The alcohol burner is an instrument for strengthening the thermal use of the laboratory,flameThe temperature can reach about 1000 ℃, commonly used forGlasswareProcessing of.Common alcoholBlowtorchyesalcoholStorageLampholderSeat blowtorch and alcohol insideStorage tankHanging blowtorch hanging high.When the blowtorch is ignited, first turn down the air regulating rod on the lamp tube, inject alcohol into the preheating plate andlight, make copperLamp tubebe heated;When the alcohol in the tray is almost burned out,nozzleWhen the temperature rises, the alcohol rising from the storage tank will be heated and vaporized in the lamp tube, mixed with the air from the air hole, and the match will ignite the nozzle to produce a high temperature flame.At this time, the adjusting rod can be adjusted to control the size of the flame.After use, the lamp flame can be extinguished by tightening the switch of the hanging blowtorch holder and closing the valve under the alcohol storage tank.Seat type alcohol blowtorch is requiredAsbestos meshcoverSpoutTo extinguish the flame.
Chinese name
Alcohol blowtorch
Foreign name
Alcohol Blast Burner
Classification
Seat type alcohol blowtorch and hanging type alcohol blowtorch
Alcohol blowtorch(Right) is the common heat source in the laboratory.AndAlcohol lampCompared with the temperature it can reach, it can meet the condition of "high temperature".
Advantages and uses
Although the general glass alcohol lamp can be used as a heat source, it is not suitable for some operations with high temperature requirements, such as glasscapillaryThe drawing of.In this case, the alcohol burner can play a better role.
The common apparatus for heating by open fire in the laboratory can be roughly divided into three categories in the table below. Compared with the other two categories, the advantages and disadvantages of alcohol blowtorch can be clearly seen.
heat source
flame temperature
Fuel
General purpose
Advantages and disadvantages
Ordinary alcohol lamp
400~600 ℃, but uncertain, up to 800 ℃
Ethanol, with low concentration requirements
Heating ordinary liquid;Promote general chemical reactions.
Simple operation;However, it is difficult to melt the glass, and the flame will be disturbed by the air flow.Nowadays, most laboratories use electric heaters and magnetic stirrers instead
Bunsen burner
800~900℃
coal gas
Burning solid;High temperature melting crystal;Glassman;Other processes requiring forced heating
The operation is complicated. For the unskilled experimenter, such high temperature is easy to cause danger;The flame is more stable and the firepower can be flexibly adjusted
Alcohol blowtorch
About 1000 ℃
95% ethanol
classification
according toAnhydrous ethanolThe alcohol burner can be divided into seat type and hanging type.Specifically, the fuel of the pedestal alcohol burner is stored in a metal storage tank directly connected with the lamp tube below the lamp tube;Hanging alcohol burnerThe fuel is stored in a tank hanging on the wall.
The following takes the seat type alcohol burner as an example.
All copper blowtorch
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structure
Figure 1 Structure diagram of alcohol burner
The outline structure of the seat type alcohol blowtorch is shown in Figure 1, which is mainly composed of the alcohol inlet（spout）, preheating disk, preheating pipe, nozzle, air conditioning rod, etc.The preheating tube is welded with the nozzle, and a thin tube is connected in the middle to make the evaporated alcohol vapor frominjectorBlow out and burn in the nozzle.Control the size of the flame by adjusting the adjusting rod.
usage method
oneget readyUnscrew the cock for filling alcohol on the pot body, and pass thefunnelPour the alcohol into the kettle body to 2/5~2/3 of the total capacity of the lamp kettle, and it shall not be full or too little.It is easy to be dangerous if it is too full, and if it is too small, the wick will be burnt, affecting the combustion effect.Tighten the cock to prevent air leakage.
be careful:Because the alcohol vapor nozzle in the lamp tube is thin (the diameter of the common model is 0.55mm), it is easy to be blocked by ash particles, so it is difficult to ignite.Therefore, the nozzle shall be checked before each use. If it is found to be blocked, the nozzle shall be punctured with a through needle or a fine steel needle.For a new lamp or a blowtorch that has not been used for a long time, it is necessary to reverse the lamp body 2-3 times before lighting, so that the wick is saturated with alcohol.
twoPreheating and ignitionPut the blowtorch on asbestos board or largeAsbestos meshOn (to prevent the alcohol sprayed during preheating from catching fire), turnAir conditionerSet the air inlet to the minimum.Fill the preheating pan with about 2/3 volume of alcohol and ignite it.When the alcohol in the preheating tube is heated and vaporized and ejected from the nozzle, the flame burning in the preheating disk will ignite the alcohol vapor ejected.Sometimes a match is needed.
3. When the nozzle flame is ignited, adjust it through the air regulating rodIntake volumeMake the flame reach the required temperature.In general, the more air enters,flame temperature The higher.
fourFlameoutWhen not in use, the nozzle mouth can be covered with asbestos mesh or waste wood plate, and the flame can be extinguished generally.Wet cloth can be used for cooling while covering the nozzleLampholderIncrease the air intake to stop the engine.Later, put a cloth (antiScald）Unscrew the cock (copper cap) on the kettle body to release the alcohol vapor in the kettle.
5. After using the blowtorch, the residual alcohol shall be poured out.
working principle
The working principle of the blowtorch can be known according to the above method of use.First, in the preheating diskethanolThe heat generated by combustion heats the ethanol rising along the wick in the preheating tube and vaporizes a large amount of ethanol.Since there is no air in the preheating tube, the ethanol vapor vaporized at high temperature cannot be burned.Therefore, driven by pressure, ethanol vapor is injected into the nozzle from the nozzle, mixed with air in the nozzle, and ignited to start combustion.Due to the thermal conductivity of the burner, once it is ignited, the temperature of the flame at the nozzle mouth is enough to maintain the continuous gasification of ethanol and enter the nozzle through the nozzle.
The flame temperature is largely affected by the mixture in the nozzleAir-fuel ratioImpact.Air-fuel ratioIt refers to the relationship between air andFuel mixtureThe ratio of internal air to fuel.The air regulating rod can adjust the air intake of the alcohol burner nozzle, so as to adjust the air-fuel ratio.The flame temperature can reach an ideal high temperature by increasing the air intake in an appropriate range.
So, both alcohol blowtorch and ordinary alcohol lamp use the gasification and combustion of ethanol vapor as heat source. Why can the temperature of alcohol blowtorch reach higher?The reason is that the alcohol burner uses the lamp tube to enrich the steam and the heat generated by its combustion, and can obtain the maximum combustion and heating efficiency by adjusting the air-fuel ratio.Most of the heat generated by alcohol lamp combustion is dissipated with the convection of the airflow around the flame.Therefore, although the temperature of the alcohol lamp also reaches 800 ℃, the heating is generally much milder.
Precautions and maintenance
1. It is forbidden to use the blowtorch with open welding.
2. It is forbidden to use other heat sources to heat the kettle.When the blowtorch is working, there must be no heat source under the lamp holder,ambient temperatureGenerally, it should be below 35 ℃, and there should be no surroundingcombustible。
3. If the blowtorch still cannot be ignited after twice preheating, it shall be temporarily stopped.Check whether there is air leakage at the interface (can be ignited with a match),Spray outletWhether it is blocked (the probe can be used for dredging) and whether the wick is in good condition (the wick is burnt and should be replaced if it becomes thinner). It can be used only after it is repaired.
4. It must be fully heated before opening the switch and igniting the nozzle gasLamp tubeOtherwise, the alcohol cannot be fully gasified, and liquid alcohol will be ejected from the nozzle, which may form“Fire rain”(especially hanging blowtorch), even causing fire.
5. The continuous use time of the blowtorch should be 30-40 minutes.If the lamp is used for a long time, the temperature of the lamp pot will gradually rise, which will lead to excessive pressure inside the lamp pot, and the blowtorch will be in danger of cracking. The lower end of the blowtorch can be wrapped with a cold wet cloth to reduce the temperature.
6. When the alcohol consumption in the tank is about 20 ml, stop using it. If you need to continue working, turn off the blowtorch and then add alcohol.Do not add alcohol to the tank when the blowtorch is burning, so as not to ignite the alcohol vapor in the tank!
7. If the tank bottom bulges when using the blowtorch, stop using it immediately, and check whether the nozzle is blocked and whether the alcohol overflows.It can be used after the cause is found out and the fault is eliminated.
common problem
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oneBlowtorchThe flame is normal at the beginning of the flame spraying. After the alcohol in the preheating bowl is burned, the flame gradually decreases and finally goes out.
Handling: This is dangerous.First use wetDuster clothCover the pot or sprinkle with cold water to cool the pot.Then check the pot body, and use the probe to dredge the orifice after confirming that it is not damaged.
