TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a dryer system for efficient and effective drying of maize kernels and in particularly relates to portable maize dryer.
BACKGROUND OF THE INVENTION
[0002] India produces about 258 million tons of food grain each year to feed the human population of the country. Rice - wheat is the major cropping system of north Indian states including Punjab which alone has about 2.9 M ha under cultivation for this cropping system. Repeated cultivation of these cereals has started affecting the soil health and put pressure on the important natural resources especially water. Therefore experts are advocating the diversification of agriculture by introducing other crops in the rotation. Maize is one of the cereal crops that can be cultivated in the northern states of India including Punjab. It is next to Rice, Wheat and Jowar in respect of area and production and India stood at 5* position with area of 68 lakh ha and in production, it stood at 6X position with production of 140 lakh tons during 2004.
[0003] The importance of Corn is due to its wide diversity of uses. It is used both as food for human and feed for animals. It is also fractionated either by dry or wet milling into food and industrial ingredients. The starch, the major constituent of the corn kernel, is used in foods and industrial products. The starch is also converted into glucose and

fructose for use as food sweetness. Glucose can be fermented into ethanol for fuel or beverages or into many other chemicals. It is estimated that about 2.45 percent of maize is lost at farmers' level during harvesting, threshing, winnowing and transportation.
[0004] To minimize post harvest losses, drying of cobs before threshing and kernels to safer levels before storage is vital. Drying is also important to avoid quality losses and deterioration. Sun drying of harvested grains by spreading on floor before marketing is usually resorted to by the farmers but it is very slow process that requires long periods and exposes the grains to infestations, insects, rodents and birds.
[0005] Therefore, there exists the need for a better solution for effective and efficient drying of maize cobs and kernels.
OBJECTIVES OF THE INVENTION
[0006] It is an object of the present invention to provide a novel portable maize dryer.
[0007] Another object of the present invention is to provide a maize dryer capable of reducing moisture content of harvested grains in order to store them safely and for optimum marketing.

[0008] Yet another object of the present invention is to provide an indirect, three pass diesel fired air heating system to raise drying air temperature in the range of 50 -90 degree Celsius.
[0009] Another object of the invention is to provide a maize dryer that dries grains gently at a rate of 1.25% /h with maximum rate of 2.66%/h.
[0010] Another object of the present invention is to provide a maize dryer that is cost effective due to less fuel consumption.
[0011] Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the present disclosure are described in detail herein and are considered a part of the present disclosure. For a better understanding of the present disclosure with advantages and features, refer to the description and to the drawings.
SUMMARY OF THE INVENTION
[0012] The invention provides for portable maize dryer for reducing the moisture of harvested grains. The ease, portability and gentle drying process of maize cobs and

kernels makes it superior over the present systems in the prior art. Further, the maize dryer dries grains gently at a rate of 1.25%/h with maximum rate of 2.66%/h in a fuel efficient manner.
[0013] The present invention discloses a maize dryer that is suitable for gentle drying as well as at high temperatures. Further, the dryer is suitable for drying maize, wheat, paddy etc.
[0014] The present invention provides a portable dryer system that can be fixed at a particular location. Further, the dryer can also be operated by AC electric power supply.
[0015] Further, the invention provides a dryer system that can easily be modified to make it more compact suitable for easy transport in case of adverse road conditions.
[0016] To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings and examples.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0017] The foregoing summary, as well as the following detailed description of various embodiments, is better understood when read in conjunction with the drawings provided herein. For the purpose of illustration, there is shown in the drawings exemplary embodiments; however, the presently disclosed subject matter is not limited to the specific methods and instrumentalities disclosed.
[0018] Figure 1 is a line diagram illustrating front view of maize dryer, in accordance with an embodiment of the invention.
[0019] Figure 2 is a line diagram illustrating side view of maize dryer, in accordance with an embodiment of the invention.
[0020] Figure 3 is a line diagram illustrating top view of maize dryer, in accordance with an embodiment of the invention.
[0021] Figure 4 is an operational view line diagram of maize dryer, in accordance with an embodiment of the invention.
[0022] Figure 5 is a line diagram illustrating top view of an indirect, three pass, diesel fired air heating system, in accordance with an embodiment of the invention.
[0023] Figure 6 is a line diagram illustrating front view of an indirect, three pass,

diesel fired air heating system, in accordance with an embodiment of the invention.
[0024] Figure 7 is a line diagram illustrating side view of an indirect, three pass, diesel fired air heating system, in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The presently disclosed subject matter is described with specificity to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different steps or elements similar to the ones described in this document, in conjunction with other present or future technologies. Moreover, although the term "step" may be used herein to connote different aspects of methods employed, the term should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly described.
[0026] According to an embodiment of the present invention, desired capacity, portable, cross flow, recirculation type maize dryer (300) has been designed. The said dryer consist of two concentric perforated cylinders of about 2.5 ft (inner diameter) -5.0 ft (outer diameter) (301) and about 1.25 m - 2.67 m (302) tall fixed in vertical orientation. The outer cylinder (301) is grain bin while inner cylinder (302) acts as

plenum chamber. The grains to be dried are held between the annular spaces of two cylinders with effective thickness of about 14 inch grain wall. The dryer is about 5 m high above the trolley frame (303). Maize dryer (300) has three sections namely grain holding / storage section (304), drying section (305) and feeding /discharge section (306). The dryer has adjustable height feeding augur (307) to move the grain into the dryer within one hour. The dryer has a central auger (308) rotating at about 150 rpm to re-circulate grain in one hour. The drying unit (305) is provided with indirect; three pass air heating system (309) with automated diesel fired single nozzle furnace. The burning of diesel is controlled by flame based optical sensor that accurately controls the heated air temperature to the set value. A 5 hp to 7.5 hp blower with variable frequency drive provide up to 5000 cfm of air flow with min static pressure of 4 inches of water. For efficient and economical operation a waste heat recovery exchanger (310) is provided to preheat the air going to the furnace. The dryer has preferably 15 KW alternator that operate with tractor PTO. A LT switch has also been provided to operate the dryer on electric power source without use of tractor.
[0027] The portable dryer (300) has been designed to dry the maize grain preferably from 25% moisture content to 15% moisture using heated air in the range of 70 to 60°C. The threshold value of various vital parameters like drying rate (1.0 -1.5 %), heating air temperature (60 - 95°C), grain temperature (40 - 45°C), air flow and fuel consumption

has been taken as the guiding points. For the flexibility and control of operation, gadgets like variability frequency drive (VFD) have been used. The dryer has drying chamber (305), inner cylinder/plenum chamber (302), Indirect air heating unit (309) with provision of heat exchanger for waste heat recovery that preheat incoming ambient air using heat of exhaust flue gases produced during combustion of diesel in furnace dust collection system (311). Other components include at least two augers for feeding and circulating the grains, alternator, and control panel. The size/dimensions of the dryer have been calculated using various physical properties of the maize grain and theory of drying. A centrifugal fan capacity has been worked out based on the quantity of grain to be dried, moisture to be removed and static pressure required. The electric motor power needed to run the blower, two conveying augurs, cyclone separator and diesel supply was summed up to arrive at the total electric load and consequently alternator of sufficient capacity has been provided. A 100 ltr diesel fuel tank is also provided with this machine. After the fabrication of the dryer, the dryer was run under no load conditions at fabricators site.
EXAMPLES
[0028] Trials were carried out at College of Agricultural Engineering and Technology for evaluation of the maize dryer for its performance to dry the grains, germination of dried maize and fuel consumption. Thirty five quintals of maize was

supplied by the PAU farm at Naraingarh for testing of this dryer.
[0029] The maize grains, herein as example, 35 quintals, were unloaded on to the feeding augur for taking it into the dryer column which took one hours time to feed the maize. The initial moisture content of a sample before loading was analyzed for its moisture content using universal moisture meter. It was observed to be about 14%. The dryer was run continuously for 5 and half hours with 60°C heated air temperature. The final moisture content of the grain sample was again analyzed and found to be at its lower limit of 8%. The operation of drying was repeated thrice and overall drying rate of 1.1 — 1.5 % per hour was estimated.
[0030] During the drying operation, the temperature of grain was noted down at regular intervals by inserting the mercury bulb thermometer at the port provided for this purpose. It was observed that the temperature of the grain varied between 40°C - 43°C. This temperature is well within the safe limit for using the grains for seed purpose.
[0031] Two 100 gm samples of the maize, one from fresh grain lot and another from dried grains were picked up and labeled as SI (fresh) and S2 (dried). These samples were sent to the Director Seeds for germination testing. Two samples were also tested in the department laboratory. The germination report after 15 days indicated 91% and 90%) germination respectively.

[0032] Consumption of diesel is very important for the economy of operation. Sixty liters of diesel fuel was filled into the fuel tank of the dryer at the start of the drying operation. The level of the fuel using dip stick was marked and noted down. After 5 hrs of drying operation at 60°C, the diesel consumption was estimated in the range of 2.5 -3.5 lt/hrs (Repeated thrice). The economy in the use of diesel is achieved with the installation of heat recovery unit for incoming air which heated up the inlet air by 12°C above ambient.
[0033] Table 1: Test Performance of the Maize Dryer

SNo Parameter Designed feature Actual Test Feature
1. Capacity of dryer: 3.0 ton/batch 2.8 ton/batch
2. Grain wall Thickness 14 inches 14 inches
3. Feed rate (kg/hr) 3000 kg/hr 3100 Kg/hr
4. Height of dryer on trolley Approx 5 m 4.425 m from ground
5. Fan Speed (variable with VFD) Max 2800 rpm at 50 hz Operates at 40 Hz with 2500 rpm
6. Power alternator/AC supply (KW) 16 (Reqd. 10) 15
7. Moisture content (Initial) 25% 14%
8. Moisture content (Final) 15% 8%
9. Ambient air temperature (°C) - 13
10. Inlet air temp, to heating unit(°C) Heat recovery system provided 25

11. Drying air temperature(°C) 60 °C - 95 °C 70°C
12. Temperature of exit air (°C) Should be near to ambient 40 °C
13. Grain temperature (°C) 40-45 43
14. Fuel consumption/batch at the rate of 8-10 lt/h (2.5-3.5) lt/h
15. Drying rate (% moisture/hr) (1.25-2.5)% 1.3% (14%-8%)/4.5
16. % Germination Fresh grain- 91 Dried grain - 90
[0034] Field Trial of Maize Dryer:
The maize dryer has been operated and tested in the new grain market at Rajpura mandi in Punjab. The maize grains harvested during month of June -July were dried in the mandi to validate the maize dryer in the presence of the grain traders and farmers. The results of the trial are summarized in Table 2 below:
Table 2: Field trial of maize dryer

SNo Day Quantity
of
maize
dried.
(Quintal) Moisture content (%, wb) Time
taken,
(hrs) Drying
temp.
(°C) Diesel
consumption
(Tractor &
Air heater)
(litre)

Initial Final

1 Dl 30 43 29 10 65 40
2 D2 30 29 15 10 65 40

3 D3 30 41.1 15 10 75 28
4 D4 30 37.5 15 09 75 30
5 D5 17 32 16 08 70 40
6 D6 20 56 20 08 85 10
7 D7 22.5 52 15.0 9.0 90 19.0
8 D8 25.0 25 10.0 9.0 75 21.0
9 D9 20.0 19-20 10.0 4.5 75 8.0
10 D10 25.0 30.0 12.0 4.5 90 9.0
11 Dll 25.0 50.0 35.0 5.0 90 15.0
12 D12 25 35.5 16.0 5 90 15.0
13 D13 25.0 18.0 15.3 4 45 Nil, by ambient air
[0035] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the present disclosure. Indeed, the novel methods, devices, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the methods, devices, and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the present disclosure.

Claim -
1. A portable maize dryer (300) capable of reducing moisture from harvested grains
wherein; the maize dryer (300) comprising:
an outer cylinder (301) having a predetermined height;
an inner cylinder (302) having a predetermined height; said outer cylinder (301)
and inner cylinder (302) are fixed in vertical orientation;
a trolley frame (303);
feeding augur (307) to move the grain into the said maize dryer (300);
central augur (308) to re-circulate the grain;
three pass air heating system (309) with automated nozzle furnace;
a waste heat recovery exchanger (310) to preheat the air entering the furnace;
wherein, the said outer cylinder (301) acts as grain bin; and
said inner cylinder (302) acts as plenum chamber.
2. The portable maize dryer (300) as claimed in claim 1, wherein said outer cylinder
(301) and inner cylinder (302) are concentric and perforated.
3. The portable maize dryer (300) as claimed in claim 1, wherein the grains to be dried are held between the annular space of outer cylinder (301) and inner cylinder (302).
4. The portable maize dryer (300) as claimed in claim 1, wherein the said portable maize dryer (300) has three sections; grain holding / storage section (304), drying section (305) and feeding /discharge section (306).

5. The portable maize dryer (300) as claimed in claim 1, wherein said feeding augur (307) has arrangement such that the height of said feeding augur (307) can be adjusted and the said feeding augur moves the grain into the dryer preferably within one hour.
6. The portable maize dryer (300) as claimed in claim 1, wherein the said indirect, three pass air heating system (309) includes automated diesel fired single nozzle furnace.
7. The portable maize dryer (300) as claimed in claim 1, wherein burning of diesel is controlled by flame based optical sensor that accurately controls the heated air temperature to the set value.
8. The portable maize dryer (300) as claimed in claim 1, wherein the portable dryer (300) removes moisture content of grains from 25% to 15% using heated air of 60° - 70°C.