Wind power systems for heat production, storage and supply of granaries: Existing technology, facilities and equipment for grain storage - introduction to the project

Satisfaction of internal needs of the state in food grain, seed grain and fodder grain, as well as growth of its export could not be achieved without the measures concerning grain storage, which include receiving, storage, and shipment of grain. Technical base of grain storage infrastructure are a complex of enterprises, production facilities, equipment and machines that are parts of these enterprises and provide conditions of grain storage. A key element of the infrastructure is a grain warehouse - a legal entity that has granary and certificate for compliance of the grain storage and food processing.

Technical regulator of the grain storage warehouse, developed to fulfill the law of Ukraine «About the grain and grain market in Ukraine» and Decree of the Cabinet of Ministers of Ukraine from 11.04.2003 N 519 «About the provision of certification of grain warehouses» gives definitions of terms and sets the basic requirements to the grain storage technologies.

The subjects of grain storage are: cereal grain storage warehouses, agriculture manufacturers that store it in their own or rented granaries, and other entities involved in the process of grain storage.

Grain warehouse for providing services of grain storage and food processing must have his granary, necessary equipment and qualified personnel appropriate for the provision of services for grain storage. Grain warehouse provides the next services: quantitative and qualitative storage of grain crops, using progressive technologies, efficient equipment with low cost of grain storage; processing of cereals to standards of quality that meet the criteria of grain storage; providing labour safety and protection of the environment.

Production buildings and structures should be located on the territory of grain warehouse taking into account the next factors: prevailing wind direction on the territory of the warehouse; placement of the electrical power heat only boiler station in separate buildings; accommodation of solid fossil fuel warehouse along the railroad tracks; presence of underground reservoirs for water supply with the volume of 250…500 m3.

Thermal power station of the grain warehouse includes systems for hot water and steam supply. Hot water can be also received from the centralized heating system. In the case of an autonomous heat power supply the heat only boiler station has water-heating boilers providing water temperature not more than 1150C. Grain warehouse must have a stationary system for water supply and sanitation.

The production objects of grain warehouse include: elevators and grain floor storage warehouses with complex of manufacturing equipment.

Elevator is granary, equipped with appropriate mechanisms and systems for lifting, drying and storing (10…150 thousands tones) of grain. There are the following types of elevators: grain linear elevators - taking grain from rural farms with a capacity of 15…100 thousands tones; manufacturing elevators, located near the mills and having capacity within 8…40 thousands tones, sometimes more than 100 thousands tones; basic and port elevators for long-term storage and reloading from one type of transport to another, built near large railway stations and ports with a capacity of 50…150 thousands tones; stock (fund) elevators for long term storage of the state grain reserve.

Elevator consists of multiple silos (containers) for grain storage. Silos is a ferro-concrete cylinder tower with the height of 30 …50 m and diameter of 6…10 m. Silos container can be also made as a steel cylinder with the height of 30 m and a diameter of 20 m. Grain from receiving containers is lifted to the silo-top floor, weighted, cleaned from impurities, dried and by conveyers poured to the silos. Grain is poured out through the funnel in the storage basement. Grain temperature is regulated on the all levels.

To provide storing crops services the grain elevator includes the following types of equipment: technological equipment for cleaning grain crops: peas cleaners, scalperator, sieve-air separators, air separators, magnetic separators, stone separators and magnetic separators; technological equipment for grain drying: concurrent grain dryers, recirculating grain dryer; technological equipment for active grain ventilation: equipment for active grains ventilation in warehouses and on the grounds (mobile, portable or stationary, and equipment for ventilation of grain crops in silos, hoppers, and metal container (stationary with vertically and horizontally grain blasting); instrumentation and automation: equipment for remote control of grain temperature in silos (system of  thermal control), devices for control and automation of core production processes. The grain warehouse must to have the reserve power equipment of necessary power to provide uninterrupted work.

Granaries store grain with medium dryness (with a humidity of 13,5…15,5%), humid grain (15,5…17%), wet grain (15.5 ...17%), raw grain (17 …23%), raw grain (over 23%) with intervals of 6%, and corn in grain - 5%.

The parts of cereal crops that needs in processing must be posed into separate metal silos. If necessary, the preventive measure for refreshing, cooling and drying of grain may be applied.

During grain storage period the warehouse conduct a systematic quality control of the grain mass specifying the following grain parameters: temperature, humidity, level damage by pest, smell and color of the grain. After identifying deviations in stored grain quality, the specific actions to improve it are performed. Grain warehouse provide grain storage in dry state, in a chilled (refrigerated) state and in leaked air conditions.

Storage of grain mass in the dry state allows reducing the physiological activity of biological components, when microorganisms and mites in practice are no developing, and biological ability of grain pests is reduced. Recommended humidity for cereals and legume crops should be 12…14%; for oilseeds (fat content 25 …30%) – 10 …11%, while for fat quantity of 40 …50% the humidity must be in the range of 6…8%. Dry state of grain mass allows: increasing grain storage to 3…4 years; transporting of grain by the and rail way, road and water ways over considerable distances; keeping grain in silos during 2…3 years, in warehouses - 4…5 years; guaranteeing practically invariable quality of grain.

Storage of grain crops in a refrigerated state also significantly increases the time saving of the grain lots. The grain mass with a temperature in all layers of 0…100C has first degree of refrigeration, and a grain mass with temperatures below 00C has second degree of refrigeration. The grain cooling to the low (-5...200C) temperatures is not recommended. The raw and wet grain masses are cooled. The technology of active and passive grain cooling is done, using cold air in the autumn-winter period as well as the cryogenic technique. Passive cooling of grain mass is carrying out using the ventilation channels in the granary. At active cooling a cereal mass is transmitting through separators, grain dryers, equipment with installed ventilators, as well as the settings for the active ventilation of grain are used.

A grain mass storage in leaked air conditions is reached with a natural accumulation of carbon dioxide in the containers (silos), with losses of oxygen at aerobic breath of grain mass organic components, and introduction of the inert gases into cereal mass, which supplant the air from the grain.

The grain drying is produced in the cases, if it necessary to reduce humidity of the grain to the standard quality, improve the grain, destroy pests of grain, cool grain at it self-heating, fresh up grain, improve his appearance (color and gloss).

A direct-flow technology for grain crops drying includes: selection of grain lots with a difference of grain humidity of 2 …3%; transmission of raw or moist grain by transport mechanisms originally separated into the hopper of the dryer; drying of the grain according to the parameters of the first zone; drying of the grain according to the parameters of the second zone (temperature of grain at the end of the drying process does not exceed the permissible value for this culture); grain cooling with outside air; issue of grain from dryer; control of the temperature of the cooled grain; control of grain humidity after drying process and feed of dried grain into one of the granaries capacity. A direct-flow drier for one passage reduces moisture of grain for 6 …8%. To reduce the moisture for more than 8% the grain is transmitted through a drier 2 ...5 times with operational control of its quality. Dry grain is guided for secondary cleaning or into a capacity of the granary.

Recirculation technology for drying cereals does not need in the choice of grain lots with different humidity.  It provides: automatic directing of originally cleaned wet or humid grains into drier; mixing of moist grain with recirculated grain, which should be two to three times larger in volume in comparison with wet grain one; heating of the grain mass to a necessary temperature; maintaining of the temperature in the insulated container during 15…20 minutes to ensure heat exchange between dried and humid grain mass; direct-flow drying or cooling of grain masses in mining driers; temperature control of drying agent; issue of dry grain from dryer and distribution of dry grain (about 2/3 of the total quantity is given  for recirculation, and 1/3 - into granary).

In the cleaning technological lines the next equipment are used: sieve-air separators; controlling separators of the grain removing from a waste; stones separators; trieurs (cockle removers) and magnetic separators.

The cleaning equipment provides selection of impurities (not less than) with the separator (60%), chaff separator (80%), and stone separator (99%). The contents of cockle within the cleaned grain must not exceed of 0,5%.

Active ventilation of crops are used for: acceleration of the grain maturation process by directing the warm atmosphere air flow into the cereal mass; grain mass drying (humidity of grain before drying can not be more than 10% (sunflower), 13% (rapeseed) and 17% (wheat, rye, rice, corn, soybean, peas); cereals refreshing (grain airing) without their move; lowering of the grain mass temperature (cooling of grain) at a temperature of external air below the temperature of grain not less than 50C; preventing or eliminating the grain self-heating; removal from the grain mass of not healthy smells; slowing down of the grain pests life  by cooling process; degassing (decontamination) of grain crops.

Grain cleaning, drying, active ventilation and cooling of grain crops are the main power-intensive technological processes that are used in the granary during grain storage. The cost of fossil fuel in the total cost of grain drying process is within 80…90%. 

Priority energy-saving measures at the work of the granaries are improvement of the power equipment, employment of unconventional sources of energy (wind, Sun, biogas) for the production of thermal and electrical energy. The main indicators of the grain storage complexes effectiveness are reduction of the electricity and energy resources and growth of the part of autonomous power supply in the total energy balance. The employment of renewable energy reduces approximately 2 times the external energy supply. Unfortunately, power systems that use alternative sources of energy have a number of shortcomings: occupy large areas, depend on the weather, time of day and season. The use of alternative energy sources today requires enhancing of energy efficiency for the power systems, creating new constructive solutions, unification in a single system of several technologies for energy production.

Autonomous wind power system is very promising for heat supply of granaries. The system for heat supply of the granary must accomplish the following functions:

 

·     autonomous power production with the use of renewable energy sources to greatly reduce the consumption of organic fossil fuel;

·     storage of heat produced in the presence of wind in special thermal accumulators to use it in the night time;

·     drying of grain;

·     cooling of grain;

·     ventilation of grain;

·     purification of grain by air flow;

·     electrical energy supply to equipment;

·     parallel work with other traditional equipment for thermal and electric energy generation: water boiler, steam boilers, thermal generators and cogeneration systems;

·     accounting during work of numerous external climatic indicators collected with the sensors of speed and wind direction, air temperature, illumination, humidity, presence and intensity of rain, cloudiness, position of the Sun;

·     accounting of the internal parameters of granary: temperature and humidity of grain and air in different parts of the granaries, concentration of carbon dioxide and methane;

 

 

By Vasil Sidorov on October 15, 2012

Technopark QUELTA, Queltanews from

Nizhyn Laboratories of Scanning Devices

sidorovvasil@gmail.com

 


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