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Unique Advantages of Microwave Heat Processing
Product Overview
MICROWAVE REMOVAL PROCESS TO MITIGATE LEAD-BASED PAINT HAZARD
This Microwave is used for paint-removal of windows and doors
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The removal of lead-based paint is known to create hazardous dust and waste. Historically, the Department of Defense (DoD) used lead-based paint to cover steel structures and buildings totalling approximately four billion square feet. In order to comply with Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) requirements, DoD needs a cost-effective technology to remove, characterize, and dispose of sources of lead, such as paint.
Current removal methods for hazardous paint that contains lead, chromium, or cadmium all rely on chemical stripping, abrasive blasting, vacuum assisted power tools, or high-intensity and excessively noisy xenon lamps (Flashjet). Methylene chloride based chemical strippers are suspected carcinogens, and OSHA has stringent requirements for worker protection. Methylene chloride also is classified as a Hazardous Air Pollutant (HAP) and is regulated by the EPA. Alternate environmentally acceptable chemical strippers are slow and create a large quantity of hazardous waste from the rinse water.
Abrasive blasting may require as much as five pounds of abrasive per square foot. This large quantity of waste is usually hazardous because of the presence of lead in the paint chips. The cost of abrasive blasting is increased further by the containment structures, which generally are required for environmental and worker protection. Additionally, abrasive blasting cannot be used inside of buildings because of the hazardous lead dust that is generated.
As a result of the shortcomings of the existing methods, there is a critical need for a more affordable, environmentally acceptable technology to remove deteriorating lead-based paint from DoD facilities.
Recent
research supported by SERDP at the U.S. Army Construction Engineering Research
Laboratories (USACERL) indicates that the microwave assisted process is a viable
solution and is a cost-effective alternative to currently used technologies,
such as chemical stripping, for removal of lead-based paint from the interior
of buildings. Microwaves have the unique ability to heat a coated surface rapidly
and selectively. The microwave technique was patented by USACERL (U.S. Patent
No. 5,268,548, A. Kumar). In the microwave assisted removal process, microwave
coupling compounds (i.e., susceptors) are applied as a waterborne slurry or
as a polymer binder paste to the painted surface. Susceptor
materials, such as graphite or iron oxide, can reach temperatures up to 1000°C
in less than
a minute when exposed to microwaves (800 watts). Activated polyaniline, a susceptor,
has the advantage of being a self-regulating material (i.e., loses conductivity
as it is heated), thus reducing the fire hazard. The paint debonds from the
substrate by heat from the microwaves and is removed easily by scraping. Chemical
stabilizing compounds, such as calcium silicate and phosphate, are applied to
the susceptor prior to heating with microwaves. Following removal, the chemical
stabilizers immobilize lead from the paint when mixed with water. The resulting
waste is classified as non-hazardous, as can be verified by the EPA’s Toxicity
Characterization Leaching Procedure (TCLP).
To date, two design approaches for the microwave paint removal system have been fabricated and used in the laboratory to remove lead-based paint. The 1000-watt system developed by a Pennsylvania State University incubator technology firm, HVS Technologies, located in State College, Pennsylvania, was designed to heat a relatively small area rapidly and uniformly. An alternate design for a microwave system was developed by USACERL in order to minimize arcing and potential damage to the wood substrate, as shown in the figure below. In the USACERL system, the microwave power is reduced and is applied over a larger area, thereby reducing the energy intensity on the surface. A standard 1000-watt microwave generator was modified to limit the power output to 300 watts, and the power was applied to the surface using a 20 dB gain horn fitted with safety switches and a flexible shield.
A
proof-of-principle field test of microwave paint stripping was performed on
an Army building near Lexington, Kentucky, in December 1997. Both the HVS and
USACERL microwave systems were used successfully to remove lead-based paint
from an interior wood door and sill. The lead levels on the wood were reduced
dramatically on the areas stripped, with removal rates similar to those achieved
in laboratory experiments. Laboratory studies continue to try to optimize the
efficacy of the microwave susceptors and chemical stabilizers to render the
paint waste non-hazardous. When this technology is commercialised successfully,
it will substantially reduce (by approximately 50 percent) the costs associated
with lead-based paint abatement during renovation through reduced hazardous
waste disposal costs and fugitive dust emissions. This technology has the potential
for solving a significant hazardous waste problem during the Base Realignment
and Closure (BRAC) demolition of wooden buildings containing lead-based paint.
Additionally, application of this technology to DoD facilities containing lead-based
paint, including family housing, will promote healthier facilities and improved
quality of life for military personnel and their families. Finally, since more
than 57 million homes in the United States contain lead-based paint, this technology
will have widespread application beyond DoD. Microwave assisted paint stripping
also is being considered for removal of surface coatings from aircraft composite
materials where methylene chloride based chemical strippers would damage the
composite or a Flashjet system cannot reach the area.
This Microwave is used for Drying and Pasteurisation
TEMPERING FROZEN FOOD WITH MICROWAVES
For many production processes incoming raw material is frozen in thick blocks and stored at -10o to +15oF until ready to use. The first operation on this material usually is to dice, slice or separate individual sections into smaller pieces. This mechanical operation requires that the blocks be "tempered" from their solid frozen state to a point just below freezing (20oF to 30oF) at which point cutting or separation can be done without damage to the product. The temperature to which a product must be tempered depends upon the type of cutting, slicing, chopping, etc., required; and also upon product variables such as the combinations of water, salts, proteins, fats, etc.
Tempering should be done without overheating any part of the product. Yet, conventional heating requires that the outside surfaces be subjected to substantially higher-than-product temperatures for some time in order to conduct sufficient heat to the centre of the block. Thus it produces large temperature gradients, with both under tempering and over tempering in the same block. How is microwave heating different?
Conventional heating is done with externally applied heat (water, air) that must creep slowly into the frozen blocks. Microwaves heat simultaneously throughout each block; the inside is heated at the same time as the outside.
In conventional tempering, cartons of frozen food in solid blocks weighing up to 100 pounds are raised in temperature to just below freezing. Most plants dunk the blocks into warm water. Others use hot air. Many use floor tempering alone, without any heat aid, which may take 48 to 72 hours. Microwave tempering is applied on a moving belt to food still in cartons, and generally takes less than five minutes.
More examples of products:
tire Reduction System
DRYING: Microwaves selectively heat with little direct heating of most solids. Drying is uniform throughout the product; pre-existing moisture gradients are actually evened out. Drying is at relatively low temperatures; no part of the product need be hotter than the vaporizing temperature.
DRYING & PREVENTING MILDEW OF BAMBOO PRODUCTS: It is used for drying, killing bugs and preventing mildew of bamboo, wood, paper board, medicine, tea and various kinds of foodstuff. Microwave energy radiation with excellent penetrability has much more advantages, including homogeneously heating substance inside and outside, short processing time (only several minutes), good controllable with no heat inertia, high electro thermal efficiency and saving energy. It has good result in sterilizing and preventing mildew, and is able to keep original color and lustre of substance. The equipment is easily operated and suitable for continuously production in a clear and comfortable environment.
DRYING AND STERILIZING EQUIPMENT: The equipment is used for drying, sterilizing and keeping fresh of bean-milk powder, sesame paste, pollen, ginseng, tablet and pill of traditional Chinese medicine, mushroom, garlic slices, and agricultural products etc. Microwave energy with excellent penetrability is homogeneously distributed in the equipment, it has high electro thermal efficiency of 70 percent, fast processing speed and good resistance to light load. It is able to heart rapidly, and provide good sterilizing effect in lower temperature in result of heat and no-heat biological effect, and keep much more nutrition. Processing program can be conveniently regulated in a sanitary environment.
FINISH
DRYING: When most of the water has been removed by conventional heating
methods, microwaves remove the last few percent of moisture from the interior
of the product... quickly, efficiently, and without overheating the already
dried material. More information:
For
more information on drying see: http://www.technology.novem.org
(English)
Voor meer informatie over drogen zie: http://www.technology.novem.nl
(Dutch)
FREEZING: Freeze-drying and keeping fresh of various kinds of food and material quickly-frozen under minus 18ºC, including vegetables, foodstuffs, aquatic products, chemical and pharmaceutical products, such as: onions and garlic, tomato, carrots, green leaf vegetables, dried fresh flower, strawberry, seafood, ginseng and pilose antler etc. It has come outstanding superiorities, including homogeneous energy distribution and simultaneously freeze-drying (freeze-dehydrating) of substance inside and outside, which are not limited by geometry and thickness of substance. Comparing with traditional processing, the period of microwave processing is reduced to 1/10-1/3, original lustre; taste and nutrition of foodstuff is well kept and there is good re-hydration.
BAKING: Internal heating quickly achieves desired final temperature throughout the product. Microwaves can be combined with external heating by air or infrared to obtain crust.
CONCENTRATING: Permits concentration of heat-sensitive solutions and slurries at relatively low temperatures. Also applicable to highly corrosive or viscous solutions.
COOKING: Microwaves cook relatively large pieces without high temperature gradients between surface and interior.
CURING: Uniform, rapid heating throughout the product is ideal for bulk polymerisation reactions which are heat-initiated. Also effective for glue-line curing of laminates without direct heating of the laminates themselves.
ENZYME INACTIVATION (BLANCHING): Rapid, uniform heating of the inactivation temperature can control and terminate enzymatic reactions.
HEATING: Almost any heat transfer problem can benefit from the use of microwaves because of their ability to heat in depth without high temperature.
PASTEURISING: Microwaves heat a product rapidly and uniformly to pasteurising temperature without the overheating associated with external, high temperature heating methods.
DRYING AND STERILIZING OF DRIED BEEF: It is used for cooking, drying and sterilizing of meat food such as dried beef and preserved pork. It is also applied to dry and sterilize various kinds of food and material, including agricultural by-products in form of grain, root and stem tuber, stuff of traditional Chinese medicine and chemical raw material etc. The equipment has excellent microwave penetrability and microwave energy is homogeneously distributed in it, so it is able to heat and dry beef homogeneously and quickly. It has much more advantages, including high electro thermal efficiency, short processing time, lower sterilizing temperature, excellent expanding effect, so that loss of nutrition and vitamin can be reduced, and original flavour and lustre can be kept. The equipment can be operated simply and continuously in a sanitary environment.
PRECOOKING: Microwaves are ideal for precooking "heat and serve" items because there is no overcooking of the surface and cooking losses are negligible. When the consumer reheats the food by conventional methods, just the right amount of "outside-in" cooking is done to give the desired texture and appearance of home-cooked items. The equipment is also used for cooking and drying of dried meat floss, smoked fish, bean product, dried sliced meat, sterilizing and keeping fresh of various kinds of food in bag, including pot-stewed meat, preserved meat and pickles etc, and expanding and drying of leisure food such as apple slice, sesame and almonds etc.
NO/LESS OIL INSTANT NOODLES: It is used for paste-forming, dehydration and drying of instant noodles and rice flour, and for saving oil and drying of fried noodles. The equipment has advantages of rapidly and evenly heating, saving energy and being controlled easily. Comparing with the traditional fried noodles. It has high gluten, good springiness, favour taste, and clear soup. There is no problem of oil oxidizing and reciting. It is a kind of low fat, low sugar and low salt food. The 5-6percent of oil can be saved with microwave processing.
RIPENING LIQUOR OR VINEGAR AND STERILIZING BEVERAGE: The equipment is used for ripening liquor or vinegar and sterilizing milk and soft beverage. The equipment is able to relieve cruel taste of raw liquor treated by microwave for 1-2 minutes so that the liquor has smooth, sweet and tasty flavour. Its effect is equivalent to traditional ripening process for six monthes. There are much more merits, including short period of capital turnover, les land area occupied, simple production technology, high automation and convenient operation.
PUFFING & FOAMING: Ultra-rapid internal heating by microwaves causes puffing or foaming when the rate of heat transfer is made greater than the rate of vapour transfer out of the product interior. Microwaves are ideal for producing puffed snack foods.
ROASTING OF DRIED FRUITS: It is used for roasting, expanding and drying of various kinds of dried fruit such as watermelon seeds, peanuts, walnuts, almonds and Chinese chestnuts etc. It is also applied to peel off peanuts and Chinese chestnuts. It has much more superiorities, which are homogeneous and fast heating, high electro thermal efficiency, excellent expanding effect, good lower temperature sterilizing, less loss of nutrition, original flavour and lustre well-kept. There are other merits, including simple production technology and sanitary operating environment.
TAKING OFF FISHY OF BEANS IN DRY PROCESS: The equipment is used for taking off fishy of beans flour, heating, cooking and drying of poultry and pork, and roasting and expanding of fruit and vegetable such as ginkgoes and peanuts etc. Comparing with traditional technology, the equipment needs less investment and its production technology is more simply, and production period is greatly shortened. There are higher use rate of veins and less loss of nutrition like water-dissolved protein, the total production cost is greatly reduced.
SOLVENT REMOVAL: Many solvents other than water are efficiently vaporised by microwaves, permitting solvent removal at relatively lower temperatures.
MOISTURE LEVELING: Because the microwaves heating effect is roughly proportional to moisture content, microwaves are ideal for equalizing the moisture in a product which leaves a process in a non-uniform condition.
THAWING-TEMPERING: Controlled, rapid thawing of bulk items is possible due to the deep penetration of microwaves into frozen materials.