WO2006024696A1 - A dryer and a method for using and manufacturing thereof - Google Patents

A dryer and a method for using and manufacturing thereof Download PDF

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Publication number
WO2006024696A1
WO2006024696A1 PCT/FI2005/050300 FI2005050300W WO2006024696A1 WO 2006024696 A1 WO2006024696 A1 WO 2006024696A1 FI 2005050300 W FI2005050300 W FI 2005050300W WO 2006024696 A1 WO2006024696 A1 WO 2006024696A1
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WO
WIPO (PCT)
Prior art keywords
gas
drying
dryer
unit
drying vessel
Prior art date
Application number
PCT/FI2005/050300
Other languages
French (fr)
Inventor
Heimo Välimäki
Original Assignee
Vaelimaeki Heimo
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 Vaelimaeki Heimo filed Critical Vaelimaeki Heimo
Priority to EP05775186.9A priority Critical patent/EP1800077A4/en
Publication of WO2006024696A1 publication Critical patent/WO2006024696A1/en

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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
    • F26B21/02—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
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/18—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs
    • F26B17/20—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/18—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs
    • F26B17/20—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined
    • F26B17/205—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined with multiple chambers, e.g. troughs, in superimposed arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/041—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying flowable materials, e.g. suspensions, bulk goods, in a continuous operation, e.g. with locks or other air tight arrangements for charging/discharging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
    • F26B2200/18—Sludges, e.g. sewage, waste, industrial processes, cooling towers

Definitions

  • the invention relates to a dryer for drying liquid and slurry-like materials, said dryer comprising a drying vessel, a material supply unit and a material removal unit.
  • the invention also relates to a method for using and manufacturing the dryer.
  • Liquid and slurry-like material is usually dried in drying vessels by means of a shell connected to the vessel. Hot water or steam, for example, can be led to the shell.
  • the target in drying is to heat the material to such dryness that it boils off water from itself at the applied pressure.
  • Methods are also known, in which steam is led to be mixed with the material contained in the drying vessel for heating and partially drying it.
  • a central problem in the dryers is soiling of heat transmission surfaces and low heat transmission due to which they require a large heat transmission surface.
  • dryers employing steam can be efficient, but on the other hand, their energy consumption can be very high.
  • a dryer has now been invented, which is very efficient and the energy consumption of which is extremely low.
  • a special advantage is also that it is very efficient compared to its size.
  • the dryer according to the invention includes a gas supply unit and a gas exhaust unit, and connected to the gas exhaust unit there is a vacuum pump for generating a vacuum and for removing the exhaust gas generating during drying, and connected to the gas exhaust unit and the drying vessel and to between the gas exhaust unit and the gas supply unit there are a circulating fan and a circulated gas superheater for superheating the exhaust gas generating during drying and for circulating it back to the drying vessel.
  • a mixer for mixing the material to be dried. This can be used to partially enhance the drying.
  • the drying surface can be made larger and it is possible to obtain a desired type of material, e.g. powdery, depending on the mixer design.
  • the structure of the material can be influenced by the mixer design and mixing power.
  • the dryer according to the invention is essentially impermeable to gas.
  • external air must not be allowed to enter the process.
  • a mechanical seal is advantageously used as the shaft seal for the fan.
  • a mechanical seal can advantageously be used in the possible mixer of the drying vessel as well.
  • the sealing agent can advantageously be liquid or steam.
  • a dust separator is connected to the gas exhaust unit for separating dust from the exhaust gas. This can be used to remove any dust emissions, which may be carried along with steam or non- condensing gases in certain conditions.
  • the dust separator can be an updraught chamber, filter bag, or a water shower, for example. It can be composed of one or more units.
  • the dust separator chamber is advantageously formed by the gas exhaust unit. This provides structural and functional benefits.
  • the gas temperature is increased by circulating the gas via the superheater to such a high level that the desired drying condition is achieved. Additional steam may be required approximately for the amount of the evaporating energy. Energy is not essentially consumed e.g. for increasing the superheating temperature, because, besides the consumption of evaporating energy, the steam temperature does not otherwise decrease in the drying vessel, and the circulating fan, for example, increases the steam temperature.
  • the chamber does not contain oxygen, there is no risk of explosion or oxidation risk for the product. Due to the long heat treatment time, the product is hygienically of a high quality.
  • Heat transmission in this type of dryer is very efficient, as the energy difference (remainder of in-going and out-going steam) of the superheated aqueous steam can be directly transferred to the material to be dried. At the same time, the energy of aqueous steam evaporating from the dried material can be very efficiently recovered.
  • Using steam in the dryer is particularly advantageous compared to the use of air.
  • the heat transfer capability of air is poor; in fact, in the technical sense, air is an insulator. Air itself cannot be condensed and only the moisture contained in it can be removed. In addition, air is heavier (1.2 kg/m3) than aqueous steam at the corresponding pressure (0.6 kg/m3), in which case air picks up material to be dried more easily as dust into the circulation. Furthermore, the gas (aqueous steam) led out from the process can be condensed. Condensation of water generally requires the same amount of energy independent of the exhaust gas, while heat can be recovered from steam remarkably more efficiently than from air.
  • the energy consumption of the dryer is very low, since in practice the whole heat content can often be recovered from the removing energy at a temperature only approx. 2°C lower than the temperature corresponding to the pressure in the drying chamber.
  • the temperature of the recovered water is approx. 90 0 C, and in that case the supply temperature of water used in the process can be 0-70 0 C.
  • it is possible to obtain relatively warm cooling water which can advantageously be utilized e.g. in the district heat production or for preheating boiler supply water.
  • the shape of the drying vessel of the equipment according to the invention can vary freely.
  • it is cylindrical.
  • a cylindrical vessel is easy to manufacture and allows using even very low drying pressures.
  • a particularly advantageous shape for the drying vessel is a horizontal cylinder, since this shape is technically favorable for connecting the parts and functions required by the process.
  • the number of material supply units, material removal units, gas supply units and gas exhaust units can be one or more depending on the application. It is possible, for example, to manufacture a dryer that has separate units for circulating and removing the exhaust gas. Gas removal and circulation can in some cases be advantageously connected. Connecting is beneficial in case the equipment is fitted with a dust separator that is used for treating both the exhaust gas to be removed and the exhaust gas to be circulated.
  • the dryer can be advantageously used e.g. for drying liquid and slurry-like materials to a dry powder with the water content below 10%, advantageously such as 2-5%.
  • the process can be controlled very advantageously by means of the pressure value and flow volume.
  • the pressure and the flow can be independently controlled for finding an optimum drying condition for each material and for each supply volume.
  • the drying equipment can be batch-operated or continuous or a combination of these.
  • the equipment and the method can advantageously be adapted to very many different applications.
  • the process method to be selected depends on the material to be dried; batch-type drying can advantageously be used e.g. in drying meat products and vegetables, while for drying of slurries, lignin, grain and process pulps, the use of continuous or semi-continuous equipment is advantageous.
  • a heat exchanger is connected to the drying vessel for heating the drying vessel and the material to be dried. This can be used to partially enhance drying e.g. at the feeding point or at the beginning of the batch process.
  • the equipment is provided with a separate preheater for preheating the suspension to be supplied.
  • This application can be more advantageous and efficient for some materials than a heat exchanger connected to the drying vessel.
  • the preheater functions simultaneously as a dust separator.
  • the wet input binds dust, especially if the input is advantageously mixed with a mixer.
  • Exhaust gas can advantageously be led to the heater, which allows recovering efficiently its heat in the process itself.
  • a condenser is connected to the gas exhaust unit for condensing aqueous steam from the exhaust gas. This enhances condensing.
  • a separate condenser enables separating the condensate. This provides the benefit that any impurities in water can be advantageously separated.
  • the condenser can be simultaneously used to control the process.
  • the pressure in the drying vessel can advantageously be dropped e.g. by raising the outlet gas amount by increasing the coolant flow in the condenser.
  • the equipment operates as an independent unit and does not discharge anything else except the removed water as condensate and the non-condensing gases via the vacuum pump. In this way no load is caused to the environment.
  • a so called surface condenser or a mixing condenser can be used as the condenser.
  • a mixing condenser is advantageous, if the product is fluffy or if it is desired to make the cooling water discharge as hot as possible for the heat recovery.
  • a surface condenser can be used e.g. at high pressures or when an easily controllable cooling is desired.
  • Condensate condensed from the product is recirculated in the mixing condenser. Its temperature can be reduced using a heat exchanger connected to the circulation, which can be used to recover the heat to a desired liquid. Extra condensate entering the circulation is removed from the circuit.
  • the vacuum pump functions as the condenser.
  • An annular water pump can advantageously be used as this pump. This is particularly beneficial e.g. in small applications or when aiming at equipment solutions that are as simple and compact as possible.
  • aqueous steam condenses in water and non-condensing gases are removed via the gas exhaust unit.
  • Drying materials can be characterized by 5 different states while drying aqueous slurry into a powder:
  • the powder dries up and certain products may exhibit slight dusting, which can advantageously be reduced with a small water shower. Then the amount of water can be for example 5-25% of the vaporization efficiency ("dusting stage"). It has been shown that the dry dust-like powder of the dryer does not attach to the hot heat surface of the superheater. It does not attach to the fan or the channels either. Dust can be bound during drying using also other methods.
  • the product can be removed from the dryer periodically, for example.
  • the chamber can be advantageously pressurized essentially to equal pressure with the external air. In this way the discharge can be easily carried out.
  • all powder is advantageously not removed from the dryer, but the driest part, for example, from the outlet end of the dryer. It is also possible to dry the whole batch and remove a part of it after which slurry is added to the powder making in this way the powder contained in the dryer moisten again to the "grain stage".
  • the chamber can be pressurized with saturated aqueous steam or air or a mixture of these.
  • the discharge can be carried out at intervals of 1-24 hours, for example.
  • the amount of required compensating gas is relatively small.
  • air is allowed to enter into the mixing condenser, it is advantageously removed from it quickly with the evaporating steam without disturbing the process.
  • the material supply unit and the material removal unit of one embodiment of the invention are located essentially at the opposite ends of the drying vessel. This technical solution provides the suspension to be dried with a relatively long dwelling time and ensures efficient drying of the entire suspension.
  • the material supply unit and the gas exhaust unit are located essentially at the same end of the drying vessel. This can enhance the contact between the gas and the suspension to be dried and improve the drying efficiency.
  • the superheated circulating gas flows against the product flow. In this way any fine fractions, i.e. dust, detaching from the product are transferred backwards towards the wetter product and the previous drying vessel.
  • the material removal unit and the gas exhaust unit are located essentially at the opposite ends of the drying vessel.
  • This technical solution is advantageous when drying for example a product that dusts relatively more in the dry state, in which case gas removal takes place at the wet and less dusting point of the drying vessel.
  • the material removal unit and the gas exhaust unit are located essentially at the same end of the drying vessel.
  • This technical solution is advantageous when drying for example a product that is sticky in the dry state, in which case gas removal takes place at a less dusting point of the drying vessel.
  • gas removal takes place at a less dusting point of the drying vessel.
  • a product that is dust-like in the wet state for example after filtering, and sticky in the dry state, such as tar-like
  • Such sticky material efficiently makes dust adhere to itself.
  • the pressure generated in the drying vessel and the exhaust gas unit is 200 mbar or lower.
  • the heat effect can be kept minimal for example when drying heat-sensitive products.
  • the use of a low pressure is advantageous also when drying can be carried out with a relatively low heating capacity.
  • the circulating fan is a centrifugal fan.
  • a centrifugal fan can be used to circulate even large amounts of gas, if required.
  • a centrifugal fan can be adjusted in a wide range without reaching the cavitation area.
  • a centrifugal fan can advantageously be adjusted with rpm control, in which case it is easily adaptable to varying conditions, and the equipment is at the same time simple to automatize.
  • the dryer includes two or more dryers for drying the outlet suspension.
  • the material supply unit, the material removal unit, the gas supply unit and/or the gas exhaust unit of the drying vessel are composed of one or more intermediate units located between two drying vessels. This provides particular structural benefits when connecting together two or more drying vessels. In some cases, this provides functional benefits as well, as the contact between the material to be dried and the drying gas can in this case be essentially improved.
  • two or more dryers are connected in series such that the material removal unit of one dryer is connected to the material supply unit and/or as the material supply unit of the other dryer.
  • drying vessels are used in a continuously operating superheater-dryer to make sure that the product flow is as uniform as possible.
  • These chambers can advantageously be relatively narrow or long in shape.
  • the material to be dried, such as slurry or aqueous suspension, is transferred, advantageously drops, from one part to another and finally out.
  • the pressure of the dryer is varied during drying.
  • the pressure in the gas space of the drying vessel can advantageously be adjusted according to the properties of the material to be dried.
  • the pressure of the dryer is decreased during drying. As the drying proceeds, the material becomes dry being more susceptible to become airborne. Decreasing the pressure prevents the dust from becoming airborne. In the batch process this can advantageously be carried out in the final stage of drying. In a continuous process, the pressure is advantageously kept lower at the tail end of the drying vessel, where the material removal unit is located, preventing in this way the material from "taking off' with the evaporating steam at the tail end either.
  • the two or more dryers have different pressures relative to each other. This can be used to optimize the drying in relation to the properties of the material.
  • the pressure and temperature are advantageously higher in the first dryer than in the second dryer.
  • the product can be advantageously taken out of the equipment through a pressure balancing unit, such as a chamber, for adjusting the outlet pressure of the suspension.
  • the pressure balancing unit can have positive or negative pressure.
  • steam is led to the pressure balancing unit before discharging and the pressure is then balanced according to the environmental pressure.
  • the removal of suspension is as uniform as possible and on the other hand, air is not allowed to enter the drying vessel, which would impair the operation of the dryer at least temporarily.
  • the dryer is used for drying an aqueous material and a slurry-like material, such as a raw material, a semi-finished product, a product and/or waste.
  • Such materials can comprise e.g. waste water slurry, a protein product, meat, mushrooms, fruit, berries, grain products, offal, organic suspensions, wood pulps and inorganic suspensions.
  • Figure 1 illustrates a one-stage dryer.
  • FIG. 1 illustrates drying equipment with two dryers connected in series.
  • Figure 3 illustrates a double-chamber dryer
  • Figure 4 illustrates a 3-part continuously-operating dryer.
  • Figure 1 shows a dryer 20 with a drying vessel 1 , to which a material supply unit 10 and a material removal unit 9 are connected.
  • a gas supply unit 4 and a gas exhaust unit 6 are connected to the drying vessel.
  • a vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum, and a circulating fan 2 and a circulated gas superheater 3 are connected to the gas exhaust unit 6 and the drying vessel 1 and to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the low-pressure exhaust gas 18 discharging from the drying vessel 1 and for circulating it back to the drying vessel 1.
  • Saturated aqueous steam 11 or hot water or oil, for example, is supplied to the superheater 3.
  • a condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12.
  • the drying vessel 1 also comprises a mixer 5 for mixing the material to be dried. It also includes a steam supply unit 16 for heating the suspension, in which case the saturated steam is superheated with the superheater 3, as well as a heat exchanger 14 for heating the suspension and the drying vessel 1. As the heating agent 15, steam or hot water can be used.
  • FIG 2 shows drying equipment, in which there are two dryers according to Figure 1 connected in series such that the material removal unit 9 of one dryer 20 is connected to the material supply unit 10 of the other dryer 20.
  • Figure 3 illustrates 2-stage drying equipment 20 having two drying vessels 1a, 1b. Connected to the first drying vessel 1a there are a material supply unit 10, a heat exchanger 14 and a gas exhaust unit 6, and connected to the second drying vessel 1b there are a material removal unit 9 and a gas supply unit 4.
  • a vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum.
  • a dust separator chamber 17 is connected to the gas exhaust unit 6.
  • a circulating fan 2 and a tube heat exchanger 3 are connected to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the exhaust gas removing from the first drying vessel 1a and for circulating it back to the second drying vessel 1b.
  • Saturated aqueous steam 11 or hot water for example, is supplied to the superheater 3.
  • the steam condensate 15 of the superheater is led to the heat exchanger 14 of the first drying vessel.
  • Saturated aqueous steam 11 can also be led directly to it for heating the first drying vessel 1a and the suspension. It is possible to lead also water W to the first drying vessel 1a for binding the dust of the exhaust gas 18.
  • a mixing condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12.
  • the drying vessels 1a, 1b also comprise a mixer 5 for mixing the material to be dried. From the mixing condenser 7 the condensate 25 is led to the heat recovery exchanger 22 for heating the heating water 23. Cooled condensate 25 is led to the balancing tank 24, from which extra condensate 25 is removed and a part is circulated to the mixing condenser 7.
  • the running method was a continuous supply for approx. 22 hours with the dryer suspension in the "grain stage” and removal of the dried material in batches.
  • the supply took place in the breaking stage at a pressure of 815 mbara and the discharge after the dusting stage at a pressure of approx. 200 mbara, when the powder has had time to cool down at a low pressure.
  • the discharge itself was carried out at the atmospheric pressure by filling for example with steam (50 m 3 - 30 kg of steam). In this case any steam moisture cools the powder even more when evaporating from the powder surface. Since the chamber does not contain oxygen, there is no risk of explosion or oxidation risk for the product. Due to the long heat treatment time, the product is hygienically of a high quality.
  • Figure 4 illustrates continuously-operating drying equipment having three drying vessels 1c, 1d, 1e for distributing the product flow evenly.
  • a material supply unit 10 and a gas exhaust unit 6 Connected to the first drying vessel 1c there are a material supply unit 10 and a gas exhaust unit 6, and connected to the third drying vessel 1e there are a material removal unit 9 and a gas supply unit 4.
  • a vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum.
  • the dust separator chamber 17 is formed by the gas removal unit 6.
  • a circulating fan 2 and a tube heat exchanger 3 are connected to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the exhaust gas 18 generating in the first drying vessel 1a and for circulating it back to the third drying vessel 1e.
  • drying vessels 1c, 1d, 1e Disposed between the drying vessels 1c, 1d, 1e there are intermediate units 21 for leading the suspension to be dried and the exhaust gas 18. Saturated aqueous steam 11 is supplied to the superheater 3. To the first drying vessel 1c, it is also possible to lead water W for binding the dust of the exhaust gas 18 and/or for adjusting the pressure of the vessels 1c, 1d, 1e.
  • a mixing condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12.
  • the drying vessels 1c, 1d, 1e also comprise a mixer 5 for mixing the material to be dried. From the mixing condenser 7 the condensate 25 is led to the heat recovery exchanger 22 for heating the heating water 23.
  • Cooled condensate 25 is led to the balancing tank 24, from which extra condensate 25 is removed and a part is circulated to the mixing condenser 7.
  • a pressure balancing chamber 26 is connected to the material removal unit 9 for adjusting the pressure of the suspension removal. The dried product is taken out from the equipment 20 via the pressure balancing chamber 26.
  • the pressure balancing chamber can have positive or negative pressure.
  • Steam 28 is led to the pressure balancing unit 26 before discharging and the pressure is then balanced according to the environmental pressure by means of the balancing unit 27.
  • a connecting balancing unit 29 is used to balance the pressures in the pressure balancing chamber 26 and in the 3rd drying vessel 1e.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Molecular Biology (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

The invention relates to a dryer for drying an aqueous material. The invention also relates to a method for using the dryer and a method for manufacturing thereof. The dryer (20) according to the invention comprises a drying vessel (1 , 1 a-1e), a material supply unit (10) and a material removal unit (9). The dryer (20) includes a gas supply unit (4) and a gas exhaust unit (6), and connected to the gas exhaust unit (6) there is a vacuum pump (8) for generating a vacuum and for removing the exhaust gas (18) generating in drying from the drying vessel (1 , 1a-1e) and that a circulating fan (2) and a circulated gas superheater (3) are connected to the gas exhaust unit (6) and the drying vessel (1 , 1a-1e) and to between the gas exhaust unit (6) and the gas supply unit (4) for superheating the removing low-pressure exhaust gas (18) and for circulating it back to the drying vessel (1 , 1a-1e), and the dryer (20) is essentially impermeable to gas, and connected to the drying vessel (1 , 1a-1e) there is a mixer (5) for mixing the material to be dried.

Description

A dryer and a method for using and manufacturing thereof
Technical background
The invention relates to a dryer for drying liquid and slurry-like materials, said dryer comprising a drying vessel, a material supply unit and a material removal unit. The invention also relates to a method for using and manufacturing the dryer.
Liquid and slurry-like material is usually dried in drying vessels by means of a shell connected to the vessel. Hot water or steam, for example, can be led to the shell. The target in drying is to heat the material to such dryness that it boils off water from itself at the applied pressure. Methods are also known, in which steam is led to be mixed with the material contained in the drying vessel for heating and partially drying it.
A central problem in the dryers is soiling of heat transmission surfaces and low heat transmission due to which they require a large heat transmission surface. On one hand, dryers employing steam can be efficient, but on the other hand, their energy consumption can be very high.
General description of invention
A dryer has now been invented, which is very efficient and the energy consumption of which is extremely low. A special advantage is also that it is very efficient compared to its size.
To achieve this object, the invention is characterized by the features specified in the independent claims. Some of the advantageous embodiments of the invention are set forth in the other claims.
The dryer according to the invention includes a gas supply unit and a gas exhaust unit, and connected to the gas exhaust unit there is a vacuum pump for generating a vacuum and for removing the exhaust gas generating during drying, and connected to the gas exhaust unit and the drying vessel and to between the gas exhaust unit and the gas supply unit there are a circulating fan and a circulated gas superheater for superheating the exhaust gas generating during drying and for circulating it back to the drying vessel. Connected to the drying vessel there is a mixer for mixing the material to be dried. This can be used to partially enhance the drying. The drying surface can be made larger and it is possible to obtain a desired type of material, e.g. powdery, depending on the mixer design. The structure of the material can be influenced by the mixer design and mixing power.
The dryer according to the invention is essentially impermeable to gas. For optimizing drying, external air must not be allowed to enter the process. A mechanical seal is advantageously used as the shaft seal for the fan. A mechanical seal can advantageously be used in the possible mixer of the drying vessel as well. The sealing agent can advantageously be liquid or steam.
According to one embodiment of the invention, a dust separator is connected to the gas exhaust unit for separating dust from the exhaust gas. This can be used to remove any dust emissions, which may be carried along with steam or non- condensing gases in certain conditions. The dust separator can be an updraught chamber, filter bag, or a water shower, for example. It can be composed of one or more units. The dust separator chamber is advantageously formed by the gas exhaust unit. This provides structural and functional benefits.
In the dryer according to the invention, the gas temperature is increased by circulating the gas via the superheater to such a high level that the desired drying condition is achieved. Additional steam may be required approximately for the amount of the evaporating energy. Energy is not essentially consumed e.g. for increasing the superheating temperature, because, besides the consumption of evaporating energy, the steam temperature does not otherwise decrease in the drying vessel, and the circulating fan, for example, increases the steam temperature.
Since the chamber does not contain oxygen, there is no risk of explosion or oxidation risk for the product. Due to the long heat treatment time, the product is hygienically of a high quality.
When the amount of gas evaporated from the circulating product increases, the pressure in the vessel rises, if the extra evaporated gas is not condensed from the drying vessel.
Heat transmission in this type of dryer is very efficient, as the energy difference (remainder of in-going and out-going steam) of the superheated aqueous steam can be directly transferred to the material to be dried. At the same time, the energy of aqueous steam evaporating from the dried material can be very efficiently recovered.
Using steam in the dryer is particularly advantageous compared to the use of air. The heat transfer capability of air is poor; in fact, in the technical sense, air is an insulator. Air itself cannot be condensed and only the moisture contained in it can be removed. In addition, air is heavier (1.2 kg/m3) than aqueous steam at the corresponding pressure (0.6 kg/m3), in which case air picks up material to be dried more easily as dust into the circulation. Furthermore, the gas (aqueous steam) led out from the process can be condensed. Condensation of water generally requires the same amount of energy independent of the exhaust gas, while heat can be recovered from steam remarkably more efficiently than from air.
The energy consumption of the dryer is very low, since in practice the whole heat content can often be recovered from the removing energy at a temperature only approx. 2°C lower than the temperature corresponding to the pressure in the drying chamber. For example, if the drying pressure of the chamber is 756 mbar, the temperature of the recovered water is approx. 900C, and in that case the supply temperature of water used in the process can be 0-700C. In this situation it is possible to obtain relatively warm cooling water, which can advantageously be utilized e.g. in the district heat production or for preheating boiler supply water.
The shape of the drying vessel of the equipment according to the invention can vary freely. Advantageously it is cylindrical. A cylindrical vessel is easy to manufacture and allows using even very low drying pressures. A particularly advantageous shape for the drying vessel is a horizontal cylinder, since this shape is technically favorable for connecting the parts and functions required by the process.
The number of material supply units, material removal units, gas supply units and gas exhaust units can be one or more depending on the application. It is possible, for example, to manufacture a dryer that has separate units for circulating and removing the exhaust gas. Gas removal and circulation can in some cases be advantageously connected. Connecting is beneficial in case the equipment is fitted with a dust separator that is used for treating both the exhaust gas to be removed and the exhaust gas to be circulated. The dryer can be advantageously used e.g. for drying liquid and slurry-like materials to a dry powder with the water content below 10%, advantageously such as 2-5%.
The process can be controlled very advantageously by means of the pressure value and flow volume. The pressure and the flow can be independently controlled for finding an optimum drying condition for each material and for each supply volume.
The drying equipment can be batch-operated or continuous or a combination of these. In this case the equipment and the method can advantageously be adapted to very many different applications. The process method to be selected depends on the material to be dried; batch-type drying can advantageously be used e.g. in drying meat products and vegetables, while for drying of slurries, lignin, grain and process pulps, the use of continuous or semi-continuous equipment is advantageous.
According to one embodiment of the invention, a heat exchanger is connected to the drying vessel for heating the drying vessel and the material to be dried. This can be used to partially enhance drying e.g. at the feeding point or at the beginning of the batch process.
According to one embodiment of the invention, the equipment is provided with a separate preheater for preheating the suspension to be supplied. This application can be more advantageous and efficient for some materials than a heat exchanger connected to the drying vessel.
According to one embodiment of the invention, the preheater functions simultaneously as a dust separator. In this case the wet input binds dust, especially if the input is advantageously mixed with a mixer.
Exhaust gas can advantageously be led to the heater, which allows recovering efficiently its heat in the process itself.
Advantageously, it is also possible to connect a direct steam supply to the drying vessel for heating the suspension and the equipment.
According to one embodiment of the invention, a condenser is connected to the gas exhaust unit for condensing aqueous steam from the exhaust gas. This enhances condensing. A separate condenser enables separating the condensate. This provides the benefit that any impurities in water can be advantageously separated. The condenser can be simultaneously used to control the process. The pressure in the drying vessel can advantageously be dropped e.g. by raising the outlet gas amount by increasing the coolant flow in the condenser.
The equipment operates as an independent unit and does not discharge anything else except the removed water as condensate and the non-condensing gases via the vacuum pump. In this way no load is caused to the environment.
A so called surface condenser or a mixing condenser can be used as the condenser. A mixing condenser is advantageous, if the product is fluffy or if it is desired to make the cooling water discharge as hot as possible for the heat recovery. A surface condenser can be used e.g. at high pressures or when an easily controllable cooling is desired.
Condensate condensed from the product is recirculated in the mixing condenser. Its temperature can be reduced using a heat exchanger connected to the circulation, which can be used to recover the heat to a desired liquid. Extra condensate entering the circulation is removed from the circuit.
According to one embodiment of the invention, the vacuum pump functions as the condenser. An annular water pump can advantageously be used as this pump. This is particularly beneficial e.g. in small applications or when aiming at equipment solutions that are as simple and compact as possible. In an annular water pump aqueous steam condenses in water and non-condensing gases are removed via the gas exhaust unit.
Drying materials can be characterized by 5 different states while drying aqueous slurry into a powder:
- In the initial stage the slurry is hot and like hot chocolate ("chocolate stage")
- In the second stage the slurry begins to roll up into rolls and balls ("ball stage")
- In the third stage the rolls and balls start breaking ("breaking stage")
- In the fourth stage the broken suspension resembles the earth's wet, block- like, rough, separate grain, which does not dust ("grain stage")
- In the fifth stage the powder dries up and certain products may exhibit slight dusting, which can advantageously be reduced with a small water shower. Then the amount of water can be for example 5-25% of the vaporization efficiency ("dusting stage"). It has been shown that the dry dust-like powder of the dryer does not attach to the hot heat surface of the superheater. It does not attach to the fan or the channels either. Dust can be bound during drying using also other methods.
When the powder is in the fourth stage ("grain stage"), it is advantageous to add new slurry to be dried in it either from the supply unit or the preheater. It is advantageous to keep the slurry in this "grain stage" for the entire drying event.
It is often advantageous to feed the equipment almost continually such that the suspension to be dried is in the "grain stage".
The product can be removed from the dryer periodically, for example. In the discharge stage the chamber can be advantageously pressurized essentially to equal pressure with the external air. In this way the discharge can be easily carried out. In the discharge stage, all powder is advantageously not removed from the dryer, but the driest part, for example, from the outlet end of the dryer. It is also possible to dry the whole batch and remove a part of it after which slurry is added to the powder making in this way the powder contained in the dryer moisten again to the "grain stage". The chamber can be pressurized with saturated aqueous steam or air or a mixture of these. The discharge can be carried out at intervals of 1-24 hours, for example. When using a pressure near to the atmospheric pressure, the amount of required compensating gas is relatively small. When air is allowed to enter into the mixing condenser, it is advantageously removed from it quickly with the evaporating steam without disturbing the process.
When it is desired to destroy bacteria and similar contained in the suspension, it is advantageous to use a long heat treatment time and/or a high pressure in the process as a batch-type or continuous process. Similarly, when it is desired to have a reduced heat treatment, a low boiling pressure is used as a batch-type run.
The material supply unit and the material removal unit of one embodiment of the invention are located essentially at the opposite ends of the drying vessel. This technical solution provides the suspension to be dried with a relatively long dwelling time and ensures efficient drying of the entire suspension.
According to one embodiment of the invention, the material supply unit and the gas exhaust unit are located essentially at the same end of the drying vessel. This can enhance the contact between the gas and the suspension to be dried and improve the drying efficiency. Advantageously the superheated circulating gas flows against the product flow. In this way any fine fractions, i.e. dust, detaching from the product are transferred backwards towards the wetter product and the previous drying vessel.
According to one embodiment of the invention, the material removal unit and the gas exhaust unit are located essentially at the opposite ends of the drying vessel. This technical solution is advantageous when drying for example a product that dusts relatively more in the dry state, in which case gas removal takes place at the wet and less dusting point of the drying vessel.
According to one embodiment of the invention, the material removal unit and the gas exhaust unit are located essentially at the same end of the drying vessel. This technical solution is advantageous when drying for example a product that is sticky in the dry state, in which case gas removal takes place at a less dusting point of the drying vessel. When drying a product that is dust-like in the wet state, for example after filtering, and sticky in the dry state, such as tar-like, it is advantageous to connect a fan to this dry end. Such sticky material efficiently makes dust adhere to itself.
According to one embodiment of the invention, the pressure generated in the drying vessel and the exhaust gas unit is 200 mbar or lower. In this case the heat effect can be kept minimal for example when drying heat-sensitive products. The use of a low pressure is advantageous also when drying can be carried out with a relatively low heating capacity.
According to one embodiment of the invention, the circulating fan is a centrifugal fan. A centrifugal fan can be used to circulate even large amounts of gas, if required. In addition, a centrifugal fan can be adjusted in a wide range without reaching the cavitation area. Also, a centrifugal fan can advantageously be adjusted with rpm control, in which case it is easily adaptable to varying conditions, and the equipment is at the same time simple to automatize.
According to one embodiment of the invention, the dryer includes two or more dryers for drying the outlet suspension.
According to one embodiment of the invention, the material supply unit, the material removal unit, the gas supply unit and/or the gas exhaust unit of the drying vessel are composed of one or more intermediate units located between two drying vessels. This provides particular structural benefits when connecting together two or more drying vessels. In some cases, this provides functional benefits as well, as the contact between the material to be dried and the drying gas can in this case be essentially improved.
According to one embodiment of the invention, two or more dryers are connected in series such that the material removal unit of one dryer is connected to the material supply unit and/or as the material supply unit of the other dryer.
According to one embodiment of the invention, several drying vessels are used in a continuously operating superheater-dryer to make sure that the product flow is as uniform as possible. These chambers can advantageously be relatively narrow or long in shape. The material to be dried, such as slurry or aqueous suspension, is transferred, advantageously drops, from one part to another and finally out.
According to one embodiment of the invention, the pressure of the dryer is varied during drying. The pressure in the gas space of the drying vessel can advantageously be adjusted according to the properties of the material to be dried.
According to one embodiment of the invention, the pressure of the dryer is decreased during drying. As the drying proceeds, the material becomes dry being more susceptible to become airborne. Decreasing the pressure prevents the dust from becoming airborne. In the batch process this can advantageously be carried out in the final stage of drying. In a continuous process, the pressure is advantageously kept lower at the tail end of the drying vessel, where the material removal unit is located, preventing in this way the material from "taking off' with the evaporating steam at the tail end either.
According to one embodiment of the invention, the two or more dryers have different pressures relative to each other. This can be used to optimize the drying in relation to the properties of the material. The pressure and temperature are advantageously higher in the first dryer than in the second dryer.
According to one embodiment of the invention, the product can be advantageously taken out of the equipment through a pressure balancing unit, such as a chamber, for adjusting the outlet pressure of the suspension. The pressure balancing unit can have positive or negative pressure. Advantageously, steam is led to the pressure balancing unit before discharging and the pressure is then balanced according to the environmental pressure. In this case the removal of suspension is as uniform as possible and on the other hand, air is not allowed to enter the drying vessel, which would impair the operation of the dryer at least temporarily. According to the invention, the dryer is used for drying an aqueous material and a slurry-like material, such as a raw material, a semi-finished product, a product and/or waste. Such materials can comprise e.g. waste water slurry, a protein product, meat, mushrooms, fruit, berries, grain products, offal, organic suspensions, wood pulps and inorganic suspensions.
Detailed description of invention
Some of the embodiments of the invention are described below in detail by making reference to the enclosed drawings.
Figure 1 illustrates a one-stage dryer.
Figure 2 illustrates drying equipment with two dryers connected in series.
Figure 3 illustrates a double-chamber dryer.
Figure 4 illustrates a 3-part continuously-operating dryer.
Figure 1 shows a dryer 20 with a drying vessel 1 , to which a material supply unit 10 and a material removal unit 9 are connected. A gas supply unit 4 and a gas exhaust unit 6 are connected to the drying vessel. A vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum, and a circulating fan 2 and a circulated gas superheater 3 are connected to the gas exhaust unit 6 and the drying vessel 1 and to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the low-pressure exhaust gas 18 discharging from the drying vessel 1 and for circulating it back to the drying vessel 1. Saturated aqueous steam 11 or hot water or oil, for example, is supplied to the superheater 3. A condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12. The drying vessel 1 also comprises a mixer 5 for mixing the material to be dried. It also includes a steam supply unit 16 for heating the suspension, in which case the saturated steam is superheated with the superheater 3, as well as a heat exchanger 14 for heating the suspension and the drying vessel 1. As the heating agent 15, steam or hot water can be used.
Figure 2 shows drying equipment, in which there are two dryers according to Figure 1 connected in series such that the material removal unit 9 of one dryer 20 is connected to the material supply unit 10 of the other dryer 20.
Figure 3 illustrates 2-stage drying equipment 20 having two drying vessels 1a, 1b. Connected to the first drying vessel 1a there are a material supply unit 10, a heat exchanger 14 and a gas exhaust unit 6, and connected to the second drying vessel 1b there are a material removal unit 9 and a gas supply unit 4. A vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum. A dust separator chamber 17 is connected to the gas exhaust unit 6. A circulating fan 2 and a tube heat exchanger 3 are connected to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the exhaust gas removing from the first drying vessel 1a and for circulating it back to the second drying vessel 1b. Saturated aqueous steam 11 or hot water, for example, is supplied to the superheater 3. The steam condensate 15 of the superheater is led to the heat exchanger 14 of the first drying vessel. Saturated aqueous steam 11 can also be led directly to it for heating the first drying vessel 1a and the suspension. It is possible to lead also water W to the first drying vessel 1a for binding the dust of the exhaust gas 18. Disposed between the drying vessels 1a, 1b there is an intermediate unit 21 for leading the suspension to be dried and the exhaust gas 18. A mixing condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12. The drying vessels 1a, 1b also comprise a mixer 5 for mixing the material to be dried. From the mixing condenser 7 the condensate 25 is led to the heat recovery exchanger 22 for heating the heating water 23. Cooled condensate 25 is led to the balancing tank 24, from which extra condensate 25 is removed and a part is circulated to the mixing condenser 7.
Below are examples of process parameters for drying a biological slurry with a cylindrical chamber mixer and an updraught chamber separator:
- supplied slurry 10% TS, +200C 2182 kg/h
- saturated steam of superheater 15 bara (14 barg ) +2010C - dryer pressure 815 mbara
- supplied cooling water +600C
- removed cooling water +92°C
- energy recovery 1.5 mW
- saturated steam supply to dryer +1650C - saturated steam outlet from dryer +115°C
- dried powder 90% TS, 242 kg/h
- evaporation power of water 1939 kg H2O
- saturated steam amount approx. 1.2 x 1939 kg/h = 2315 kg/h
- power consumption approx. 120 kW
The running method was a continuous supply for approx. 22 hours with the dryer suspension in the "grain stage" and removal of the dried material in batches. The supply took place in the breaking stage at a pressure of 815 mbara and the discharge after the dusting stage at a pressure of approx. 200 mbara, when the powder has had time to cool down at a low pressure. The discharge itself was carried out at the atmospheric pressure by filling for example with steam (50 m3- 30 kg of steam). In this case any steam moisture cools the powder even more when evaporating from the powder surface. Since the chamber does not contain oxygen, there is no risk of explosion or oxidation risk for the product. Due to the long heat treatment time, the product is hygienically of a high quality.
Figure 4 illustrates continuously-operating drying equipment having three drying vessels 1c, 1d, 1e for distributing the product flow evenly. Connected to the first drying vessel 1c there are a material supply unit 10 and a gas exhaust unit 6, and connected to the third drying vessel 1e there are a material removal unit 9 and a gas supply unit 4. A vacuum pump 8 is connected to the gas exhaust unit 6 for generating a vacuum. The dust separator chamber 17 is formed by the gas removal unit 6. A circulating fan 2 and a tube heat exchanger 3 are connected to between the gas exhaust unit 6 and the gas supply unit 4 for superheating the exhaust gas 18 generating in the first drying vessel 1a and for circulating it back to the third drying vessel 1e. Disposed between the drying vessels 1c, 1d, 1e there are intermediate units 21 for leading the suspension to be dried and the exhaust gas 18. Saturated aqueous steam 11 is supplied to the superheater 3. To the first drying vessel 1c, it is also possible to lead water W for binding the dust of the exhaust gas 18 and/or for adjusting the pressure of the vessels 1c, 1d, 1e. A mixing condenser 7 is connected to the gas exhaust unit 6 for condensing aqueous steam from the exhaust gas 12. The drying vessels 1c, 1d, 1e also comprise a mixer 5 for mixing the material to be dried. From the mixing condenser 7 the condensate 25 is led to the heat recovery exchanger 22 for heating the heating water 23. Cooled condensate 25 is led to the balancing tank 24, from which extra condensate 25 is removed and a part is circulated to the mixing condenser 7. A pressure balancing chamber 26 is connected to the material removal unit 9 for adjusting the pressure of the suspension removal. The dried product is taken out from the equipment 20 via the pressure balancing chamber 26. The pressure balancing chamber can have positive or negative pressure. Steam 28 is led to the pressure balancing unit 26 before discharging and the pressure is then balanced according to the environmental pressure by means of the balancing unit 27. A connecting balancing unit 29 is used to balance the pressures in the pressure balancing chamber 26 and in the 3rd drying vessel 1e.

Claims

Claims
1. A dryer for drying liquid and slurry-like materials, said dryer (20) including a drying vessel (1 , 1a-1e), a material supply unit (10) and a material removal unit (9), characterized in that the dryer (20) includes a gas supply unit (4) and a gas exhaust unit (6), and connected to the gas exhaust unit (6) there is a vacuum pump (8) for generating a vacuum and for removing the exhaust gas (18) generating in drying from the drying vessel (1 , 1a-1e), and that a circulating fan (2) and a circulated gas superheater (3) are connected to the gas exhaust unit (6) and the drying vessel (1 , 1a-1e) and to between the gas exhaust unit (6) and the gas supply unit (4) for superheating the exhaust gas (18) and for circulating it back to the drying vessel (1 , 1a-1e), and the dryer (20) is essentially impermeable to gas, and connected to the drying vessel (1 , 1a-1e) there is a mixer (5) for mixing the material to be dried.
2. A dryer according to claim 1 , characterized in that a dust separator (17) is connected to the gas exhaust unit (6) for separating dust from the exhaust gas
(18).
3. A dryer according to any of the preceding claims, characterized in that a condenser (7) is connected to the gas exhaust unit (6) for condensing aqueous steam from the exhaust gas (18).
4. A dryer according to any of the preceding claims, characterized in that a heat exchanger (14) is connected to the drying vessel (1 , 1a-1e) for heating the drying vessel (1, 1a-1e) and/or the material (K) to be dried.
5. A dryer according to any of the preceding claims, characterized in that the pressure generated in the drying vessel (1 , 1a-1e) and in the exhaust gas (18) is 200 mbar or lower.
6. A dryer according to any of the preceding claims, characterized in that the circulating fan (2) is a centrifugal fan.
7. A dryer according to any of the preceding claims, characterized in that the material supply unit (10) and the material removal unit (9) are located essentially at the opposite ends of the drying vessel (1 , 1 a-1 e).
8. A dryer according to any of the preceding claims, characterized in that the material supply unit (10) and the gas exhaust unit (6) are located essentially at the same end of the drying vessel (1 , 1a-1e).
9. A dryer according to claims 1-8, characterized in that the material removal unit (9) and the gas exhaust unit (6) are located essentially at the same end of the drying vessel (1 , 1a-1e).
10. A dryer according to claims 1-8, characterized in that the material removal unit (9) and the gas exhaust unit (6) are located essentially at the opposite ends of the drying vessel (1 , 1a-1e).
11. A dryer according to any of the preceding claims, characterized in that a pressure balancing chamber (26) is connected to the material removal unit (9) for adjusting the discharge pressure of the suspension.
12. A dryer according to any of the preceding claims, characterized in that it comprises two or more drying vessels (1 , 1a-1e).
13. A dryer according to any of the preceding claims, characterized in that the material supply unit (10), the material removal unit (9), the gas supply unit (4) and/or the gas exhaust unit (6) of the drying vessel (1, 1a-1e) are composed of one or more intermediate units (21) located between two drying vessels (1 , 1a-1e).
14. A dryer according to any of the preceding claims, characterized in that it comprises two or more drying vessels (1, 1a-1e) that are connected in series relative to each other such that the material removal unit (9) of one drying vessel (1 , 1a-1e) is connected to the material supply unit (10) and/or as the material supply unit (10) of the other dryer (20).
15. A method for using a dryer according to claims 12-14, characterized in that the drying vessels (1, 1a-1e) have different pressures relative to each other.
16. A method for using a dryer according to claims 1-14, characterized in that the pressure of the dryer (20) is varied during drying.
17. A method according to claim 16, characterized in that the pressure of the dryer (20) is decreased during drying.
18. A method for using a dryer according to claims 1-14, characterized in that the dryer is used for drying an aqueous material and/or a slurry-like material, a semi-finished product, a product and/or waste, such as juice, a protein product, waste water slurry, meat, mushrooms, fruit, berries, grain products, offal, organic suspension and/or inorganic suspension.
19. A method for manufacturing a dryer, including a drying vessel (1 , 1a-1e), a material supply unit (10) and a material removal unit (9), characterized in that connected to the dryer (20) there are a gas supply unit (4) and a gas exhaust unit
(6), and connected to the gas exhaust unit (6) there is a vacuum pump (8) for generating a vacuum and for removing the exhaust gas (18) generating in drying from the drying vessel (1 , 1a-1e) and that a circulating fan (2) and a circulated gas superheater (3) are connected to the drying vessel (1 , 1a-1e) and to between the gas exhaust unit (6) and the gas supply unit (4) for superheating the generating exhaust gas (18) and for circulating it back to the drying vessel (1 , 1a-
1e), and that connected to the drying vessel (1, 1a-1e) there is a mixer (5) for mixing the material to be dried, and the dryer is made essentially impermeable to gas.
PCT/FI2005/050300 2004-09-03 2005-08-25 A dryer and a method for using and manufacturing thereof WO2006024696A1 (en)

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WO2009010018A1 (en) * 2007-07-16 2009-01-22 Stanislav Tuma Device for drying loose and pasty materials and sludges
WO2009141495A1 (en) 2008-05-20 2009-11-26 St1 Biofuels Oy Method and apparatus for processing waste containing fermentable raw material
FR2947044A1 (en) * 2009-06-23 2010-12-24 Asten Assistance Services Traitements Environnement Nucleaire Device for drying sludge waste containing solvent obtained from treatment industry and cooling towers of nuclear plants, comprises evaporation unit, temperature lowering unit, solvent vapor proof drying enclosure, and transporting unit
FR2947043A1 (en) * 2009-06-23 2010-12-24 Asten Assistance Services Traitements Environnement Nucleaire Device for drying sludge waste containing solvent obtained from treatment industry and cooling towers of nuclear plants, comprises evaporation unit, recovery unit, temperature increasing unit, injection unit, and drying enclosure
WO2011064450A1 (en) * 2009-11-24 2011-06-03 St1 Biofuels Oy Apparatus for recovery of organic compounds and drying of organic mass
WO2014171839A1 (en) 2013-04-19 2014-10-23 Trond Melhus Method and system for separation of oil and water from drilling mud
EP2986808A4 (en) * 2013-04-19 2017-01-25 Trond Melhus Method and system for separation of oil and water from drilling mud
CN103388962B (en) * 2013-08-15 2015-09-30 蚌埠玻璃工业设计研究院 A kind of drying device of fire proof material brick
CN103388962A (en) * 2013-08-15 2013-11-13 蚌埠玻璃工业设计研究院 Drying device of refractory material brick
CN103884159A (en) * 2014-03-19 2014-06-25 广东省昆虫研究所 Drying device for edible/medical/feed insects
CN104215041A (en) * 2014-09-02 2014-12-17 浙江朗博药业有限公司 Moisture absorption hot air circular drying oven
CN104729270A (en) * 2015-03-23 2015-06-24 覃健林 Drying tower air return system having waste heat recycling function
CN104729270B (en) * 2015-03-23 2017-04-05 覃健林 Drying tower air return system with heat recovery
EP3361198A1 (en) * 2017-02-13 2018-08-15 Danmarks Tekniske Universitet A slurry drying plant, a method for drying slurry and use of a slurry drying plant
WO2018146265A1 (en) * 2017-02-13 2018-08-16 Danmarks Tekniske Universitet A slurry drying plant, a method for drying slurry and use of a slurry drying plant
US11187458B2 (en) 2017-02-13 2021-11-30 Danmarks Tekniske Universitet Slurry drying plant, a method for drying slurry and use of a slurry drying plant
CN107917595A (en) * 2017-12-19 2018-04-17 赵立新 A kind of timber floor model decompression dry device
EP3800413A1 (en) 2019-10-03 2021-04-07 OSD System S.r.l. Sludge drying apparatus and process
CN113983765A (en) * 2021-10-11 2022-01-28 苏州西热节能环保技术有限公司 Lignite dewatering and upgrading system

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EP1800077A4 (en) 2013-05-22
FI20045322A0 (en) 2004-09-03
FI20045322A (en) 2006-03-04
CN201155907Y (en) 2008-11-26
RU67690U1 (en) 2007-10-27
EP1800077A1 (en) 2007-06-27

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