1 Greetings WIRE MESH DEMISTER was invented in the United States in the first half of 1940, and has been adopted in various plants, including petrochemicals, as well as in Japan due to the rapid development of the chemical industry. Mist separation contained in gas after air-liquid contact is still widely used today due to advantages such as low pressure loss, high collection efficiency, and ease of installation. Our company has been well received by delivering products to all users under the motto of high performance and low price through many years of delivery experience and constant research and improvement. Thank you very much for your continued patronage. Contents of Demi Star's action…………………2 Structures and Features…………………………3 Materials and Applications…………………………4 Examples of equipment…………………………5 Styles and Its Features………………7 Grid and Mounting Method…………8 Design materials Acceptable flow velocity…………………………9 Pressure Loss…………………………10 Collection efficiency…………………………11 Materials required for calculation………………13 Air Filter…………………14 Examples of Products………………………………15 Related Products……………………………17 Table of materials and corrosion resistance…………………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 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 due to the brown motion of particles 3. blocking 4. gravity precipitation 5. static electricity deposition or adsorption 6. Heat deposition or adsorption The mist is collected and removed with high efficiency by these comprehensive action. However, 4. 5． 6． The action is usually ignorable except in very small and special cases. Therefore, the collection function is mainly 1. 2． 3． It is considered to be a syntax. If the mist diameter and airflow velocity are both large, inertial collisions are likely to be dominant, and if both are small, diffusion is dominant, and blocking will be effective in the intermediate region of both. If you explain the collection effect in the figure, it will be as follows. Fluid 1. Gas generated in the gas 2. In addition to liquid particles, climb up 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, and gradually fall as large droplets 4. due to the "wet" of the line and the surface tension of the liquid and the capillary phenomenon. Gas separated from liquid particles 6. passes through without the interference of Demi Stars. １．Fluid 2. rising gas 3. Air current containing liquid particles 4. Drop droplets falling 5. Demi Star 6. Pure Gas Demister action
3 Structural Demi Star is a complex structure formed by two nets woven with thin lines as shown in the photo, alternate wave is applied, layered over layers, and molded. Since the space ratio of Demi Star is extremely large at 94-99%, the weight is light, and the entire surface of the wire material is in contact with the space, the surface area is very large and the pressure loss is small. Feature 1. Because it is lightweight, it is low price and economical. 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 fillability and the pressure loss due to uneven filling is extremely small. Structure and Features SK-192 SW-216 SW-432
4 Material and Application Material Demi Star has a wide range of application, and can be made mainly of stainless steel with the following materials. Stainless wire (SUS304, 304L, 316 316L) Inconel, Monel, Nickel, Titanium, aluminum, copper, true, polypropylene and glass fiber Demi Star is used in the equipment as shown below. Major fields of use include organic chemistry, inorganic chemistry, coal chemistry, petroleum refining, and other industries. Absorbers …………………Absorber Crystallizers ………………Crystalline Equipment Cooling Towers ………………Cooling Tower Dehydraters ………………Deodorizers dewatering equipment ………………Deodorization equipment Distillation Columns …………Distilled Tower Evaporators …………………Evaporator Fractionating Columns ………Gas Absorbers ………Gas Cleaners ……………Spray Towers Gas Clean Towers ……………Diffusion absorber Vacuum Pipe Stills …Vacuum-type distillation system Wet Scrubbers ……Wet gas cleanser Dust Collectors ……………Dust collector
5 Examples of equipment Gas Washing Tower Smoke Desulfurization Plant
6 Multi-stage flash water plant paint pollution prevention equipment Waste liquid concentration tower
7 Table 1.SK-80 This can be used at the highest air current 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 with a thickness of 150 mm, but further thickness needs to be increased in order to achieve an efficiency equivalent to SK-192. SK-192 This 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. SW-216 Used to collect micromists. Especially when the amount of mist is lower than 10 g/m3, it is effective to use it with a thickness of 200 to 300 mm. SW-432 is the most dense 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 glass fiber or synthetic fiber using a special knit method. It has a style rich in heat resistance, acid resistance, light weight, and economic efficiency, and has a collection effect as much as other Demi stars. Style and Its Features SK-192 SW-216 SW-432 CMG
8 When mounting a Demi star in the instrument, it is necessary to ensure that it does not affect the performance of the collector and droplet droplets, and maintain sufficient strength. If the tower diameter is small, a wire mesh or rod is used as a grid. The grid can be made with a wide range of materials, just like Demi Stars. Depending on the usage conditions, double-sided grids are often used. Grid and Mounting Method
9 Table 2. When a Demi Star is mounted on a device in the allowable flow velocity of design materials, the maximum allowable airflow speed is determined by the following equation to determine the optimal standard speed of the airflow passing through the collector. U max : Allowable airflow speed m/s ρl ：Mist density kg/m3 ρg ：Fluid density kg/m3 k1 ：Constant (Table 2) Here, ρl and ρg are values under the conditions at the time of use (temperature, pressure, etc.). The practical airflow speed is the range obtained by multiplying the above equation by 0.2 to 1.0, and the optimal standard speed is Umax x 0.7. Conversely, when mounting to an existing tower, the flow rate of the treated fluid can be calculated based on the airflow rate obtained by the above equation, and the size of the tank can be determined. Umax = k1 ρl-ρg ρg expression (1.1) Graph 1.
10 Graph 2. Pressure loss The anti force that a Demi star in the air current receives in the unit area as a uniform filling layer, that is, pressure loss is determined by the following equation. When the fluid viscosity is μg, the anti-force factor CD has a function relationship with the Reynolds number NRe, and in general, approximate values are obtained by the following equations. CD＝８.４NRe -0.32…………………Equation (2.3) However, μg: Fluid viscosity Pa s This is due to the following equation that the anti force D received by an object in the airflow direction per projected area in the airflow direction. ⊿P ：Pressure loss Pa CD ：Anti force coefficient ρg ：Fluid density kg/m3 U ：Airflow velocity m/s L ：Thickness of the filling layer m Df ：Line length ml ：Line length A per unit volume in the uniform filling layer ：Area ε in the airflow direction of Demi star ：Spatial rate P = ρgU2L (1-222222D D (2.1) type ((2.1 D = CD ρgU2 2LD = 2LD = 1- εDf 2) πDf − − − − − − − − − − − − − space ratio P = − − − − − − − − − − − − − − − − − − − − − − − space ratio P= − − − − − − − − − − − − − − − − space ratio P = − − − − − − − − −
11 Next, for each style (fill thickness and mist diameter), the relationship between airflow velocity and collection efficiency is as shown in graph 4, and the airflow velocity tends to reach the maximum efficiency at 1 to 2 m/s in each style, and the efficiency tends to decrease due to reaccompany over the allowable flow velocity. When actually using Demi Star, there are many types of mist or the average diameter of the mist is unknown, resulting in some errors in the efficiency calculation above, but as an example of the system of water drops and air, it is shown in 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 is required to obtain a satisfactory effect. Collection efficiency It has been announced by C, L, Carpenter, etc. as a theoretical formula for the collection efficiency of Demi stars. E＝ １－ （1 －Et/C）N …………Equation (3.1) C = N/k2F ……………………Equation (3.2) E ：Demi Star's theoretical collection efficiency Et ：Mist collision efficiency C against one line of Demi Stars ：Modification Characteristics of Demi Stars (Table 3) N ：Number of filling layers k2 ：Non-dimensional ratio F ：It is known that Et is affected by the line length, mist diameter, operating conditions, etc., and that there is a relationship as shown in graph 3 between K and Et, defined in the following formula. ……………Equation (3.3) K ：Number of Stokes ρl ：Mist density kg/m3 U ：Airflow speed m/s dl ：Mist diameter m μg ：Fluid viscosity Pa s Df ：Theoretical efficiency E obtained from the line length m expression (3.1 to 3.3) is well matched with the experimental values, and the collection efficiency can be estimated and calculated based on 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, 0.1 ≤ K ≤ 100 As can be seen from the above relationship, the 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 rate 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 % For inquiries and ordering, please let us know the most suitable style according to these materials.
14 Air Filter Structure The Demi Star is superimposed by double-sided crimp wire mesh or metallic 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 excels in heat resistance. ４．It can be used semi-permanently and economical. ５．Lightweight and easy to handle. ６．It is easy to clean. Dimensions (example) 500 x 500 x 50t 500 x 1000 x 150t Production can be made with anything other than the above dimensions.
15 4.3.1.2.5. Product example 1. Strip type with 4-divided double-sided grid. ２．With 2-divided strip type and non-divided double-sided grid. ３．With a strip-type fan-shaped 12-divided double-sided grid. ４．With 26-divided double-sided grid. ５．With bonded double-sided grid.
16 ６． ７． ９． 10． ８． 6. With a strip type 8-divided reinforcement frame. ７．There is no warped type grit. ８．With a mist catcher cylindrical reinforcing frame. ９．Features 4-divided double-sided grid. 10． With 110-divided double-sided grid.
17 General-purpose stainless-mount stainless steel mount for filters for knit mesh cushions (for vibration, shock, noise prevention) Seal for gaskets for silencers and related products for shielding magnetic field disorders As related products of wiremesh Demister, we have processed products made from knit mesh materials. Utilizing the excellent corrosion resistance and mamminch resistance of knit mesh, it has been used in various fields, including pollution prevention, and its excellence has been proven. Our technical staff is looking forward to your consultation.
18 Materials and corrosion resistance Table materials Table of corrosion resistance
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