Does a Small Footprint, High Flow Rate, Low Capacity, Steam Accumulator Exist? 1

[RamWreck]

Hello everyone,

I'm looking at sizing a steam accumulator for an application that has very high instantaneous flowrates (1800 kg/hr) of saturated steam for ~ 15 seconds followed by no steam requirement for 35 minutes. Total steam flow is something like only 7.5 kg over that 15 s. This is obviously a good application for a steam accumulator, however, this application has very tight space requirements (packaged skid). Normally, or at least what I have seen for the most part, is that steam accumulators generally need to supply a large volume of steam but the flowrate requirement is not so much more demanding relative to the total capacity required (or at least compared to the process I am working with). Since the surface area of the water in the accumulator is the primary factor in the flow rate and the volume of water is the primary factor in the total steam capacity, I am looking at needing a vessel with a very large surface area but not a lot of volume. This could essentially be a pipe (maybe 8") that is maybe 15' long. This is not great considering the space constraints, and it would be preferable to use a vessel with a length/diameter ratio that is not so skewed. I could oversize the diameter of the steam accumulator, i.e. give it more volume than needed but this seems unnecessarily wasteful considering the space constraints on the skid. It seems I could benefit if there were such a vessel that had some sort of atomizing nozzles that recirculated the water, or if the vessel were packed with a media that could increase the surface area of the water such as cooling tower-style media while recirculating the water over it. My question is, if such a thing exists or if there are manufacturers that specialize in the design of custom steam accumulators such as what I am describing?

Thanks!

 

[crshears]

Have you checked out the following section

https://www.spiraxsarco.com/learn-about-steam/the-boiler-house/steam-accumulators

of the Spirax/Sarco website?

[Note: I have no dealings or affiliation with them.]

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[RamWreck]

Yes! It's a great article but it doesn't discuss anything about the situation where you need to maximize the water surface area but only require very little total water volume. This might be such a unique issue that there isn't really a market for such accumulators. As I mentioned you can solve the problem by just oversizing the steam accumulator volume to get the required surface area but I'm working on an equipment skid that is very tight on space. Although it seems very possible to design a steam accumulator with a high water surface area (cooling tower/wet scrubber) I just don't have experience with this and was interested to see if there are manufacturers who have equipment already like this or who are capable of doing a rigorous design of such a vessel.

 

[FacEngrPE]

Steam accumulator can be either of these
[ul]
[li]a tank partly filled with water where the water boils on reduction of pressure, and then needs to be heated to saturation at the desired starting pressure.[/li]
[li]A unfired pressure vessel filled with steam.[/li]
[/ul]
in both cases the physics of the energy storage will determine the volume needed. If you need dry steam the skid may also require a moisture separator.

https://sugartech.co.za/steamaccumulator/index.php

thread794-14016

https://industrialsteam.com/wet-steam-accumulators/

 

[RamWreck]

Hey thanks for the response, FacEngrPE. I understand the difference between a dry steam accumulator and a wet steam accumulator. My problem is not about having enough energy storage (volume) but how can I get a high enough evaporation rate from a wet steam accumulator without having to rely on the surface area in a horizontal cylindrical vessel as this causes the volume of the vessel to be way larger than I need.

 

[FacEngrPE]

The physics of fast response to a step change in steam demand is the same for a boiler and a steam accumulator. As the pressure drops the bubble fraction in the water increases, you can work out the details from the steam tables. Once the bubbles form they need to rise to the surface. In the extreme case the boiler or accumulator will foam, resulting in carryover.

In either case the steam is saturated, and if dry saturated steam is needed then either a significant volume is needed for the fog to settle out or some sort of mechanical separation is needed.

You could put a mechanical separator inside the accumulator similar to what is seen in a fire tube boiler,

or you can use a separator in the discharge line

https://wright-austin.com/tseparators/R-separators/RSEPARATORS.html

These devices claim the ability to remove fog from steam to 10 microns.

Internal elements are available

https://wright-austin.com/products/Internals60-70I.html