Mobile Grain Dryer

Overview

The Mobile Grain Dryer is a trailer-mounted continuous-flow dryer that lowers the moisture content of freshly harvested grain so it can be stored safely. Corn, wheat, soybeans, and other crops often come off the field above the moisture level at which they keep without spoiling. Grain held too wet heats, molds, and loses grade. A farm that owns a dryer can harvest earlier and at higher field moisture, then bring the crop down to a storage-safe level on its own schedule rather than waiting for the field to dry or paying an elevator. Because the whole machine sits on a Trailer Chassis, one dryer can serve several grain sites or move between farms.

The dryer works by forcing a large volume of heated air through a thin bed of grain. Wet grain enters at the top, flows slowly down through perforated columns while hot air passes across it, and leaves at the bottom at the target moisture. The rate at which grain is pulled out of the bottom sets how long each kernel stays in the heat, which in turn sets how many points of moisture are removed.

Grain column and plenum

The grain is held in the Grain Column & Plenum, a pair of Drying Column channels each bounded by two sheets of Perforated Screen. The perforations are small enough to retain grain but open enough to pass air freely. Between and behind the columns sits the Plenum Chamber, a sealed box that the fan pressurizes. Air leaves the plenum, crosses the 12 inch grain bed, and exhausts to atmosphere carrying the evaporated moisture with it. A Plenum Divider separates an upper heated drying zone from a lower cooling zone, so grain is heated, then cooled by ambient air before it is discharged. Internal Grain Baffle vanes spread the grain evenly across the column width, and Sight Glass Port ports let the operator confirm steady flow.

Fan and airflow

The drying air is moved by the Fan System. Its Centrifugal Fan Wheel is a backward-curved steel impeller that delivers roughly 22,000 cfm against the static pressure of a packed grain bed. The impeller rides on a Fan Shaft carried by two Ball Bearing pillow blocks, and is belted to the Fan Motor, a 25 hp totally enclosed induction motor built around a Stator Assembly and a Rotor Assembly. Power passes through matched Drive Belt V-belts from the motor sheave to the Fan Pulley. The Fan Housing (Scroll) scroll collects the impeller discharge and feeds it into the plenum inlet, while Vibration Isolator mounts keep fan vibration out of the frame. Airflow volume is the main lever on drying speed, since each cubic foot of air can carry away only so much water before it saturates.

Burner and heat

Heat comes from the Burner System, which fires directly into the air stream ahead of the plenum. The Burner Ring is a drilled stainless ring that spreads the flame evenly across the airflow, rated up to 28 million BTU/hr at full fire. Fuel reaches it through the Gas Train: a Gas Regulator drops LP tank or pipeline pressure to a stable working pressure, a Gas Strainer protects the valves, and two Gas Solenoid Valve safety shutoffs open only when the controller proves safe conditions. A Modulating Gas Valve then trims the fire rate to hold the plenum at setpoint. At startup the Spark Igniter lights the gas and the Flame Rod Sensor confirms a stable flame, dropping the system into lockout if the flame is lost. An Air Mixer (Venturi) venturi blends combustion air into the gas for clean burning. Higher plenum temperature dries faster but risks stress-cracking or scorching the kernels, so the operator balances temperature against grain quality.

Grain handling

Grain enters and leaves through augers. The Load Auger feeds wet grain from a wagon into the Receiving Hopper, where a Hopper Trash Grate screens out cobs and stones. A Fill Auger lifts grain into the columns and a Leveling Auger spreads it evenly, while a High-Level Paddle Switch stops filling when the columns are full. Each auger is turned by a worm-geared Auger Gearmotor built on a Helical Gear Pair and a Gearbox Housing. Once dried, grain leaves through the Unload Auger to a storage bin. The flighting and tubes are shared across the augers using the same Auger Flighting and Auger Tube parts.

Metering and moisture control

The key to even drying is controlled discharge. The Discharge Metering System uses fluted Metering Roll sets at the column base to pull grain out at a precise rate. The Metering Drive turns those rolls through a Variable-Frequency Drive, so the operator can speed up discharge for slightly wet grain or slow it down to remove more moisture. The Moisture & Temperature Control System closes the loop. A Grain Moisture Sensor reads outlet grain moisture in real time, a Plenum Thermocouple watches plenum air temperature, and a Grain Thermocouple guards against overheating the grain. The Dryer Controller uses these readings to trim the modulating gas valve and the metering speed, and shows status on the HMI Panel. Sensor wiring runs through the Wiring Harness using shared Wire Bundle and Connector parts, and field devices are switched by Relay outputs from the I/O Module.

Trailer and transport

The whole dryer is built on the Trailer Chassis so it can move under tow. A welded Trailer Frame about 28 ft long carries the columns, fan, and burner. A Transport Axle rides on Transport Wheel assemblies, and a Tow Hitch with Safety Chain links the dryer to the tow vehicle. A Road Lights Kit kit provides legal lighting, and four Leveling Jack screw jacks level and stabilize the unit once it reaches its operating spot.