air pressure through the first pressure regulating valve 1031, flows into the first connecting pipe 1033 and the second connecting pipe 1034, and then flows into the gas injection hole 103 through the connecting valve 1032, and finally flows out from the gas injection hole 103, enters the inner cavity of the shell 1, and mixes with the printing material. This structure can achieve the same pressure of carbon dioxide gas flowing out of all the gas injection holes 103. By setting equal pressure, it can effectively ensure that the printing material moves perpendicular to the axial direction of the first stirring shaft 3 and the second stirring shaft 5 in the inner cavity of the shell 1, avoiding the rapid discharge of the printing material from the discharge port 102 due to the pressure difference between the side wall and the center position of the inner cavity of the shell 1, thereby reducing the carbonization degree and homogeneity of the printing material.

[0042] Preferably, Figure 3As shown, a gas injection core assembly is provided in the gas injection hole 103. The gas injection core assembly includes a fixing member 204, a shell 205, and a spring 201, a sealing sheet 202 and a core body 203 located in the shell 205. The shell 205 is fixed in the inner cavity of the first gas injection hole 1031 by the fixing member 204, one end of the spring 201 is fixedly connected to one end of the shell 205, and the other end of the spring 201 is fixedly connected to the sealing sheet 202. The spring 201 always applies an extrusion force to the sealing sheet 202. The core body 203 is provided with a hollow through hole, and the gas inlet end and the gas outlet end of the core body 203 are both open; the sealing sheet 202 and the gas outlet end of the core body 203 are opposite, and the sealing sheet 202 can block the gas outlet end of the core body 203; the gas inlet end of the core body 203 is connected to the connecting valve 1032. The gas injection core assembly is provided to allow carbon dioxide gas to pass into the inner cavity of the shell 1, while preventing the printing material in the inner cavity of the shell 1 from flowing into the connecting valve 1032 and causing blockage. When it is necessary to introduce carbon dioxide gas into the inner cavity of the shell 1, the carbon dioxide gas flows out from the connecting valve 1032, passes through the inner cavity of the core 203, and uses the gas pressure to push the sealing sheet 202 away from the gas outlet end of the core 203. The spring 201 is compressed, and there is a gap between the sealing sheet 202 and the gas outlet end of the core 203, so that the carbon dioxide gas flows out from the gas outlet end of the core 203, and then flows out of the shell 205 and enters the inner cavity of the shell 1. When it is not necessary to introduce carbon dioxide gas into the inner cavity of the shell 1, the connecting valve 1032 does not introduce carbon dioxide gas. Under the action of the spring 201, the sealing sheet 202 and the gas outlet end of the core 203 are adapted to play the role of closing the inner cavity of the core 203, thereby preventing the printing material in the shell 1 from flowing into the inner cavity of the core 203, flowing back into the connecting valve 1032, and blocking the carbon dioxide gas flow path.

[0043] Preferably, the power source includes a motor 111 with a power output shaft 1111, a first gear 112 and a second gear 113, the first gear 112 is fixedly connected to the upper outer wall of the first stirring shaft 3, and the second gear 113 is fixedly connected to the upper outer wall of the second stirring shaft 5; the power output shaft 1111 is respectively adapted to the first gear 112 and the second gear 113, driving the first gear 112 and the second gear 113 to rotate in the opposite direction. During operation, the motor 111 is started, and the power output shaft 1111 rotates. The first gear 112 and the second gear 113 are respectively adapted to the power output shaft 1111, and the power output shaft 1111 drives the first gear 112 and the second gear 113 to rotate. Preferably. The first gear 112 is located above the power output shaft 1111, and the second gear 113 is located below the power output shaft 1111, and the first gear 112 and the second gear 113 rotate in the opposite direction. In this way, the first stirring blade 4 and the second stirring blade 6 also rotate in the opposite direction. By rotating the first stirring blade 4 and the second stirring blade 6 in opposite directions, horizontal cutting and stirring of the printed material can be achieved. At the same time, the oblique cutting effect of the carbon dioxide gas flow in the gas dispersion hole 301 of the shell 1 and the gas injection hole 103 forms a three-dimensional spatial movement, which accelerates the carbonization speed of the printed material and improves the stirring effect.

[0044] Preferably, the 3D printing nozzle further includes a third connecting pipe 901 and a second pressure regulating valve 902. The gas source 9 is connected to the hollow cavity of the first stirring shaft 3 through the third connecting pipe 901, and the second pressure regulating valve 902 is arranged in the third connecting pipe 901. When the gas source 9 is started, the carbon dioxide gas flows into the hollow cavity of the first stirring shaft 3 through the third connecting pipe 901, and then flows into the inner cavity of the housing 1 through the gas dispersion hole 301. By setting the second pressure regulating valve 902, the gas pressure in the third connecting pipe 901 is adjusted, and then the pressure of the carbon dioxide gas flowing out of the gas dispersion hole 301 is adjusted.

[0045] Preferably, the 3D printing nozzle further includes a first sealing ring 7 and a second sealing ring 8, wherein the first sealing ring 7 is embedded between the first stirring shaft 3 and the second stirring shaft 5 and is located at the bottom of the inner cavity of the second stirring shaft 5; the second sealing ring 8 is embedded between the second stirring shaft 5 and the housing 1. The first sealing ring 7 is provided to prevent the printing material in the inner cavity of the housing 1 from entering the gap between the first stirring shaft 3 and the second stirring shaft 5. The second sealing ring 8 is provided to prevent the printing material in the inner cavity of the housing 1 from flowing out of the housing 1 from the gap between the second stirring shaft 5 and the housing 1.

[0046] Preferably, a protective net 12 is further provided in the gas injection hole 103. The protective net 12 can effectively prevent the printing material in the inner cavity of the shell 1 from entering the gas injection hole 103. At the same time, the protective net 12 is in a mesh shape, which can make the carbon dioxide gas flow out of the gas injection hole 103 and enter the inner cavity of the shell 1.

[0047] The embodiment of the present invention also provides a method for printing a barrier using the 3D printing nozzle of the above embodiment or preferred example. The barrier comprises a first bearing layer, a pollution-blocking layer, and a second bearing layer from bottom to top. The method comprises:

[0048] Step 1: Use a 3D printing nozzle to build the first bearing layer;

[0049] Step 2: On top of the first bearing layer, a pollution-resistant layer is constructed using a 3D printing nozzle;

[0050] Step 3: construct a second bearing layer above the anti-fouling layer using a 3D printing nozzle.

[0051] By using the 3D printing nozzle of the above embodiment or preferred example to print the barrier barrier, fast and efficient printing of the barrier barrier can be achieved, which is suitable for emergency pollution prevention scenarios. During printing, by controlling the flow rate of carbon dioxide gas in the 3D printing nozzle, the printing of barrier layers with different performances can be achieved. In this embodiment, the barrier barrier includes a first bearing layer, a pollution-blocking layer, and a second bearing layer from bottom to top. The bottom surface of the first bearing layer is directly in contact with the surface of the contaminated site, and is used to bear the gravity of the barrier barrier and subsequent emergency personnel and emergency equipment, and at the same time, overcome the deformation and damage of the barrier barrier under the action of foundation settlement. Therefore, the first bearing layer needs to have a higher strength. The pollution-blocking layer is located above the first bearing layer, and is used to prevent the polluted gas from volatilizing to the outside, and has a higher barrier performance. Therefore, the pollution-blocking layer needs to have as few open pores as possible. The second bearing layer is located above the pollution-blocking layer, and is used for direct contact with emergency personnel and emergency equipment, and has considerable buffering capacity for external loads. Therefore, the second bearing layer needs to have a higher strength and the performance of absorbing external energy.

[0052] Preferably, in the above printing method, step 1 specifically includes:

[0053] Step 101, regulate the first pressure regulating valve 1031, increase the air pressure, and make the gas injection core assembly in an open state. Use carbon dioxide gas to open the sealing sheet 22, and the spring 201 is compressed, so that the gas injection core assembly is in an open state. The carbon dioxide gas passes through the gas injection core assembly and the gas injection hole 103 and enters the inner cavity of the shell 1. Open the second pressure regulating valve 902, so that the carbon dioxide gas passes through the gas dispersion hole 301 located on the first stirring shaft 3 and enters the inner cavity of the shell 1. The gas injection hole 103 and the gas dispersion hole 301 both flow carbon dioxide gas into the inner cavity of the shell 1.

[0054] Step 102 , starting the motor 111 to rotate the first stirring shaft 3 and the second stirring shaft 5 in opposite directions.

[0055] Step 103, the printing material flows into the shell 1 from the feed port 101 of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft 3 and the second stirring shaft 5, the printing material and the carbon dioxide gas entering the shell 1 from the gas injection hole 103 and the gas dispersion hole 301 undergo a carbonization reaction. The rapid carbonization reaction can form acidic pore water on the surface of the inert silicate particles in the steel slag, triggering the hydrolysis of silicate minerals. At the same time, the carbonization reaction is an exothermic process, and the heat released can enhance the phase transformation of silicates in the steel slag. In addition, the dicalcium silicate, tricalcium silicate and calcium oxide in the steel slag can effectively fix carbon dioxide through the rapid carbonization reaction, generate calcium carbonate crystals, and increase its strength and stability. After the steel slag is carbonized, the calcium carbonate particles fill the internal voids, making the internal arrangement of the system more compact and reducing the porosity. After the carbonization reaction is completed, carbon dioxide gas is continuously introduced into the printing material to form the first bearing layer printing material. After the carbonization reaction is completed, the remaining carbon dioxide gas forms a certain volume of discontinuous closed pores in the hardened printing material, which quickly increases the strength of the first bearing layer of the barrier and significantly reduces the weight of the first bearing layer, reducing the risk of later cracking of the barrier.

[0056] Step 104 , moving the 3D printing nozzle, discharging the first bearing layer printing material made in step 103 from the discharge port 102 of the 3D printing nozzle, and paving the first bearing layer.

[0057] In step 1, carbon dioxide gas is injected into the inner cavity of the shell 1 through the gas injection holes 103 and the gas dispersion holes 301 to obtain a first bearing layer with required performance.

[0058] After step 1 is completed, preferably, step 2 specifically includes:

[0059] Step 201, regulating the first pressure regulating valve 1031 to put the gas injection core assembly in a closed state. By changing the values ​​of a and b in formula (1), the pressure of the carbon dioxide gas adjusted by the first pressure regulating valve 1031 is changed. When the pressure of the carbon dioxide gas adjusted by the first pressure regulating valve 1031 is less than or equal to the pressure of the spring 201 on the sealing sheet 202, the sealing sheet 202 and the gas outlet end of the core body 203 touch each other, so that the gas injection core assembly is in a closed state. The gas injection hole 103 does not inject carbon dioxide gas into the inner cavity of the shell 1.

[0060] Step 202: The printing material flows into the housing 1 from the feed port 101 of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft 3 and the second stirring shaft 5, the printing material and the carbon dioxide entering the housing 1 from the gas dispersion hole 301 undergo a carbonization reaction to form a pollution-blocking layer printing material. The carbonization reaction increases the reactivity of the inert components in the printing material. After the carbonization reaction is completed, there is no carbon dioxide gas remaining in the printing material, and the printing material is more dense, which effectively increases the pollution interception capacity of the barrier.

[0061] Step 203, above the first supporting layer, move the 3D printing nozzle, discharge the anti-fouling layer printing material made in step 202 from the discharge port 102 of the 3D printing nozzle, and spread it on the first supporting layer to form an anti-fouling layer.

[0062] To improve printing efficiency, the printing end point of the first carrier layer is the printing starting point of the anti-fouling layer.

[0063] After step 2 is completed, preferably, step 3 specifically includes:

[0064] Step 301, regulate the first pressure regulating valve 1031, increase the air pressure, make the gas injection core assembly in the open state, and the carbon dioxide gas passes through the gas injection core assembly and the gas injection hole 103 and enters the inner cavity of the shell 1. At this time, the second pressure regulating valve 902 is in the open state, and the carbon dioxide gas passes through the gas dispersion hole 301 located on the first stirring shaft 3 and enters the inner cavity of the shell 1.

[0065] Step 302, the printing material flows into the shell 1 from the feed port 101 of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft 3 and the second stirring shaft 5, the printing material and the carbon dioxide gas entering the shell 1 from the gas injection hole 103 and the gas dispersion hole 301 undergo a carbonization reaction; after the carbonization reaction is completed, carbon dioxide gas is continuously introduced into the printing material to form a second bearing layer printing material. Similar to step 102, the carbonization reaction can significantly increase the formation of acidic pore water on the surface of the inert silicate particles in the steel slag, triggering the hydrolysis of silicate minerals. At the same time, the carbonization reaction is an exothermic process, and the heat released can increase the phase transformation of silicates in the steel slag. In addition, the dicalcium silicate, tricalcium silicate and calcium oxide in the steel slag effectively fix carbon dioxide to form calcium carbonate crystals through the rapid carbonization reaction, increasing its strength and stability. After the steel slag is carbonized, the calcium carbonate particles fill the internal voids, making the internal arrangement of the system more compact and reducing the porosity. After the carbonization reaction is completed, the remaining carbon dioxide gas forms a certain volume of discontinuous closed pores in the hardened printing material, which quickly increases the strength of the second bearing layer of the barrier and significantly reduces the weight of the second bearing layer, reducing the risk of cracking of the barrier in the later stage.

[0066] Step 303: Move the 3D printing nozzle above the anti-fouling layer, discharge the second supporting layer printing material made in step 302 from the discharge port 102 of the 3D printing nozzle, and spread it on the anti-fouling layer to form a second supporting layer.

[0067] To improve printing efficiency, the printing end point of the anti-fouling layer is the printing starting point of the second supporting layer.

[0068] In step 101, step 201 and step 301, the pressure p of carbon dioxide gas entering the inner cavity of the shell 1 after adjustment by the first pressure regulating valve 1031 is equal to the pressure p of carbon dioxide gas entering the inner cavity of the shell 1 after adjustment by the second pressure regulating valve 902. By setting equal pressures, it is possible to effectively ensure that the printing material moves perpendicularly to the axial direction of the first stirring shaft 3 inside the inner cavity of the shell 1, avoiding the rapid discharge of the printing material from the discharge port 102 due to the pressure difference between the side wall and the center position of the inner cavity of the shell 1, thereby reducing the carbonization degree and homogeneity of the printing material. The carbon dioxide gas pressure p is calculated according to formula (1):

[0069] p=p0-a×(f-f0)-b×(R-R0) Formula (1) In the formula, p is the carbon dioxide gas pressure adjusted by the first pressure regulating valve 1031, in kPa; p0 is the reference pressure, which is 1000, in kPa; a is the adjustment coefficient related to the physical state of the printing material, in kPa / mm; f is the fluidity of the printing material, in mm; f0 is the reference fluidity of the printing material, which is 100, in mm; b is the adjustment coefficient related to the motion state of the first stirring shaft, in kPa / rpm; R is the rotation speed of the first stirring shaft 3, in rpm; the rotation speed of the first stirring shaft 3 is the same as the rotation speed of the second stirring shaft 5, and R0 is the reference rotation speed of the first stirring shaft 3, which is 15, in rpm.

[0070] The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve 1031 is equal to the total flow rate of carbon dioxide gas flowing through the second pressure regulating valve 902. By setting equal flow rates, it is possible to effectively ensure that the printing material undergoes a uniform carbonization reaction in the inner cavity of the housing 1, reduce the phenomenon of false coagulation of the printing material caused by local carbonization of the printing material, and thus improve the homogeneity of the barrier after hardening and molding. The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve (1031) is calculated according to formula (2):

[0071] Q g =10 3 ×c×Q s +10 3 ×d×A×Q s Formula (2)

[0072] In the formula, Q g is the total flow rate of carbon dioxide gas flowing through the first pressure regulating valve 1031, in l / min; c is the adjustment coefficient related to the physical characteristics of the printing material, which is a dimensionless variable; Q s The feed speed of the printing material, in m 3 / min; d is the adjustment coefficient related to the chemical characteristics of the printing material, which is a dimensionless variable; A is the alkalinity of the printing material, which is the mass ratio of alkaline oxides to acidic oxides in the printing material. Alkaline oxides include CaO and MgO, etc. Acidic oxides include SiO2, Al2O3 and Fe2O3, etc.

[0073] By changing the values ​​of a and b, the first pressure regulating valve 1031 is regulated to make the gas injection core assembly in an open state or a closed state. By changing the values ​​of a and b, the pressure of the carbon dioxide gas adjusted by the first pressure regulating valve 1031 is changed. When the pressure of the carbon dioxide gas adjusted by the first pressure regulating valve 1031 is greater than the pressure of the spring 201 on the sealing piece 202, the sealing piece 202 is separated from the air outlet end of the core body 203, so that the gas injection core assembly is in an open state. When the pressure of the carbon dioxide gas adjusted by the first pressure regulating valve 1031 is less than or equal to the pressure of the spring 201 on the sealing piece 202, the sealing piece 202 and the air outlet end of the core body 203 touch each other, so that the gas injection core assembly is in a closed state. Preferably, when the first bearing layer is constructed by using a 3D printing nozzle in step 1, the value range of a in formula (1) is: 3-6 kPa / mm; the value range of b is: 5-9 kPa / rpm; the value range of c in formula (2) is: 0.10-0.25; the value range of d is: 0.05-0.15. When the anti-fouling layer is constructed by using a 3D printing nozzle in step 2, the value range of a in formula (1) is: 5-8 kPa / mm; the value range of b is: 7-11 kPa / rpm; the value of c in formula (2) is: 0; the value range of d is: 0.05-0.15. In step 3, when the second bearing layer is constructed using a 3D printing nozzle, the value range of a in formula (1) is: 4-7 kPa / mm; the value range of b is: 6-10 kPa / rpm; the value range of c in formula (2) is: 0.05-0.12; the value range of d is: 0.05-0.15.

[0074] The following is an example of how to calculate the pressure p of the carbon dioxide gas after being regulated by the first pressure regulating valve 1031 and the total flow rate Q of the carbon dioxide gas flowing through the first pressure regulating valve 1031 according to formula (1) and formula (2). g The alkalinity A of the printing material in this embodiment is 2.60, and the feeding speed Q of the printing material is s Set to 0.03m 3 The reference pressure p0 is 1000 kPa, the reference fluidity f0 of the printing material is 100 mm, and the reference rotation speed R0 of the first stirring shaft is 15 rpm.

[0075] The method of printing a barrier using the 3D printing nozzle of the above embodiment or preferred example includes:

[0076] In step 1, the first bearing layer is constructed using a 3D printing nozzle, the fluidity f of the printing material is set to 180 mm, and the rotation speed R of the first stirring shaft 3 is set to 45 rpm. The value of a in formula (1) is 6 kPa / mm, the value of b is 9 kPa / rpm, the value of c in formula (2) is 0.25, and the value of d is 0.10. Then, the carbon dioxide gas pressure p adjusted by the first pressure regulating valve 1031 is 1000-6×(180-100)-9×(45-15)=250 kPa, and the total flow rate Q of the carbon dioxide gas flowing through the first pressure regulating valve 1031 is g For 10 3 ×0.25×0.03+10 3 ×0.10×2.60×0.03=15.3l / min.

[0077] Step 2, use a 3D printing nozzle to build a pollution-proof layer. Because this layer does not produce gaps in the barrier structure, the fluidity of the printing material and the rotation speed of the first stirring shaft 3 are appropriately reduced. The fluidity f of the printing material is set to 160 mm, and the rotation speed R of the first stirring shaft 3 is set to 40 rpm. The value of a in formula (1) is 5 kPa / mm, the value of b is 7 kPa / rpm, the value of c in formula (2) is 0, and the value of d is 0.05. Then the carbon dioxide gas pressure p adjusted by the first pressure regulating valve 1031 is 1000-5×(160-100)-7×(40-15)=525 kPa, and the total flow rate of carbon dioxide gas flowing through the first pressure regulating valve 1031 is Q g For 10 3 ×0×0.03+10 3 ×0.05×2.60×0.03=3.9l / min.

[0078] Step 3, using a 3D printing nozzle to build the second bearing layer. The fluidity f of the printing material is set to 180 mm, and the rotation speed R of the first stirring shaft 3 is set to 45 rpm. In formula (1), a is set to 4 kPa / mm; b is set to 10 kPa / rpm; c is set to 0.08; d is set to 0.15. Then the carbon dioxide gas pressure p adjusted by the first pressure regulating valve 1031 is 1000-4×(180-100)-10×(45-15)=380 kPa; the total flow rate of carbon dioxide gas flowing through the first pressure regulating valve 1031 is 10 3 ×0.08×0.03+10 3 ×0.15×2.60×0.03=14.1l / min.

[0079] It can be seen from this embodiment that the barrier printed by the 3D printing nozzle and method of the present invention has a carbon dioxide gas pressure p of 250 kPa and a total carbon dioxide flow rate Q of 250 kPa during the printing process of the first bearing layer.g is 15.3 l / min; during the printing process of the anti-fouling layer, the carbon dioxide gas pressure p is 525 kPa, and the total carbon dioxide flow rate Q g is 3.9l / min; during the printing process of the second bearing layer, the carbon dioxide gas pressure p is 380kPa, and the total carbon dioxide flow rate Q g By adjusting the working mode of the 3D printing nozzle for printing the barrier of the contaminated site of the present invention and optimizing the carbon dioxide gas pressure and the total carbon dioxide flow rate during the printing process, it is possible to ensure that the barrier has excellent service performance.

[0080] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A 3D printing nozzle for printing a barrier to contaminated sites, characterized in that: It comprises a shell (1), a hollow first stirring shaft (3), a hollow second stirring shaft (5), a power source and an air source (9); wherein: The shell (1) is provided with an inlet (101), an outlet (102) and an air injection hole (103); The second stirring shaft (5) and the housing (1) are connected via a bearing, the outer wall of the second stirring shaft (5) is provided with a second stirring blade (6), and the second stirring blade (6) is located in the inner cavity of the housing (1); The second stirring shaft (5) is sleeved on the outside of the first stirring shaft (3); the first stirring shaft (3) and the second stirring shaft (5) are connected via a bearing; there is a gap between the first stirring shaft (3) and the second stirring shaft (5); the upper part of the first stirring shaft (3) passes through the top end of the second stirring shaft (5); the lower part of the first stirring shaft (3) passes through the bottom end of the second stirring shaft (5); the lower outer wall of the first stirring shaft (3) is provided with a first stirring blade (4); the first stirring blade (4) is located in the inner cavity of the shell (1); and the lower wall surface of the first stirring shaft (3) is provided with a gas dispersion hole (301); The top of the first stirring shaft (3) and the top of the second stirring shaft (5) are respectively connected to a power source, and the power source drives the first stirring shaft (3) and the second stirring shaft (5) to rotate; the air source (9) is respectively connected to the hollow cavity of the first stirring shaft (3) and the air injection hole (103).

2. The 3D printing nozzle for printing a barrier to contaminated sites according to claim 1, characterized in that: The feed inlet (101) is located on the upper side of the shell (1), and the discharge outlet (102) is located at the bottom of the shell (1); the gas injection holes (103) are through holes, arranged obliquely upward from the outside to the inside of the shell (1); the gas injection holes (103) are arranged in multiple layers along the axial direction of the shell (1); and at least three gas injection holes (103) are provided in each layer of the first gas injection holes.

3. The 3D printing nozzle for printing a barrier to contaminated sites according to claim 2, characterized in that: It also includes a first pressure regulating valve (1031), a connecting valve (1032), a first connecting pipeline (1033), and a second connecting pipeline (1034), wherein: One connecting valve (1032) is provided in each gas injection hole (103); the connecting valves (1032) in the gas injection holes (103) in the same layer are connected via a first connecting pipe (1033); and the first connecting pipes (1033) in different layers are connected via a second connecting pipe (1034); The gas source (9) is connected to the first connecting pipeline (1033) or the second connecting pipeline (1034) via a fourth connecting pipeline, and the first pressure regulating valve (1031) is arranged in the fourth connecting pipeline.

4. The 3D printing nozzle for printing a barrier to contaminated sites according to claim 3, characterized in that: The gas injection hole (103) is provided with a gas injection core assembly, and the gas injection core assembly comprises a fixing member (204), a shell (205), and a spring (201), a sealing sheet (202) and a core body (203) located in the shell (205); the shell (205) is fixed in the inner cavity of the first gas injection hole (1031) through the fixing member (204); one end of the spring (201) is fixedly connected to one end of the shell (205); the other end of the spring (201) is fixedly connected to the sealing sheet (202); the core body (203) is provided with a hollow through hole, and the gas inlet end and the gas outlet end of the core body (203) are both open; the sealing sheet (202) and the gas outlet end of the core body (203) are opposite, and the sealing sheet (202) can block the gas outlet end of the core body (203); the gas inlet end of the core body (203) is connected to the connecting valve (1032).

5. The 3D printing nozzle for printing a barrier to a contaminated site according to claim 1, characterized in that: The power source comprises a motor (111) with a power output shaft (1111), a first gear (112) and a second gear (113); the first gear (112) is fixedly connected to the upper outer wall of the first stirring shaft (3), and the second gear (113) is fixedly connected to the upper outer wall of the second stirring shaft (5); the power output shaft (1111) is respectively adapted to the first gear (112) and the second gear (113), and drives the first gear (112) and the second gear (113) to rotate in opposite directions; It also comprises a third connecting pipe (901) and a second pressure regulating valve (902), the gas source (9) is connected to the hollow cavity of the first stirring shaft (3) through the third connecting pipe (901), and the second pressure regulating valve (902) is arranged in the third connecting pipe (901); It also comprises a first sealing ring (7) and a second sealing ring (8), wherein the first sealing ring (7) is embedded between the first stirring shaft (3) and the second stirring shaft (5) and is located at the bottom of the inner cavity of the second stirring shaft (5); and the second sealing ring (8) is embedded between the second stirring shaft (5) and the housing (1).

6. A method for printing a barrier using the 3D printing nozzle of claim 1, characterized in that: The barrier comprises, from bottom to top, a first bearing layer, a pollution-blocking layer, and a second bearing layer; the method comprises: Step 1: Use a 3D printing nozzle to build the first bearing layer; Step 2: On top of the first bearing layer, a pollution-resistant layer is constructed using a 3D printing nozzle; Step 3: construct a second bearing layer above the anti-fouling layer using a 3D printing nozzle.

7. The method for printing a barrier according to claim 6, characterized in that: The step 1 specifically includes: Step 101, regulating the first pressure regulating valve (1031) to increase the gas pressure so that the gas injection core assembly is in an open state, and the carbon dioxide gas passes through the gas injection core assembly and the gas injection hole (103) and enters the inner cavity of the shell (1); Opening the second pressure regulating valve (902) allows the carbon dioxide gas to pass through the gas dispersion hole (301) located on the first stirring shaft (3) and enter the inner cavity of the shell (1); Step 102, starting the motor (111) to rotate the first stirring shaft (3) and the second stirring shaft (5) in opposite directions; Step 103, the printing material flows into the housing (1) from the feed port (101) of the 3D printing nozzle, and the printing material undergoes a carbonization reaction with the carbon dioxide gas entering the housing (1) from the gas injection hole (103) and the gas dispersion hole (301) under the cutting and stirring of the first stirring shaft (3) and the second stirring shaft (5); after the carbonization reaction is completed, the carbon dioxide gas is continuously introduced into the printing material to produce a first bearing layer printing material; Step 104, move the 3D printing nozzle, discharge the first bearing layer printing material made in step 103 from the discharge port (102) of the 3D printing nozzle, and lay it flat to form the first bearing layer.

8. The method for printing a barrier according to claim 7, characterized in that: The step 2 specifically includes: Step 201, regulating the first pressure regulating valve (1031) to keep the gas injection core assembly in a closed state; Step 202: The printing material flows into the housing (1) from the feed port (101) of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft (3) and the second stirring shaft (5), the printing material reacts with the carbon dioxide entering the housing (1) from the gas dispersion hole (301) to form a pollution-proof layer printing material. Step 203, above the first supporting layer, move the 3D printing nozzle, discharge the anti-fouling layer printing material made in step 202 from the discharge port (102) of the 3D printing nozzle, and spread it on the first supporting layer to form an anti-fouling layer.

9. The method for printing a barrier according to claim 8, characterized in that: The step 3 specifically includes: Step 301, regulating the first pressure regulating valve (1031) to increase the gas pressure so that the gas injection core assembly is in an open state, and the carbon dioxide gas passes through the gas injection core assembly and the gas injection hole (103) and enters the inner cavity of the shell (1); Step 302: The printing material flows into the housing (1) from the feed port (101) of the 3D printing nozzle. Under the cutting and stirring of the first stirring shaft (3) and the second stirring shaft (5), the printing material undergoes a carbonization reaction with the carbon dioxide gas entering the housing (1) from the gas injection hole (103) and the gas dispersion hole (301). After the carbonization reaction is completed, the carbon dioxide gas is continuously introduced into the printing material to produce a second bearing layer printing material. Step 303: Move the 3D printing nozzle above the anti-fouling layer, discharge the second supporting layer printing material prepared in step 302 from the discharge port (102) of the 3D printing nozzle, and spread it on the anti-fouling layer to form the second supporting layer.

10. The method for printing a barrier according to claim 9, characterized in that: In step 101, step 201 and step 301, the pressure p of the carbon dioxide gas entering the inner cavity of the shell (1) after adjustment by the first pressure regulating valve (1031) is equal to the pressure p of the carbon dioxide gas entering the inner cavity of the shell (1) after adjustment by the second pressure regulating valve (902); the carbon dioxide gas pressure p is calculated according to formula (1): p=p0-a×(f-f0)-b×(R-R0) Formula (1) In the formula, p is the carbon dioxide gas pressure adjusted by the first pressure regulating valve (1031), in kPa; p0 is the reference pressure, which is 1000, in kPa; a is the adjustment coefficient related to the physical state of the printing material, in kPa / mm; f is the fluidity of the printing material, in mm; f0 is the reference fluidity of the printing material, in mm; b is the adjustment coefficient related to the motion state of the first stirring shaft, in kPa / rpm; R is the rotation speed of the first stirring shaft (3), in rpm; the rotation speed of the first stirring shaft (3) is the same as the rotation speed of the second stirring shaft (5), and R is the reference rotation speed of the first stirring shaft (3), in rpm; The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve (1031) is equal to the total flow rate of carbon dioxide gas flowing through the second pressure regulating valve (902). The total flow rate of carbon dioxide gas flowing through the first pressure regulating valve (1031) is calculated according to formula (2): Q g =10 3 ×c×Q s +10 3 ×d×A×Q s Formula (2) In the formula, Q g is the total flow rate of carbon dioxide gas flowing through the first pressure regulating valve (1031), in l / min; c is an adjustment coefficient related to the physical characteristics of the printing material, and is a dimensionless variable; Q s The feed speed of the printing material, in m 3 / min; d is the adjustment coefficient related to the chemical characteristics of the printing material, which is a dimensionless variable; A is the alkalinity of the printing material, which is the mass ratio of the alkaline oxide to the acidic oxide in the printing material.

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