Generally, coal-based powdered activated carbon is produced in the form of other types of activated carbon by-products. In the case of separate production, the bulk raw coal is first crushed and sieved into raw coal powder of acceptable size according to the production process requirements, and then carbonized and activated. The finished powdered activated carbon, the process flow.
Coal-based powdered activated carbon is mainly used for upper and lower water treatment, 'waste incineration flue gas purification treatment and soil improvement. Because of the low market price, it is often not economically feasible to produce coal-based powdered activated carbon separately. There is basically no manufacturer of coal-based powdered activated carbon alone. At present, coal-based powdered activated carbon products are basically derived from the undersize produced by coal-based granular activated carbon producers at the same time as the production of granular activated carbon, and these undersize materials are ground into powdered powdered activated carbon for sale as a by-product. At present, foreign coal-based powdered activated carbon production enterprises only have Norit Company, which uses peat to produce coal-based powdered activated carbon for purification of waste incineration flue gas.
[The meaning of volatile matter and fixed carbon of coal-based activated carbon]
Coal-based activated carbon volatiles refer to the percentage of organic matter that is volatilized by coal at 900 ° C for 7 min under the condition of isolated air.
The volatile matter of coal is an indicator to measure the degree of coal metamorphism; as the degree of coal metamorphism increases, the volatile matter of coal decreases. Peat and lignite have the highest volatile matter, and anthracite has the lowest volatile matter. Generally, according to the requirements of activated carbon adsorption performance, coal with high or low volatile content is used for the production of activated carbon.
Bituminous coal, fat coal and other bituminous coal with medium volatile content are generally not used alone in the production of activated carbon. They are only used as coal blending to produce activated carbon to reduce the amount of tar, increase the strength of activated carbon and reduce the production cost; and peat and lignite with lower volatile content. Anthracite with higher volatile content can be directly used in the production of coal-based activated carbon.
In recent years, it has been found that a special processing technology is used to produce activated carbon products with special adsorption properties using coking coal as the main raw material coal.
The fixed carbon of coal is a solid residue of high-temperature pyrolysis of coal under isolated air conditions. In industrial analysis, fixed carbon does not need to be directly measured, and can be obtained by differential subtraction. As the degree of metamorphism increases, the fixed carbon content of coal increases, and the production of activated carbon with high metamorphism and high carbon content increases the yield.
[The grindability of coal-based activated carbon]
The grindability of coal reflects the difficulty of coal pulverization. This property should be considered when selecting a coal mill. The Hartgrove method is generally used to determine the grindability coefficient (HGZ) of coal. Its main principle is that the finer the coal is pulverized, the more the specific surface is increased, and the more the crushing work is consumed.
[Coal activated carbon reactivity]
Reactivity, also known as coal activity, refers to the ability of coal to react with different gasification media, such as CO 2 , 02 and water vapour, under certain temperature conditions. The highly reactive coal has a fast reaction rate and high efficiency during activation and combustion.
There are many methods for determining the reactivity of coal. At present, the method adopted in China is to determine the ability of coking to reduce CO2 in high-temperature carbonization of coal, and to indicate the reactivity of coal by the reduction rate of CO2.
The reactivity of various coals is weakened with the deepening of the degree of metamorphism. This is because the reaction of the carbon and L02 is carried out not only on the outer surface of the coal but also in the inner fine pores of the coal. The higher the porosity, the larger the specific surface. , the reactivity is strengthened. Generally, lignite is the most reactive, but when the temperature is higher (above 900 °C), the reactivity increases slowly; the anthracite has the weakest reactivity, but at higher temperatures, the reactivity increases significantly with increasing temperature.
When using coal to produce activated carbon, the process conditions should be determined according to the specificity of the coal reactivity, which can reduce the production cost of activated carbon.
The production of activated carbon requires high quality of raw coal. Generally, the ash content of coal is low and the reactivity is high. According to the requirements of adsorption performance and pore structure of activated carbon products, anthracite with low volatile content and high metamorphism is selected, or volatile matter is high. Forming bituminous coal with a similar age, such as non-stick coal, weakly cohesive coal and long-flame coal as raw coal for the production of activated carbon. Also consider the ash melting point, grindability, thermal stability and moisture when selecting activated carbon raw coal.
[In addition to activated carbon in the water purifier]
Activated carbon is a good thing, it can absorb and remove the color, smell, taste, colloid, residual chlorine, chloroform, carbon tetrachloride in water (the two are dangerous drugs that cause cancer, mutagenicity, and metamorphosis!) Organic things, etc., have a lot of effects and great credit.
The water purifier has evolved from simple filtration (rough filtration, such as PP cotton filter filtration, ceramic filtration) to the addition of activated carbon. It is a revolutionary leap. The use of activated carbon has become a major milestone in the history of water purifier development. Activated carbon has become a clean water. The most widely used and most commonly used water purification material.
But activated carbon is also a bad thing. It has one of the biggest drawbacks. It is the proliferation of bacteria. Because the tiny pores of activated carbon happen to be the breeding ground for bacteria, and the organic matter it absorbs is the rich nutrition of bacteria. Bacteria can multiply faster! It grows in geometric progression. The nitrifying bacteria in the bacteria will also make the ammonia nitrogen in the water form nitrite, and the combination of nitrite and ammonium in water will further produce nitrosamine, which can be a dangerous carcinogen for cancer! The deadly defect of activated carbon is brought to the user. It has caused great troubles, and it has made the road of purifying water purifiers difficult.
Nowadays, many people use membrane filtration water purifiers with reverse osmosis, nanofiltration, ultrafiltration and microfiltration. In theory, the pores of their membranes are less than 0.2μm, which is enough to block the passage of bacteria. But actually? If you have installed this kind of water purifier in your home for a month, you can check the water, you will find that the bacteria are beyond the standard. Why? Hollow fiber ultrafiltration membrane microfiltration membrane often breaks under the action of water pressure (even if a few thousand filaments just break a few, the bacteria in the water will sway from it); various membrane components and outer casing There is a gap in the water (the bacteria in the water will slip away from it); although the water purifier is sealed, the tap is always exposed to the air outside, and there is a lot of dust and bacteria attached to the dust in the air. The bacteria will enter the faucet, and the bacteria coming in from the faucet will move and penetrate into the water purifier, gradually spreading throughout the water purifier; the inner wall of the pressure tank and the rear activated carbon filter will multiply the bacteria.
Led Camp Light,Solar Led Camping Lights,Outdoor Solar Led Camp Bulb,Solar Camp Light
Shenzhen You&My Electronic Technology Co., Ltd , https://www.szyoumy.com