Which pumps are typically equipped with automatic start-up for catalysis?
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Recently, I heard from the supervisor that for catalytic units, some important pumps are equipped with automatic start-up functions. For example, the deaeration pump that supplies water to the steam drum is equipped with automatic start-up. For automatic startup, there is the type where the speed does not decrease when the running pump loses power, as well as the type where a backup pump starts up after the running pump stops. Under what circumstances are these 2 types set respectively?
In our case, the lubrication pump for some large-scale units has self-starting capability; when the oil pressure of the operating pump falls below a certain set value, the backup pump starts automatically.
Generally, self-starting of boiler feedwater pumps is not recommended. 1. When one boiler feedwater pump is in operation, the outlet valve of the standby pump should be closed (although there is a check valve at the outlet). 2. The pump should be started first, after which the outlet valve should be gradually opened to prevent excessive current from damaging the motor； 3. Even if the water pump stops operating, the boiler water system has a certain capacity, so it will not run out of water in a short period of time.
We ran into this problem this time as well. First, two concepts must be clarified. Automatic start-up of pumps: This refers to the situation where another pump starts automatically after one pump becomes empty or fails to function; the determination is based on the pressure transmitter at the pump’s outlet. Therefore, self-priming pumps require a pump outlet gate valve to be closed, and the motor design must take into account the high current levels that occur when the pump starts. Pump restart: refers to the situation where the pump can start automatically after power is supplied again after it has been without power for 3-5 seconds. Also, a question regarding the 2nd floor: 1. When one boiler feed pump is in operation, the outlet valve of the backup pump should be closed (although there is a check valve at the outlet). What is the reason for this?
For large units such as the main fan in our installation, lubrication pump systems of this type are equipped with auto-start functions. Similarly, standby pumps are also set up for auto-start in our deaeration water pumps and hot water pumps. However, we are concerned that the high current generated during startup might cause damage to the equipment, so we have disabled the auto-start functions
Here, we set key pumps such as the crude oil pump, top reflux pump, middle section pump, crude gasoline pump, and unit lubricating oil pump as self-starting pumps. The self-starting function here is limited only to self-starting the pump in the event of a power fluctuation or loss of power.
4# chives “Pump restart: refers to the situation where the pump starts automatically after power is supplied again after a 3-5 second power outage. " Regarding the restart of the pump, I believe it only occurs during power fluctuations, and for this to happen the pump’s speed does not need to drop significantly. So 3-5 seconds were set. I’m not sure if there are any other situations.
The pumps that start automatically in our system include: the boiler feedwater pump (auto-start has never been used), the lubrication pumps for the four units, the lubrication pump for the air compressor, and the oil pump for the special valves. The special valve pump starts automatically as a backup once the main pump stops, while the unit lubrication pumps start automatically when the system oil pressure drops to a certain level
Our device automatically restarts within 3 seconds in the event of a power fluctuation to the main fan. Standby pumps for the main fan and air compressor lubrication pumps are configured to start automatically. For special valve pumps, I recommended setting up automatic startup of a backup pump, but the workshop did not accept this idea. Every time there is a power fluctuation, the special valve shuts down, posing a serious threat to the safe operation of the equipment. It is highly recommended that special valves be equipped with automatic pump startup.
9# For water longevity special valves, the backup pump should be equipped with an auto-start function; however, it wasn’t previously noticed that the main fan should also start automatically within 3 seconds in case of a power outage. I wonder if this current will be high?
The boiler feed pump I have is not equipped with automatic start functionality; the pump must be started manually on site. In contrast, the blowers and exhaust fans in the converter are equipped with backup units, such that when one of the operating fans stops suddenly, the other backup fan starts automatically. But we didn’t have a power fluctuation that caused the machine to shut down for three seconds before the auto-start procedure kicked in.