What causes the speed of a gas blower to increase suddenly after it stops operating?
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During the process of switching blowers (shutting down #2 and starting #3), due to human error, the normally operating blower (#1) was shut down on site. Subsequently, #2 blower was started urgently, but at that point the speed of #1 blower rose rapidly to over 4,000 revolutions per minute. The overcurrent curve was retrieved and showed a value of 0. Since the outlet valve of fan #1 was not closed in time, the following questions arise: (1) Was the increase in the speed of fan #1 caused by backflow of gas behind the fan? (2) Will backflow of gas increase the fan speed to over 4,000 revolutions per minute? (3) What harm does this situation cause to the fan?
It’s reversed; I’ve encountered this before as well
This post was last edited by 764970655 on 2016-11-14 at 11:52. 1. My understanding is as follows: at that time, the fans in operation were #1 and #2. During the process of switching the blowers (shutting down #2 and starting up #3), due to human error, the fan that was operating normally (#1) was shut down on site. At that point, fan #2 was still running normally. Since the inlet and outlet valves of fan #1 were both fully open, the pressure at the outlet caused its rotation speed to drop from normal levels to zero, before it quickly increased again to over 4000 revolutions per minute. At this point, the power supply to Fan 1 has been cut off, so the current is zero. 2. Will backflow of gas increase the fan speed to over 4,000 revolutions per minute? Of course it will, because the system resistance is greater than the bypass resistance created by Fan #1. The bypass generated by Fan #1 results in an extremely large circulation volume, which increases the fan’s speed to over 4000 revolutions per minute; at the same time, most of the covers on the rising pipes of the coke oven are pushed open, causing heavy smoke to emanate from the oven. This situation is immediately reported, and the environmental protection authorities impose a fine of 100,000! 3. What harm does this situation cause to the fan? After the fan stops, the high-level oil tank can provide lubrication for 10 minutes during idling; beyond this time, all lubrication points in the fan system will suffer from a lack of oil, leading to serious equipment failure accidents! :funk:
(1) The reason for the increase in the speed of Blower No. 1 is backflow of gas behind the blower. (2) Gas backflow will increase the fan speed to over 4000 revolutions per minute, yes. (3) Hazards of this situation to the fan: 1) If there are no locking mechanisms in place to secure the impeller cover, it may loosen, or even cause the impeller to fall off ； 2) Reduced blower efficiency ； 3) Incomplete combustion of fuel in the furnace leads to fuel waste, and flash explosions in the furnace may even occur later on.
No, the pipe is 1.8 meters long; installing a check valve would create considerable resistance. Moreover, this is an error in operation – it’s happened for the first time
It was a typo; 1# was written as 2#, but it has been corrected.
The reason for the increase in the blower’s speed is backflow of gas behind the blower. A check valve can be installed at the outlet of the gas blower.