AREA III - Crop Processing Flashcards
A revolving, wheel-type, mechanical device used to move air for drying or aeration. For the purposes of this Standard, an AMD shall include the wheel or blade assembly, mounting structure and casing, but may or may not include a power source.
Air-moving device (AMD)
The purposeful movement of air at a low rate through a product to maintain or improve product quality. Air flow rates usually do not exceed 0.08 cubic meters per minute per cubic meter of product (0.1 cubic feet per minute per bushel of product) through a dry product and 0.80 cubic meters per minute per cubic meter of product (1cubic feet per minute per bushel of product) through a wet product.
Aeration
The temperature of the surrounding air.
Ambient temperature
The use of ”approved” or “approved-type” refers to listing by a recognized testing agency or laboratory.
Approved
In drying a harvested crop, the quantity of heat in air that can be utilized in evaporating water from the product.
Available Heat
A quantity of a harvested crop put into a bin or container on a repetitive basis specifically for treatment, such as drying.
Batch
The process of mixing two or more different products together, such as grains and
supplements, to obtain desired food ratios, or the process of mixing different quantities
of the same product with different moisture contents to obtain a final mass with a
uniform moisture content.
Blending
One bushel by volume equals to
1.25 cubic feet
The outer enclosure surrounding the entire heat exchanger and confining the air being heated.
Casing
Refers to a material or structure, which can burn. Combustible is a relative term.
Combustible Material
Transmission through or by means of a conductor, distinguished in the case of
heat from convection and radiation.
Conduction
Any component of a dryer, or dryer heat source, so designed to affect or limit any normal or abnormal condition of the drying operation.
Control
Transference of heat or electricity by moving masses of matter, as by currents in gasses and liquids caused by differences in density, or by electrically charged particles across a spark gap.
Convection
The time required to move a cooling zone entirely through the product mass.
Cooling Stage
That portion of the product mass in storage where the product temperature of
the crop is falling during aeration.
Cooling Zone
Volumetric measure of quantity of flow.
Cubic meters per minute (CFM)
A form of conditioning as opposed to simple drying in which a chemical change occurs, such as in tobacco, sweet potatoes, etc., to prepare the crop for storage or use.
Curing
Type of operation wherein application of maximum heat is periodic such as cycling between high fire and low fire, cycling between high fire and constant pilot; and cycling from high fire to “off”, then restarted to high fire by constant or intermittent ignition.
Cycling Burner
The rapid removal of moisture, usually to a very low level.
Dehydration
When drying with air, a depth which would contain enough product that, if all the theoretical heat available for drying could be used, it would all dry to equilibrium
in a period of time equal to the time required for the fully exposed product to dry halfway
to equilibrium.
Depth factor (Df)
A unit which provides the conditions for removing moisture from a product.
Dryer
Any dryer wherein the product to be dried is placed in the dryer, the complete drying or drying and cooling operation performed, and then removed for storage or further processing. Usually it is self-contained comprising a drying compartment, either horizontal or vertical, to contain the product being dried while heated air is forced or drawn through it from a central portion usually called a plenum chamber. Cooling is usually carried out in the same manner. Integral conveying equipment provides for loading and unloading the dryer. Also included are the AMD, burner, and control system. Batch dryers are usually portable, but may be stationary.
Dryer, batch
A batch dryer equipped to circulate or mix the product during the drying and cooling period.
Dryer, circulating
A type of continuous flow dryer wherein the product being dried moves in the same direction as drying air. Sometimes referred to as parallel flow.
Dryer, concurrent flow
Any dryer wherein the product to be dried is in continuous movement through the dryer and air movement is continuous, in contrast to batch operation.
Dryer, continuous-flow
A type of continuous-flow dryer wherein the product being dried moves in one direction and the drying air moves in the opposite direction.
Dryer, counter-flow
A type of dryer wherein the flow of air is transverse to the direction of the flow of the product being dried.
Dryer, cross-flow
Type of dryer in which the products of combustion come into direct contact with the product being dried.
Dryer, direct-fired
A dryer where the product is in suspension, or is moved through the dryer by the drying and/ or the cooling air.
Dryer, fluidized or spouted bed
Type of dryer in which the products of combustion do not come in contact with the products being dried.
Dryer, indirect-fired
A dryer in which the drying bin or compartment is also used to store the product after it is dried.
Dryer, in storage
Any dryer manufactured as a package unit consisting of the drying and cooling chamber, necessary heat or radiation source, all AMD’s and duct work, along
with the necessary controls and product handling equipment. These dryers may be either
fixed or portable.
Dryer, self- contained
A type of dryer wherein the product being dried is conveyed through a tunnel-like chamber. It may be continuous or batch-type.
Dryer, tunnel
The removal of moisture from a product, usually to some predetermined moisture content.
Drying
The air being passed through the product which is being dried.
Drying air
The temperature of the air entering the product being dried.
Drying air temperature
The divisional layer between dried and undried products in drying systems.
Drying front
The maximum elapsed time that may be used to complete the drying of any portion of the product without undesirable change in quality.
Drying time maximum permissible
The band or layer of product in which most of the drying is occurring at any instant.
Drying zone
Act or process by which an electric conductor becomes electrified when near a charged body.
Electrical induction
The moisture content of a product when it is in equilibrium with the surrounding atmosphere.
Equilibrium moisture content
The relative humidity of air surrounding the product in equilibrium with given moisture content. The air and product are at the same temperature.
Equilibrium relative humidity
A control designed so that a malfunction of any of its components will stop the operation of the device or equipment controlled by it.
Fail-safe control
The fuel train, mounted on the grain dryer structure and connected to the gas burner, includes all piping components of fuel flow control and safety shut-off valves.
Fuel train
A device used to transfer heat from one fluid stream to another without intermixing.
Heat exchanger
Use of forced ventilation with the addition of heat for removing moisture.
Heating-air drying
Basic heated-air-producing unit including AMD, burner system, and electrical system. It is usually coupled to drying structure by means of a flexible duct. It may have transport chassis and wheels for portability.
Heated-air unit
A type of fitting designed to prevent galvanic current flow when used between two dissimilar metals.
Insulating fitting-
A measure of quantity of heat. One joule will raise the temperature of one gram of water one degree Celsius. (One BTU will raise the temperature of one pound of water one degree Fahrenheit.)
Joule (BTU)
The pressure of the fuel in the supply line to the dryer.
Line pressure
A mixture of gaseous petroleum products normally stored and transported as a liquid under pressure. The principal constituents are propane and butane.
LP-gas
Automatically governing the rate of fuel flow by a control which is temperature-sensitive in order to maintain a constant temperature at the location of the sensing device.
Modulate (as applied to crop drying in reference to regulation of fuel in continuous
flow)
For products, expressed as percentage, by weight, of water in the product divided by dry matter.
Moisture content (dry basis)
For agricultural producers, usually expressed as percentage, by weight, of water in the product, wet basis.
Moisture content (wet basis)
A gaseous hydrocarbon, odorless and flammable, found in its natural state in particular geologic formation as a product of decomposition of organic matter. The composition is chiefly of the methane series with varying amounts of other components
such as carbon dioxide, hydrogen, and helium often being present.
Natural gas
The opening through which gas is admitted to the burner.
Orifice
A measure of pressure or stress. Assumed to be gage pressure unless followed by the term “absolute”.
Pascal (psi – pounds per square inch or inches of water column)
The pilot remains lit during the time power is supplied to the burner.
Pilot- continuous
The pilot is lit during the time combustion is being established. When combustion is established the pilot is de-energized.
Pilot- interruptible
The pilot is manually lit and remains lit until manually shut off.
Pilot-standing
An air chamber maintained under pressure (positive or negative) usually connected to one or more distributing ducts in a drying or aeration system. The term is also used to designate the air chamber under the perforated floor in a grain bin and the pressure chamber between grain columns in some types of batch or continuous dryers.
Plenum
A mechanical device which reduces the fluid (liquid or gas) pressure to a relatively constant delivery pressure while the inlet pressure may vary and while the volume of gas may also vary.
Pressure regulator
Method of air movement in which air is forced through the product with the air duct or ducts at a pressure above atmospheric pressure. It is called a pushing or forcing system of air movement.
Pressure system
As applied to crop dryers, the term refers to clearing or purging the plenum chamber or duct of any volatile gases prior to ignition of the burner. It is usually accomplished by a device which insures that the fan must operate for a certain period of time before ignition will be permitted.
Pre- ventilation
The process by which energy is emitted from molecules and atoms owing to the internal changes. Also the combined process of emission, transmission, and absorption of radiant energy.
Radiation
As applied to crop dryers, the term refers to the return of the portion of the exhaust air to the air intake of the dryer, or to the return of under dried grain to the dryer or container from which it was removed.
Recirculation
A measure of the moisture content of air expressed as a percentage. It is the ratio of the weight of water vapor in a given volume of air at a given temperature to the maximum quantity of water vapor which the same volume of air could hold at the same temperature.
Relative humidity
A measure of air pressure usually expressed in pascals [inches of water column (WC)].
Static pressure
Condition when the operation or process reaches equilibrium.
Steady state
Method of air movement in which the air is moved through the product with the air duct or ducts at a pressure lower than atmospheric. It is also called an exhaust system of air movement.
Suction system
Continuous monitoring to react automatically to flame failure so as to shut off gas flow to the unit.
Supervision
Any heat added to that already present in the atmosphere to obtain a limited temperature rise, usually less than 11°C (20°F), to accomplish drying within the maximum permissible drying time to prevent spoilage.
Supplemental heat
As applied to crop drying, the term refers to the difference between ambient temperature and the temperature and the temperature of the drying air resulting from the addition of heat by the dryer burner.
Temperature rise
Equilization of moisture or temperature throughout the product. Bringing a product to a desired moisture content or temperature for processing.
Tempering
The elapsed time from the start of the drying process to the instant the drying front arrives at any point or place in the product.
Time of drying
Time required to dry fully exposed products halfway to equilibrium.
Time of one-half response
The process of moving a product through the air within a bin or storage structure, or from one bin or storage structure to another.
Turning
A check valve which permits flow of fluid in either direction but which limits excessive flow in one direction. If the designated flow is exceeded, the valve automatically closes.
Valve, excess-flow
A valve designated as a safety device to open, and remain open, to discharge a fluid whenever the fluid pressure reaches the start-to-discharge setting of the valve. When the fluid pressure drops below this setting, the relief valve automatically closes.
Valve, pressure relief
A manually operated valve specially designed to accomplish rapid shutoff to fuel flow to dryer.
Valve, quick-acting
A valve which is opened or closed by a solenoid (electromagnet). In the normally closed type, for example, the valve is opened by the solenoid but closed by a return spring and held closed by the fluid pressure upstream from the valve.
Valve, solenoid
Commonly taken to mean saturated vapor pressure which is the vapor pressure of a vapor in contact with its liquid form. An example is the pressure in an LPgas storage tank. The term is also used for the pressure of the vaporized fuel being fed to the burner orifice.
Vapor pressure (fuel)
In an LP-gas system, the vaporizer is a heat exchanger wherein heat is supplied to change the liquid fuel to vapor, ready for combustion. The vaporizer may be integral with the burner so that part of the heat of combustion is used for vaporization.
Vaporizer
An integral vaporizer-burner unit, dependent upon the heat generated by the burner as the source of heat to vaporize the liquid fuel.
Vaporizer-burner
The rate of air flow determined by dividing the quantity of air flow in cfm by the cross-sectional area.
Apparent velocity in meters per minute (feet per minute)
The rate of air travel through product void space. It is determined by dividing the apparent velocity by the product void space expressed as a decimal. The average velocity is always greater than the apparent velocity.
Average velocity
The in-product travel time of air from entrance to any point, usually in seconds.
Traverse time
Air movement through space.
Ventilation front
The space between particles in a bulk of stored crop, usually expressed as percent of total volume.
Void space
So constructed or protected that exposure to the weather will not interfere with safe operation.
Weatherproof
