The garbage furnace illustrated by Hiscox feeds refuse onto a curved parting hearth. Heat from the grate fires dries the material before it slides down toward the grates. The section below shows that historical arrangement. A separate flow calculator compares nominal gas hold-up volume and the split of an entered air supply between the two grate sides.
Garbage Furnace Interactive Calculator
Enter gas flow at chamber conditions, a nominal residence time, total undergrate air flow and the share sent left. These quantities support a volume and flow comparison; they do not establish furnace dimensions, emissions performance or operating settings.
Equation Used
Gas flow is actual volume per second at the chamber temperature and pressure. Air flows share one stated inlet basis. Gas flow and air flow are independent inputs: combustion products and heating prevent treating them as interchangeable. Residence time is an entered comparison value, not a required minimum.
Drying before the grate
Hiscox’s figure 1259e shows plan and sectional views of a furnace with top feed openings, a curved central hearth, fixed grate bars and a main flue. Refuse reaches the raised hearth first, divides toward its sides and then moves down onto the grates. The accompanying description says heat from the grate fire dries the material and notes the possible use of coal to assist burning.
The drawing distinguishes the feed path from the air and gas paths. Blue markers enter beneath each grate. Orange rings mark gas connections away from the section plane; the main flue runs along the furnace. The original plan includes repeated cells, while this animation shows one representative section. Passage lengths and flow velocities are not specified.
Moving fragments illustrate falling and sliding along the hearth and grates. Their color change is symbolic, not a moisture, burnout or residue calculation. The surrounding masonry and the hearth stay fixed. This historical arrangement is not a depiction of a modern two-stage packaged incinerator.
Reading a historical furnace layout
The illustration explains how a drying surface can separate fresh, damp material from the active grate area. Its plan also shows how multiple sections can share a flue. It is useful for understanding the arrangement of early refuse furnaces, without treating the drawing as a current construction specification.
Modern waste-treatment equipment must be considered for its actual feed, combustion system, gas treatment, residue handling and permitted operation. Neither a historical label nor an animated flame demonstrates suitability for a waste stream.
Nominal gas volume and an air split
For a stated actual volumetric gas flow Qgas in m³/s and a chosen nominal time t in seconds, V = Qgast gives volume in m³. This is the rearrangement of nominal residence time t = V/Q. It is an arithmetic comparison, not a chamber design method.
Use gas volume at the relevant temperature and pressure. A flow expressed at standard conditions cannot be inserted as though it were the hot chamber flow. Waste mass rate alone does not determine this value: composition, moisture, combustion air and gas conditions also matter.
The air split is independent. If f is the entered left share divided by 100, Qleft = fQair and Qright = (1 − f)Qair. Both outlets add back to the entered total. These equations allocate a supplied flow; they do not predict what fans, dampers or the grate resistance will deliver.
Nominal residence time does not describe every gas parcel. Mixing, bypassing, temperature history and reaction chemistry affect performance. A volume result supplies no destruction efficiency, outlet concentration or compliance result.
Example: a flow comparison
With actual hot-gas flow 0.70 m³/s and an entered nominal time of 1.0 s, the calculated volume is 0.70 m³. Doubling the time to 2.0 s doubles that volume to 1.40 m³. These are selected comparison values, not recommended operating conditions.
For total undergrate air of 1.0 m³/s and a 50% left share, each side receives an allocated 0.50 m³/s. At a 30% left share, the allocation becomes 0.30 m³/s left and 0.70 m³/s right. The gas-volume result stays unchanged because it uses the separate gas-flow input.
The animation retains the same historical outline throughout. It does not resize a chamber to the volume output, change the waste feed rate or model how an air adjustment affects combustion.
Separate geometry from combustion performance
A drying hearth can be identified from a sectional drawing, but its drying rate cannot. That requires the material’s moisture and properties, its contact with the hearth and the available heat. No drying time or auxiliary-fuel demand is calculated here.
Likewise, the residue is not assumed sterile or harmless, and a visually clear exhaust is not proof of low emissions. Temperature alone does not establish performance. Equipment-specific measurements and applicable approvals govern waste acceptance and operation; this page supplies no startup, repair or fuel-mixing procedure.
Frequently asked questions
What does the curved hearth do?
It divides the incoming refuse and exposes it to heat before it reaches the grates. The animation illustrates that path without calculating drying.
Does this drawing show an afterburner?
No. It follows the historical curved-hearth and grate arrangement in Hiscox figure 1259e. Modern secondary-combustion systems are a different layout.
Why must gas flow be stated at chamber conditions?
Hot gas occupies a different volume from the same amount of gas at standard reference conditions. The volume-time relation needs the actual flow through the space being considered.
Can waste kilograms per hour determine the gas volume?
Not by itself. Waste composition, moisture, added air and gas temperature and pressure are also needed.
Does nominal residence time prove emissions compliance?
No. The calculation contains no reaction chemistry, mixing model, pollutant measurement or equipment approval.
Is the air split a damper setting?
No. It is a chosen division of an entered total flow. Damper angle and delivered flow depend on the fan and the resistance of each path.
Are the animation speeds physical predictions?
No. Falling fragments, flame shapes, air markers and gas rings illustrate the arrangement at a display pace.
Can the result select an incinerator for a site?
No. Equipment selection also needs the waste specification, capacity, combustion and gas-cleaning performance, residue management and applicable approvals.
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