We currently have a 144,000 BTU hot water boiler, and a 1/25th hp circulator pump , and i've noticed it takes far too long to heat 1200 gallons of oil to even 150F (3 days).


This is my 1st experience ever dealing with a boiler, so I was thinking maybe the pump was too small to move the distances and drops needed?


I'd like to heat this oil to 220F , and within a day or so. If anyone can offer some insight into the mathematics or necessities i need to consider, I'd really appreciate it.


Thanks,
Ryan

that boiler should heat up that oil in hours not days. I would need to know more info like are you using the circulator as your pump for oil? Are you running the oil thru the boiler (hope not)?
Are you using a heat exchanger and what size? Is the 1200 gallon vessel insulated? How much insulation (thickness, type)? If this vessel is a large tank is it sitting on the ground,concrete and is that portion insulated?

Next 220 is a high temp for that boiler, that is the range of steam. Does your boiler have steam controls? Or is it set up for forced hot water, the fact that you mentioned a circulator would make me believe it is set up for hot water unless it's something you added yourself. Do you have any pictures of your set up that I can look at?

That should keep you busy! I will check this post again Monday am. What you want to do is easy to accomplish I think you may have made a few mistakes. But it's nothing that can't be fixed. Be careful with boilers you can get in trouble real fast.

To raise (increase) the temperature of 1200 gallons of veg oil 100 degrees (F) will require about 960,000 btu's of energy input.

Divided by 144,000, that comes to about 6.6 hours not counting thermal losses.

Thanks Murphy I didn't get a chance to do the math for him but I know I was close by telling him hours verses days. I think he's got his hands full right now.

I have beed considering this option. Can you use antifreeze in a boiler to raise the usable temperature or is other parts of the boiler susceptible to over heating damage. Does anyone have a formula to figure how large of a heat exchanger is needed for efficient thermal transfer

My burner heats the oil directly, it'll take 250 gallons to 140F in about 40 minutes, it evolved from murphys burner, the blue pump is no longer there, the main 125gpm process pump does the circulating now.

marvingvx

Actually antifreeze is a good option but depending on the boiler you can loose some efficiency in the heat transfer about 10 to 20 percent not a big deal for what your trying to do. But the anti freeze is a whole lot safer than running the oil thru your boiler. The biggest draw back to running the oil thru your boiler is if one of the sections ever cracked or you spring a leak between sections this would feed oil into the combustion chamber and create a huge overfiring with disaterous results.

marvingvx

To answer your question on heat exchangers a inexpensive exchanger that will work like a charm is a "shell and tube". If you surf the net for manufacturers they will list the output of there exchangers based on input. Also they would love to sell you one if your not sure of yourself they all have a tech. dept. that can help you size it for your application. They are available with SS tubes verses copper for a higher fee but based on past exp. you should expect to pay $300-$500 +/-

quote:

Originally posted by 51fitter:
marvingvx

Actually antifreeze is a good option but depending on the boiler you can loose some efficiency in the heat transfer about 10 to 20 percent not a big deal for what your trying to do. But the anti freeze is a whole lot safer than running the oil thru your boiler. The biggest draw back to running the oil thru your boiler is if one of the sections ever cracked or you spring a leak between sections this would feed oil into the combustion chamber and create a huge overfiring with disaterous results.

Not if the heat exchanger is built right, mine has a 6" tube with 1/8 inch wall on the inside, the flame is in this tube, the outer tube is 12" tube with 1/8" wall, in between the two tubes there is a helicle ramp the goes from the bottom to the top that forces the oil to travel round and round the inner tube about 20 times to the top where it exits, inside the flame tube there are half discs that cause the flame to travel a zig-zag up the tube, most of my heat is transfered into my oil.

Good point on the conventional boiler 51fitter! I was considering using one but I am now glad I decided on a steel boiler instead.
I will be building one this winter (hopefully if time permits!) based on Fabricators idea only mine is based on an oil fired hot water heater. I have cut the top 3/4 or more of the skin off of it and have a 30" piece of 12" X 3/8" structural steel pipe from a crane manufacturer for the outer boiler skin, its way heavier then I would have liked but the price was right! This will give me a much smaller volume in the boiler to try and keep head space in my reactor to a minimum while recovering. I also intend to build the helix inside like fab described above and the 6" flue in the heater already has a very nice heat reflector thingy in it... I got it off of kijiji for free complete with a nice clean Becket burner...
Jon

Fabricator,

Do you experience any soot build-up in you exhaust pipe due to the relatively cool wall temperature?

The grease burner burns very clean I have it in my pole barn with no exhaust stack, but every couple of months I run a small chimney brush through it.

Based on 30+ years working with boilers in heating applications, it is a VERY bad idea to run anything but chemically treated WATER thorough a boiler. The temperatures at the heat exchange surfaces inside the boiler will exceed the limits of any propylene or ethylene glycol antifreeze. The antifreeze will break down, become acidic and cause corrosion in the boiler and throughout the system. Running veg oil through a boiler would be even worse. The VO will 'burn' and break down inside the boiler, fouling the boiler surfaces and significantly reducing the heat exchange within the boiler. The boiler will be irreparable crap within a few days of operation with veg oil.

If you want to do this successfully use a FPHE to heat the VO and run ,treated water through the boiler. A typical 15 to 20 plate FPHE used in VO conversion applications will transfer about 80k to 100k BTU, which should be about the size of most residential heating boiler outputs. Determine the BTU rating of the boiler from the nameplate and size the FPHE accordingly to assume approximately 90% heat transfer across the FPHE. If the nameplate BTU rating isn't available a good estimate can be made from the burner nozzle size. A 0.5 GPH nozzle will produce about 50k BTU, the relationship between GPH and BTU is reasonably liner for most residential boilers.

An oil fired DHW heater won't have the same problems as a boiler because it's a different design.

Fabricator,

Thanks.......................Steve

Not if the heat exchanger is built right, mine has a 6" tube with 1/8 inch wall on the inside, the flame is in this tube, the outer tube is 12" tube with 1/8" wall, in between the two tubes there is a helicle ramp the goes from the bottom to the top that forces the oil to travel round and round the inner tube about 20 times to the top where it exits, inside the flame tube there are half discs that cause the flame to travel a zig-zag up the tube, most of my heat is transfered into my oil.[/QUOTE]

I wasn't talking about the heat exchanger, I was refering to Glycol which will decrease efficiency if it is run through the boiler itself. And might I add with my "30 yrs plus experience" running glycol through a boiler is not all that uncommon. Example: when heating natural gas before it is sent through the meter runs it is first sent through a boiler filled with propylene glycol. The reason for heating the gas is after it is measured in the meter runs, it then goes through the regulators this rapid release brings the gas temprature way down, during a high demand peak period the regulators could easily freeze up and stay stuck in there position.(no more regulation!)

Example 2: when converting LNG back to a gas form, the LNG is run through a Propylene glycol bath boiler and then sent out for distribution to homes and bus.. This concept has been used for decades!


But getting back to the original thread the man is trying to use a conventional house boiler to heat his oil I'm just trying to help I have been doing this kind of work in the industrial environment all my life, this is my bread and butter, I will not be offended if someone does not want to use my advice. Be safe ......happy brewing!

[QUOTE]Originally posted by Jon Heron:
the heater already has a very nice heat reflector thingy in it...



Jon you make me laugh!!

[QUOTE]Originally posted by john galt:
Running veg oil through a boiler would be even worse. The VO will 'burn' and break down inside the boiler, fouling the boiler surfaces and significantly reducing the heat exchange within the boiler. The boiler will be irreparable crap within a few days of operation with veg oil.

Another good point thanks John!

The reason I am considering a boiler/heat exchanger is because I am tired of changing chromalox heater elements. They foul with vwo crust and die infrequently when I dewater. The new processor has a capacity of 220 gallon I am contemplating a household water heater as a electric powered boiler. how will antifreeze (dexcool used by manufacturers for newer vehicles with aluminum components to reduce electrolysis or corrosion) affect a this type boiler and how many watts (in heating elements) and what capacity will I need. Heating oil to 194 for dewatering

Marvin,
For the size of batch's you are talking about I would consider nothing less then a bio or veg powered heater, forget the electric heat!
Instead of an electric water heater go for an oil fired water heater and fuel it with bio, they are plentiful in the classifieds for free if you can pick it up. All the modifications I am doing to mine are likely not even necessary... I can just never do things the easy way!
Jon

A water heater either electric, gas or oil will take forever to heat 220 gallons of oil, just trying to make it circulate semi evenly would be quite a feat.