Moisture measurement and control is a crucial aspect in every manufacturing plant that should be implemented.
By Adrian Fordham

Moisture is important in any manufacturing process, but when it comes to waste alternatives, excess moisture can ruin products. And what is worse than a wasted effort? Economical losses and decreased productivity. With continuous online moisture measurement, waste-to-energy plants will find huge money savings. From savings in transportation due to weight of excess moisture, to savings in water usage for dust suppression and clean-up, plants also reduce the amount of wear and tear on equipment due to the dust and ash build up and prevent blockages on the conveyor resulting in shutting down the boiler.

Moisture measurement and control can:
• Reduce dryer usage and energy costs
• Properly control of the infeed and dryer exit
• Give better quality of final product
• Give consistency of your final product
• 100 percent product inspection
• Dust and fire elimination
• Reduce purchase costs from water weight

moisture2
Waste moisture control. Images courtesy of Moist Tech.

Near Infrared Technology and Refuse Derived Fuel
Although the discovery of Near-Infrared (NIR) is attributed to William Herschel in the late 19th century, the first industrial application was not until the 1950s. NIR spectroscopy and imaging are fast and nondestructive analytical techniques that provide chemical and physical information of virtually any matrix. NIR can tell us things about a product in a similar way to visible light. When light hits a product, it will interact in various ways. Transmitted light will pass through the product while backscattered light will reflect from the product. Light will also be absorbed by the product. Absorption is the key to the most effective moisture measurement analysis technique.

Produced from recovered waste, RDF is a high-yield source of energy for producing heat and electricity, as well as being a waste disposal alternative. It is made up of dry, non-hazardous waste which can be recovered through incineration on municipal sites (household waste incinerators) or on high-capacity industrial plants.

RDF is produced from domestic and business waste, which includes biodegradable material as well as plastics. Non-combustible materials such as glass and metals are removed and the residual material is then shredded. Refuse derived fuel is used to generate energy at recovery facilities, many of them in Europe where they produce electricity and hot water for communal heating systems.

Controlling the Ash Residue
In waste-to-energy facilities, controlling the ash residue is a critical concern of plant operators. After combustion, the ash residue that is left is sprayed with water to reduce dust and odors, which is then transported to landfills/moonfuls. However, too much or too little moisture can create several problems for waste-to-energy plants.

Managing the ash residue is an important step for many reasons at incineration facilities around the world. From minimizing the possibility of ash dust inhalation and ingestion of employees, to preventing ash being absorbed into the environment, as well as lowering transportation costs due to weight. With an NIR moisture sensor, operators will be able to instantly and continuously measure ash moisture and control these problems.

To prevent airborne dust and controlling weight of the ash, it is recommended that a sensor is installed after combustion and moisture spray. From past installations and depending on the matrix of the ash, the optimum moisture range is 15 to 18 percent with a target of 15 percent for control of dust and weight of the ash. The moisture content lowest point is 12 to 14 percent before the ash becomes airborne and above 25 percent moisture the ash turns into mud that contains surface moisture (liquid), making it very heavy and expensive to haul away.

SRF preparation is usually carried out directly on waste sorting and recovery sites, for which it represents a complementary activity, which, in turn, creates more jobs. The SRF preparation lines are deployed to treat the waste in a five-step process: crushing, drying, sorting, second crushing, pelletizing. Typical accuracy is about ±0.2 percent for ash moisture applications with a moisture range of 0 to 30 percent moisture. Once installed, operators can continuously monitor the process and control the moisture content either manually or automatically.

With continuous online moisture measurement, waste-to-energy plants will find huge money savings. There are savings in transportation due to weight of excess moisture, to savings in water usage for dust suppression and clean-up. Plants also reduce the amount of wear and tear on equipment due to the dust and ash build up and prevent blockages on the conveyor, resulting in shutting down the boiler.

The Benefits of a Moisture Measurement System
Managing the ash residue is important step for many reasons at incineration facilities around the world. From minimizing the possibility of ash dust inhalation and ingestion by employees, to preventing ash being absorbed into the environment, as well as lowering transportation costs due to weight. With a moisture measurement system, operators will be able to instantly and continuously measure ash moisture and control these problems.

As mentioned previously, manufacturers can see multiple benefits with a moisture measurement and control system, including:
• Reducing dryer usage and energy costs
• Proper control of the infeed and dryer exit
• Better quality of final product
• Consistency of your final product
• 100 percent product inspection
• Dust and fire elimination
• Reduce purchase costs from water weight

Immediate ROI is seen with the installation of a moisture measurement system as the plant controllers will instantaneously notice the reduced waste, energy usage and overall increase in product quality.

When looking at moisture measurement systems, be sure to evaluate features that will be most beneficial to your operation. The best ones to look for are:
• One-time calibration: Pre-calibrating the sensor to be ready to read your specific application.
• Multiple applications can be read: The moisture measurement system can remember up to 50 different applications and measurements so you can easily switch back and forth to allow the machine to acknowledge a new product is being read.
• Immediate results: The sensor produces hundreds of readings per second to allow the user to have immediate access to the product moisture content, allowing for increased or decreased dryer control.
• All equipment included: Everything needed to operate the sensor is included and the software can be installed on an unlimited number of devices, allowing for better access throughout the process.
• State-of-the-art technology: Continually researched and updated technology allows for the most accurate results in the moisture measurement industry.
• 30-day performance guarantee: See results or send it back—plain and simple.
• Installation: Ideal for installations on chain and screw conveyors.

Typical accuracy with an NIR sensor is about ±0.2 percent for ash moisture applications with a moisture range of 0 to 30 percent moisture. The sensor should be installed several inches above the conveyor belt. Once installed, operators can continuously monitor the process and control the moisture content either manually or automatically. For monitoring and control, the sensor(s) can be directly connected to the users PLC or any laptop. In addition, look for instrumentation that can monitor the system even with small gaps in product flow and is unaffected by ambient light without impacting the accuracy.

A Crucial Aspect
Moisture is important in any manufacturing process, but when it comes to hog fuel, waste fiber, wood chips, pellets, saw dust, shavings and forest waste, excess moisture can ruin products. And what is worse than a wasted effort? Economical losses and decreased productivity. Renewable energy moisture control benefits include less waste, reduced energy costs, better product quality, decreased amount of downtime and 100 percent product inspection. Look for a moisture measurement control system that is calibrated to your application at the factory and has a non-drift optical design allowing operational personnel to confidently make immediate process adjustments based on real-time measurements, is insensitive to materials variations such as particle size, material height and color and can store up to 50 different calibrations to easily allow the user to adjust between products. Moisture measurement and control is a crucial aspect in every manufacturing plant that should be implemented. | WA

Adrian Fordham has been President of MoistTech Corp. (Sarasota, FL) since 2013, seeing the company’s growth to more than 50,000 installations worldwide. He can be reached at (941) 727-1800 or e-mail info@moisttech.com.

Sponsor