Thermal oil heaters
PIROBLOC thermal oil heaters are adapted to the regulations in force in every territory. We manufacture high range, totally customized thermal fluid heaters to satisfy our customers’ needs:
- Horizontal or vertical execution. There is no functional difference between a horizontal thermal oil heater and a vertical thermal fluid heater, with the choice being made according to the available space and height in the plant, and ease of maintenance.
- Our hot oil boilers provide heat through liquid fuel (HFO, light oil) and/or gaseous (natural gas, propane, etc.). A thermal oil boiler is the main component in a thermal fluid heating system, where a liquid fuel is heated and circulated to provide energy to different energy users within a closed circuit.
- Features: Automatic running of the heater and indirect surveillance.
A hot oil heating system has numerous benefits, being the following the main ones:
- Safety. Our thermal fluid heaters operate without pressure and water. This avoids the typical problems related to steam heating systems, such as leaks, corrosion, water treatment, etc.
- Thermal oil heaters require low maintenance.
- Fuel savings up to 20% compared to steam heating systems. A thermal fluid system consists of a closed circuit with minimum energy leaks. At least 90% of the fuel is used in the heating process.
- Hot oil heating systems are highly efficient thanks to the temperature uniformity through all the production process.
- Power range: From 0,1 to 15 MW
- Admissible maximum pressure (PS): 40 bar
- Test pressure (PT): 60 bar
- Service maximum pressure (PMS): 25 bar
- Service temperature: till 400ºC
- Design temperature: 400ºC
- Two coils, three smoke passes
- Fluids content: thermal fluids. Group 1
- Surveillance system: Indirect
- Control interval: till 24 hours
- Class according with Directive 2014/68/UE
- Design Code: ASME VIII, Div 1, EN 13445, AD 2000, etc.
- Allweiler thermal fluid pump
- Weishaupt burner
- Control panel with Siemens/Télémécanique PLC and touch screen
- Wika pressure transmitters
- Ari valves
- Temperature up to 400º C
- Folding doors
- Fire prevention inlet for N2 or steam
- Remote assistance
- ATEX execution
- “Custom” executions
Applications of a thermal fluid system
- Warm asphalt / bitumen
- Storage tanks / port terminals
- Adhesives and glues
- Plastic and rubber
- Chemistry industry
- Oils and fats
- Drying processes
- Wood drying
- Distillation columns
- Solar energy
- Stamping tunnels
- Flexography and gravure
- Inks drying
- Industrial bakery
- Heating of ironers
- Sludge drying
- Meat industry
- Industrial pastry
- Aviation industry
- Research centers
Operation of the thermal oil heater
Our thermal oil heaters are of cylindrical shape, arranged to raise the temperature of the thermal fluid circulating in two concentric coils by combustion of liquid fuel in a burner located in the front cover. There is high density rockwool insulation between the two casings for low temperatures (30-40°C) in the outer casing, thereby achieving minimal structural losses and preventing burns from unintentional contact with the boiler.
The burner flame is projected therefrom to the combustion chamber, which has been sized according to the geometry of the flame. The closing of the chamber is done by refractary. It then changes direction and the combustion gases circulate at high speed and turbulence between the two coils to the front cover, where they change direction again until evacuated by the flue at the end of the casings.
The coils are made up of two, three, four or more steps depending on the model; as high-speed flow of the thermal fluid is essential for good heat transfer and to prevent it cracking.
Initially, the thermal fluid circulates in the outside coil (where the heat is transmitted almost exclusively by convection) before transferring to the internal coil (where the heat is transmitted almost exclusively by radiation), thus achieving excellent energy performance.
The inside part of the front cover closes the gas flue between the coils and has holes for the passage of the coil tubes to be connected to the general collectors, connected to the circuit by flanges.
It also closes the combustion chamber where the burner is fixed. It is equipped with a manhole for access to the combustion chamber if necessary.
PIROBLOC is one of the pioneers in the manufacture of thermal oil boilers. Extensive knowledge of this technology and our belief in innovation have enabled us to develop our own design, which takes all the important technical parameters into consideration, as well as offering a vertical arrangement which is a perfectly valid alternative to the conventional horizontal configurations on the market.
Simulations before installation of the boiler
In the design of a thermal fluid heater, hydraulic and thermodynamic simulations of it are important, under certain conditions previously provided by the customer. To ensure that we satisfy every customer’s needs, we carry out the correct calculations of chimneys in relation to the combustion chamber and dimensioning of the boiler system tubing, as well as thorough calculations for the pressurised body and its curvature.
Furthermore, proper thermal insulation of the boiler body will prevent heat losses and make the whole system more efficient, as well as saving fuel.
Siting of a thermal fluid heater
When an industrial plant is new and the roof has not yet been put on and when the boiler is of notable size, it is normally put in taking advantage of this lack of a roof. To avoid having to remove part of the roof at a later date for future repairs to the boiler or even for it to be dismantled, we recommend leaving an opening large enough for it.
Being a thermal oil heater, its definitive placement can be near the consumer and/or work area of the personnel in charge of its supervision and maintenance. This would lead to economic savings in terms of installation materials and time used by your personnel for its control.
The fuel used is another matter to be taken into account before deciding on the boiler’s location.
- If natural gas is used, basements must be avoided, otherwise installation of forced ventilation will be necessary to facilitate its combustion.
- If diesel fuel or fuel-oil is used, at minimum a fuel accumulation tank will be needed, so that the nearer the boiler is placed to the main tank, the greater the possibility of avoiding installation of an intermediate or supply tank.
Other elements to be taken into account necessary for the whole circuit to function well are the expansion tank and chimney, which should project a minimum of 1 m above its surrounding buildings in a radius of 10 m from the chimney shaft.
Pirobloc offers the option of incorporating adjustable-speed drives in the main pumps of the thermal fluid system. This adjustable-speed drive in the motor of a thermal fluid pump enables important savings to be produced in energy consumption and economic cost, because the greatest electricity consumption in thermal fluid systems normally occurs in the motor of the main pump.
A variable-frequency drive can reduce energy consumption by up to 60% by adjusting the speed of the motor. For example, a centrifugal pump working at 80% speed only consumes half the energy of one working at full power.
A variable-frequency drive also provides the following advantages:
- It improves control of flow and pressure.
- Corrects the motor’s power factor.
- Eliminates reactive energy.
- It enables relatively large motors to be started, avoiding the star-triangle system.
- Reduces maintenance.
- Reduces system vibrations to a minimum.
Another technique adopted for energy efficiency is the use of digital modulating burners with continuous oxygen control. With this improvement, an increase in efficiency of the order of 2% achieved, with the consequent fuel saving. In addition, this system enables reduced emissions of combustion products and greater operating safety.
With its associated controller, the burner is responsible for optimum regulation of the amount of fuel and air for combustion. It is a system which keeps oxygen proportions to a minimum, guaranteeing optimum efficiency without unburned residues and safe combustion.
The system consists of a continuous oxygen analyser placed in the chimney of the thermal fluid heater. This O₂ probe constantly informs the digital combustion controller which maintains the oxygen supply to the burner as low as possible within safety levels.
The burner management system optimises the fuel – oxidiser mixture. The purpose of this BMS is digital control of combustion to keep it within optimum parameters to achieve maximum efficiency. This BMS establishes the right position of the burner servo motor.