Pressure Drop In Tubes

Scale buildup on the ID of your pipes.

What is Flow rate of water at outlet?

You kidding right? What goes in comes out unless there is a leak!

Of course.

Well, there is the issue of volume reduction of water as it cools.

OP should be able to solve this. He's got the numbers.

Mass flow should not change but the volume flow!

Knock knock! . . . !

I hope that's not the NSA!

Who's there?

If this is real life I would start with the sensor calibration.

One would expect a drop in pressure and temperature but if you are surprised by the numbers the numbes maybe wrong.

• Either a valve in the line is almost closed, or
• there is horrendous scale build-up in the pipes, or
• there is a lump of wood/dead fox/dustbin lid blocking the flow, or
• one or more of the measuring instruments is showing the wrong reading, or
• some other inadvertent restriction to flow not shown on the P&IDs

There is no way that 9 bar is being dropped through clean tubes that number/that diameter/that length with the average velocity so low. So it's time to use boroscopes and/or start pulling the plant to pieces to find out what is wrong and correct it.

• Been there, done it, secondhand T-shirt on eBay: the last time that happened here, the nut inside the gate on a reinstalled, "previously-enjoyed", 4in gate valve on a new chilled water line was so worn that it was no longer engaging with the threads and being lifted by the spindle as it turned. The solution was to replace the valve and stop being such a meany-knickers.

The numbers 28 and 27 imply a single circuit about 80m long, including the U-bends. The flow equates to about 60 gpm in a 2.5" pipe, which is reasonable. I am inclined to agree that there is some obstruction such as scale, which would have a tendency to accumulate at the U-bends.

What was the pressure drop when the plant was first commissioned?

What is the design pressure drop?

If there is scaling inside the tubes/bends, it will effect heat transfer, if pressure drop also it will have small effect.

Fluid flow at eco inlet is 15ton/hr

As im unable to visit the site, so work has been assigned to production deptt, they will sort out,

Thx

Do let the forum know what the problem was, for it will be interesting to many readers.

It appears that we are not speaking of a boiler economizer. Usually in a boiler economizer, the boiler feedwater is being heated up at high pressure. In some Heat Recovery Steam Generators, there is a boiler feedwater control water on the downstream side of the economizer path, to control admission to the steam generator sections.

In your case, it appears this is the primary side of a heat exchanger that is providing heat to another part of process, or is dissipating heat to a fluid, perhaps a reactant entering the process. IF there is any possibility of insoluble matter coming out of solution, then this could be where it is taking place.

Without further information about process, or without a complete shutdown with borescope inspection, there is nothing else to be said.

Maybe the on-site production department has someone capable of performing the calculations.

Well, wouldn't that have been the best thing to do in the first place?