how do i get bar pressure in a steam jacketed cooker 4

[weeknight]

Hi Guys,

I am looking for some tips on how i can build pressure in a jacketed sugar boiler. My boiler is rated at 700kpa and i am running a 35mm pipe directly to the cooker, the cooker is double jacketed copper, rated to 260psi, it has a pressure regulater attched to it rated to 16 bar, my problem is that i run the boiler up to 700 kpa, tur the valve to the cooker on full and get maximum pressure of only 2 bar in the cooker, i am doing my head in on this and it is probably something simple that i am missing. If anyone has any suggestions i would appreciate it. I should also add that i removed this cooker from a factory that was running it successfully, the only thing that i can think of is that i should run a bigger pipe from the boiler to the cooker?? I don't know.

Hope you can help weeknight

 

[rmw]

Are there any diagrams or pictures? Something is missing among the details of how this works (like is the boiler close-by, in the next room, county?

How is the jacket drained or trapped?

Are we talking about a toy, or a jacketed vessel from a sugar factory?

rmw

 

[weeknight]

Hi Rmw, Thanks for your feedback, ok the boiler is situated approx 10 meters from the cooker, and i should inform you i an based in victoria australia and i have very little resource to draw on so i appreciate any incoming thought. Anyway the cooker is an old one, justus theegarten twin pot vacuum cooker circa 1960 but in good nic, german manufacture and i can place photos online if it helps. My thinking is that the main steam pipe from the boiler is not big enough to create enough pressure to the cooker, when i pulled the boiler from an ind laundry it was running an output pipe from the boiler of approx 2inches, when i recommissioned i used a 35mm pipe and maybe this is the issue. The steam traps are as is when i pulled the cooker from it's previous position. The twin pots are made from copper and tested to 260 psi and i cannot get anything like this, so am keen for some input. Th anks for your help.
best regards weeknight

 

[hacksaw]

Basically the kettle is condensing steam at 134 C, so your gage pressure is 2 bar. That is normal for steam kettles. Your delta T beween the condensing steam and the liguid contents is due to the heat transfer coefficients.

Going to higher pressures is not going to help you that much gien the fact that your valves are delivering under choked flow conditions, also pretty normal.

The usual problem is inert gas in the kettle jacket interfering with condensation.

 

[weeknight]

Hi Hacksaw,

Thanks a lot for the info, i was wondering how i resolve this problem, you see when i load sugar to the pan it just stews and takes ages to get to temperature, if the problem is inert gas in the jacket do you know how i can alleviate this issue? Really appreciate any feedback,

regards weeknight

 

[hacksaw]

perfect description of a kettle cooker,

there are steam trap designs that help remove or vent the inerts, you can also manually vent them

once condensation starts and the condensate removal is okay, it should heat right up.

once you sort out getting good condensation, the heatup rate is limited by the piping and valve restrictions and condensate removal, rather than the pressure.

if the traps don't get rid of the condensate fast enough, condensate removal pump may be needed.

 

[weeknight]

Hi Hacksaw,

Thks for the message, ok i ran the cooker twice and manually vented the condensate, there is an isolation valve between the jacket and the steam trap, so i ran the condensate out until there was pure steam. The kettle heats up but still no pressure and the heat is only minimal, i was wondering if my problem is due to the size of the pipe i have running to the cooker, you see i am running 35mm black steel for 7 metres and then i run it into 1 inch copper to feed both pans, do you think i should upgrade the 35mm to 50mm, i wonder if this would make the difference. Please let me know what you think if you have time.

best regards weeknight

 

[hacksaw]

1. you need insulated feed pipe

2. the kettle will only condense as much steam as it can get
valve size can be an issue, look up valve capacity (some regulators use tables) or calculate the steam flow through the valve.

3. your maximum solution temperature will fix the jacket pressure,
100 DegC solution -> about 2 bar (or less in the jacket)

4. make sure the the jacket has good condensate removal to avoid flooding

you are only getting about 100 kg/hr through your pipe, at best, that is not a lot of steam.

 

[racookpe1978]

Have you checked your pipes - Condensate side AND steam delivery side? Are they actually clean - or clogged up with 60 years of corrosion and gunk and bugs and sediment and lime?

Ate your valves clean internally? When did you last take their bonnets off?

Is your tube (heat exchanger) actually passing steam? (Can you pass a rod or stiff wire completely through the steam HX from end to end? If you pass clean water in the inlet, what does the outlet look like, and how long does it take to drain the tubes? (If the water does not flow out immediately, or if the water only slowly stops draining out when you turn off the inlet, then the tubes are extremely dirty.)

 

[hacksaw]

@racookpe1978

kettle boilers are typically floor mounted vats, steam jacketed.
they have all the concerns you've raised, especially the need for inspection given the copper construction and the potentially corrosive nature of steam having unknown quality.

 

[weeknight]

Hi Hacksaw and Nuclear,

I have to say i really appreciate your feed back, based on your comments hacksaw i may have a problem with steam pressure, my old man was a director for gould pumps in the Philipines up until last year and i ran it past him, his view was that i might be losing pressure from the boiler to the cooker. I can't argue with this although i find it a little strange as i am only running a 35mm pipe for 7 meters and i might add it is completetly lagged with the good (expensive material). The guy i bought the cooker from was running a new boiler at 7600kpa with the same running gear so i don't know what i am doing wrong. Thanks also Nuclear for your input, what you say makes all the sense in the world, the only issue for me is that i purchased the boiler, yes and old tomlinson, but in good nic, clean ready to produce steam and fitted brand new pipes to the cooker, s far i have not checked the inflow valves for their performance and the reason why is that i was in the factory before the decommision and observed the cooker working with no problems. Just wondering if you guys think that that it would be worthwhile for me to break down the infeed to the cooker and give it an overhaul. Do you think it is steam pressure that is attributing to my problem, if you are suggecsting pipe constriction then for me it follows that you are suggesting steam or pipe pressure, i am no expert but i do welcome your comments.

best regards weeknight

 

[hacksaw]

what temperature do you want the contents to reach?

 

[weeknight]

Hi Hacksaw,

I need to reach 150celsius. I am cooking 35kg of sugar in each batch and am looking for a 25minute time window to cook each batch then i drop it down to a vacuum chamber to draw out any residual moisture.

best regards weeknight

 

[hacksaw]

so you've got steam available at 700 kpa(g) (sat. temp: 170DegC), and you want heat you liquid from sat 20 DegC to 150 DegC without carmelizing and in minimal time.

That is going to be tough.


The maximum jacket pressure is controlled by the wall temperature of your kettle, so even when the liquid has reached 75 DegC(with est 25 DegC delta-T through the wall and condensate film ) the pressure in the jacket is going to be 0 bar

Liquid Jacket Pressure
75C 0 barg
100C 1.15 barg
125C 3.50 barg
150C 7.50 barg

the problem is going to be limited heat-up rate. This is a common problem with all steam jacketed kettle cookers.

the kettle project I ran had four S.S. kettles with agitation and pumped condensate removal. The managers wanted 15 min heat up time...they got 45-60 min to bring the contents up to 100 DegC.

To get the heat up times required, needed 6000 kg/hr (each), but the kettles would only condense 1100 kg/hr (each)with the given steam valves and piping.

To get the heat up required, took a new boiler, new piping, noise abatement, all in an operating food plant, with Class A's once a week... they settled for the heat up time they had...

To get the temperatures you need in the time frame required, may require as pressurized kettle running at 1-2 bar.


good luck with you project

 

[GenB]

1- deleted...
2- replace regulator by installing a solenoid and pressure switch kit directly to the cooker. (pressure transducer works better), switch or transducer will control a solenoid valve to start-stop the incoming steam.
3- on the cooker side be sure to install a safety relief valve limiting the amount of steam pressure.(15% over the desired max. steam pressure in the cooker)
4- install a vent valve to relief air and/or gasses on the cooker.
5- install avacuum breaker to save your cooker of collapsing under vaccuum.
enjoy the sugar...

 

[MikeHalloran]

Be very careful about increasing the jacket pressure in a jacketed vessel; you could easily collapse the inner chamber/pot/bucket. The collapse is due to buckling of an externally pressurized shell, and happens instantaneously. ... i.e. with expulsion of hot sugar out the top, all at once. You will not be happy with the results.





Mike Halloran
Pembroke Pines, FL, USA