WO2024141504A2 - Four de séchage à l'air avec économie d'énergie - Google Patents

Four de séchage à l'air avec économie d'énergie Download PDF

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Publication number
WO2024141504A2
WO2024141504A2 PCT/EP2023/087727 EP2023087727W WO2024141504A2 WO 2024141504 A2 WO2024141504 A2 WO 2024141504A2 EP 2023087727 W EP2023087727 W EP 2023087727W WO 2024141504 A2 WO2024141504 A2 WO 2024141504A2
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WO
WIPO (PCT)
Prior art keywords
drying
fluid
oven
heat pump
air
Prior art date
Application number
PCT/EP2023/087727
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English (en)
Other versions
WO2024141504A3 (fr
Inventor
Luigi Franzoni
Original Assignee
Cefla Societa' Cooperativa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cefla Societa' Cooperativa filed Critical Cefla Societa' Cooperativa
Publication of WO2024141504A2 publication Critical patent/WO2024141504A2/fr
Publication of WO2024141504A3 publication Critical patent/WO2024141504A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
    • F27B9/10—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated heated by hot air or gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases

Definitions

  • the drying fluid is mainly air, but also other gases might be used, e.g. inert gases.
  • said pieces can reach lengths of over 6 metres, with a typical width of 1300-1600 mm and a thickness of 5-300 mm.
  • the drying process is a polluting process, in that the organic solvents contained in paints are evaporated through heat, and organic molecules may be dispersed in the environment.
  • the class of the Volatile Organic Compounds (VOCs) comprises different chemical compounds whose molecules contain different functional groups: such compounds overall have different physical and chemical behaviours, but share a high volatility, that is characteristic e.g. of the common organic solvents, like paint thinners or alcohols. If the solvent is water, often substances are added in order to increase its evaporation, which in turn can release VOCs.
  • Heat pumps are known in the art: a heat pump is a thermal device that can extract and transfer thermal energy using different forms of energy, generally mechanical energy.
  • the working of a heat pump is the following: the compressor of a heat pump suctions a gaseous refrigerant compressing it in the high-pressure area of the circuit.
  • the compressed gaseous refrigerant that is heated through the increase in pressure, is pushed into a first heat exchanger (condenser), wherein it releases heat to the environment to be heated, environment that has a temperature lower than that of the gaseous refrigerant; said gaseous refrigerant cools down, until it condenses in liquid form.
  • the liquid is pushed through a reversing valve that separates the high-pressure portion from the low-pressure portion of the heat pump circuit.
  • the term efficiency is avoided, as by definition it is always lower than 1.
  • the term performance is used, which is expressed as a Coefficient Of Performance (COP), which is the ratio between supplied energy (provided heat) and consumed energy (generally electric energy, required by the compressor), usually indicated in technical physics as coefficient of effectiveness.
  • COP Coefficient Of Performance
  • a value of 3 for the COP means that for each kWh of consumed electric energy the heat pump transfers 3 kWh of thermal energy from or to the interested source.
  • drying When drying, higher temperatures are used, typically 40-100°C, in order to complete the drying of solvents and accelerate the polymerization of paint, and therefore paint hardening. From the point of view of process time, drying is the longest step.
  • flashing off is performed with low air flows, so as not to disturb the distension of paint, both in supply and in exhaust of the total air flow.
  • airflows are important and typically are recirculated (70-80%), taking the rest percentage of air flow from the environment, heating the air for drying pieces before sending it on the pieces and exhausting a percentage of air coming from the oven that is analogous to the quantity withdrawn from the environment.
  • CN214440639U of Jiangsu Yutong Drying Equipment describes an oven for drying paint working in a closed circuit, without emitting heat outside, which can be recovered through a heat pump. Said oven can recover organic solvents and humidity evaporated from paint. Said oven comprises a heat pump that is used for energy saving but that does not recover energy from the air exhausted from the oven, as there is no air exhausted in the environment.
  • CN204902530U of Hefei Taoneng Environment Science & Technology describes a system for recovering energy from a drying environment comprising an air heater in the main channel. Downstream the heat pump there is a heat exchanger. The heat pump is used in order to preheat the air coming from the environment, but does not recover heat generated by the oven itself.
  • CN210725526U of Yancheng Tianyue Xiafeng Electronic Tech describes a system for drying circuit boards which does not take and does not exhaust air from/into the environment.
  • the closed system for recirculating air has the aim of condensing the substances evaporated during the baking of circuit boards and of heating the recirculated air again.
  • EP3430337A1 of the same applicant describes the functioning of vertical multilevel ovens, which typically comprise a plurality of trays superimposed in a plurality of adjacent vertical stacks contained inside transit vertical chambers, along which said trays are translated through lifting chain provided so that said trays follow a closed meandering path.
  • CN109682206A of Fujian Ronghua Science and Tech CO LTD describes a furnace body for polymerizing lithium iron phosphate in the field of battery production.
  • the heating and cooling system comprises an air heat pump.
  • the furnace environment is filled with an inert gas for a process with hot gas wherein there is not recirculation, but replacement of the oxygen in the drying chamber with pre-heated nitrogen through a heat pump, keeping the furnace closed at its ingress and egress. Once the furnace is opened, the gas must be replaced.
  • the furnace works in batch, not in a continuous way. There is no hint of the use of a heat pump also for the cooling, and the heat pump is simply used as a replacement for electric heaters.
  • the flashing off occurs in the lower portion of the first chamber, the drying in the higher portion of the first chamber and of the following chamber (second or third chamber if the central chamber is empty), and the cooling down in the lower portion of said chamber.
  • the present invention provides ovens wherein the energy used by the tunnel oven or vertical multilevel oven for flashing off and drying pieces (portion c) is the energy supplied to the compressor of the heat pump. Obviously supplying energy for the conveying of pieces (portion a) and the working of fans (portion b) remains necessary, but such energy is not different in the ovens according to the present invention in comparison with known art ovens.
  • the oven that is at temperature of the environment when switched on, is empty, i.e. does not contain painted pieces to be dried. Once the desired working temperature is reached thanks to the action of the compressor recovering thermal energy from the environment, the painted pieces are loaded into the oven and the paint covering them can start to be dried.
  • the oven is supplied with the pieces to be dried in a continuous way.
  • the heat transfer occurs between the condenser and the evaporator of the heat pump, respectively; the condenser directly heats the drying fluid of the oven and the evaporator recovers the heat at the exhaust through a water exchanger.
  • a fourth advantage is that, according to the known art, there must be provided a boiler for generating hot water, which water must be supplied to the points of use through circuits and pumps.
  • the plant can be markedly simplified, in that the heat pump can be installed directly on an oven or a group of adjacent ovens with a simplified dedicated plant, requiring only electrical supply.
  • Figure 1 First embodiment, tunnel oven according to the known art, lateral view
  • FIG. 4 First embodiment, tunnel oven according to the present invention, water/water embodiment, lateral view;
  • Figure 6 Second embodiment, known art vertical oven provided with four chambers and four stacks, axonometric view;
  • Figure 7 Second embodiment, known art vertical oven provided with four chambers and four stacks, axonometric view;
  • Figure 8 Second embodiment vertical oven drying chamber according to known art, longitudinal section;
  • FIG. 9 Second embodiment, vertical oven drying chamber according to the present invention, longitudinal section, air/water embodiment;
  • FIG. 10 Second embodiment, vertical oven drying chamber according to the present invention, longitudinal section, air/air embodiment;
  • FIG. 11 Second embodiment, vertical oven drying chamber according to the present invention, longitudinal section, water/water embodiment;
  • Figures 1-5 show the first embodiment of the present invention, i.e. a tunnel oven
  • Figures 6-12 show the second embodiment, i.e. a vertical multilevel oven.
  • the drying chamber 6 takes the shape of a tunnel
  • the drying chamber 6 takes the shape of a vertical chamber containing a stack of trays and adjacent to at least another vertical chamber. From the point of view of the drying process, the aim of the tunnel or of the vertical chamber is the same: maintaining pieces to be dried at the desired temperature for a pre-defined time.
  • a fan 4 placed at the egress of the pieces of the drying chamber 6 blows a drying fluid, e.g. hot air, through a diffuser 5 inside said tunnel 6.
  • a drying fluid e.g. hot air
  • Said drying fluid, that released its heat to the drying pieces 2 is suctioned by an inlet 7 placed at the piece’s ingress of the drying chamber 6: a first portion 9 (20-30%) of said drying fluid is suctioned by an exhaust flow- adjustable fan 8 and is discharged outside, in order to remove at least a portion of the solvents of the paint.
  • Said drying fluid is typically discharged outside the oven, and therefore its heat is dispersed in the environment.
  • a second portion 12 of the drying fluid (80-70%) is recirculated through a recirculating channel 10 inside an air treatment group 30 providing recirculation, comprising an inlet for recirculating air 12 and an inlet for air 11 coming from the environment; both are typically provided with an adjustable shutter.
  • the sum of the outside air flow 11 and recirculated air 12 is filtered through a filter 13 and heated through a heat exchanger 14 before reinserting it in the oven through said fan 4.
  • said heat exchanger 14 is an exchanger using water as working intermediate fluid.
  • Figure 2 shows an oven 100 provided with a heat pump 15 according to the present invention; this preferred embodiment realizes an air/water exchange.
  • Said heat pump comprises in a known way an evaporator 16, a condenser 18, a compressor 17, an expansion valve 19.
  • the drying fluid flow 9 e.g. air, exhausted from the exhaust fan 8, typically 20-30% of the drying fluid circulating in the oven 100, is conveyed through a closed circuit to the heat pump 15, in particular to the evaporator 16, that is configured as a heat exchanger between said drying fluid and the refrigerant gas of the heat pump.
  • the exhaust air flow 9 releases heat to the refrigerant fluid of the heat pump, being exhausted outside the plant as air flow 23, having a lower temperature than the temperature of the exhaust air flow 9 at its arrival in the exhaust.
  • the refrigerant fluid that is the working fluid inside the circuit of the heat pump 15, according to its normal cycle, is brought to a higher pressure by the compressor 17, so increasing its temperature.
  • This heat is released from the condenser 18 of the heat pump configured as heat exchanger to an intermediate fluid, preferably hot water, circulating in a circuit 20 by means of a pump 21.
  • Said hot water supplies the heat exchanger 14 of the oven 100, while the refrigerant fluid outputting from the condenser of the heat pump through the expansion valve 19 is brought to the evaporator 16 again, at a lower pressure and temperature.
  • the above-described air-water thermal exchange is the preferred embodiment, but different thermal exchanges can be realized in alternative embodiments.
  • Figure 3 shows an alternative embodiment of an air/air oven 101, wherein the exhaust drying fluid flow 9, preferably air, releases its heat directly to the evaporator 16, while an air flow 24 (corresponding to the air flow 11 of Figures 1 and 2) coming from the environment is heated passing through the condenser 18 configured as a heat exchanger, before entering into the air treatment group 30 through an air duct 25 and mixed with a recirculated air flow 12, so dispensing with the hot water circuit 20, the heat exchanger 14 and the recirculating pump 21 according to the embodiments shown in Figures 1 and 2.
  • This embodiment has the least requirements from the plant point of view.
  • FIG 4 shows an alternative embodiment of a water/water oven 102, wherein there is provided an exchange intermediate fluid, e.g. water, that is circulated in heat exchangers 14 and 27 through pumps 21 and 26, wherein the drying fluid flow 9 exhausted from the oven releases its heat to the intermediate fluid, i.e. water, in the heat exchanger 27.
  • Said intermediate fluid releases the heat to the evaporator 16 configured as a heat exchanger and connected through a closed circuit with a recirculation pump 26 to the heat exchanger 27, while the condenser 18 is the heat exchanger with an intermediate fluid, e.g. water, to which releases the heat of the refrigerant fluid of the heat pump 15, heat that is transferred to the heat exchanger 14.
  • the heat exchanger 14 transfers heat to the mix of air 11 taken from the environment and to the portion 12 of drying fluid intended to be re-inserted in the oven through the air treatment group 30 in the heat exchanger of said treatment group 30.
  • the evaporator 16 recovers heat from said portion of drying fluid; this occurs in an indirect way, as the heat of the portion of drying fluid 9 exhausted from the oven used in order to heat said intermediate fluid, e.g. water, through a heat exchanger 27, while said heated water coming out from the heat exchanger 27 is used as intermediate fluid to transfer heat to the refrigerant fluid of the heat pump through the evaporator 16 configured as heat exchanger. Said air is heated through a thermal exchange with the refrigerant fluid of the heat pump in the condenser 18, configured as heat exchanger.
  • said intermediate fluid e.g. water
  • Figures 6-12 and the Description hereunder refer to the second embodiment of the present invention, i.e. vertical multilevel ovens.
  • FIG. 6 shows a typical oven 61 having four chambers 71, 72, 73, 74 and four stacks 81, 82, 83, 84 according to the known art.
  • the flashing off of (not shown) pieces, supported by trays 3 occurs; in the two central chambers 72 and 73 the drying of pieces occurs; while in the last chamber 74 the cooling off of the pieces occurs, before their egress from the oven.
  • a filter 13 for filtering the flow of air 11 and /or 12;
  • a fan 4 supplying said air flows 11 and/or 12 or their mix into the drying chamber 6.
  • At least a heat pump 15 is added, so as to recover the heat otherwise dispersed in the environment by the exhaust airflow 9.
  • the evaporator 16 recovers heat from the exhausted portion 9 of the drying fluid, and this occurs indirectly, as the heat of the portion of drying fluid exhausted from the oven is used to heat said intermediate fluid, e.g. water, through a water heat exchanger 27. Said heated water outcoming from the heat exchanger 27 is used as intermediate fluid to transfer heat to the refrigerant fluid of the heat pump thanks to the evaporator 16 configured as a heat exchanger.
  • said intermediate fluid e.g. water
  • the temperature of the air used for drying pieces 2 is about 60-70°C; the temperature of exhaust air 9 coming from the fan 8 is about 10°C lower.
  • the temperature of the mix of the air 22 coming from environment and of the exhaust air 9 of the oven must be higher than the temperature of the fluid circulating in the evaporator 16, in order to obtain an efficient heat exchange.
  • the air treatment group 30 brings back air to the process temperature, i.e. 60-70°C.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

Four tunnel à un ou plusieurs niveaux (100, 101, 102, 103) de séchage/vaporisation à travers un traitement superficiel de fluide de séchage tel que des peintures ou des colles appliquées sur des pièces (2) transitant par une chambre de séchage (6) possédant la forme d'un tunnel, ledit four comprenant : a. un système de transport (3) desdites pièces (2) : b. un groupe de traitement de l'air (30), comprenant à son tour : - une entrée d'air recyclé (12) ; -une entrée d'air (11) provenant de l'environnement ; - éventuellement un filtre (13) pour filtrer lesdits flux d'air (11 et/ou 12) ou leur mélange (11 et 12) ; - éventuellement un échangeur de chaleur (14) qui peut utiliser ou non un fluide intermédiaire ; un ventilateur (4) fournissant lesdits flux d'air (11 et/ou 12) ou leur mélange dans la chambre de séchage (6) ; c. éventuellement un ventilateur d'échappement (8) ; d. au moins une pompe à chaleur (15) comprenant : un évaporateur (16), un compresseur (17), un condenseur (18), un détendeur (19) et un fluide frigorigène, ledit évaporateur (16) et ledit condenseur (18) étant configurés pour transférer de l'énergie thermique entre le fluide frigorigène de ladite pompe à chaleur et un autre gaz ou fluide liquide, ladite chambre de séchage (6) étant fonctionnellement reliée à ladite au moins une pompe à chaleur (15), le fluide de séchage comprenant : une première partie de fluide de séchage d'échappement (9) qui est évacuée dans l'environnement ; éventuellement une seconde partie de fluide de séchage (12) qui est remise en circulation à l'intérieur dudit four (100, 101, 102, 103) ; éventuellement ledit fluide de séchage étant chauffé à travers le contact avec un fluide intermédiaire, caractérisé en ce que ladite première partie (9) de fluide de séchage est placée dans un état de transfert de chaleur thermique direct, ou de transfert de chaleur thermique indirect à travers un fluide intermédiaire pour transfert thermique, avec le fluide frigorigène de ladite pompe à chaleur (15) afin de récupérer son énergie thermique avant de disperser ladite première partie de fluide de séchage dans l'environnement ; et en ce que l'énergie utilisée pour le processus de séchage/vaporisation de peinture est l'énergie nécessaire pour alimenter le compresseur (17) de la pompe à chaleur (15).
PCT/EP2023/087727 2022-12-29 2023-12-22 Four de séchage à l'air avec économie d'énergie WO2024141504A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
IT202200027132 2022-12-29
IT202200027129 2022-12-29
IT102022000027129 2022-12-29
IT102022000027132 2022-12-29

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WO2024141504A3 WO2024141504A3 (fr) 2024-08-22

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Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4173924A (en) 1978-03-01 1979-11-13 Schweitzer Industrial Corporation Paint spray booth with air supply system
GB2078651A (en) 1980-06-24 1982-01-13 Lienhard Ag Cabinet with two stacks formed of container units
IT221807Z2 (it) 1991-04-10 1994-10-20 Cefla Coop Forno verticale a vassoi con tempo di permanenza regolabile dei pezzi in trattamento
IT1309018B1 (it) 1999-03-02 2002-01-15 Cefla Coop Forno verticale con possibilita' di funzionamento a ciclo breve.
EP2609021B1 (fr) 2010-08-24 2014-10-29 Hänel & CO. Système de rayonnage pour le stockage de produits à stocker
CN204902530U (zh) 2015-07-22 2015-12-23 合肥淘能环境科技有限公司 一种烘房热回收热泵装置
EP3430337A1 (fr) 2016-03-18 2019-01-23 CEFLA Società Cooperativa Four vertical pour des pièces principalement plates
CN109569989A (zh) 2018-11-09 2019-04-05 同济大学 使用热泵热回收和桶泵循环的锂电池极片涂布机烘干系统
CN109682206A (zh) 2018-12-13 2019-04-26 福建荣华科技有限公司 高效烧结炉以及磷酸铁锂生产装置
CN210725526U (zh) 2019-11-15 2020-06-09 盐城天锐先锋电子科技有限公司 一种电路板烘烤箱
CN214440639U (zh) 2021-02-22 2021-10-22 江苏宇通干燥工程有限公司 一种烘干油漆用烘箱
EP3767215B1 (fr) 2019-07-19 2022-03-02 Wienerberger AG Installation de cuisson des ébauches d'ouvrages céramiques

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4173924A (en) 1978-03-01 1979-11-13 Schweitzer Industrial Corporation Paint spray booth with air supply system
GB2078651A (en) 1980-06-24 1982-01-13 Lienhard Ag Cabinet with two stacks formed of container units
IT221807Z2 (it) 1991-04-10 1994-10-20 Cefla Coop Forno verticale a vassoi con tempo di permanenza regolabile dei pezzi in trattamento
IT1309018B1 (it) 1999-03-02 2002-01-15 Cefla Coop Forno verticale con possibilita' di funzionamento a ciclo breve.
EP2609021B1 (fr) 2010-08-24 2014-10-29 Hänel & CO. Système de rayonnage pour le stockage de produits à stocker
CN204902530U (zh) 2015-07-22 2015-12-23 合肥淘能环境科技有限公司 一种烘房热回收热泵装置
EP3430337A1 (fr) 2016-03-18 2019-01-23 CEFLA Società Cooperativa Four vertical pour des pièces principalement plates
CN109569989A (zh) 2018-11-09 2019-04-05 同济大学 使用热泵热回收和桶泵循环的锂电池极片涂布机烘干系统
CN109682206A (zh) 2018-12-13 2019-04-26 福建荣华科技有限公司 高效烧结炉以及磷酸铁锂生产装置
EP3767215B1 (fr) 2019-07-19 2022-03-02 Wienerberger AG Installation de cuisson des ébauches d'ouvrages céramiques
CN210725526U (zh) 2019-11-15 2020-06-09 盐城天锐先锋电子科技有限公司 一种电路板烘烤箱
CN214440639U (zh) 2021-02-22 2021-10-22 江苏宇通干燥工程有限公司 一种烘干油漆用烘箱

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