CYLINDRICAL HEATING SYSTEMS (CHS)
IMS Cylindrical Heating Systems provide a unique solution which is best utilized for the continuous thermal processing of heat and shear sensitive, high viscosity, and multiphase materials that demand precise temperature control. 

Each CHS heats a single or multiphase product as it is pumped through a microwave-transparent heating tube located in the center of the cylindrical heating chamber or applicator.  The volumetric heating that results from the agitation of the polar molecules in the product means that no hot tube sidewalls are required for heat transfer. 

As a result, an IMS CHS allows processors to improve their product cost effectiveness and quality, reduce equipment footprint or floor space, and in some cases create new or enhanced pumpable products.  This is due to the cool wall surface temperature of the microwave heating tube, combined with the minimal residence time and uniform ultra-rapid heating of the product.  This combination is achieved without the fouling, maintenance and replacement part costs associated with conventional hot surface heat exchangers.

Cylindrical Heating Systems are composed of the following major components:

Product Heating Tube – Allows material to be pumped through the IMS heater where the product absorbs microwave energy that is available in a well defined cylindrical geometric region. This "microwave inert" tube is typically made out of food grade Teflon and/or ceramic material.  It is specially selected and designed to insure it does not heat up by absorbing electromagnetic energy while meeting the required operating temperature & pressure requirements of the process system.

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 that surrounds the product heating tube using unique designs and geometries within a focusing structure.  Available in aluminum or 304 stainless steel, it is designed to allow the target material to pass through a uniform microwave field, and efficiently absorb the available microwave energy. The applicator is the essence of Industrial Microwave Systems’ competitive advantage, and its design, construction and/or process application is patented.

Watch an animation of a CHS

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 CHS, and facilitates automation programming as well as in-process adjustments of variables such as generator power output, power reflections 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 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 CHS trouble-shooting if necessary.

Safety Features – Sensors constantly monitor the entire CHS 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.

Every IMS CHS incorporates a unique “choking” section at the entry and exit to the applicator that reduces microwave leakage to well below industry accepted levels for safety. 

Operator safety shrouds are available for most industrial applications.

The industrial system shown below is undergoing in-house trials before customer shipment.

Design Codes – Each CHS is designed to conform with design codes specified by various US government and industry regulatory authorities.  These include the Occupational Safety and Health Administration (OSHA), the National Electric Code (NEC), the National Electrical Manufacturers Association (NEMA), the Food and Drug Administration (FDA), 3-A Sanitary Standards, Incorporated (3-A), the National Sanitation Foundation (NSF) and the US Department of Agriculture (USDA).

PROCESS DESIGN SPECIFICATIONS

IMS designs and supplies Cylindrical Heating Systems in both 915 and 2450 MHz frequencies. Calculation of the required power output, optimum magnetron frequency, applicator design and selection of product heating tube are determined by:

• A brief description of the type, physical and chemical properties of the pumpable fluid.
• Maximum particle size if the fluid is not homogeneous.
• The mass per hour of material being pumped and thermally processed, expressed in kilograms or pounds.
• The thermal properties of the material, namely specific gravity, specific heat and average viscosity.
• The dielectric or microwave absorption properties of the material.
• The required product entry and exit temperatures.
• The maximum design/ test temperatures and pressures 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.

STANDARDIZED CHS DESIGNS

915 MHz commercial scale Cylindrical Heating Systems are available as 100 kW standardized modules for the chemical, biomaterial, and food and beverage processing industries.  They are offered 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 two applicators.  This allows the product to be exposed to a lower power density which can improve the overall product quality of pumpable heat sensitive fluids (with or without particulates) during the heating process.

Full details of the weights, dimensions and utility requirements for a standard IMS 100 kW 915 MHz heating module are available from this brochure .

2450 MHz commercial scale Cylindrical Heating Systems are recommended for low volume, high value applications such as the rapid heating and sterilization of biopharmaceutical solutions, development of new food ingredients, and preparation of formulations by flavor houses and pharmaceutical companies.  Single magnetrons are available with a power output of up to 30 kW, but IMS has currently standardized on heating systems with 2, 3 or 6 kW maximum outputs.  These laboratory scale units are ideal for stand-alone bench top applications or for incorporation into existing conventional heating systems.

A photograph of a 3 kW CHS being tested prior to shipment is shown below.

Full process specifications and details of the weights, dimensions and utility requirements for standard 2450 MHz CHS are available from this data sheet .

NON-STANDARDIZED CHS DESIGNS

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

 

PRODUCT DEVELOPMENT

In-House

In order to properly model the performance of the Cylindrical heater when used with a specific pumpable fluid, the dielectric properties of that fluid must be known.  In cases where customers do not have this information, the IMS Development Center, located in Morrisville, NC, will use in-house dielectric test equipment to measure the product's dielectric constant and loss tangent over a frequency range that includes the standard 915 MHz and 2450 MHz industrial heating frequencies. 

IMS uses a commercial test fixture and software from Agilent, along with a vector network analyzer to perform the measurements.  The measurements are typically repeated several times over a temperature range of interest for the particular product. 

The example graphs below are for a fruit-based product, and show the variation over temperature and the difference in dielectric properties for 915 MHz and 2450 MHz.

Third Party

Customer trial facilities are available at the Department of Food Science at Purdue University. 

The pilot plant facility at Purdue has a 100 kW IMS cylindrical heating system similar to the standard commercial system offered by IMS.  It can provide a broad selection of equipment for material storage, handling and preparation, mixing and blending, pre-heating, pumping, cooling, and either aseptic or non-aseptic packaging.  In addition, it can offer customers full sensory and analytical services for their products under strict confidentiality. 

For more information about the Purdue facility, please see https://ag.purdue.edu/foodsci/Pages/pilot_plant.aspx or watch a video of the IMS CHS.  Contact Us to set up a trial. 

CHS Rental Unit

IMS offers a portable CHS, complete with a 5 kW 915 MHz microwave generator, cylindrical heater, variable speed progressive cavity pump, hold tube, valves, instrumentation and control system for customer trials.  An optional tube-in-tube cooler is also available.  This rental system can be shipped to an R & D or production facility allowing customers the convenience of in-house microwave heating tests without involving third parties.  All rental contracts include full technical support from IMS to assist customers with equipment set up, commissioning, operation and training.

Full process specifications and details of the weights, dimensions and utility requirements for this rental unit are available from this data sheet