Talking about the heatstroke prevention and cooling of steel drum painting and drying line

Talking about the heatstroke prevention and cooling of steel drum painting and drying line

Yang Wenliang Xin Qiaojuan

In the production process of steel drums, the drying oven is always accompanied. The surface treatment before the steel drum is painted, it must be dried after moisture drying; the curing of the paint film after painting needs to be dried; some of the front surface treatment process also has the treatment liquid heating process, and the painting also has the paint heating process. . Therefore, the drying and heating process is crucial in the production of barrels. However, most of our barrel-making enterprises only pay attention to production, and do not pay attention to the heatstroke prevention and cooling of the drying line, which not only affects the health of the operators, but also is not conducive to production safety and quality assurance.

First, the high temperature environment of the drying furnace harms the human health

People must maintain a certain body temperature, because the increase in body temperature will accelerate the chemical reaction in the body, and the body's metabolism will be impeded.

The body's substances are continuously oxidized, and heat is generated continuously. The heat and heat balance are balanced, and the human body temperature can be kept within a certain range. The mechanism by which the body regulates body temperature can be divided into chemical and physical. Chemical body temperature regulation is achieved through the physiological process of the nerve-body fluid system. When the outside temperature is low, the heat production is enhanced, and when the outside temperature is high, the heat production is weakened. Physical temperature regulation is the exchange of heat between the body through physical methods such as convection, radiation, and evaporation. In a high temperature environment, the regulation of body temperature mainly depends on the physical regulation mechanism.

Convection, radiation and evaporation through the surface of the skin are the main ways of heat dissipation. In addition, a part of the heat is emitted through the lungs and respiratory tract, and generally does not exceed 3%.

The surface of the human body is constantly drained of water, and these waters carry away heat when they evaporate. At normal temperature, evaporative heat dissipation accounts for only about 1/4 of the total body mass. However, when the temperature is higher than the human skin temperature and there is an external radiant heat source, the human body almost completely relies on the evaporation of sweat to dissipate heat. The amount of heat dissipated is related to the temperature and relative humidity of the air and the speed of the airflow. There are different maximum possible evaporations under different climatic conditions. If the amount of sweating is greater than this limit, it is ineffective for evaporative heat dissipation. In the high temperature environment, physical exertion often causes sweating and cannot all evaporate.

The human body must maintain a constant thermal balance. If the human body generates heat and absorbs external heat more than the amount of heat dissipation, it is in a state of heat storage, thereby raising the body temperature. At different temperatures, physical activity of different strengths, body temperature will have different degrees and increase; at high temperatures, due to the combined effects of temperature and labor intensity, the body adapts to this environment and labor intensity, certain physiological functions appear A certain degree and change should be considered normal. If the stored heat exceeds a certain limit, it may cause the body temperature regulation function to be out of regulation and cause overheating or heatstroke.

The symptoms that occur in the high temperature environment of the drum drying line are mainly heat sickness and enthusiasm.

The main manifestation of heat-induced disease is a significant increase in body temperature, sometimes above 40 °C. During the onset of the disease, the patient first has some prodromal symptoms, such as dizziness, headache, thirst, nausea, etc.; when the condition is severe, the body temperature rises remarkably, the pulse is fast and weak, the complexion is flushed, the breathing is rapid, and the subjective symptoms are more obvious; There was a coma. If the rescue is not timely, it can be life-threatening due to heart and respiratory failure.

The enthusiasm is caused by excessive sweating in the high temperature environment and loss of excessive salt, resulting in low sodium and low potassium in the blood. In the light, there is a calf muscle spasm, a severe muscle pain in the limbs, and finally a muscle spasm. In general, patients with enthusiasm, as long as the salt water is added in time, the symptoms can quickly disappear.

High temperatures can also cause indigestion, affect liver function, and cause respiratory infections and neurological diseases.

Second, the basic measures for heat insulation and cooling of steel drum drying room

When the radiant heat and convective heat on the surface of the drying furnace significantly affect workers, insulation measures should be taken as much as possible. After the insulation measures are taken, the outer surface temperature should not exceed 60 ° C, preferably below 40 ° C.

The heat insulation method of the drum drying furnace is mostly of the thermal insulation type. Thermal insulation is to coat the surface of the furnace with a layer of poor thermal conductivity to reduce the heat released from the furnace. The worse the thermal conductivity of the material, the greater the thickness, the more heat dissipation in the furnace is reduced. Thermal insulation methods generally include wrapping, painting and filling. In the package, the heat-generating furnace body is wrapped with a heat insulating material such as a plate or a fiber. The smear is a powdery thermal insulation material which is soluble in water and added with water to form a paste, which is directly coated on the surface of the furnace body. Filling is the filling of the insulating material into the additional casing of the furnace body. Among them, the wrapping method is the most widely used. When selecting a thermal insulation material, attention should be paid to the high temperature resistance of the material. Some thermal insulation materials have poor heat resistance, such as cork board, sugar cane board, wood fiberboard, etc., which can only withstand 100~120 °C, and are not suitable for steel drum drying furnace. Some insulation materials have high temperature resistance, such as asbestos, slag cotton, diatomaceous earth, etc., can withstand temperatures of 600 ~ 800 ° C. The use of thermal insulation materials should be protected from moisture, because the thermal insulation properties of the materials will be reduced after moisture absorption, and some materials will be loosened due to excessive water absorption.

Third, the steel barrel painting and drying workshop natural ventilation cooling measures

The air in the paint shop is temperature-resistant due to the heating of the oven. If you can continuously replace the higher temperature air in the workshop with the lower temperature air, and discharge the hot air in the workshop, you can cool down. Excluding hot air and sending in cold air can be done by mechanical means, or by natural force. The former is called mechanical ventilation, and the latter is called natural ventilation.

Natural ventilation is caused by hot pressing or wind pressure. The hot pressing action is the gravity action of cold air and hot air. When the indoor air is heated to a higher temperature, it becomes lighter than the air with a lower outdoor temperature. As a result, the lighter hot air in the room rises upwards and is discharged from the upper opening of the workshop, while the heavier outdoor cold air is The orifice in the lower part of the workshop flows in, thus forming a hot-pressed natural ventilation. The effect of wind pressure is that when the outside wind blows to the factory, a positive pressure greater than atmospheric pressure will be generated on the windward side of the plant, and a negative pressure less than atmospheric pressure will be generated on the leeward side of the plant, due to the two aspects of air. The pressure difference, the air outside the factory enters the factory from the opening on the windward side wall, and the air in the factory is discharged from the hole on the back wall, thus forming a natural air circulation. In fact, hot pressing and wind pressure act simultaneously, but since the outdoor wind speed and wind direction often change, the wind pressure changes greatly, while the hot pressing changes little.

In order to achieve good natural results, design calculations should be made in advance to determine the amount of ventilation required to remove the waste heat from the workshop, and determine the area of ​​the air inlet and exhaust vents of the plant according to the necessary ventilation, as well as the type of inlet and exhaust windows. Do you want to install a windshield? However, natural conditions often have large fluctuations. Therefore, it is necessary to make necessary adjustments to natural ventilation as the weather conditions change. This adjustment is to use the opening and closing of the skylight and side windows of the factory to properly organize the airflow, so that the outdoor air entering the workshop is blown to the working area first, or the hot air in the workshop can be smoothly discharged. If the temperature in the workshop increases, the amount of natural ventilation can be increased by increasing the area of ​​the intake and exhaust windows.

Natural ventilation does not require external power, so it is more economical than mechanical ventilation, and natural ventilation produces a large amount of ventilation. Therefore, it is a common ventilation method used in general steel drum coating and drying workshops.

Fourth, steel drum painting drying line mechanical air supply cooling measures

In the steel drum painting and drying workshop, in order to increase the air velocity at a local location, or to send cold air directly to the work site, a local mechanical air supply method is often used. Such measures can be divided into three types: dry air, spray air and wet air. In general, in order to dry the effect of the paint film, it is required to dry as much as possible in the drying chamber. Therefore, for most parts of China, the cooling method of sending dry air is often adopted.

Sending dry air means sending untreated air to the working place with a fan. The purpose is to generate a large wind speed at the working place to promote the evaporation and heat dissipation of the human body. The body heat dissipation mainly has three ways of convection, radiation and evaporation. When the temperature of the air and the surface temperature of the equipment, walls, etc. around the human body are higher than the temperature of the human skin, only the evaporation of the sweat is used to dissipate heat, and the speed of evaporation of the sweat is related to the wind speed, so that the dry air can accelerate the air flow speed. Cooling. Fans that send dry air are generally placed near the work site without air ducts. There is also a low-temperature tunnel wind sent to the workshop to cool down.

5. Health care and organizational measures for heat treatment and cooling of steel drum drying line

Health measures for heatstroke prevention and cooling, including health checkups, supply of refreshing drinks, and health and high temperature work lounges.

For workers who work at high temperatures, they should undergo a health check before employment and before entering the summer. All heart, lung, vascular organic diseases, persistent hypertension, stomach and duodenal ulcers, active tuberculosis, liver disease, kidney Patients with diseases, obesity, anemia and acute infectious diseases, and debilitating central nervous system diseases are not suitable for high temperature operation.

High temperature workers sweat a lot. In the hot season, a worker can sweat 8 to 10 liters in an eight-hour working day, sometimes reaching 12 liters, and the salt lost with sweat is about 40 grams. A large loss of water and salt, if not compensated in time, may lead to fatigue, weakness, loss of appetite, indigestion, and even enthusiasm. Therefore, it is necessary to supply a salt-containing refreshing drink to supplement the loss of water and salt, and to relieve the thirst.

The high temperature operation workshop shall set up a workshop lounge. The lounge shall be located in the work area or not far from the work place, and shall be insulated from the effects of high temperature and radiant heat. The room shall be well ventilated and the temperature shall be kept at 30. Below °C. The high-temperature workers will use a short break during the break to quickly dissipate the accumulated heat in the body and restore the physiological functions of the cardiovascular system.

The organizational measures for heatstroke prevention and cooling include establishing an appropriate labor break system, arranging the life of high-temperature workers, and conducting publicity and education.

In order to avoid overheating of workers in high-temperature workers, the time for continuous labor should be shortened, the number of alternating labor and rest should be increased, or the working hours should be adjusted appropriately, such as working in the morning and evening, and resting at noon. For high-temperature workers, it should also be noted that workers are guaranteed to be fully rested after work. For high-temperature workers and their families and related cadres, it is necessary to strengthen publicity and education on heatstroke prevention and heatstroke prevention.

In fact, the heatstroke prevention and cooling of the steel drum drying room is not only good for the operators, but also has a great guarantee for the quality of the products and the safety of production. Especially in the summer, when the temperature in the drying chamber is high, it is not conducive to the drying of the steel drum paint film. When the indoor ventilation is unfavorable, the organic solvent is difficult to volatilize and discharge in time. The vapor of the organic solvent accumulates indoors, which not only affects the workers. The body is healthy, and it is prone to accidents such as burning and explosion. Therefore, the heatstroke prevention and cooling of the steel drum drying room is of great significance.