Cause analysis and preliminary solution of fire in powder spraying vertical line curing furnace

Powder debut

This article introduces the phenomenon of fire in the production process of the powder spraying vertical line curing furnace, and analyzes the cause of the fire through the phenomenon

The method of controlling the production of fluff in the curing furnace is explained, and it is proposed that reducing the exposure of volatile gas to cold air is an effective method to reduce the production of fluff in the curing furnace

Through the transformation of the top of the curing furnace, the gas containing volatiles in the curing furnace can be reduced to enter the furnace top insulation cotton, and flammable crystalline particle coatings are produced

In recent years, the fire in the spraying vertical line curing furnace has been plagued by the manufacturers of the existing vertical line curing furnace

Therefore, all manufacturers with vertical line spraying equipment are busy cleaning the curing furnace.

Analysis of the cause of the fire

Polyester resin is a polymer material.

The lint will adhere to all corners of the curing furnace, the furnace wall, the furnace duct, the air curtain and the air duct, and the fan blades.

Every time you clean, you must draw out the air curtain fan, the air curtain channel, the entrance and exit of the curing furnace, the chain, the polishing fan blade, and the entrance and exit of the curing furnace.
Each cleaning takes 4 or 5 hours, 4-5 times a month, because everyone is suspicious of curing The flock in the furnace encounters static electricity which is the main cause of fire
.

※Note: The gas containing resin component will eventually form fluff when it meets the cold air, so how to reduce the chance of the gas in the furnace encountering the cold air is a breakthrough point
.

Increasing the air volume in the air curtain area can effectively reduce the hot air overflow in the curing furnace and ensure the heat loss in the curing furnace
.
Doing so can not only reduce the flock produced by the gas containing resin, but also reduce the consumption of natural gas.
Once this practice is implemented, the benefits will be huge
.

The lint is attached to every corner of the curing furnace.
The most important thing is that the gas that forms the lint will enter the insulation layer on the top of the furnace.
What is formed in the insulation layer is not lint, but attached to the rock wool.
Very sparse crystals
.

It takes about a year for such crystals to gather into dense yellow crystals, because the rock wool in the new solidification furnace is still tightly filled
.

These yellow crystals are only distributed in a part of the heat insulation layer, but as time goes by, the rock wool in the heat insulation layer will become loose if you step on the furnace roof more times (it is recommended to build walking on the furnace roof and clean the furnace.
Channel)
.

At the same time, the yellow crystals will spread more and more to the bottom of the insulation layer, and the rock wool in the insulation layer will gradually darken in color
.

Experiments have proved that the darkened rock wool is combustible, and the yellow crystals are also very easy to burn
.
In an experiment in 2012, it was found that the ignition point of the yellow crystals was even lower than 200°C.
Therefore, the yellow crystals in the thermal insulation layer of the furnace roof are also a source of fire hazard
.

(Note) At the end of each year, most spraying companies will carry out a thorough cleaning of their equipment, and the outside of the curing furnace is no exception
.

Therefore, whenever you see oily matter precipitated outside the curing furnace, you must pay attention to check whether the rock wool on the top of our curing furnace has reached the dangerous period.
This is also a reminder of the equipment; the danger is coming soon
.

See below:

The appearance of the curing furnace indicates that a large amount of volatile substances have been precipitated in our curing furnace recently, and it is also time to check the rock wool on the top of the curing furnace
.
The new curing furnace will not have these objects precipitated, and the curing furnace with a short use time will not appear this phenomenon
.

The above two points are the analysis of the possible causes of the fire.
The third point is the hint that the fire may occur.
For this situation, if the hidden dangers found are completely blocked and eradicated, the vertical line curing furnace can be avoided
.

Introduction to the fire scene

The location of the fire is the inlet first, followed by the outlet
.

After the entrance and exit of the curing furnace burned for a period of time, the position of the furnace top air curtain machine began to smoke
.

In fact, the fire point is generally where the chain enters and exits the curing zone
.
(Because the curing zone is temperature-constant and will not produce lint, the fire point will not be in the curing zone, but only at the connection part between the air curtain zone and the curing zone where the temperature is unstable, that is, the marked position and its vicinity)

Another place that is often overlooked is the exhaust fan on the top of the furnace.
When a fire occurs, people often pay attention to the situation in the furnace.
If the fire at the inlet and outlet has not been extinguished by a quilt, almost no one will pay attention to the top of the furnace.
The exhaust fan on the roof
.

In fact, the exhaust fan at the moment of the fire happened to play a role in fueling the flames.
Because a large amount of heat in the furnace needs to be discharged, the exhaust vent is just the best outlet
.

In the exhaust pipe on the exhaust fan for a long time, there will be a large amount of floc accumulation in the exhaust pipe, and it is easier to burn, so if the top of the workshop is a flammable structure, it is very easy to cause a large area of ​​fire
.

In recent years, some technicians have proposed to remove this fan, but there has been controversy
.
However, the equipment of some domestic enterprises does not have this exhaust fan, and there has been no fire
.

Concluding remarks

Through the analysis of the two aspects that may cause the fire, and the introduction of the fire scene, we can easily draw the conclusion that the flocs in the furnace should be removed in time, the insulation layer of the furnace roof should be replaced regularly, or the insulation should be used.
A better and denser insulation material fills the insulation layer
.

Pay more attention to the condition of the outer wall of the curing furnace, and deal with the problem in time.
Paying attention to these points can basically completely block the source of the fire, and ensure that the vertical line curing furnace will not catch fire again
.

It is generally recommended to replace the thermal insulation cotton on the roof of the furnace every year from April to May.
If the temperature of the furnace roof is very high during June to September, the construction efficiency will be greatly reduced and the construction quality will also be affected
.