The dawn of a cogen system

[Equine]

Hey all!

It's been quite a while since I last posted. I've been quite busy and have successfully acquired a diesel engine!

It's a Hungarian make, and "BL-12" is it's designation. Here are it's main factory specs:

- Single cylinder four stroke horizontal arrangement
- Bore: 120 mm (4.72")
- Stroke: 140 mm (5.51")
- Displacement: 1.58 liters (96.4 cu. inches)
- Compression ratio: 1:16
- RPM: 900 - 1200 (the speed can, of course be set to lower RPMs but the factory defaults are 900, 1050 and 1200 RPM, selected by a lever)
- HP: 9-12
- Torque: 7.15 mkg (at nominal power, which is around 10 HP)
- Fuel consumption: 180-195 g/HPh
- Forced, closed oiling system (no need ot manually oil anything)
- Weight : 350 kg (772 pounds)

It's a low maintenance, heavy duty engine, it was the most powerful of the stationary engines ever manufactured in this country at that time.

Here are some pictures of my engine, in it's current state (quite worn!):





I have taken off the valve cover, and found this:




The oil is heavily contaminated, and there is a lot of dirt all over the place. I'll have to take off the cylinder head, and take the valve assembly apart, to clean it. When I turn the flywheel the exhaust port doesn't only blow but also sucks , randomly, which means that the exhaust valve is probably in need of some proper attention. This notion is further fueled by what the exhaust looked like when I took the muffler off!! Several handfuls of rust mixed with soot, poured out of the muffler and the exhaust port.
This is a look inside the exhaust port after I took the bigger chunks out!



This is the stuff that poured out of the muffler and exhaust port...nasty!


Also the air filter and intake is in rather bad shape:







Bottom line is, I'll have to take the whole thing apart, clean every bit, and put it back together. I'll probably have to replace the cylinder insert and the piston, as they are heavily worn from what I was told. The valves may need to be replaced as well. The decompressor lever doesn't seem to work at the moment. This engine actually RAN in this condition...

So this is where it all starts I'm planning on building my cogen system around this baby! Any thoughts on cleaning and stuff?

[mobile_bob]

whatever you do, don't use caustic soda on the air cleaner element, the steel wool looking stuff is
galvanized (at least it is here in the US, so protect from rust) and the hot dip will eat away the zinc leaving
the element to rust down and get inhaled into the engine later.

a good cleaning solvent would work wonders, however it is hard to get in some area's
failing that perhaps kerosene, or even gasoline "if" and only "if" you are careful to do it outside and away from
ignition sources.

i have used diesel, but for what  you have its a mess.

oven cleaner is really good, it is caustic so keep it out of the aircleaner innards, it does however work very well
to spray on, wrap in black plastic and let the heat of the sun help to loosen it all up.

brake cleaner is pretty good when you get it down to just cleaning off oily stuff, the caked on stuff will need some work

you might consider taking it all apart and take it to an engine shop and have them put it through their hot tank, or dishwasher.

in my opinion, unless they want an arm and a leg, it is probably the best money you can spend just having them do it.

just don't let them have your air cleaner! that is if you plan on reusing it.

bob g

[Equine]

Hey!

Thanks!

I was also told, that citric acid is good for cleaning out the fuel tank, removing rust from it etc. Letting the tank's inside soak in it for a day or two, is said to work very well.

I'm planning on taking the whole thing apart, starting with the cylinder head. From what I can tell the valves don't seal as they should, and the old engine oil is pretty much making everything stick.

As for the air filter, I used some diesel to get rid of some of the dirt, just a quick rinse. You can see that in the lower part of the filter housing there is this gooey thick "mud". I was able to get most of that out by puring diesel in it and stirring it.
About the filter element, I think I'll try to get a new one, as there is a dealer here who sells brand new parts for these old engine (he got his hands on a massive stock way back when). He might have what I need. I'm also thinking of replacing the fuel injector. I took out the screw-in heater torch holder (I hope that's what it's called in English), and it's end is covered in thick soot. I'm guessing the injector is in no better shape (I was unable to unscrew that for now).

And yes, once I took it apart and see what shape it is in, I'll probably take it to an engine shop and have it cleaned professionally. Eventually I want to remove all the old paint and rust from the exterior surfaces as-well, and re-paint.

[vdubnut62]

Wow, that has real potential for a very looking nice nice looking co-gen setup.
Ron

[Equine]

Hehe thanks! I'm hoping for something like that!

[Tom Reed]

Since it's hopper cooled, you are going to need to make a top plate of some sort for the reservoir so you can have a closed loop system.

[Equine]

Yes, that's the plan, also I'm planning on utilizing the exhaust heat of course. I do wonder how heat dissipation is balanced between the cooling water, and exhaust. I imagine most of the heat is disposed via the exhaust gases.

[mobile_bob]

engines of this design break down approx this way

~32% mechanical power
~33-34% to the cooling system
~28% going out the exhaust
the balance being dissipated via radiation, noise and vibrations

generally the cooling system takes most of the heat from the burning of the fuel

the above from an engineering text, and is supported in testing of a 195idi changfa
wherein i am able to measure those waste heats and determine that indeed the coolant captures
more of the heat than what goes out the exhaust.

this is probably more so the case if the engine is running cooler than it should because of an oversized cooling system
or part or low load operation.

i am guessing that the DI versions might be a bit closer in the spread, and maybe about equal if the DI version is running up
to full load and full operation temperatures.  larger bore engines ought to be about equal split between coolant and exhaust, and
the amount of heat being converted to mechanical power probably works out to be a point or maybe two points higher as well.

in any event for practical applications,  i would think that if the engine is running up to full operating temperature and full load
the heat balance is about equally split between the coolant and exhaust.

bob g

[vdubnut62]

If only we could get the Shrink Ray working, we could mail these things in a flat rate box.   (RE: Despicable Me , yes I have Grandkids.)
Ron.

[Equine]

Thanks!

Getting the heat out of the hopper reservoir seems simpler than catching what's coming out of the exhaust. Once the engine is rebuilt and working properly, I'll probably put a sealed lid on the hopper (as it was suggested here before) ,and circulate water through it. It would be filled with distilled water, and would go to a heat exchanger in a larger (300 liters or so) tank. This way the engine cooling would be a closed loop system. Though the water would eventually dissolve iron, copper, etc, and would deposit that in the piping anyway. But generally a cooling system heat extraction is quite straight forward.

As for the exhaust I find it a lot more challenging. I read some posts on this forum which dealt with exhaust heat exchangers and I saw that the most common problem is soot deposition. Engines running on SVO or WVO, or other heavier fuels, tend to clog these exchangers relatively fast. Also the efficiency is a major question. The exchanger can be as simple as a double walled pipe, or it could be a more complicated and relatively expensive shell and tube type. It shouldn't choke the engine but it needs to have a high enough surface area to effectively extract heat from the exhaust while avoiding overly rapid clogging.

A bit of a dilemma I'm having with this large water hopper this engine has is, that it has a relatively large surface area, which will dissipate quite a lot of heat I think. Hence I'm considering that during the rebuild I would insulate the hopper, on the outside. Maybe that would give me a bit higher extraction efficiency.

My only problem with a shrink ray , if it would exist, is, that though the engine would fit in my palm, it would still weigh 350 kg )) .One hell of a toy!

These BL-12s are relatively rare. Funny little story actually...The company that manufactured these here in Hungary, actually copied most of the design elements from a German engine, the Cunewalde 1H65. They didn't like that and forced the Hungarian company to stop manufacturing these engines. So the BL-12 and its smaller brother the BL-7 are not very common, they are hard to find (especially the BL-12). I was very happy to find this one! The engine it self cost me $ 300 (the previous owner got it for $ 500, in pretty much the same condition, he never used it!), plus the cost of hauling it 260 kilometers (I payed about a hundred bucks for the fuel).

[vdubnut62]

That's a super find. Can you just remove the hopper and replace it with a plate?
Ron

[Equine]

Problem is that the hopper is part of the "mono-block" that makes up the body of the engine, it's a single casting. And I don't really want to "hack" it off, so it will probably stay on.

[vdubnut62]

Huh! I didn't realize that it was one big casting, I assumed that it was bolted together like the changfa types.
That could be a challenge to move around. Best of luck, the engine really looks like it has a lot of potential for a long runner.
Ron

[Equine]

Here's a pic that shows the casting more clearly:


And yes, I hope that after the overhaul this engine will serve it's purpose quite well.

Oh and, after looking into some data on this engine, I realized that the flywheels on it are a tad small. It has the same flywheel size and mass as it's smaller brother, the BL-7, which delivers 7 HP at 1200 RPM, while this one delivers 12 HP at the same rev. The "RPM irregularity" (there might be a different English word or expression for this) is around 1/65 (note: it's 1/107 for the BL-7) , and the recommended value for an AC generator is 1/300. So I'm thinking of somehow incorporating a larger flywheel into the system, later on. Not directly on the engine shaft, but probably belt driven by it, and on the same shaft as the generator. That should reduce the "jitter".

Edit:

Just re-checked the flywheel mass is not the same for the two types. It's 42 kg for the BL-7 and 49 kg for the BL-12, per flywheel. Not a big difference, but probably most of the mass difference is on the rim of the flywheel, where it makes more of a difference. Still, I think a large, say 100 kg, additional rotating mass (preferably a spoked flywheel, where most of the mass is on the perimeter), would be greatly beneficial.

[wiebe]

Looks like the head is bin very hot ,ore run on very old oil.
In the pics of yhe flywheel is there a crack in the flywheel ore is it dirt?