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Discharge Speed Control

The last option under System Settings is Discharge Speed Control. This contains all settings pertaining to the discharge speed and the settings associated with the different modes of discharge.

Manual Settings

On the bottom of the Discharge Speed Control page are the four discharge modes to toggle between. Each discharge mode has a separate set of settings.

Manual Settings Overview

Regardless of which discharge mode settings page is displayed, the operator can change the discharge mode from any one of them. However, it is important to understand that in order to change discharge modes, the operator must be in Manual mode first before changing to any of the other available modes. For instance, if the dryer is currently discharging in AccuDry mode and the operator wants to change to TruDry mode, the operator must first select Manual mode, and then select TruDry mode.

In addition to being able to select the mode of discharge from any of these pages, the Manual, TruDry and AccuDry Settings pages also all contain the same information for the following tiles: Disch Speed, Disch Speed Alarms, and Mid-Grain Temperature Alarms.

Manual Settings

When discharging in Manual mode, the operator controls the speed at which the grain discharges at. This adjustable value is under the Manual Settings tile, next to the Set Discharge Speed, input box.

Discharge Capacity

Each dryer model has a discharge capacity for every revolution of the metering rolls for profile dryers and sweep for tower dryers. These discharge capacities are used to calculate how much grain is being discharged from the dryer given a specific discharge speed. The chart below shows what these discharge capacities are in bushels per revolution and cubic meters per revolution.

Model(s)

Model(s)

Metering (RPM)

bu/hr

tonnes/hr

Setting Discharge Speed Operational Limits

From any of these discharge settings pages (Manual, TruDry, or AccuDry Settings pages), in the Disch Speed tile, the operator can set operational limits that pertain to the discharge speed. The two operational limits the operator can set are the max and min speeds the discharge can run at. With the operational limits in place, the user will not be able to enter a speed in the Set Discharge Speed box of the Manual Settings page that exceeds these limits.

The lowest allowable min limit that can be entered is 10%.

Setting Discharge Speed Alarm Limits

Again, from any of these discharge settings pages, under Disch Speed Alarms, the operator can set alarm limits that pertain to the discharge speed. There are two types limits: high limits and low limits. There also two types of alarms: warning alarms and critical alarms. If a warning alarm limit is exceeded, the control will trigger a warning message to be displayed on the HMI screens. If that particular reading continues further off course and exceeds the critical alarm limit, the dryer will shutdown and a critical alarm message will appear on the HMI screens.

High Speed Critical

If the Current Speed exceeds the value entered for the High Speed Critical value, the dryer will shut down. The input value for this High Speed Critical alarm must be equal to or greater than the value entered for the High Speed Warning value. To expand the allowable input range for the High Speed Critical value, the High Speed Warning value may first need to be adjusted.

High Speed Warning

If the Current Speed exceeds the value entered for the High Speed Warning value, the control will display a High Speed warning message. The input value for this High Speed Warning alarm must be equal to or less than the value entered for the High Speed Critical value. The lowest value allowed for this warning is equal to the Low Speed Warning value. To expand the allowable input range for the High Speed Warning value, the High Speed Critical and Low Speed Warning values may first need to be adjusted.

Current Speed

This value is the real time metering speed of the discharge system.

Low Speed Warning

If the Current Speed falls below the value entered for the Low Speed Warning, the control will display a Low Speed warning message. The input value for this Low Speed Warning alarm must be equal to or less than the value entered for the High Speed Warning value. The lowest value allowed for this warning is equal to the Low Speed Critical value. To expand the allowable input range for the Low Speed Warning value, the High Speed Warning and Low Speed Critical values may first need to be adjusted.

Low Speed Critical

If the Current Speed falls below the value entered for the Low Speed Critical, the dryer will shut down. The input value for this Low Speed Critical alarm must be equal to or lower than the value entered for the Low Speed Warning value. To expand the allowable input range for the Low Speed Critical value, the Low Speed Warning value may first need to be adjusted.

AccuDry Technology

The AccuDry mode of operation utilizes input signals from both the discharge moisture sensor and the infeed moisture sensor to control the dryer's discharge rate. When the AccuDry mode of operation is available, it will display it's corresponding toggle button under the TruDry button. Also, when on the AccuDry Settings page, an input will be made available which allows the operator to enter the target discharge moisture setpoint.

When running in AccuDry, similar to the guidelines that were provided for TruDry, the minimum and maximum discharge speed Operational Limits are important to the controller's operation. The AccuDry control algorithm will attempt to speed up and slow down the discharge to maintain the discharge moisture setpoint, and the amount of room that the controller has to work with is determined by the minimum and maximum speed setpoints. For example if the min/max speed setpoints are 1% - 100%, the range of speed output from the controller will be higher, which means the rate at which the speed changes will be higher. On the other hand, if the min/max setpoints are 30% - 75%, the controller can only operate within that band and only has a range of 45% to work with.

Similar to how the mid-grain temperature setpoint (used in TruDry) can be changed while in manual mode, so too can the discharge moisture setpoint (used in AccuDry) be changed while in manual mode. The only limitation is that the operator cannot change the discharge speed setpoint when running in TruDry or AccuDry.

In order to effectively use the AccuDry mode of operation, it is important to allow the dryer to get to a steady state operating condition for 2-3 hours upon initial installation (depending on the size of the machine and the incoming grain moisture) with a desirable and consistent discharge moisture output. Once this steady state condition has been met, the operator will confirm the discharge moisture setpoint that is desired and make any required changes. Also, be sure the minimum and maximum discharge speed Operational Limits are set to an accurate band.

The AccuDry system will remember grain moistures upon startup from the previous shutdown. For example, if the dryer was discharging 15.5% moisture the night prior, and start up with 15.4% the following morning, the system will allow quick entry into AccuDry mode.

If the discharge moisture is significantly different from the previous operations moisture, the system will not enable AccuDry until it has gathered sufficient information to run correctly and efficiently.

It is advised not to change the status of the burners while operating in AccuDry mode. Instead, change to manual discharge mode first, change the burners to off/on, then get back into AccuDry.

Using AccuDry Mode

AccuDry Status

While running in manual mode, AccuDry mode will not be available until the system is "Ready." The ready state is shown by the color of the AccuDry button, which is explained below.

AccuDry Not Ready (Grayed Out AccuDry Button)

By default, the dryer will not have enough information to jump right into AccuDry mode and the AccuDry button will appear grayed out. In order for AccuDry to be "Ready," the system must achieve the following before it will allow the dryer to enter AccuDry mode:

There must not be any alarms present;
The dryer must be in the "Running" state of operation, further explanation may be found below;
The Actual Discharge Rate must be within 5% of the Suggested Rate;
The Discharge Moisture must be within 2% of the Setpoint Moisture and;
The AccuDry system must have enough knowledge and runtime, to have a Predicted Discharge Moisture within 2% of the Actual Discharge Moisture.

Attempting to enter AccuDry Mode, whether ready or not, by pressing the AccuDry button from any of the discharge settings pages, will cause an AccuDry Status screen to appear as shown below.

This screen will appear slightly different depending on the state of the AccuDry model. The items displayed on this screen are the dryer running state, the not ready reason, the AccuDry predicted discharge moisture, the actual measured discharge moisture, the AccuDry suggested rate, the actual discharge rate, and whether or not the DM510 board is recording data (AccuDry Learning). This screen will provide information to better achieve AccuDry readiness, and will get the dryer into AccuDry much faster than guess work in Manual mode.

AccuDry Learning

On the AccuDry Status screen, the Learn mode will be illuminated when the dryer is operating (discharge is ON), and the moisture sensors have product being detected. This indicator states that the AccuDry system is "learning" from it's current operating inputs, and will stop "learning" and saving data when the discharge is turned OFF. Lastly is AccuDry mode, for when you are running in AccuDry mode.

AccuDry Dryer State

The dryer state field indicates the seven (7) stages of operating your dryer. The seven states are as follows:

AccuDry Not Ready Reason

The not ready field indicates the reason the dryer will not allow entry into AccuDry mode:

Suggested Rate

The suggested rate field indicates what the AccuDry system would run at that given moment if it were to take over controls of the VFD. It is important to note that this field updates regularly, and will become more and more accurate as the dryer learns for each individual grain type.

Actual Rate

The actual rate field indicates the real-time commanded speed from the PLC to the VFD.

AccuDry Ready

While running in manual when the AccuDry button text will change from gray to white, AccuDry reaches the "Ready" state. Pressing the AccuDry button will again cause the AccuDry status screen to appear. When AccuDry is selected from this screen, the button will flash "Enabling..." for a few seconds and will illuminate the AccuDry text in green lettering; the dryer is now in AccuDry mode.

Once AccuDry mode of operation has been selected, the ability to manually change the speed will be inhibited and the only parameter that can be adjusted will be the discharge moisture setpoint. While running in AccuDry, the speed will continuously increase or decrease to maintain the target discharge moisture setpoint. Do not continuously tweak the discharge moisture setpoint, let it try to control to the setpoint value that was previously established.

Typical Daily Routine

The following steps should be included in the daily routine when using the AccuDry system:

Before dryer start-up, check the outlet moisture sensor to ensure it is clean and free of debris. The sensor chute has no obstructions ahead of the sensor, and the flow-metering device is operating.
Start the dryer as has been done in the past from the dryer control panel. The Pinnacle 20|20 software will indicate the dryer is in "Manual" mode.
On the Dryer Overview screen, verify the discharge rate and discharge moisture setpoints. Modify them accordingly.
After the normal fan and burner startup procedure, as outlined in the Operations Manual, begin discharging.
AccuDry can be selected when the AccuDry button is illuminated white. Begin running in AccuDry and double-check the discharge moisture setpoint (now the only setpoint able to be changed) is correct.
AccuDry will now automatically adjust the dryer discharge rate to achieve the displayed product target moisture.
Periodically check the moisture sensors to ensure they are clean and there is good product flow. Metering may be turned off for roughly 60 seconds to clear out any fines or bees wings that may have accumulated in the sampling chute.
While operating the dryer, calibrate the moisture sensors as required.
When dryer discharge is turned off, AccuDry will automatically revert to "Manual” mode after 25 minutes.

How AccuDry Works

AccuDry technology utilizes the Dryer Moisture Systems Dryer Master DM510 system. The DM510 system uses specially designed in-line moisture and temperature sensors located at both the infeed and discharge of the dryer. These sensors provide continuous moisture and temperature readings to the PLC, which is shared with the DM510 logic board.

The DM510 board uses this information to build an operating model of your dryer. As infeed moistures and drying conditions change throughout the day; AccuDry continuously calculates and automatically adjusts to the optimum discharge rate for current conditions.

AccuDry has two important advantages. First, in automatic mode, it can continually watch the dryer. It does not have to help unload trucks, load trains, or do any other jobs around the elevator that a normal dryer operator does throughout the day. The dryer receives the user's full attention.

Second, it has the benefit of continuous moisture information from both the infeed and discharge of the dryer, giving it a complete picture of all the grain in the dryer, and the grain exiting the dryer.

With this information, AccuDry does not have to wait to react to changes in the outlet moisture. It is able to adjust the discharge rate as the incoming moisture changes. For example, as wetter grain comes into the dryer, AccuDry begins to slow down the discharge rate just as the wetter grain reaches the hot zone.

TruDry Settings

The TruDry Settings page is very similar to the Manual Settings page. The only difference, other than the component quick launches, is the "Set Discharge Speed" box displayed on the Manual Settings page has been replaced by mid-grain temperature boxes.

To understand the settings on the TruDry Settings page, it is best to first have a good understanding of how TruDry works.

TruDry Technology

TruDry is the name of a temperature based discharge mode of operation that automatically increases or decreases the discharge speed of the dryer. TruDry is not an automatic moisture control mode of operation and does not utilize the discharge moisture value, but instead controls the discharge rate by attempting to maintain an average mid-grain temperature setpoint. The mid-grain temperature is the temperature of the grain, measured approximately halfway down the heat zone of the dryer, and halfway into the grain column by an RTD (resistive temperature device). There are two RTD's, on opposite sides of the dryer, measuring the grain temperature. These two temperatures are used to calculate the average mid-grain temperature. The principal of operation is that as the grain entering the dryer increases in moisture, the mid-grain temperature will go down and when the grain entering the dryer decreases in moisture, the mid-grain temperature will go up. Therefore, what the controller will do is utilize a negative responding Proportional-Integral-Derivative (PID) control loop which will increase the discharge rate when the mid-grain temperature goes up and decrease the discharge rate when the mid-grain temperature goes down. This essentially means that as the grain's moisture goes up, the dryer will slow down and as the grain's moisture goes down, the dryer will speed up.

In order to effectively use the TruDry mode of operation, it is important to allow the dryer to get to a steady state operating condition for 2-3 hours (depending on the size of the machine and the incoming grain moisture) with a desirable and consistent discharge moisture output. Once this steady state condition has been met, the operator will want to set the mid-grain temperature setpoint to a value equal to the current actual mid-grain temperature. Note that although the dryer is running in manual, the operator will still be able to change the mid-grain temperature setpoint via the TruDry Settings page.

At this point, the dryer has been running for 2-3 hours and steady state has been reached, so the current reading for the actual mid-grain temperature should correspond to the desired grain moisture that is currently being discharged from the dryer. It is important to understand that TruDry is not controlling the dryer based on discharge moisture, but rather indirectly based on the average mid-grain temperature.

Another step to ensure a smooth and successful transition from manual mode to TruDry is to verify the minimum and maximum discharge speed Operational Limits are set to reasonable values. When running in TruDry mode this is especially important because the TruDry control algorithm will attempt to speed up and slow down to maintain the mid-grain temperature setpoint, and the amount of room that the controller has to work with is determined by the minimum and maximum speed setpoints. For example, if the min/max speed setpoints are 10% - 100%, the range of speed output from the controller will be higher, which means the rate at which the speed changes will be higher. On the other hand, if the min/max setpoints are 30% - 75%, the controller can only operate within that band and only has a range of 45% to work with. A table of suggested minimum and maximum values is shown below.

Recommended Min & Max Discharge Speed (Operational Limits)

Once the average mid-grain temperature setpoint has been set and the minimum and maximum speed range has been established, TruDry mode of operation can be selected by touching the TruDry button in the upper right corner of any of the discharge settings pages. Once TruDry mode of operation has been selected, the ability to manually change the speed will be inhibited and the only parameter that can be adjusted will be the mid-grain temperature setpoint.

While running in TruDry, the speed will continuously increase or decrease to maintain the target mid-grain temperature. Do not continuously tweak the mid-grain temperature, let it try to control to the setpoint value that you previously established. TruDry should be able to handle 3-5% swings in incoming moisture with reasonable discharge moisture variation if the dryer was properly brought up to steady state as previously explained. If after running for an extended period of time and it has been determined that the target mid-grain temperature is too high or too low, minor adjustments can be made, but should only be done periodically, not continuously. If the operator wants to meticulously control the dryer, then the dryer should be run in the manual mode of operation where the operator can directly control the dryer's discharge rate.

Discharge Speed Control

Manual Settings

Manual Settings Overview

Manual Settings

Discharge Capacity

Incremental Speed Tables

10% Discharge Speed

VFD Frequency = 6 Hz

20% Discharge Speed

VFD Frequency = 12 Hz

30% Discharge Speed

VFD Frequency = 18 Hz

40% Discharge Speed

VFD Frequency = 24 Hz

50% Discharge Speed

VFD Frequency = 30 Hz

60% Discharge Speed

VFD Frequency = 36 Hz

70% Discharge Speed

VFD Frequency = 42 Hz

80% Discharge Speed

VFD Frequency = 48 Hz

90% Discharge Speed

VFD Frequency = 54 Hz

100% Discharge Speed

VFD Frequency = 60 Hz

Discharge Capacity

20% Discharge Speed

VFD Frequency = 12 Hz

Incremental Speed Tables

10% Discharge Speed

VFD Frequency = 6 Hz

30% Discharge Speed

VFD Frequency = 18 Hz

60% Discharge Speed

VFD Frequency = 36 Hz

Manual Settings Overview

Manual Settings

90% Discharge Speed

VFD Frequency = 54 Hz

100% Discharge Speed

VFD Frequency = 60 Hz

50% Discharge Speed

VFD Frequency = 30 Hz

80% Discharge Speed

VFD Frequency = 48 Hz

40% Discharge Speed

VFD Frequency = 24 Hz

70% Discharge Speed

VFD Frequency = 42 Hz

Setting Discharge Speed Operational Limits

Setting Discharge Speed Alarm Limits

High Speed Critical

High Speed Warning

Current Speed

Low Speed Warning

Low Speed Critical

Setting Mid-Grain Temperature Alarm Limits

Alarm Band

Alarm Band Delay

AccuDry Technology

Speed Tables (Heat+Cool 10pt)

Speed Tables (Heat+Cool 5pt)

Speed Tables (All-Heat 10pt)

Speed Tables (All-Heat 5pt)

Using AccuDry Mode

AccuDry Status

AccuDry Not Ready (Grayed Out AccuDry Button)

AccuDry Learning

AccuDry Dryer State

AccuDry Not Ready Reason

Suggested Rate

Actual Rate

AccuDry Ready

Typical Daily Routine

How AccuDry Works

TruDry Settings

TruDry Technology

Recommended Min & Max Discharge Speed (Operational Limits)

AccuDry Settings