Microwave application in the chemical industry 1. Characteristics of microwave:
1. Straightness: Straight line propagation similar to visible light.
2. Reflectivity: It is reflected when it encounters a conductor such as a metal object. Like the mirror reflects light waves, the metal does not absorb microwaves.
3. Absorbability: It is easily absorbed by polar molecules (such as water) to convert into heat.
4. Penetration: Microwaves are not absorbed by non-polar molecules (insulators such as ceramics, polypropylene, etc.) and do not generate heat but can penetrate these objects.
Second, the application of microwave in the chemical industry:
1. Microwave research in the chemical industry is a new frontier interdisciplinary subject. The application of microwave in chemical products not only saves a lot of energy, but also can complete several processes of some products in one time in microwave equipment. Many organic compounds do not directly absorb microwaves significantly, but they can use a "sensitizer" that strongly absorbs microwaves to transmit microwave energy to these substances to induce chemical reactions. Microwaves induce the action through the catalyst or its carrier, ie, consumed. Microwave energy is used to induce the occurrence of a catalytic reaction, which is called a microwave induced catalytic reaction. The microwave muffle furnace can be used to melt and ash samples, and put some tgsin materials (usually sic) with high absorption microwave around the sample container. These materials can absorb microwaves 100%, so that the temperature will be in a short time. Elevated (up to 1000 °C in 2 min); compared to conventional muffle furnaces, the melting and ashing of microwave muffle furnaces is faster and less energy-intensive, and is used when placing and removing samples. Thermal radiation can also be avoided.
2, microwave chemical equipment main application objects are: glass fiber, chemical raw materials, starch cobalt oxalate, cellulose (such as hydroxyethyl cellulose, carboxymethyl cellulose, etc.), mannitol, nickel hydroxide, lithium cobalt oxide, graphite , carbon brush, silicon carbide, calcium chloride dihydrate, activated carbon, zirconium oxychloride, zirconium oxide, zirconium hydroxide, zirconium carbonate, zirconium orthosulfate, ammonium zirconium carbonate, zirconium silicate, potassium zirconium carbonate, oily ink Dry agent, water-based ink cross-linking water-repellent agent, expandable graphite, various ceramic zirconia, nano-iron oxide, positive temperature coefficient (PTC) heat-sensitive ceramic components and honeycomb PTC components.
Third, the advantages of microwave equipment:
Microwave heating is quite different from traditional heating methods. Traditional heating methods rely on heat sources to heat the surface of the object through radiation, conduction, convection, etc., and then heat the internal temperature. Gradually increase. The heat transfer in most objects is very slow, such as rubber materials, so it takes a long time to reach the overall heating of the object. At the same time, it is easy to cause the unevenness of heating of the object, affecting the quality of the heated object, and even changing the color, nutrient composition and physical and chemical properties of the heated object, while the microwave heating has a unique heating method - the overall heating of the material.
Therefore microwave heating has the following advantages:
1, penetrating heating, heating speed, uniform heating. The distance it penetrates is theoretically in the same order of magnitude as the wavelength of the electromagnetic wave. Therefore, the macroscopic performance is that the heating speed is fast, the uniformity is good, the color of the object is kept, and the composition remains unchanged. Microwave heating is a process in which the object to be heated becomes a heat generating object, which is called an integral heating method, and does not require heat conduction, so that uniform heating can be achieved in a short time. Regardless of the shape of the various parts of the object during microwave heating, electromagnetic waves are generally uniformly infiltrated to generate heat, so that the ineffectiveness of heating of the dielectric material is greatly improved. Compared with high-frequency heating, microwave heating does not require the design of an electrode of a suitable shape, and uniform heating can be achieved regardless of the initial object, which is advantageous for improving product quality.
2, selective heating, energy saving and efficient. Microwave has different effects on materials with different media properties, which is beneficial to the drying process characteristics, because water molecules have the best absorption effect on microwaves, so the part with the highest water content absorbs the most microwave power, only for microwave energy. The object is directly heated, and the air in the furnace body and the furnace chamber is hardly heated. When the microwave is heated, the heated material is generally placed in a heating container made of metal, and the heating chamber is a closed cavity for the electric wave, and the microwave It can not be leaked, it can only be absorbed by heated objects, and the air in the heating chamber and the corresponding container will not generate heat, so the thermal efficiency is extremely high, so it is efficient, energy-saving and improves the working environment.
3, no thermal inertia, that is, immediate. Therefore, high quality materials can be guaranteed.
4, easy to operate, suitable for control. Microwave heating can instantly achieve the purpose of lifting, opening and stopping, and the thermal inertia is very small. The application of PLC plus touch control panel is especially suitable for the specification and automation control of heating process and heating process.
5. Environmental protection, clean and hygienic. The equipment heating box is made of metal stainless steel, which can be cleaned with water. The discharging material is equipped with a fully sealed hopper and dust recovery device, and there is no “three wastesâ€.
6, safe and harmless. Microwave energy works in closed heating vessels and waveguides made of metal, and the energy leakage is extremely small. Our company's microwave equipment adopts advanced design and sophisticated processing to make microwaves into and out of the material inlet, observation window, furnace door, etc. Leakage is much better than national standards. This is a very safe heating and drying equipment because there is no radiation hazard and harmful gas emissions from microwaves.
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