Foam producing method, fire extinguishing method, and appliance for foam extinguishing
A foam production method includes mixing liquid nitrogen with a foaming material to produce foam. A gas is produced in situ from liquid nitrogen. As the ratio of the volume of the gas produced by gasification of liquid nitrogen to the volume of the liquid nitrogen is relatively high, when a large gas supply flow is needed to generate a large foam flow, a liquid nitrogen storage device of a small volume can be used instead of bulky air supply devices such as high-pressure gas cylinders, air compressors, air compressor sets and the like, reducing the volume of the air supply device. In addition, the liquid nitrogen used in foaming will release nitrogen gas after the foam blast, such that the nitrogen is also able to inhibit combustion on the surface of burning materials, accelerating the extinguishing of the fire.
1. A method for producing foam for fire extinguishing, comprising mixing a liquefied medium with a foam solution, and applying a disturbance to strengthen contact between the liquefied medium and the foam solution, wherein:
(i) the mixing is carried out in a mixing device, and the applying a disturbance includes arranging a disturbing component;
(ii) the liquefied medium is liquid nitrogen, and a flow of the liquid nitrogen and a flow of the foam solution meet the following equation: Q=mV/nf, wherein Q is a volumetric flow of the liquid nitrogen, m is a preset foaming ratio in a range of 5-200, V is a volumetric flow of the foam solution, n is a volumetric expansion ratio of the liquid nitrogen, and f is a pipeline loss factor in a range of 1-1.4; or
(iii) the mixing is performed under conditions including: mixing temperature in a range of −30° C˜60° C., pressure of the liquefied medium in a range of 1-2 MPa, and pressure of the foam solution in a range of 0.8-1.5 Mpa.
2. The method for producing foam according to claim 1 , wherein:
(i) the mixing device has a mixing cavity, the disturbing component is disposed in the mixing cavity, the mixing cavity has a first inlet, a second inlet, and a first outlet, the foam solution and the liquefied medium are inputted into the mixing cavity via the first inlet and the second inlet respectively, mixed in the mixing cavity, and then gasified to produce foams, and the produced foams are outputted via the first outlet for fire extinguishing; or
(ii) the disturbing component is a conical structure, hemispherical structure, or platform structure.
3. The method for producing foam according to claim 2 , wherein:
(i) the mixing cavity is a cylindrical structure, the first inlet and the second inlet are located at one end of the cylindrical structure, the first outlet is located at the other end of the cylindrical structure, and an angle between a direction of the second inlet and a direction of the first inlet is 0-90°;
(ii) at least one porous structure is arranged in a spaced manner in the mixing cavity; each porous structure has a plurality of pores; the pores in the porous structure face the first inlet, and the porous structure is opposite to a top of the disturbing component and away from the first inlet;
(iii) a cross section of the disturbing component is circular, and a relation between a diameter D7 of the disturbing component and a diameter D2 of the first inlet is: D7/D2=1-4; or
(iv) a distance L between the top of the disturbing component and an outflow opening of the liquefied medium at the second inlet is 0-100 mm.
4. The method for producing foam according to claim 3 , wherein a relation between a diameter D1 of the cylindrical structure and the diameter D2 of the first inlet is: D1/D2=1.1-4; a relation between the diameter D2 of the first inlet and a diameter D3 of the second inlet is: D2/D3=4-10; a relation between the diameter D1 of the cylindrical structure and a diameter D4 of the first outlet is: D1/D4=0.8-2.
5. A method for extinguishing fire, comprising: using the method for producing foam of claim 1 to produce foams, and then outputting the foams for fire extinguishing.
6. A method for producing foam for fire extinguishing, comprising mixing a liquefied medium, water, and a foam concentrate, and applying a disturbance to strengthen contact among the liquefied medium, the foam concentrate, and the water, wherein:
(i) the mixing is carried out in a mixing device, and the applying a disturbance includes arranging a disturbing component;
(ii) a volume ratio of the liquefied medium to the foam concentrate and to the water is 1:1-10:50-300; or
(iii) the mixing is performed under conditions including: mixing temperature in a range of −30° C˜60° C., pressure of the liquefied medium in a range of 1-2 MPa, pressure of the foam concentrate in a range of 0.8-1.5 MPa, and pressure of the water in range of 0.6-1.4 MPa.
7. A method for producing foam for fire extinguishing, comprising mixing a liquefied medium, water, and a foam concentrate, and applying a disturbance to strengthen contact among the liquefied medium, the foam concentrate, and the water, wherein:
(i) the mixing device has a mixing cavity, and the disturbing component is arranged in the mixing cavity, the mixing cavity has a first inlet, a second inlet, a third inlet, and a first outlet; the liquefied medium, water, and the foam concentrate are inputted into the mixing cavity via the first inlet, the second inlet, and the third inlet, respectively, mixed, and gasified to produce foams, and the foams are outputted via the first outlet for fire extinguishing;
(ii) the disturbing component is a conical structure, hemispherical structure, or platform structure.
8. The method for producing foam according to claim 7 , wherein:
(i) the mixing cavity is a cylindrical structure, the first inlet, the second inlet, and the third inlet are arranged at one end of the cylindrical structure, the first outlet is arranged at the other end of the cylindrical structure, a direction of the first inlet, a direction of the second inlet, and a direction of the third inlet form an angle of 0-90° between each other;
(ii) at least one porous structure is arranged in a spaced manner in the mixing cavity; each porous structure has a plurality of pores; the pores in the porous structure face the first inlet, and the porous structure is opposite to a top of the disturbing component and is away from the first inlet;
(iii) a cross section of the disturbing component is circular, and a relation between a diameter D7 of the disturbing component and a diameter D1 of the cylindrical structure is: D1/D7=1.2-4; or
(iv) a distance L between the top of the disturbing component and an outflow opening of the liquefied medium at the first inlet is 0-100 mm.
9. The method for producing foam according to claim 8 , wherein a relation between the diameter D1 of the cylindrical structure and a diameter D4 of the first outlet is: D1/D4=0.8-2; a relation between the diameter D1 of the cylindrical structure and a diameter D3 of the first inlet is D1/D3=20-30; a relation between the diameter D1 of the cylindrical structure and a diameter D5 of the third inlet is: D1/D5=2-6; a relation between a diameter D6 of the second inlet and a diameter D3 of the first inlet is: D6/D3=10-15.