What is the filter material used for blast furnace gas purification in iron and steel plants?

Application field: blast furnace gas purification bag filter in iron and steel plant.

SINO recommendation: FMS composite high-temperature resistant filter material.

Product performance analysis and comparison:

A. Overview

Blast furnace gas is an important secondary energy source in metallurgical systems, accounting for 10-20% of the total energy consumption of iron and steel complexes. At present, blast furnace gas has become the main fuel gas for hot blast stoves, coke ovens, steel rolling furnaces (mixed with high calorific value dyes), and medium and low-pressure blast furnaces.

Due to the low calorific value of blast furnace gas, it is highly toxic and has a wide explosion range, and its availability is small. At the same time, the by-product blast furnace gas of iron and steel complexes generally has a large amount. There is a common problem of gas emissions in various metallurgical enterprises. On the one hand, it causes energy waste; on the other hand, it causes environmental pollution. Therefore, how to use blast furnace gas reasonably and economically has become a major research topic for metallurgical systems.

At the same time, due to the large dust content in blast furnace gas, it is not easy to directly enter the gas pipe network for use. It must be purified and dedusted through the process to reduce the dust content of blast furnace gas. Generally, it is required that the dust content of the gas is less than 10mg/Nm3. Ensure the normal use of associated equipment. At present, the wet purification process is generally used in the treatment of blast furnace gas, mainly through gas scrubbers and venturi tube wet dust collectors. However, compared with dry blast furnace gas purification pulse bag dust collectors, the system process is still complicated. , large investment costs, large water consumption and energy loss, and serious secondary pollution, etc., so the pulse bag dust removal equipment for dry purification of blast furnace gas has been developed rapidly in foreign countries.

With the continuous development of bag dust removal technology and filter materials, the use of bag dust removal equipment in blast furnace gas dry purification has been widely used and promoted in countries all over the world because it overcomes the shortcomings of dry electrostatic precipitators and saves investment. , especially in small and medium-sized blast furnaces (≤1000m3), at present, there are more than 500 pulse bag filters used in the dry purification of blast furnace gas in the world, among which the maximum treatment flue gas volume reaches 1 million m3/h.

B. Performance advantages of FMS needle felt

1. Overview

my country's ironmaking blast furnace gas bag filter process started in 1974. With the development of dust collector technology, the filter materials have developed from glass fiber cloth, glass fiber needle felt, and METAMAX needle felt most of which use FMS composite resistance For high-temperature filter material products, the market demand for needle-punched filter felt has increased significantly year after year, which has also promoted the rapid development of the emerging industry of needle-punched filter felt. From the perspective of product market structure, high-temperature-resistant organic fibers have the advantages of long service life and high filtration precision, but the use temperature is limited, the size is unstable, the product price is too high, and users are difficult to accept and other problems seriously restrict the development of this product. However, high-temperature-resistant inorganic fibers have problems such as non-abrasion resistance, non-folding resistance, short service life, and low filtration accuracy, which cannot meet the requirements of the growing environmental protection industry.

FMS needle-punched filter felt products were developed from 1997 to 1998 and applied for national patents. In 2003, they passed the appraisal of scientific and technological achievements. FMS needle-punched filter felt has the characteristics of high-temperature resistance, corrosion resistance, large air volume, and long service life. It is made by blending several kinds of high-temperature resistant fibers with glass fibers in different proportions and needle-punching into mats, and then finishing with fluorine-containing additives. The product has good wear resistance and folding resistance, and the outlet emission concentration is extremely low. It is mainly used in the treatment of high-temperature flue gas such as blast furnace gas purification in ironworks. After mass production and promotion in recent years, good results have been achieved.

FMS needle-punched filter felt is a deep filter medium made of three-dimensional fibers interconnected. It is a permeable material with a large number of semi-through holes and through holes inside. Its filtering action occurs throughout its thickness. Part of the dirt particles are blocked on the surface close to the upstream, and some smaller particles enter the interior of the filter medium. Under the effects of shrinkage, expansion, and pressure effects, they are adsorbed on the pore wall and deposited to form a dusty shelf. The gas is removed from the gap, and the particles are It is blocked inside the dust rack. Therefore, its structure determines that FMS® needle-punched filter felt has the advantages of low-pressure loss, high filtration accuracy, large dirt-holding capacity, high filtration efficiency, and long life.

2. Performance analysis of FMS high-temperature resistant filter material

Through scientific arrangement and combination, we have obtained a batch of new varieties of high-temperature filter materials with similar main body high-temperature resistance properties and completely different special properties. These varieties basically develop the strengths of the two fiber materials and make up for their respective shortcomings. . The following conclusions can be drawn from laboratory tests and field applications:

(1) It can significantly increase the strength of the filter material and reduce the elongation

The warp and weft tensile strength of FMS needle-punched filter felt is above 2000 Newtons, which is about twice as high as that of chemical fiber filter materials, and the elongation at break is between 3 and 10%. The material has good dimensional stability during use and is not easy to elongate and deform. This feature makes it significantly improves the cleaning effect, reduces resistance, and prolongs the service life in the blast furnace gas long bag reverse (suction) blowing dust collector.

(2) It can significantly improve temperature resistance

The high-temperature filter material made by mixing carbon fiber and glass fiber can withstand temperatures above 400°C FMS 9806 filter mat produced by mixing P84 fiber with glass fiber has significantly higher temperature resistance than P84 high-temperature felt made of pure P84 fiber. In the experiment, FMS 9806 was placed in an oven at 300°C for 24 hours. In the laboratory test, its shrinkage rate was less than 1%, and its strength was basically not reduced.

(3) It can significantly improve wear resistance

Tested by the flat grinding test machine, compared with the glass fiber needle felt, the wear resistance of the Flumes filter material is significantly improved. (The abrasion resistance of Flumes filter material is 2200-3000 times, and the abrasion resistance of glass fiber filter material is 538 times).

(4) It can significantly reduce running resistance

Because the glass fiber is mixed with chemical fibers that are easy to needle-punched and finished, it is more conducive to the smoothness and compactness of the filter mat, the surface is smooth and smooth, easy to clean dust, and the running resistance is low. If the P84 fiber layer is compounded on The surface of the filter felt has a better filtering effect.

(5) It can significantly increase the filtration wind speed and reduce the volume of the dust collector

Because FMS filter felt has high mechanical strength, good wear resistance, and folding resistance, it can be used normally at a filtration wind speed greater than 1m/min, so the wind speed can be selected to be higher, and the volume of the dust collector and the filter area can be smaller, saving energy.

(6) FMS high-temperature resistant filter material is cheap and more acceptable to users

Because FMS filter material is a mixed material of glass fiber and chemical fiber, the manufacturing cost is 50-60% of the imported high-temperature-resistant chemical filter material of the same type and performance, which can greatly save the cost of use. 

C. Comparison of FMS 9806 and glass fiber needle-punched filter felt in the application of blast furnace gas bag filter

Glass fiber needle felt is the needle-punched filter material first used in blast furnace gas dedusting. Due to the low coefficient of friction on the surface of glass fibers, ordinary post-treated needle felts are easy to cause the fibers to slip during use, showing very low peeling resistance and folding resistance. In addition, the slip will make the needle punched structure This is the most important reason why the glass fiber needle felt has good chemical resistance, and stable dimensions but low service life.

FMS 9806 needle-punched filter felt is processed to form a discontinuous film on the surface of the fibers and between the fibers, so that the fibers and the fibers and the base fabric cannot slip relative to each other within a certain force range, and The felt structure is improved, not only the anti-peeling performance and wear resistance and folding resistance are greatly improved, but also the filtration performance and filtration precision are improved due to the optimized internal porosity.