Ensure Product Quality & Minimize Energy Costs with In-Line Moisture Measurement System

Continuous in-line (also referred to as on-line) moisture monitoring systems are being used by manufacturers of all types of goods to verify that the product being packaged is at the optimal moisture level to ensure the best quality of the finished products for their consumers. Additional reasons for using these types of sensors include automating the drying or moistening processes of materials for consistent product quality & energy cost savings and receiving real-time moisture data without having to make numerous laboratory samples.

Some of the main criteria that a company should consider when choosing an in-line system include:

Ability to easily incorporate the sensor into their process and receive continuous, real-time measurements instead of having to take multiple laboratory samples.
Capability to measure the moisture to the product's core instead of just the surface to increase the consistency of the measurements.
Ability to receive fast and precise measurements with accuracy.
Durability of the sensor and the sensing surface to withstand a particular product's characteristics (ex. abrasive).
Capability to have the sensor output communicate with an existing control system to receive alarms and control the processes or the option of a local operator interface / controller.

For more details on Monitor's HumiCore inline moisture system, please visit:

http://www.monitortech.com/moisture-measure.shtml

Typical Applications:

In-line moisture sensors can be used for most powders and bulk solids processes that incorporate conveyor belts, screw conveyors, pipes, chutes etc. (See image below)

Common target materials include:
Cement, Sand, Aggregates, Coal, Feed and Grain, Cereal, Malt, Flour, Sugar, Spices, Potato products, Dried Food / Products, Wood Shavings, Chemicals / Fertilizers, Powder, Pigments, Plastic granules and more.

Installation Options:

HumiCore moisture sensor in a screw conveyor application

Application Example:

A silica sand company located in the southern US was looking for a method to validate the proper moisture content of their sand prior to it being size classified and packaged for their consumers. It was particularly critical that the moisture measurement be performed in-line (on-line) within the process, thereby achieving real-time results without the delay associated with sampling systems.

The company felt that an in-line (on-line) moisture measurement sensor would help them achieve their goals. The moisture monitoring of the sand would assist them in two important ways:

Prevent sand that is too moist from getting to the particle size screen and blocking it up. A blocked condition can slow down or even stop valuable processing time and possibly cause equipment damage.
Ensure sand being packaged was at the proper moisture content to achieve the best quality of the finished products for their customers.

Their process consists of taking the raw sand from a receiving hopper and conveying the material to the dryer. After the drying is complete, the sand is belt conveyed to a bucket elevator system that brings the sand to the particle size screen. The sand is then sorted by size and sent to bins that dispense the sand for packaging.

The company did some research and decided to use the HumiCore^TMPRO in-line (on-line) moisture measurement system. Before the sensor was installed, the company and sensor manufacturer collaborated to determine the optimal location to place the sensor. The moisture sensor was installed immediately following the dryer using a sled to glide across the surface of the sand. At this point, the sand is being conveyed to the size-sorting screen. If the sensor detects a higher level of moisture in the material than desired, an alarm is sent to the control room. Then a chute can divert the sand back to the dryer before it is re-sent through to the sorting screen. Using an optional DIN-Rail transmitter, the company was able to have the output signal of the moisture sensor integrate easily with their other control functions. The HumiCore system has been successfully working as anticipated and the company is very pleased with the results.

HumiCore moisture sensor mounted on a sled in a silica sand conveyor application

HumiCore PRO sensor and transmitter

Technology Review:

Continuous in-line moisture measurement sensors used for process monitoring of product moisture in solids and emulsions applications are usually based off of a few common technologies. These technologies include near infrared (NIR), high frequency field and microwave. The HumiCore™ Pro moisture sensor, chosen by the example company, uses a circuitry principle that is centered around an electrical high frequency field. This is based on technology that has been developed and proven to be successful over several years.

There are several benefits of high frequency field technology including:

Ability to measure moisture within the material core. In many applications, it is critical to measure not just the surface moisture, but rather the inherent (average) moisture through the core of the material. Drying processes extract moisture from material by exposing the material’s external surfaces with heat. Naturally the surfaces closest to the heat source will see a greater moisture reduction. The high frequency field technology is able to penetrate the material nearly 8” (200mm) so the attained moisture measurement is actually measuring the material core, a truer representation of the actual moisture content. This is a critical difference to near infrared (NIR) technology which is only able to measure the surface moisture of the material.
Ability to measure moisture regardless of particle size, particle shape, particle surface characteristic or color. The high frequency field technology is not affected by these material characteristics.

About Monitor Technologies' Humi Core^TMIn-Line Continuous Moisture Measurement System

- Measures moisture inside the material core to ensure product quality

- High frequency field technology for fast, reliable measurements with typical accuracies of 0.1% to 0.3%

- Compact design for easy calibration and installation in conveyor belts, screw conveyors, drag conveyors, etc.

- Ideal for most powders / bulk solids

- Automates moisture control to minimize energy costs & maximize profits

- Continuous, in-line monitoring eliminates need for frequent laboratory samples

- Available with a local interface controller (ULTRA Series) or with a DIN-Rail transmitter that allows for easy integration into an existing control system (PRO Series)