Infrared tunnels for multilayer polymer pipes

EUROLINIA’s engineering department can offer custom IR solutions for the following types of pipes:

• Acrylonitrile Butadiene Styrene (ABS)
• Polypropylene (PP)
• Polyvinyl Chloride (PVC)
• Chlorinated polyvinyl chloride (CPVC)
• Cross-linked polyethylene (PEX)
• High-density polyethylene (HDPE)
• Low-density polyethylene (LDPE)
• Teflon (PTFE)
• Other types upon request

Main advantages of EUROLINIA IR tunnel ovens include:

• Perfectly even heat distribution along the surface of the pipe
• High power density of IR radiation
• Temperatures of up to 800C
• Temperature accuracy of +-1C
• Controlled and clean environment
• High efficiency and speed of production
• Safe and instant stop of the heating process if needed
• Custom software to exactly match your technological process
• Each and every IR tunnel oven is a unique hand-made masterpiece
• Every customer has a warranty and technical support for the whole service life of our equipment

EIT-GP infrared tunnels provide uniform heating of the pipe’s surface by means of directional focused IR radiation of high power density. These tunnels have a special frame with a pneumatic drive and a device for opening and closing protective shutters to provide an inertia-free start-up for IR heating and quick (3-5 seconds) shutdown of IR heating in the event of an emergency or when the movement of material was stopped inside the tunnel.

The following table shows an estimated (meters per minute) production speed for PVC Hose (14 – 38,5 mm OD diameter) using our standard EUROLINIA EIT-GP tunnel consisting of 2 IR sections (see picture below):

Here you can see the production speed (meters per minute) for PE-Xa Pipes (17 – 81 mm OD diameter) with the same standard EUROLINIA EIT-GP tunnel consisting of 2 IR sections (see picture below):

A standard EIT-GP tunnel (EIT-GP-263х2-23.4/400-T8) includes:

• Horizontal heating chamber with a parabolic arrangement of emitters, comprised of heating half-cylinders moving on the horizontal frame
• Frame to accommodate the heating chamber
• Pneumatic actuator for reciprocating movement of heating half-cylinders and protective shutters
• Pyrometric temperature sensors
• Cooling system
• Control system
• Signal column
• Protective casing for moving half-cylinders
• PLC controller and software individually adopted for client’s application

In the operational heating mode, the half-cylinders are closed to form a parabolic heating chamber with different rows of ceramic infrared emitters (ICH) around the circumference. In a standby mode, the half-cylinders of the chambers are disengaged, and the area in front of the emitting surfaces (the area where the material is located) is protected from a radiant flux by protective curtains. Standby mode is also used for the initial installation of a pipe into the tunnel and for the removal of the pipe upon stopping the heating process.

Inertia-free heating start-up and stop system (IFSS-2) together with an energy-saving standby mode maintains the operating temperature of IR emitters and allows you to start and stop the production line with minimum losses of products and electricity.

The heating chamber of the EIT-GP tunnel has several IR power control zones around the circumference. Using individual automatic control over heating zones (zonal IR heaters) the tunnel can operate with a specific power density of the radiant flux evenly distributed along the surface of the heated material, on all sides.

Each heating zone in the IR tunnel includes a load-bearing reflective panel with ceramic infrared emitters (ICH) installed on it. The panel is made of polished high-alloy heat-resistant stainless steel, 12X18N10T (AISI 304, 321) type. Each heating zone also includes a thermal protection panel and a terminal box. The design and location of the reflectors ensure the thermal redistribution of the radiant energy reflected from the material, which contributes to a more uniform distribution of the specific radiation power along the pipe’s surface, and also protects the housing of the heating chamber from overheating. The thermal protection panel includes two layers of an efficient fibrous high-temperature heat insulation refractory. The welded frame of the heating chamber is made of high-alloy stainless steel, the external panels are made of AISI 430 type stainless steel. The terminal box contains heat-resistant ceramic terminal blocks to connect emitters, heat-resistant electrical wiring, thermocouple compensation cables to connect emitters' temperature sensors as well as emergency alarm wiring.

The time required for EIT-GP to reach the operating temperature is 15 minutes, time to cool emitters down to the temperature that permits maintenance and repair (45-50 °С) - not more than 30-40 minutes.

Maximum permissible temperature of the IR emitters (radiating surface) is 750 °C. Operating temperature of IR emitters is usually 300-650 °C, and the calculated effective wavelength range of infrared radiation (80% power) is 1.65-7.7 μm with a peak of 3.2 μm.

IR heating power is controlled by measuring the temperature of IR emitters’ radiating surface for every zonal electric heater. Signals from the thermal sensors of the emitters are delivered to the multi-channel high-speed temperature controller. This controller uses the power module to control the voltage supplied to the zonal electric heaters, maintaining the temperature setpoint for the emitters (IR heating power) in each zone.

An integrated control system protects the emitters from overheating, inner temperature sensors constantly monitor the emitters’ state and generate an "EMERGENCY" signal (visual, audial) indicating the relevant zone in case of failure in the three-phase circuit if one of the emitters fails (burns out).

Adjustment and control of each EIT-GP zone is carried out manually using the control panel or from a remote computer via the built-in RS-485 interface. The accuracy of the IR emitters' temperature regulation when working in a stable operating mode using the settings of PID-regulators is ±1.5 °C. EIT-GP operation is monitored visually by means of LED indicators for the corresponding heating zones on the control panel (mimic diagram), and from the control panel as well. Software allows you to monitor and change the temperatures of IR emitters online, load files with heating zones presets for various heating modes (diameter and speed of the pipe/material movement) from the existing database, calculate the current specific power of IR heating by zones along the surface of the pipe/material, determine the current percentage ratios of IR heating power by zones to accelerate and optimize the production process.

The pipe’s surface temperature is monitored at the exit from the IR tunnel at 4 points around the circumference using contactless pyrometric sensors. Depending on this information the temperature of the emitters is constantly adjusted to get the needed set temperature of the pipe.

Usually, every EIT-GP tunnel is a unique piece of equipment that is manufactured for a specific technological task of the customer. Acceptance tests are witnessed by the customer at the EUROLINIA manufacturing facility. Our company also provides technical support and consults clients on optimizing and improving their technological process throughout the whole service life of the IR tunnel.