Weak current College】 【pump speed control system failure analysis --- Power By】 【China power house network.

<br> General boiler feed water pump with speed control devices, such as hydraulic coupling, etc, is based on the unit load changes to adjust the pump flow, reducing losses, thereby saving energy conservation. <br> <br> Hydraulic coupling speed .pump (hereinafter referred to as liquid transfer pump) run time, you should be able to input the automatic adjustment to reduce the operating personnel of the operation, its speed range should reach 25% ~ 100%. But some liquid transfer pump exist speed rate ., causing traffic fluctuations that may cause broken shaft accidents. <br> <br> A power plant to the pump by front pump, main pump, hydraulic coupling and speed gear. Front pump motor spindle drag, main pump motor through speed gears, hydraulic .coupling drag. Front pump model for QG50080, main pump model for DG480180, hydraulic coupling model C046, Shanghai electric power building and repairing factory products. <br> <br> 1, fault conditions <br> <br> The liquid transfer pump after .a repair operation, automatic adjustment of characteristic found water supply variation. Vote automatically, there is flow fluctuation, sometimes reach 80t / h, seriously affect the normal operation of the unit. For the analysis of this issue, the normal pump control system switches to .fault pump, has the same problem, which essentially eliminates the thermal control reasons. <br> <br> 2. feed pump hydraulic coupling of regulation <br> <br> The 1990s, hydraulic coupling in the country for fast development, constant speed .feed water pump of throttle modulation, effectively saving power. <br> <br> Hydraulic coupling of regulation is regulated by spoon tube turbine oil drainage capacity to adjust to the pump speed, so as to achieve the purpose of regulating the flow. Flow q .change and speed proportional to n. <br> <br> According to the pump performance curve, you can make a flow of relative value g and spoon tube relative angular displacement L curve. <br> <br> g = G / Gmax ( .1) <br> <br> Type: G-pump output current capacity, t / h; Gmax to pump maximum output current capacity, t / h. <br> <br> μ = α / αmax (2) <br> .<br> Type: A-spoon of angular displacement; Amax for the spoon pipe maximum angular displacement. <br> <br> K = dg / dμ = αmax / Gmax · dG / dα (3) <br> <br> K .is the slope of the curve, ie a zoom factor or adjustment coefficients. <br> <br> In an ideal State K = 1, ie the angle to 45b, hydraulic coupling in speed adjustment process flow smoothly, no adjustment and mismatches between the .flow. <br> <br> When the 1 K, flow change slowly, is not conducive to track load adjustment needs. <br> <br> K, 1, flow change too quickly, easily cause flow fluctuations and resulted in the drum ., pump control frequently, may result in axle fracture. <br> <br> 3. liquid transfer pump performance test <br> <br> To find the cause of the failure, on the characteristics of the pump, adopt the General test method .. Test before checking the meter. <br> <br> Test by liquid transfer pump boost pressure after the water supply to the extent possible, through flow orifice to decreased pilot error. The reduction of water use, and give the appropriate amendments. On .this basis of any relevant data. <br> <br> 4, fault analysis <br> <br> Test, manual operation, there is no spoon flow fluctuations, current stable, balanced pressure normal, explains run-off shaft does not exist .. Motor works, hydraulic coupling in the load points run correctly. According to the needs of load adjustment, whenever operation manual operator, traffic, great changes have taken place, to control the flow of the request, the more difficult. Spoon tube journey from .61mm changes to 71mm, flow from the change into 284t / h 430t / h. You can see, the entire control system for linear better but steeper curve, opening each variation 1% flow change 11.23t / h pump flow, determined by the speed .of feed water pump. Pump mounted to the hydraulic coupling of turbine and the turbine speed determined by spoon pipes back to oil. If the unit stroke within the oil change too much, would seriously affect the stability of the water pump flow. To this end ., should reduce the spoon pipes back to oil change rate. <br> <br> 4.1 amplification coefficient K <br> <br> Spoon pipes of maximum stroke to 110mm, maximum flow to 440t / h, the flow changes from 284t / h .to 430t / h, itinerary changes from 61mm to 71mm. <br> <br> K = dg / dμ = αmax / Gmax · dG / dα = (110/440) · [(430-284) / (71-61) .] = 3.65 <br> <br> The inclination of the curve, for 74.7b steeper curve, this is caused by hydraulic coupling speed performance instability. To improve hydraulic coupling tuning performance, it is necessary to solve the spoon pipes back to oil change ., makes the same opening variation of conditions, back to reduce the quantity of oil. <br> <br> 4.2 cam <br> <br> The demolition of old cam after reinstalling, commissioning, found on hydraulic coupling performance improvement is not clear .. To this end, plus the cam at the same time, change the cam to adapt to the needs of load regulation. That is, 50% load following, so that the cam is steep; load often adjustable interval, cam flatter; the remaining .load interval of a steep curve. <br> <br> 4.3 reduced rack and pinion gear ratio <br> <br> Hydraulic coupling regulation, cam-driven rack up and down, rack and then driving gear, gear then led fan gear, .thus giving rise to spoon tube opening change, regulation of water flow. Spoon tube adjustment is done by fan gear rotation to led, rack drive and sector gear coaxial gear. DecreaseRack and pinion gear ratio, ie increasing gear diameter, length, guarantee extension rack .tube on foot of the spoon and the gateway. Reduces the rack and pinion gear ratio, ie the same trip cam, fan gear for Aperture smaller, spoon of oil conditioning quantitative small, thereby reducing the water flow fluctuations. <br> <br> .5, approach and results <br> <br> According to the above analysis, to take the appropriate measures. First of all consider increasing cam, if you increase the cam is invalid, then consider using computer control. Increase the difficulty of the cam .is relatively small, easy to implement, and cam-type cables have been improved. According to the normal operation of the load unit interval, consider the following 50% load, the cam profile is steep; 50% ~ 100% load, the corresponding .profile is flat. In low-load or post process, because of the need to open the feed pump recycling valve, pump can maintain a high traffic. <br> <br> Then, restore the original cam on spoon tube itself without much impact ., spoon tube journey in (60 ~ 70) mm, slope still 3.45. Improvement through cam, the entire drive system (including manual operator) slope 100/440 · [(416-274) / (71-48)] = 1.4, .inclined to 540, dip a significant reduction in the basic met the needs of load adjustment, the modification of the unit is operating normally. <br> <br>.