JP2001000787A - Hot air type fiber dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent articles to be dried from discoloring/fading or turning into yellow by providing a low NOx means which makes the NOx concentration in the exhaust air a specified value or lower in a dryer wherein the combustion exhaust air of a gas burner is directly brought into contact with a fiber or a fabric. SOLUTION: A gas burner 2 is provided under a drying chamber 1 on the front surface of which, an opening/closing door is provided, and a hot air duct 4 which reaches a hot air inlet 3 provided on the upper surface of the drying chamber 1 from the gas burner 2, is provided. Then, the hot air which is taken in from the hot air inlet 3 is introduced from the upper opening of a circular frame 5 into a rotating drum 6 which is rotated in the circular frame 5, through a drum peripheral wall comprising a porous sheet, and a heat-drying of articles to be dried is performed. Then, the hot air is discharged from the lower opening of the circular frame 5 into the drying chamber 1, and discharged to the outside by a discharging fan 8 through a filter 7. At this time, the gas burner 2 is a low NOx burner which realizes a low NOx concentration of 20 ppm, and is constituted by providing a burner port plate on the front end surface of a mixing chamber to which a lean mixture having an air ratio of 1.3 to higher is fed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber dryer using a gas burner.

[0002]

2. Description of the Related Art Conventionally, indirect drying of steam has been mainly performed by steam boiler type indirect hot air drying. However, even when only a dryer is used, a large-capacity boiler must be operated.
When the load on other steam-using equipment increases, the steam supply pressure to the dryer decreases, and there has been a problem that the required amount of heat cannot be stably obtained. On the other hand, in recent years, gas hot air dryers have become widespread. This is to blow the combustion exhaust gas from the gas burner directly onto the cloth or fiber and dry it.
Since the boiler is not used, the dryer can be operated independently, and a stable temperature can be obtained and no startup time is required.
Moreover, there is an advantage that the thermal efficiency is greatly improved.

[0003]

However, in the gas hot-air system in which the gas is heated directly by the gas, the temperature of the combustion exhaust is high (1).
(50 ° C. or higher), there is a problem that the dyed fiber is discolored or faded, so that the type of the material to be dried is limited, or the drying time is long at a low temperature, and the drying of a high-grade color product Had a problem that it could not be adopted. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a direct-fire gas fiber dryer which does not cause discoloration or yellowing.

[0004]

A hot-air fiber dryer according to the present invention is a dryer in which the combustion exhaust gas of a gas burner is brought into direct contact with a fiber or a cloth, and the NOx concentration in the exhaust gas is reduced to 20 ppm (O ₂ = (Equivalent to 0%) is characterized by the provision of a low NOx means of not more than
As a result of various experiments performed by the present inventors, it has been found that the discoloration of the fiber is mainly caused by NOx in the combustion exhaust gas, and that the discoloration and discoloration hardly occur at a concentration lower than the NOx concentration of 20 ppm. Based on the findings, the present invention has been accomplished.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a hot-air fiber dryer according to the present invention, in which a drying chamber 1 having an opening / closing door (not shown) for taking in and out a material to be dried is provided at the front. A gas burner 2 is provided below, and a hot air duct 4 extending from the gas burner 2 to a hot air intake 3 provided on the upper surface of the drying chamber 1.
Are provided along the outer surface of the drying chamber 1. The hot air taken in from the hot air inlet 3 is introduced from the upper opening of the circular frame 5 into the rotating drum 6 that is driven to rotate in the circular frame 5 through the peripheral wall of the perforated plate, and heats the material to be dried. Thereafter, the drying chamber 1 is opened through the lower opening of the circular frame 5.
The air is then discharged through the filter 7 and further discharged to the outside by the exhaust fan 8. In the figure, 9 is a damper for adjusting the amount of hot air, 10 is a cooling damper for switching the ventilation path at the time of cooling, and 11 is a heat insulating material.

FIG. 2 shows the NOx used in the embodiment of FIG.
This figure shows a structure of a low NOx burner for realizing a concentration of 20 ppm. A flame hole plate 13 is provided at a front end face of a mixing chamber 12 to which a lean mixture having an air ratio of 1.3 or more is supplied. By providing a plurality of rows of concentric or parallel flame holes 14 in the perforated plate 13 and inclining at least one of the corresponding flame holes 14a and 14b of an adjacent flame hole row,
The flames collide with each other. By causing the flames to collide with each other to generate a turbulent flow, the axial flow velocity of the air-fuel mixture is substantially reduced to prevent lift and perform flame holding. By the flame method, a strong flame holding can be performed at a much shorter distance than in the past, and by completing the combustion with a short flame length as a whole, the time for exposing nitrogen gas to high temperatures can be significantly reduced. 20 ppm
An extremely low NOx concentration below (in terms of O ₂ = 0%) could be realized. The flame holes 14a and 14c in the figure
Are intersected with each other in the flame plate 13. Reference numeral 15 denotes a combustion cylinder.

FIG. 3 shows another embodiment, which is suitable for a dryer having a relatively large capacity as compared with the embodiment of FIG. 2, and has a NOx concentration of 20 ppm or less (O ₂ = 0% conversion). In order to realize the above, a NOx decomposition catalyst device 16 including a catalyst reactor 16a and a reducing agent inlet 16b is interposed in a hot air duct 4 extending from the gas burner 2 to the drying chamber 1. That is, in the hot air duct 4 extending from the gas burner 2 to the drying chamber 1, the catalytic reactor 16 filled with the NOx decomposition catalyst is filled.
a reducing agent injection port 16b for spraying and injecting the NOx reducing agent is provided upstream of the catalytic reactor 16a, and a NOx reducing agent such as urea water is injected into the high-temperature exhaust gas, and this is injected onto the catalyst. To react with NOx. 1 in the figure
7 is a metering pump for supplying urea water in accordance with the burner displacement, 18 is a compressor for compressing and injecting urea water, and 19 is a blower for cooling the nozzle in high-temperature exhaust gas.

[0008]

According to the present invention, as described above, a gas hot air type fiber dryer which is low in cost, requires no start-up time, and has high thermal efficiency is used. There is an advantage that even a color product can be dried at high temperature and in a short time without discoloration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the dryer of the present invention.

FIG. 2 is a sectional view showing an example of the burner used in the above.

FIG. 3 is a schematic system diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drying room 2 Gas burner 3 Hot air intake 4 Hot air duct 5 Circular frame 6 Rotating drum 7 Filter 8 Exhaust fan 9 Hot air volume adjustment damper 10 Cooling damper 11 Insulation material 12 Mixing chamber 13 Flame plate 14 Flame hole 15 Combustion cylinder 16 NOx decomposition catalyst device 16a Catalytic reactor 16b Reducing agent inlet 17 Metering pump 18 Compressor 19 Cooling blower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F26B 21/00 F26B 21/00 K

Claims (3)

[Claims] 1. A dryer in which combustion exhaust gas from a gas burner is brought into direct contact with a fiber or cloth, wherein low NOx means for reducing the NOx concentration in the exhaust gas to 20 ppm (O ₂ = 0% conversion) or less is provided. A hot air type fiber dryer. 2. The gas burner having an air ratio of 1.3.
The mixing chamber to which the above-mentioned lean air-fuel mixture is supplied has a flame hole plate on the front end face, and the flame hole plate is provided with a plurality of concentric or parallel rows of flame holes, and the corresponding flame holes of adjacent flame hole rows are provided. The hot-air fiber dryer according to claim 1, wherein the flames collide with each other by inclining at least one of the flames. 3. The hot-air fiber dryer according to claim 1, wherein a catalyst device for NOx reduction is interposed in a high-temperature exhaust passage from the gas burner to the drying chamber.