+

WO2018033665A1 - Procédé et agencement pour la recirculation d'air dans un processus de séchage - Google Patents

Procédé et agencement pour la recirculation d'air dans un processus de séchage Download PDF

Info

Publication number
WO2018033665A1
WO2018033665A1 PCT/FI2017/050580 FI2017050580W WO2018033665A1 WO 2018033665 A1 WO2018033665 A1 WO 2018033665A1 FI 2017050580 W FI2017050580 W FI 2017050580W WO 2018033665 A1 WO2018033665 A1 WO 2018033665A1
Authority
WO
WIPO (PCT)
Prior art keywords
air flow
exhaust air
drying process
arrangement
scrubber
Prior art date
Application number
PCT/FI2017/050580
Other languages
English (en)
Inventor
Markus Hallapuro
Original Assignee
Tm System Finland Oy
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 Tm System Finland Oy filed Critical Tm System Finland Oy
Priority to DE112017004101.5T priority Critical patent/DE112017004101B4/de
Publication of WO2018033665A1 publication Critical patent/WO2018033665A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/003—Supply-air or gas filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
    • F26B25/005—Treatment of dryer exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/02—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure
    • F26B21/04—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure partly outside the drying enclosure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F26B21/08—Humidity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F26B21/08—Humidity
    • F26B21/083—Humidity by using sorbent or hygroscopic materials, e.g. chemical substances, molecular sieves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F26B21/08—Humidity
    • F26B21/086—Humidity by condensing the moisture in the drying medium, which may be recycled, e.g. using a heat pump cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B23/00—Heating arrangements
    • F26B23/001—Heating arrangements using waste heat
    • F26B23/002—Heating arrangements using waste heat recovered from dryer exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Definitions

  • the invention relates to a method and an arrangement for recirculating air in a drying process.
  • Drying is an energy intensive operation due to the high latent heat of vaporization and the inefficiency of using hot air as the drying medium.
  • moisture is removed from a product into an air flow creating a moisture laden exhaust air flow.
  • An object of the present invention is to solve the above mentioned drawbacks and to provide an efficient and cost effective method and an arrangement for implementing the method for recirculating air in a drying process.
  • An arrangement for recirculating air in a drying process within a plant comprises an exhaust air flow from a drying process.
  • the arrangement comprises a device for reducing the moisture content of the exhaust air flow.
  • the arrangement comprises means for dividing the exhaust air flow exiting the device at least into an air flow recirculated to the drying process and into an air flow to at least one room related to the drying process.
  • An advantage of the method and arrangement of the invention is that the amount of the exhaust air flow exhausted to the atmosphere and the formation of visible water vapour plumes can be reduced to minimum.
  • Figure 1 shows an arrangement for recirculating air in a drying pro- cess
  • Figure 2 shows an arrangement for recirculating air in a drying process with heat recovery exchangers
  • Figure 3 shows an arrangement for recirculating air in a drying process comprising a cleaning unit
  • Figure 4 shows an arrangement for recirculating air in a drying process comprising a cleaning unit
  • Figure 5 shows an arrangement for recirculating air in a drying process comprising a cleaning unit, a supplementary air flow and a venturi scrubber.
  • Figure 1 shows an arrangement for recirculating air in a drying process.
  • moisture is removed from a product into a hot air flow creating a moisture laden exhaust air flow 2a.
  • the drying process 1 is preferably continuous energy intensive drying process where the moisture laden exhaust air flow 2a may comprise 130-160 grams of water vapour per kg of air, for instance. Examples of continuous energy intensive drying processes are drying of paper, pulp, wood, lumber or waste sludge.
  • a device 3 reduces the moisture content of the exhaust air flow 2a.
  • the device 3 cools the exhaust air flow 2a to remove moisture, or absorbs moisture from the exhaust air flow 2a, or adsorbs moisture from the exhaust air flow 2a, or performs any combination of these three, for instance.
  • the reduction of moisture content of the exhaust air 2a reduces the visible water vapour in the exhaust air flow 2a when it is exhausted from the device 3.
  • the water vapour becomes visible as a result of water vapour condensing and forming water droplets. Clouds or fog are visible forms of atmospheric water vapour.
  • At least part of the exhaust air flow 2b-c exiting the device 3 is recirculated to the drying process 1.
  • the reduction of the water vapour in the exhaust air flow 2b-c and the recirculation of the exhaust air 2b-c reduces the amount of the exhaust air flow exhausted to the atmosphere and the formation of visible water vapour plumes.
  • Plumes of the moisture-laden exhaust air 2a have high moisture content, and exhausting them to atmosphere under certain meteorological conditions without adequate moisture removal would result in visible plume formation.
  • the visible water vapour plume formation depends on meteorological conditions such as wind speed, wind direction, atmospheric stability class, ambi- ent temperature, mixing heights, and relative humidity of the ambient air.
  • the exhaust air flow 2b-c exiting the device 3 is divided at least into a recirculated air flow to the drying process 2b and into an air flow to at least one room related to the drying process 2c.
  • the air flow divided to the drying process 2b comprises 65-85% and the air flow divided to at least one room related to the drying process 2c comprises 35-15% of the exiting exhaust air flow 2b-c, for instance.
  • the space surrounding the drying process 1 is not leak-proof and typi- cally the amount of recirculated dry air 2b brought to the space is less than the amount of moisture laden exhaust air 2a drawn from the space.
  • Typical examples of rooms related to the drying process 1 are finishing treatment rooms, service spaces, control and electrical rooms, machine room, finishing area, special rooms such as motor control center and rack rooms.
  • the at least one room related to the drying process may comprise a production area of a plant where the drying process is part of the production process.
  • the air flow 2c divided from the dried and cooled exhaust air flow 2b-c exiting the device 3 may be used for heating, cooling or ventilating the room or rooms related to the drying process 1.
  • the inlet air to the rooms related to the drying process 1 taken from outdoor needs to be heated and preferably humidified for maintaining ideal working conditions for the personnel and plant machinery.
  • the recircula- tion of the exhaust air 2b also to the rooms related to the drying process 1 is advantageous as it improves their inlet air quality and at the same time reduces the amount of the exhaust air flow exhausted to the atmosphere and the formation of visible water vapour plumes.
  • the method and the arrangement for recirculating air in a drying process allows a full recirculation of exhaust air on a stable produc- tion flow of the plant particularly during a cold and dry season of the year.
  • a wet scrubber 28 is utilized for reducing the temperature and the moisture content of a moisture laden exhaust air 2a from a drying process 1, i.e. the moisture laden exhaust air 2a is dried in a wet scrubber 28.
  • the scrubber 28 is advantageous in drying the moisture laden exhaust air as it offers large volume for the heat and mass transfer.
  • the wet scrubber 28 is cost effective as the required heat and mass transfer surface is considerably lower compared to conventional plate heat exchanger systems or a tube-in-a-shell heat exchanger systems. Further, the scrubber 28 also removes unwanted substances from the moisture laden exhaust air 2a. Examples of removable substances are dust, dirt, odorous vapours and water soluble chemicals.
  • the moisture laden exhaust air flow 2a from a drying process 1 is guided to a wet scrubber 28 for reducing the moisture content and the temperature of the exhaust air flow 2a.
  • Part of the exhaust air 2b is recir- culated to the drying process 1 and part of the exhaust air 2c is led to at least one room related to the drying process 1.
  • the scrubber 28 comprises a scrubber tower which has a circular base surface 4 and a cylindrical shell 5. Another base shape may be rectangular, for instance.
  • the moisture laden exhaust air flow 2a is guided horizontally to the bottom part 6 of the wet scrubber tower through an inlet opening 7.
  • the flow guiding may comprise pressurizing the moisture laden exhaust air flow with one or more fans 8.
  • the exhaust air flow 2a flows upwards and droplets 9 of a cooling water 10 are injected into the exhaust air flow from a plurality of nozzles 11.
  • the cooling water droplets 9 are flowing down-wards in counterflow to the exhaust air flow 2a.
  • the moisture laden exhaust air 2a collides with the cooling water 10 creating a turbulent zone where the air/water interface is continuously and rapidly renewed. Scrubbing is effectively accomplished by the thorough mixing of the exhaust air 2a and scrubbing cooling water 10 in the scrubber 28.
  • Air is saturated when it has reached its water vapour capacity and contains all the water vapour that it can hold at a particular temperature. In saturated air, the water vapour content equals its capacity. At the dew point temperature the air is saturated, and the dew point is the temperature at which the relative humidity of the air is 100%. In the scrubber 28 the dew temperature of the cooling water 10 is lower than the dew temperature of the exhaust air flow 2a.
  • the dried and cooled exhaust air 2b-c is discharged from the scrubber 28 through one or more exhaust air outlets 12 at the top part 13 of the scrubber shell 5.
  • the scrubber 28 may comprise an outlet 12 to atmosphere as shown in Figure 4 which is used during the start-up or halting of the scrubber 28, for instance.
  • the state of exiting exhaust air 2b-c may be controlled.
  • the arrangement comprises means for measuring the temperature and the moisture content of the exhaust air flow 2b-c exiting the scrubber 28.
  • the temperature and moisture content of the exhaust air 2b-c exiting from the scrubber 28 may be measured by a wet and dry bulb thermometers, for instance, or other online humidity measuring devices may be used.
  • the arrangement comprises means for comparing 15 the measured temperature and the moisture content values to set values for the exit- ing exhaust air flow 2b-c.
  • the comparison may be made with a control algorithm provided in a control device or a computer, for instance.
  • the temperature and moisture content of the exhaust air flow lb-c exiting the scrubber 28 are measured, the measured temperature and the moisture content values are compared to set values for the exit- ing exhaust air flow 2b-c and based on the comparison result the cooling water 10 flow to the plurality of nozzles 11 and the pressure at the plurality nozzles 11 is controlled.
  • the set values for the exiting exhaust air 2b-c from the scrubber 28 depend on the drying process 1 into which the exiting exhaust air 2b-c is recirculated. However, the moisture content of the exiting exhaust air 2b-c has to be low enough to have free water vapour capacity.
  • the set value range maximum for from the scrubber 28 exiting exhaust air 2b-c temperature preferably comprises 35°C, and the set value range maximum for the moisture content of from the scrubber 28 the exiting exhaust air 2b-c preferably comprises 35 grams of water vapour per kg of air.
  • a suitable set value range for the from the scrubber 28 exiting exhaust air 2b-c temperature could comprise 25-35°C
  • the set value range for the moisture content of from the scrubber 28 exiting exhaust air 2b-c could comprise 20-35 grams of water vapour per kg of air, preferably 25-30 grams of water vapour per kg of air.
  • the arrangement further comprises means for controlling 16 the cooling water 10 flow to the plurality of nozzles 11 and the pressure at the plurality of nozzles 11 based on the comparison result.
  • the controlling means 16 is able to reduce or increase the cooling water 10 flow to the plurality of nozzles 11 and to reduce or increase the pressure at the plurality of nozzles 11.
  • the controlling of the cooling water 10 flow to the plurality of nozzles 11 and the pressure at the plurality of nozzles 11 may be performed with pumps
  • valves or with adjustable nozzles, for instance.
  • the scrubber 28 comprises three successive modules 18a-c arranged on top of each other in the vertical direction y.
  • a module 18a-c arranged on top of each other in the vertical direction y.
  • the 18 comprises a row of a plurality of spraying nozzles 11 for injecting droplets 9 of a cooling water 10, a mass transfer area 19a-c where the exhaust air 2a collides with droplets 9 of the cooling water 10, a droplet separator 20a-c for separating droplets from the exhaust air 2 and a water collecting tray 21a-c for collecting the separated droplets from the droplet separator 20a-c.
  • the mass transfer area 19a- c is created below each row of a plurality of nozzles 11.
  • the droplet separator 20a-c and a water collecting tray 21a-c are arranged above the plurality of nozzles 11 as the exhaust air flow 2a moves upwards in vertical direction y.
  • the number of the modules is preferably from 2 to 5 in one scrubber. In some cases it is possible to use only one module 18a-c if the required reduction in the moisture content and the temperature of the moisture laden exhaust air 2a is small.
  • the droplets 9 of the cooling water 10 are injected to the mass transfer area 19a-c created below the row of a plurality of nozzles 11, and the droplets moving upwards with the exhaust air flow 2a are separated in the droplet separator 20a-c and the droplet separator 20a-c is drained to the water collecting tray 21a-c.
  • the droplet separator 20a-c is arranged above the water collecting tray 21a-c and may further comprise a shape for creating a falling film from the separated droplets.
  • the arrangement may further comprise means for controlling the size of the droplets 22 of the cooling water 10 in each module 18a-c.
  • Droplets 9 are usually described by their perceived size, i.e., diameter.
  • the controlling of the size of the droplets may be performed with pumps 17 and tanks 27, or with adjustable nozzles, for instance.
  • the size of the droplets 9 of the cooling water 10 may be controlled.
  • the size of the droplets 9 of the cooling water 10 is be controlled by controlling the pressure at the row of the plurality of nozzles 11, and the controlling of the size of the droplets 9 is performed separately for each mod- ule 18a-c.
  • the size of the droplets 9 is the smallest at the plurality of nozzles 11 located in the bottom part 6 of the shell 5 and increases towards the vertically y higher located nozzles being the greatest at the plurality of nozzles 11 in the top part 13 of the shell 5.
  • the cooling water 10 is first fed to the plurality of nozzles 11 in the top part 13 of the shell 5, i.e. to the vertically highest located module 18c. Then the subsequent modules 18a-b in a vertically descending order use the cooling water 10 collected from the previous modules 18c.
  • This kind of layout minimizes the use of cooling water 10 in the scrubber 28.
  • other layouts are also applicable. For instance, if the cooling water 10 temperature is high compared to the required moisture content and temperature values for the exhaust air flow 2b-c exiting the scrubber 28 then it may be necessary to provide the first two highest located modules 18b-c with the cooling water 10 at its original temperature.
  • the scrubber 28 may comprise at least two droplet separators 20a-c and the vertically y upper mounted droplet separator 20c is connected to a flowing cooling media for providing a cooled separator surface.
  • the method may then comprise the step of cooling the vertically upper droplet separator 20c with a flowing cooling media for providing a cooled separator surface.
  • the arrangement comprises means for recirculating 29 at least part of the dried and cooled exhaust air flow 2b-c exiting the scrubber 28 to the drying process 1 where in the drying process 1 moisture is removed from the product into the dried and cooled exhaust air flow 2b creating a moisture laden exhaust air flow 2a which is guided to the scrubber 28.
  • the means for recirculating 29 may comprise a piping and a fan, for instance.
  • the cooling water 10 can comprise raw water.
  • the scrubber In the scrubber
  • 28 used cooling water may then be utilized in a production process of the product which is dried in the drying process 1. This arrangement reduces the energy consumption of the plant comprising the drying process as from the reduction of the water vapour from the exhaust air flow obtained heat is transferred to the cooling water 10.
  • the temperature of raw water is low during the winter time at many geographic locations.
  • Low cooling water 10 temperature intensifies the moisture removal of the exhaust air 2a in the scrubber 28. This is advantageous as at the same time the occurrence of the visible water vapour plumes becomes high if the exhaust air 2a is exhausted to the atmosphere.
  • the cooling water 10 is preferably filtered to reduce the amount of possible solid particles in it for avoiding choking of the plurality of nozzles 11.
  • the cooling water 10 in the scrubber 28 can comprise water soluble substance and water solution, e.g. liquid caustic soda. Further, it may comprise chemicals for reducing the surface tension of the water.
  • the method for recirculating air may comprise the steps of filtering the cooling water 10 and adding chemicals to the cooling water 10 for reducing the surface tension of the cooling water 10.
  • the temperature of the cooling water 10 rises as the cooling water 10 flows downwards in the scrubber 28.
  • the temperature of the cooling water 10 exiting from the scrubber bottom 6 is preferably 2-3°C lower than the temperature of the moisture laden exhaust air flow 2a at the inlet 7 on the bottom 6 of the scrubber 28.
  • the bottom 6 of the scrubber 28 comprises an outlet 23 for discharging the cooling water 10 from the scrubber 28.
  • Figure 2 shows an arrangement for recirculating air in a drying process 1 with a multi-stage heat recovery system 24.
  • the arrangement of Figure 1 is connected to a three stage heat recovery system 24 comprising three heat recovery heat exchangers 25a-c arranged in series.
  • the heat recovery heat exchangers 25a-c are equipped with washers 26a-c for batch washing.
  • the moisture laden exhaust air 2a transfers heat to inlet air of the drying process, i.e. to the dried and cooled exhaust air 2b flowing from the device 3.
  • the device 3 comprises a scrubber 28.
  • the moisture laden exhaust air 2a transfers heat to other flowing media. From the multi-stage heat recovery system 24 the moisture laden exhaust air 2a is guided to the device 3, e.g. the scrubber 28.
  • the arrangement may comprise two or more devices 3 ar- ranged in parallel for increasing air recirculating capacity for the drying process 1.
  • the set values for the exiting exhaust air 2b-c from each device 3 are preferably substantially the same.
  • the moisture laden exhaust air flow 2a from the drying process 1 is then guided to two or more devices 3 arranged in parallel.
  • the scrubber 28 dimensions depend on the drying process 1 from and into which the exiting exhaust air 2a-c is recirculated and on the available cooling water temperature 10 for the drying and cooling of the moisture laden exhaust air 2a.
  • the dimensioning method comprises the steps of: determination of the scrubber tower diameter based on the volumetric flow rate of the moisture laden exhaust air 2a and the moisture laden exhaust air 2a velocity through the scrubber 28; determination of the number and the height of modules 18a-c required for dehumidification and cooling based on mole fractions in the exhaust air 2a at the inlet and outlet and on the required exhaust air 2a residence time in the droplet 9 flow; calculating a total volume of spray section based on the number of modules 18a-c, the overall volumetric gas phase mass transfer coefficient and the flow rate of the gas phase.
  • Figure 3 shows an embodiment of an arrangement for recirculating air in a drying process where the arrangement comprises a cleaning unit 30.
  • the moisture laden exhaust air flow 2a from a drying process 1 is guided to a cleaning unit 30 for cleaning the exhaust air 2a before it enters to the device 3 which device 3 reduces the moisture content of the exhaust air flow 2a.
  • the cleaning unit 30 is arranged in front of the device 3 in the flow direction of the exhaust air flow 2a.
  • the cleaning unit 30 cleans the exhaust air flow 2a by reducing the contaminant content of the exhaust air flow 2a.
  • the cleaning unit 30 cleans the exhaust air flow 2a by removing at least part of the unwanted substances from the moisture laden exhaust air 2a. Examples of removable substanc- es are dust, dirt, odorous vapours and water soluble chemicals.
  • the cleaning unit 30 comprises a scrubber.
  • the exhaust air flow 2a flows upwards and droplets of a washing water 31a are injected into the exhaust air flow from a plurality of nozzles 11.
  • the exhaust air 2a is scrubbed with the washing water 31a.
  • the washing water 31a is recirculated with preferably adding some fresh water 31b.
  • Cleaning chemicals 32 e.g. NaOH, may also be added.
  • Water overflow 31c the excess amount of water overflows to water treatment.
  • the washing water 31a circulation is relatively closed where the amount of added fresh water 31b comprises 18-25% of the circulated washing water 31a.
  • the cleaned exhaust air flow 2a is guided into the bottom part 6 of the device 3 through an inlet opening 7.
  • the cleaning unit 30 and the device 3 are two separate equipment connected with a flow channel 33.
  • the cleaning unit 30 is not contained in the shell 5 of the device 3.
  • the cleaning unit 30 reduces the contaminant content of the exhaust air flow 2a entering the device 3. Therefore the contaminant content of the cooling water 10 used in the device 3, e.g. in the scrubber 28, remains on a lower level. Thus the cooling water 10 having a low contaminant level may then be reused more efficiently in the device 3 requiring less fresh water.
  • the washing water 31a consumption in the cleaning unit 30 comprises 15-25% of the cooling water 10 consumption of the device 3.
  • Figure 4 shows an embodiment of an arrangement for recircu- lating air in a drying process where the arrangement comprises a cleaning unit 30.
  • the moisture laden exhaust air flow 2a from a drying process 1 is guided to a cleaning unit 30 for cleaning the exhaust air 2a before it enters to the device 3 which device 3 reduces the moisture content of the exhaust air flow 2a.
  • the cleaning unit 30 is arranged inside the shell 5 of the device 3.
  • the clean- ing unit 30 is arranged to the bottom part 6 of the shell 5 surrounding the device 3.
  • the cleaning unit 30 is in front of the device 3 wherein the moisture content of the exhaust air flow 2a is reduced in the flow direction of the exhaust air flow 2a.
  • the cleaning unit 30 cleans the exhaust air flow 2a by reducing the contaminant content of the exhaust air flow 2a.
  • the cleaning unit 30 cleans the exhaust air flow 2a by removing at least part of the unwanted substances from the moisture laden exhaust air 2a. Examples of removable substances are dust, dirt, odorous vapours and water soluble chemicals.
  • the cleaning unit 30 comprises a scrubber.
  • the exhaust air flow 2a flows upwards and droplets of a washing water 31a are injected into the exhaust air flow from a plurality of nozzles 11.
  • the exhaust air 2a is scrubbed with the washing water 31a.
  • the washing water 31a is recirculated with preferably adding some fresh water 31b.
  • Cleaning chemicals 32 e.g. NaOH, may also be added.
  • Water overflow 31c the excess amount of water overflows to water treatment.
  • the cleaned exhaust air flow 2a flows upwards.
  • the device 3 comprises a scrubber 28 comprising two successive modules 18d-e arranged on top of each other in the vertical direction y.
  • the cleaned exhaust air flow 2a flows upwards from the cleaning unit 30, i.e. from the scrubber comprising washing water 31, to a vertically lowest module 18c of the scrubber 28.
  • the vertically lowest module 18c of the scrubber 28 comprises an outlet 23 for discharging the cooling water 10 from the scrubber 28.
  • the cleaning unit 30 and the device 3 are two separate equipment contained in the same housing, in the shell 5 of the device 3.
  • the scrubber comprising washing water 31 cleaning the exhaust air 2a and the scrubber 28 reducing the moisture content of the exhaust air flow 2a have separate scrubbing water circulations, i.e. the washing water 31a circulation is separate from the cooling water 10 circulation.
  • the cleaning unit 30 reduces the contaminant content of the exhaust air flow 2a entering the device 3. Therefore the contaminant content of the cooling water 10 used in the device 3, e.g. in the scrubber 28, remains on a lower level. Thus the cooling water 10 having a low contaminant level may then be reused more efficiently in the device 3 requiring less fresh water.
  • the washing water 31a consumption in the cleaning unit 30 comprises 15-25% of the cooling water 10 consumption of the device 3.
  • Figure 5 shows an embodiment of an arrangement for recircu- lating air in a drying process comprising a cleaning unit, a supplementary air flow and a venturi scrubber.
  • Figure 5 shows the arrangement of Figure 3 provided with a supplementary air flow and a venturi scrubber between the cleaning unit 30 and the device 3.
  • cleaning unit 30 for cleaning the exhaust air 2a is similar to the cleaning unit 30 shown in Figure 3 and its operation is explained in the description of Figure 3.
  • the exhaust air 2a is cleaned in the cleaning unit 30 and the cleaned exhaust air 2a is led to one or more heat exchangers 34.
  • the exhaust air flow 2a is cooled with a supplementary air flow 35 in one or more heat exchangers 34.
  • the heat exchanger 34 is an air-to-air heat exchanger.
  • the type is a cross flow heat exchanger, for instance.
  • the supplementary air flow 35 comprises pref- erably outside air.
  • cooled exhaust air flow 2a is mixed with supplementary air flow 35 in a mixing chamber 36.
  • the mixture comprises 30-60% of exhaust air flow 2a, preferably 45-55%.
  • the relative humidity of the air flow comprising the cooled exhaust air flow 2a mixed with the supplementary air flow 35 is significantly less than 100%.
  • the aim of the mixing is to reduce the relative humidity of the air flow comprising the exhaust air flow 2a to allow a phase change in the venturi scrubber 37.
  • Additional fans 8 can be used to balance the exhaust air flow 2a and the supplementary air flow 35.
  • the exhaust air flow 2a mixed with supplementary air flow 35 is guided to a venturi scrubber 37.
  • the exhaust air flow 2a mixed with supplementary air flow 35 is cooled in a venturi scrubber 37.
  • the venturi scrubber 37 comprises a quench section providing evaporative cooling.
  • the venturi scrubber 37 comprises also a high pressure pump 38 to produce small droplets, i.e. mist, with a high water pressure for the venturi scrubber 37.
  • the air flow comprising the exhaust air flow 2a mixed with supplementary air flow 35 flows downwards in vertical direction in the venturi scrubber 37.
  • the one or more heat exchangers 34, the mixing chamber 36 and the venturi scrubber 37 are installed between the clean- ing unit 30 and the device 3 in the direction of the exhaust air flow 2a.
  • the arrangement comprises the components as shown and described with Figure 5 except the heat exchangers 34 for cooling the exhaust air 2a with the supplementary air flow 35.
  • the exhaust air 2a is guided directly to the mixing chamber 36.
  • the supplementary air flow 35 is also guided to the mixing chamber 36 where the exhaust air flow 2a is mixed with supplementary air flow 35.
  • the use of the supplementary air flow 35 increases the air flow volume from the device 3. Then the air flow divided to the drying process 2b comprises 32-18% and the air flow divided to at least one room related to the drying process 2c comprises 68-82% of the exiting exhaust air flow 2b-c, for in- stance.
  • FIG. 3 The embodiments of an arrangement for recirculating air in a drying process shown in Figures 3, 4 and 5 may be applied also to the arrangement shown in Figure 2 comprising a multi-stage heat recovery system 24. From the multi-stage heat recovery system 24 of Figure 2 the moisture laden exhaust air 2a is guided to the cleaning unit 30. Further, in Figures 3, 4 and 5 shown exhaust air 2b which exits device 3 flows then into a heat recovery exchanger 25a as shown in Figure 2 for being heated before it is recirculated to the drying process 1.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Drying Of Solid Materials (AREA)
  • Treating Waste Gases (AREA)
  • Separation Of Particles Using Liquids (AREA)

Abstract

L'invention concerne un procédé de recirculation d'air dans un processus de séchage (1), dans lequel, dans le processus de séchage (1), de l'humidité est éliminée d'un produit en un flux d'air créant un flux d'air d'échappement (2a). Le flux d'air d'échappement (2a) est guidé vers un dispositif (3) dans lequel la teneur en humidité du flux d'air d'échappement (2a) est réduite. Le flux d'air d'échappement (2b-c) sortant du dispositif (3) est divisé au moins en un flux d'air (2b) recirculé vers le processus de séchage (1) et en un flux d'air (2c) vers au moins une pièce associée au processus de séchage (1). L'invention concerne également un agencement de recirculation d'air dans un processus de séchage (1).
PCT/FI2017/050580 2016-08-18 2017-08-18 Procédé et agencement pour la recirculation d'air dans un processus de séchage WO2018033665A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE112017004101.5T DE112017004101B4 (de) 2016-08-18 2017-08-18 Verfahren und Anordnung zum Rezirkulieren einer Luft in einem Trocknungsprozess

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20165617A FI128437B (en) 2016-08-18 2016-08-18 A method and an arrangement for recirculating air in a drying process
FI20165617 2016-08-18

Publications (1)

Publication Number Publication Date
WO2018033665A1 true WO2018033665A1 (fr) 2018-02-22

Family

ID=59761993

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2017/050580 WO2018033665A1 (fr) 2016-08-18 2017-08-18 Procédé et agencement pour la recirculation d'air dans un processus de séchage

Country Status (4)

Country Link
CN (2) CN107764035A (fr)
DE (1) DE112017004101B4 (fr)
FI (1) FI128437B (fr)
WO (1) WO2018033665A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020079326A1 (fr) * 2018-10-17 2020-04-23 Tm System Finland Oy Système et procédé de recirculation d'air pour une sécherie de machine à papier ou à carton
EP3807065A1 (fr) * 2018-06-13 2021-04-21 Raute Oyj Système de conditionnement pour le traitement du bois et procédé associé
EP3794296A4 (fr) * 2018-05-17 2021-08-04 TM System Finland Oy Agencement et procédé permettant de conditionner de l'air d'échappement humide
DE102021101998A1 (de) 2021-01-28 2022-07-28 Voith Patent Gmbh Verfahren zur Entschwadung von Prozessabluft

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5215670A (en) * 1990-02-26 1993-06-01 Bio Gro Systems, Inc. Process of drying and pelletizing sludge in indirect dryer having recycled sweep air
US5775004A (en) * 1995-09-27 1998-07-07 Andritz-Patentverwaltungs-Gesellschaft M.B.H. Process and apparatus for drying a solid-liquid mixture
WO1998056986A1 (fr) * 1997-05-30 1998-12-17 Valmet Corporation Procede et systeme de recuperation de la chaleur de l'air d'evacuation provenant d'un systeme a vide d'une machine a papier ou d'un systeme analogue
WO2000044475A1 (fr) * 1999-01-28 2000-08-03 Sirven Procede et installation pour l'epuration chimique de la vapeur dans un deshydrateur a compression mecanique de la vapeur
CN203421932U (zh) * 2013-09-02 2014-02-05 唐山市协力选煤干燥科技有限公司 一种干燥废气净化循环利用系统

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6370797B1 (en) * 1998-06-11 2002-04-16 Universal Dynamics, Inc. Method and apparatus for drying granular solids with venturi powered gas circulation
SG83158A1 (en) * 1998-12-12 2001-09-18 Univ Singapore A modular heat pump system for drying and air-conditioning
JP4481893B2 (ja) * 2005-07-08 2010-06-16 株式会社グリーンセイジュ 乾燥システム
US10260761B2 (en) * 2010-05-18 2019-04-16 Energy & Environmental Research Center Foundation Heat dissipation systems with hygroscopic working fluid
ES2666420T3 (es) * 2013-02-11 2018-05-04 Fluidic, Inc. Sistema de recaptura/reciclado de agua en celdas electroquimicas
CN105579804A (zh) * 2013-07-29 2016-05-11 能源及环境研究中心基金会 具有吸湿性工作流体的散热系统
CN103822444A (zh) * 2014-03-17 2014-05-28 苏文先 回流除湿式节能干物系统
CN103983088A (zh) * 2014-05-20 2014-08-13 西安热工研究院有限公司 一种利用电站废热预干燥褐煤及水分回收的系统和方法
CN103990351B (zh) * 2014-05-31 2016-05-25 蔡博 一种挥发性有机废气的净化回收装置
CN107525351B (zh) * 2016-02-22 2019-08-30 长乐市丽智产品设计有限公司 一种干燥机

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5215670A (en) * 1990-02-26 1993-06-01 Bio Gro Systems, Inc. Process of drying and pelletizing sludge in indirect dryer having recycled sweep air
US5775004A (en) * 1995-09-27 1998-07-07 Andritz-Patentverwaltungs-Gesellschaft M.B.H. Process and apparatus for drying a solid-liquid mixture
WO1998056986A1 (fr) * 1997-05-30 1998-12-17 Valmet Corporation Procede et systeme de recuperation de la chaleur de l'air d'evacuation provenant d'un systeme a vide d'une machine a papier ou d'un systeme analogue
WO2000044475A1 (fr) * 1999-01-28 2000-08-03 Sirven Procede et installation pour l'epuration chimique de la vapeur dans un deshydrateur a compression mecanique de la vapeur
CN203421932U (zh) * 2013-09-02 2014-02-05 唐山市协力选煤干燥科技有限公司 一种干燥废气净化循环利用系统

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3794296A4 (fr) * 2018-05-17 2021-08-04 TM System Finland Oy Agencement et procédé permettant de conditionner de l'air d'échappement humide
EP3807065A1 (fr) * 2018-06-13 2021-04-21 Raute Oyj Système de conditionnement pour le traitement du bois et procédé associé
US12202168B2 (en) 2018-06-13 2025-01-21 Raute Oyj Conditioning system for wood processing and a method thereto
WO2020079326A1 (fr) * 2018-10-17 2020-04-23 Tm System Finland Oy Système et procédé de recirculation d'air pour une sécherie de machine à papier ou à carton
DE102021101998A1 (de) 2021-01-28 2022-07-28 Voith Patent Gmbh Verfahren zur Entschwadung von Prozessabluft

Also Published As

Publication number Publication date
CN107764035A (zh) 2018-03-06
FI128437B (en) 2020-05-15
DE112017004101B4 (de) 2024-02-15
CN107764037B (zh) 2020-10-30
DE112017004101T5 (de) 2019-05-02
CN107764037A (zh) 2018-03-06
FI20165617A7 (fi) 2018-02-19

Similar Documents

Publication Publication Date Title
CN108837662B (zh) 一种炭黑干燥炉烟气脱白装置及工艺
CN205379793U (zh) 一种烟气脱硫除尘装置
CN107764037B (zh) 用于在干燥工艺中对空气进行再循环的方法和布置
FI67030B (fi) Foerfarande och anordning foer rening av gaser innehaollandefasta och gasformiga foeroreningar
CN110152460B (zh) 一种利用烟囱套筒节水消白烟装置及方法
CN110567290B (zh) 一种非饱和高湿尾气消白烟装置及方法
JP4778403B2 (ja) Ｖｏｃ含有排ガス中からｖｏｃを回収濃縮し、排ガスを浄化する方法および装置。
CN101228398B (zh) 冷却空气流的方法
KR20160000900A (ko) 백연저감 열교환기의 응축수 회수장치
SE425219B (sv) Sett och anordning att rena en forsmutsad gas, exempelvis procrssfranluft, och att dervid styra temperaturen och relativa fuktigheten
KR20100118207A (ko) 냉각탑
KR20050025291A (ko) 수냉식 백연 제거방법 및 장치
CN214270654U (zh) 一种带有喷淋除尘功能的污泥干化装置
CN108686468A (zh) 烟羽脱白的系统和工艺
CN210905523U (zh) 一种烟气除湿装置
KR101580679B1 (ko) 슬러지 건조기용 폐열 회수장치
JPH10113530A (ja) パン焼きプラント及び他のプラントのエミッションからの水溶性で揮発性の有機化合物の回収
CN107715624A (zh) 集污染物清洗过滤与蒸发冷却于一体的燃气轮机进气处理方法
CN110500877B (zh) 用于调节潮湿排气的结构和方法
CN114130168B (zh) 多级除湿装置、废气处理系统及除湿控制方法
WO2022035385A1 (fr) Climatiseur
CN212974706U (zh) 一种模块化卧式脱硫设备系统
GB2092909A (en) Process and system for elimination of paint solvent vapours
JPH0663335A (ja) 排気除害システム
CN211425104U (zh) 一种非饱和高湿尾气消白烟装置

Legal Events

Date Code Title Description
DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17761302

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 17761302

Country of ref document: EP

Kind code of ref document: A1

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载