Does anyone have experience with recessed impeller pumps?
Does anyone have experience with recessed impeller pumps?
I see other problems with the pump duties in regards to the flows and head especially service A - this will be a pump running well to the left on its curve (if you can find a small slurry pump with recessed impeller capable of this duty range), with such a turn-down you will probably get a lot of re-circulation within the pump resulting in accelerated wear of the pump.
You might have to re-think the application and the range of flow / head. i am thinking to spill back some of the fluid to the sump to maintain an operating point close to BEP for service A - the curves i've seen cannot provide the head and flows together for this service.
service A and B will be 2 separate pumps but in similar applications so turndown should not eb an issue - i should have explained that earlier.
still, i feel there aren't other designs that can work better than a recessed impeeller pump in this application. There are recessed impeller dredge pumps which might be able to handle a situation like this. The suction is literally inserted into beds of underwater sediments and it pumps them whole, including rocks up to about 3" diameter. It was many years ago when I heard of this thing and it was odd enough to remember it even now, but I have no experience using such a thing and I'm afraid that I don't have a vendor name to recommend.
I'm sure any pump you choose will wear, and lines or other parts of the system will still be subject to plugging by some wierd combination of solids of various sizes, stringy bits and glue (oil/grease). Artisi,
Many different designs were tried in these services in the past - diaphragm, piston, self priming centrifugal, vertical turbines. Back then, i was still in school but from the data i have, all these designs performed poorly with Mean time Between Repairs ranging from 3 months - 9 months. so the services were very maintenance intensive and costly too.
you have an excellent point about the re-pumping of sand. If i can get 3 - 5 years problem free operation with the recessed impeller design, I won't mind replacing worn components with this runtime. do you think this is a reasonable runtime for services of this kind or maybe too ambitious?
thanks.
It comes down to:
1. can you get a pump that is comfortable in operating at duty A and duty B. I think the first thing you need to do is locate a pump that is capable of the hydraulic duties.
2. If you can find a pump - then you need to look at material of construction options available.
An all metal slurry pump in 28% chrome should give you reasonable life provided it is within the hydraulic capabilities.
Warmans used to manufacture a cantilevered slurry pump - you need to check what is now available. Artisi,
I checked out warman. their recessed impeller design cannot provide the head for the services. they do have a couple designs such as the double suction seal-less open impeller which looks interesting. i don't know if you or anyone has any experience with that design. my concern would be the vegetation as there is a tendency to plug open impellers. At least thats what used to happen to the self primers we had before. thanks for you input again. If you have or can arrange for a reasonably clean water supply, you may want to consider a jet pump arrangement (probably multiple stage) for this duty. A jet pump system may use more energy, but by careful choice of materials and configuration, wear and plugging problems can be minimized or avoided.
Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered. If you have long stringy type vegetation reducing the width of the impeller blade to give more clearance between the impeller and the casing is one remedy, some rework to the blade shape can also help. This reduces pump hydraulic efficiency but, if it works without clogging then pump efficiency becomes 100%.
ITT Goulds who incorporated the Allis Chalmers pump business have an impeller from AC pump range called the Shearpeller, this allows large air-handling capabilities and and capacity to pump long stringy product with reasonable efficiency - not sure if Gouldss have a cantilevered pump rangs and if this impeller can be fitted - assuming they have such a pump.
Although I have no direct experience - Nagle pump company will probably have something to suit.
ccfowler,
i don't believe that we have the luxury of a readily available source of clean water. but, i will look into your suggestion and see if its practical.
Artisi,
the goulds designs i've looked at in their GPM catalog can't provide the head required for the applications. the shearpeller is a horizontal design i believe and won't be able to lift the product. i will send them a request for quotation. see if they have anything new that i haven't seen as yet.
thanks again to you both for your great advice.
Slurry Pump safe operating procedures
1. before the inspection
1) Check the direction of rotation of the motor is consistent with the direction of rotation of the pump (please refer to the corresponding model instructions). In the test motor rotation direction, should be a separate test motor, must not be connected with the pump test.
2) Check whether the elastic pad in the coupling is intact or not.
3) Check that the motor shaft and pump rotate concentrically.
4) handcart car (including motor) pump should not be astringent and friction phenomenon.
5) Check the bearing box to join the bearing oil to the oil mark indicating position.
6) Slurry pump should be started before the shaft sealing water seal (mechanical seal for the cooling water), at the same time to start the pump inlet valve, close the pump outlet valve.
7) Check the valve is flexible and reliable.
8) Others, such as anchor bolts, flange seals and bolts. Piping system is installed correctly, solid and reliable.
2, start running and monitoring
1) Slurry pump should be started before the pump inlet valve, close the pump outlet valve. Then start the pump, start the pump and then slowly start the pump outlet valve, pump outlet valve opening size and speed, the pump should not vibrate and the motor does not exceed the rated current to grasp.
2) series pump with start, also follow the above method. Just open a pump, you can end of the pump outlet valve to find a little (open size to a pump motor current rated current of 1/4 is appropriate), and then you can start two three Until the last stage pump, tandem pump all started, you can gradually open the last stage of the pump outlet valve, the size of the valve to open the speed, the pump should not vibrate and any level of pump motor is not over-rated current to grasp.
3) The main purpose of the slurry pump is to deliver the flow rate. Therefore, it is best to install the flow meter (meter) in the operation monitoring system to monitor the flow rate at any time. In the pipeline system with swirler, Filter press dewatering system also requires a certain pressure at the exit of the pipeline. Therefore, in this system should also be fitted with pressure gauge to monitor whether the pressure meets the requirements.
4) In addition to monitoring the pump flow during operation, pressure, but also to monitor the motor do not exceed the rated current of the motor. Always monitor oil seals, bearings and other normal phenomenon occurs, the pump takes place or overflow pool, etc., and at any time.
3, slurry pump routine maintenance
1) The suction pipe system of the pump is not allowed to leak. The grille in the pump chamber should meet the requirements of the particles that the pump can pass to prevent the blockage of large particles or long-fiber materials entering the pump.
2) To promptly replace the investment parts, repair and assembly to be correct, the gap adjustment is reasonable, no austerity friction phenomenon.
3) Bearing pressure, water to meet the requirements, at any time to adjust (or replace) the degree of tightness of the filler, do not cause shaft seal leakage. And timely replacement sleeve.
4) When replacing the bearing, be sure to ensure that the bearing assembly is dust-free and the lubricating oil is clean. When the pump is running, the bearing temperature should not exceed 60-65 Fahrenheit, and the maximum should not exceed 75 Fahrenheit.
5) To ensure the motor and pump concentricity, to ensure complete and correct elastic pad coupling, damage should be promptly replaced.
6) to ensure that the pump components and piping system is installed correctly, solid and reliable.
4, slag pump disassembly
1) Disassembly and Assembly of Pump Head Parts Disassembly and clearance adjustment of pump head parts should be carried out according to the assembly drawings.
2) Shaft sealing part The packing shaft should be disassembled and assembled according to the assembly drawing. In order to ensure the sealing effect of the packing shaft seal, the shape of the packing opening should be cut and cut as shown in the figure. When loading into the packing box, Filler openings should be offset 108 degrees loaded.
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