Process Heaters

Circulation heater is a combined unit of an Electric heater bundle inserted inside a Pressure vessel or shell, in which fluid will be flowing continuously. It is a compact heating system with fast heating of the process fluids.

The Circulation heaters are designed in such a way that cold process fluid enters the pressure vessel through inlet nozzle at a low temperature, passes though the active zone of the heater bundle and leaves the vessel through outlet nozzle at desired high temperature. The system is designed in such a way that heating element skin temperature and the pressure drop across the nozzles are maintained within permissible limits. The Circulation heater system can be designed in single stage vessel or multi-stage vessels based on the process requirements.   The System can be installed vertically or horizontally based on the requirement and space availability.

Advantages

• Environment-friendly design. No hazardous gas / smoke/ emission from the system.
• Compact design for quick heating of continuous flow.
• Can be used for short duration operation as well as continuous operation.
• Precision Temperature control
• Can be accommodated in small foot prints.
• Custom designed to meet specifications.
• Highly energy efficient and provide maximum dielectric strength.
• Compatible with standard industry piping and safety standards.
• Reliable design
• Easy to operate and maintenance-friendly
• Energy Saving
• Heating Element: Mineral filled insulated Heating Elements or Tubular heating Elements with Ni-Cr (80-20) as heating Coil and suitable outer sheaths
• Control System: Thyristor control Panel + Local control Stations for effective temperature control & safe operation. ( Safe area  or Hazardous area)
• Protection and Control: Element Skin Temperature controls, Process temperature control, Earth leakage protection, Overload current protection

Construction
Typical Circulation heaters are made of below-listed parts.
Terminal Enclosures — The Design of terminal enclosure changes based on the area of installation (Safe or hazardous). The Terminal enclosure is designed to protect the terminals of the individual elements from external impact, such as dust, moisture etc and to facilitate the connection of Incoming power supply to the heater bundle. Marathon flameproof heaters are certified to install in hazardous area zone 1 &2,Gas group IIC,IP 66

Heater Bundle : Consist of No. of  U Pin heating elements adequately supported by set of Baffles & Tie rods, designed to deliver the specified temperature at outlet by maintaining the element temperature & pressure drop within the safe limits. Heating elements can be fixed to heater flange by means of standoff sleeve pipes with brazing or by direct welding or by means of threaded couplings. Heat duty of a bundle can be divided in to many sub groups (banks) based on process conditions. This will help in better control as flexibility in the operation.

Pressure Vessel: Pressure Vessel or heater housing is a fabricated shell in accordance with ASME or equivalent international standards. The Vessel has a inlet and outlet nozzle for the process fluid to flow. The Vessels are also provided with a drain & vent nozzle for the maintenance & safe operation purpose. The Vessel can be designed for either horizontal or vertical installation with single stage or multistage configuration. It is recommended to have the vessel insulated so as to avoid excess heat loss and also to protect from any thermal shock.

Temperature Sensors: The Heater bundle will have Element skin temperature sensor for monitoring and regulating the Element skin temperature within the limits.  The Unit may also need additional sensors such as Tube sheet Temperature Sensor, Terminal Box Sensor, vessel Body temperature sensor and process fluid Temperature sensors based on case to case. The Sensors used for the system will be certified in accordance with the area of installation.

The Temperature sensors are Typically RTD or Thermocouple. A simple heater bundle can also be controlled using Thermostat protection for skin & process temperature. If the Operation pressure is High, It is recommended to have a PSV (Pressure safety Valve) installed within the Heater Vessel as an additional safety measure.

Control Panel: Heater controls Panel are designed to monitor & control the operations of the heater bundle also to ensure the safety of the equipment and operations.

The control logic can be either ON/OFF (contactor) or regulated (Thyristor) or combination of both in a single panel. The control panels can be installed in both safe area & hazardous area by following respective design guidelines & certification requirements.

The Control Panels are provided with various indication systems such as Power ON, Heater ON OFF, Trip, High Temperature etc for comfortable handling of the process. The Temperatures of Elements, Process fluid & other areas (with sensors) are displayed on the Panel for better monitoring & awareness. Control Panel will also have safety interlocks such as high element temperature, Earth fault, process over-temperature etc along with Emergency stop access for the safe operation and control.

Application Areas

• Oil & gas
• Refinery & petrochemicals
• Gas processing plants
• Air separation unit
• Power plants
• Oil heating skid
• Fuel gas /natural gas skids
• Vaporizers

Duct heaters are devices which are an assembly of multiple heating elements mounted in a plate or casing and used to heat the air in a non-pressurized condition. The Heater bundle is usually inserted inside a duct line or an insulated body through which air passes and get heated up to required temperature.

Duct heater elements can be of open coil, tubular or finned tubular heating elements, depending upon the application, temperature etc. If an application needs a very large capacity of heat duty, several smaller capacities the duct heater bundles can be made and assembled in series. This will help not only to get the desired temperature at varying process condition but also eases the job of maintenance and spares cost.

Features and Benefits

• Energy efficient
• Safe Design
• Environment friendly, No Hazardous smoke, NOx & SOx gas generation.
• Corrosion and oxidation resistance
• User-friendly system.Easy to install & operate.
• Durable and easy maintenance
• Rugged construction eliminates the hazard of electric shock
• The reinforced frame allows for minimum vibration
• Minimal heat loss.
• Very small footprints are required. Can be installed in any existing ducts with little access

Application Areas

• Air Drying Operations ( Paintings, pellets drying, drying application in Process)
• Air Handling Equipment
• Humidity control
• Comfort Air Heating for the building (HVAC)
• Core Drying
• Chemical pellets dry heating
• Booster Air
• Air Preheating
• Secondary heating
• Multi-zone Reheating
• Resistor Load Banks

Fuel Gas Heater Skids are sub-assembly of a complete fuel gas conditioning system or fuel gas filtration package skids. The heating systems are used to preheat the fuel gas to the desired temperature at a specified pressure and flow rate, prior to feeding to the actual process or further circulations.

The specially designed Fuel gas heating skids helps to monitor, regulate the gas flow with multiple safety features for the trouble-free and risk-free operation. The system is designed considering the incoming gas properties along environmental conditions to achieve the desired outlet flow conditions.

The skids are generally used for preheating the gas above its dew point, prior to feeding into the other equipment such as Gas operated turbines, generators or other process applications. The system can also be used for superheating the gas for other industrial applications.

Construction
Each fuel gas heater skid is custom made design to suit respective process specifications. A typical Fuel gas heater skid system consists of:-

• Electric Heater Bundle
• Pressure Vessel or housing for the heater bundle
• Control panel for the heater operation control
• Temperature sensors such as RTDs, Thermocouples, Temperature transmitters
• Pressure safety valve
• Valves for flow control
• Power & Instrument Wiring
• Skid base for easy installation at site

For any Production/process facility, when a large volume of fluid to be heated before pumping out to process application, the Immersion Heaters are always the best-recommended solutions. A single bundle or multiple smaller units can be installed in the Tank for the uniform heat transfer and steady heating of the fluid with all safety precautions in built within the heater and control system.

Some of the precautions to be taken while designing and selecting an Immersion heater are

• Selection of right material for the wet parts to avoid potential corrosion from the fluid to be heated.
• Proper cold length & active length ratio to avoid hot spots & dry heating.
• Element skin temperature within flash point limit of the fluid to avoid any hazard. A Proper thermal design is very much necessary whenever heating a flammable fluid or in hazardous area installation.
• Fixing method & support for the bundle considering the turbulence during the in & outflow.
• Control system for both element skin & fluid temperature.

Construction
Terminal Enclosure: Marathon flameproof heaters are certified to install in hazardous area Zone 1 & 2 , Gas group IIC, IP66. The Terminal enclosure is designed to protect the terminals of the individual elements from external impacts, such as dust, moisture etc and to facilitate the connection of the Incoming power supply to the heater bundle.

Heater Bundle: Consist of No. of U Pin heating elements adequately supported by set of Baffles & Tie rods, designed to deliver the specified temperature at outlet by maintaining the element temperature & pressure drop within the safe limits. Heating elements can be fixed to heater flange by means of standoff sleeve pipes with brazing or by direct welding or by means of threaded couplings. Heat duty of a bundle can be divided in to many sub groups (banks) based on process conditions. This will help in better control as flexibility in the operation.

Temperature Sensors: The Heater bundle will have Element skin temperature sensor for monitoring and regulating the Element skin temperature within the limits. The Unit may also need additional sensors such as Tube sheet Temperature Sensor, Terminal Box Sensor, vessel Body temperature sensor and process fluid Temperature sensors based on case to case. The Sensors used for the system will be certified in accordance with the area of installation. The Temperature sensors are Typically RTD or Thermocouple. A simple heater bundle can also be controlled using Thermostat protection for skin & process temperature. If the Operation pressure is High, It is recommended to have a PSV (Pressure safety Valve) installed within the Heater Vessel as an additional safety measure.

Control Panel: Heater controls Panel are designed to monitor & control the operations of the heater bundle also to ensure the safety of the equipment and operations. The control logic can be either ON/OFF (contactor) or regulated (Thyristor) or combination of both in a single panel. The control panels can be installed in both safe area & hazardous area by following respective design guidelines & certification requirements. The Control Panels are provided with various indication systems such as Power ON, Heater ON OFF, Trip, High Temperature etc for comfortable handling of the process. The Temperatures of Elements, Process fluid & other areas (with sensors) are displayed on the Panel for better monitoring & awareness. Control Panel will also have safety interlocks such as high element temperature, Earth fault, process over temperature etc along with Emergency stop access for the safe operation and control.

Advantages

• Heaters can be used for quick heating of small volume storages as well as for heating large volumes with longer operational hours
• Widely used for heating high viscous fluids ( Bitumen, HFO etc) and reduce the viscosity before pumping out
• Environment-friendly design. No hazardous gas/smoke/ emission from the system.
• Precision Temperature control
• Can be accommodated in small footprints.
• Custom designed to meet specifications.
• Highly energy efficient and provide maximum dielectric strength.
• Compatible with standard industry piping and safety standards.
• Reliable design.
• Easy to operate and maintenance-friendly.
• Energy Saving.
• No need to drain the tank for any repair/replacements in case of indirect Immersion Heaters.
• Heating Elements: Mineral filled insulated Heating Elements or Tubular heating Elements with Ni-Cr (80-20) as heating Coil and suitable outer sheaths.
• Protections & control: Element Skin Temperature Control, Process Temperature Control, Earth Leakage Protection Overload Current Protection, Temperature Class Protection ( for Hazardous area only)

Application

• At large Storage Tanks for preheating of thick fluids.
• Oil Heating (crude, Thermic fluids, and other Process fluids etc in storage tanks).
• Water heating applications & vaporizer System.
• For reducing the viscosity of the fluid and make it suitable for pumping out.
• Steam Boilers.
• Oil cooling systems & compression packages
• Edible oil heating for food industries.

Infrared radiant heaters are electric heaters specifically designed to emit infrared heat radiation, where heating by other means is not ideal. It is mostly usable application where movable object heat like float glass, movable mold heating and drying of paint etc. Different lengths and sizes are available to meet specifications. IR heaters are high intensity infrared radiation heaters and used where high temperatures are necessary. They are designed to work in large and exposed areas and heavy duty projects.

Construction

• Heating Element with high emissivity coating
• Stainless steel assembling plate & threaded studs for mounting
• Insulation fiber pad between element & plate
• Ceramic insulation bead between element & plate
• Terminal strip for connection

Application Areas

• Float glass heating
• Movable mold preheating
• Conveyor or batch type ovens, Drying, Curing
• Industrial applications with medium intensity infrared heat: Paint spray, Booths, Curing, and Drying Softening resins.
• High-intensity heat applications

Every industry in today’s world is utilizing the some or other form of heating applications. The heating is very much a part of our day to day life. As the dependency on heating application grows, there is a serious concern also expressed related to safety and environmental impact as well as efficiency of the many of the heating solutions being used. While some of the systems have a risk of fire accidents, many of the other conventional system generate a lot of carbon dioxide and other gases that contaminate the environment. Tubular Electric heater is a one of the Best option for the modern world, which is safest way to heat any fluid or surface without creating gases or hazardous releases.

Tubular heaters are typically manufactured using a resistivity coil placed inside a Metal tube and filled inside with insulating materials such as Magnesium oxide. The heating coil placed at the center with uniform pitches, separated from the outer metal sheath by a compacted Magnesium oxide ensures that No electric shock is transferred to the outer surface. At the same time the all the heat energy produced is transferred to the process through outer body. Hence the Heater is regarded as one of the highly efficient and safe way of heating.

Construction

• Nickel Chromium Resistance were uniformly coiled wire is stretched through the active length of the element. The ends are proved with the terminal pins to create cold ends.
• Magnesium oxide:High purity magnesium Oxide power is filled between the coil and outer tube in a automated filling station to ensure the right insulation, conduction as well as compactness.
• Outer sheath: Tube (welded or seamless) which acts as a outer protection for the heating Element. Selection of outer tube depends on various factors such as temperature, pressure, fluid to be heated etc.
• Terminal pins: Also known as terminal pins are extended ends of the heating elements. The SS rods of a specific diameter are fusion welded to the coils at both ends. The length of the rod depends on the nonheating length required for any application and installation.
• End Sealing: Sealing is done using the combination of Ceramic beads, soft seals & sealants. The sealing ensures that no moisture from the atmosphere enters the heating element and keeps it dry.

End Seal Options

• Teflon Seal: Teflon seal is used where effective sealing is required against moisture and oil contamination.
• Silicon Rubber Seal: Most popular and highly used sealing method. The sealing can withstand up to 200 deg C temperature and provides long lasting moisture protection.
• Epoxy Seal: Epoxy potting forms a good moisture seal with more mechanical strength than a silicon rubber seal. Recommended for a system assembly with large no of tubular elements.
• Cement: recommended for the heater which operates at very high skin temperature. Provides protection against high viscous fluids and dusts. The top layer can be provided with additional insulation to make it moisture resistance as well.