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solid model of electrically heated HTF plant


Dove Thermal Engineering is widely involved with the design and installation of hot oil heating systems, with plants recirculating synthetic thermal fluid, and the operation of high temperature thermal fluid heating facilities. The Klieverik calendering plant (illustrated) works Solutia T66 at temperatures to 340 deg.C under atmospheric pressure. Liquid Phase Heating and Hot Oil Heating shows our highly successful shell-and-tube electric HTF heaters for synthetic fluids and mineral oils have been configured as skid-mounted and installed systems serving production line equipment, chemical process sidestreams and biothermal conditioning stages. We provide lifetime support for both the equipment and the host process, and have built fired- and unfired plant & equipment for Therminol, Shell Thermia and Dowtherm thermal fluid heating installations.

Steam v Thermal Fluid Heating

At temperatures above 340 degrees or so, vapour pressures of even the most tolerant synthetic fluids tend to rise above atmospheric, so that - without careful management - the design and operating conditions of process heating systems can affect their useful working life. It may be reflected that steam at 300 deg.C raises a head just slightly below 85 bar(g). That said, a thermal fluid can also be operated above saturation pressure, given precautions to inhibit oxidation of the working medium, either by cooling the system expansion tank or nitrogen-blanketing the liquid surface.

Fluid Heating Options

Dove Thermal specializes in the application, design and manufacture of electrically-fired HTF heaters and heating systems. Electric firing offers very precise heat input and control, and location of heat source adjacent to application on the factory floor. Coil-type boilers fired by gas or fuel oil are best located away from production spaces, as may be required by statutory regulations and/or insurance considerations. There are instances where steam heating of heat transfer fluids offer a convenient and economical solution to local application requirements. As they do not require ventilation for combustion air supply, electrically-fired and steam-heated calorifiers are suitable for installation in airconditioned spaces and clean room environments.

System Pressures

Although synthetic fluid and hot oil systems can be worked either side of atmospheric pressure, pressurised installations allowing operation above their normal saturation temperatures are more complex than for steam. No thermodynamic pressure is induced during thermal fluid heating while its vapour pressure remains below atmospheric, and engineering costs are much-reduced if systems are to operate only under gravity head. Generally speaking, electric calorifiers for thermal fluid and hot oil heating fall within SEP classification of the PED and are not CE marked. We also design, build and commission jacketed vessels, calandria and externally recirculated batch heating vessels - and the host processes - for chemical and food production processes. Any of these may be arranged to work at normal pressure, while the vessels and their contents are raised well above atmospheric levels.

Materials of Construction

Carbon steel is the preferred structural material for thermal fluid heating equipment, given lower expansion coefficients – and better properties retention than stainless grades. Our shell and Tube thermal fluid calorifiers enable close approaches to saturation temperatures while maintaining liquid phase conditions at the boundary layer. This extends the fluid’s working life and assures accurate control of the process.


As mentioned elsewhere in these pages, Dove Thermal Engineering is a peer group management company providing engineering consultancy, plant-building, and millwrighting services. We have been designing and building heat transfer equipment for over thirty years, and hold the DTI's award for Excellence in Design Engineering and Project Management. Dove Thermal were specialist engineering design consultants to the Manufacturing and Design Advisory Services over their duration, with production plant, process design and product innovation as our core activities.

Links to related main site pages:

Liquid Phase and Hot Oil Heating

Process Heating Systems

Dove Thermal Products

Coolant Management Modules; Drying Tunnels
Steam-Heated Calorifiers; Thermal Oil Heaters
Shell-and-Tube Heat Exchangers; HTF Heaters
Thermal Fluid Heaters; HTF-Heated Calorifiers
Packaged Quench Plants; Air Handling Units
Balance-of-Plant Modules; Cooling Tunnels

Dove Thermal Services

Forensic Engineering; HVRAC Engineering
Consult-Design-Construct Services
Thermal Engineering Consultancy
Process Plant & Process Design
Thermal Fluid Heating Systems
Environmental Systems Design

Dove Thermal Engineering Limited
P.O.Box 5, Uttoxeter, Staffordshire,
ST14 8QX, United Kingdom

Telephone : 01889 569933