Comparison of hand firing and stoker operation using bitumin

Comparison of hand firing and stoker operation using bituminous coal

Introduction

The purpose of this paper is to relate my experience firing the same house and the same boiler with both a stoker and hand firing using bituminous coal. My main goal was to reduce smoke and that has been a complete success but there are other things to consider.

Background

I built this house and installed a pre WW II American Radiator Co. Red Flash Boiler, model 1-9. I fired it by hand for 4 winters. I have just finished the third season with a new Will-Burt model S 30 stoker. Dan at the Will-Burt Co. helped with the installation drawings. I think Dan and the Will-Burt Co. know what they are talking about and I would recommend that you take their advice and treat it as if it were engraved in stone and handed to you by Moses himself. I designed the house from the beginning to have a coal boiler and the boiler room is well sealed and isolated from the rest of the house. Separate ventilation is provided and there is NO problem with smoke, dust or fumes in the house. My years of experience in the bituminous coal business influenced my decision to use bituminous coal rather than any merits of using anthracite vs bituminous coal. I heat with coal from early October into May. I burn about 12 - 14 tons of coal a year

Coal Analysis

The coal mined in this area is full coking and low volatile. A typical analysis of coal available for home use would be:

% Moisture 3
% Volatile 16 - 18
% Ash 12
% Sulphur 2.5
B.T.U. 12.500
Ash Fusion ~2400
A.S.T.M. Coke #9

Operation


There is discussion in this forum about a stoker being less work and referring to a stoker as a "girly fireman" I don't find that to be true. You still have to shovel the same amount of coal and you still have the same amount of ashes to deal with. I find it takes about 10 minutes more each day to conduct the "Hunt for the Red Hot Clinker" as opposed to giving the shaker grate a few strokes. The main difference I've found is that you can work on your schedule rather than on the schedule of the weather or the boiler. A few hours one way or the other doesn't faze the stoker where as the house will get cold or the fire will go out or it will smoke like crazy if you are late or early with hand firing. With the stoker, depending on your skill and coal, the tuyeres will plug up sooner or later and you are stuck with a firebox full of red hot stinking, smoldering coal. You can either let it cool down naturally (which may take 24 hours or more) or you can take it out hot but either way you must take everything out of the firebox and clean each and every tuyer perfectly clean. This involves a trouble light, screw driver, mirror and getting in the firebox. I've practiced for 3 years now and it still takes me 1 hour to restart the fire. With hand firing you can rebuild the fire in 10 or 15 minutes. With care and practice hand firing doesn't get you too dirty. It only takes a few shovels of coal and the draft will take most of the dust away from you and up the flue. The stoker will go for several days without you touching coal but then you have to do 20 to 50 repetitions with the shovel and pour the coal into the hopper which is bound to get you dirty. But if you are going to change your clothes and shower anyway it doesn't matter. The stoker operation will produce more fly ash. Plan on cleaning the boiler about once a week. I have found the stoker to hold fire well during warmer weather. This allows me to extend my coal burning season by several weeks in the fall and spring. With only a little work it will save you from using your back up heat for every cool or rainy evening.

Fireman's skill

With good coal, day to day hand firing doesn't require a lot of skill. My grandmother did it and my mother did it when she had to and my wife did it when I worked out of town. (Your wife can do it too if you can figure out how to motivate her.) The stoker requires careful identification and removal of the red hot clinkers and replacing the coke without plugging the tuyeres. Depending on the boiler and the coal, you have to set the draft, air delivery and the overdraft air. It took me a year and a change in coal suppliers to become marginally competent. After 3 years I am still learning and improving my technique.

Coal

By hand firing, with practice and a forced draft and a segregated coal bin so you can always get a shovel or two of good coal, you can burn some real junk. Some of that refuse they should pay you to take away. If you have lots of time and want to save every dollar, this is a good way to do it. With the stoker you are going to have to buy stoker coal. Period. With the stoker you can't use rock or big lumps or fines or mud or wood or trash. My advice is to buy the very best stoker coal you can find. An advantage of stoker coal is that you can move it easily with an inexpensive grain auger.

Smoke

There are several methods for reducing smoke when hand firing. Most have been discussed in this forum. Use a hotter fire, leave an open area of the fuel bed, fire more often with less coal each time, carefully set the overdraft, fire after your neighbor goes to bed and before he gets up etc. These all work to some extent to reduce smoke but none eliminate it. There will still be times when because of your schedule and weather conditions that you will choke the whole neighborhood with smoke. My experience with the stoker is that I have reduced the smoke by at least 95 %. It is very rare that I see or smell even a hint of smoke. A cigarette will absolutely make more smoke than my coal boiler.

Cost

The stoker isn't cheap. A new one is in the $5,000 range plus installation. The coal is more expensive. Depending on circumstances a guess would be $20 - $40 per ton more compared to run of mine coal of the same analysis. Will-Burt Company says that you will burn less coal with the stoker and I am sure that is true but don't plan on educating your children with the savings.

Conclusion

The stoker will absolutely greatly reduce smoke and fumes. Most people will never know you heat with coal. If your neighbor has a problem with your stoker he has a lot more problems than that. You will tend the boiler when you want to rather than when the boiler or the weather dictates. The cost will be higher. Exact dollar costs or percentages will depend on your circumstances and how much coal you burn.

I think a stoker is better especially if the appliance is the primary heat source, however I always recommend having a supplemental appliance that doesn't require electricity to run/heat during outages unless a generator is used. Also, as you mentioned, a stoker allows you to leave home for extended periods without tending whereas a hand fed is limited.
I do have one question. How are you lighting your stoker?

Excellent write-up! Thank You and welcome to the forum.

after having both a hand-fired and a stoker, i can say with certainty that i prefer the stoker, in my situation it is less dirty (my hand-fired setup wasn't that dirty to begin with, but this is cleaner) but most importantly as you've identified, it allows a little "wiggle room" on reloading and ash removal which is very, very, nice.

I think the biggest way to make a stoker even more convenient is, obviously, a decent setup, bin close to the hopper, a method of controlling dust from coal and ash handling (grain auger etc), but, MOST importantly is the coal. I've found after experimenting with four very different coals that ideally for stoker use you would have a coal that is 1. high volitile 30+ 2. Mid to high fixed carbon 3. mid ash fusion 4. consistant and proper size; and THE two most important: LOW swelling index (under 5) and LOW ash (under 8%). Obviously we must make sacrafices for what's regionally available and mandatory things like maximum size, and unfortunately i've had to make compromises, but ideally, the characteristics in coal that i've mentioned above would be what i burn.

Thats a good article for the Knowledge Base.
Time to get rolling
Logging into the Knowledge Base

rockwood wrote:I think a stoker is better especially if the appliance is the primary heat source, however I always recommend having a supplemental appliance that doesn't require electricity to run/heat during outages unless a generator is used. Also, as you mentioned, a stoker allows you to leave home for extended periods without tending whereas a hand fed is limited.
I do have one question. How are you lighting your stoker?

How do I light the stoker?
1. Clean out firebox and tuyeres perfectly clean
2. Turn auger by hand to make sure it is free
3. Ball up 2 sheets of newspaper & place in retort
4. Split big handfull of kindling (about the amount in a 2X6 eight inches long split fine
5. Stand kindling vertically on paper
6. Carefully place 1 shovel of fresh coal on each of four sides of retort
7. Light with propane torch
8. When wood is burning freely close air control so it is only open 1 turn
9. Turn on stoker
10. As fire increases gradually open air control to desired setting

An excellent article, thank you..

Could you add a few photos to help educate the 'anthracite only' folks on the forum?? I'd like to see what you meant by 'replacing the coke'..
I do understand that you have to use clinker tongs/ rake/hoe/small shovel to clean out the ash and clinkers around the tuyers and on the surrounding fire-clay masonry.

Since most of us have anthracite stokers, where the only issue is feeding the fire, the ash just falls off the end or edges of the burner surface, we are not familiar with the way a Bituminous Stoker has to be cleaned daily or frequently..

Since I have two old 'Iron Fireman' Bitum stokers [predessor to the Will Burt].. I have researched their use a lot.. but there is a great lack of good photos showing a completed install and proper opperation..

Thanks again for a very interesting post.

Greg L

I also found the article interesting. I have one question, what are tuyers?

Tuyere are the air fed tubes and perforated burning surface in

a stoker where the combustion takes place.In most of the current

stokers the pot and cast iron burn plates and the air feed tubes

would all be part of the tuyere assembly.In the older units the

air feed tubes were referred to as the tuyere of the furnace.

Technically it is only the tube through which moves the air to

the burn area. The word "Tuyere"is a word for tube.


BigBarney