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My coal stoker boilers much improved performance

leonz Member Posts: 1,122
I have improved my coal stokers performance a great deal by modifying the hopper which us set up to gravity feed rice coal to the stoker.

About my system:

I use a Honeywell L8124L triple aquastat after tossing 2 failed hydrolevel aquastats to the wolves.

I have a Bell & Gossett RB-122-E as a low water cut off control wired in as the first 110 volt electric control for the boiler.

I have a Honeywell L4006 single aquastat to control the dump temperature of the boiler
190 degrees with a ten degree differential.

I have an Intermatic 30 minute timer to act as a the hold fire timer to prevent an outfire-
loss of coal fire.

The Intermatic is set to operate 14 minutes every 30 minutes if there is no heat call.

The Intermatic timer operates in four sequences of 4 minute/3 minute/4 minute/3 minute sequences over thirty minutes when there is no heat coal.

I have my low limit temperature set at 150 degrees Fahrenheit and my high limit temperature set at 170 degrees Fahrenheit with a ten degree differential.

How I reduced my coal use:

The stoker operates slowly with the adjustment set at 12 threads out per cycle-fewer threads out means you will have a faster feed rate.

I have reduced the size of the hoppers opening by 12 square inches by placing 2 pieces of
2 inch by 12 inch by 1/8" thick flat stock over the open ends of the hopper opening.

A lesser amount of rice coal is dropping and feeding into the stoker and the firebed is still
covered with a full width of coal as the rice coal is simply filling in the void under the flat stock by rolling into place and we still have the proper ratio of ash burning coal and unburned coal on the flat grate stoker at all times.

In the process it has slowed the delivery of coal to the coal stoker and lessened the load on the coal stoker motor as there is less coal bearing down on the stokers pusher plate and reducing the strain on the pusher plate, gearbox and stoker motor.

So after 2 heating season years I can definitely say the hopper modification is a safe method to save fuel and a success as I am only burning about 80 pounds of rice coal per 24 hour day.

Some mornings when I change the 4 gallon ash bucket I find that there is only one inch of ash in the bucket.

I will be installing full firebrick on the floor of the boilers base plate after the heating season and I expect to save even more fuel.

I must be doing something right.