Fireproof and explosion-proof of steel drum coating and drying production line

Fireproof and explosion-proof of steel drum coating and drying production line

Xin Qiaojuan

After joining the WTO, China's products are facing global competition. Today, as the number of issues has been resolved, people are increasingly pursuing and relying on high quality products and services. Packaging products are no exception. While giving full play to the functions of packaging and protecting goods, packaging has promoted the sales of products and increased the added value of products. The same is true for steel drums in metal packaging. The development of steel drum packaging enterprises has gradually focused on the appearance quality from the inherent quality of steel drums. Because the structure of the steel drum has been shaped, the curling edge is also optimized, and the intrinsic quality can basically meet the needs of users. However, in order to fundamentally solve the problem of "one type of product, two types of packaging, and three types of price" in China, it is necessary to put the quality of the packaging up, that is to say, while doing a good job of the internal quality of the steel drum itself, The appearance quality of the steel drum is put up. To this end, in recent years, China's steel drum production enterprises have gradually increased the intensity of equipment renovation, and have invested in steel drum coating production lines.

At present, all the steel drum enterprises in the country use a variety of equipment for painting steel drums. The spraying methods include airless painting, electrostatic painting, etc. The equipment is also imported and domestic; the drying equipment has gas (gas) , also have natural gas), fuel, and also far infrared or electric oven drying.

After the steel drum coating and drying production line of steel drum production enterprises is completed and put into production, most enterprises have little knowledge about the safety, fire and explosion prevention of paint, gas, natural gas, etc., so that safety accidents such as fire and explosion occur. Let's talk about the basic requirements and precautions for the safe production of steel drum drying room:

First, the danger of flammable and explosive substances in the paint drying room

The materials used in the coating of steel drums are paints and their thinners, ie solvents. Paints and commonly used solvents (except water-soluble paints and water solvents) are substances that are highly prone to fire. The lower the flash point of the solvent used, the faster the volatilization rate and the easier it is to burn. The vapors volatilized by these solvents during painting can be mixed with the air in the drying chamber at any time to become an explosive gas. If exposed to an open flame, they are prone to explosion and burning hazards. At present, most of the steel drum drying uses gas and fuel oil, all of which are open fires. So how to prevent it? First, we need to understand the flash point, the ignition point, and the spontaneous ignition point.

The degree of combustion of a solvent commonly used in paint is determined by its flash point, self-ignition point, and explosion limit. So, what is the flash point, the ignition point and the spontaneous ignition point?

1. Flash point: The solvent in the paint can be volatilized into steam and run into the air. The temperature rises and the volatilization increases. When a mixture of volatilized vapor and air is capable of flashing a spark in contact with a source of ignition, this brief ignition process is called flashing, and the lowest temperature at which flashing occurs is called a flash point. From a fire point of view, the solvent flash point is the lowest temperature at which the drying chamber may cause a fire. The lower the flash point, the greater the risk of fire.

2. Randian: In the coating and drying production line, whether it is liquid paint and solvent, or gaseous gas and natural gas, it coexists with the air. When it reaches a certain temperature, it will burn when it comes into contact with the fire source. Continue to burn after going to the fire source. At this time, the lowest temperature of the combustible material is called the ignition point, also called the ignition point. Generally, the ignition point of the solvent is higher than the flash point, and the ignition point of the general flammable solvent is 1~5 ° C higher than its flash point.

3. Spontaneous ignition point: Under normal conditions, the general flammable substance and the air will have a slow oxidation process, but the speed is very slow, and the amount of heat is also very small. At the same time, the heat is continuously radiated to the surrounding environment, and the light cannot be emitted like burning. If the temperature rises or other conditions change, the oxidation process will increase, the amount of heat evolved will increase, and it will not accumulate and accumulate, causing the temperature to gradually increase. When a certain temperature is reached, the substance will burn itself, which is spontaneous combustion. The lowest temperature at which the substance is self-igniting due to heat is the point of spontaneous combustion of the substance, also known as the auto-ignition temperature.

At the auto-ignition temperature, the combustible material is in contact with the air and can be burned without the action of an open flame. The self-ignition point is not a fixed number, it mainly depends on the heat generated during oxidation and the outward heat conduction. It can be seen that the same combustible material has different spontaneous ignition points due to different oxidation conditions and different factors.

The phenomenon of spontaneous combustion indicates that the substance is potentially more dangerous than other substances. In general, plant products, oils, coal, and other chemicals are common in substances that cause spontaneous combustion. The following is a table of flammability hazards commonly used for paint thinners in steel drum spraying:

Flammability of common solvents

Solvent name

Flash point (°C)

Spontaneous ignition point (°C)

Explosion limit (% by volume)

Upper limit

Lower limit

benzene

Toluene

Xylene

Ethanol

Butanol

Ethyl acetate

Butyl acetate

turpentine

acetone

Cyclohexanone

gasoline

No. 200 paint solvent oil

-14

5.5

twenty four

7

11

35

-5

18

33.5

20

47

---

33

574

576

531

455

414

343

481

370~410

244

575

450

267

---

9.5

7

7.6

36.5

18

10.2

11.4

15

6.2

13

---

---

6

1.5

1.5

3

5.5

3.3

3.7

2.2

1.7

0.8

2

---

---

1.4

Second, understanding the explosion limit of dangerous goods is an important prerequisite for the fireproof and explosion-proof work of the drying room

Most of the materials in the steel drum spray drying chamber are flammable and explosive materials such as paint, paint solvent, natural gas and gas. When these combustible materials are mixed with air to a certain concentration, an explosion occurs under the action of the ignition source. The lowest concentration of this combustible material that forms an explosive mixture in air is called the lower explosion limit, and the highest concentration is called the upper explosion limit. The concentration can be exploded between the upper and lower explosion limits. This concentration range is called the explosive limit of the substance. For example, the explosion limit of natural gas is 5~15%. That is, natural gas is mixed with air. When its concentration in the air is less than 5%, it is fired to point. This mixture neither burns nor explodes; when the concentration of natural gas in the air reaches 5%, the mixture encounters the ignition source. Mild deflagration; when the concentration of natural gas in the air is slightly higher than 5%, a powerful explosion will occur when exposed to the fire source; when the concentration of natural gas reaches 15%, the explosion phenomenon is similar to the concentration of 5%. When the concentration exceeds 15%, it will not burn or explode if it is in the fire source. Similarly, carbon monoxide incomplete combustion will produce carbon monoxide. The explosion limit of carbon monoxide is 12.5~74.5%. When the concentration of carbon monoxide in the air is less than 12.5%, use fire to remove the point. The mixture does not burn or explode; when the concentration of carbon monoxide in the air reaches 12.5%, the mixture can be slightly deflagrated when the ignition source is in the air; When the concentration of carbon monoxide is slightly higher than 29.5%, a powerful explosion will occur when exposed to a fire source; when the concentration of carbon monoxide reaches 74.5%, the explosion phenomenon is similar to the concentration of 12.5%. When the concentration exceeds 74.5%, it will not burn or explode if it is in a fire source. The table below shows the explosion limits of some gases in the air.

Explosion limit of some gases in the air

name

Upper explosion limit (×10-2)

Lower explosion limit (×10-2)

Carbon monoxide

12.5

74.5

hydrogen

4.1

75

Methane

4.9

15

natural gas

5.0

15

The explosion limit is a very important concept and has great practical significance in fire and explosion protection work:

1. It can be used to assess the risk of combustion and explosion of flammable gases, and can be used as a basis for classifying flammable gases and determining their fire hazard categories. At present, China's flammable gas with a lower explosion limit of less than 10% is classified as a first-grade combustible gas, and its fire risk is classified as Class A.

2. It can be used as a basis for design. For example, to determine the fire resistance of the steel barrel drying room, design the plant ventilation system, etc., it is necessary to know the explosive limit value of the flammable gas present in the place.

3. It can be used as a basis for steel drum enterprises to formulate operational rules for spray drying and safe production. In the place where flammable gas is produced, used and stored, in order to avoid fire and explosion accidents, the concentration of flammable gas should be strictly controlled below the lower explosion limit. In order to ensure this, in the development of safe production practices, appropriate precautions should be taken according to the burning and explosion hazards of flammable gases and other physical and chemical properties, such as ventilation, replacement, inert gas dilution, detection and alarm.

Third, the basic measures for fireproof and explosion-proof of steel drum spray drying room

For steel drum enterprises, fire prevention and explosion prevention safety measures are adopted within the enterprise, generally including technical and organizational management.

(1) Technical measures for fire and explosion prevention

1. Prevent the formation of burning and explosive media. Ventilation is usually used in the spray drying chamber to reduce the concentration of the explosives, so that it does not reach the explosion limit. It is also possible to replace flammable substances with substances that are not burning or difficult to burn. If the outer surface of the steel drum can be cleaned by a cleaning production line, instead of wiping the outer surface of the steel drum with gasoline. This will prevent fire, explosion, and prevent gasoline poisoning. In addition, measures to limit the amount of use and storage of combustibles can be used to prevent the risk of burning or explosion.

2. Prevent the generation of fire sources, so that fires and explosions do not have the conditions for occurrence. In this respect, the following eight sources of ignition should be strictly controlled, namely impact friction, open flame, high temperature surface, spontaneous combustion, adiabatic compression, electric spark, static spark, and light heat ray.

3. Install fireproof and explosion-proof safety devices. Examples include flame arresters, rupture disks, explosion-proof windows, fire dampers, and safety valves to prevent fires and explosions.

(II) Organizational management measures for fire and explosion protection

1. Strengthen the leadership of fire and explosion prevention work.

2. Carry out regular fire safety and explosion safety education and safety inspections to improve people's vigilance and timely discover and rectify hidden dangers.

3. Establish and improve the fire and explosion prevention system and the economic responsibility system for safe fire protection.

4. All access and access to fire-fighting facilities in the workshop and in the spray drying room shall not be occupied or blocked.

5. A voluntary fire protection organization should be established and equipped with a targeted and sufficient number of fire-fighting equipment.

6, strengthen the duty value of the patrol night, strict patrol inspection.

4. Fire and explosion prevention codes that workers in steel drum spraying production should follow

1. It should have a certain knowledge of fire and explosion prevention, and strictly implement the fire and explosion prevention rules and regulations, and prohibit illegal operations.

2. Smoking should be done at designated safe places. It is strictly forbidden to smoke and throw cigarettes in the spray drying room and workshop area.

3, often check the use of natural gas or gas pipelines, fuel lines and electrical equipment is safe and reliable must strictly abide by the safe operating procedures.

4. It is forbidden to use open flames casually in the paint drying room. If it is necessary to use it, it must be reported to the competent authority for approval and safety precautions must be taken.

5. For the electrical facilities used, if it is found that the insulation is damaged, aging, heavy overload and does not meet the fire and explosion protection requirements, it should be stopped and reported to the leader for solution. Do not operate with faults to prevent fires and explosions.

6, should learn to use general fire-fighting tools and equipment, for the fire-proof and explosion-proof tools and equipment in the workshop, should be taken care of, can not be used.

5. Safety requirements for steel drum spray drying room

As the manufacturers use the steel drums to spray and dry, the equipment used is not the same, we will not introduce them one by one. However, as a spray, its equipment has electrical control. Below we focus on the safety, fire and explosion protection requirements of electrical equipment and gas facilities.

(1) Fire and explosion protection requirements for electrical equipment

1. The electrical equipment in the spray drying room must be installed and maintained by a dedicated electrician. Moreover, when installing and repairing electrical equipment, stop burning flammable materials such as paint and thinner to a safe place, and cover with non-combustible materials to avoid fire caused by electric sparks.

2. The electrical equipment and lighting equipment used in the spray drying room must be explosion-proof. For example, the explosion-proof motor should be applied to the exhaust fan. The fan impeller should be non-ferrous metal to prevent the black metal from causing sparks and fire and explosion after collision. Explosion-proof lamps must be used for lighting.

3. Any spraying equipment, such as spray control cabinet, exhaust fan, spray gun, transmission chain (belt), etc., should be installed with an electrostatic grounding device. The grounding resistance should not exceed 10 ohms. Various power transmission knives, switchboards, circuit breakers, etc., are preferably installed outdoors and in a safe place.

4. In electrostatic painting, in order to ensure fire safety, the voltage should not be higher than 80,000 volts, and the distance between the spray gun and the steel drum should not be less than 250mm, so as to avoid the voltage is too high or the spraying distance is too small to cause discharge phenomenon, thus causing electricity. The occurrence of a fire and explosion accident.

(2) Fireproof and explosion-proof requirements for steel drum drying

1. It is strictly forbidden to use the electric drying room with electric resistance wire exposed to bake and spray the steel drum. The steam, hot air and automatic drying line should be used to dry the outer surface of the steel drum. If the far-infrared heating tube is used to bake the steel drum, the far-infrared heating tube should be fixed on the two side walls and the bottom plane of the drying line, and a protective fence should be added on the outside. In case of leakage or steel drum hangs the far-infrared heating tube, it will cause fire and explosion accidents.

2. When baking steel drums, do not rush to place the steel drum in the drying kiln body, in case the vapor of most of the solvent in the freshly sprayed paint is scattered in the steel drum drying kiln, causing a fire explosion accident in case of high temperature.

3. When drying the steel drum in the drying kiln, the induced draft fan must be activated so that the solvent vapor does not accumulate in the drying kiln to reach the explosive limit concentration. If the drafting power in the drying kiln is not large enough, the solvent on the surface of the steel drum can be fully volatilized by extending the leveling time after the steel drum is sprayed.

4. The steel drum drying room should be equipped with ventilation pipes on the roof of the house, and an explosion-proof door, also called an observation door, is installed at an appropriate position on the drying kiln body. It is usually used to observe the situation of steel drum baking. An accident occurred in the dry kiln, which has a pressure relief effect.

5. Strictly control the baking temperature of the steel drum after spraying, so that it should not be higher than the natural point of the solvent in the paint to prevent natural fire or explosion.

In the steel barrel spray drying room, be sure to equip with enough fire equipment, such as foam, dry powder fire extinguishers, dry sand and asbestos board. Fire extinguishers should be placed in accordance with the principle of combining dispersion and concentration. Managers should know the common knowledge of fire prevention, fire fighting knowledge, and be proficient in the use of fire extinguishers; operators should keep in mind that the steel drum spray drying room is a flammable and explosive area, must have knowledge of fire prevention and fire fighting, and will be proficient in using fire extinguishers and simple fire equipment. . In the event of a fire, immediately turn off all power switches (workshop main switch) and immediately extinguish the fire. If necessary, you should first report to the relevant department to cooperate with the fire.

Safe and civilized production has become the top priority for steel drum manufacturers today. The fireproof and explosion-proof work of steel drum spray drying room should attract enough attention from relevant personnel. According to relevant personnel in the industry, every year, 3 to 5 drying lines in steel drum production enterprises have fire or explosion accidents, and the economic losses caused by this are quite severe. In today's steel price hikes, steel drum enterprises are in a meager profit or even in the case of capital preservation, the fireproof explosion-proof and safe and civilized production work of steel drum spray drying line will have far-reaching significance for the development of steel drum enterprises.

Cheese Tools

Cheese Tools,Cheese Spreaders,Cheese Spreader Knife,Cheese Tool Set

Liveon Industrial Co.,Ltd. , https://www.kitchenknifes.de