With the continuous expansion of the production scale of the Laiwu Iron and Steel Group Co., Ltd. ironmaking plant (referred to as Laiwu Ironmaking Plant), the blast furnace smelting strength and utilization factor are increased, the air volume required for blast furnace production is also greatly increased, and with 4 × 120m3 blast furnace Among the 6 supporting fans, except for 1# and 5#, which are modified C430 fans, the other 4 units all use the C400-2.15 centrifugal blower matched with the 100m3 blast furnace. Due to the aging of the equipment, the efficiency of the fan is low, the air volume is low, and the wind pressure is low, which limits the iron production of the 4×120m3 blast furnace to a certain extent, which restricts the realization of the efficiency goal of the Laigang Ironmaking Plant. Therefore, it was decided to renovate the 3#C400 fan. The necessity of fan transformation The 3×C400 blast furnace 3#C400 fan body of Laiwu Iron and Steel Co., Ltd. is a single-suction and double-support structure, and the fan outlet air volume is 350-370Nm3. The requirement for the fan in the blast furnace production is firstly that there is sufficient air volume, and the air volume required for blast furnace smelting is 320.8 Nm3/t. The air volume of the supporting fan outlet should be 385Nm3/min. It can be seen that the airflow of the 3#C400 fan outlet is less than 385Nm3/min, which cannot meet the air volume required for the production of the 120m3 blast furnace. Therefore, it is necessary to carry out the transformation. Modification content Replacing the fan rotor and increasing the main air volume rotor is the core component of the fan. The centrifugal blower uses the centrifugal force generated by the rotation of the rotor impeller to squeeze the air to obtain energy to achieve a certain air volume and wind pressure. Under certain conditions, the air volume is directly related to the rotor diameter. To increase the air volume, it is necessary to increase the diameter of the rotor impeller, that is, to replace the fan rotor of the large diameter impeller. Transform the original C400 fan rotor into a C430 fan. The diameter of the modified fan impeller increased from 1170mm to 1230mm, and the fan outlet flow increased by 30m3/min. Redesigning the thrust bearing bushing airflow during the entire flow process, on the one hand, there is friction loss along the path, on the other hand, due to the separation of the boundary layer, eddy current loss occurs. If the impeller exit position deviates from the flow path, the gas resistance at the impeller exit increases, the flow rate decreases, the eddy current loss increases, and the turbine temperature increases, which increases the rotor size of the original C400 fan, which seriously affects the aerodynamic performance of the fan. In general, the impeller exit position should be in the center of the flow path to minimize eddy current losses due to boundary layer separation. Because this loss is one of the main reasons for the decline in export pressure. Since the diameter of the rotor impeller is increased, and the inclination angles of the front and rear discs of the impeller are not changed, the position of the impeller exit changes, and the impeller outlet is offset from the center of the fan air chamber. This will reduce the wind pressure and air volume of the fan, so the impeller outlet must be in the center of the flow path. However, in actual installation, the position of the center line of the impeller and the passage is not easy to find, and only by adjusting the gap between the front and rear discs of the impeller and the partition. After installing the new rotor, the gap between the front and rear discs of the rotor impeller and the fan diaphragm is measured as B1 is 21.9mm, the total gap difference between the two sides is 9.7mm. The axial adjustment of the rotor is 1.21mm. Therefore, it is decided to redesign, The compensation ring on both sides of the thrust bearing is manufactured, and the axial dimension of the left compensation ring is increased from 4.97mm to 6.17mm, and the axial dimension of the right compensation ring is reduced from the original 4.97mm to 3.77mm, and the position of the thrust bearing is adjusted to make the rotor shaft Move to adjust the gap between the front and rear discs of the impeller and the diaphragm. With the newly designed bearing compensation ring, on the one hand, the sealing of the gas seal can be adjusted, and on the other hand, the gap between the front and rear discs of the impeller and the partition plate can be adjusted, thereby ensuring that the position of the impeller outlet is substantially coincident with the center of the flow passage. . Reconstruction of the flexible coupling The new design of the rotor shaft end shaft with the key is 22mm × 160mm, and the original key is 24mm × 160mm, so the original coupling and the new shaft can not be matched. At the same time, it was found that the gap between the two elastic couplings of the original design was too small, and it was easy to generate large vibration and noise. The reasonable clearance between the flexible couplings is 4~7mm. The original coupling is turned to 4mm, and the 22mm×160mm keyway is inserted at the same time, which ensures the clearance between the two couplings and can be connected with the new rotor shaft. At the same time, reduce vibration and reduce noise. 3 transformation effect In the installation process, the joint centering method is adopted, the rotor installation is in place once, the test is successful once, and the construction period is shortened by 10 days. After the transformation, the 3#C430 fan runs smoothly, the air volume is increased from 350~370m3/min to 385~405m3/min, the air volume is increased by more than 10%, and the outlet wind pressure is increased from 0.10~0.11MPa before the transformation to 0.11~0.12MPa. The average bearing temperature is between 30 and 50 ° C, both less than 60 ° C, and the technical indicators are excellent. For the blast furnace, the effect is very obvious. From May to August 2001, the output of 2# blast furnace exceeded 10,000 tons continuously, and the average output of iron output increased by 30 tons, and the internal profit was 740,000 yuan. Combined Flow Closed Cooling Tower
Closed Cooling Tower is operated by circulating water or fluid, which is divided into two closed loops.
1. Circulation in the tower: the circulating water or fluid passes through the hot zone environment. After the water temperature rises, it enters the surface cooler in the tower, and the heat is sent to the environment outside the tower through the surface cooler and ventilation fan. The cooled circulating water or fluid is sent to the heat source by the water pump.
2. Circulation outside the tower: the spray water is sent to the spray system by the water tank through the water pipe. After spraying, the spray water first exchanges heat with the filler, so that the spray water can be cooled rapidly. At this time, the water contacts the surface of the surface cooler for heat exchange. Part of the hot steam is discharged through the ventilation fan, and the cooled spray water drops to the water tank for secondary circulation to form an external circulation for cooling.
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October 09, 2024