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ASME PTC 3.2-1990 scan — Test Code for Solid Fuels
📐 ASME PTC 3.2-1990 is the ASME Performance Test Code on solid fuels (Solid Fuels), prepared by PTC Committee No. 3 on Fuels. Together with PTC 3.1 (Diesel and Burner Fuels — liquid fuels) and PTC 3.3 (Gaseous Fuels), it completes the ASME fuel test-code trilogy. Solid fuels primarily means coal — anthracite, bituminous, sub-bituminous, and lignite — together with its combustion-derived forms, historically also coke and wood; the code spans the full chain from sampling and sample preparation through proximate analysis, ultimate analysis, calorific value, ash characteristics, and grindability. It is the basis for fuel acceptance, operating adjustment, and input-heat accounting in boiler performance tests (e.g., PTC 4). This document is a scanned copy with no text layer; the material below is compiled from the standard’s title and subject area together with generally accepted coal-analysis practice (ASTM methods and comparable industry practice).
⚠️ This article is an informational overview of ASME PTC 3.2-1990 prepared from a textless scan; specific clauses, formulae, and tolerances must be verified against the purchased official text before engineering application.
1. Object and Scope 📌
Consistent with the PTC 3 fuel family, the purpose of this code is to specify standard methods for determining the physical and chemical properties of solid fuels, providing a unified basis for heat-input accounting in boiler performance tests and for fuel trade acceptance. Principal scope and points:
- Object: solid fuels used in combustion and gasification equipment, primarily coal across the rank range (anthracite, bituminous, lignite) and size range (run-of-mine, commercial coal, pulverized coal).
- Content: sampling and sample preparation; proximate analysis (moisture, ash, volatile matter, fixed carbon); ultimate analysis (carbon, hydrogen, nitrogen, sulfur, oxygen); calorific value; ash fusion characteristics; grindability and ash composition.
- Bases of reporting: clear definitions and conversions among as-received, air-dried, dry, and dry ash-free bases so results are comparable.
- Referenced methods: extensive adoption of ASTM coal test methods (e.g., D2013 preparation, D3173 moisture, D3174 ash, D3175 volatile matter, D5865 calorific value), forming the complete sampling-analysis-calculation-reporting chain.
💡 In boiler performance tests (PTC 4), input heat = fuel flow × as-received lower heating value; any error in heating value or moisture measurement propagates proportionally into boiler efficiency and heat-rate calculations — precisely why a solid-fuels test code exists.
2. Sampling and Sample Preparation 🔧
| Stage | Key points |
|---|---|
| Manual sampling | Take increments at prescribed, equally spaced points across conveyor belts, falling streams, or rail cars, covering the full bed depth |
| Mechanical sampling | Automatic samplers cut full-stream cross sections at time- or weight-based intervals to reduce human bias |
| Sample reduction | Cone-and-quartering, riffle dividers, or slotted splitters: reduce stepwise to the required analysis-sample mass |
| Crushing and grinding | Stage-crush to prescribed tops sizes (e.g., 4.75 mm, 2.36 mm, down to 0.25 mm analysis sample) avoiding size segregation |
| Moisture protection | Keep total-moisture samples sealed and airtight; avoid overheating during preparation that would drive off moisture |
🚨 Once a total-moisture sample is opened or overheated during grinding, moisture is lost immediately and the as-received heating value and ash are all corrupted. Total-moisture determination must be performed synchronously with sampling or the sample sealed for transport — the most common and most damaging error in coal testing.
3. Coal Analysis and Principal Indicators 📏
| Determination | Method essentials | Engineering significance |
|---|---|---|
| Proximate analysis | Moisture (D3173), ash (D3174), volatile matter (D3175); fixed carbon by difference | Basic combustion-characteristic data; dictates furnace design and operating parameters |
| Ultimate analysis | Carbon, hydrogen by combustion; nitrogen by Kjeldahl/chemiluminescence; sulfur by Eschka or high-temperature combustion; oxygen by difference | Inputs to theoretical air, flue-gas quantity, and loss calculations |
| Calorific value | Oxygen-bomb calorimeter for higher heating value (D5865); conversion to lower heating value via hydrogen content | Input heat for boiler efficiency and heat-rate accounting |
| Ash fusion characteristics | Deformation, softening, hemispherical, and flow temperatures | Slagging and fouling tendency assessment |
| Ash composition | SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, alkali metal oxides | Slagging and fouling index computation |
| Grindability | Hardgrove Grindability Index (HGI) | Mill capacity and pulverizing energy |
| Sulfur content | Total and combustible sulfur determination | SOx emissions, corrosion, and flue-gas desulfurization design |
💡 Two quick “entries” for judging coal quality: first, ash and volatile matter from proximate analysis — high ash means lower heating value and greater wear; very high volatile matter raises spontaneous-combustion and puffing risk. Second, ash fusion temperature — coals with a softening temperature below about 1200 °C (2190 °F) slag badly in dry-bottom furnaces; check this closely in coal selection and blending.
4. Application in Boiler Performance Testing 🛠️
- Heat-input accounting: during the boiler test, sample continuously or periodically, determine as-received lower heating value, and combine with the coal mass from scales/flowmeters to obtain input heat.
- Basis unification: correct heating value strictly to the as-received basis of actual plant conditions; mixing air-dried and as-received bases inflates or deflates efficiency.
- Blending: for multi-coal blends, sample by weighted average or layer sampling so the laboratory analysis represents the actual furnace feed.
- Reporting system: the report presents analysis results on each basis, conversion relationships, and test conditions for comparison with contract values and historical data.
5. Frequently Asked Questions ❓
❓ Q: What is the difference between as-received and dry-basis heating value?
A: The as-received basis includes total moisture — the actual burning state at the plant; the dry basis removes all moisture for coal-to-coal comparison; the dry-ash-free basis further removes ash to reflect rank. Conversions require moisture and ash data.
A: The as-received basis includes total moisture — the actual burning state at the plant; the dry basis removes all moisture for coal-to-coal comparison; the dry-ash-free basis further removes ash to reflect rank. Conversions require moisture and ash data.
❓ Q: What problems does a low ash fusion temperature cause?
A: With a low fusion (especially softening) temperature, ash particles melt and agglomerate in the high-temperature furnace, reducing heat transfer, increasing cleaning burden, and even blocking flues — a key input to boiler selection and operating adjustment.
A: With a low fusion (especially softening) temperature, ash particles melt and agglomerate in the high-temperature furnace, reducing heat transfer, increasing cleaning burden, and even blocking flues — a key input to boiler selection and operating adjustment.
❓ Q: Why must nitrogen and oxygen also be measured?
A: Carbon, hydrogen, and sulfur determine combustion-product quantities and losses directly; nitrogen affects NOx formation; oxygen is obtained by difference (100% minus the other elements) and is needed for a complete mass balance.
A: Carbon, hydrogen, and sulfur determine combustion-product quantities and losses directly; nitrogen affects NOx formation; oxygen is obtained by difference (100% minus the other elements) and is needed for a complete mass balance.
🔍 Q: How does PTC 3.2 relate to ASTM coal standards?
A: Like PTC 3.1 and 3.3, PTC 3.2 adopts ASTM coal test methods as measurement tools and organizes them into a complete solid-fuels test code; the two bodies reference and stay consistent with each other.
A: Like PTC 3.1 and 3.3, PTC 3.2 adopts ASTM coal test methods as measurement tools and organizes them into a complete solid-fuels test code; the two bodies reference and stay consistent with each other.
