Product Information

PLANAR HEATING SYSTEMS (PHS)

IMS Planar Heating and Drying Systems can offer a better alternative to conventional re-circulated hot air dryers due to the best-in-class uniformity, efficiency and thermal processing they demonstrate in many industrial processes.

Each PHS continuously heats and/or dries a thin sheet or bed of product as it is horizontally conveyed through a rectangular heating chamber or applicator on a specially selected microwave inert plastic modular belt.  Depending on the application and material, some products are can be dried vertically without a belt.  The volumetric heating that results from the agitation of the polar molecules in the product, results in rapid, uniform heating and/or drying of the product in a fraction of the time required by a conventional dryer.  

As a result, an IMS PHS allows processors to improve their product cost effectiveness and quality, increase production volumes, reduce equipment footprint or floor space, and improve the manufacturing environment since the IMS PHS generates no dangerous NOx or SOx emissions.  These benefits may be achieved without the high installation costs, downtime, high maintenance costs and pollution often associated with conventional dryers.

 

 



 

Major Components of a Planar Heating System
Elements of a Planar System
 

 

Planar Heating Systems are composed of the following major components:

Microwave Generator – Generates the microwave energy at a frequency of either 915 or 2450 MHz. The generator and its ancillary components include a magnetron, electromagnet, power supply unit, circulator (to protect the magnetron) and water load.  The generator components are typically housed in a NEMA 12 floor mounted enclosure.  Except for air-cooled 2 kW generators, a flow of water is required to cool the magnetron, circulator and water load.

Applicator – Contains and distributes the microwave energy around the product.  It may not include exhaust fans if minimal product drying or dehydration is required.  Available in aluminum as standard, it is designed to allow the target material to pass through it uniformly on a moving conveyor belt with variable speed control.  The product can then efficiently absorb the available microwave energy to achieve the desired final temperature or moisture content.

The applicator is the essence of Industrial Microwave Systems’ competitive advantage, and its design, construction and/or process application is patented .  IMS has developed three applicator designs to meet and optimize most customers' heating and drying requirements:

The Ridged Waveguide Applicator is designed as a series of modules containing specially designed waveguides arranged in a serpentine fashion.  The orientation of the electric field is parallel to the direction of the product as it is conveyed through the applicator, resulting in high absorption of microwave energy by the product.

 

 
Elements of a Planar System
 

The Wide Applicator is an oversized waveguide structure with variable attenuation capabilities.  The orientation of the electric field is perpendicular to the material as it is conveyed through the applicator, reducing the rate of power absorption across the product.

 
Elements of a Planar System
 

In the Linear Applicator, product moves through a single waveguide on a conveyor belt, and the power is directed along the length of the conveyor belt.

 
Elements of a Planar System
 

Wave Guides – Microwave energy is conveyed from the generator to the applicator by interconnecting wave guides.  These allow the generator to be located in a separate area away from the applicator at a distance of up to 30 meters (100 feet) before any significant loss of power output is experienced.  Wave guides may incorporate manual tuning stubs that allow an operator to optimize  microwave energy absorption of a product, dependent on its dielectric properties and temperature.

Control System – Monitors and controls the performance of the PHS, and facilitates automation programming as well as in-process adjustments of variables such as generator power output, reflected power and product exit temperature.  The control system is usually comprised of a Programmable Logic Controller (PLC), a touch screen control panel, and devices for data acquisition, power monitoring, and temperature or moisture monitoring.  It also incorporates process alarm features that identify, record, and assist the resolution of process control issues. 

The control system is typically supplied in a water resistant NEMA 4 stainless steel wall mounted enclosure.  Various input and output signals can be used to communicate and integrate with total plant automation control systems, greatly assisting with monitoring and recording overall production throughputs, temperatures, pressures, etc.

Whenever a customer provides a dedicated land based phone line, IMS service technicians can remotely access the control system through an Ethernet modem.  This greatly assists with PHS trouble-shooting if necessary.

Safety Features – Sensors constantly monitor the entire PHS for the leakage of microwave energy, and communicate with the control system for automatic shut down in the unlikely event that excessive electro-magnetic radiation or leakage is detected.

IMS planar heating systems incorporate a “choke” section at the entry and exit of each section or applicator.  This reduces microwave leakage to well below industry accepted levels for safety.  A typical choking section is shown below.

 

 

 
Elements of a Planar System
 

PROCESS DESIGN SPECIFICATIONS

IMS designs and supplies Planar Heating and Drying Systems in both 915 and 2450 MHz frequencies. Calculation of the required power output, optimum magnetron frequency, applicator design, selection of conveyor belt material and maximum speed are determined by:

  • A brief description of the type, physical and chemical properties of the material to be heated and/or dried.
  • Maximum thickness of the material bed depth or particle size, as appropriate.
  • The mass per hour of material being thermally processed, expressed in kilograms or pounds.
  • The average specific heat of the material.
  • The dielectric or microwave absorption properties of the material.
  • The required product entry and exit temperatures and/or moisture.
  • The maximum design/test temperature required.
  • Available space, namely footprint and height.

To request a quotation for your application, please Contact Us with the information detailed above.  The brief description is particularly important as it may enable IMS to determine thermal and dielectric properties without the need for a product sample.

Due to the variety of IMS PHS applicators, specific details of the weights, dimensions and utility requirements are confirmed after determining the best design that meets your inquiry.

STANDARDIZED PHS DESIGNS

915 MHz commercial scale Planar Heating and Drying Systems are available as 100 kW standardized modules for the textile, pet food, non-woven materials, foam, coal, biomass and agricultural processing industries.  They are recommended as single units or as multiple units connected either in parallel, series, or a combination of both.  In some cases it is possible to split the power from a single 100 kW generator into several input ports located along or across the applicators.  This allows the conveyed material to be exposed to a lower power density which can improve the overall quality of heat sensitive products during the heating and/or drying process.

2450 MHz commercial scale systems are also available, depending on the application. The picture below shows a 3 kW Planar Heating and Drying System prior to shipment.

 

 

 
Elements of a Planar System
 

NON-STANDARDIZED PHS DESIGNS

IMS has the capability to develop non-standard applicator designs for customized process applications.  Contact Us for additional information.

PRODUCT DEVELOPMENT

In-House

The microwave performance of IMS planar systems is governed by the microwave absorption characteristics of the the material to be heated and/or dried.

The IMS Development Center, located in Morrisville, NC, often characterizes the material by placing a sample in its test system, and then measuring the response of the system for different moisture levels in the material.  The results provide absorption parameters for IMS drying models to calculate the overall system efficiency.

In addition, IMS can conduct in-house trials by offering a wide selection of applicator types and sizes.  Contact Us for further details.