Since the promulgation of the "Cleaner Production Promotion Law of the People's Republic of China", our barrel making industry has to implement cleaner production in accordance with the law, improve resource utilization, reduce and avoid the generation of pollutants, and protect and improve the environment. The time is tight and the situation is severe. On the one hand, the state is increasing the enforcement of environmental protection laws and regulations. On the other hand, many of our barrel making enterprises do produce waste gas that has not yet been effectively purified and treated.
Under the present conditions, the installation of waste gas purification and environmental protection equipment by the barrel making enterprises in the drying room is a relatively good solution, but due to the fact that they need to consume more energy and the efficacy of some manufacturers has yet to be verified, many companies have a variety of Concerns and opinions.
Recently, Shanghai Qiaosheng Electromechanical Complete Equipment Co., Ltd. has achieved a major breakthrough in this field. After the use of the WRF-II combustion catalyzed environmental protection furnace used by Shanghai Gaoqiao barrel makers, its environmental protection and energy saving effects have been widely recognized. Experts believe that the equipment can achieve the dual effects of environmental protection and energy saving. This is the best and most successful model for exhaust gas purification and environmental protection equipment (as shown in the figure, it is a schematic diagram of the process of the equipment). Since then, there has been an upsurge of waste gas treatment in the domestic barrel making industry.
Now, I will brief you on some situations in the use of exhaust gas purification equipment at home and abroad in recent years. Before this, I first introduced the technical goal of “4+1†exhaust gas purification and environmental protection equipment proposed by Mr. Yin Yiguo, a metal packaging expert who has conducted in-depth research in this field.
First, exhaust gas purification and environmental protection equipment requirements "4 +1"
The meaning of "4+1" refers to four requirements and one benefit. The specific content is:
Four requirements:
1. The effect of exhaust gas purification reaches the QB-6270-1996 national environmental protection standard in the absence of smoke and odorless.
2. Exhaust gas purification The heat discharged from environmental protection equipment should be recovered and fully utilized.
3. The heat emitted by the environmental protection equipment shall be controlled when used in the drying room. The general accuracy is ±3°C.
4, does not affect product quality.
One benefit:
The operation system of the exhaust gas treatment and environmental protection equipment operating system and the drying room are independent and mutually controllable, which is conducive to the normal operation of the production scheduling and drying room.
II. Introduction to the types and principles of exhaust gas purification and environmental protection equipment
The effective method of purifying exhaust gas in the domestic and international metal packaging industry is the combustion method. Among them are flame combustion (direct combustion), thermal combustion, catalytic combustion and other types. Due to the low concentration of paint exhaust gas in the barrel making industry, it is not possible to purify itself. Therefore, only the latter two combustion methods are generally used.
Thermal combustion (also known as incineration)
It is based on the heat generated by the combustion of the auxiliary fuel (burner) to increase the temperature of the exhaust gas and oxidize the hydrocarbon-containing components in the exhaust gas. The decomposition is transformed into harmless carbon dioxide and water vapor. For the barrel industry, in order to achieve the desired purification effect, it is necessary to design an incinerator that meets the requirements of drying room capacity, baking process, and circulating air volume, that is, to achieve thermal power. “Three T†condition: The reaction temperature in the furnace is about 760° C., and the exhaust gas residence time (Time) at this temperature, and the exhaust gas and oxygen are well mixed (Turbulence) to fully purify the exhaust gas.
Therefore, for different types of drying chambers, different paint types must have a reasonable solution. Although thermal combustion is the most thorough way to clean waste, it is necessary to purify the exhaust gas at a high temperature of 760°C. Only by recycling heat can we consider the practicality and economy of environmental protection equipment.
Catalytic combustion
The use of catalysts in the combustion of exhaust gas accelerates the reaction rate of decomposition of the exhaust gas, so that when the exhaust gas passes through the catalyst layer, only the temperature of 250 to 400° C. is required to purify the exhaust gas, which has significant economical efficiency. Therefore, the catalytic combustion method must be designed for different drying rooms and paints to make high-performance catalyst in the variety, the amount and the catalytic indoor air volume exhaust gas mutual support in order to fully purify the exhaust gas.
The general catalyst composition is divided into three parts: the active component, the cocatalyst and the carrier. The active component is the main body of the catalyst. Without it, the catalytic reaction cannot be completed. The most ideal active components are precious metals such as platinum and palladium, and nickel again. , cobalt and other non-precious metals transition. They have long life, high activity, and do not have the required activity when the cocatalyst alone is present. However, when it coexists with the former, it can increase the activity of the active component. The carrier supports the above catalyst, so that the catalyst has a suitable shape and particle size, has a large specific surface area, is favorable for the reaction, heat transfer and dilution, Extend the life of the catalyst. The carrier may be in the form of a sheet, a honeycomb, a pellet, a column, or the like.
Therefore, the choice and arrangement of catalysts is crucial, but in the process of purifying exhaust gas, the activity of the catalyst is always decreasing with time, namely: we call the catalyst aging or poisoning, because the catalyst is at high temperature The long-term use will cause the growth of crystal grains. The sintering phenomenon will occur and the specific surface area will eventually fail. Therefore, the use of this method to convert the exhaust gas will always result in the replacement of the catalyst.
Third, the combustion method and catalytic combustion method comparison
These two methods are the most concerned and commonly used methods at home and abroad.
Incineration method: simple structure, easy management, and one-hundred burning, is the most thorough method for purifying exhaust gas. It is widely used at home and abroad, but because this method purifies the exhaust gas at a high temperature of 750-800°C, the use of heat is increased. Is the key to technology, otherwise it will lose practical value. At present, domestic incinerators have been able to recycle heat to production for full use.
Catalytic combustion method: Through the catalyst layer, the purification temperature of exhaust gas can be as low as 250 to 400°C, which is more energy-efficient than incineration. However, if there is no heat recovery, the energy consumption of the catalytic converter will, of course, increase the production cost for the barrel maker. At present, there is already a catalytic environmental protection furnace that can fully recover heat. This is a gratifying phenomenon. If the catalyst life can be extended to more than two years, it is more practical. In addition, strengthening the management of catalytic environmental protection furnaces and avoiding catalysts in contact with sulfur, iron and other substances are important measures to extend the life of the catalyst.
Both of the above two combustion methods have one thing in common: they fully utilize the heat emitted by the exhaust gas during the oxidative decomposition to provide the temperature requirements of the combustion chamber. Therefore, a greater concentration of exhaust gas helps to save energy.