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 today due to its advantages such as low pressure loss, high capture 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 Design materials allowable flow speed…………………………9 Pressure loss…………………………10 capture efficiency…………………………11 Materials required for calculation………………13 air filter…………………14 Product Examples………………………………15 Related Products……………………………17 Material 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, dust of solid particles, etc. by special metal wire clauses. The collection function by Demi Star generally depends on the following action. １．Inertial collision 2. Diffusion by Brown motion of particles 3. Secret 4. Gravitational deposition 5. Electrostatic deposition or adsorption 6. Heat deposition or adsorption These combined effects capture and remove mist with high efficiency. But 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 the mist diameter and airflow velocity are both large, the inertial collision is dominated, and if both are small, the diffusion is dominated, and the intermediate region between the two is considered to be effective. If you explain the collection effect in the figure, it will be as follows. Fluid 1. Gas generated from inside 2. Liquid particles are raised in the tower 3. Demi Star 5. It collides with the line. The liquid particles contained at that time collide with the surface of the line article, and the surface tension of the liquid and the capillary phenomenon gradually fall into large droplets 4. Gas separated from liquid particles 6. passes and rises without the interference of 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 knitted with thin lines as shown in the photo, alternately waved, layered on multiple layers, and molded. 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 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．It has high uniform filling properties, and the pressure loss due to the 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 wires (SUS304, 304L, 316 316L) Inconel, Monel, Nickel, Titanium, Aluminum, Copper, True, Polypropylene and Fiberglass Demi Stars are 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 ………………Dewatering device Deodorizers ………………Deodorizing Equipment Distillation Columns …………Distillery 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 Exhaust Smoke Desulfurization Plant
6 Multi-stage flash type water plant coating pollution prevention equipment waste liquid concentrating tower
Table 1. SK-80 This product can be used at the highest airflow speed 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 150mm, but it is necessary to increase the thickness in order to achieve an 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 micromist. In particular, if the concentration of mist is less than 10 g/m3, it is effective to use it at 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. Demi Star made of CMG fiberglass or synthetic fibers and made by special knit manufacturing method. It has a heat-resistant, acid-resistant, lightweight and economical style that 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 maintain sufficient strength without affecting the performance of the catcher and droplet droplets, etc. 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 usage conditions, double-sided grids are often used. Grid & Installation Method
9 Table 2. When installing a Demi Star in a device in the allowable flow velocity of the design materials, the maximum allowable airflow velocity is determined by the following equation to determine the optimal standard velocity of the airflow passing through the catcher. U max : Acceptable airflow speed m/s ρl ：Mist density kg/m3 ρg ：Fluid density kg/m3 k1 ：Constant (Table 2) Here, ρl and ρg use values 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 = 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 force that Demi Star receives in the unit area as a uniform filling layer, i.e. pressure loss, is calculated 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 the object in the airflow is calculated by the following equation. ⊿P ：Pressure Loss Pa CD ：Strength coefficient ρg ：Fluid density kg/m3 U ：Air flow velocity m/s L ：The thickness of the filling layer m Df ：Line column diameter ml ：Line length A per unit volume in uniform filling layer ：Area ε in the direction of the airflow of Demi Star ：Spatial rate P = 1- 2π Df equation (2.1) D = 2.2 ρgU2 2 1A = 1-πDf 2) Df −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
11 Next, for each style (fill thickness and mist diameter), the relationship between air flow velocity and collection efficiency is as shown in graph 4, and each style reaches maximum efficiency at 1 to 2 m/s, and the efficiency tends to decrease due to reaccompanying above the allowable flow velocity. When actually using Demi Star, there are many mist types and the average diameter of the mist is unknown, and there is a slight error in the efficiency calculation above, but if you take an example of water droplets and air systems, it looks like graph 5. As can be seen from graph 5, it is difficult to collect and remove with high efficiency at a mist diameter of 1 to 2 μm or less, and a considerable number of layers must be increased 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 against 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 in the following equation as shown in graph 3. ……………Equation (3.3) K ：Stokes number ρl ：Mist density kg/m3 U ：Air flow velocity m/s dl ：Mist diameter m μg ：Fluid viscosity Pa・s Df ：The theoretical efficiency E obtained from the line diameter m equations (3.1 to 3.3) is well matched with the experimental values, and from these equations, the collection efficiency can be estimated from the parameters and variables associated with the actual conditions of use of Demi Star. From graph 3, Et can be approximated by the following expression as a function of K. ……Equation (3.4) However, 0.1 ≤ K≤ 100 As can be seen from the above relationship, airflow velocity, mist diameter, and mist properties have a close relationship with 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 When making inquiries or ordering, we will design the most suitable style based on these materials, so please let us know as much as possible.
14 Air filter structure The Demi Star is layered overlaid with double-sided crimp wire mesh or metalllas, and incorporated into 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 is easy to clean. Dimension (Example) 500 x 500 x 50 tons 500 x 1000 x 150 tons Production is possible with items other than the above dimensions.
15 4. 3. 1. 2. 5. Product Example 1. Strip type 4 with double-sided grid. ２．Strip type 2 division and non-divided double-sided grid. ３．Strip type fan shape with 12-divided double-sided grid. ４．Strip type with 26-divided double-sided grid. ５．Wound type with double-sided grid.
16 ６． ７． ９． 10． ８． 6. Strip type with reinforcement frame for 8 division. ７．No sound type grit. ８．Mist catcher with cylindrical reinforcement frame. ９．Strip type with 4-divided double-sided grid. 10． Strip type with 110 split double-sided grid.
17 General-purpose stainless mount for filter for knit mesh cushions (for vibration, shock and noise prevention) Seal for silencer gaskets related to radio waves and magnetic field failure shielding related products related to wire mesh demosters are made from knit mesh. Taking advantage of the excellent corrosion resistance and wear 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 Material and corrosion resistance table material table corrosion resistance table
1802-7 06 (6562) 2103 (3863) 0103 (3863) 0103 (3863) 1281 (3863) 010 FAX 122 (323) 122 (323) 1220 20 20 20 2481) 7082 (481) 7082 072 (759) 1015 FAX 012 (323) 12 012 (380707070707072-2-2-2-2-72-2-2-72-7070708072-72-7
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