Why is it essential to measure moisture in stored crops, such. Why is it important to measure multi point and in-sitú in the storage silo?

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2 In-sitú measurement of moisture in stored commodities Technology & Application Peer Hansen - Biochemist Crop-Protector KS - Denmark

3 Why is it essential to measure moisture in stored crops, such as rice, corn, wheat, beans etc.? Why is it important to measure multi point and in-sitú in the storage silo? Because the target is to preserve the harvested crop in its optimum condition, for as long as possible and minimize any risk of damaging the grain and avoid unnecessary shrinkage due to loss of moisture

4 More specifically the APPLICATION could be defined as a tool to accomplish: GRAIN SAFETY ISSUES: Determine the moisture content of the grain Utilize that information to confirm that the stored commodity is in a safe condition And if not begin to undertake corrective action as soon as a problem seems to develop PROFIT OPTIMISATION: Continuously confirm the good quality of the grain Utilize the information for AERATION PURPOSES, so that the commodity is kept at the reference moisture concentration (ex. wheat 15% moisture). One lost percentage of moisture is One lost percentage of the value of the commodity

5 A brief overview of some of the issues related to safe storage of crops, especially in regards to the GRAIN MOISTURE issues. Insects, fungus and all other biologic activity in a grain storage silo are dependent on moisture to procreate and grow. Monitoring the moisture would be the strongest tool to get truly in control. GRAIN WEEVIL ATTACK FUNGUS ATTACK

6 APPLICATION

7 What is the problem with moisture? The initial condition after harvesting and possibly drying, will have put the crop into a condition but never into the optimum condition. All of the following temperatures and moistures will have to be considered: TEMPERATURE and MOISTURE of the stored grain TEMPERATURE and MOISTURE of the air in the silo TEMPERATURE and MOISTURE of the outside air All of these parameters are given; they are all the result of the process the grain went through, and the climatic condition under which it is being stored. Once the grain has been has been loaded into the storage bin the only operational parameter you have - from that moment on - is aeration. And only if the bin is equipped with aeration fans. That s what makes grain storage difficult and critical and also why the That s what makes grain storage difficult and critical, and also why the moisture parameter in the dynamic storage process is so important to monitor and possibly to control.

8 Theoretical example of fractions of (Temperature ; Moisture) of grain in a storage bin In each silo there will be areas with different grain moisture concentrations. When aeration is in progresses moisture will be moved around in the silo. IF you have a detailed on-line knowledge of the grain and air moistures in the bin THEN you can use AERATION to possibly even out these differences, and obtain a uniform grain moisture throughout the bin.

9 Safe Storage INSECTS is a major risk above deg C. FUNGUS is a major risk at grain moisture contents above 15 18% (depending on the temperature) SAFE STORAGE can only be obtained for a longer period of time if temperature and moisture is brought to the safe condition (white area) Therefore measures of TEMPERATURE and MOISTURE of the grain are the key surveillance parameters I N S E C T S SAFE CONDITION INSECTS and FUNGUS FUNGUS

10 In temperate climates: Cool the grain to prevent storage problems

11 In tropical climates the situation is more complex and challenging: More difficult to secure safe storage SLAM procedures (Sanitation, Loading, Aeration and Monitoring) are even more essential Monitoring actions is more essential Obtainable storage time may be shorter Higher needs for corrective actions: CHILLING and FUMIGATION Especially when storing crops over longer periods of time at higher temperatures (above 18 deg. C) the grain moisture is the ultimate monitoring tool (rather than temperature), because it is the key to secure that excess moisture is not turned into biologic activity (fungus and insects).

12 Moisture migration is a major problem in all silos Moisture and heat is constantly transferred inside the silo Warmer air always moves upward, and colder air downwards, thereby creating air flows, and thereby moisture migration When warmer air streams are moving into colder grain condensation may eventually occur The specific moisture migration is dependant on a large number of factors especially: Climatic condition (heat transfer from outside) Type of storage structure (steel or concrete, flat storage etc.) Size of the structure Direct sunlight exposure Use of aeration fans and roof vent fans

13 4,000 ton bin of corn during summer storage in Indiana, USA Non-aerated on July When the grain temperature t is substantially different from the outside temperature the temperature isotherms are close. This creates different equilibrium temperatures, and will therefore also create some moisture migration. Since the temperature differences can not be avoided it is important to know the actual moisture concentrations. With intelligent use of aeration fans and head space fans the moisture migration can be controlled to some degree. Ref.:Prof. Dr. Dirk E. Maier, Ph.D., P.E.; Kansas State University

14 SUMMARIZING the application aspects of an in-sitú multi point grain moisture system The system must be able to provide the following information: Measure the grain moisture everywhere in the silo During aeration the moisture of the ventilation air should be measured The silo head space moisture concentration must be monitored at all times This information should ideally be utilized to accomplish the following tasks: Monitor grain moisture throughout the storage silo Confirm safe storage condition Give immediate information if excess moisture is present Constitute the basis for an aeration system that aerates just enough to remove excess moisture, and at the same time not over aerate and create shrinkage

15 TECHNOLOGY Having evaluated the applicational needs for the system, we can now define the technological requirements for a monitoring system for grain moisture

16 The optimum principle of operation The sensor system must be based on measuring the relative humidity in the inter granular air space During non aeration conditions (=ZERO AIRFLOW) this would be measuring the Equilibrium Moisture Concentration (EMC), and During aeration the system should measure the moisture of the air flowing trough the silo, and give information of the concentration Two different datasets t will be obtained during storage; information from both is be essential for operational purposes (aeration) In addition humility of the outside air, and the silo head space air y, p would also be critical information for an optimum aeration decision

17 EQUILIBRIUM MOISTURE CONCENTRATION Equilibrium is the state where there is a balance between the moisture inside the kernels of the grain, and the humidity in the inter granular air between the kernels. It takes some time for this equilibrium to settle; then there will be a direct relation between this relative humidity and the grain moisture. This may in theory be a little more simple than it is in practice, but it is no more difficult than measuring water activity. it Example with wheat to the right.

18 TEMPERATURE AND HUMIDITY To understand how the moisture evaporates from the grain, or condensates at which temperatures inside the silo, and calculating how the energy balance is maintained is difficult! The so-called H-X diagram will give you an overview of how the thermo dynamics inside the bin works Scientists have tried to develop models based on these calculations, however the number of parameters involved are too big, and consistency between theory and observations have never been demonstrated to match. Such models have only proven fruitful for theoretical purposes, not for practical silo management! Measuring the moisture multi-point and in-sitú makes such models irrelevant since it provide the actual status at all times in the entire silo H-X Diagram

19 Requirements for the design of the GRAIN- SURVEYOR moisture probe Sensors must be reliable and durable The multi sensor system should be easy to install and use In the design of the probes it was therefore emphasized that the probes was similar to temperature sensor probes

20 The moisture sensor The moisture sensor is basically measuring the relative humidity in the air Since the humidity of the air is in equilibrium with the moisture in the grain kernels (water activity), the relative humidity can be calculated into grain moisture (Not if the aeration fans are on!) There are many practical problems associated with the design of the sensor: Since you need many, the price should preferably be low The sensor should not drift, especially have no long term drift Because of the vast amounts of dust in a grain silo the sensor must be insensitive to dust, or dust must be filtered away The system must be integrated with a temperature sensor to obtain the relative humidity For us this turned out to be a challenge and although initial results were For us this turned out to be a challenge, and although initial results were promising, it took five years to launch the first commercial system We ended up with a our own custom development

21 Design of the moisture sensor probe The moisture sensor system is designed in a similar way to the temperature sensing system: Sensor lines are suspended inside the silo, and for every 2 meter there is a TEMPERTURE and MOISTURE sensor All those sensor points will generate an overview of the moisture migration inside the silo Basically the sensor measures the relative humidity of the inter granular air thereby measuring the EQUILIBRIUM MOISTURE With some calibration procedures the EQUILIBRIUM MOISTURE can then be used to calculate the exact moisture content of the grain The sensor line Temperature sensor point Moisture sensor point 2 meter distance to next sensors Temperature sensor point Moisture sensor point

22 The GRAIN-SURVEYOR sensor system in the silo Head space Sensor for: Air Temperature T(Air) Air Humidity rh(air) n 4 3 Sensor for ambient temperature and relative humidity Sensor 2 for: Grain Temperature T(g) Grain Humidity rh(g) Sensor 2 for: Air Temperature T(Air) Air Humidity rh(air) Sensor 1 for: Grain Temperature T(g) Grain Humidity rh(g) Sensor 1 for: Air Temperature T(Air) Air Humidity rh(air)

23 The GRAIN-SURVEYOR probe Photo to be inserted The SL

24 The GRAIN-SURVEYOR probe Photo to be inserted Picture from a silo

25 Presentation of the measurement data With a a number of silos, and a number of sensor lines in each silo, the amount of data being collected is rather big It is essential to have a good overview of the data, so that t it is logical l and easy for the user to see, and to apply it When using the data for automatic aeration control it is even more complex to design an easy to understand screen overview On the next slide is show an example from the GRAIN-NURSER software that has been developed to utilize the information from moisture probes for aeration purposes

26 Operator interface

27 Optimized profit by optimizing grain moisture concentration to reference value Effect of moisture content on a bushel of marketed grain Moisture Dry Moisture Dry Discount Matter Weight Content Water Matter Price/bu. (2%/pt.bu.) Price Grain (lb.) (%) (lbs.) (lbs.) ($) ($) (-/lb) Corn Corn 56 * Corn Wheat Wheat 60 * Wheat Soybeans Soybeans 60 * Soybeans Test Weight Grade Minimum Adjustments are not Considered. * Market Standard Moisture Reference: Grain Moisture Content, Effects and Management AE-905 (Revised), March 1995; Dr. Kenneth J. Hellevang, PE

28 Possible future technologies I believe that advanced aeration control will become a very important issue in the future, and since the measurement of moisture is so important I expect that new technologies will emerge. Here are some of the technologies we have looked at: Radio wave transmission in the bin Multipoint measurement based on NIR with a multiplexer and optical fiber technology

29 TECHNOLOGY and APPLICATION Thank you for listening!