RU2460025C1 - Multi-sectional sand sugar vibration dryer - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: immediately from the centrifuges, sugar is delivered into the upper vibroactive tray wherefrom it is sifted over onto the lower tray and further into the discharge device. The trays perform antiphase asymmetric oscillations due whereto sugar is poured from one tray onto the other. Occurring on the upper tray are the sand flow equalisation, the flow parameters equalisation and drying at a constant rate without supply of heat. Completed on the lower tray are drying at a constant rate without supply of heat, drying at a dropping process rate with additional contact supply of heat from a steam chamber and sugar cooling. The air flow in the dryer is organised, through the exhaust blower operation, in the direction opposite to that of sugar movement.

EFFECT: design simplification and reduction of electric thermal energy expenditure on drying.

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Description

The invention relates to the drying of granulated sugar and can be used in food, chemical and other industries.

The traditional method of air convective drying is known, which is implemented in industrial drum-type drying and cooling plants SBU-1 (see pages 807-808 Antipov S.T., Kretov I.T., Ostrikov A.N., Panfilov V.).

A known method of drying granulated sugar in a fluidized bed, implemented in an industrial dryer SPS-20 (see pages 125-130 "Chagin OV Equipment for drying food [Text] study guide / Ivanovsky, state chemical chemistry. Univ. Ivanovo, 2007, p.138 ").

The disadvantages of this method are the high energy consumption for creating a fluidized bed and heating the air, abrasion of sugar in the fluidized bed.

Known industrial dryer fluidized bed for sugar SPS-20, consisting of a prismatic casing, divided by a partition into the drying and cooling sections, containing in the lower parts an inclined sugar-containing and air distribution grilles with gates, discharge and loading gate gates, nozzles for supplying hot and cold air, and also suction collectors and exhaust pipes.

The disadvantages of the known dryer: structural complexity of the apparatus; high energy consumption for creating a fluidized bed and heating the drying agent.

Known multi-sectional vibration dryer for dispersed and adhesive materials (RF patent No. 2312286, publ. 2007.12.10), comprising a housing consisting of two sections connected by a conveyor and mounted on vibration-insulated frames, in each section there is a vibroactive lattice with rigidly fixed in staggered by hollow electric heating pipes, a variable cross-section duct for supplying gas along its entire length from below and a lid hermetically connected to the lock feeder and lock discharge devices m having the ability to change the inclination angle of inclined springs mounted on and connected to the exhaust fan, the gas feed compartment, and the individual vibrator including a crank mechanism and a motor.

Disadvantages: structural complexity of the apparatus; high consumption of electrical energy to create vibrations during transportation of the material; high heat consumption for drying.

The technical task of the invention is to simplify the design of the apparatus; reduction of electric heat energy consumption for drying.

The technical result is achieved in that in a multi-sectional vibratory dryer containing a frame, a housing, a lid, two vibroactive trays, an unloading device, an exhaust fan, a crank mechanism and an electric motor in the lid of the dryer for feeding sugar to the upper tray, loading funnels with hinged shutters, the lower tray is equipped with a steam chamber, the crank mechanism is pivotally connected to the trays by rods, and the trays are mounted on a frame with sliders.

Figure 1 schematically shows a General view of a vibratory dryer.

The vibratory drying installation comprises a frame 1, a housing 2, a cover 3, two vibroactive trays 4 and 5 with sides 6 and 7, an unloading device 8, a fan 9, a crank mechanism 10, an electric motor 11, loading funnels 12 with hinged shutters 13, a steam chamber 14, rods 15, sliders 16 and 17, nozzles for fresh air inlet 18 and exhaust air outlet 19.

The dryer operates as follows.

Sugar directly from centrifuges through loading funnels 12 with hinged locks 13 enters the upper vibroactive tray 4. Crank mechanism 10 creates trays 4 antisymmetric oscillations for trays 4 and 5, due to which sugar moves to the upper tray 4 to the left and is poured overboard 6 to the lower tray 5 and moves to the right along it, and then is poured overboard 6 into the unloading device 8. The movement of air in the dryer is organized by the operation of the exhaust fan in the opposite direction to reducing the flow of sugar. In this case, air from the production room enters the dryer through the fresh air pipe 18, penetrates the sugar stream flowing from the lower tray 5, passes over the lower tray 5, penetrates the sugar stream flowing from the upper tray 4, passes over the upper tray 4 and fan 9 through the exhaust pipe 19 is thrown out of the premises.

The sides of the 6 trays 4 and 5 have the ability to change the angle and are designed to adjust the thickness of the sugar layer on the trays. The sides of the 7 trays 4 and 5 are designed to prevent sugar from pouring from the trays. The slider 16 provides vertical movement of the end of the connecting rod, and the slide 15 - horizontal movement of the trays 4 and 5 (RF patent No. 2378174, publ. 10.01 2010). Case 2 provides a contact supply of heat to the dried sugar.

Sugar drying takes place as it moves and through the trays as a result of washing it with an oncoming air stream, mainly due to the heat of hot sugar coming from centrifuges.

On the upper tray, in a stream of sugar pouring onto the lower tray, and on the part of the lower tray to the steam chamber, drying passes at a constant speed to a critical humidity, corresponding to the transition of a constant drying speed to a falling one. Drying to critical humidity is solely due to the heat of hot sugar coming from centrifuges. In this case, the sugar temperature decreases, which leads to a rapid decrease in the further drying speed.

To increase the intensity of the process after critical humidity, the proposed installation provides for the supply of additional heat supplied from the steam chamber by the contact of the sugar stream with the surface of the tray. Thus, the part of the lower tray equipped with a steam chamber is intended for drying sugar from critical to the required values of final humidity.

The remainder of the lower tray is designed to cool the sugar with countercurrent air flow. The cooling process is completed in a stream of sugar, pouring into the unloading device, its penetration by a stream of fresh air.

The use of additional heat supplied directly to sugar and a countercurrent flow pattern of air and sugar flows allows the sugar to be dried on the proposed device to the required parameters.

Simplification of the design on the proposed device is achieved by eliminating the conveyor between the sections and using a single vibrator.

Energy saving is achieved by eliminating the vertical component of vibrations of vibroactive elements and by the absence of the need to raise sugar when moving from one section to another.

Saving thermal energy for drying is achieved by using the excess heat content of sugar coming from centrifuges and eliminating the heat consumption for heating the air. The installation of a steam chamber in the proposed device is intended to intensify the process in the period of the falling drying speed. In this case, heat is supplied directly to the dried sugar.

The sufficiency of the heat supplied with sugar from centrifuges to the evaporation of moisture is confirmed by the heat balance of the process.

When the initial moisture content of sugar u _n = 1.00% and the final - u _to = 0.04% the amount of moisture removed per 1 kg of dried sugar (p.315 in the manual Pavlov KF, Romanov PG, Noskov AA Examples and tasks in the course of processes and apparatuses of chemical technology. L .: Chemistry, 1981, 624 pp.)

At a temperature of sugar discharged from centrifuges t _n = 70 ° C and from a dryer t _k = 25 ° C, the heat capacity of sugar (from 14. to Zabrosin A.F., Dmitryuk A.A. Drying and cooling of granulated sugar in a fluidized bed . M.: Pishch. Pr-t, 1979, - 104 pp.)

c _n = 0.994 + 0.0072 · t _n + 0.293 · u _n = 0.994 + 0.0072 · 70 + 0.293 · 1 = 1.791 kJ / (kg · g)

and

The heat released during the cooling of sugar is defined as the difference between the enthalpies of sugar at the inlet and outlet

This heat is consumed for the evaporation of moisture from sugar, heating of air and loss to the environment.

As is known (p.135 in Ginzburg, AS, V. A. Rezchikov. Drying of food products in a fluidized bed. Food. Pr-article: 1966, 196 p.), Sugar moisture is mainly intercrystal and is part of syrup enveloping the surface of crystals. Intercrystal moisture is free, and its removal is governed by the laws of evaporation of water from a free surface. According to these laws, the temperature of the wet thermometer is set on the surface of the dried material in a period of a constant speed of the drying process, and ambient air does not heat up during drying. Air heating can occur only after the end of the period of constant drying speed. Thus, the heat consumption for heating the air in a first approximation can be neglected.

We take heat losses equal to 20%. Then the heat spent on the evaporation of moisture will be

Q _is = Q · (100-20) / 100 = 95.73 · 0.8 = 76.6 kJ / kg.

Possible amount of moisture removed will be equal to

W _max = Q _uc / r = 76,6 / 2382,5 = 0,0321 kg / kg

where r = 2382.5 kJ / kg is the specific heat of vaporization at a drying temperature of t = 50 ° C (M.P. Vukalovich, S.L. Rivkin, A.A. Aleksandrov. Tables of thermophysical properties of water and water vapor. Publishing house of standards : M., 1969, 408 p.).

The possible amount of moisture removed exceeds the required equal to 0.0097 kg / kg, 0.0321 / 0.0097 = 3.3 times.

It should also be noted that the proposed multi-sectional vibration dryer involves installation in production directly at centrifuges instead of vibrotransporters (shakers) used in conjunction with an elevator and belt conveyors to supply sugar to the drying compartment. The expected drive power of the proposed installation is comparable with the power of the shakers, and the heat consumption is lower than in analogues. At the same time, the production areas occupied by the drying department will be freed up, and the need for the use of shakers will disappear.

Claims (1)

A multi-section vibratory dryer containing a frame, a housing, a lid, two vibroactive trays, an unloading device, an exhaust fan, a crank mechanism and an electric motor, characterized in that loading funnels with hinged locks are installed in the lid of the dryer for supplying sugar to the upper tray directly from centrifuges , the lower tray is equipped with a steam chamber, the crank mechanism is pivotally connected to the trays by rods, and the trays are mounted on the frame with sliders.

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