Running a 25 MT White Coal Trial: A Step-by-Step Checklist for Plant Managers

A trial is the most reliable way to learn how white coal behaves in your own boiler, thermic fluid heater or furnace. Datasheets and supplier claims only go so far. A well-planned 25 MT trial gives you your own consumption, ash and operating numbers, so the decision to scale up or stop rests on evidence from your plant. This checklist walks through the work in the order it happens.

Why 25 MT Is a Sensible Trial Size

At Bharat Bio Industries, 25 MT is our minimum order and also our trial minimum. For a mid-sized boiler this is usually enough fuel to run for several days of steady operation, which is long enough to see real behaviour in the feeder, on the grate and in the ash pit. It is small enough that a poor result costs little. The aim is to measure, not to prove a point in either direction.

Step 1: Record Your Baseline Before the Trial

The most common reason a trial proves nothing is that nobody recorded how the current fuel performed. Before the first briquette arrives, collect at least one to two weeks of data on your present fuel.

• Fuel consumed per shift and per day, from weighbridge slips or stock counts.
• Steam generated or heat output delivered, from your flow meter, or hot oil duty for a thermic fluid heater.
• Ash removed per shift, and how often you clean the grate and flue passes.
• Stack temperature and, if you have an analyser, oxygen level.
• Operator notes: how often the feeder is adjusted, how the fire looks, any trips or manual interventions.

Also note the lab values of your current fuel, including its calorific value, because you will need them for the cost comparison later. If you are unsure how to turn these readings into an efficiency figure, our guide on how to calculate boiler efficiency explains the method.

Step 2: Check the Feeder and Grate

White coal is a 90mm briquette, a different size and shape from the coal or small pellets many feeders were built for. Before the trial, ask your boiler engineer to check the following.

• Hopper opening and screw or chain feeder clearance for a 90mm piece, so that briquettes do not jam at the throat.
• Feeder speed range, so you can match feed rate to load without running at the limit.
• Grate condition, air distribution and clinker-removal access.
• Condition of ash handling, because the ash quantity and character will change.

Plants that have converted units before will find our article on converting an FBC boiler to biomass a useful reference for the wider engineering questions.

Step 3: Plan the Lot, Sizing and Storage

Work out how many days 25 MT will last at your normal load. Divide 25,000 kg by your daily fuel use at equivalent heat, remembering that briquettes and your current fuel have different calorific values. Leave a margin, so the trial does not end early because a few shifts ran at higher load.

Briquettes absorb moisture, so decide the storage spot before delivery. Use a covered, dry, raised floor with good ventilation, away from rain and ground damp. Keep the lot in one place so that you can trace every shift back to one delivery. Our storage and handling guide covers the practical detail. Also arrange a way to weigh what is fed into the hopper, since that is the single most important number in the trial.

Step 4: Receive and Sample the Delivery

Treat the delivery as the first test. Our specification is a GCV of 3800 to 4200 Kcal/kg, moisture below 10 percent, ash below 10 percent (typically 2 to 8 percent depending on feedstock) and sulphur below 0.1 percent. These are BBI's own specification, confirmed by the batch lab report, which is available on request. Ask for the report for your batch before the truck is dispatched.

1. Weigh the vehicle in and out and record the net quantity.
2. Look at the load: broken pieces, loose dust, wet patches or foreign material.
3. Take samples from several points in the load, not just the top, and seal and label them.
4. Keep one sealed sample for your records and, if you wish, send one to an independent laboratory of your choice.
5. Compare the lab result with the batch report and note any difference.

Our guide on choosing a white coal supplier lists other questions worth settling before you order.

Step 5: Run the Trial

Duration and Load Matching

Run for long enough to cover your normal range of load, ideally several days and more than one shift pattern. Operate at the same steam demand or heat duty as your baseline period, so that the comparison is like for like. If the load changes for production reasons, record it rather than ignore it. Start with a short settling period for the operators to find the right feed rate and air setting, and mark it clearly in the log so that settling data does not distort the result.

What to Log Each Shift

Common Issues and What They Usually Mean

Feed Bridging

If briquettes arch above the feeder throat and stop flowing, the cause is usually a hopper or throat geometry that suits a different fuel, or fines and broken pieces mixed in with the whole briquettes. Check hopper angle, screen out dust, and avoid overfilling. Agitation or a small mechanical change often solves it. Record the number of events, because frequent bridging is a real cost.

Clinker

Clinker is fused ash on the grate. It points to local overheating, uneven air distribution or an ash that fuses at your operating temperature. Note where it forms, how hard it is, and the load at the time. Adjusting air and feed rate may help, but persistent clinker in a particular spot is a finding to share with your boiler engineer and with us. We do not want to hide it, since it tells both sides what to fix.

Moisture Pickup

If the fire becomes sluggish, smoke rises or briquettes crumble, check the fuel first. Material left uncovered, stored on damp ground or stacked against a wet wall takes up water. Compare a fresh sample from the stack with your sealed delivery sample. If moisture differs, the issue is storage rather than the fuel as supplied.

Step 6: Calculate Cost per Million Kcal and Compare Honestly

The price per kilogram does not tell you which fuel is cheaper. Use this method for both fuels.

1. Divide 1,000,000 by the lab GCV in Kcal/kg to get the kilograms needed per million Kcal of heat input.
2. Divide by your measured boiler efficiency on that fuel, so you count only useful heat.
3. Multiply by the delivered price per kilogram, including freight.
4. Add handling costs, such as labour for ash removal and ash disposal.

Use your own measured figures, not the ones from a brochure, and the same load period for both fuels. Do not forget the real differences. A higher-grade coal can carry more heat per kilogram, so on fuel price alone it may look cheaper, while white coal is not a one-to-one replacement for every coal. Ash handling, cleaning time and any compliance or customer requirements belong in the comparison, and so does the cost of any feeder modification. You can test your numbers on our fuel cost calculator, and our white coal price guide explains how price drivers work.

Step 7: Decide to Scale Up or Stop

Set your decision rules before the trial starts, so the result is not argued afterwards. A sensible set of questions follows.

• Did the delivered fuel match the batch lab report?
• Did the boiler or heater hold its required load without extra operator effort?
• Is the cost per million useful Kcal, including handling, acceptable against your baseline?
• Were any problems traced to causes you can fix, such as storage or feeder settings?
• Does the supplier respond quickly and openly when something goes wrong?

If most answers are yes, scale up in stages, for example to a standard monthly contract, and keep logging for the first few months. If the answers are mixed, fix the cause and run a second short trial. If the numbers do not work, stop. A clear negative result is still a useful outcome, since it saves you from a larger commitment.

Next Step

Our team can share the batch lab report, discuss your feeder and storage setup, and plan the 25 MT lot with you. See the specification on our biomass briquettes page.

Contact our team with your boiler or heater details and location to plan your 25 MT trial.