OMP and HTH Multitubolar Thermal Oil Heaters

Patented multitubular structure composed of a parallelepiped-shaped combustion chamber fully screened by tangent tubes (total absence of refractories) overlying on a convective section.
A wide range of thermal capacities and the optimization on market requests make these heaters ideal for applications which requires medium-big thermal capacity.

The internal structure of these boilers is a multitubular design with a large combustion chamber. Bundles of pipes bent at an angle of 90° pass through holes in two walls of the portal-shaped collector. Pipe connections are made by arc welding by qualified welders. The convective pipes and the combustion chamber are placed in a thermally insulated stainless steel case, the burner is connected to the boiler, and the fittings and measuring instruments necessary for operation are installed.

In addition, the heater is supplied packaged, with the air preheater integrated on the front side.

Due to the convective tube bundle and large combustion chamber, OMP, and HTH heaters provide large heating surfaces with a small footprint.

The geometry of the combustion chamber allows a large space for flame development and results in low thermal loads. As a consequence, very low NOx emission levels can be achieved, even with combustion air preheating.

Heaters of these series have a large heating surface, due to the geometry of the convective tube bundle, working in counter-flow and the large radiant section, completely screened by tubes.

Inspection doors around the heater ensure easy access to the pressure parts, to reduce downtime for maintenance or repair operations. The absence of a refractory wall at the back reduces extraordinary maintenance events drastically, making these heaters particularly suitable for the combustion of heavy fuel oil, which requires frequent cleaning of internal parts and can damage refractory walls.

The thermal oil enters the convective section, at a lower temperature and only later goes into the hotter radiant section, reducing thermal shocks on the oil, especially during start-up. The absence of refractory walls on the back does not allow unwanted heat transfers from refractory to oil when the plant shuts down. Such transfers with no circulation could cause cracking of the thermal oil.

After assembly, each boiler is subjected to a series of industrial tests that simulate the operating conditions of the customer.


  • Compact modular design: these boilers are delivered as a fully equipped and ready-to-connect boiler, minimizing on-site installation work.
  • Ease of maintenance: inspection hatches provide easy access for inspection, cleaning, and service operations. In boilers operating on heavy fuels, automatic soot blowers are provided to clean the furnace from combustion products.
  • Design and manufacturing realized according to the most important international standards CE-PED, ASME, RTN, SELO.
  • Low NOx emissions less than 80 mg/m3 due to an optimized combination with any market burner (according to BAT).
  • Combustion system suitable for different fuels.
  • Multitubular boilers are designed and built according to the customers‘ requirements and can be adapted to work with high heating medium temperatures or for applications where higher than standard power is required.
  • High thermal efficiency – up to 93% – due to the use of a countercurrent heat exchange scheme in the convective section and the presence of a built-in air combustion preheater in front of the burner.
  • Intelligent system for monitoring operating parameters and boiler control with the ability to integrate into a single complex with automation of technological lines.
  • Long service life due to a balanced design with smooth heating of the fluid during cold starts and protection against thermal shocks in the radiator pipes.

Key Features:

  • Thermal Capacity: 1.7 – 40 MW
  • NOx Emissions: 80 mg/Nm3 (lower valves on request)
  • Temperature: Up to 752°F
  • Efficiency: Up to 93%