JPH11300929A - Process to cool printing paper and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve cooling and moisture conditioning at a high efficiency, prevention of generation of static electricity, the effective use of a waste heat and prevention of staining by cooling a printing paper through spraying a cold air in a jet fashion. SOLUTION: In a first stage, a nozzle unit 13a is arranged on a front side and a nozzle unit 14a is arranged on a back side, and in a second stage, a nozzle unit 14b is arranged on the back side and a nozzle unit 15a is arranged on the front side. In a third stage, a nozzle unit 15c is arranged on the front side and a nozzle unit 16a is arranged on the back side, and in a fourth stage, a nozzle unit 15b and a nozzle unit 13b are arranged on the front side and a nozzle unit 17a is arranged on the back side. Thus a printing paper is cooled by dividing a cooling process into blocks to enable the stepwise performance of a mostening and cooling process and a temperature/moisture conditioning process. A cold air 25 is supplied to cold air blowing units 13, 14, 15, 16, 17 through blast ducts 21a, 21b, 21c, 21d, 21e, and then is regulated by the blowing units 13, 14, 15, 16, 17 respectively. Further, the cold air 25 is sprayed to the printing paper in a cold air jet fashion through the nozzle units 13a, 13b, 14a, 15a, 15b, 15c, 16a, 17a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for cooling printed paper of an offset rotary printing press.

[0002]

2. Description of the Related Art In an offset rotary printing press, ink on printing paper is dried by a dryer. However, printing paper downstream of the dryer is sent to the next processing step at a high temperature by hot air drying of the surface. Since the machine in the next process becomes high in temperature due to heat transfer from the paper and causes a failure, conventionally, the temperature of about 110 ° C. to 120 ° C.
Cooling the printing paper which is high temperature of ℃.

However, in order to cool the printing paper at approximately 110 ° C. to 120 ° C., the printing paper is rotated around the outer circumference of a plurality of metal rolls through which cooling water flows, and the cooling is conducted by the heat conduction from the roll surface. However, since the cooling efficiency is low and the inside of the printing paper is not sufficiently cooled, there is a problem that the temperature of the printing paper increases again due to the internal heat storage after passing through the cooling roll. Also,
There is a problem that the cooling efficiency is deteriorated due to the accumulation of oxides inside the cooling roll. Further, undeodorized gas is discharged together with the printing paper from the inside of the dryer, and the solvent vapor used for the ink therein is cooled and liquefied and deposited on the roll surface to form dirt on the paper surface, thereby lowering the printing paper quality. There is a problem that causes.

[0004] To solve the above-mentioned problem, a proposal regarding a cooling device which has recently been improved in cooling efficiency is disclosed in Japanese Patent Application Laid-Open No. Hei 8-52857.
No., published in Japanese Patent Application Publication No. The above proposal is described below with reference to FIG. As shown in the figure, the cooling device according to the present invention is provided with a plurality of cooling rolls 54,... That contact the printing paper 51 downstream of the ink dryer 52, and the printing paper 51 is wound around the cooling rolls 54,. , A watering roll 55 that can be attached to and detached from the front and back of the rotated printing paper 51, and a nozzle 56 that sprays cooling water to the watering roll 55 are provided on the plurality of cooling rolls 54, respectively. It is what it was. It should be noted that the cooling roll 54 is supplied with cold water therein so that the printing paper
Both sides are cooled.

In the above proposal, the cooling efficiency is improved by simultaneous cooling of both sides of the printing paper. The cooling method is based on the conventional low-efficiency heat conduction through the adjacent members, and the method is very important. However, the above-mentioned problems are not included in the system, and the above-mentioned problems are incorporated therein.

[0006]

In order to solve the above-mentioned problems, the amount of heat for cooling the printing paper to room temperature is approximately 5%.
Approximately 10,000 kcal / h is required, and there is a difference depending on the thickness of the printing paper and the like. For this purpose, a method capable of cooling in a stepwise manner is required, and instead of the conventional heat conducting means for successively transmitting heat through adjacent portions, a direct connection between the printing paper and the heat medium flowing in contact with the printing paper is required. It is necessary to enable efficient cooling by the heat transfer means. In addition, as a cold heat source,
It is necessary to make effective use of the waste heat discharged from the dryer of the rotary press. When a fluid is used as the cooling medium as described above, it is necessary to suppress the contamination by collecting paper powder and a solvent mixed in the fluid during the cooling process. Further, the printing paper downstream of the dryer of the rotary printing press is evaporated by a dryer, and is reduced to about 1.5% or less (about 5 to 8% at room temperature). It is necessary to control the humidity through the humidification to return the water content to a normal temperature as much as possible.

The present invention provides a method and an apparatus for cooling a printing paper satisfying the above-described high-efficiency cooling means, humidity control means, static electricity generation preventing means, effective use of waste heat to a cold heat source, and pollution prevention means. It is the purpose.

[0008]

Therefore, a printing paper cooling method according to the present invention is characterized in that, in a method of cooling printing paper downstream of an ink dryer of an offset rotary printing press, the printing paper is cooled by jetting of cool air. And

With the above construction, the printing paper passes through adjacent portions from the metal surface of the conventional roll to the inner surface of the roll, from the inner surface of the roll to the cold water inside, by rotating between a plurality of rolls of the conventional printing paper. In place of the heat transfer means that transfers the heat of the printhead, use an efficient heat transfer means that exchanges heat with the moving fluid that flows in contact with the print surface. The flow of the cooling air as the cooling medium is changed from a laminar flow to an unstable turbulent flow, and turbulent diffusion of enthalpy, a physical quantity, is caused to significantly improve the heat transfer coefficient.

[0010] Therefore, the cool air is caused to impinge on the heat transfer surface in the form of a jet to form an impinging jet, a turbulent flow is formed in the wall jet region on the heat transfer surface, and the adjacent impinging jets are separated from each other at the stagnation point. Later, in the wall jet region, a collision of the opposing jets is caused to enable efficient external diffusion of heat.

[0011] Further, the blowing of the cold air jet according to the first aspect is performed from both sides of the printing paper.

According to the above-described structure, since the cool air jet is blown from both sides of the printing paper, the reaction forces of the collision jet generated on the heat transfer surface of the printing paper cancel each other out, and wrinkles are generated on the printing paper. It is designed to prevent the occurrence of distortion that causes the problem. Cooling is performed from both sides, which is more efficient than conventional one-side alternate cooling using a cooling roll.

[0013] A humidified cool air is used as the cool air according to the first and second aspects.

[0014] As described above, since the cold air pre-humidified is used, a suitable amount of water is gradually given to the printing paper which is extremely dried by a dryer to a water content of about 1% in a cooling process. This eliminates the need for a special humidity control device.

Further, it is effective for improving the cooling efficiency due to latent heat of evaporation of minute water contained in the cold air, especially for cooling the printing paper in a high temperature state immediately after drying.

Further, by giving an appropriate humidity in the process of cooling the printing paper as described above, it is possible to prevent the generation of static electricity and eliminate the trouble of the work due to the charging in the post-process after the cooling process.

Further, the cooling air jet spraying according to the first and second aspects is characterized in that the temperature and humidity can be adjusted step by step for each block.

By dividing the cooling area for each block, in the cooling area near the last stage of the printing paper which needs appropriate temperature and humidity control, the blowing speed is temporarily reduced and the humidification is moderately adjusted. Operation can be enabled.

Further, the cold air according to the first aspect is characterized in that cold water obtained by waste heat of the dryer is used as a cold heat source.

According to the above configuration, the cold heat source of the cold air for cooling includes:
Cold water of about 5 ° C. to 7 ° C. obtained through an absorption refrigerator using waste heat of a dryer is used to save energy.

Further, the humidifying water of the humidified cold air described in claim 2 is recyclable.

With the above arrangement, the humidified air is brought into direct contact with cold water, so that the contaminants contained in the humidified air are discharged to the outside as concentrated sewage by freeze separation and recycled as pure ice water. It is. In particular, when the humidified air is reflux cold air, paper dust and solvent contained in the reflux cold air can be removed, and a special device for removing these contaminants can be eliminated.

Next, the printing paper cooling apparatus of the present invention is a printing paper cooling apparatus after drying an ink of an offset rotary printing press, which comprises a cooling unit for blowing a cool air jet, a cooling heat exchange unit,
And a humidifying section for humidification.

With the above-described structure, the printing paper after leaving the dryer is introduced into a cooling unit, which is formed by a plurality of cooling blocks, and is subjected to temperature and humidity control. The cold air is configured such that the air to be humidified is brought into direct contact with water in a humidifying humidity control section, and then cold is provided in a cold heat exchange section so as to be sent out as wet cold air. Therefore, the cold air blown to the printing paper is introduced into the cooling unit in a state where contaminants are removed and is appropriately humidified, and does not contaminate the printing paper.

A cold air jet spraying unit according to a seventh aspect of the present invention has a configuration in which a double-sided simultaneous spraying nozzle group capable of stepwise temperature and humidity control, a suction section for circulating and returning the blown cold air, and a suction section for external discharge are provided. It is characterized by having done.

With the above arrangement, the cooling unit is constituted by a group of double-sided spray nozzles composed of a plurality of blocks. Impingement jets are formed on both sides of the printing paper as the heat transfer surface, and turbulence is formed in the wall jet region to form an adjacent impingement jet. Efficient external diffusion is achieved by oncoming collisions, enabling highly efficient heat transfer. And place a suction pipe in a part between each nozzle,
The cold air collected through the pipe is introduced into the humidifying / humidifying unit and the cold / heat exchanging unit that performs cold / hot heat transfer through the circulation reflux path. A part of the cool air is discharged to the outside so that fresh air can be supplied as needed.

Further, it is preferable that the cool air jet blowing unit according to the present invention is provided with a tension adjusting unit for printing paper passing through the unit.

Further, the cold heat exchange section according to claim 7 is characterized by being constituted by a waste heat utilization system.

According to the above configuration, the cold air is subjected to heat exchange by the cold heat exchange section to obtain cold air at a required temperature. The cold water used for the cold heat exchange utilizes waste heat of a dryer. It is intended to be useful for energy saving. For example, if an absorption refrigerator is used, 100
Cold water of about 5 ° C to 7 ° C can be obtained by waste heat of about 0 ° C.

Further, the humidifying humidity control unit according to claim 7 is characterized in that the humidifying water can be recycled by freeze separation.

According to the above configuration, since the humidifying and humidifying unit for humidifying the cold air is configured to humidify by passing the humidified air in the bubbling form in the cold water, it is included in the humidified air composed of the recirculated cold air or the newly supplied air. Contaminants such as paper dust and solvents are foamed and separated into cold water, and the cold water is freeze-separated to concentrate and remove the cold water containing the contaminants without using a filter. And the molten water thereof is recycled to the cold water for humidification.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent. FIG.
FIG. 2 is a system diagram showing a schematic configuration of a printing paper cooling device of the present invention. FIG. 2 is a diagram showing a structure of a nozzle unit for blowing a cool air jet of the cooling unit of FIG. It is a figure which shows one Example, (b) is a figure which shows another Example, (c) is a figure which shows the structure of a nozzle unit when a cool air jet is not recirculated. FIG. 3 is FIG.
It is a figure which shows one Example of the suction pipe of FIG.

As shown in FIG. 1, the printing paper cooling apparatus of the present invention comprises a cooling unit 12, a cooling / heat exchanging section 19, a humidifying / humidifying section 18, a ventilation duct 21, a return duct 20, and a connecting pipe 20g. And a configuration including The cooling unit 12 includes cold air blowing units 13, 14, 15, 16, 1
7 are provided, and the nozzle units 13a, 13b, 14a, 14b, 15a, 1
5b, 15c, 16a, and 17a are provided separately or collectively, and the nozzle units are appropriately arranged on the front and back of the printing paper and combined so as to enable simultaneous stepwise back and front cooling. In the first stage, the nozzle unit 13a is arranged on the front side and 14a
On the back side, and in the second stage, the nozzle unit 14b
Are arranged on the back side, and 15a is arranged on the front side. In the third stage, the nozzle unit 15c is arranged on the front side, and 16a is arranged on the back side. In the fourth stage, the nozzle units 15b and 13b are arranged on the front side. The cooling of the printing paper is divided for each block so that the humidification cooling and the temperature and humidity control can be performed stepwise.

The cold air blowing units 13, 14, 1
5, 16, and 17 have ventilation ducts 21 a and 21, respectively.
cool air is supplied through b, 21c, 21d, 21e,
The nozzle units 13a, 13b, 14a, 14b, 15a, 15
Cool air 25 is blown to the printing paper 10 as a cool air jet through b, 15c, 16a, and 17a.

As shown in the cross-sectional views of the cool air blowing unit 13 shown in FIGS. 2A, 2B and 2C, the blown cool air jet collides with the printing paper and becomes an impinging jet 25a to form the printing paper 10. The diffused cold air spreads above
As shown in (a) and (b), it is collected through the suction pipe 13d, is returned to the humidifying / humidifying unit 18 and the cold / heat exchanging unit 19 by the return duct 20a, the connecting pipe 20g, and the fan 18b, is humidified and cooled, and is blown. A return circulation path is formed via the duct 21a to return to the cool air blowing unit 13.

The above-mentioned recirculation circuit is also formed for the cool air blowing units 14, 15, 16, 17 as follows. That is, the cool air blowing unit 14; the nozzle units 14a, 1
4b → suction pipe 14d, 14d → return duct 2
0b → connecting pipe 20g → fan 18b → humidifying / humidifying unit 18 →
Cooling / heat exchanging section 19 → blower duct 21b. Cold air blowing unit 15; nozzle units 15a, 1
5b, 15c → suction pipe 15d, 15d, 15
d → reflux duct 20c → connecting pipe 20g → fan 18b →
Humidifying and humidifying section 18 → cooling and heat exchanging section 19 → blowing duct 21c. Nozzle unit 16a → suction pipe 16d → reflux duct 20d → connecting pipe 20
g → fan 18b → humidifying / humidifying unit 18 → cooling / heat exchanging unit 19 →
Air blow duct 21d. Cold air blowing unit 17; nozzle unit 17a → suction pipe 17d → reflux duct 20e → connecting pipe 20
g → fan 18b → humidifying / humidifying unit 18 → cooling / heat exchanging unit 19 →
Ventilation duct 21e.

Then, as described above, the nozzle units are combined and opposed to both the front and back sides of the printing paper 10 at each cooling stage, and as shown in FIGS. 2 (a), (b) and (c). Nozzle core, nozzle pitch L, printing paper 1
The gap S between the nozzle slit 24a and the nozzle outlet slit 24a is made the same, and the reaction forces received by the printing paper 10 during the formation of the impinging jet are canceled each other to cancel the distortion applied to the printing paper, thereby preventing the occurrence of wrinkles and the like. I have to do it. The nozzle unit is constituted by a plurality of slit groups perpendicular to the flow of the printing paper, and forms a two-dimensional jet on the heat transfer surface facing the cool air jet through the slit to form a two-dimensional jet perpendicular to the heat transfer surface. After the collision, the jet is separated to the left and right from the stagnation point at the center of the collision, and the separated jet forms a two-dimensional turbulent wall jet downstream of the jet to enable highly efficient turbulent heat transfer.

As shown in FIGS. 2A and 2B,
The impinging jet 25a sprayed on the printing paper 10 with the cool air 25 as a jet to cool the printing paper is collected by the suction pipe 13d. However, when the suction pipe is too close to the printing paper, the two-dimensional jet of the jet is generated. Since there is a problem that a part of the nozzle is sucked before colliding with the printing paper, the shape of the nozzle base may be a deeply cut mountain shape shown in FIG. 2A, or a square shape shown in FIG. The degree of freedom in setting the position of the suction pipe may be increased.

When the heat load is large, it may be possible to reduce the energy consumption by discharging the gas into the atmosphere without performing the recovery and reflux by the suction pipe as described above. In such a case, FIG. As shown in c), the horizontal drawing area is increased, the inclination of the chevron is reduced, the wind speed of the discharge flow 27 flowing sideways is reduced, and the heat transfer characteristics of the cool air jet are collected by the discharge fan 27a. It is configured to release it to the atmosphere without dropping it. In addition,
The supply air 26 is, as shown in FIG.
The air is sucked and humidified from the atmosphere by the fan 18b, and is further cooled through the cold heat exchange section 19 to be cooled and blown by the blower duct 21a and the blower ducts 21b and 21c (not shown).
The cool air blowing unit 13 and the cold air blowing units 14, 15, 16, and 1 (not shown) are provided by 21 d and 21 e.
7 is introduced.

Since all of the cold air blown out from the nozzle unit cannot be sucked by the suction pipe, another suction pipe 20f is provided at several places in the apparatus to collect the cold air directed to both sides of the nozzle. The nozzle shape was such that the wind speed was 25 m / s, the nozzle pitch L was 80 mm, and the slit width was 2 mm. If the blower duct that can rectify the cool air to be supplied is used by the blower unit and the appropriate arrangement position and various dimensional values of the suction pipe that do not keep the flow of the cool air blown to the printing paper are set, A thermal property value of 200 Kcal / m ² ° C can be predicted.

FIG. 3 shows a schematic structure of the suction pipe according to an embodiment. As shown in the figure, it is preferable to use a pipe having a diameter D of 30 mm or more and to provide suction holes of about D / 5 at a pitch of about D / 3 in a straight line.

At the inlet and outlet of the cooling unit 12, it is necessary to return the printing paper expanded in the dryer to a normal temperature state by contraction of the cooling unit by humidification and cooling, and this is accompanied by adjustment of the paper feeding speed. Therefore, it is desirable to provide a tension cut.

The humidifying humidity controller 18 includes a return duct 20
And the humidification of the recirculating cool air from the connecting pipe 20g and the make-up air 26, and the fan 1 is provided in the cold water tank 18a.
8b, the paper powder and the solvent contained in the refluxing cold air and the contaminants in the makeup air are separated into the cold water through bubbling and humidified by direct contact. The cold water containing the contaminants is purified by freezing the pure water with ice crystals via a separately provided freeze separation 18c and separated, and the melted water is recycled to the cold water tank 18a. The concentrated sewage is discarded externally, and the solvent and paper powder can be treated without providing a special filter.

The cold heat exchange section 19 is configured to obtain cold air through a heat exchanger 19a using the humidified air as a medium of cold water, and the cold water is supplied to an absorption refrigerator as a waste heat utilizing system. Use from about 7 ° C to 10 ° C from waste heat of dryer
Energy saving is achieved by obtaining cold water of ℃.

[0045]

The printing paper cooling device according to the present invention has the following effects. 1. High-efficiency cooling of printing paper is enabled by spray cooling of a cool air jet. 2. By humidifying and cooling, the moisture content of about 3% immediately after the dryer can be adjusted to about 8% of a normal state, and at the same time, the generation of static electricity can be prevented, and the cause of work congestion in the post-process can be eliminated. 3. By stepwise cooling for each block, the amount of humidity control, the temperature of the cold air, and the like can be arbitrarily reduced, and the best temperature control and humidity control can be achieved in the final stage. 4. In the humidifying / humidifying section, contaminants such as paper dust and solvent contained in the reflux cold air can be eliminated without providing a special filter. 5. Energy saving of the printing system can be achieved by using a waste heat utilization system as a cold heat source.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a schematic configuration of a printing paper cooling device of the present invention.

FIGS. 2A and 2B are diagrams showing a structure of a nozzle unit of a cool air jet of the cooling unit of FIG. 1; FIG. 2A is a diagram showing one embodiment of a reflux circulation nozzle unit; FIG. 2B is a diagram showing another embodiment; (C) is a diagram showing the structure of the nozzle unit when the cool air jet is not recirculated.

FIG. 3 is a view showing one embodiment of a suction pipe of FIG. 2;

FIG. 4 is a diagram showing an example in which the cooling efficiency of a conventional printing paper cooling machine is improved.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Printing paper 12 Cooling unit 13, 14, 15, 16, 17 Cold air blowing unit 13a, 13b, 14a, 14b, 15a, 15b, 1
5c, 16a, 17a Nozzle unit 13d, 14d, 15d, 16d, 17d Suction pipe 18 Humidifier for humidification 19 Cooling heat exchanger 20 Reflux duct 20g Connecting pipe 20a, 20b, 20c, 20d, 20e, 20f Reflux duct 21a, 21b , 21c, 21d, 21e Ventilation duct 25 Cool air 26 Supply air 27 Discharge flow

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Yoshida 2-3-1, Botan, Koto-ku, Tokyo Inside Maekawa Corporation

Claims (10)

[Claims] 1. A method for cooling printing paper, wherein cooling air is blown in a jet stream in cooling the printing paper downstream of an ink dryer of an offset rotary printing press. 2. The method for cooling printing paper according to claim 1, wherein said jetting of said cool air is performed from both sides of said printing paper. 3. The method for cooling printing paper according to claim 1, wherein the cool air is humidified cool air. 4. The printing paper cooling method according to claim 1, wherein the cooling air is jetted in such a manner that temperature and humidity can be adjusted stepwise for each block. 5. The method for cooling printing paper according to claim 1, wherein the cold air uses cold water obtained by waste heat of the dryer as a cold heat source. 6. The method for cooling printing paper according to claim 2, wherein the humidification water of the humidification cool air is recyclable by removing contaminants by freeze separation. 7. A cooling device for a printing paper downstream of an ink drying device of an offset rotary printing press, wherein the cooling device includes a cool air jet spraying cooling unit, a cool air heat exchange unit, and a humidifying humidity control unit. Printing paper cooling device. 8. A double-sided simultaneous spray nozzle group that enables stepwise temperature and humidity control, wherein the cool air jet spray unit includes:
The printing paper cooling device according to claim 7, wherein a suction unit for circulating and returning the blown cool air and a suction unit for external discharge are provided. 9. The printing paper cooling device according to claim 7, wherein the cold heat exchanging unit is constituted by a waste heat utilization system. 10. The cooling device for printing paper according to claim 7, wherein the humidifying section is configured to be able to recycle humidifying water by freeze separation.