WIRE MESH DEMISTER was devised in the United States in the first half of 1940, and has been adopted in various plants, including petrochemicals, due to the dramatic development of the chemical industry in Japan. Mist separation contained in gas after air liquid contact is still widely used due to its advantages such as low pressure loss, high collection efficiency, and ease of installation. Our company has been well-received by delivering to all users under the motto of high performance and low price through our continuous research and improvement over many years. We look forward to your continued patronage. Function of Table of Contents Demi Star…………………2 Structure and Characteristics…………………………3 Materials and Applications…………………………4 Examples of equipment…………………………5 Styles and Features………………7 Grid and installation method…………8 Acceptable flow speed of design materials…………………………9 Pressure loss…………………………10 Collection efficiency…………………………11 Materials required for calculation………………13 air filter…………………14 Product Examples………………………………15 Related Products……………………………17 Materials and Corrosion Resistance Table…………………18
2 Demi Star is a collision-type separation device that aims to collect and remove impurities contained in gases, such as droplets, micromists, and dust of solid fine particles due to droplets, etc. by special metal wires. The collection function by Demi Star generally depends on the following action. １．Inertial collision 2. Diffusion by Brown motion of particles 3. Only 4. Gravitational deposition 5. Static deposition or adsorption 6. Heat deposition or adsorption The mist is collected and removed with high efficiency by these combined effects. However, 4. 5． 6． The action is usually negligible except in very small and special cases. Therefore, the collection function is mainly 1. 2． 3． It is considered to be an effect. If both mist diameter and airflow velocity are large, diffusion is dominant if both inertial collisions are small, and blocking is effective in the intermediate region between the two. If you explain the collection effect in the figure, it will be as follows. Fluid 1. Gas generated from the gas 2. 3. Rising the tower while containing liquid particles. Demi Star 5. It will collide with the line. The liquid particles contained at that time collide with the surface of the line article and fall as a large droplet 4. due to the "wet" of the line article and the surface tension of the liquid and the capillary phenomenon. Gas 6, separated from liquid particles, passes and rises without the interference of the Demi Star. １．Fluid 2. Rising gas 3. Airflow containing liquid particles 4. Drop droplets 5. Demi Star 6. Pure gas emitter action
3 Structural Demi Star is a complex structure formed by two nets woven with thin lines as shown in the photo, alternately waved, layered over multiple layers, and formed. The space ratio of Demi Star is extremely large at 94 to 99%, so the weight is light, and the entire surface of the wire material is in contact with space, so the surface area is very large and the pressure loss is small. Feature 1. Because it is lightweight, it is economical at a low price. ２．No need to pay for the maintainance cost. ３．Pressure loss is very low because the surface area is very large. ４． It is also easy to use for small device. ５．It is less constrained by dimensions and shapes during design. ６．It is easy to install on existing equipment. ７．Excellent in heat resistance and corrosion resistance. ８．High collection efficiency close to 100%. ９．High uniform fillability, and the pressure loss due to uneven filling is extremely small. Structure and Characteristics SK-192 SW-216 SW-432
4 Material and Application Material Demi Star has a wide range of application, and stainless steel can be produced mainly with the following materials. Stainless wire (SUS304, 304L, 316 316L) Inconel, Monel, Nickel, Titanium, Aluminum, Copper, True, Polypropylene, Fiberglass Demi Star is used in the following devices. Our main fields of use include organic chemistry, inorganic chemistry, coal chemistry, petroleum refining, and other industries. Absorbers …………………Absorption System Crystallizers ………………Crystal Device Cooling Towers ………………Cooling Tower Dehydraters ………………Dehydration device Deodorizers ………………Deodorizing Equipment Distillation Columns …………Distillation Tower Evaporators …………………Evaporator Fractionating Columns ………Gas Absorbers ………Gas absorber Gas Cleaners ……………Gas Clean Towers ……………Diffusion absorber Vacuum Pipe Stills …Vacuum type distillation system Wet Scrubbers ……Wet Gas Cleaner Dust Collectors ……………Dust collector
5 Example of equipment Gas Cleaning Tower Smoke Desulfurization Plant
6 Multi-stage flash type water plant Coating Pollution prevention equipment Waste Concentration Tower
Table 1. SK-80 It can be used at the highest airflow rate of all styles. １．Especially when the low pressure loss is required. ２．Conditions where clogging is likely to occur ３．Collection of large mist. ４．When high efficiency is not required. This style is usually used at a thickness of 150 mm, but it is necessary to increase the thickness further in order to achieve efficiency equivalent to SK-192. SK-192 is the most commonly used style. It is possible to obtain almost 100% collection efficiency for particles of 5 to 10μm. The pressure loss is slightly higher than the previous type. Used to collect SW-216 micro mist. Especially in the case of a low concentration of 10 g/m3 or less, it is effective to use it with a thickness of 200 to 300 mm. SW-432 is the highest density style. It is used to collect very fine mist at high efficiency, which is higher than SW-216. High efficiency is possible even if the thickness is thin. A Demi Star made from CMG fiberglass or synthetic fibers and made by a special knit manufacturing method. It is heat-resistant, acid-resistant, lightweight, and economical style, and has the same catch effect as other Demi stars. Style and its features SK-192 SW-216 SW-432 CMG
8 When installing a Demi Star in the instrument, it is necessary to ensure that it does not affect the performance of the catcher and droplets, etc., and maintain sufficient strength. If the tower diameter is small, a wire mesh or rod is used as a grid. The grid, like Demi Star, can be made with a wide range of materials. Although it depends on the conditions of use, double-sided grids are often used. Grid & Installation Method
9 Table 2. When installing a Demi Star in a device in the permissible flow velocity gas phase, the maximum allowable airflow velocity is obtained by the following equation to determine the optimal standard velocity of airflow passing through the catcher. U max : Acceptable airflow rate m/s ρl ：Mist density kg/m3 ρg ：Fluid density kg/m3 k1 ：Constant (Table 2) Here, ρl and ρg are used under the conditions at the time of use (temperature, pressure, etc.). The practical airflow rate is the range obtained by multiplying the upper formula by 0.2 to 1.0, and the optimal standard speed is Umax × 0.7. On the other hand, when installing in an existing tower, the flow rate of the treated fluid can be calculated based on the airflow rate obtained by the above formula and the size of the tank can be determined. Umax = k1 ρl-ρg expression (1.1) Graph 1.
10 Graph 2. Pressure loss The strength that Demi Star receives in the airflow as a uniform filling layer, that is, pressure loss, is obtained by the following equation. The force coefficient CD has a function relationship with the Reynolds number NRe when the fluid viscosity is μg, and in general, the approximate value is obtained by the following equations. CD＝８.４NRe -0.32…………………Equation (2.3) However, μg: Fluid viscosity Pa・s This is because the force D received by an object in the airflow is required by the following equation. ⊿P ：Pressure Loss Pa CD ：Strength factor ρg ：Fluid density kg/m3 U ：Airflow speed m/s L ：Filling layer thickness m Df ：Line diameter ml ：Line length A per unit volume in the uniform filling layer ：Area ε in the direction of the airflow of Demi Star ：Spatial rate P CDGgU2L (1− 2 π Df ε−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
11 Next, for each style (fill thickness and mist diameter), the relationship between air flow velocity and collection efficiency is similar to graph 4, and each style reaches maximum efficiency at 1 to 2 m/s, and the efficiency tends to decrease due to re-accompanying at the allowable flow velocity. When actually using Demi Star, there are many mist types and the average diameter of mist is unknown, and there is a slight error in the above efficiency calculation, but if you take an example of water droplets and air systems, it looks like graph 5. As you can see from graph 5, it is difficult to collect and remove with high efficiency at mist diameters of 1 to 2 μm or less, and it is necessary to increase the number of layers in order to achieve satisfactory effects. Collection efficiency Demi Star's theoretical formula for collection efficiency has been published by C, L, Carpenter, etc. E＝ １－ （1 －Et/C）N …………Equation (3.1) C = N/k2F ……………………Equation (3.2) E ：Demi Star's theoretical capture efficiency Et ：Mist collision efficiency C for one line of Demi Star ：Modification characteristics of Demi Star (Table 3) N ：Number of filling layers k2 ：Non-dimensional ratio F ：It is known that Et is affected by the line diameter, mist diameter, operating conditions, etc., and that there is a relationship between the Stalk number K and Et defined by the following formula. ……………Equation (3.3) K ：Stokes number ρl ：Mist density kg/m3 U ：Airflow speed m/s dl ：Mist diameter m μg ：Fluid viscosity Pa・s Df ：The theoretical efficiency E obtained from the line diameter m equation (3.1 to 3.3) matches well with the experimental values, and the collection efficiency can be estimated from the parameters and variables associated with the actual usage conditions of Demi Star. From graph 3, Et can be approximated by the following equation as a function of K. ……Equation (3.4) However, as can be seen from the above relations, the airflow velocity, mist diameter, and mist properties are closely related to the collection efficiency. （dℓ）2ρℓU K＝1 9 μgDf 1 －10 Et＝ －0.22(log 10K）2
12 Graph 3. Graph 4. Table 3. Graph 5.
13 Items required for calculation 1. Purpose of use and process 2. Gas name Pressure Pa temperature°C flow m3/h density kg/m3 viscosity Pa・s Other 3. mist name density kg/m3 concentration kg/m3 diameter μm Other 4. Demi Star tolerance pressure loss Pa Material desired efficiency % Other inquiries and orders, we will design the best style based on these materials. Please let us know as much as possible.
14 Air filter structure The Demi Star is coated with double-sided crimp wire mesh or metallasses and embedded in the frame. Feature 1. Low resistance and high collection efficiency. ２．It is especially suitable for places where dust is generated. ３．It has excellent heat resistance. ４．It can be used semi-permanently and economical. ５．Lightweight and easy handling. ６．It can be cleaned easily. Dimensions (example) 500×500×50t 500×1000×150t Production is possible even if it is not the above dimensions.
15 4. 3. 1. 2. 5. Product Example 1. Strip type 4 with double-sided grid. ２．Strip type 2-divided and non-divided double-sided grid. ３．Strip type fan shape 12 splits with double-sided grid. ４．Strip type 26-divided with double-sided grid. ５．Wound type with double-sided grid.
16 ６． ７． ９． 10． ８． 6. Strip type with 8 division reinforcement frame. ７．No sound type grit. ８．Mist catcher with cylindrical reinforcement frame. ９．Strip type with 4-divided double-sided grid. 10． Strip type 110 split with double-sided grid.
17 General-purpose stainless steel mount for filters for knit mesh cushions (for vibration, shock and noise prevention) Seal for silencer gaskets for radio waves and magnetic field failure shielding related products for wire mesh demister include a compressed processed product made from knit mesh as a material. Taking advantage of the excellent corrosion resistance and abrasion resistance of knit mesh, it is used in various fields, including pollution prevention, and its excellence has been proven. Our technical staff is looking forward to hearing from you.
18 Materials and Corrosion Resistance Table Tables Corrosion Resistance Tables
CATALOG NO.1802-7 06 (6562) 06 (6562) 2103 (3863) 010 FAX 03 (3863) 01 FAX 03 (3863) 03 (3863) 03 (3863) 03 (3863) 03 (3863) 03 (323) 110 FAX 052 (323) 12 (323) 123) 12 (123) 123) 12 (123) 12 (12 (12) 12 (12) 123) 12 (12) 123) 12 (12
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