Problem of the drum pump not delivering sufficient flow
Thread Content
Our factory uses dry coke to produce hydrogen, but the steam drum pump isn’t able to deliver enough flow. So we added another pump, yet sometimes even with three pumps in operation, the required flow isn’t achieved. According to some information, the operating conditions for the deaerator are a steam pressure of 20 kPa and a temperature of 104°C. In that case, should we install a cooler between the steam drum and the pumps? Our factory simply cannot reach such high temperatures, which means the deoxygenation effect cannot be achieved. How should this problem be solved? Thank you
When the deaerator operates at a temperature of 104 degrees, as water enters the pump’s suction inlet, it vaporizes due to reduced pressure; in effect, this is gas entrapment in the pump! Using an additional pump in this case is definitely of no use. How about you lower the deaerator temperature, at the expense of the equipment at the back? ； Otherwise, you need to find a way to increase the pumping head pressure in order to raise the pressure in the deaerator.
What was said on the 2nd floor is correct; the inability to pump fluid is definitely due to a pressure issue, and replacing the pump is also an option
As long as the installation height is sufficient, the drum pump will not suffer from air locking. The operating temperature is usually around 102–104°C, and there are no issues with operation!
I asked people from other refineries, and their deoxygenated water is sent directly from the power unit to the steam drum; at a pressure of 20 kPa, the temperature can reach 104 degrees. Our factory doesn’t have deoxygenated water for use as power source; instead, we have a deaerator, but the temperature there simply isn’t high enough. If the temperature were high enough, it would be easy for the water pump to fail to deliver the required flow rate. As for increasing the pressure, that wouldn’t allow the water to reach its saturation temperature, meaning the deoxygenation effect wouldn’t be achieved either. Although it might ensure that the pump can deliver a certain flow rate, doing so is equivalent to lowering the temperature.
Solutions to the problem can be considered in terms of pump selection, installation location (especially the layout of the inlet pipes), and operating temperature. I think for the phenomenon you mentioned, it is necessary to improve the pump’s resistance to vapor locking, and to minimize the length and number of bends in the inlet pipeline.
Preliminary findings: 1. The quality of the pump is substandard; more precisely, the material used for the pump is not suitable； 2. Cavitation in the pump causes damage to it, rendering it unusable ； Possible solutions: 1. Replace the pump material with 316L. 2. Reduce cavitation: a. Increase the pump’s suction height while enlarging the diameter of the pump inlet pipe ； (The inlet pressure of the boiler feed water pump should be maintained at 0.1 MPa.) b. Increase the pressure in the deaerator ；
1. The deaerator in the hydrogen production plant operates under conditions of 20 kPa and a temperature range of 102–106 degrees; the operating conditions are fine. 2. Unless power can be supplied directly to the deoxygenated water, it is not necessary to lower the temperature – deoxygenation is essential. The pressure also cannot be increased arbitrarily, as there are limitations imposed by the deaerator itself. 3. It is not feasible to add a cooler between the deaerator and the pump; there is no need to incur such extra energy costs. 4. It is not necessary to use 316L material for the feed water pump. If the user provides the model of the pump, an analysis can be done from that perspective. In the design parameters of the feed water pump, the inlet pressure is at atmospheric pressure, and the temperature is also within the range of 102–106 degrees; it’s worth checking whether this is the case. Is the diameter of the inlet pipeline sufficient? What is the vertical distance between the deaerator and the pump? These are likely the main reasons.
Check whether the flow control orifice plate at the pump outlet leading back to the deaerator is clogged. If the steam generation volume of your drum is low, and the drum feedwater valve remains closed or operates at a low flow rate, the water inside the feedwater pump may vaporize, resulting in the pump running without sufficient liquid and failing to deliver the required flow rate.