Singeing machine – gas singeing machine
The gas singeing machine is composed of main parts such as cloth feeding device, bristle box, singeing device, fire extinguishing and cloth dropping device, as shown in Figure 6-1. It is a widely used gas singeing machine at present. It has a simple structure, easy operation, abundant fuel sources, low labor intensity and high production efficiency.
1. Fabric feeding device
Its function is to make the fabric enter the machine and frame at a certain position flat and wrinkle-free It is equipped with cloth guide wooden strips or cloth guide tubes, cloth tensioner, edge suction device, cloth guide roller, etc. Due to the high speed of the singeing machine, in order to avoid fabric wrinkles, the height and length of the fabric feeding device should be appropriately increased to increase the warp tension of the fabric.
2. Brushing box
The bristle box is equipped with multiple brushing rollers to brush away impurities such as short fibers, short spun yarns and dust attached to the surface of the fabric, and to straighten the loose short fibers on the surface of the fabric. , to facilitate singeing.
Most of the bristle boxes are stationary, with 4 to 8 bristle rollers installed in the box, and the fabric runs from bottom to top between two rows of vertically arranged bristle rollers. The multiple bristle rollers in contact with the fabric rotate at high speed in the opposite direction to the fabric’s running direction to brush the bristle. Brushing rollers include bristle rollers, nylon rollers or bread sand rollers. In addition, 1 to 2 pairs of emery rollers and 1 to 2 scrapers can be added to remove impurities such as cottonseed husks.
In addition to the brushing efficiency being related to the shape, density, bristle characteristics of the brushing roller, the number of rollers and the relative speed between the roller surface and the fabric, the degree of contact between the roller and the fabric is also an extremely important factor. Therefore, an adjustment mechanism is provided to adjust the position of the bristle roller.
Some singeing machines use polygonal bristle rollers, which can vibrate the cloth surface when rotating, helping to improve the bristle effect.
In order to prevent the lint, dust and impurities brushed by the upper roller from being brushed to the lower roller, a dust shield should be separated between the upper and lower adjacent rollers to prevent the lint from falling into the dust box, and a pipe with an exhaust fan connected below. It is sucked and discharged into the dust removal box and discharged regularly to improve the working environment and safe production conditions in the workshop.
3. Singeing device
(1) Fire port: The fire port is the main component of the gas singeing machine, which directly affects the effect and efficiency of singeing. An excellent burner should have a high and uniform combustion temperature, a large jet velocity of the flame on the surface of the fabric, and should not deform when encountering sudden cooling and heating. It should also have a simple structure, be easy to repair, and save fuel.
There are many types of flame outlets, including flame type, radiation and flame mixed type, complete combustion flame type, flameless type, etc. There are flame burners and slit burners and porous burners. Among them, the slit burner is widely used.
① Flame-type burner: The slit-type burner is a narrow and long box made of cast iron. Its cross-sectional shape is shown in Figure 6-2. Inside the box is a mixing chamber for flammable gas and air. There is a slit in the upper part of the small box, which is the mixed gas combustion port. The length of the slit is basically the same as the length of the fire port. In order not to waste flammable gas, the amplitude of the flame jet can be adjusted by pressure plates or high-pressure air at both ends to adapt the flame jet width to the width of the singeing fabric.
The slit width of the fire port is slightly different according to the type of flammable gas used, and can be adjusted according to different situations. For combustible gases that burn quickly, such as city gas, water gas, etc., the slits should be smaller, usually 0.5 to 0.8mm; for those with slow burning speeds, such as propane, butane, etc., the slits should be larger, usually 1 ~2mm. The quality of singeing depends on the level and uniformity of the singeing temperature, and has nothing to do with the length of the singeing time. Gas singeing machines are generally equipped with 2 to 6 burners.
This kind of fire port has a simple structure and has been widely adopted. However, because it is made of cast iron, the burner is easily deformed and blocked after long-term use, resulting in uneven slits and uneven flames. The flame temperature is also prone to fluctuations due to changes in gas pressure, resulting in greater heat energy loss and affecting the quality of singeing. . Therefore, this kind of fire vent has been gradually eliminated.
Figure 6-3 shows the porous burner, which is a singeing burner improved from the slit burner. The width of the burner gap is 5~6mm, and a stainless steel porous plate or ceramic porous plate with consistent and evenly distributed holes is installed in the burner. The flame is ejected from the orifice plate, wide, short and uniform. In addition, the thermal stability of stainless steel orifice plates and ceramic orifice plates is better, and the stability of the flame is also better. However, the flame of this kind of burner is not easy to connect into one piece, and it is easy to produce uneven singeing. It is only suitable for singeing of thin fabrics.
The above two flame-type burners mainly rely on the flame sprayed onto the surface of the fabric to singe, and the thermal efficiency is relatively low.
② Radiation and flame mixed burner: Figure 6-4 shows the radiant burner. It is installed with special-shaped refractory bricks on the fire mouth made of cast iron. When the flame is sprayed from the fire port to the surface of the fabric for singeing, the fabric has a certain reflection effect on the flame and the hot air driven by it, so that the flame and hot air are reflected on the special-shaped refractory bricks to continue burning, and the refractory material generates thermal radiation. . In this way, the singeing temperature and the uniformity of the flame are improved, and the contact surface between the cloth surface and the flame is increased, thereby improving the thermal efficiency and speeding up the vehicle speed.
③ Complete combustion flame burner: Figure 6-5 shows complete combustion Flame type burner. Close view of cast iron burner bodyAt the mouth, there are two cold water channels for cooling, which are used to reduce the temperature of the burner body. There are two mixing chambers inside the burner. Above the second mixing chamber, multiple layers of stainless steel laminations are installed, forming small square holes between each other. Above are two refractory bricks (mainly made of silicon carbide and corundum bonded and sintered) that can withstand sudden cooling and sudden heating. into) the combustion chamber and the burner.
The mixed gas enters the mixing chamber, undergoes a secondary expansion, and then shrinks through the oblique hole, then enters the second mixing chamber, undergoes a second expansion, enters the fine square hole, shrinks again, so that the mixed gas is fully mixed, and then injected into the combustion chamber combustion. The hot refractory bricks accelerate the combustion speed of the mixture and make it burn completely. The combustion temperature can reach 1260℃. Although some flames still erupt from this kind of burner, the heat is fully utilized, the burner is not easily deformed, the flame stability is good, and the singeing efficiency is high.
④ Flameless burner: Figure 6-6 shows a double-jet flameless burner. The mixed gas expands after entering the mixing chamber, and then is suddenly blocked and contracts at the slit, converting the energy into the mixing energy of the gas for further mixing. Then, it enters the second mixing chamber to fully expand, and the impurities are filtered by the metal mesh. After being blocked and contracted again at the second slit, it is injected into the combustion chamber through two inclined slits. Due to the fast injection speed, a certain vortex is formed, which increases the mixing degree of the mixture. After it is pre-combusted in the second combustion chamber, almost no flame is ejected from the burner. In this way, the heat energy consumption is less, the temperature is high, and the singeing effect is good, which is very suitable for singeing of chemical fiber fabrics.
In recent years, the burner has developed towards computer control. It can be controlled by using the flame intensity, cloth surface temperature, vehicle speed and the relationship between the burner and the fabric. The automatic control program compiled from four parameters such as distance can automatically control the flame intensity. The flame port can be rotated to produce different singeing positions, which can produce three effects: weak burning, medium burning and strong burning. As shown in Figure 6-7.
(2) Gas mixing device: The structure of the gas mixer is shown in Figure 6-8. Combustible gas and air can only be completely burned at an appropriate mixing ratio, thereby obtaining a higher temperature. Since the diameter of the air inlet pipe is large and the diameter of the outlet pipe is small, a very high air flow is formed at the outlet, and negative pressure appears in the space around it, sucking the gas into the diffuser tube in proportion. The diameter of the diffusion tube gradually increases, and the flow rate of the mixed gas gradually decreases, giving the mixed gas a certain diffusion and mixing time and improving the mixing degree.
(3) Gasoline gasifier: The flammable gases used in gas singeing machines
mainly include coal gas, petroleum gas and There are three types of gasoline gas.
The gas generator is a device for producing generator gas, water gas and semi-water gas. According to different structures, there are mechanical generators, ladder generators, furnace shaft rotating generators and two-stage generators; according to different processes, there are fixed ( It is a general furnace, using coal as raw material) and fluid bed (such as boiling furnace, using pulverized coal as raw material), etc. Generally, the furnace body of a gas generator is cylindrical, with an outer shell made of steel plates or bricks, lined with refractory bricks, and equipped with feeding and ash discharge equipment, blast ducts, gas ducts, etc. The gasification process is a thermochemical reaction process in which the carbon in the fuel interacts with oxygen and water vapor in the air. At the same time, the carbonization and drying process of coal is also carried out. The calorific value of gasification gas is low, about 4.18×106～12.5×106 J/m3 .
Petroleum gas comes from C1 ~ C4 hydrocarbons in petroleum Mixture; the liquefied petroleum gas used for singeing contains 50% propane and 50% butane, with a high calorific value of 11.3×107～10.4×107J /m3.
Considering the source of gas and convenience of operation, gasoline vaporizers are currently relatively used. The gasoline vaporizer can quickly vaporize liquid gasoline into flammable gas for use in the singeing machine. Its structure is shown in Figure 6-9. The carburetor allows the gasoline to enter the internal and external rotor oil pump through the oil filter, and controls the required amount of oil through the flow meter. After the gasoline is sent to the atomizing nozzle at the top of the gasifier, the gasoline is sprayed down in the form of mist, and most of the mist gasoline is vaporized on the surface of the tube heater. The air is sent to the lower part of the gasifier and heated by the fin heater. The temperature is above 70~80℃. The air and gasoline are mixed at a ratio of (30~80):1 and passed through the gas-water separator at the top of the gasifier. Send to singeing machine. The unvaporized oil droplets return to the tube heater to continue being heated and vaporized.
4. Fire extinguishing and cloth dropping device
After the fabric is singed, the surface temperature of the fabric will be high and may even be stained with sparks. If the fabric is not extinguished and the temperature of the fabric is not lowered in time, it will cause damage to the fabric and even cause a fire. Therefore, the fabric should be passed through the fire extinguishing device immediately after singeing to extinguish sparks and reduce the cloth temperature. There are roughly two types of fire extinguishing devices: one is a steam fire extinguishing tank, in which the singeed fabric is extinguished by steam spray, which is suitable for dry falling cloth; the other is a dipping tank for fire extinguishing, in which the singed fabric is immersed in hot water. Or a fire extinguishing tank for desizing liquid (light alkali or enzyme liquid) to achieve the purpose of fire extinguishing and initial desizing. Currently, most printing and dyeing factories adopt this device.
Fabrics that are rope-shaped after singeing are continued to be sorted after the fabric comes out of the dipping (fire extinguishing) tank and is formed into a rope through the cloth guide magnetic coil.
Fabrics that are flat-width finished after singeing will be flattened by the reciprocating swing of the cloth drop frame after the fabric comes out of the fire extinguishing chute.The sheets are stacked in cloth boxes.
In order to reduce the labor intensity of operating the singeing machine and avoid burning the fabric due to sudden shutdown due to electrical or mechanical failure during operation, automatic ignition, automatic fire extinguishing when the fire is stopped, automatic flipping of the fire, backfire explosion prevention and automatic adjustment of gas mixture are now adopted Automation measures such as proportions.
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