Shougang Jingtang Company has two oxygen-making air compressors, which provide raw air for the production of various gaseous media for two air separation systems. The air compressor is produced by MANTURBO. The model and parameters are as follows: Type: single shaft, centrifugal compressor, model: RIKT140-1 Operating medium: air, rated flow: 382900m3/h Operating temperature: population: 27.6 QC, outlet shaft power : 29500 kW, rated speed: 4398 r / min Intercooler total water consumption: 1750m3 / h gives a schematic diagram of the air compressor structure.
It can be seen that the air compressor has three stages of impellers, and two sets of coolers are vertically installed on the left and right sides of the first stage impeller and the second stage impeller outlet. The air enters the body by the population guide vanes, and is discharged through the first impeller, the primary cooler, the secondary impeller, the secondary cooler and the tertiary impeller. In the figure, the two bearings of the air compressor are drawn on the outside of the machine body in an express manner, and in fact, the bearing and the air compressor are integrated structures.
2 The fault was scheduled to be overhauled for 6 days on April 24, 2013. The main contents of the overhaul included the measurement and inspection of the parameters of the main engine, the replacement of the primary cooler, the cleaning of the secondary cooler, and the impeller. Non-destructive testing and so on. On April 30th, the test was carried out as scheduled. After the rated speed was reached, all the parameters of all parts were normal except the vibration amplitude of the bearing end of the air compressor. The vibration amplitude of the bearing end of the air compressor is always between 6065fxm, which is only one step away from the preset alarm value 68fxm. This parameter is only 25fxm before the inspection. Therefore, it is considered that the air compressor has vibration failure.
3Fault analysis and treatment 3.1 Preparation work The air compressor has been observed and operated, and the pressure, temperature, vibration and other instruments of the air compressor have been carefully and meticulously checked, and the display of each part is accurate and true, and the data during analysis is ensured. The truth is guilty.
3.2 Phenomenon Analysis When tracking and analyzing various parameters, the following phenomena were found: (1) During the maintenance of the primary cooling tower, the total water supply temperature of the cooling water increased slightly, 2 the vibration of the drive end of the air compressor, 1 air pressure The machine vibration value is stable.
(2) During operation, it was found that the vibration value of the drive of the two machines increased when the air separation load decreased.
(3) The cooling effect of the two sets of coolers on the left and right sides of the air compressor is different. In April, when the annual repair was completed, a new cooler was replaced on the right side of the first stage. The left side is still the old cooler. At present, the right side exhaust temperature is 10 times lower than the left side exhaust temperature.
3.3 Analysis and elimination of influencing factors Combined with the above-mentioned phenomena and previous maintenance experience, the influencing factors that may cause vibration failure of air compressors are analyzed and verified one by one. 3.3.1 Influence of various parameters of the main body of the main body After the vibration of the air compressor, we first think about the bearing bush clearance, the pressing force, the rotor runout value and whether the axial pairing parameters meet the requirements, and review it again by the maintenance data and maintenance standards at that time. After comparison, it is considered that the maintenance process is reasonable and the parameters are accurate, all within the standard range.
3.3.2 Water temperature influence The relationship between cooling water temperature and air compressor vibration is an indirect influence. First, when the temperature of the cooling water changes, the temperature and viscosity of the lubricating oil change, and the properties of the lubricating oil film change, and the vibration condition also changes. Secondly, the change of the temperature of the cooling water will cause the temperature of the air discharged from the cooler to change, and the change is transmitted to the impeller, which causes the force state of the rotor to change. The following three water temperature experiments were conducted to determine whether the water temperature had a substantial effect on the vibration of the air compressor.
(1) On May 14th, the water temperature test was carried out. The cooling water temperature increased by 3.1%, the lubricating oil supply temperature increased by 0.7%, and the air compressor vibration value increased from 63 滋m to 68.3 滋m alarm, 1 empty. There is no change in the vibration value of the press.
The side cooler outlet water temperature was adjusted, and the drive end bushing vibration did not change when the outlet water temperature was the same.
The cooling water outlet valve opening is adjusted to reduce the exhaust temperature difference from 10 to 7.1, and the vibration value is slightly reduced but not very obvious. Since the opening degree of the right side valve is already small at this time, the adjustment may cause the valve to be completely closed, so that the temperature difference between the left and right sides may not be further reduced.
It can be known from the above test process that the change in water temperature does have an effect on the vibration of the air compressor, but this is an indirect effect. A small change in water temperature can only cause a slight change in the temperature of the lubricating oil, and the properties of the oil film remain unchanged, so the vibration of the air compressor does not change. Therefore, there is only one possibility that the change in water temperature changes the exhaust temperature of the interstage cooler, and the final manifestation is that the vibration of the air compressor changes.
3.3.3 Impact of air separation load On May 15th, the effect of air separation load change on the vibration of bearing of 2 air compressors was tested. The results are as follows: there is a change; the load of 19:00 is adjusted from 88% to 100% to 21 There is no change in the vibration of :00; thus, the air separation load has no effect on the vibration of the air compressor.
3.3.4 Rotor dynamic balance factors Whether the rotor dynamic balance is good or not has a great influence on the vibration of the air compressor, and it also has an absolutely high proportion in the cause of various mechanical vibration failures. 2 The air compressor has good vibration before maintenance, and there is no dynamic balance problem; the scale on the rotor is cleaned during the maintenance process, the cleaning work is thorough, there is no dead angle, so the possibility of causing dynamic imbalance is very small. Basically can be excluded.
3.3.5 Unbalanced exhaust temperature between stages In order to eliminate the imbalance of the exhaust temperature of the primary air cooler of the 2 air compressor, a new cooler was replaced on the left side of the first stage on June 17. After the start-up, the exhaust temperature of the first two sets of coolers was 25.1 and 25.8, respectively, and the temperature difference was reduced to 1 benefit; the vibration value of the bearing bush was also greatly reduced to 29.19 m, and the vibration fault was finally solved.
3.4 Analysis of the causes Through the theoretical analysis and experimental verification of various factors, the results are clear and clear: the fundamental reason for the high vibration of the drive end of the 2 air compressors is that the heat exchange efficiency of the first two sets of coolers is different, and the temperature difference of the discharged gases is large. The mechanism of the effect of this temperature difference on the vibration of the air compressor can be explained in two aspects. First, for the air compressor in which the bearing and the body are in an integrated structure, a large temperature difference causes uneven thermal deformation on both sides of the bearing body and the casing, thereby causing a gap between the bearing bush and the dynamic and static gap between the rotor and the casing. change. On the other hand, the temperature is different and the air density is necessarily different. The high temperature side has a small gas density and a large flow rate; the low temperature side has a high gas density and a small flow rate. After rough estimation, the flow difference between the two sides reaches 7000m3/h. Such a large flow difference will inevitably form an additional couple on the impeller after entering the lower impeller, causing the rotor to be unbalanced.
4 Conclusions (1) The factors affecting the vibration of air compressors are complicated. Therefore, it is necessary to pay attention to comprehensive analysis, pay attention to the changes of various equipment parameters, correlate parameters, and find problems as early as possible to prevent the situation from deteriorating.
For the flow of the metallurgical power slag water of the cooler to the left and right (down to page 44), the flow rate of the commercial hot water is automatically adjusted, so the flow of the heated tap water is controlled by controlling the amount of slag water introduced into the heat exchanger, when the commercial hot water When the demand is large, the slag water is increased accordingly to increase the flow rate of the pump. When the demand for hot water is small, the amount of slag water used for heating is also reduced accordingly, and the excess slag water is still sent to the cooling tower for cooling.
2.3 Reconstruction The project is invested and constructed by the hot water company and is responsible for the hot water transportation and sales of commercial hot water. We provide tap water and electricity points according to the site layout, and charge the heat energy usage fee according to the quantity of hot water sold. In this transformation, three new slag water lifting pumps were added to send three sets of intelligent heat exchangers, and steam heaters were added to heat the commercial hot water to the temperature required by the user. The taxi is transported to the user's point, and the relevant meter is also used for the measurement of hot water and steam flow and temperature of the commodity.
Since the slag water has certain corrosiveness and is affected by the stage slag, the heat exchanger and the lifting water chestnut are all made of non-pound steel, and the heat exchanger is designed to operate at a low flow rate. The temperature of commercial hot water varies according to different user needs. Therefore, manual control is adopted. In summer, the tap water temperature is higher and the demand is less. The water temperature can reach 70%, which basically meets the user's demand, without steam heating. Consider the commodity heat. The market demand for water, the current configuration of slag water to enhance the capacity of the pump and heat exchanger is limited, in the case of low tap water temperature and large demand in winter, it is necessary to use part of the steam for reheating of hot water, when the user demand is stable, then The situation adds the ability to lift the chestnut and heat exchanger. The system retains the cooling tower system for cooling the remaining slag water.
(Continued from page 42) The air compressor of the installation type will cause serious vibration of the air compressor when the exhaust temperature of the left and right coolers is not balanced. This has not been mentioned yet and should be highly valued. In order to make the air compressor in good operating condition, it is recommended to control the temperature difference between the exhaust gas in the stage. The operation effect and benefit analysis of the project are completed. The slag water heating and hot water project was completed and put into operation at the beginning of this year. According to the operation situation in the past six months, the whole system runs smoothly, the heat exchanger reaches the designed heat exchange efficiency, and there is no fault phenomenon that affects the slag slag. According to the statistics of operation data, from January to May, the cumulative production of commercial hot water was 72884t, and the average temperature of water temperature rose by 50%. The accumulated heat recovery was: 72884x50x4.18=15233GJ, equivalent to standard coal: 520t. The thermal energy usage fee was 220,000 yuan. Better economic benefits have truly achieved the goal of reducing emissions and increasing efficiency. Although the system increases the power consumption of pumping chestnuts and pumping chestnuts, the cooling tower's power consumption is also reduced after the cooling water volume is reduced, and there is basically no new power consumption.
The use of waste water for waste heat utilization has also achieved good environmental benefits. Firstly, the cooling water volume of the cooling tower is reduced, the amount of drifting water and sewage is reduced, the water consumption of the blast furnace ironmaking process is reduced, and water resources are saved; secondly, the environmental condition of the blast furnace area is improved by heat recovery, and the heat of the slag water is reduced. Pollution can effectively reduce the heat island effect of the plant.
Wang Hao Cao. Design manual for water supply and drainage in the iron and steel industry. Beijing: Metallurgical Industry Press, Wang Haifeng, Zhang Chunxia, ​​Qi Yuanhong. Current status and development direction of blast furnace slag treatment and heat energy recovery. China Metallurgy, 2007.6. Application of blast furnace slag water waste heat heating. Shandong Metallurgy, 2003.01. Work.
Within the scope of benefits.
Energy equipment management work.
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