JPH0942840A - Fluidized bed type powder dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fine power and odor from being emitted into the atmosphere and increase the thermal efficiency of a dryer that is used to dry such high-moisture powder as bean-curd refuse, apple grounds, coffee grounds, sake lees, forage, etc. SOLUTION: Not only powder separated by a cyclone 4 but also almost all working air are circulated to a drying chamber 1 and the remaining portion of the working air is used as combustion air in a fuel combustion chamber 8 before discharged into the atmosphere to remove fine powder and odor. Heat generated in the combustion chamber 8 is recovered by fresh air to lower the temperature of the air to be released into the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device applied to the drying of high-moisture powder such as okara, apple dregs, coffee dregs, sake dregs, feed and dust.

[0002]

2. Description of the Related Art FIG. 3 is a conceptual diagram showing an example of a conventional fluidized bed type powder drying apparatus. Air heated by a burner in an air heater (15) is fed from a warm air nozzle (2) into a drying chamber (1) in which a layer of raw material powder is formed. The absorbed air passes through the absorbed air discharge line (3) together with part of the powder, and is solid-air separated by the cyclone (4). The separated solid content, that is, the powder, returns to the dryer (1) through the rotary valve (5), and the air is discharged as it is into the atmosphere.

[0003]

The high-moisture powder is heated by the air discharged from the hot air nozzle (2), and the moisture in the powder becomes vapor and moves to the air side. The powder is often a combustible substance, and in that case, if the air temperature is raised, the powder may be ignited and burned, so that the powder is dried with air (gas) at a relatively low temperature. The time required for the drying air to reach the outlet of the cyclone (4) from the outlet of the warm air nozzle (2) is very short. Therefore, the temperature drop of the air during that time is very small, and the thermal efficiency as a dryer is poor.

Further, since the exhaust gas is discharged to the atmosphere through the cyclone (4) after the powder is dried, the cyclone (4)
All of the fine particles and odors that were not captured in the air were also released into the atmosphere, which could be a problem for environmental protection.

It is an object of the present invention to remove fine particles and odor contained in exhaust gas of a fluidized bed type powder drying apparatus by combustion and improve thermal efficiency.

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventor has a drying chamber in which a powder layer is formed,
A warm air nozzle provided below the powder layer for ejecting warm air, a hygroscopic air discharge line having an upstream end opening at the upper part of the drying chamber, and a collector provided at the downstream end of the hygroscopic air discharge line. A dust collector, a means for returning the powder separated by the dust collector to the drying chamber, a combustion chamber for introducing a part of the air separated by the dust collector to burn fuel, and the dust collector The air return line that supplies the remaining air separated by the furnace to the hot air nozzle, the heat exchanger that heats the air taken in from the atmosphere by the combustion gas generated in the combustion chamber, and the heat exchanger. The present invention proposes a fluidized bed type powder drying apparatus characterized by comprising a means for releasing combustion gas into the atmosphere and a flow path for joining the air heated by the heat exchanger to the air return line. It is a thing.

The present invention has the above-mentioned structure, and introduces a part of the air separated by the dust collector to burn the fuel,
Since the heat exchanger for heating the air taken in from the atmosphere by the combustion gas generated in the combustion chamber and the means for discharging the combustion gas discharged from the heat exchanger into the atmosphere, the exhaust gas is in the atmosphere. Before it is released into the combustion chamber, it is used to burn fuel in the combustion chamber, where fine particles and odors are incinerated and purified. Further, the combustion gas exchanges heat with air in a heat exchanger, and the combustion gas itself becomes low temperature and is released to the atmosphere. Therefore, environmental problems are solved.

The present invention also provides an air return line for supplying the remainder of the air separated by the dust collector to the hot air nozzle, and a flow path for joining the air heated by the heat exchanger to the air return line. Since the amount of working air becomes huge, the residence time of air in the system increases and the thermal efficiency improves.

[0009]

1 is a conceptual diagram showing an embodiment of the present invention, and FIG. 2 is a perspective view showing a structural example of the heat exchangers (7) and (10) in FIG. In these figures, the same parts as those of the conventional one described with reference to FIG. 3 are given the same reference numerals to avoid redundancy, and detailed description thereof is omitted.

Also in this embodiment, one end of the hygroscopic air discharge line (3) is opened at the upper part of the drying chamber (1) in which a fluidized bed of the driving powder is formed, and a cyclone (at the other end is provided). Solid gas is separated by 4). The separated solid (powder) returns to the drying chamber (1) through the rotary valve (5), and the gas is blown by the circulation blower (6).

The air coming out of the circulation blower (6) is divided into two directions, part of which is guided to the first heat exchanger (7), and most of the other is passed through the air return line (12) and the hot air nozzle. It is sent to (2). The air exiting the first heat exchanger (7) enters the combustion chamber (8) and is used for combustion of the fuel supplied to the burner (9) provided therein, and becomes high-temperature combustion gas. .

The high-temperature combustion gas passes through the first and second heat exchangers (7) and (10), becomes low in temperature, and is discharged to the atmosphere. The first heat exchanger (7) exchanges heat between the hot combustion gas and the exhaust gas before combustion, and the second heat exchanger (10)
The heat exchange between the high temperature combustion gas and the fresh air taken in from the atmosphere by the pushing fan (11) is performed. The fresh air is supplied to the second heat exchanger (10).
After the temperature is raised by, it joins the air return line (12) and mixes with the circulating air to reach an appropriate temperature, and the warm air nozzle (2)
To the drying chamber (1).

Reference numerals (13) and (14) in FIG. 1 indicate dampers, blank arrows indicate fresh air, satin-finished arrows indicate hygroscopic air, and diagonal arrows indicate combustion gas.

[0014]

According to the present invention, the following effects can be obtained. 1) Since the working air and the granules circulate together, a huge amount of working air can be obtained compared to the new air amount. 2) The hot new air mixes with the working air in the circulation line, and only the hot new air does not come into contact with the powder, so that the powder is prevented from being burned. 3) Exhaust gas becomes combustion gas before it is released into the atmosphere, and fine particles and odors contained in the exhaust gas are removed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a structural example of a heat exchanger in FIG.

FIG. 3 is a conceptual diagram showing an example of a conventional fluidized bed type powder drying apparatus.

[Explanation of symbols]

 (1) Drying chamber (2) Warm air nozzle (3) Hygroscopic air discharge line (4) Cyclone (5) Rotary valve (6) Circulating blower (7) First heat exchanger (8) Combustion chamber (9) Burner (10) Second heat exchanger (11) Pushing fan (12) Air return line (13), (14) Damper (15) Air heater

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F26B 17/10 B01D 53/34 116H 23/02

Claims (1)

[Claims] 1. A drying chamber in which a powder layer is formed, a hot air nozzle provided below the powder layer for ejecting warm air, and a moisture absorbing member having an upstream end opening at an upper portion of the drying chamber. An air discharge line, a dust collector provided at the downstream end of the hygroscopic air discharge line, a means for returning the powder separated by the dust collector to the drying chamber, and air separated by the dust collector A combustion chamber for introducing a part of the fuel to burn the fuel, an air return line for supplying the remaining air separated by the dust collector to the warm air nozzle, and air taken in from the atmosphere in the combustion chamber. A heat exchanger that is heated by the generated combustion gas, a means that discharges the combustion gas that has exited the heat exchanger into the atmosphere, and a flow path that joins the air heated by the heat exchanger to the air return line. A fluidized bed type powder drying apparatus comprising: