Marsbars2319
Member
Hi everyone, I am an electrical engineering intern who recently received a project that is definitely a bit over my head, and I could use some help. I am tasked with redesigning and implementing a new control system for the main wastewater lift station at our plant. The current system in place is inadequate and failed recently causing an overflow. It currently uses several mechanical float switches and is not wired or programmed to be very fail-safe or redundant.
The goal of this redesign is to replace the mechanical float switches with something that requires less maintenance and is much more reliable/less likely to fail. Along with that I am also supposed to build the system to be much more redundant, whether it be through multiple redundant sensors, wiring, programming or all of the above. This is a very important system, and an overflow is obviously very undesirable, so money is no object in this project.
Some information about the system, the lift station is located outside of the plant, is a circular, concrete pit, 8 feet wide, around 17 feet deep. It has 3 pumps at the bottom. Inflow averages 1200 gallons per minute, and it has a volume of approximately 10,000 gallons. As far as the liquid goes, PH can range from 2 to 12 (mostly stays on the caustic side). It is turbulent, with foam a possibility, I would say less than a foot. Temperature can come in at 112 degrees Fahrenheit. Vapor is also a concern.
My first and main question/task to figure out, is which type or types of level sensors to use to do the monitoring. From my own limited research, based on the conditions of the lift station, the two best options seem to be guided radar, or hydrostatic pressure. If you could provide some guidance on which would be the best and why I would appreciate that.
The next concern is how to make the system redundant, so failure of one sensor does not cause an overflow or cause the pumps to run dry. The main idea now is to perhaps run 2 analog sensors, and program them in the PLC to compare the values and check the tolerance on them. Also perhaps leaving a high-level float in the system as the backup. I would also appreciate some feedback on the best way to do this as well.
Any and all help is welcome, if you have any other advice on this project please do share. Too clarify i won't be doing this by myself, I will have the help of senior electrical engineers, I am just trying to help and do as much as possible myself.
The goal of this redesign is to replace the mechanical float switches with something that requires less maintenance and is much more reliable/less likely to fail. Along with that I am also supposed to build the system to be much more redundant, whether it be through multiple redundant sensors, wiring, programming or all of the above. This is a very important system, and an overflow is obviously very undesirable, so money is no object in this project.
Some information about the system, the lift station is located outside of the plant, is a circular, concrete pit, 8 feet wide, around 17 feet deep. It has 3 pumps at the bottom. Inflow averages 1200 gallons per minute, and it has a volume of approximately 10,000 gallons. As far as the liquid goes, PH can range from 2 to 12 (mostly stays on the caustic side). It is turbulent, with foam a possibility, I would say less than a foot. Temperature can come in at 112 degrees Fahrenheit. Vapor is also a concern.
My first and main question/task to figure out, is which type or types of level sensors to use to do the monitoring. From my own limited research, based on the conditions of the lift station, the two best options seem to be guided radar, or hydrostatic pressure. If you could provide some guidance on which would be the best and why I would appreciate that.
The next concern is how to make the system redundant, so failure of one sensor does not cause an overflow or cause the pumps to run dry. The main idea now is to perhaps run 2 analog sensors, and program them in the PLC to compare the values and check the tolerance on them. Also perhaps leaving a high-level float in the system as the backup. I would also appreciate some feedback on the best way to do this as well.
Any and all help is welcome, if you have any other advice on this project please do share. Too clarify i won't be doing this by myself, I will have the help of senior electrical engineers, I am just trying to help and do as much as possible myself.
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