Boiler Help

[CraftBeerIndia]

Howdy,

We've got a Columbia MPH60 and its a real power house of a boiler, probably oversized for our application, 1 30BBL kettle (bottom and side) 1 90BBL HLT (side only), and 1 30BBL MT (side only)...I can provide exact heat transfer area if someone out there wants to get real technical...but I'm assuming at over 2 million btu's that we're fine with capacity.

Now, I am having a sluggish time getting up to boil. I am assuming that the standard temp rise is 1ºC per minute...we're getting about 0.10ºC per minute.

The pressure in the boiler is cut off at 1 BARG (14.7psi) and then it is unregulated into our process vessels.

Now, from a few previous breweries working experience, the boiler built up pressures to 30-45 psi and then there were pressure regulating valves before the vessels that were asking demand. These boilers were also termed "low pressure boilers" even though they were set at building up pressures above 14.7.

My argument to my bosses (and perhaps incorrect) is that the vessels will not get 14.7psi very quickly if the boiler is only producing 14.7psi, loss in pipelines, etc...

Then the contractor tells me that it is code and that we are only allowed to use low pressure steam boiler and therefore boiler cannot be set above 14.7psi. My reply is that the terminology of a "low pressure boiler" has to do with the size/capacity of the internal coil for that classification...ie a low pressure boiler can still produce 30-45 psi so that we can have adequate supply of 14.7 psi at our vessels.

So, i'd like to increase the set point on the boiler up to say 30psi (and change the safety valves to allow this), and then have pressure reducing/regulating valves at the vessels set at 14.7psi.

If this is a faulty logic, then my other possible explanations are that there is no bypass on the kettle steam piping and there may be water logged in the jacket thereby reducing the heat transfer surface and causing long times to reach boil.

Last possible reason is that there is no moisture separator in the supply line so the steam being supplied to the vessels is "wet" and therefore less steam heating capacity.

The vessels are CIPed regularly and no visible scale or physical reason why jackets should be underperforming. We've got the right boiler. I think the piping is ill-conceived or the set point needs to be adjusted.

Any tips or suggestions or reality check would be appreciated.

Thanks!

[dick murton]

I think you need to talk to a decent heating engineer. maximum demand for wort boiling is normally the actual boiling process, so you want the latent heat of evaporation from 100 C as water to 100 C as steam, whatever that is for your wort volume and % evporation. If it can do this, then it will eat the heating up as you should be heating up as you run the wort off, getting to boiling point as you finihs runoff, but this requires far less energy than boiling.

If you can't even heat up then you won't be boiling properly.

You want saturated steam to relesse maximum thermal energy as it condenses


But I will let someone else do the maths

Heat transfer will depend on the temperature differential between the steam and the wort, and surface area, and to a lesser extent, the exact thermal transmissivity of the heating tubes, but certainly fouling will hinder heat transfer.

[Starcat]

Some things to check

It will always be helpful if you use American units of measure rather than metric when dealing with American Tech people.
So Boiler Horsepower, PSIG, F, and so forth.
The fact that people are enamored with metric terms in this forum is another discussion, and one that is good for a few beers and more than a few laughs.

The boiler Manufacturer can tell you the design rating of the boiler. I have worked with 3 classes: 0-15 PSI, 0-50 PSI and 0-100 PSI.

I have run 50 PSI boilers at lower setpoints when that was the need. You can run more load at 45 PSI if you can get the heat transferred to the meduim.

A 20HP 10 PSI boiler should handle a 15 barrel system with no problem as example.

A 15 PSI boiler of correct HP should handle a small brewery without any problems.

Wet steam is not your problem.

The code reference sounds unusual.

You never change a relief valve rating beyond what the unit is designed for as specified by the manufacturer..

If the boiler is oversized for the load as you suggest then it should have no problem keeping up IF you are transferring heat to the kettle.
If the boiler is not fully loaded then it should be able to maintain pressure with no problem and notable off cycles.
If the boiler is overloaded it may not maintain setpoint, you will have lots of condensate return, and possible condensation from the fire side depending......
If you have bottlenecks or misdesign in your steam piping and return system, you will not have correct performance.

You must have a servo [ steam solenoid ] that will allow the correct mass flow to your jacket system. I have seen these incorrectly selected and they will essentially throttle the flow on the outlet compared to the correct unit.

You need a clean wye strainer ahead of the servo with a blow down valve on it so you so see and test what is coming through at regular intervals.

You need a properly sized and correctly working steam trap with a blowdown valve on the bottom to clean it out.

You need a blow down valve on the steam header that connects your jackets so you can test for live steam when your servo is active.

Gauges are helpful at key points in the described array so you can develop a visual of how things are when the system is " normal."

The suggestion that things are done by the numbers is correct. AS thus your boiler engineer and your kettle engineer can meet up on the steam criteria and BTUs.

If the system formerly performed correctly, then it is a matter of troubleshooting.

Sincerely

[dick murton]

"The fact that people are enamored with metric terms in this forum is another discussion, and one that is good for a few beers and more than a few laughs."

Warren. The reason people use metric terms is because, obviously strangely to yourself, more of the world use metric that imperial / US "imperial" terms, and there are increasing numbers using this forum who are not based in the States.

The other really awkward thing is that for some reason, US gallons, barrels etc are for some reason, different to UK imperial terms, which adds another level of complexity when referring to volumes etc - I know someone who ordered what he thought was a UK barrel brewery, and he got a US barrel brewery - much smaller than intended. I am never sure when our European friends talk about barrels whether they are talking US or UK barrels - so at least metric has the benefit of standard language and volumes etc.

So I agree with the comment that it is best to be clear which terms you are using, but suggest that there might be input from others outside North America who might have some input - a bit of a problem for one group or another if the query is expressed only in one set of parameters.

However, putting that to one side, I am not going to dispute anything you have said in general terms - I wouldn't dare as I don't have those skills - so thanks for the input.

[liammckenna]

Howdy,

Now, I am having a sluggish time getting up to boil. I am assuming that the standard temp rise is 1ºC per minute...we're getting about 0.10ºC per minute.

Thanks!

At the risk of sounding less than helpful, make sure your steam traps are functioning, make sure the steam (unlike glycol in fermentors) enters through the top of the jackets with condensate leaving the bottom. Make sure you have bleeder bypasses so you can vent any air locks out of the line before live steam. You can also get steam traps which will do this for you.

Best of luck,

Pax.

Liam

[gitchegumee]

Your heating tech is right. Low pressure boiler = 14.7 psi MAX. You should never, ever, ever even think of changing overpressure relief valves (or anything else for that matter) on a boiler. Piping losses will be insignificant if designed right. You should have at least 1" steam pipe to your kettle. As well as all the other devices described above, I'm a big fan of air vents (sometimes integrated into the steam traps) and vacuum relief devices. I agree that you should double-check the components are designed for the flow you require. Also highly suggest that you take apart the steam traps and clean them. Ensure they work by installing a sight glass post steam trap to ensure liquid (not gas) flow. You won't have much (if any) water in your jackets if they are designed right and if you have them plumbed right and if your traps work. If you've ensured that your lines are open to steam flow and that your traps work correctly and that your boiler steam pressure is 1 atmosphere at the kettle, then you will have heat. Good luck!

[samhuff]

+1 on the steam traps, if they are not functioning correctly, you will build up condensate in the system and lose efficiency.

As for the rest, what code are you referring too? I deal with most of the codes for boilers (ASME, ASTM, ANSI, API, etc), so I can see what I can find. The easiest way to figure out what you are deailing with is to look at the nameplate on the boiler. That will list your MAWP, design pressure, temperature, HP, flowrate, heating surface, etc.