Gravure system utilizing waste heat

Abstract

The invention relates to the technical field of gravure, in particular to a gravure system utilizing waste heat. The system comprises an air compressor, a drying oven, an RTO device and an air conditioning unit, the first heat exchanger is used for carrying out heat exchange on waste heat of the air compressor and a water medium, and the second heat exchanger is used for carrying out heat exchange on hot smoke generated by the RTO device and an oil medium; the air conditioning tail end of the air conditioning unit is communicated with the first heat exchanger through a water medium circulating pipeline, the drying oven is communicated with the second heat exchanger through an oil medium circulating pipeline, and a third heat exchanger used for conducting heat exchange on water media and oil media is arranged between the water medium circulating pipeline and the oil medium discharging-in pipe. In the application, the RTO waste heat is provided for the drying oven after heat exchange, so that the temperature provided for the drying oven by the RTO waste heat is appropriate, and meanwhile, the part, exchanged by the water medium, in the RTO waste heat and the waste heat of the air compressor are provided for the air conditioner terminal together, so that the RTO waste heat is fully utilized, and the energy consumption of active heat supply of the air conditioner terminal is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of gravure printing, and in particular to a gravure printing system utilizing waste heat. Background Art

[0002] Gravure printing is a printing method that scrapes off the ink on the printing plate except for the image and text, and then applies appropriate pressure between the printing plate and the printed object through the embossing rubber roller to squeeze the ink from the concave surface onto the printed object. This printing method makes the printed product have the advantages of excellent layering performance, correspondence with various substrates, seamless image printing and good printing quality stability.

[0003] In the gravure printing process, many devices will generate a lot of waste heat during operation, such as air compressors, which mainly provide power for other pneumatic control components and generate a lot of waste heat during operation. Another example is the RTO device, which is mainly used to burn the waste gas generated by printing at high temperature and then discharge it into the air, in which the flue gas with waste heat will be discharged into the air.

[0004] At the same time, in the gravure printing process, there are many devices that need heating, such as air-conditioning units, which are mainly used to adjust the temperature in the workshop. Generally speaking, the temperature of the gravure printing workshop should be kept between 19℃ and 25℃. This range is determined according to the characteristics of the ink and the requirements of the printing process. Specifically, the viscosity of water-based gravure ink is easily affected by the external environment. Too high temperature will cause the amine substances in the ink to evaporate faster, affecting the printing effect; while too low temperature may affect the fluidity of the ink, which is also not conducive to printing; for the air-conditioning unit, the temperature it needs to reach is relatively low, but the space volume it needs to control the temperature is large, which requires a considerable heat source. Another example is the drying device of the gravure printing equipment, which is mainly used to accelerate the drying speed of the printed product. Normally, the drying temperature of the gravure ink should be controlled within a certain range to ensure that the ink can be fully dried without causing deformation of the printing material or excessive drying of the ink. Specifically, the drying temperature should not exceed 100°C to avoid shrinkage of the printing material, affecting registration, ink clogging, printing spotting and other problems. For the drying device, the temperature it needs to reach is relatively high, which also requires a considerable heat source.

[0005] If the waste heat generated by the device can be used in the device that needs heating, the waste of thermal energy resources can be significantly reduced. In the prior art, there are technologies that utilize the waste heat of air compressors and RTO waste heat respectively. For example, the patent document with publication number CN206681949U discloses an air compressor waste heat recovery device, which utilizes the waste heat of the air compressor in the air conditioning heating pipeline; the patent document with publication number CN216183798U discloses an RTO waste heat utilization system for a printing device, which utilizes the RTO waste heat in a drying device. Among them, for the drying device, the waste heat temperature of the RTO device is also relatively high in some cases, so in the patent document CN216183798U, the high-temperature exhaust gas of the RTO is mixed with fresh air and then sent to the printing device, which not only requires the installation of a device for introducing fresh air, but also actually wastes the waste heat of the RTO to a certain extent, and does not fully utilize the waste heat of the RTO. Summary of the invention

[0006] The present invention aims to solve the above-mentioned problem and provide a gravure printing system which can fully utilize the waste heat.

[0007] The technical solution to the problem of the present invention is to provide a gravure printing system utilizing waste heat, comprising a gravure printing device arranged in a workshop, the gravure printing device comprising an air compressor and an oven; an RTO device for treating the gas discharged by the gravure printing device, and an air conditioning unit for adjusting the temperature in the workshop; a first heat exchanger for heat exchanging the waste heat of the air compressor with water medium, and a second heat exchanger for heat exchanging the hot flue gas generated by the RTO device with oil medium; the air conditioning terminal of the air conditioning unit is connected to the first heat exchanger through a water medium circulation pipeline, and the water medium circulation pipeline comprises a water medium discharge pipe for sending water medium from the first heat exchanger to the air conditioning terminal, and a water medium discharge pipe for sending water medium from the air conditioning terminal back to the first heat exchanger; The oven is connected to the second heat exchanger through an oil medium circulation pipeline, and the oil medium circulation pipeline includes an oil medium discharge pipe for conveying the oil medium from the second heat exchanger into the oven, and an oil medium discharge pipe for conveying the oil medium from the oven back to the second heat exchanger; a third heat exchanger for heat exchange between water medium and oil medium is provided between the water medium circulation pipeline and the oil medium discharge pipe.

[0008] As a preferred embodiment of the present invention, the gravure printing equipment also includes a boiler for supplying heat to the oven, and the boiler is connected to the part of the oil medium discharge pipe located between the oven and the third heat exchanger through a branch circulation pipe, and the branch circulation pipe includes a branch discharge pipe for conveying the oil medium from the oil medium discharge pipe into the boiler, and a branch discharge pipe for conveying the oil medium from the boiler back to the oil medium discharge pipe.

[0009] As a preferred embodiment of the present invention, the boiler includes an air inlet pipe and an air outlet pipe, and a fourth heat exchanger for performing heat exchange between the air outlet pipe and the air inlet pipe.

[0010] As a preferred embodiment of the present invention, the water medium circulation pipeline includes a first heat exchange part arranged in the third heat exchanger, and a second heat exchange part arranged in the fourth heat exchanger, and the second heat exchange part is arranged upstream of the first heat exchange part along the flow direction of the water medium.

[0011] As a preferred embodiment of the present invention, the water medium discharge pipe is provided with a first water tank; the water medium discharge pipe is provided with a second water tank, and the second water tank is provided with a water replenishment port.

[0012] As a preferred embodiment of the present invention, the second water tank is connected to the first water tank.

[0013] As a preferred embodiment of the present invention, the air conditioning unit includes an air outlet duct for discharging air in a workshop building, and a water curtain is provided in the air outlet duct; a water inlet of the water curtain is connected to the first water tank.

[0014] As a preferred embodiment of the present invention, a humidifier is provided in the oven; the outlet of the air outlet pipe includes a drainage portion for discharging water, and the drainage portion is connected to the humidifier.

[0015] As a preferred embodiment of the present invention, the air outlet pipe includes a horizontally arranged air guide portion and an air outlet portion vertically connected to the air guide portion, and the water curtain is arranged in the air guide portion.

[0016] As a preferred embodiment of the present invention, the air outlet duct includes an outer shell and an inner shell, and an air outlet channel for air outlet and provided with the water curtain is formed between the outer shell and the inner shell; the air-conditioning unit also includes an air inlet duct for introducing fresh air, and the air inlet duct is arranged in the air guide part of the inner shell.

[0017] Beneficial effects of the present invention: 1. In this application, the RTO waste heat is provided to the oven of the gravure printing equipment after heat exchange, so that the temperature provided to the oven is suitable for drying printed materials. Among them, the part of the RTO waste heat replaced by the water medium is provided to the air conditioning terminal together with the air compressor waste heat, which not only fully utilizes the RTO waste heat, but also makes up for the problem of insufficient heat supply to the air conditioning terminal by the air compressor waste heat, and reduces the energy consumption of active heating of the air conditioning terminal. There is no active waste of waste heat in this application, and the waste heat of the air compressor and the RTO waste heat are fully utilized.

[0018] 2. In some embodiments, based on the original boiler device of the gravure printing equipment, the oil medium can be selectively fed into the boiler. When the temperature of the oil medium after heat exchange is lower than the temperature required by the oven, the boiler is turned on and the oil medium fed into the boiler can be heated in the boiler. When the temperature of the oil medium after heat exchange is still higher than the temperature required by the oven, the oil medium fed into the stopped boiler can maintain the temperature in the boiler, so as to reduce the preheating step of the boiler when the boiler needs to be turned on later, thereby reducing energy consumption.

[0019] On this basis, in some embodiments, a fourth heat exchanger is provided on the boiler, and the water medium is controlled to pass through the fourth heat exchanger first and then the third heat exchanger. Then, when the oil medium is lower than the temperature required by the oven after heat exchange, the boiler will be turned on, and the boiler will generate hot exhaust gas to preheat the water medium; after the preheated water medium enters the third heat exchanger, the temperature difference between it and the oil medium becomes smaller, and the heat absorbed by the oil medium is less, so that the temperature of the oil medium after heat exchange at this time increases relative to the temperature of the oil medium in the previous cycle, and is closer to or even suitable for the temperature required by the oven. At this time, the boiler can be turned down or closed to reduce energy consumption.

[0020] 3. In some embodiments, a first water tank is provided so that when the air conditioning terminal and the oven do not need heating, the water medium that absorbs the waste heat of the air compressor and the waste heat of the RTO can be stored in the first water tank for use when the air conditioning terminal and the oven need heating, thereby reducing the loss of waste heat of the air compressor and the RTO.

[0021] 4. In some embodiments, the excess water medium in the first water tank is applied to the air outlet of the air conditioning unit, and the hot water is used to dissolve a small amount of volatile substances in the gas in the air outlet to reduce the emission of odor. On this basis, in some embodiments, the dissolved hot water is applied to the air inlet of the air conditioning unit to preheat the fresh air, further utilizing the excess heat medium and reducing the energy consumption of the air conditioning unit. On this basis, in some embodiments, the dissolved hot water is applied to the oven of the gravure printing equipment to humidify the printed items in the drying process and prevent the printed items from curling, further utilizing the excess heat medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of a gravure printing system embodiment 1 utilizing waste heat; Figure 2 is a schematic diagram of a second embodiment of a gravure printing system utilizing waste heat; Figure 3 is a schematic diagram of the structure of the air inlet duct and the air outlet duct of the air conditioning unit in Example 2; In the figure: an air compressor 11, an oven 12, a boiler 13; an RTO device 2; an air conditioning unit 3, an air conditioning terminal 31, an air guide portion 321, an air outlet portion 322, an outer shell 32a, and an inner shell 32b, an air inlet pipe 33; a first heat exchanger 41, a second heat exchanger 42, a third heat exchanger 43, a fourth heat exchanger 44; a first water tank 51, a second water tank 52. DETAILED DESCRIPTION

[0023] The following are specific implementations of the present invention, and in conjunction with the accompanying drawings, the technical solution of the present invention is further described, but the present invention is not limited to these embodiments.

[0024] Example 1 A gravure printing system that utilizes waste heat, such as Figure 1 As shown, first, it includes gravure printing equipment, which is installed in the workshop and is used for printing. It generally includes a gravure cylinder for printing, a scraper device for scraping off excess ink on the gravure cylinder, an ink tank and an ink supply system for supplying ink to the gravure cylinder, a stamping cylinder for cooperating with the gravure cylinder to achieve ink transfer, and a drying device for accelerating the drying process of ink on printed items; at the same time, most of these devices are powered by an air compressor 11. The air compressor 11 generates heat during operation. The drying device includes an oven 12 for printed items to enter and exit, and a boiler 13 for heating the oven 12. The boiler 13 generates heat by introducing air to burn with natural gas and exchanges the heat with a heat medium. The oven 12 includes an opening and an outlet for the heat medium to enter and exit. When the heat medium flows from its inlet to its outlet in the oven 12, it exchanges heat with the air and printed items in the oven to achieve drying. It is preferred to control the flow direction of the heat medium in the oven 12 to be opposite to the conveying direction of the printed article in the oven 12, so that the temperature of the front part of the oven 12 is relatively low and the temperature of the rear part is relatively high, forming a temperature gradient, so that the heating degree of the printed article gradually increases, ensuring the uniformity of drying of the printed article from the inside to the outside, and avoiding the printed article from curling or cracking due to sudden high heat.

[0025] Secondly, since the volatilization of ink solvents during the printing process will produce waste gas, the gravure printing system also includes an RTO device 2 for treating the gas discharged by the gravure printing equipment. The full name of the RTO device 2 is a regenerative thermal oxidizer, which is an energy-saving and environmentally friendly device for treating medium and low concentration volatile organic waste gas (VOCs). Its working principle is to oxidize the organic waste gas at high temperature (usually ≥760℃) to generate carbon dioxide and water, so as to remove it. The RTO device 2 is heavy and large in size, and can usually only be placed outdoors.

[0026] Finally, the gravure printing system also includes an air conditioning unit 3 for adjusting the temperature in the workshop to ensure the normal operation of the gravure printing equipment. The air conditioning terminal 31 in the air conditioning unit is a device for exchanging heat between air and a refrigeration structure or a heating structure to deliver cold air or hot air into the room. Part of the heating structure will be realized through a coil heat exchanger, and the air is heated by inputting hot heat medium into the coil heat exchanger. After the heat exchange is completed, the cold heat medium is discharged. Therefore, Figure 1 As shown, the air conditioning terminal 31 includes an inlet 311 and an outlet 312 for the entry and exit of heat medium.

[0027] It can be seen that there are both devices with waste heat and devices that need heat supply in the gravure printing system. If the waste heat of the device can be supplied to the heating device, energy consumption can be effectively reduced. Based on the different waste heat temperatures of different devices and the different heat required by different heating devices, this application has made the following design: First, the waste heat of the air compressor 11 is utilized in the air conditioning terminal 31: first, a first heat exchanger 41 is set, and the first heat exchanger 41 is used to exchange the waste heat of the air compressor 11 with the heat medium, wherein the working waste heat temperature of the air compressor 11 is not very high, so the heat medium in the first heat exchanger 41 can be water. Specifically: the oil pipeline of the air compressor 11 and the heat medium pipeline of the first heat exchanger 41 are alternately arranged, and when the hot oil in the air compressor 11 flows in the oil pipeline, the heat will be transferred to the water in the heat medium pipeline, so that the water is heated and the oil is cooled. When the cooled oil returns to the air compressor 11, it can cool the air compressor 11 to a certain extent. Secondly, the obtained hot water is sent to the air-conditioning terminal 31, so a water medium discharge pipe and a water medium discharge pipe are respectively provided at both ends of the heat medium pipeline to form a water medium circulation pipeline together; one end of the water medium discharge pipe is connected to the heat medium outlet of the heat medium pipeline, and the other end is connected to the inlet 311 of the air-conditioning terminal 31, which is used to send the hot water obtained by heat exchange from the first heat exchanger 41 to the air-conditioning terminal 31; after the hot water enters the air-conditioning terminal 31, it can exchange heat with the air to heat the air, and the hot air is sent to the workshop by the air-conditioning terminal 31 to increase the temperature in the workshop; one end of the water medium discharge pipe is connected to the heat medium inlet of the heat medium pipeline, and the other end is connected to the outlet 312 of the air-conditioning terminal 31, which is used to send the cooled water after heat exchange from the air-conditioning terminal 31 back to the first heat exchanger 41.

[0028] Since the ambient temperature suitable for gravure printing is generally between 19°C and 25°C, it is not necessary to increase the temperature in the workshop at any time. When the air-conditioning terminal 31 does not need to work, and the air compressor 11 is still working to generate waste heat, in order to avoid the loss of waste heat generated by the air compressor 11 at this time, in this application, firstly, a first water tank 51 is provided on the water medium discharge pipe, and the first water tank 51 includes a high-temperature inlet and a high-temperature outlet. The water medium discharge pipe is divided into two parts, one part is connected to the heat medium outlet of the first heat exchanger 41 and the high-temperature inlet of the first water tank 51, and the other part is connected to the high-temperature outlet of the first water tank 51 and the inlet 311 of the air-conditioning terminal 31; of course, a water pump and a valve can be set as needed. Then, when the air-conditioning terminal 31 does not need to work, the high-temperature outlet of the first water tank 51 is closed, and the hot water that absorbs the waste heat of the air compressor 11 can enter the first water tank 51 for storage, so as to be directly used when the air-conditioning terminal 31 needs to work.

[0029] At this time, since the air compressor 11 is still working and needs to be cooled, a second water tank 52 is also provided on the water medium discharge pipe. The second water tank 52 includes a low-temperature inlet, a low-temperature outlet, and a liquid replenishing port. The water medium discharge pipe is divided into two parts, one part is connected to the outlet 312 of the air conditioning terminal 31 and the low-temperature inlet of the second water tank 52, and the other part is connected to the low-temperature outlet of the second water tank 52 and the heat medium inlet of the first heat exchanger 41. Of course, a water pump and a valve can also be provided as needed. Then, when the air conditioning terminal 31 does not need to work and the air compressor 11 still needs to be cooled, the water in the second water tank 52 whose temperature is reduced after heat exchange with the air conditioning terminal 31 during heating, and the water replenished by the liquid replenishing port, can ensure the continuous cooling of the air compressor 11.

[0030] If the air compressor 11 continues to work and the air conditioning terminal 31 continues to not provide heat, the hot water in the first water tank 51 may accumulate more and more. Therefore, on the one hand, the first water tank 51 and the second water tank 52 are connected. The position of the connection is very important. Specifically, in this embodiment, the first water tank 51 is provided with a high-temperature balance port, and the high-temperature balance port is located between the high-temperature inlet and the high-temperature outlet in terms of height; similarly, the second water tank 52 is provided with a low-temperature balance port, and the low-temperature balance port is located between the low-temperature inlet and the low-temperature outlet in terms of height; the high-temperature balance port is connected with the low-temperature balance port. Therefore, when the hot water in the first water tank 51 accumulates more and more, it will enter the second water tank 52 after reaching the height of the high-temperature balance port. The excess hot water enters the second water tank 52 and is sprayed and mixed with the cold water inside, and the temperature is reduced. On the other hand, in order to prevent the first water tank 51 and the second water tank 52 from being filled with water, which would increase the pressure in the circulation pipeline and cause damage, a high-temperature overflow port is provided on the first water tank 51 and a low-temperature overflow port is provided on the second water tank 52. Both the high-temperature overflow port and the low-temperature overflow port are arranged at the top of the tank body to discharge excess water.

[0031] Second, the waste heat of the RTO device 2 is applied to the oven 12: first, a second heat exchanger 42 is set, and the second heat exchanger 42 is used to exchange heat between the hot flue gas generated by the RTO device 2 and the liquid heat medium. Since the temperature of the RTO waste heat is relatively high, which may exceed 100°C, the liquid heat medium is oil. Secondly, the second heat exchanger 42 is connected to the oven 12 through an oil medium circulation pipeline. Specifically: using the inlet and outlet of the above-mentioned oven 12, the second heat exchanger 42 includes a shell, and a part of the circulation pipeline is arranged in the shell. The shell is arranged on the flue gas exhaust pipeline of the RTO device 2. When the hot flue gas flows through the inner cavity of the shell, it will contact this part of the circulation pipeline to exchange heat with the oil medium therein and obtain hot oil. At the same time, the oil medium circulation pipeline also includes an oil medium discharge pipe and an oil medium discharge pipe which are respectively connected to the two ends of this part of the pipeline in the shell. The other end of the oil medium discharge pipe is connected to the inlet of the oven 12 and is used to deliver hot oil from the second heat exchanger 42 to the oven 12; the other end of the oil medium discharge pipe is connected to the outlet of the oven 12 and is used to return the oil medium cooled after heat exchange from the oven 12 to the second heat exchanger 42, so as to reheat the RTO exhaust gas on the one hand and cool the RTO exhaust gas on the other hand.

[0032] At the same time, since the temperature range of the hot flue gas of RTO is large, the temperature of the oil medium that absorbs the waste heat of RTO is unstable, and in some cases it may not be enough to provide enough drying heat for the oven 12. Therefore, the original boiler 13 is also introduced into the oil medium circulation pipeline and used as an auxiliary when necessary. Specifically: the boiler 13 is connected to the oil medium discharge pipe through a branch circulation pipeline, and the branch circulation pipeline includes a branch discharge pipe for sending the oil medium from the oil medium discharge pipe to the boiler 13, and a branch discharge pipe for sending the oil medium from the boiler 13 back to the oil medium discharge pipe. In other words, the oil medium can directly enter the oven 12 through the oil medium discharge pipe, or it can first enter the front part of the oil medium discharge pipe, then enter the branch circulation pipeline to flow through the boiler 13, and then enter the rear part of the oil medium discharge pipe before entering the oven 12; therefore, the oil medium discharge pipe should also be provided with a valve for controlling whether the liquid enters the branch circulation pipeline. When the temperature of the oil medium that absorbs the waste heat of RTO is lower than the temperature required for drying the oven 12, the boiler 13 can be turned on, and the oil medium enters the boiler 13 through the branch circulation pipeline to be heated. In some cases, when the temperature of the oil medium that has absorbed the waste heat of RTO is higher than the temperature required for drying in the oven 12, the oil medium can also be sent into the shut down boiler 13 through a branch circulation pipeline. On the one hand, the oil medium temperature can be reduced, and on the other hand, the temperature inside the boiler 13 can be maintained, so as to reduce the boiler preheating step when the boiler 13 needs to be started later, thereby reducing energy consumption.

[0033] Among them, when the boiler 13 needs to be used, fresh air is introduced and burned together with natural gas. The heat generated is exchanged with the oil medium in the branch circulation pipeline, and the exhaust gas is discharged. The exhaust gas also has a certain amount of heat that can be reused. Therefore, in some embodiments, the boiler 13 includes an air inlet pipe for introducing fresh air and an air outlet pipe for discharging exhaust gas, and also includes a fourth heat exchanger 44 for heat exchange between the air inlet pipe and the air outlet pipe. The heat of the exhaust gas is exchanged with the fresh air through the fourth heat exchanger 44. On the one hand, the fresh air is preheated and the energy consumption of the boiler 13 is reduced, and on the other hand, the exhaust gas is cooled. The fourth heat exchanger 44 is set in a similar manner to the second heat exchanger 42. A shell is also set. The shell is set on the exhaust pipe, and a part of the air inlet pipe is set in the shell. When the exhaust gas flows through the inner cavity of the shell, it will contact this part of the air inlet pipe to preheat the fresh air inside it.

[0034] In this embodiment, since the heat medium used is oil medium, in order to ensure the safety of the circulation pipeline, in some embodiments, the discharge pipe is provided with an oil-gas separator, and the oil-gas separator includes an oil-gas inlet connected to the oven 12, an oil outlet connected to the second heat exchanger 42, and an exhaust port. The oil-gas separator can separate impurities and gases in the oil medium, adjust the pressure in the system, reduce the influence of gas on the working characteristics of the pump or the heat medium system, and maintain the cleanliness of the oil medium. The clean oil medium has better fluidity and heat conduction performance, thereby improving the overall efficiency of the heat medium system. Further, it also includes a high-level expansion tank and a low-level storage tank; the oil-gas separator also includes a liquid guide port; the high-level expansion tank includes an air inlet connected to the exhaust port, a high-level liquid inlet connected to the liquid guide port, and also includes an overflow port, a high-level liquid outlet, and a circulation inlet; the low-level storage tank includes a low-level liquid inlet connected to the overflow port and the high-level liquid outlet, and a circulation outlet connected to the circulation inlet; in addition, the low-level storage tank also includes an oil filling port and a waste outlet. The high-position expansion tank and the low-position storage tank connected to the oil-gas separator are commonly used designs in the prior art and will not be described in detail here.

[0035] Third, the waste heat temperature of the RTO device 2 is relatively high, and the waste heat temperature of the air compressor 11 is relatively low, so in some cases, the oil medium circulation process has the problem of too much heat being provided to the oven 12, and the water medium circulation process has the problem of insufficient heat being provided to the air conditioning terminal 31. Therefore, a third heat exchanger 43 for heat exchange between water medium and oil medium is provided between the water medium circulation pipeline and the oil medium discharge pipe, so that the RTO waste heat is provided to the oven 12 of the gravure printing device after heat exchange, so that the temperature provided to the oven 12 is suitable and suitable for drying printed products. Among them, the part of the RTO waste heat exchanged by the water medium is provided to the air conditioning terminal 31 together with the waste heat of the air compressor 11, which not only makes full use of the RTO waste heat, but also makes up for the problem of insufficient heat supply to the air conditioning terminal by the waste heat of the air compressor 11, and reduces the energy consumption of active heating of the air conditioning terminal 31.

[0036] Among them, the third heat exchanger 43 and the oil medium discharge pipe are arranged in the following manner: an oil medium branch is added, one end of the oil medium branch is connected to the oil medium discharge pipe, and the other end is connected to the oil medium discharge pipe after passing through the third heat exchanger 43; and a valve is also included for controlling whether the oil medium enters the oil medium branch.

[0037] The third heat exchanger 43 and the water medium circulation pipeline are arranged in the following manner: a water medium branch can be added as in the arrangement of the oil medium discharge pipe described above, one end of the water medium branch is connected to the water medium discharge pipe, and the other end is connected to the oil medium discharge pipe after passing through the third heat exchanger 43, so that the water medium that has absorbed the waste heat of the air compressor is reheated and then sent to the air conditioning terminal 31. It is also possible to add a first branch and a second branch as in the present embodiment, the two ends of the first branch are respectively connected to the heat medium inlet and the water medium discharge pipe of the third heat exchanger 43; the two ends of the second branch are respectively connected to the heat medium outlet and the water medium discharge pipe of the third heat exchanger 43; therefore, the water medium in the water medium discharge pipe can directly enter the air compressor 11 to utilize the waste heat of the air compressor 11, or can enter the third heat exchanger 43 from the first branch to utilize the waste heat from the RTO device 2, and then return to the water medium discharge pipe through the second branch, and then enter the first water tank 51 for storage or enter the air conditioning terminal 31 again.

[0038] Example 2 This embodiment is basically the same as Embodiment 1, except that: After the third heat exchanger 43 is set, in some cases, after the heat exchange in the third heat exchanger 43, the temperature of the oil medium may drop to a level that is insufficient to provide suitable drying heat for the oven 12, and the boiler 13 needs to be turned on, resulting in increased energy consumption. Therefore, in some embodiments, a fifth heat exchanger is also included for heat exchange between the outlet pipe of the boiler 13 and the water medium, and the water medium is controlled to enter the first water tank 51 after passing through the fifth heat exchanger and the third heat exchanger 43 in sequence. Then, when the oil medium is lower than the temperature required by the oven 12 after heat exchange, the boiler 13 will be turned on, and the boiler 13 will generate hot exhaust gas, thereby preheating the water medium at the fifth heat exchanger; after the preheated water medium enters the third heat exchanger 43, the temperature difference between the oil medium and the preheated water medium becomes smaller, and the heat absorption of the oil medium is less, so that the temperature of the oil medium after heat exchange at this time increases relative to the temperature of the oil medium in the previous cycle, and is closer to or even suitable for the temperature required by the oven 12. At this time, the boiler 13 can be turned down or closed to reduce energy consumption. Among them, the design method of the fifth heat exchanger is not limited. It can be an independent heat exchanger, or, as in the present embodiment, the fifth heat exchanger is directly modified based on the fourth heat exchanger 44. The water medium circulation pipeline includes a first heat exchange part arranged in the third heat exchanger 43, and a second heat exchange part arranged in the fourth heat exchanger 44. Along the flow direction of the water medium, the second heat exchange part is arranged upstream of the first heat exchange part. Specifically: the second heat exchange part is arranged in the shell of the fourth heat exchanger 44. When the exhaust gas flows through the inner cavity of the shell, it will not only contact the air inlet pipe, but also contact the second heat exchange part to preheat the water therein; one end of the second heat exchange part is connected with the outlet of the second water tank 52 through the water inlet pipe, and the other end is connected with the heat medium inlet of the third heat exchanger 43 through the water outlet pipe, and then the heat medium outlet of the third heat exchanger 43 is connected with the inlet of the first water tank 51; based on this, the cold water coming out of the second water tank 52 can first enter the second heat exchange part in the fourth heat exchanger 4, then enter the third heat exchanger 43, then enter the first water tank 51, and then enter the air-conditioning terminal 31.

[0039] In some embodiments, when the hot water in the first water tank 51 accumulates more and more, the excess hot water will enter the second water tank 52 or be discharged from the high-temperature overflow port, and this part of the hot water will be wasted. Therefore, in this embodiment, this part of the hot water is reused.

[0040] like Figure 2 As shown, the first water tank 51 and the second water tank 52 are connected through a medium-temperature heat medium box. Specifically, the high-temperature overflow port, the high-temperature balance port, the low-temperature overflow port, and the low-temperature balance port are respectively connected to the medium-temperature heat medium box through pipes, so that warm water with a moderate temperature obtained by mixing hot water and cold water can be obtained in the medium-temperature heat medium box.

[0041] At the same time, the gravure printing system also includes a humidifying unit for adjusting the humidity in the workshop. Generally, the humidity of the gravure printing workshop should be controlled between 50% and 70%. This range helps to maintain the stability of the plate roller and the good transfer effect of the ink. Too low humidity may cause the plate roller to fall off due to drying, affecting the continuity of the printing process. Therefore, the humidifying unit is also one of the more important devices in the gravure printing system. The humidifying unit includes a humidifying water tank, which generally atomizes the water in the humidifying water tank by ultrasonic wave and then blows it into the air. In this embodiment, the medium-temperature heat medium box is connected to the humidifying water tank to replenish water for the humidifying water tank. Since the supplement is warm water with a certain temperature, this can slightly increase the temperature of the workshop while providing humidity, further fully utilizing the excess heat medium, and reducing the heating energy consumption of the air conditioning unit. Among them, it is preferred to provide an RO filter between the medium-temperature heat medium box and the humidifying water tank, and a water pump that forces warm water to pass through the RO filter can be set as needed to obtain purer water and ensure the safety of humidification.

[0042] In some embodiments, the excess hot water can be further utilized. Figure 2 and Figure 3 As shown, the known air conditioning unit generally also includes an air outlet duct for discharging the air in the workshop and an air inlet duct 23 for introducing fresh air. The gravure ink contains some volatile substances, such as ethanol, ethyl acetate, etc., which will evaporate during the printing process. Although the gravure printing equipment itself has an exhaust device and an exhaust gas treatment device that can treat the gas containing these volatile substances, it is inevitable that some of the gas will escape into the air of the workshop, which makes the exhaust gas in the air outlet duct contain trace volatile substances and have a certain odor. Based on this, in this embodiment, a water curtain is also provided in the air outlet duct, and the water inlet of the water curtain is connected to the first water tank 51, specifically connected to the high-temperature overflow port and the high-level balance port, so that the excess hot water is applied to the gas in the air outlet duct. When the gas containing trace volatile substances passes through the hot water water curtain, based on the principle that it is generally more soluble in hot water, many water-soluble volatile substances can be effectively dissolved and separated from the gas, thereby improving the purity of the exhaust gas.

[0043] In order to prevent the water from the water curtain from flowing back into the air conditioning unit from the air outlet pipe, Figure 3 As shown, the air outlet pipe includes a horizontally arranged air guide portion 321, and a water curtain is arranged in the air guide portion 321 to spray hot water from top to bottom. Preferably, the bottom of the air guide portion 321 is arranged as an inclined slope to facilitate the discharge of water.

[0044] Furthermore, hot water in which trace volatile substances are dissolved can also be used. Figure 3As shown, the structure of the air outlet pipe is adjusted. First, from the appearance, the air outlet pipe includes the above-mentioned horizontally arranged air guide portion 321, and also includes an air outlet portion 322 vertically connected to the air guide portion 321; secondly, from the internal and external structure, the air outlet pipe includes an outer shell 32a and an inner shell 32b, and an air outlet channel for air outlet and provided with a water curtain is formed between the outer shell 32a and the inner shell 32b. That is to say, the outer shell 32a is composed of a part of a tubular structure and an annular disk arranged at the port of the tubular structure, and the inner shell 32b is composed of a part of a tubular structure with a smaller outer diameter and an annular disk arranged at the port of the tubular structure. The air outlet pipe of this embodiment can be obtained by inserting the tubular structure of the inner shell 32b into the tubular structure of the outer shell 32a and fixing it. At this time, a circle of annular openings is formed between the free end of the annular disk of the inner shell 32b and the free end of the annular disk of the outer shell 32a as an air outlet. If necessary, this opening can also be closed by an annular plate, and then a hole is opened on the annular plate to serve as an air outlet. The water outlet of the water curtain is arranged at the inner top of the air guide portion 321, and the water coming out of the water curtain will fall on the outer wall of the tubular structure of the inner shell 32b, and then fall on the inner wall of the tubular structure of the outer shell 32a.

[0045] Based on this, on the one hand, the horizontal air inlet pipe 33 is arranged in the tubular structure of the inner shell 32b, so that when the water with a certain temperature coming out of the water curtain falls on the outer wall of the tubular structure of the inner shell 32b, the fresh air in the water inlet pipe 33 can be preheated. When the air conditioning terminal 31 needs to be heated, the energy consumption of the air conditioning terminal 31 can be reduced.

[0046] On the other hand, the bottom surface of the housing 32a can be set to a horizontal downwardly inclined structure to facilitate the discharge of water. Therefore, in the downward portion of the air outlet of the air outlet pipe, there is a drainage part for water discharge, and this part of water can be discharged directly; further, in some embodiments, a humidifier is provided in the oven 12. The function of the humidifier in the oven is to prevent problems such as curling during the drying process of printed items. By connecting the drainage part with the humidifier in the oven, this part of water can be reused. Since volatile gases are generated in the oven, water containing trace amounts of volatile gases is used for humidification therein and will not have an adverse effect. Among them, the humidifier includes a water pipe arranged in the oven 12, one end of the water pipe is an inlet connected to the first water tank 51, and the other end is a closed end, or an outlet is provided to connect to the first water tank 51 to form a water cycle, and a plurality of spray holes are provided on the water pipe body along its length direction for spraying water mist. In conjunction with the above-mentioned technology of controlling the flow direction of the hot oil in the oven 12 in the opposite direction of the conveying direction of the printed articles in the oven 12, the direction from the inlet of the water pipe to the closed end is also controlled in the opposite direction of the conveying direction of the printed articles in the oven 12, so that the temperature of the front part of the oven 12 is relatively low and the temperature of the rear part is relatively high, forming a temperature gradient and improving the drying uniformity of the printed articles.

[0047] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A gravure printing system utilizing waste heat, characterized in that: The invention comprises a gravure printing device arranged in a workshop, wherein the gravure printing device comprises an air compressor (11) and a drying oven (12); It also includes an RTO device (2) for treating the gas discharged by the gravure printing equipment, and an air conditioning unit (3) for regulating the temperature in the workshop; It also includes a first heat exchanger (41) for performing heat exchange between the waste heat of the air compressor (11) and water medium, and a second heat exchanger (42) for performing heat exchange between the hot flue gas generated by the RTO device (2) and oil medium; The air conditioning terminal (31) of the air conditioning unit (3) is connected to the first heat exchanger (41) via a water medium circulation pipeline, wherein the water medium circulation pipeline comprises a water medium discharge pipe for conveying water medium from the first heat exchanger (41) to the air conditioning terminal, and a water medium discharge pipe for conveying water medium from the air conditioning terminal back to the first heat exchanger (41); The oven (12) and the second heat exchanger (42) are connected via an oil medium circulation pipeline, wherein the oil medium circulation pipeline comprises an oil medium discharge pipe for conveying the oil medium from the second heat exchanger (42) into the oven (12), and an oil medium discharge pipe for conveying the oil medium from the oven (12) back to the second heat exchanger (42); A third heat exchanger (43) for performing heat exchange between the water medium and the oil medium is provided between the water medium circulation pipeline and the oil medium discharge pipe.

2. A gravure printing system utilizing waste heat according to claim 1, characterized in that: The gravure printing device further comprises a boiler (13) for supplying heat to the oven (12); the boiler (13) is connected to a portion of the oil medium discharge pipe located between the oven (12) and the third heat exchanger (43) via a branch circulation pipeline; the branch circulation pipeline comprises a branch discharge pipe for conveying the oil medium from the oil medium discharge pipe into the boiler (13), and a branch discharge pipe for conveying the oil medium from the boiler (13) back to the oil medium discharge pipe.

3. A gravure printing system utilizing waste heat according to claim 2, characterized in that: The boiler (13) comprises an air inlet pipe and an air outlet pipe, and a fourth heat exchanger (44) for performing heat exchange between the air outlet pipe and the air inlet pipe.

4. The gravure printing system using waste heat according to claim 3, characterized in that: The water medium circulation pipeline comprises a first heat exchange portion arranged in the third heat exchanger (43), and a second heat exchange portion arranged in the fourth heat exchanger (44), and the second heat exchange portion is arranged upstream of the first heat exchange portion along the flow direction of the water medium.

5. The gravure printing system utilizing waste heat according to claim 1, characterized in that: The water medium discharge pipe is provided with a first water tank (51); the water medium discharge pipe is provided with a second water tank (52), and the second water tank (52) is provided with a water replenishment port.

6. The gravure printing system using waste heat according to claim 5, characterized in that: The second water tank (52) is in communication with the first water tank (51).

7. The gravure printing system utilizing waste heat according to claim 5, characterized in that: The air conditioning unit comprises an air outlet duct for discharging air in a workshop, and a water curtain is arranged in the air outlet duct; the water inlet of the water curtain is connected to the first water tank (51).

8. The gravure printing system utilizing waste heat according to claim 7, characterized in that: A humidifier is provided in the oven (12); the outlet of the air outlet pipe comprises a drainage portion for discharging water, and the drainage portion is connected to the humidifier.

9. The gravure printing system using waste heat according to claim 7, characterized in that: The air outlet pipe comprises a horizontally arranged air guide portion (321) and an air outlet portion (322) vertically connected to the air guide portion (321), and the water curtain is arranged in the air guide portion (321).

10. The gravure printing system utilizing waste heat according to claim 9, characterized in that: The air outlet pipe comprises an outer shell (32a) and an inner shell (32b); an air outlet passage for air outlet and provided with the water curtain is formed between the outer shell (32a) and the inner shell (32b); the air conditioning unit further comprises an air inlet pipe (33) for introducing fresh air; the air inlet pipe (33) is arranged in the air guide portion (321) of the inner shell (32b).

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