Quick answer: A linear burner is chosen by matching three numbers to the process — the required heat input (kW), the working width over which that heat must be distributed, and the available combustion space. The E-Type linear series from E10 to E60 covers these cases by scaling profile length rather than flame intensity, which is why a wider line is not simply a bigger burner. Select on heat flux per metre of profile, confirm the fuel and air supply can meet it, then verify the control cabinet can hold the turndown ratio the process actually cycles through.
What makes a linear burner different
A conventional round burner releases heat from a single nozzle into a roughly circular pattern. That is efficient when the load is a tank, a small chamber or a pot. It is a poor fit when the load is a wide, flat or continuously moving surface — a drying tunnel, a curing oven, a paint line, a textile stenter, or a conveyor carrying parts through a heat zone.
Heating a wide strip with a single round flame produces a characteristic defect pattern: a hot band down the centre, falling off toward both edges. Operators compensate by slowing the line, which wastes capacity, or by raising the set point, which overheats the centre and can scorch or distort the product.
A linear burner solves this by distributing combustion along a long, narrow profile. Instead of one flame, the burner presents a controlled line of heat. Three engineering consequences follow:
- Uniformity across the width. Because the heat source is geometrically similar to the load, transverse temperature variation drops sharply compared with a single-point flame.
- Scalable width. Capacity is added by lengthening the combustion profile, so a wide process is served by a long burner rather than by several round burners with overlapping zones.
- Shallow installation depth. A linear profile needs less chamber depth than a round flame of equivalent output, which matters when retrofitting into an existing oven.
These properties make linear burners the default choice for continuous-process heating where the product moves through the heat zone and dwell time is fixed by line speed rather than by burner output.
Reading the E-Type range: what E10 to E60 actually changes
Model numbers in a linear burner series can be misleading. A common assumption is that a larger number means a hotter or more powerful flame. In practice, an E-Type series scales mainly along the length of the combustion profile, which changes where and how widely the heat is applied — not how aggressively it burns.
Understanding this distinction prevents a costly mistake: specifying a longer burner to solve what is actually an insufficient-heat-input problem, or specifying a shorter burner for a wide line and then trying to compensate by increasing gas pressure, which raises flame temperature at the cost of uniformity and emissions.
The three variables that scale together
When moving up an E-Type series, three parameters generally move together and must be quoted as a set:
| Parameter | What it controls | Why it must be quoted with the others |
|---|---|---|
| Profile length | The width over which heat is distributed | Determines whether the burner can span the load without gaps |
| Nominal heat input | Total kW delivered at rated firing | Sets the achievable line speed for a given product mass |
| Air and gas connection size | The flow the valve train and pipework must supply | A longer profile needs more total flow; undersized pipework caps output below nameplate |
The practical implication is that burner selection and the surrounding installation cannot be specified independently. A quotation that names only the model number, without the corresponding connection sizes and required supply pressures, is incomplete.
Heat flux per metre is the number that matters
Two burners with the same total kW can behave completely differently depending on how that output is spread. The governing quantity is heat flux per unit length — thermal power divided by the effective profile length — usually expressed in kW per metre.
Heat flux per metre determines:
- Peak surface temperature at the burner face, which constrains material selection and service life.
- Whether the product can absorb the heat without damage — a high flux on a thin or heat-sensitive web will scorch or warp it even if total energy is correct.
- NOx formation, because higher local flame temperature increases thermal NOx. This matters in jurisdictions with emission limits.
- Recirculation behaviour in the chamber, which affects temperature uniformity along the length as well as across the width.
A useful discipline when comparing proposals: ask each supplier for the heat flux per metre at the intended firing rate, not just the total kW. Two offers that look identical on a summary sheet can differ by a factor of two in local intensity, and that difference shows up as product quality variation and maintenance interval — not as a number on the datasheet.
Turndown ratio and the real operating point
Burners are rated at maximum firing, but most processes spend the majority of their time well below it — warming up, holding temperature, idling between batches. The turndown ratio is the ratio between maximum and minimum stable firing rate, and it determines whether the burner can actually modulate to match demand.
If the turndown ratio is 5:1, a burner rated at 500 kW can modulate down to roughly 100 kW while staying stable. Below that point it may cycle on and off, which produces temperature oscillation and shortens component life. A process that idles at 15% of peak needs a burner whose minimum stable firing rate is below that, or a control strategy that accepts cycling.
When reviewing a specification, the question is not "what is the maximum output" but "over what output range does the burner remain stable, and at what excess air". Those two numbers together define the useful operating window.
Matching the burner to the furnace geometry
Installation geometry constrains the selection as much as the thermal duty does. Four measurements should be taken before requesting a quotation:
| Measurement | What it decides | Common error |
|---|---|---|
| Working width of the load | Minimum profile length needed to span it | Measuring the chamber width instead of the product width, oversizing the burner |
| Available mounting depth | Whether a linear profile fits or a round burner must be used | Assuming a shallow oven cannot take a linear burner without checking the profile cross-section |
| Distance from burner face to product | Chamber volume and air entrainment upstream of the load | Placing the burner too close, causing streaking rather than uniform heating |
| Duct or exhaust arrangement | How combustion products leave and whether recirculation is needed | Ignoring extraction, leading to pressure imbalance and flame disturbance |
Air supply is the most frequently underestimated item. A linear burner consumes combustion air in proportion to its firing rate, plus excess air for combustion quality. If the burner is fed from the same plant air as other equipment, pressure drops when other loads demand air, and the burner either loses output or runs rich — producing carbon monoxide and soot rather than the clean flame the datasheet describes.
Combustion air as a design input, not an afterthought
Two arrangements are common: forced draft, where a fan supplies combustion air at controlled pressure, and induced draft, where the exhaust pulls air through the system. Forced draft gives more predictable control across a range of chamber pressures and is generally preferred where the process cycles. Induced draft suits simpler installations with stable demand.
Whichever is used, the air supply must be sized for the burner's maximum firing rate with margin — not for the average operating point. This is a design decision, not a burner detail, and it is where many installations lose the performance the burner was selected for.
Specification comparison
The table below summarises what changes across a linear burner range and what does not. Figures are indicative of the category; actual values must be taken from the supplier's datasheet for the specific model.
| Attribute | Shorter profile (e.g. E10–E30 class) | Longer profile (e.g. E40–E60 class) |
|---|---|---|
| Typical application | Narrow ovens, small drying sections, edge curing | Wide tunnels, full-width curing, large drying lines |
| Transverse uniformity | Good over the covered width | Good across a wider span, but needs correct chamber geometry to avoid edge losses |
| Air and gas flow demand | Lower total flow; smaller pipework | Higher total flow; larger valve train and headers |
| Mounting depth | Shallow | Shallow, but requires more room along the line |
| Fuel-range flexibility | Available across standard fuels | Available, but waste-oil and methanol variants need specific nozzle and material configuration |
| Control requirements | Simple modulating control often sufficient | Multi-zone control or profiling is often needed to hold uniformity along the length |
Note the last row. On a long profile, uniformity across the width is inherent to the design, but uniformity along the length is not guaranteed. As combustion products travel down the chamber, they cool and change composition, so the far end can run cooler than the near end. Where the process demands a flat profile along its length, the burner is divided into independently controlled zones, each with its own modulation.
Selection checklist before you request a quotation
Providing these items with an enquiry shortens the quotation cycle and reduces the risk of a mismatched supply:
- Process type and product — what is being heated, and whether it is stationary, indexing or continuous.
- Required heat input — calculated from mass flow, specific heat and temperature rise, including warm-up demand.
- Working width and chamber dimensions — product width, chamber width, mounting depth, burner-to-product distance.
- Target temperature and uniformity tolerance — the acceptable variation across the product, in °C.
- Fuel type and supply conditions — gas, LPG, diesel, methanol or waste oil, plus supply pressure and calorific value.
- Operating profile — peak duty, holding duty and idle duty, so turndown can be checked.
- Emission limits — applicable NOx and CO limits in the destination market.
- Control expectation — manual, modulating, PLC with remote monitoring, or integration with an existing plant system.
Items 2 and 6 are the ones most often omitted, and they are the ones that determine whether the delivered burner can actually cover the process. A burner sized on peak duty alone will short-cycle for most of its life; one sized on average duty will never reach temperature on a cold start.
What to verify on delivery
Confirm the delivered configuration against the order before installation: fuel type, profile length, connection sizes, control cabinet specification, and the presence of the documentation set — wiring diagram, commissioning procedure, and a spare parts list indexed by the configuration supplied. Burners are frequently modified during manufacture to suit a specific fuel or emission requirement, so the nameplate rating alone does not describe what was shipped.
Frequently asked questions
Can a linear burner replace several round burners on an existing line?
Often yes, and it usually improves uniformity, because the heat source then matches the load geometry. The constraint is physical space: a linear profile needs an unobstructed run along the line. Where the existing chamber is divided by supports or baffles, the profile length available may be shorter than the load width, in which case multiple shorter linear burners in separately controlled zones can achieve the same result.
Does a longer burner always mean better uniformity?
No. Uniformity across the width improves with profile length, but uniformity along the length depends on chamber airflow and on whether the profile is zoned. A long single-zone burner in a poorly designed chamber can show a cooler far end. Where along-length uniformity matters, zoning the control is more effective than simply lengthening the burner.
What turndown ratio should I specify?
Start from the process, not the burner. Determine the lowest stable duty the process genuinely needs — typically the holding load, not the warm-up load — and divide the maximum firing rate by it. Specify a turndown ratio at least that wide, and confirm at what excess air the lower end remains stable.
Can one burner run on more than one fuel?
Dual-fuel and multi-fuel configurations exist and are common where supply security or price volatility is a concern. They require a valve train and nozzle arrangement that supports each fuel, and the changeover logic must be defined. Performance on the secondary fuel is usually not identical to the primary, so both operating points should be specified and tested.
How is a linear burner sized for a drying tunnel with variable line speed?
Size for the maximum line speed at the minimum product loading, which is the point of highest heat demand per unit time. Then check that at low line speed the burner can turn down far enough to avoid overheating. Variable line speed and wide turndown demand often mean multi-zone control is the practical answer rather than a single oversized burner.
Need help selecting a linear burner for your process? Send us the process type, required heat input, working width and fuel available, and our engineering team will propose a configuration with the corresponding connection sizes, control arrangement and emission data for your market.
