Cyclone Design 
 Market Economy of 
 Xinhua Energy Equipment Co., Ltd. Tianjin 301900 

 Abstract The design of the structure of the cyclone analysis shows that the structure of the cyclone dust cyclone performance and life of, and improve the way the performance of cyclone; for the production and use of cyclone increased cyclone provide reference for the performance. 
 Key words dust cyclone system resistance calculation of cast iron lined 
 1 Overview 
 Nitrogen in small enterprises, making the section of gas behind the semi-water gas furnace to be arranged cyclone. Semi-water gas furnace as the technical requirements, go to the cyclone in the semi-water gas with a lot of dust (dust mixed in diameter, the maximum diameter of the dust particles up to 2mm, the smallest dust particle diameter ≤ 5цm); and Cyclones Precipitator effect of the back section in a direct impact on the life of the waste heat boiler. With the increasingly strict environmental requirements and continuous production of nitrogen fertilizer business more and more time, the role of cyclone also nitrogenous fertilizer attention. Cyclone dust removal and service life are the two major indicators of cyclone. 
 2. Cyclone collection efficiency of the design 
 2.1 cyclone theory and principle of the separation 

 Cyclone from the cylinder, cone, air intake, exhaust pipes, and dumping gray and other components, as shown in Figure 1. Cyclone dust-laden gas as the working process is the tangential inlet into the cyclone, the air will be a straight line motion into circular motion. Most of rotating flow lanes along the wall from the rotating cylinder-shaped downward flow toward the cone, said this is the external rotation flow. Dusty gas centrifugal force generated during rotation, the density of dust particles larger than the gas Shuaixiang the wall. Once the wall of dust exposure, they lost by radial inertia force and the downward momentum and gravity along the wall falling down into the ash tube. Decline in external rotation rotating cone gas reached, because of the contraction cone closer to the center. According to "spin torque" the same principle, increasing its tangential velocity, the centrifugal force dust suffered also been strengthened. When the air reaches the bottom of the cone, that is from the same direction of rotation of the central cyclone, up from the next reversal, continue to do spiral flow, the flow within the rotation. After the final purification of the gas discharge tube discharge tube device. 
 2.2 Cyclone collection efficiency 
 Grading is based on dust collection efficiency of different size represent the removal efficiency, its ability to reflect the dust particles of a size separation of capture capabilities. 
 Cyclone collection efficiency rating formula: 
 ηp = 1-e-0.6932dp/dc50 (1-1) 
 Where ηp - dp diameter of particles of dust collection efficiency,% 
 dp - dust particles diameter, цm 
 dc50 - 50% of cyclone critical particle size, цm 
 The total collection efficiency cyclone can be graded according to the dust collection efficiency and dust particle size distribution calculation. Of type (1-1) points, the total collection efficiency by cyclone calculation formula is as follows: 
 η = 0.6932dt / (0.6932dt + dc50) × 100% 
 dt = Σnidi4/Σnidi3 
 Η-cyclone dust collector where the total collection efficiency,% 
 dt - the quality of the average diameter of dust, цm 
 dt - the diameter of a dust grain size, цm 
 ni - di soot particle size of the percentage share of quality,% 
 Formulas from the above, the efficiency of dust Xuanfeng the main factors the following: 
 2.2.1 inlet velocity. Increased imports of gas flow cyclone, the centrifugal force by increasing dust, Cyclone dc50 critical size decreases, dust collection efficiency. 
 2.2.2 Cyclone size. The smaller the cyclone cylinder diameter, in the same tangential speed, the greater the centrifugal force dust suffered, the higher the collection efficiency. 
 2.2.3 The dust particle size and density. Suffered because of centrifugal force and the size of dust particles proportional to the cube, but suffered only a radial gas flow resistance is proportional with the size of a square, so large particles more than the capture of small particles. 
 2.2.4 Cyclone tightness. When leakage reached 15% capacity cyclone, collection efficiency is almost zero. 
 2.3 The Calculation of fluid resistance Cyclone 
 Cyclone fluid resistance can be imported mainly by the resistance, the vortex flow resistance and the resistance of the exhaust pipe of three parts to the following formula: 
 △ P = ξp2v2 / 2 
 △ P - Cyclone fluid resistance, Pa 
 ξ - Cyclone fluid resistance coefficient (usually achieved 6.5) 
 v - Cyclone fluid velocity, m / s 
 p2 - gas density, kg/m3 
 Analysis by the above formula, the efficiency of cyclone main factors are the following: 
 2.3.1 Structural Forms. If the structural form of the same cyclone, the cyclone the same as the resistance coefficient ξ. If the import of the same flow rate, pressure loss remain basically unchanged. 
 2.3.2 The air volume of imports. Pressure loss and flow rate proportional to the square of imports, which imports large amount of wind, pressure loss increases. 
 2.3.3 Size of Cyclone. Import area increases, the exhaust pipe diameter decreases, the pressure loss is even greater; with the cylinder and the cone part of the length increases. 
 2.3.4 Influence of gas density. Pressure loss increases with the gas density. 
 3, the structural design of cyclone (Figure 2) 
 3.1 Design of cyclone entrance 
 Cyclone gas flow rate of the general value of imports for the 15-22m / s. The total amount of the dusty gas flow rate calculated by dividing the import of cross-sectional area of ??cyclone inlet. Entrance height (H) is generally the width (B) twice. 
 The tangential inlet cyclone structure is usually rectangular cross-section flow channel. But the cyclone pipe in front of more than a circle, you need a circular to rectangular from over segment. (Figure 3) because changes in the flow channel may lead to fluid return the attached turbulent boundary layer separation and disturbance, so contraction angle does not exceed 21 degrees, spread angle does not exceed 15 degrees. 

 3.2 The length of cyclone design 
 Cyclone and straight diameter (D0) of the inlet height (H), 2.5 times the straight length of cyclone (L1) is a straight diameter (D0) 2 times. Cyclone Cone length (L2) is a straight diameter (D0) 2 times. 
 Many experiments show that increasing the length of the cyclone will be able to gradually improve the separation performance and reduced pressure drop; but the equipment of the production costs have increased. 
 3.3 Design of cyclone tube inside 
 The inner cyclone tube length (L) is a straight diameter (D0) of 0.5 times the diameter of the cylinder (DN) is a straight diameter (D0) of 0.5 times. 
 Cyclone concentric inner cylinder and outer cylinder, which extends the length of the inserted tube to the bottom flush with the entrance of the location. Tsinghua University study shows that the inner cylinder in the cyclone and the lower increase in the solid cores can reduce the pressure drop cyclone; open-loop operating conditions, the pressure loss decreased by 33%, closed-loop operating conditions, reduced by 20%. And collection efficiency will not change. 
 3.4 Cyclone Design discharge opening 
 Cyclone discharge port structure design, for the cyclone has been isolated from the coarse particles will be entrained into the vortex again, have a great impact. 
 The lower part of the cyclone, the vortex stabilizing device should be set (a simple "anti-inverted cone"), it can be installed in the discharge opening below or just above the discharge opening (Figure III). Steady vortex breaker is intended to provide a smooth end to the spiral surface, through the smooth surface, the vortex can be attached above it, and help set in the center rotating vortex. 
 4. Wear the anti-cyclone measures 
 Cyclone cyclone affecting the wear life of the main factors in the external conditions can not be changed, how to improve the wear resistance of cyclone cyclone dust collector is to improve the life of the main method. 
 Method using the anti-wear materials 4.1 
 Directly inside cyclone resistant cast iron, ceramic, granite and other materials wear better. Nitrogen is used by businesses are more wear-resistant cast iron; wear resistant cast iron is usually made into a round ring, thickness 20-50mm, height 200 mm, and the cast iron into mass production can be so easy parts replacement and equipment reduce equipment costs. 
 4.2 The painting method using the smear method is to wear-resistant material by a certain percentage after a good preparation, pre-filled into the inner surface of the cyclone is installed within the frame from the fixed effects, by turns solid, smooth, calendar, and a series of conservation anti-wear coating process to form methods. Here are a wear-resistant coating of water glass quartz sand mix; 60% quartz sand, bauxite clinker powder 30%, 8% sodium silicate, sodium fluoride 2%. 
 5 Conclusion 
 Small nitrogenous fertilizer enterprise in China's semi-water gas furnace constantly growing, production of steam continued to improve, the diameter of the cyclone is also growing that the device