Get Instant Quote ->
Chain Grate · Solid-Fuel Fired · Closed-Loop Thermal Oil

Coal/Biomass Fired Thermal Oil Boiler for Low-Fuel-Cost High-Temperature Heat

EPCB coal/biomass fired thermal oil boilers deliver 700–14,000 kW (60–1,200 ×10⁴ kcal/h) of high-temperature process heat at up to 320°C, with 76–85% rated thermal efficiency by capacity. Also called a thermal oil heater, hot oil heater, or thermic fluid heater, this product burns solid fuel — soft coal, biomass, wood chips, pellets, or rice husk — on a chain grate to heat thermal oil in a closed loop, reaching 320°C at only 1.1 MPa. Buyers choose solid fuel for lower fuel cost, accepting more site infrastructure and lower efficiency than an oil- or gas-fired unit.

Request a Custom Quote Solid Fuel vs Oil/Gas
700–14,000
Rated Power
kW (60–1,200 ×10⁴ kcal/h)
320°C
Max Working Temp
High-temperature process heat
1.1 MPa
Design Pressure
Low pressure at high temp
76–85%
Thermal Efficiency
Rising with capacity
The Core Decision

When Solid-Fuel Thermal Oil Is the Right Choice

A coal/biomass fired thermal oil boiler fits two conditions at once: a process needing high-temperature indirect heating (typically 180–320°C) rather than direct steam, and a site with stable, low-cost solid fuel that can support the infrastructure solid fuel requires. The lower fuel cost is the reason to choose it; the cost is a larger footprint, more installation complexity, slower load response, and lower efficiency than an oil/gas unit.

Choose Solid Fuel When

  • Local coal or biomass is significantly cheaper than oil or gas after accounting for the lower efficiency over your operating period
  • The process needs high-temperature indirect heating (180–320°C) — chemical, asphalt, textile, wood-panel, edible oil, plastics — not direct steam
  • The site can accommodate fuel storage, ash handling, dust collection, and a chimney meeting local dispersion requirements
  • Heat duty falls within 700–14,000 kW and maximum temperature stays within the 320°C rating and the selected oil's limits

Choose the Oil/Gas or Steam Alternative When

  • The fuel-cost gap is small, site space is limited, or you need faster load response — the oil/gas fired thermal oil boiler fits better
  • Local regulations restrict coal firing — the EU Medium Combustion Plant Directive sets SO₂, NOx, and dust limits that can make coal projects difficult; biomass often remains viable where coal does not
  • The process needs steam directly — sterilization, humidification, or direct steam injection require a steam boiler
  • The required temperature exceeds 320°C, needing a different medium such as molten salt

The most common misjudgment we see is comparing fuel cost on paper without accounting for the lower boiler efficiency, the heating-surface fouling that erodes that efficiency over a cleaning cycle, and the site infrastructure and dual-side maintenance the system requires. Working through the full operating picture — fuel, ash, dust, thermal oil replacement, and cleaning — at the engineering stage gives a realistic comparison against the oil/gas alternative. Confirm your fuel economics, site capability, and local permitting before committing to solid fuel.

Technical Data

Rated Parameters and Output Range

Full output range for this series. All models share a design pressure of 1.1 MPa and a rated maximum working temperature of 320°C. Fuel consumption and circulation flow are design reference values confirmed against your fuel sample data before order.

EPCB coal biomass thermal oil boiler chain grate and closed-loop coil system layout

Chain Grate Firing into a Closed Oil Loop

The EPCB chain grate thermal oil boiler is a complete high-temperature heat-transfer solution built around solid fuel. Fuel is fed automatically and burns continuously across staged combustion zones on the chain grate, giving stable combustion and reliable heat from wood chips, biomass pellets, coal, and similar solid fuels. That heat is transferred to thermal oil circulating in a closed coil — pumped through your process loop rather than driven by pressure, which is why the system reaches 320°C at only 1.1 MPa.

A working system is more than the heater. It typically includes the circulation pump, an expansion tank to take up the oil's expansion, the thermal oil charge, an oil storage tank, an intelligent PLC control system, the fuel feeding system, ash removal, and flue gas treatment. EPCB designs, sizes, and supplies all of this as one integrated package during engineering — so the equipment is matched to your fuel and process for efficient, reliable, and safe operation.

Rated Power (kW) Heat Output (10⁴ kcal/h) Thermal Efficiency Circulation Flow Thermal Oil Charge Electrical Load
7006076%80 m³/h0.61 m³28 kW
1,0008076%100 m³/h0.78 m³40 kW
1,20010076%100 m³/h0.97 m³48 kW
1,40012078%100 m³/h1.12 m³55 kW
1,90016082%160 m³/h1.70 m³75 kW
2,30020083%160 m³/h2.60 m³77 kW
2,90025083%200 m³/h3.00 m³100 kW
3,50030083%200 m³/h3.20 m³100 kW
4,10035083%200 m³/h3.50 m³120 kW
4,70040083%260 m³/h4.10 m³140 kW
5,90050084%300 m³/h4.60 m³175 kW
7,00060084%340 m³/h6.20 m³215 kW
8,20070084%400 m³/h8.90 m³215 kW
9,40080084%520 m³/h12.60 m³270 kW
12,0001,00084%500 m³/h13.60 m³315 kW
14,0001,20085%620 m³/h14.80 m³380 kW

Read the efficiency figure correctly. The 76–85% values are rated boiler thermal efficiency under standard design conditions, rising with capacity. This is not combustion efficiency — combustion efficiency measures how completely the fuel burns and is a higher number, while boiler thermal efficiency is lower because it accounts for the flue gas and ash-related heat losses combustion efficiency ignores. These figures are also lower than an oil/gas thermal oil boiler (typically 92–93%) — the central trade-off: solid fuel usually costs less per unit of heat, but the boiler converts less of that energy into useful heat. Whether the net economics favour solid fuel depends on your local fuel prices over the operating period.

Rated Power (kW) Coal (kg/h) Biomass (kg/h) Main Pipe DN Weight (ton) L × W × H (mm)
700121.7175.8100—4,385 × 2,150 × 4,650
1,000162.2234.4125—4,685 × 2,500 × 4,900
1,200202.8293.0125—4,685 × 2,500 × 5,210
1,400237.1342.6125—4,685 × 2,500 × 5,710
1,900300.7434.6150256,000 × 2,200 × 4,300
2,300371.3536.6150326,400 × 2,400 × 4,800
2,900464.2669.1200335,700 × 2,400 × 5,070
3,500558.7805.0200397,000 × 2,850 × 5,200
4,100649.8939.2200417,600 × 2,900 × 5,400
4,700724.71,073.3200678,900 × 3,290 × 5,750
5,900917.31,325.7250708,900 × 3,290 × 6,000
7,0001,100.81,590.82508010,000 × 3,310 × 5,850
8,2001,284.21,856.02509811,000 × 3,400 × 5,850
9,4001,467.72,121.130010811,220 × 3,560 × 5,850
12,0001,834.62,651.430011512,610 × 3,560 × 5,850
14,0002,175.63,144.235013011,350 × 3,950 × 9,000

Coal figures are consistent with a calorific value of about 27 MJ/kg (good-grade bituminous), biomass figures with about 18–19 MJ/kg (relatively dry biomass). Real fuels often fall below these: wet wood chips, bagasse, or high-moisture residues have lower calorific value and require higher mass flow, potentially a larger feeding system and more frequent ash cleaning. The thermal oil charge (0.61–14.8 m³) steps up sharply between the 8,200 kW (8.9 m³) and 9,400 kW (12.6 m³) models — confirm the charge and its cost near this boundary. Shipping weight is not listed for 700–1,400 kW models; confirm during delivery planning. Larger units exceed 100 tons and ship in sections — plan site access, foundation, and lifting early. Electrical load powers the grate drive, draft fans, circulation pump, and controls — not the heat output. For output above 14,000 kW or temperatures beyond 320°C, a separate engineering review applies.

Fuel & Fouling

Solid Fuel Quality, Heating-Surface Fouling, and Thermal Oil

Fuel quality governs whether combustion is stable and whether the heater reaches rated output — and solid fuel introduces a consideration oil/gas thermal oil boilers do not have: ash fouling on the heat transfer surfaces, which erodes efficiency over time unless managed.

Coal Quality (Class II/III Soft Coal)

The design assumes Class II/III soft coal — generally suitable bituminous grades — subject to confirmation of calorific value, volatile matter, ash, sulfur, moisture, and particle size from a sample. Coal sulfur adds a cold-end concern: as flue gas cools across heat recovery surfaces such as an economizer, sulfur can drive low-temperature acid-dewpoint corrosion, so sulfur content should be confirmed and the cold-end design checked against it.

Biomass Quality (Moisture Dominant)

For biomass, moisture content is the dominant variable alongside calorific value and ash. Wood chips, pellets, and rice husk each behave differently and should be specified with a fuel sample analysis. Rice husk's high-silica ash and certain biomass ash chemistries foul faster. Provide the seasonal moisture range, not a single value, so the design covers worst-case conditions. Mixed-fuel firing is possible but must be defined at the design stage.

Heating-surface fouling is the solid-fuel efficiency trap. Combustion ash deposits on the heat transfer surfaces, and as fouling builds, heat transfer to the thermal oil declines — lowering efficiency and raising flue gas temperature. The deposit rate depends on your fuel's ash content and composition, so periodic heating-surface cleaning is part of normal operation, at intervals set by your fuel.

When buyers select solid fuel for its lower cost without planning for fouling-related cleaning and efficiency decline, the realised economics fall short of the on-paper fuel saving. Building the cleaning regime into the operating plan from the start avoids that gap.

Thermal Oil — A Selection Variable in Its Own Right

This series is rated for 320°C maximum working temperature, but the selected oil must also stay within its own maximum bulk and film temperature limits — film temperature at the coil wall exceeds the bulk outlet temperature, and exceeding the oil's film limit causes cracking and carbon deposits inside the coil. The oil's flash point, fire point, and auto-ignition temperature should be reviewed during selection. Mineral oils are economical to their rated limits; synthetic oils tolerate more at higher cost. The right oil depends on how close your operating temperature runs to these limits.

Site & Emissions

Site Prerequisites and Emissions Compliance

Solid fuel firing requires site infrastructure that oil/gas thermal oil boilers do not. These prerequisites sit on the installation critical path and should be confirmed before the purchase order is issued.

Fuel Storage & Feeding

A covered fuel storage area sized to your operating schedule and a feeding system to the grate. Biomass specifically requires covered dry storage — moisture absorption raises effective moisture content and degrades combustion.

Ash Handling & Chimney

An ash and slag handling system, and a chimney meeting local dispersion requirements. Larger units ship in sections and exceed 100 tons — site access, foundation, and lifting should be planned early.

Dust Collection to Local Limit

Coal and biomass combustion produces SO₂, NOx, and particulate matter. Dust collection — cyclone, bag filter, or electrostatic precipitator — is specified to your local particulate limit and the ash characteristics of your fuel.

For coal firing, confirm permitting before ordering. A new coal-fired installation may not be permitted at every site, and permitting can be the longest item on the project timeline. The EU Medium Combustion Plant Directive does not ban coal firing but sets SO₂, NOx, and dust limits that can make coal projects commercially or legally difficult unless met, and some industrial zones enforce clean-fuel mandates. We size the dust collection and chimney once the applicable emissions framework is established.

Safety & Maintenance

Dual-Side Safety, Oil Maintenance, and Standards

This product carries two safety dimensions that must be managed together — the thermal oil side and the solid-fuel combustion side. Operating maintenance is therefore more involved than for an oil/gas thermal oil boiler: you maintain both.

Thermal Oil Side

Over-temperature protection, flow and level monitoring, and a low-flow interlock — because low circulation lets film temperature climb and can start a cracking-and-fouling cycle, and because thermal oil is combustible, a high-temperature leak is a fire risk. The expansion tank includes overflow and drain provisions; nitrogen blanketing can be specified for high-temperature operation to reduce oil oxidation.

Solid-Fuel Side

Combustion controls, ash handling, and the heating-surface fouling management described above. The cleaning regime is set by your fuel's ash characteristics and is part of normal operation — not an exception — so it belongs in the maintenance plan from commissioning.

Thermal Oil Replacement

Thermal oil degrades over time through thermal stress and oxidation and is replaced when sampling shows it past acceptable limits — a recurring cost alongside fuel and ash handling. Periodic sampling for viscosity, acidity, and carbon residue is part of routine operation.

On standards: for the EU, confirm whether PED 2014/68/EU applies to pressure equipment and assemblies above 0.5 bar and the CE conformity scope for the heater body, expansion tank, piping, and safety devices. For US/ASME markets, confirm whether the applicable ASME section applies to the heater body and auxiliary pressure components, plus local registration. For fire safety, review NFPA 87 (Fluid Heaters) or the local equivalent. Confirm SO₂, NOx, and particulate air-permit limits before dust collector and chimney design. ISO 9001 reflects the manufacturer's quality system and is not a substitute for product-level compliance — request the certificate referencing your specific model.

Why EPCB

Engineering & Operating Advantages

For solid-fuel high-temperature indirect heating, four characteristics determine whether the system delivers its fuel-cost advantage reliably over its life — temperature reach at low pressure, fuel-matched grate firing, fouling-aware heat-surface design, and integrated dual-side control.

Thermal oil coil delivering 320 degrees C at low 1.1 MPa pressure in a solid fuel heater
01

320°C at Just 1.1 MPa Design Pressure

Because loop pressure is set by circulation rather than temperature, the system reaches 320°C at 1.1 MPa — delivering high-temperature heat without the high-pressure vessel risk a steam system faces at the same temperature, while running on low-cost solid fuel.

Chain grate stoker firing coal or biomass through staged combustion zones
02

Fuel-Matched Chain Grate Firing

Fuel burns on a chain grate through staged combustion zones with controlled air supply, configured to your coal grade or biomass type. Grate, feeding system, and air distribution are set against your fuel sample so combustion is stable at rated output — including coal, wood chips, pellets, and rice husk.

Heat transfer surfaces and economizer designed for ash fouling and cleaning access
03

Fouling-Aware Heat-Surface & Cold-End Design

Heat transfer surfaces and cleaning access are designed for the ash fouling solid fuel produces, and the cold-end design is checked against coal sulfur to guard against acid-dewpoint corrosion at the economizer — protecting the efficiency the fuel saving depends on.

Integrated control system managing thermal oil circuit and solid fuel combustion
04

Integrated Dual-Side Control

One control system manages both the thermal oil circuit — over-temperature, flow, and low-flow interlock to protect the coil — and the solid-fuel combustion side. Heater, grate, pump, expansion tank, dust collection, and controls are supplied as one engineered package sized to your loop, not assembled from mismatched parts on site.

Compliance

Certifications: Coverage Scope & How to Verify

Certification depends on the destination market, design pressure, and applicable pressure-equipment and fire-safety rules. ISO 9001 reflects the manufacturer's quality system — it is not a substitute for product-level pressure or fire-safety compliance. Request the certificate referencing your specific model and design pressure.

ISO 9001 quality management certificate for EPCB boiler manufacturing
ISO 9001 — Quality Management System
CE PED declaration document for eligible coal biomass thermal oil boiler configuration
CE / PED — Eligible EEA Configurations
EAC conformity certificate for thermal oil boiler export to Eurasian Economic Union markets
EAC — Applicable EAEU Markets
SGS boiler supplier assessment certificate for EPCB industrial boiler
SGS Boiler Supplier Certificate

What to confirm for your market. For the EU, confirm whether PED 2014/68/EU applies to pressure equipment and assemblies above 0.5 bar and the CE conformity scope for the heater body, expansion tank, piping, and safety devices. For US and ASME markets, confirm whether the applicable ASME section applies to the heater body and auxiliary pressure components, plus local pressure-equipment registration. Review NFPA 87 or the local fluid-heater standard for fire and explosion safety, and confirm SO₂, NOx, and particulate air-permit limits before dust collector and chimney design. For Southeast Asian, South Asian, Middle Eastern, and African markets, import registration varies by country — confirm before issuing the purchase order. Third-party inspection by Bureau Veritas, SGS, or TÜV can be arranged before dispatch on request.

Procurement Workflow

Delivery Process & What Affects Lead Time

Every custom coal/biomass thermal oil boiler system from EPCB moves through defined engineering stages, with client sign-off on drawings before manufacturing begins. Because this is a solid-fuel system, fuel quality assessment and site/permitting readiness join the critical path early.

1
Process, Fuel & Economics Assessment Critical Gate

Confirm process heat duty, maximum temperature, and whether the process needs thermal oil or steam; then confirm fuel economics — local coal or biomass price versus oil/gas after the lower efficiency — to verify solid fuel is the right choice.

2
Fuel Sample & System Sizing

Analyse fuel sample data (calorific value, volatile matter, ash, sulfur, moisture, particle size) to set grate, feeding, ash handling, and cleaning interval; size pump, expansion tank, oil charge, and dust collection to your loop and emissions limit.

3
Permitting & Site Readiness Often the Longest Item

Confirm coal-installation permit status and emissions framework; plan covered fuel storage, ash handling, chimney, foundation, and section lifting for units over 100 tons. Permitting can be the longest item on the timeline — start it early.

4
Engineering Drawing Approval

System drawings issued for client review and written approval before manufacturing begins. Changes after sign-off affect lead time and cost.

5
Manufacturing, Testing & Inspection

Heater, grate, and system components manufactured and tested; pressure and safety-device checks performed. Bureau Veritas, SGS, or TÜV inspection before dispatch where the market or project requires it — include in your inquiry so it is scheduled.

6
Delivery & Commissioning Guidance

Support for sectional delivery and on-site reassembly, oil charging and first-heat dehydration, combustion setup, and commissioning of both the oil and solid-fuel sides.

The two delays that matter most are coal-installation permitting and the construction of fuel storage, ash handling, and dust collection — both on the critical path and both best started before manufacturing rather than after the heater ships. A site and permitting checklist is part of the scoping output so the timeline is visible from the start.

Inquiry Inputs

What to Confirm Before Requesting a Quote

An accurate quotation is possible once the following are confirmed. Without them, any price or lead-time figure remains conditional.

01
Heat Duty & Max Temperature

Process heat duty (kW or kcal/h) and maximum process temperature (°C), with margin below the 320°C rating.

02
Outlet & Return Oil Temperature

So system ΔT matches the circulation flow and your process loop.

03
Thermal Oil or Steam?

Confirm the process needs indirect high-temperature heating, not direct steam — the first fit question for this product.

04
Fuel Type & Quality

Coal grade (Class II/III soft coal as standard) or biomass type, with calorific value, volatile matter, ash, sulfur, moisture, and particle size from a sample.

05
Fuel Economics

Local coal or biomass price versus oil/gas, after accounting for the lower efficiency, to confirm solid fuel is the better choice over the oil/gas alternative.

06
Site Capability & Permit

Area for fuel storage, ash handling, dust collection, and chimney; and coal-installation permit status for your site.

07
Emissions Limits & Thermal Oil

Local SO₂, NOx, and particulate thresholds to size dust collection; plus mineral or synthetic oil preference and budget for the charge (0.61–14.8 m³ by model).

08
Electrical Supply & Market

Capacity for grate, fans, pump, and controls (28–380 kW by model); and applicable PED/CE, ASME, NFPA 87, air-permit, and registration requirements for your market.

FAQ

Frequently Asked Questions

Why is the efficiency lower than an oil or gas fired thermal oil boiler?

Solid fuel combustion carries higher flue gas and ash-related losses than oil or gas, so rated boiler thermal efficiency runs 76–85% here (rising with capacity), versus 92–93% for an oil/gas thermal oil boiler. Note that boiler thermal efficiency is not the same as combustion efficiency, which measures how completely the fuel burns and is a higher figure. Buyers choose solid fuel for its lower cost per unit of heat, accepting the lower efficiency and added site complexity; whether the net economics favour solid fuel depends on local fuel prices.

What fuel analysis is required before ordering?

For coal, confirm calorific value, volatile matter, ash, sulfur, moisture, and particle size against the Class II/III soft (bituminous) coal the design assumes. For biomass, provide moisture content, calorific value, ash content and composition, and particle size from a fuel sample. These determine grate configuration, feeding system sizing, ash handling, and the heating-surface cleaning interval, so they should be confirmed before manufacturing.

Can it use wet wood chips or high-moisture biomass?

It can, but wet fuel has a lower calorific value, so consumption rises above the table figures and the feeding system, grate, and ash cleaning regime may need to be sized accordingly. If your biomass regularly exceeds the design moisture threshold, covered storage with air drying or a pre-drying stage may be required. Provide the seasonal moisture range, not a single value, so the design covers worst-case conditions.

What emissions equipment is required?

Coal and biomass combustion produces SO₂, NOx, and particulate matter, so dust collection — cyclone, bag filter, or electrostatic precipitator — is specified to your local particulate limit and your fuel's ash characteristics. The configuration is sized once your emissions framework is known. Confirm your local thresholds at the inquiry stage so the dust collector and chimney are designed correctly.

Should I choose this or the oil/gas fired thermal oil boiler?

Choose solid fuel when local coal or biomass is significantly cheaper than oil or gas after accounting for the lower efficiency, and your site can support fuel storage, ash handling, dust collection, and a chimney. Choose oil/gas when the fuel cost difference is small, site space or infrastructure is limited, you need faster load response, or local regulations restrict coal firing. Share your fuel prices and site conditions and we will help you compare.

Before Selecting

Confirm Fuel Economics, Site Capability, and Process Temperature First

Whether a coal/biomass fired thermal oil boiler is the right fit comes down to four conditions: a process needing high-temperature indirect heating within the 320°C rating, a heat duty within the 700–14,000 kW range, local solid fuel genuinely cheaper than oil or gas after the lower efficiency, and a site that can support solid fuel storage, ash handling, dust collection, and emissions compliance.

The most common misjudgment we see is comparing fuel cost on paper without accounting for the lower boiler efficiency, the heating-surface fouling that erodes it, and the site infrastructure and dual-side maintenance the system requires. Working through the full operating picture — fuel, ash, dust, thermal oil replacement, and cleaning — at the engineering stage gives a realistic comparison against the oil/gas alternative and avoids a shortfall after commissioning.

To begin, share your process heat duty, maximum process temperature, required outlet/return oil temperatures, fuel type and sample data, and site conditions — along with your local fuel prices for a comparison against the oil/gas thermal oil option. If a certification, emissions framework, or coal-installation permit applies, include that in your first message.

Talk to an Engineer
  • Process heat duty — kW or kcal/h, plus max temperature below 320°C
  • Outlet / return oil temperature — to match system ΔT and flow
  • Fuel type & sample data — coal grade or biomass, with full analysis
  • Fuel economics — local solid fuel price vs oil/gas after efficiency
  • Site capability & permit — storage, ash, dust, chimney, coal permit
  • Emissions limits & thermal oil — SO₂/NOx/PM thresholds, mineral/synthetic, oil charge budget

Get Instant Quote

When you’re looking for custom industrial boiler solution or service, we are always here repond to your quote as soon as possible.

Contact Form epcb