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Engineer's Guide to Effective Heat Processing

Engineer's Guide to Effective Heat Processing

Product catalog summary

Process Description
Ovens and furnaces are crucial in industries for processes such as curing, drying, and heat treating. Ovens operate up to 1000°F, while furnaces exceed this temperature. Heat sources include fuel combustion, electricity, hot water, or steam, with heat transfer methods like natural and forced convection, and radiant heat.

Basic Oven Considerations
Choosing the right equipment involves understanding product requirements, such as material quantity, temperature tolerance, and processing type (batch or continuous). Batch ovens are versatile, while continuous ovens are often automated to reduce labor costs.

Heat-Up/Soak/Cool-Down Times
Key factors include the oven's heating capacity and the product's heat absorption rate. Soak time ensures the product stays at the desired temperature, controlled by programmable controllers. Cool-down is achieved by exhausting heated air, with options for controlled rates.

Temperature Uniformity
Consistent temperature across the oven is vital for product quality, requiring effective management of airflow and heat distribution.

Processes Involving Flammable Solvents
Special considerations include managing exhaust volumes and maintaining safe operating conditions.

Material Handling
Efficient systems like conveyorized ovens are essential for continuous operations, reducing manual handling and improving efficiency.

Types of Airflow
Airflow types, such as forced or natural convection, impact heat distribution and process efficiency.

Design Considerations for Hazardous Areas
Ovens in hazardous areas require specific design features for safety, including appropriate electrical requirements and process control systems.

Safety Issues
Safety is paramount, with considerations for insurance requirements and adherence to safety standards to prevent accidents.

Heat Exchanger Types
Air-to-water heat exchangers are suitable for lower temperatures, using a finned, water-cooled coil to regulate cooling rates.

Temperature Uniformity
Uniformity is crucial for consistent product quality, affected by factors like wall losses and air distribution. It is tested using a nine-point thermocouple survey.

Class A Ovens
Required for processing combustible materials, these ovens must have a forced exhaust, airflow proofing, a purge timer, and an explosion relief area.

Material Handling
Systems like trucks and conveyors are used to move products, considering product size, weight, and process time.

Airflow Patterns
Different patterns (horizontal, vertical, uniflow, reverse uniflow) are used based on load configuration to ensure uniform heat distribution.

Oven Loading Openings
The type of loading opening affects equipment choice, with options for manual or powered doors and drawers.

Heating/Cooling Systems
Gas heating is generally less expensive than electric, though electric provides better temperature uniformities. Cooling rates can be enhanced with exhaust fans or heat exchangers.

Atmosphere Type
Inert atmosphere ovens maintain low oxygen levels, while humidity can be controlled through steam injection or atomizers.

Design Considerations for Hazardous Areas
Ovens require spark-resistant fans, suitably rated motors, sealed wiring, and specific control enclosures to prevent ignition.

Overview
This document provides a guide on specifications, procedures, and considerations for process measurement and control, focusing on temperature sensors, controller performance, system dynamics, and oven construction.

Sensor Accuracy
Discusses temperature sensors, emphasizing thermocouples and their operating ranges, with factors affecting performance like location and wiring.

Process Control and Monitoring
Includes a table of thermocouple types and explains the importance of electrical power specifications for industrial ovens.

Controller Performance
Discusses digital temperature controllers with PID tuning parameters, highlighting input accuracy, tuning, and output accuracy.

System Dynamics
The physical construction of the oven impacts control system performance, with issues like non-uniform airflow affecting performance.

Oven Construction
Outlines floor types and construction standards, emphasizing materials like stainless steel for corrosion resistance.

Facility Considerations
Critical factors for oven installation include power supply, water drains, and access clearance, with advice on working with test facilities.

Insurance and Safety Requirements
Stresses the importance of meeting insurance requirements and addresses safety concerns related to oven design.

Catalog excerpts

Engineer's Guide to Effective Heat Processing-1

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:46.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Tahoma", sans-serif; } IUSTRIES ENGINEER'S GUIDE TO EFFECTIVE HEAT PROCESSING

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Engineer's Guide to Effective Heat Processing-3

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:31.00pt "Arial", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font3 { font:8.00pt "Tahoma", sans-serif; } About This guide discusses gnral issues related to the s驩lection of industrial equipment for heat processing. Since nearly all products manufactured today require heat application at some point in the process, this guide was created to provide a base knowledge of the complexity of issues related to selection of optimum equipment for any particular...

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Engineer's Guide to Effective Heat Processing-4

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font3 { font:8.00pt "Tahoma", sans-serif; } Batch-Type Ovens These ovens represent the largest category of ovens used to manufacture products Batch-type ovens can be classified as cabinet-style or truck-loaded type. The size can range from small bench top units to large industrial installations with thousands of cubic feet. Heat-Up/Soak/Cool-Down Times Heat-up, soak, and cool-down...

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Engineer's Guide to Effective Heat Processing-5

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:4.00pt "Impact", sans-serif; } .font1 { font:6.00pt "Impact", sans-serif; } .font2 { font:7.00pt "Impact", sans-serif; } .font3 { font:8.00pt "Impact", sans-serif; } .font4 { font:11.00pt "Impact", sans-serif; } .font5 { font:16.00pt "Impact", sans-serif; } .font6 { font:8.00pt "Lucida Sans Unicode", sans-serif; } .font7 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font8 { font:42.00pt "Microsoft Sans Serif", sans-serif; } .font9 { font:8.00pt "Tahoma", sans-serif; } .font10 { font:10.00pt "Tahoma", sans-serif;...

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Engineer's Guide to Effective Heat Processing-6

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:11.00pt "Impact", sans-serif; } .font1 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font2 { font:8.00pt "Tahoma", sans-serif; } With an inert atmosphre oven, however, cooling by means of exhausting oven air is not usually a viable method, as oxygen is introduced into the oven. Air-to-air or air-to-water heat exchangers are effective in removing heat from the oven in these applications. Air-To-Air Heat Exchangers These use a finned plate positioned between the oven air and a duct through which ambient air is...

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Engineer's Guide to Effective Heat Processing-7

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:8.00pt "Tahoma", sans-serif; } .font3 { font:25.00pt "Tahoma", sans-serif; } Processes Involving Flammable Solvents Material Handling When the material to be processed in an oven is combustible or contains flammable solvents, a special oven defined as "Class A" by the National Fire Protection Association (NFPA), Bulletin 86, is required. NFPA standards are used by OSHA and insurance underwriters to meet their requirements, as...

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Engineer's Guide to Effective Heat Processing-8

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:5.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font3 { font:8.00pt "Tahoma", sans-serif; } .font4 { font:6.00pt "Verdana", sans-serif; } Types of Airflow When selecting an airflow pattern, the most important considration is the load configuration. The main goal is to minimize obstructions to the airflow for more uniform heat distribution and to maximize the product surface area with which airflow will come into contact. Horizontal...

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Engineer's Guide to Effective Heat Processing-9

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:11.00pt "Impact", sans-serif; } .font1 { font:8.00pt "Tahoma", sans-serif; } .font2 { font:25.00pt "Tahoma", sans-serif; } ren Loading Openings Heating/Cooling The type of oven loading opening is quite important in order to get the right equipment to do the job. For example, standard reach-in front load models are well suited for products which can be loaded onto a shelf. These generally accommodate light weight or easy-to-handle parts. Walk-in front load units are used in truck load type applications or for large,...

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Engineer's Guide to Effective Heat Processing-10

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:7.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:8.00pt "Tahoma", sans-serif; } Atmosphre Type Thermal process ovens utilize diffrent atmosph詨res in order to satisfy certain processing criteria. For example, inert atmosphere ovens are generally utilized when a process requires a low oxygen concentration in the oven due to oxidation of the test parts at elevated temperatures. The inert gas is injected into a sealed chamber, pressurizing the oven and replacing the oxygen. With...

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Engineer's Guide to Effective Heat Processing-11

table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:7.00pt "Impact", sans-serif; } .font2 { font:11.00pt "Impact", sans-serif; } .font3 { font:9.00pt "Lucida Sans Unicode", sans-serif; } .font4 { font:8.00pt "Tahoma", sans-serif; } Electrical Requirements When specifying an industrial oven, it is essential to know what electrical power is available at the installation site. Electrical utilities vary widely throughout the U.S. and the world. You will need to know the voltage, phasing and the frequency, e.g., 480 volt, 3 phase,...

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