| WO/2009/140751 | DISPOSTITION IN CENTRIFUGE BLOWER FOR GRAIN AERATION SYSTEMS |
| WO/1994/017654 | WALL ELEMENT PROVIDED WITH VENTILATION PASSAGES |
| WO/1994/012013 | PROCESS AND DEVICE FOR DRYING GREEN FODDER |
CLAIMS
1. EQUIPMENT UPGRADE FOR
ARTIFICIAL COOLING OF GRAINS AND SEEDS, composed by one or more group (s) of compressors (1.A), (1.B), (1.C) e (1.D) operating in independent circuits, condenser coils (2), evaporator's pre-cooling coil with two independent refrigerating circuits (3) in series with post-cooling coil with two independents refrigerating circuits (4), axial condensation fans (5), centrifugal "limit load" fan with blades curved to the back for air movement of the process' variable (6), temperature sensor Pt 100 for air temperature monitoring at the evaporator's outlet (7), PID air temperature controller at the evaporator's outlet (8), frequency inverter for monitoring the flow of air at the centrifugal fan (9), air temperature sensor at the evaporator's outlet (10) and the improvements with the following new components: three-stage air temperature controller at the evaporator's outlet (11), programmable logic controller PLC (12), gas temperature sensors at the gas line at the evaporator's outlet for freezing detection (13), temperature controller for freezing monitoring (14), pressure switch to monitor the pressure at the liquid line to monitor the axial fan and protect against freezing (15), temperature sensor for the air outlet of the condenser (16), PID controller of the condenser's fan (17), frequency inverter for the condenser's air flow monitoring (18), pre-heating coil (19), pre-heating air temperature sensor (20), PID controller for monitoring the flow of coolant gas at the pre-heating coil (21) and gas coolant variable flow control valves (22);
2. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, air inlet pre-heating coil (19), together with the air preheating temperature sensor (20), PID controller for monitoring the flow of coolant gas in the pre-heating coil (21) and coolant gas variable flow control valves (22), for indirect humidity monitoring of the post-heating evaporator outlet (4), as well as the operation in colder climates, with low enthalpies and high relative humidity, adopting set-point adjustments of the PID controller (21), between 20 0 C and 30 0 C;
3. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, peripheral speed of the centrifugal fan (6) lower than 70m/s and the exhaust speed lower than 15m/s;
4. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, centrifugal fan (6) positioned after the pre-heating coils group (19), evaporator's pre-cooling coil (3) and evaporator's post-heating coil (4);
5. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, speed of the air inlet flow at the evaporator's coils (3) and (4) and pre-heating (19) should be lower than 6m/s;
6. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, temperature set-point adjustment of the evaporator's air outlet temperature PID controller (8), is higher than 6 0 C and lower than 15 0 C;
7. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to claim 1, characterized by, three stage controller (11) to modulate the refrigerating capacity with actuation settlement of its three stages: Stage 1= Set-point - 3 0 C, Stage 2= set-point -2 0 C, stage 3 = set-point -I 0 C, where the set-point is the PID controller (8) operating adjustment temperature;
8. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to Claim 1, characterized by, temperature controller's (13) to prevent freezing problems at the evaporator's coils (3) and (4), with adjustment between -2°C to +5 0 C;
9. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to Claim 1, characterized by, condenser's (5) fans air flow monitoring, with the settlement adopted for the PID controllers (17) set-point temperature value found between 25 0 C and 35 0 C;
10. EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, according to Claim 1, characterized by, programmable logic controller's PLC (12) algorithm for compressor's interchange when actuating any of the controllers (14) or (11), where the timing for interchange is of 15 to 30 min. |
EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS
Refers to the present invention the improvement on an electric equipment that supplies cooling artificial air of grains and seeds in bulk, mobile or stationary, composed by a new automated control system and new shape of the coils that maintain humidity and temperature of the primary air in a safe variation range to the purpose for which is intended, independently of humidity and temperature of the ambient air. Advanced automatic control, allow fine modulation of refrigeration capacity, suction pressure control, control of the variable flow of air in the condensation coil and project parameters that allow safe operation under different climatic conditions and storage structures. These innovations also bring great advantages to control the air outlet humidity and avoid freezing of the evaporator's coils.
As it is common knowledge of the technical means connected to the agricultural sector, notably the storage segment of grains and seeds demands solutions for the reduction of losses and maintenance of physiological and sanitary quality of the products, from the harvest until its processing or use in sowing (the case of seeds). The artificial cooling stands out as an important alternative to assist in this task, because it allows monitoring the temperature of the mass of grains and/or seeds throughout the period of storage, exempting the use of dangerous chemicals, for both, human and animal health, and reducing the losses of storage.
European equipments were installed in
South America, and demonstrated operational problems especially due to the reduced frontal area of the evaporator's coil which speeds up the air passage in inadequate levels for correct air dehumidifying. Due to the evaporator's coil geometry, it must be manufactured with great depth, to meet the requirements for refrigerating capacity which brings serious consequences for the removal of dust which incrusts within, restricting the flow of air and causing the coil's freezing and often totally disenabling the equipment.
Also, the great depth of the coil requires the use of higher pressured fans and consequently greater peripheral speed, which rises undesirably the air exhaust temperature due to friction with the fan's blades and air compression.
These project features may cause high air humidity on the equipments outlet, reason why post-heating coils are installed, with the aim of adding sensitive heat and thus artificially reducing the outlet relative air humidity to compatible levels for cereal cooling. The increase of the static pressure of the centrifugal fan brings an exponential increase of the engine's electric power that increases the electrical energy consumption.
The refrigeration capacity modulation with fractionary engines brings disadvantages under the energetic and operational point of view, since the same electrical engine should activate the compressor's axis, being it empty or fully-loaded.
On the Brazilian Patent PI0400535-0 of the same author of the present request, it revealed improvement on the refrigeration system aiming to ameliorate its adaptability to different climatic operating conditions and to different structures for grains and seeds storage.
New improvements allow extending the use
of this technology to large sized structures such as silos and storehouses, being possible nowadays cooling of great masses of grains 50000 to 200000 tons and Seed Processing Units from 4 to 60ton/h process flow, as well as its safe operation in environments with low temperature and high relative humidity.
The conventional cooling systems use atmospheric air attempting to lower the mass of grains and/or seeds' temperature, but depending on the geographical region (and the season of the year) where the storage facility is found, the environmental conditions can be very severe (hot and humid), which limits this technique's application.
The determining factors for the maintenance of physiological, sanitary and nutritional qualities of stored grains and seeds are: temperature, humidity and time. Fungi and insects are the main cause of stored seeds and grains quality loss and need humidity and temperature to reproduce and survive.
Therefore the effort in drying and reducing the product's temperature, to prevent the action of these pests
According to Lazzari, Flavio Ph.D, "the seeds or grains may suffer great alterations on their sanitary and physiologic characteristics; germination and vigour since maturation, from the field until the moment of its use. These alterations are caused mainly by grains or seeds humidity and temperature, isolated or associated, they are the main factors that affect fungi and insects development in stored products, and even more due to inadequate extraction, reception, drying and storage of the products.
Fungi and insects, whose development is associated with humidity and temperature, separately or combined, can damage direct or indirectly seed or grain quality, and they are classified as follows:
Contaminations: presence of these organisms in grains or seeds;
Reduction of the germination capacity and vigour as a consequence of the action of fungi such as the Aspergillus that contaminates the individual grain or seed of different species when its moisture content is near the upper limit considered safe for its storage. The insects affect germination by consuming its embryo.
Mass Heating: fungi's and insects' metabolic activity increases seeds' and grains' mass temperature, causing a decrease on their germination capacity and vigour;
Discard of seed lots: occur mainly due to germination problems;
Marketing costs: seeds presenting sanitary and physiologic problems increase selling costs;
Reputation loss: loss of market due to low quality, seeds are returned, compensation, and undermining the trademark and the name of the company;
Fungi are abundant in soil, in culture leftovers, hoppers, silos and in every place where it's possible to store or process seeds. The attack or contamination of seeds by fungi {Aspergillus, Fusarium and Penicillium) occurs specially during the harvest, reception, drying and storage. Therefore, it is unlikely and definitively not practical, attempt to avoid that the seeds come into contact with the fungi spores. But it is possible to prevent their growth in newly harvested seeds.
These seeds are found (humid, dirty and hot) and when kept in drays, body trucks or in hoppers, they are quickly invaded by storage fungi.
The main responsible factors for fungi
growth are the seeds' humidity and temperature. The storage period is also important, because the longer is the stocking period, the bigger are the risks that the seeds are exposed to. The fungi present in the seed creates humidity conditions to maintain its growth and damage the seeds without being noticed with the naked eye.
The most important fungal toxins - aflatoxins, fumonisins and ochratoxin - produced by certain species of Aspergillus, Penicillium and Fusarium, are usually monitored by food industry using discarded seed lots.
Table 1 shows the ratio: moisture content and seed temperature/ fungi growth speed and safe storage period, i.e., without damaging the products' quality."
Table 1
MC % T ( 0 C ) Development Storage period
12,00 15 Inexistent 2 to 3 years
12 - 13,0 16 - 18,0 Very slow 1 or more years
14 - 15 20 - 25,0 Moderate 6 months to 1 year
15 25 - 35,0 Fast 1 to 2 weeks
The seeds sector faces difficulties and major losses due to the problem of maintaining the germination capacity and vigour of seeds, during the period of storage.
To solve this problem temporarily, during the last decades, the production of seeds migrated to high altitudes, seeking milder temperature and humidity on the field and during storage. This brings serious limitations of seeds' producing areas, considering that nowadays the earlier varieties are not adapting well to high altitudes. These varieties are often requested by farmers. The solution then requires producing seeds in lower altitudes, with temperature and humidity problems already known. This problem becomes worse with the expansion of the agricultural border in the Northern, Northeastern and Central-western areas, where the temperatures and humidity are higher. Another difficulty is the fact that the varieties from the Southern and Southeastern areas cannot adapt to those regions.
The solution consists on developing equipment and technologies that allow controlling seeds' temperature and humidity, independently of the geographic and environmental conditions, during the whole storage period.
EQUIPMENT UPGRADE FOR ARTIFICIAL COOLING OF GRAINS AND SEEDS, object of the
present patent were developed to overcome the limitations, disadvantages and inconveniences of the current equipments and Technologies, due to the fact that it provides improvement to electric equipment for artificial cooling air supply of grain and seeds, to monitor the outlet air humidity and temperature, independently of the geographic, climatic and environmental conditions, bringing advantages of avoiding freezing, increasing the cooling speed, optimizing the air dehumidification and consequently higher energetic efficiency, with flexibility and adaptability in any storage structure.
In addition brings solutions through a wide frontal area of its evaporator's coil which reduces the speed of air flow to adequate levels for correct air dehumidification. The coil's geometry, produced with less depth, brings substantial advantages for dust removal that encrusts in its interior, because it facilitates mechanical cleaning, avoiding unwanted coil's freezing
Also, lower coil's depth allow the use of lower pressured fans and consequently lower peripheral speed, which reduces the exhaust air's temperature by less friction on the fan's blades and lower air compression.
These new project features, allow improving the air humidity removal efficiency, reason why it is not necessary to install post-heating coils, avoiding unnecessary outlet air heating. The centrifugal fan's static pressure reduction, permits exponential reduction of the electrical engine's power which reduces the electric energy consumption in about 50%.
The refrigeration capacity modulation proposed in this patent request, using tandem compressors and/or refrigerating independent circuits, brings great advantages under the energetic and operational point of view, because in this case, the electrical
power is also proportionally fractionated, besides being compressors of easy- purchasing in any market, and of easy replacement on field.
Finally, to optimize the dehumidifϊcation of the air outlet, avoiding unwanted operating conditions on weathers with the lowest enthalpies, by installing the pre-heating coil of the evaporator's air inlet, adding sensible heat on the necessary proportion for good equipment's performance.
For best comprehension of the present patent, the figures bellow are attached:
FIGURE 1., shows a section of the superior view with the main constituent parts of the perfected equipment of the present patent;
FIGURE 2., shows a section of the side view with the main constituent parts of the perfected equipment of the present patent;
FIGURE 3., shows a diagram of the automation and monitoring system with the main components and with the refrigerating connections between two compressors and the evaporator's post-heating coil, so as the pre-heating coil;
FIGURE 4., shows a diagram of the automation and monitoring system with the main components and with the refrigerating connections between two compressors and the evaporator's preheating coil.
According to the mentioned figures, the air supply refrigerating electric equipment for grain and seed's cooling is endowed with the following conventional components: one or more group (s) of compressors (1.A), (1.B), (1.C) e (1.D) operating in independent circuits, condenser coils (2), evaporator's pre-cooling coil with two
independent refrigerating circuits (3) in series with post-cooling coil with two independents refrigerating circuits (4), axial condensation fans (5), centrifugal "limit load" fan with blades curved to the back for air movement of the process' variable (6), temperature sensor Pt 100 for air temperature monitoring at the evaporator's outlet (7), PID air temperature controller at the evaporator's outlet (8), frequency inverter for monitoring the flow of air at the centrifugal fan (9), air temperature sensor at the evaporator's outlet (10) and the improvements with the following new components: three-stage air temperature controller at the evaporator's outlet (11), programmable logic controller PLC (12), gas temperature sensors on the gas line at the evaporator's outlet for freezing detection (13), temperature controller for freezing monitoring (14), pressure switch to monitor the pressure at the liquid line to control the axial fan and protect against freezing (15), temperature sensor for the air outlet of the condenser (16), PID controller of the condenser's fan (17), frequency inverter for the condenser's air flow monitoring (18), pre-heating coil (19), pre-heating air temperature sensor (20), PID controller for monitoring the flow of coolant gas at the pre-heating coil (21) and gas coolant variable flow control valves (22).
Each compressor or group of compressors operating on tandem, are connected to the respective evaporator and condenser coils, by independent refrigerating circuits, so for example (see Figure 3) the compressor (LA) and (LB) can feed the post-heating coil of the evaporator (4) and the compressor (LC) and (LD) can feed the preheating coil of the evaporator.
The compressors (1) that feed the post - heating coil (4), in this case (see Figure 4) compressors (LA) and (LB) should necessarily feed the pre-heating coil (19).
The dimensioning of the equipments and
instruments will depend on the desired refrigerating capacity, however, the innovations' concepts of the present patent are based on premises and new components for its perfect operation:
1- Install air inlet pre-heating coil (19) with the purpose of carrying out "pre-stocking" of this air's temperature and relative humidity, together with the air pre-heating temperature sensor (20), PID controller for monitoring the flow of coolant gas in the pre-heating coil (21) and coolant gas variable flow control valves (22). These new components allow indirect humidity monitoring of the post-heating evaporator outlet (4), as well as the operation in colder climates, with low enthalpies and high relative humidity. Adjustments are made at the PID controller set point (21), between 2O 0 C and 3O 0 C.
2- The peripheral speed of the centrifugal fan (6) should be lower than 70m/s and the exhaust speed lower than 15m/s to avoid excessive air heating by friction and compression. With these data it is possible to win the static pressure of the grain column of up to 30m, typical on great part of the horizontal and vertical silos.
3- The centrifugal fan (6) is positioned after the pre-heating coils (19), evaporator's pre-cooling coil (3) and evaporator's post-heating coil (4), aiming to allow laminar flow of air and non-turbulent on its surface, as well as slightly adding sensible heat that allows keeping the air humidity in safe levels for cooling grains and seeds.
4- The speed of the air inlet flow at the evaporator's coils (3) and (4) and pre-heating (19) should be lower than 6m/s to allow adequate air dehumidification and smaller number of columns for mechanical cleaning of the coils. The same for the condenser's coils (2), where speeds lower than 4m/s, for the same purpose of mechanical cleaning, are also desirable.
5- The adjustment of the temperature set- point of the evaporator's air outlet temperature PID controller (8), should be higher than 6 0 C to avoid freezing of the evaporator's coils (3) and (4) and lower than 15 0 C to avoid high pressure at the liquid line at the condenser outlet (2), specially when ambient air should be cooled with high enthalpy.
6- The three stage controller's (11) function is to modulate the refrigerating capacity to lower ambient air enthalpies, and the settlement of the actuation of its three stages depend on the PID controller (8) temperature set point adjusting value. The following criteria has been adopted to adjust the three stage controller, considering the starting point as the set point value of the PID controller (8): Stage 1= Set-point -3°C, Stage 2= set-point -2 0 C, stage 3 = set-point -I 0 C.
7- The temperature controllers' (13) function is to prevent freezing problems at the evaporator's coil, by monitoring the evaporating temperature of the coolant gas and the information is transmitted to the PLC (12) which removes one or more compressors, keeping a constant interchange while risk exists. The settlement adopted for these controllers is between -2 0 C to +5°C.
8- The condenser's (5) fans air flow monitoring allows fine gas pressure control on the liquid's line, allowing safer operation on climates with low enthalpies. The settlement adopted for the PID controllers (17) set point temperature value is found between 25 0 C and 35 0 C.
9- The programmable logic controller's
PLC (12) algorithm should allow the compressor's interchange when actuating any of the controllers (14) or (11). The timing for interchange that was adopted is of 15 to 30 min.
The present patent's equipment operation is
carried out according to the following sequence:
At the equipment's startup, the PLC (12) executes the algorithm and, after complete check, it enables the connection of all the electrical engines. The centrifugal fan (6) after enabled by the PLC (12) spins on its minimum speed settled on the Frequency Inverter(9), the four compressors (1) or group of compressors (1) are manually switched on by the operator and the temperature created at the evaporator's outlet (7) is reduced by refrigerating action of the compressors, until it reaches the PID controller (8) set-point adjustment value, when this controller sends a signal of 4 to 2OmA to the frequency inverter (9) increasing the centrifugal fan's spin (6) until the generated temperature reaches the set-point value. At this moment the PID controller (8) interrupts sending the signal and the frequency inverter (9) maintains the centrifugal fan's spin (6) stable, keeping the air outlet temperature (7) within the desired operational limits in the evaporator. From this moment the operator's presence is no longer necessary because the equipment is then controlled automatically by the automation and monitoring system proposed on the present patent.