A CONTINUOUS HOT AIR POPPING MACHINE USING FLUE GAS Technical Field
The present invention relates to a continuous hot air popping machine, for popping of cereals. The hot air popping device of the present invention is particularly useful for continuously popping maize, paddy, rice, and sorghum. The popping device of the present allows popping of maize, paddy, rice and sorghum under clean and hygienic conditions and the popped products are free from sand, ash and have uniform color, moisture and other sensorial properties. The popping device of the present invention also results in reduction in human drudgery.
Background Art
Popping machines that are in use till date for popping of maize, paddy, rice, and sorghum are of batch type. Hitherto the process of popping of maize, paddy, rice, and sorghum is done either in batch type sand roasters or in batch type popping machines. A patent search conducted by the Inventors showed that batch type popping machines for popping maize, paddy, rice, and sorghum are already patented.
The sand roaster type popping machine is shown in fig - 2. The sand roaster type popping machine consists of a mild steel pan (e) containing sand (f). The sand (f) is heated using rice husk or sawdust. Maize to be popped is taken in to the sand in the pan and mixed thoroughly with the hot sand using a sickle (g) for better heat transfer. After a few seconds of mixing/heating, the maize starts expanding/popping. The sand temperature is maintained by the skill of the operator. The popped material and sand are taken out in a sieve (h) and separated. The hot sand after separation is put back in to the pan and the popped material is cooled and packed.
Batch type popping machines are used for popping of maize. The batch type popping unit as shown in fig - 1 consists of a bowl (a), which can be swiveled for unloading of the popped material as well as unpopped material. The unit has a temperature controller (b) for controlling the temperature of the bowl. A predetermined quantity of maize, oil and spices (salt) are loaded in to the bowl. An electric heater (c), wound around the bowl heats the bowl. The popped material after popping starts pouring out of the bowl due to expansion. After the set batch time the bowl is tilted and the unpopped material (d), is unloaded. During the process of popping the oil and spices would adhere to the popped maize, which acts as a thin coat on the popped maize. All the contact parts of the batch type-popping machine are made of stainless steel.
The drawbacks of using the above types of popping machines are:
> There is no uniformity in popping. Maize, paddy, rice or sorghum cannot be popped in a single device. Popping of unsorted material is not possible. The popped material will not have uniform color.
> The product will have scorched / blackened particles. The end product will be contaminated with sand, sawdust and ash.
> The operation is tedious and the operator has to work under the threat of flame and smoke.
The major problems in these popping machines are non-uniform roasting, color, scorched and blackened particles, sand and ash entrapment after processing, which leads to poor quality product. These units are tedious in operation and the operator has to work under the direct influence of smoke and flame and also sand popping machines are not suitable for of maize and sorghum. Thus there is a requirement for providing a popping device for popping of maize, paddy, rice, and sorghum, which would result in reduction in hardship, clean and hygienic end product free from sand and ash and will have uniform color of popping etc and would largely benefit the industry. Realizing the importance and necessity, tne Applicants have successfully developed a device for continuous popping of maize, paddy, rice, and sorghum.
Objects of the Present Invention:
The main object of the present invention is to provide a continuous popping machine that uses flue gas for popping maize, paddy, rice or sorghum in a single device / machine.
Another object of the present invention is to popp maize, paddy, rice or sorghum hygienically through mechanized operations, using flue gas obtained from a continuous popping machine. Still another object of the present invention is to provide a device to produce popped maize, paddy, rice or sorghum having uniform color, texture and other sensorial properties.
Yet another object of the present invention is to provide a popping machine that reduces manual drudgery and increases productivity.
One more object of the present invention is to provide a device capable of working with a wide range of material to be popped.
Summary of the Invention:
Accordingly, the present invention provides a continuous hot air popping machine, for popping of cereals including maize, paddy, rice, and sorghum under clean and hygienic conditions to obtain a popped product that is free from sand, ash and having uniform color, moisture and other sensorial properties. The popping device of the present invention also results in reduction in human drudgery.
Brief Description of the Accompanying Drawings:
In the drawings accompanying the specification, Figure 1 represents the batch type popping machine.
Figure 2 represents the sand roaster type popping machine. Figure 3 represent the popping machine of the present invention.
Detailed Description of the Present Invention: The present invention provides a continuous hot air popping machine for popping cereals using flue gas, the said machine consisting: a combustion chamber (2) mounted with a centrifugal blower (3) at a bottom end and a perforated sieve (4) and a "U" shaped hood/popper chamber (5) at a top end, wherein said centrifugal blower supplies air to the combustion chamber at a predetermined velocity for fluidization and carrying off popped material out of the U shaped popping chamber; said combustion chamber being provided with a heating source (19) for heating the air being supplied by the centrifugal blower; said popping chamber (5) being provided with a continuous feeding mechanism comprising of a screw feeder (6) and a servo motor (7) at a place near the top end of the combustion chamber for feeding cereals and an outlet chute (11) at the other end; said centrifugal blower configured to receive exhaust gas from the outlet chute through a hot air return duct (13), said hot air return duct being connected between the outlet chute and the centrifugal blower through a tube fitting (12), the centrifugal blower being further provided with an inlet for controlling the velocity of the air supplied, said inlet being controlled by a swing door (9) provided with a tube fitting (10); a main frame (1) housing the combustion chamber, the centrifugal blower, the perforated sieve, the U shaped popper chamber, the feeding mechanism comprising of the screw feeder and the servo motor being outside the main frame and the centrifugal blower and the outlet chute being bolted to the main frame, and
said main frame being provided with an electronic panel (18) comprising a timer circuit (8) for controlling the feeding time, a temperature indicator (14) for indicating the temperature inside the combustion chamber and a main power switch (17) for switching
ON/OFF the operation of the machine.
In an embodiment of the present invention, the combustion chamber is cylindrical in shape and is made of stainless steel.
In another embodiment of the present invention, the U shaped popping chamber is cylindrical in shape and is made of stainless steel.
In yet another embodiment of the present invention, the U shaped popping chamber is fixed to the combustion chamber using means such as swing bolts and nuts.
In still another embodiment of the present invention, the U shaped popping chamber is optionally provided with a collar for ease in fixing.
In one more embodiment of the present invention, the screw feeder feeds the cereals onto the sieve.
In one another embodiment of the present invention, the cereals include maize, paddy, rice and sorghum.
In a further embodiment of the present invention, the screw feeder has variable feed rate.
In an embodiment of the present invention, the servomotor drives the screw feeder to feed the cereals on to the sieve.
In another embodiment of the present invention, the heating source is a LPG burner.
In yet another embodiment of the present invention, the main frame is provided with plurality of castor wheels (15) at its bottom for movement.
In still another embodiment of the present invention, the main frame is provided with covers (16) to cover the machine from all sides.
The device of the present invention overcomes most of the drawbacks of the existing methods of popping practiced.
The present invention is further described in detail with reference to the accompanying drawing 3 wherein an embodiment of the device of the present invention useful for continuous popping of maize, paddy, rice or sorghum using flue gas is shown. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention in any manner.
The continuous hot air popping machine using flue gas, comprises of a main frame (1) which houses all the parts of the machine. The combustion chamber (2) is mounted on the centrifugal blower (3), which is mounted on the main frame (1) through fasteners. A perforated sieve (4) and a "U" type hood/popping chamber (5) are mounted on the . combustion chamber (2) and are bolted together by suitable fasteners. The "U" type hood/popping chamber may preferably be in cylindrical in shape and made of stainless steel. This however, does not restrict the invention as any alternate shape or material can be used. The "U" type hood/popping chamber may be provided with a collar, which helps to fasten the hood with the combustion chamber. A screw feeder (6) and a servo motor (7) are used for feeding the raw material in to the popping chamber. The feeding of the raw material in to the popping chamber is controlled by a timer (8). The air velocity for fluidization as well as for carrying the popped material out of the "U" type hood/popping chamber (5) is by controlling the opening of the inlet of the centrifugal blower (3). The opening and closing of the inlet of the centrifugal blower is by means of a swing door (9), which also carries the tube fitting (10). The popped material is taken out of the popping machine by means of an out let chute (11). The outlet chute (11) is bolted on to the main frame (1) and carries a tube fitting (12), for connecting the hot air recirculation tube (13). A temperature indicator (14) is mounted inside the popping chamber for indicating the hot air temperature, is used for popping of different grains. All parts of the popping machine are mounted on the main frame (1) and the popping machine can be moved from place to place by means of a set of castor wheels (15). The popping machine is covered on all the sides by suitable covers (16). The timer (8), the temperature indicator (14), the main switch (17) are mounted on the main cover/electrical panel (18). A LPG burner (19) is fastened to the combustion chamber (2) for burning of LPG and generation of hot air. The materials of construction of the popping machine are preferably of stainless steel but this shall not restrict the use of other materials as well.
The Applicants propose a device useful use for popping of maize, paddy, rice, and sorghum for the first time according to this invention. The invention is based on the
finding that, popping of maize, paddy, rice, and sorghum is of uniform color and other sensorial properties under hygienic conditions by using this device.
Working of the Device: The raw material is fed in to the popping machine by a screw feeder is mounted on the "U" type hood/popping chamber of the popping machine. The feed rate of the raw material can be controlled by using a timer, which controls the rotation of the screw feeder. The material is popped to its characteristic flavour during its stay inside the "U" type hood/popping chamber above the perforated sieve. The temperature of popping can be varied to suit the raw material and its initial moisture content and the popped material is obtained at the outlet chute. The hot air is generated in the combustion chamber of the continuous popping machine by burning liquid petroleum gas. A blower mounted on the main frame generates a stream of air to be mixed with the flue. The generated hot air is blown across the perforated sieve mounted on the combustion chamber. Regulating the supply of LPG can vary the temperature of the hot air. The quality of popping can be controlled by varying the hot air temperature. Table 1 summarizes the process parameters for different food materials.
Example 1 The working of the popping machine is explained below with particular reference to popping of maize. The maize to be popped is fed in to the "U" type hood/popping chamber mounted on to the combustion chamber. The maize is fed on to the perforated sieve kept in between the combustion chamber and the "U" type hood/popping chamber at a feed rate ranging between 15 - 20 kg / h. The air velocity has been set at 1.3 - 1.4 m / s, at an air temperature ranging between 230 - 300 degree centigrade. The popped maize was discharged through the out let chute of the popping machine and collected on to the tray. The temperature of the popped material was around 80 - 85 degree centigrade with the final moisture of around 4 - 5%. Example 2
The working of the popping machine is explained below with particular reference to popping of paddy. The paddy to be popped is fed in to the "U" type hood/popping chamber mounted on to the combustion chamber. The paddy is fed on to the perforated sieve kept in between the combustion chamber and the "U" type hood/popping chamber at a feed rate ranging between 25 - 30 kg / h. The air velocity has been set at 1.5 - 1.8 m/s, at an air
temperature ranging between 230 - 300° centigrade. The popped paddy was discharged through the out let chute of the popping machine and collected on to the tray. The temperature of the popped material was around 70 - 85 degree centigrade with the final moisture of around 3 - 5%.
The popped material is free from contaminants like sand, sawdust ash etc. and the popping operation is carriedout in hygienic conditions. The product obtained after popping is uniform in color, texture and even unsorted raw materials can be used for popping. The startup / heatup time and shutdown time of the popping are rather instantaneous unlike other popping machines which need at least 25 - 30 minutes and the hot air is recirculated through the blower. The instant heat up of heat transfer medium and recirculation of hot air increases the thermal efficiency of the popping machine. The continuous popping machine using flue gas is suitable for popping of the wide variety of raw material like maize, paddy, rice, and sorghum, which is not possible in other types of popping machines. Different types of popping machines are needed for different raw materials and each has its drawbacks.
The main advantages of the present invention are
> Varying the temperature of the hot air admitted to "U" type hood/popping chamber could vary popping rate. No scorching / discoloration in the process using the device of the invention. Consequently there is no chance of non-uniformity in color. Even unsorted grains can be used for popping. The continuous popping machine is useful for popping of different varieties of maize, paddy, rice, and sorghum,
> The popping operation can be started or stopped by closing the screw feeder and by stopping the fuel supply.
> The popping process is continuous.
> The required temperature of the hot air can be varied to the requirement. The hot air temperature can be obtained with in 20 - 30 seconds and there is no heatup time. The hot air is recirculated to increase the thermal efficiency.
Table 1: Standardized process parameters for different Food Materials
The fuel consumption indicated above are without recirculation.