EP1434019A1 - Process for drying wet materials, in particular sludge, without the risk of explosion - Google Patents

Process for drying wet materials, in particular sludge, without the risk of explosion Download PDF

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Publication number
EP1434019A1
EP1434019A1 EP03300201A EP03300201A EP1434019A1 EP 1434019 A1 EP1434019 A1 EP 1434019A1 EP 03300201 A EP03300201 A EP 03300201A EP 03300201 A EP03300201 A EP 03300201A EP 1434019 A1 EP1434019 A1 EP 1434019A1
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EP
European Patent Office
Prior art keywords
gas
hopper
injection
drying
materials
Prior art date
Legal status (The legal status 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 status listed.)
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Application number
EP03300201A
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German (de)
French (fr)
Inventor
Philippe Blostein
Olivier Negro
Damien Burban
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by Air Liquide SA, LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Publication of EP1434019A1 publication Critical patent/EP1434019A1/en
Withdrawn legal-status Critical Current

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    • 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
    • F26B21/14—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects using gases or vapours other than air or steam, e.g. inert gases
    • 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 present invention relates to a method for drying sludge produced during the biological treatment of effluents such as urban or industrial wastewater with a view to of their purification.
  • Biological effluent treatment generally involves putting in contact these effluents with a biomass (micro-organisms) which degrades pollution contained in them by transforming organic molecules into minerals. Setting implementing such treatments leads to a gradual increase in the amount of biomass and the need to dispose of excess biomass commonly called "excess sludge”. To cope with the ever-increasing amount of this sludge biological solutions and their disposal, different solutions have been proposed. A solution is to extract this sludge and find a possible use for it. They can thus be used as fertilizer in agriculture (spreading).
  • the sludge withdrawn is generally dried and then put under form of granules before being stored.
  • the drying stage is generally carried out work by introducing still wet sludge (90% by weight of water) into means of transport, heating and mixing of sludge, for example a double worm screw placed in a heating jacket.
  • the dried sludge is introduced by means of a feed hopper into a shaping device such as a granulator.
  • the dried sludge and put in form are stored in storage silos.
  • the aim of the present invention is to propose a solution to limit these risks explosion in wet sludge drying processes, and more generally in the drying processes and shaping of any wet material including drying and shaping lead to the formation of dust generating risks ignition or explosion such as sludge.
  • It can for example be granules animal meal, granules or food powders (milk powder, ...), fertilizers, ...
  • It can also be chemicals, which following an operation spin, must be dried to be transformed into powder or granules.
  • the invention firstly relates to a process for drying materials wet in which an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide come into contact with wet materials during during drying.
  • the invention also relates to a device for drying wet materials.
  • a device for drying wet materials comprising means for heating wet materials and at least one means injection of gas into the means for heating wet materials.
  • FIG. 1 is a view diagram of a means for injecting the inerting gas usable in the process and the device according to the invention.
  • the invention relates firstly to a method of drying wet materials in which an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide comes into contact with wet materials during during the drying.
  • the dried wet materials after drying, can be shaped and the inerting gas can be brought into contact with the materials dried during their shaping.
  • the dried materials after drying or shaping, the dried materials are stored and the inerting gas is brought into contact with the materials dried during storage.
  • an inerting gas comprising nitrogen and / or CO 2 is introduced during drying and optionally during the shaping and / or storage of the dried materials.
  • the inerting gas used must have an oxygen concentration compatible with the treated wet materials and the risks of ignition or explosion linked to these materials. It is recommended to use an inerting gas with an oxygen concentration of less than 10% by volume.
  • the method uses an inerting gas comprising at least 90% by volume of nitrogen, or even at least 95%.
  • This type of inerting gas can be supplied from an "on-site" production unit, such as a membrane nitrogen production unit. It may for example be the FLOXAL® process marketed by Air Liquide.
  • a liquid nitrogen storage can be installed as a backup or for exceptional needs.
  • the inerting gas in concentration and flow such that an oxygen concentration is obtained in the drying atmosphere, and possibly in the shaping and storage atmospheres, less than or equal to 0 , 7 times the OMC, the OMC being the maximum oxygen concentration (called “Maximum Oxygen Content” in English) such that below, in all circumstances, ignition and explosion are avoided.
  • the JI varies according to each wet material and is generally determined by tests and measurements carried out in the laboratory.
  • the inerting gas flow rates are variable. During the implementation of the process, the inerting gas is generally introduced with a low flow, called “standby flow". This flow can for example be between 2 and 8 m 3 / h. According to the invention, the inerting gas is always introduced during drying.
  • stop flow rate a higher flow rate
  • curative flow an even greater flow, called “curative flow” can be injected in order to place the installation under maximum protection in the event of an ignition or explosion type incident.
  • This curative flow can for example be between 40 and 100 m 3 / h.
  • the introduction or stop of the introduction and the value of the gas flow are checked on the basis of measurements made at different points in the process ; these measures may in particular concern: stopping or running different process steps, oxygen concentration, temperature, pressure, humidity.
  • These checks can be carried out using at least one control, which collects the measurements and according to these, gives instructions for the introduction of the inerting gas and the flow and / or pressure of the inerting gas.
  • This process is applicable to drying and possibly to shaping and storage of sludge produced during the biological treatment of effluents.
  • the invention also relates to a device for drying wet materials.
  • a device for drying wet materials comprising means for heating wet materials and at least one means injection of gas into the means for heating wet materials.
  • the means for heating wet materials generally consist of a temperature-regulated cylinder inside which at least one worm is placed. This type of screw ensures the displacement and also the mixing of wet materials.
  • at least one means for injecting the inerting gas is present at the level of the means for heating wet materials.
  • the gas injection means can comprise at least one set of pipes mounted in series and / or in parallel, at least one of which portion of pipeline comprises gas injection orifices, said assembly being supplied by at least one gas supply pipe, each pipe being connected to the assembly at a primary connection node, the dimensioning of the assembly respecting the following relation: ⁇ i / ⁇ i ⁇ 1, preferably ⁇ 1.5, where ⁇ i represents the sum of the internal sections of the gas supply pipes which feed the assembly and ⁇ i represents the sum of the sections gas injection orifices in all of the pipes.
  • This type of injection means is more particularly described in patent EP-B1-0 659 515.
  • This injection means is generally placed on an opening made in the wall of the envelope of the means for heating wet materials.
  • the pipes of this gas injection means are protected by a grid. This grid makes it possible to prevent the deposit of suspended matter in the atmosphere on the pipes of the gas injection means.
  • the set of pipes of the gas injection means is fixed to the bottom of a trunk, the bottom of said trunk having at least one opening for the supply line of gas supplying all the pipes and said trunk having a mesh cover.
  • This box can then be fixed on an opening made in the envelope of the heating means for wet materials, the mesh cover being in contact with wet materials during drying.
  • This implementation is advantageous because the installation of the inerting gas injection means on the envelope of the means for heating wet materials is easy: it suffices to pierce the envelope with an opening corresponding to the size of the trunk, insert the trunk into this opening and connect a source of inerting gas to the opening made in the bottom of the trunk for the gas supply line supplying all the pipes.
  • the device comprises a hopper supply of dried materials cooperating with the heating means of the wet materials so as to supply a means for shaping the materials dried from the heating of wet materials using the hopper feed and at least one means for injecting gas into the feed hopper.
  • the feed hopper allows the introduction of dried materials from means of heating of wet materials in the shaping means. It's about usually a receptacle having shaped discharge sections funnel in which the dried matter flows by gravity. She can include means for regulating the flow of dried matter such as rotary or vibration agitators or a forcing screw.
  • the means of shaping dried materials can be a granulator or a pelletizer.
  • This gas injection means comprises at the level of the wall of the hopper at least a gas injection surface.
  • This injection surface can consist of a porous or injection orifices, preferably at least one orifice O.
  • This orifice O can be directly drilled in the wall of the hopper or drilled in a plate itself fixed on the wall of the hopper instead of an opening in the wall.
  • This latest implementation work may correspond to the case where the present invention is applied to a form already used and that must be adapted; thus, it is possible to replace a viewing window generally present on the wall of the hopper by a plate pierced with at least one orifice O and fixed to the wall of the hopper.
  • the gas injection means be set back from the passage of materials dried in the hopper and does not enter the internal volume of the hopper. So, he can be placed flush with the inner wall of the hopper. According to a particular mode, the injection ports O form a grid.
  • This injection surface is part of the means for injecting gas into the hopper, this injection means also comprising a gas supply line to this gas injection surface, or even these orifices O, and a homogenization chamber cooperating between the wall of the hopper and the wall of the supply line.
  • the homogenization chamber can be of any possible shape. Its volume is preferably fixed so that the speed of the gas in said chamber be less than the gas velocity at the injection surface and in the or O hole (s) drilled in the wall of the hopper. It must be waterproof so that pass gas from gas supply line to surface gas injection. For example, elastomer seals can be deposited on the edges of the homogenization chamber in contact with the wall of the hopper and on the edges of the homogenization chamber in contact with the wall of the pipe Power.
  • the section A of the homogenization chamber in contact with the wall of the hopper and possibly the sections a i of the gas injection orifices O drilled at the wall of the hopper verify the following relationship: the ratio A / ⁇ a i is greater than or equal to 1, preferably greater than or equal to 1.5, ⁇ a i representing the sum of the sections of the orifices O.
  • the gas injection orifices O drilled in the wall of the hopper all have the same section a.
  • the gas is brought into the homogenization chamber by the gas supply line which can have a cross section of varied shape such as round, square or rectangular.
  • One end of the pipe is connected to a source of the inerting gas. The other end is directed towards the orifice (s) O and is closed in its cross section.
  • the pipe has at least one radial opening o allowing the gas to be ejected perpendicularly to its direction of flow in the pipeline and towards the homogenization chamber. If more than one opening exists, these are usually located in the same cross section of the gas supply line.
  • the internal section S of the gas supply pipe and the sections s i of the openings o verify the following relationship: the ratio S / ⁇ s i is greater than or equal to 1, preferably greater than or equal to 1 , 5, ⁇ s i representing the sum of the sections s i of the openings o.
  • the radial opening (s) o of the gas supply line may all have the same section.
  • the gas supply pipe has four openings o placed in the same cross section of the pipe.
  • the invention also relates to the use of the above device for the treatment sludge produced during the biological treatment of effluents.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Treatment Of Sludge (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

The procedure, involving the use of a gas for drying a wet or damp material, has at least 90 per cent of the drying gas made up of an inert gas such as nitrogen or carbon dioxide. The gas is put into contact with the material being dried during its storage and drying processes, and is injected at a rate that gives an oxygen concentration in the atmospherenot above 0.7 times the maximum oxygen content (MOC). The drying procedure employs a heater with a series of channels mounted in series and/or in parallel and into which nitrogen or CO2 are injected. The injection system includes a neutralising gas feed (3) to an injection surface (2) on the wall of a hopper (1). One end (31) of the gas feed pipe is connected to the source of a neutralising gas, the other end (32) directed towards the injection surface is closed but has radial outlets (33) delivering the gas into a homogenisation chamber (4).

Description

La présente invention concerne un procédé de séchage de boues produites lors du traitement biologique d'effluents tels que les eaux usées urbaines ou industrielles en vue de leur épuration.The present invention relates to a method for drying sludge produced during the biological treatment of effluents such as urban or industrial wastewater with a view to of their purification.

Les traitements d'épuration biologiques d'effluents consistent généralement à mettre en contact ces effluents avec une biomasse (micro-organismes) qui dégrade la pollution contenue dans ceux-ci en transformant les molécules organiques en minéraux. La mise en oeuvre de tels traitements conduit à une augmentation progressive de la quantité de biomasse et à la nécessité d'évacuer la biomasse en excès communément appelée "boues en excès". Pour faire face à la quantité sans cesse croissante de ces boues biologiques en excès et de leur évacuation, différentes solutions ont été proposées. Une solution consiste à soutirer ces boues et à leur trouver une utilisation possible. Elles peuvent ainsi être utilisées comme engrais dans l'agriculture (épandage).Biological effluent treatment generally involves putting in contact these effluents with a biomass (micro-organisms) which degrades pollution contained in them by transforming organic molecules into minerals. Setting implementing such treatments leads to a gradual increase in the amount of biomass and the need to dispose of excess biomass commonly called "excess sludge". To cope with the ever-increasing amount of this sludge biological solutions and their disposal, different solutions have been proposed. A solution is to extract this sludge and find a possible use for it. They can thus be used as fertilizer in agriculture (spreading).

Dans ce cas, les boues soutirées sont généralement séchées puis mises sous forme de granulés avant d'être stockées. L'étape de séchage est généralement mise en oeuvre par introduction des boues encore humides (90 % en poids d'eau) dans des moyens de transport, de chauffage et de malaxage des boues, par exemple une double vis sans fin placée dans une enveloppe chauffante. A l'issue de cette étape de séchage, les boues séchées sont introduites au moyen d'une trémie d'alimentation dans un dispositif de mise en forme tel qu'un granulateur. Enfin, les boues séchées et mises en forme sont stockées dans des silos de stockage.In this case, the sludge withdrawn is generally dried and then put under form of granules before being stored. The drying stage is generally carried out work by introducing still wet sludge (90% by weight of water) into means of transport, heating and mixing of sludge, for example a double worm screw placed in a heating jacket. At the end of this drying step, the dried sludge is introduced by means of a feed hopper into a shaping device such as a granulator. Finally, the dried sludge and put in form are stored in storage silos.

Dans certaines conditions de mise en oeuvre de ce procédé de séchage et mise en forme des boues, des risques d'inflammation ou d'explosion peuvent apparaítre. Ainsi, au cours de l'étape de séchage, selon les utilisateurs, peu de risque d'inflammation existe au cours du fonctionnement normal de la double vis car l'atmosphère est très humide. Toutefois, lorsque le procédé de séchage est arrêté, l'auto-échauffement de la boue asséchée peut conduire à une explosion de gaz ou de poussières. Au cours de l'étape de mise en forme par un granulateur, c'est la présence de poussières, l'échauffement des parois et les frictions qui peuvent causer un risque d'explosion. Enfin, il est connu que lors du stockage en silo de produits poussiéreux, des explosions peuvent intervenir.Under certain conditions of implementation of this drying process and implementation form of sludge, risk of ignition or explosion may appear. So at during the drying stage, according to users, there is little risk of inflammation during normal operation of the twin screw because the atmosphere is very humid. However, when the drying process is stopped, the self-heating of the sludge drying can lead to an explosion of gas or dust. During the stage of shaped by a granulator, it is the presence of dust, the heating of walls and friction that can cause a risk of explosion. Finally, it is known that during from the storage of dusty products in silos, explosions can occur.

Le but de la présente invention est de proposer une solution pour limiter ces risques d'explosion dans les procédés de séchage des boues humides, et plus généralement dans les procédés de séchage et mise en forme de toute matière humide dont le séchage et la mise en forme conduisent à la formation de poussières générant des risques d'inflammation ou d'explosion telle que les boues. Il peut s'agir par exemple de granulés de farines animales, de granulés ou de poudres alimentaires (lait en poudre, ...), d'engrais, ... Il peut également s'agir de produits chimiques, qui suite à une opération d'essorage, doivent être séchés pour être transformés en poudre ou granulés.The aim of the present invention is to propose a solution to limit these risks explosion in wet sludge drying processes, and more generally in the drying processes and shaping of any wet material including drying and shaping lead to the formation of dust generating risks ignition or explosion such as sludge. It can for example be granules animal meal, granules or food powders (milk powder, ...), fertilizers, ... It can also be chemicals, which following an operation spin, must be dried to be transformed into powder or granules.

Dans ce but, l'invention concerne tout d'abord un procédé de séchage de matières humides dans lequel un gaz d'inertage comprenant au moins un gaz inerte choisi parmi l'azote et le dioxyde de carbone est mis au contact des matières humides au cours au cours du séchage.To this end, the invention firstly relates to a process for drying materials wet in which an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide come into contact with wet materials during during drying.

L'invention concerne également un dispositif de séchage de matières humides comprenant des moyens de chauffage des matières humides et au moins un moyen d'injection de gaz dans les moyens de chauffage des matières humides.The invention also relates to a device for drying wet materials. comprising means for heating wet materials and at least one means injection of gas into the means for heating wet materials.

D'autres caractéristiques et avantages de l'invention apparaítront à la lecture de la description qui va suivre. Des formes et des modes de réalisation de l'invention sont donnés à titre d'exemples non limitatifs, illustrés par la figure 1 qui est une vue schématique d'un moyen d'injection du gaz d'inertage utilisable dans le procédé et le dispositif selon l'invention.Other characteristics and advantages of the invention will appear on reading the description which follows. Forms and embodiments of the invention are given by way of nonlimiting examples, illustrated by FIG. 1 which is a view diagram of a means for injecting the inerting gas usable in the process and the device according to the invention.

L'invention concerne tout d'abord un procédé de séchage de matières humides dans lequel un gaz d'inertage comprenant au moins un gaz inerte choisi parmi l'azote et le dioxyde de carbone est mis au contact des matières humides au cours au cours du séchage.The invention relates firstly to a method of drying wet materials in which an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide comes into contact with wet materials during during the drying.

Selon une variante de l'invention, après le séchage, les matières humides séchées peuvent être mises en forme et le gaz d'inertage peut être mis au contact des matières séchées au cours de leur mise en forme.According to a variant of the invention, after drying, the dried wet materials can be shaped and the inerting gas can be brought into contact with the materials dried during their shaping.

Selon une autre variante de l'invention, après le séchage ou la mise en forme, les matières séchées sont stockées et le gaz d'inertage est mis au contact des matières séchées au cours du stockage.According to another variant of the invention, after drying or shaping, the dried materials are stored and the inerting gas is brought into contact with the materials dried during storage.

Ainsi, selon le procédé de l'invention, un gaz d'inertage comprenant de l'azote et/ou du CO2 est introduit au cours du séchage et éventuellement au cours de la mise en forme et/ou du stockage des matières séchées. De préférence, le gaz d'inertage utilisé doit avoir une concentration en oxygène compatible avec les matières humides traitées et les risques d'inflammation ou d'explosion liés à ces matières. Il est recommandé d'utiliser un gaz d'inertage à concentration en oxygène inférieure à 10 % en volume. Selon un mode préféré, le procédé met en oeuvre un gaz d'inertage comprenant au moins 90 % en volume d'azote, voire d'au moins 95 %. Ce type de gaz d'inertage peut être fourni à partir d'une unité de production «sur site», tel qu'une unité de production d'azote par membranes. Il peut s'agir par exemple du procédé FLOXAL® commercialisé par Air Liquide. Eventuellement, un stockage d'azote liquide peut être installé en secours ou pour les besoins exceptionnels. Thus, according to the method of the invention, an inerting gas comprising nitrogen and / or CO 2 is introduced during drying and optionally during the shaping and / or storage of the dried materials. Preferably, the inerting gas used must have an oxygen concentration compatible with the treated wet materials and the risks of ignition or explosion linked to these materials. It is recommended to use an inerting gas with an oxygen concentration of less than 10% by volume. According to a preferred embodiment, the method uses an inerting gas comprising at least 90% by volume of nitrogen, or even at least 95%. This type of inerting gas can be supplied from an "on-site" production unit, such as a membrane nitrogen production unit. It may for example be the FLOXAL® process marketed by Air Liquide. Optionally, a liquid nitrogen storage can be installed as a backup or for exceptional needs.

Il est recommandé d'injecter le gaz d'inertage en concentration et en débit tels que l'on obtienne une concentration en oxygène dans l'atmosphère de séchage, et éventuellement dans les atmosphères de mise en forme et stockage, inférieure ou égale à 0,7 fois la MOC, la MOC étant la concentration en oxygène maximale (dite "Maximum Oxygen Content" en anglais) telle qu'en deçà, en toutes circonstances, on évite inflammation et explosion. La MOC varie en fonction de chaque matière humide et est généralement déterminée par des essais et des mesures réalisées en laboratoire. Les débits du gaz d'inertage sont variables. Lors de la mise en oeuvre du procédé, le gaz d'inertage est généralement introduit avec un débit faible, dit « débit de veille ». Ce débit peut être par exemple compris entre 2 et 8 m3/h. Selon l'invention, le gaz d'inertage est toujours introduit au cours du séchage. En effet, du fait de l'injection du gaz au point le plus en amont procédé, le gaz est entraíné en aval et produit un effet d'inertage dans les éventuelles étapes suivantes du procédé (mise en forme puis stockage). Lors de l'arrêt du procédé, il est préférable d'introduire le gaz d'inertage avec un débit plus important, dit « débit d'arrêt ». Ce débit d'arrêt peut être par exemple compris entre 5 et 20 m3/h. Dans ce cas, il est recommandé d'injecter ce débit à toutes les étapes de séchage, mise en forme et stockage du procédé. Enfin, un débit encore plus important, dit « débit curatif » peut être injecté afin de placer l'installation sous protection maximale en cas d'incident du type inflammation ou explosion. Ce débit curatif peut être par exemple compris entre 40 et 100 m3/h.It is recommended to inject the inerting gas in concentration and flow such that an oxygen concentration is obtained in the drying atmosphere, and possibly in the shaping and storage atmospheres, less than or equal to 0 , 7 times the OMC, the OMC being the maximum oxygen concentration (called "Maximum Oxygen Content" in English) such that below, in all circumstances, ignition and explosion are avoided. The JI varies according to each wet material and is generally determined by tests and measurements carried out in the laboratory. The inerting gas flow rates are variable. During the implementation of the process, the inerting gas is generally introduced with a low flow, called "standby flow". This flow can for example be between 2 and 8 m 3 / h. According to the invention, the inerting gas is always introduced during drying. Indeed, due to the injection of gas at the most upstream point of the process, the gas is entrained downstream and produces an inerting effect in the possible subsequent steps of the process (shaping then storage). When stopping the process, it is preferable to introduce the inerting gas with a higher flow rate, called "stop flow rate". This stop flow can for example be between 5 and 20 m 3 / h. In this case, it is recommended to inject this flow rate at all stages of drying, shaping and storage of the process. Finally, an even greater flow, called "curative flow" can be injected in order to place the installation under maximum protection in the event of an ignition or explosion type incident. This curative flow can for example be between 40 and 100 m 3 / h.

Généralement, l'introduction ou l'arrêt de l'introduction et la valeur du débit du gaz d'inertage sont contrôlés en fonction de mesures réalisées en différents points du procédé ; ces mesures pouvant notamment concerner : l'arrêt ou la marche des différentes étapes du procédé, la concentration en oxygène, la température, la pression, l'hygrométrie. Ces contrôles peuvent être réalisés à l'aide d'au moins un dispositif de contrôle, qui recueille les mesures et en fonction de ces dernières, donne des consignes d'introduction du gaz d'inertage et de débit et/ou de pression du gaz d'inertage.Generally, the introduction or stop of the introduction and the value of the gas flow are checked on the basis of measurements made at different points in the process ; these measures may in particular concern: stopping or running different process steps, oxygen concentration, temperature, pressure, humidity. These checks can be carried out using at least one control, which collects the measurements and according to these, gives instructions for the introduction of the inerting gas and the flow and / or pressure of the inerting gas.

Ce procédé est applicable au séchage et éventuellement à la mise en forme et au stockage de boues produites lors du traitement biologique d'effluents.This process is applicable to drying and possibly to shaping and storage of sludge produced during the biological treatment of effluents.

L'invention concerne également un dispositif de séchage de matières humides comprenant des moyens de chauffage des matières humides et au moins un moyen d'injection de gaz dans les moyens de chauffage des matières humides.The invention also relates to a device for drying wet materials. comprising means for heating wet materials and at least one means injection of gas into the means for heating wet materials.

Les moyens de chauffage des matières humides sont généralement constitués d'un cylindre régulé en température à l'intérieur duquel est placée au moins une vis sans fin. Ce type de vis assure le déplacement et également le malaxage des matières humides. Ainsi, selon l'invention, au moins un moyen d'injection du gaz d'inertage est présent au niveau des moyens de chauffage des matières humides. Selon une mise en oeuvre préférée du dispositif selon l'invention, au niveau des moyens de chauffage des matières, le moyen d'injection de gaz peut comprendre au moins un ensemble de canalisation montées en série et/ou en parallèle, dont au moins une portion de canalisation comporte des orifices d'injection de gaz, ledit ensemble étant alimenté par au moins une conduite d'amenée de gaz, chaque conduite étant connectée à l'ensemble au niveau d'un noeud primaire de connexion, le dimensionnement de l'ensemble respectant la relation suivante : Σωi/Σϕi ≥ 1, de préférence ≥ 1,5, où Σωi représente la somme des sections internes des conduites d'amenée de gaz qui alimente l'ensemble et Σϕi représente la somme des sections des orifices d'injection de gaz de l'ensemble des canalisations. Ce type de moyen d'injection est plus particulièrement décrit dans le brevet EP-B1-0 659 515. Ce moyen d'injection est généralement placé sur une ouverture faite dans la paroi de l'enveloppe des moyens de chauffage des matières humides. De préférence, les canalisations de ce moyen d'injection de gaz sont protégées par une grille. Cette grille permet de prévenir le dépôt de matières en suspension dans l'atmosphère sur les canalisations du moyen d'injection de gaz. Selon une mise en oeuvre avantageuse de ce moyen d'injection, l'ensemble de canalisations du moyen d'injection de gaz est fixé au fond d'un coffre, le fond dudit coffre présentant au moins une ouverture pour la conduite d'amenée de gaz alimentant l'ensemble des canalisations et ledit coffre présentant un couvercle grillagé. Ce coffre peut alors être fixé sur une ouverture faite dans l'enveloppe des moyens de chauffage des matières humides, le couvercle grillagé étant au contact des matières humides en cours de séchage. Cette mise en oeuvre est intéressante car l'installation des moyens d'injection de gaz d'inertage sur l'enveloppe des moyens de chauffage des matières humides est facile : il suffit de percer l'enveloppe d'une ouverture correspondant à la taille du coffre, d'insérer le coffre dans cette ouverture et de connecter une source de gaz d'inertage sur l'ouverture faite dans le fond du coffre pour la conduite d'amenée de gaz alimentant l'ensemble des canalisations.The means for heating wet materials generally consist of a temperature-regulated cylinder inside which at least one worm is placed. This type of screw ensures the displacement and also the mixing of wet materials. Thus, according to the invention, at least one means for injecting the inerting gas is present at the level of the means for heating wet materials. According to a preferred implementation of the device according to the invention, at the level of the material heating means, the gas injection means can comprise at least one set of pipes mounted in series and / or in parallel, at least one of which portion of pipeline comprises gas injection orifices, said assembly being supplied by at least one gas supply pipe, each pipe being connected to the assembly at a primary connection node, the dimensioning of the assembly respecting the following relation: Σω i / Σϕ i ≥ 1, preferably ≥ 1.5, where Σω i represents the sum of the internal sections of the gas supply pipes which feed the assembly and Σϕ i represents the sum of the sections gas injection orifices in all of the pipes. This type of injection means is more particularly described in patent EP-B1-0 659 515. This injection means is generally placed on an opening made in the wall of the envelope of the means for heating wet materials. Preferably, the pipes of this gas injection means are protected by a grid. This grid makes it possible to prevent the deposit of suspended matter in the atmosphere on the pipes of the gas injection means. According to an advantageous implementation of this injection means, the set of pipes of the gas injection means is fixed to the bottom of a trunk, the bottom of said trunk having at least one opening for the supply line of gas supplying all the pipes and said trunk having a mesh cover. This box can then be fixed on an opening made in the envelope of the heating means for wet materials, the mesh cover being in contact with wet materials during drying. This implementation is advantageous because the installation of the inerting gas injection means on the envelope of the means for heating wet materials is easy: it suffices to pierce the envelope with an opening corresponding to the size of the trunk, insert the trunk into this opening and connect a source of inerting gas to the opening made in the bottom of the trunk for the gas supply line supplying all the pipes.

Selon une variante du dispositif selon l'invention, le dispositif comprend une trémie d'alimentation en matières séchées coopérant avec les moyens de chauffage des matières humides de manière à alimenter un moyen de mise en forme des matières séchées issues des moyens de chauffage des matières humides à l'aide de la trémie d'alimentation et au moins un moyen d'injection de gaz dans la trémie d'alimentation. La trémie d'alimentation permet d'introduire les matières séchées provenant de moyens de chauffage des matières humides dans les moyens de mise en forme. Il s'agit habituellement d'un réceptacle présentant des sections de déchargement en forme d'entonnoir dans laquelle les matières séchées s'écoulent par gravité. Elle peut comprendre des moyens pour réguler l'écoulement des matières séchées tels que des agitateurs rotatifs ou à vibrations ou une vis de forçage. Les moyens de mise en forme des matières séchées peuvent être un granulateur ou un pelletiseur.According to a variant of the device according to the invention, the device comprises a hopper supply of dried materials cooperating with the heating means of the wet materials so as to supply a means for shaping the materials dried from the heating of wet materials using the hopper feed and at least one means for injecting gas into the feed hopper. The feed hopper allows the introduction of dried materials from means of heating of wet materials in the shaping means. It's about usually a receptacle having shaped discharge sections funnel in which the dried matter flows by gravity. She can include means for regulating the flow of dried matter such as rotary or vibration agitators or a forcing screw. The means of shaping dried materials can be a granulator or a pelletizer.

Selon une mise en oeuvre préférée de cette variante du dispositif selon l'invention, illustrée par la figure 1, au niveau de la trémie d'alimentation, le moyen d'injection de gaz dans la trémie d'alimentation en matières séchées comprend :

  • au moins une surface (2) d'injection de gaz au niveau de la paroi de la trémie (1),
  • une conduite d'alimentation en gaz (3) de la trémie par cette surface d'injection de gaz :
    • dont une extrémité (31) est reliée à une source de gaz d'inertage,
    • dont l'autre extrémité (32), qui est dirigée vers la surface d'injection, est fermée,
    • et qui présente au moins une ouverture o (33) radiale permettant une éjection du gaz perpendiculairement à son sens de circulation dans la conduite, et
  • une chambre d'homogénéisation (4) coopérant entre la paroi de la trémie et la conduite d'alimentation en gaz (3) de manière à ce que le gaz éjecté des ouvertures o (33) pénètre dans la trémie par la surface d'injection.
According to a preferred implementation of this variant of the device according to the invention, illustrated by FIG. 1, at the level of the feed hopper, the means for injecting gas into the dry matter feed hopper comprises:
  • at least one gas injection surface (2) at the wall of the hopper (1),
  • a gas supply pipe (3) to the hopper via this gas injection surface:
    • one end of which (31) is connected to a source of inerting gas,
    • the other end (32) of which is directed towards the injection surface, is closed,
    • and which has at least one radial opening o (33) allowing ejection of the gas perpendicular to its direction of circulation in the pipe, and
  • a homogenization chamber (4) cooperating between the wall of the hopper and the gas supply pipe (3) so that the gas ejected from the openings o (33) enters the hopper through the injection surface .

Ce moyen d'injection de gaz comprend au niveau de la paroi de la trémie au moins une surface d'injection de gaz. Cette surface d'injection peut être constituée d'un poreux ou d'orifices d'injection, de préférence au moins un orifice O. Cet orifice O peut être directement percé dans la paroi de la trémie ou percé dans une plaque elle-même fixée sur la paroi de la trémie à la place d'une ouverture dans la paroi. Cette dernière mise en oeuvre peut correspondre au cas où la présente invention est appliquée à un dispositif de mise en forme déjà exploité et que l'on doit adapter ; ainsi, il est possible de remplacer un hublot de visualisation généralement présent sur la paroi de la trémie par une plaque percée d'au moins un orifice O et fixée sur la paroi de la trémie. Il est également préférable que le moyen d'injection de gaz soit situé en retrait du passage des matières séchées dans la trémie et ne pénètre pas dans le volume interne de la trémie. Ainsi, il peut être placé au ras de la paroi interne de la trémie. Selon un mode particulier, les orifices d'injection O forment un grillage.This gas injection means comprises at the level of the wall of the hopper at least a gas injection surface. This injection surface can consist of a porous or injection orifices, preferably at least one orifice O. This orifice O can be directly drilled in the wall of the hopper or drilled in a plate itself fixed on the wall of the hopper instead of an opening in the wall. This latest implementation work may correspond to the case where the present invention is applied to a form already used and that must be adapted; thus, it is possible to replace a viewing window generally present on the wall of the hopper by a plate pierced with at least one orifice O and fixed to the wall of the hopper. he is also preferable that the gas injection means be set back from the passage of materials dried in the hopper and does not enter the internal volume of the hopper. So, he can be placed flush with the inner wall of the hopper. According to a particular mode, the injection ports O form a grid.

Cette surface d'injection, éventuellement constituée des orifices O, fait partie du moyen d'injection de gaz dans la trémie, ce moyen d'injection comprenant également une conduite d'alimentation en gaz vers cette surface d'injection de gaz, voire ces orifices O, et une chambre d'homogénéisation coopérant entre la paroi de la trémie et la paroi de la conduite d'alimentation. La chambre d'homogénéisation peut être de toute forme possible. Son volume est de préférence fixé de manière à ce que la vitesse du gaz dans ladite chambre soit inférieure à la vitesse du gaz au niveau de la surface d'injection et dans le ou les orifice(s) O percé(s) dans la paroi de la trémie. Elle doit être étanche de manière à assurer le passage du gaz depuis la conduite d'alimentation en gaz vers la surface d'injection de gaz. Par exemple, des joints d'élastomère peuvent être déposés sur les bords de la chambre d'homogénéisation en contact avec la paroi de la trémie et sur les bords de la chambre d'homogénéisation en contact avec la paroi de la conduite d'alimentation.This injection surface, possibly made up of orifices O, is part of the means for injecting gas into the hopper, this injection means also comprising a gas supply line to this gas injection surface, or even these orifices O, and a homogenization chamber cooperating between the wall of the hopper and the wall of the supply line. The homogenization chamber can be of any possible shape. Its volume is preferably fixed so that the speed of the gas in said chamber be less than the gas velocity at the injection surface and in the or O hole (s) drilled in the wall of the hopper. It must be waterproof so that pass gas from gas supply line to surface gas injection. For example, elastomer seals can be deposited on the edges of the homogenization chamber in contact with the wall of the hopper and on the edges of the homogenization chamber in contact with the wall of the pipe Power.

Selon le mode préféré, la section A de la chambre d'homogénéisation au contact avec la paroi de la trémie et éventuellement les sections ai des orifices O d'injection de gaz percés au niveau de la paroi de la trémie vérifient la relation suivante : le rapport A/Σai est supérieur ou égal à 1, de préférence supérieur ou égal à 1,5, Σai représentant la somme des sections des orifices O. De manière pratique, les orifices O d'injection de gaz percés dans la paroi de la trémie présentent tous la même section a.According to the preferred embodiment, the section A of the homogenization chamber in contact with the wall of the hopper and possibly the sections a i of the gas injection orifices O drilled at the wall of the hopper verify the following relationship: the ratio A / Σa i is greater than or equal to 1, preferably greater than or equal to 1.5, Σa i representing the sum of the sections of the orifices O. In practical terms, the gas injection orifices O drilled in the wall of the hopper all have the same section a.

Le gaz est amené dans la chambre d'homogénéisation par la conduite d'alimentation en gaz qui peut présenter une section de forme variée telle que ronde, carrée ou rectangulaire. Une extrémité de la conduite est reliée à une source du gaz d'inertage. L'autre extrémité est dirigée vers le ou les orifices O et est fermée dans sa section droite. La conduite présente au moins une ouverture o radiale permettant une éjection du gaz perpendiculairement à son sens de circulation dans la canalisation et vers la chambre d'homogénéisation. Si plusieurs ouvertures o existent, ces dernières sont habituellement situées dans la même section droite de la conduite d'alimentation en gaz. Selon le mode préféré, la section interne S de la conduite d'alimentation en gaz et les sections si des ouvertures o vérifient la relation suivante : le rapport S/Σsi est supérieur ou égal à 1, de préférence supérieur ou égal à 1,5, Σsi représentant la somme des sections si des ouvertures o. La ou les ouverture(s) o radiales de la conduite d'alimentation en gaz peuvent toutes présenter la même section s. Selon un mode particulier, la conduite d'alimentation en gaz présente quatre ouvertures o placées dans la même section droite de la conduite.The gas is brought into the homogenization chamber by the gas supply line which can have a cross section of varied shape such as round, square or rectangular. One end of the pipe is connected to a source of the inerting gas. The other end is directed towards the orifice (s) O and is closed in its cross section. The pipe has at least one radial opening o allowing the gas to be ejected perpendicularly to its direction of flow in the pipeline and towards the homogenization chamber. If more than one opening exists, these are usually located in the same cross section of the gas supply line. According to the preferred mode, the internal section S of the gas supply pipe and the sections s i of the openings o verify the following relationship: the ratio S / Σs i is greater than or equal to 1, preferably greater than or equal to 1 , 5, Σs i representing the sum of the sections s i of the openings o. The radial opening (s) o of the gas supply line may all have the same section. According to a particular embodiment, the gas supply pipe has four openings o placed in the same cross section of the pipe.

L'invention concerne également l'utilisation du dispositif précédent pour le traitement de boues produites lors du traitement biologique d'effluents.The invention also relates to the use of the above device for the treatment sludge produced during the biological treatment of effluents.

La figure 1 illustre le moyen d'injection du gaz d'inertage sur la trémie d'alimentation. Ce moyen d'injection de gaz est disposé sur la paroi de la trémie (1). Il comprend :

  • 3 orifices circulaires d'injection de gaz O (2), de diamètre 0,55 cm, percés dans une plaque (5) vissée sur la paroi de la trémie à la place d'un hublot de visualisation.
  • une conduite d'alimentation en gaz (3) vers ces orifices d'injection de gaz O (2). Il s'agit d'une canalisation de section circulaire et de diamètre 1,5 cm. Son extrémité (31) est reliée à une source de gaz. Son autre extrémité (32) est bouchée. Dans sa portion proche de l'extrémité bouchée (32), la conduite comporte quatre ouvertures circulaires o (33) toutes du même diamètre (0,5 cm) placés dans la même section droite de la canalisation et équidistants les uns des autres. Le rapport S/Σsi est de 2,25.
  • une chambre d'homogénéisation (4) dont la section est de forme circulaire et dont le diamètre intérieur est de 3,6 cm. Un joint silicone assure l'étanchéité de la chambre avec la paroi de la trémie. Le rapport A/Σai est de 14,3.
FIG. 1 illustrates the means for injecting the inerting gas onto the feed hopper. This gas injection means is arranged on the wall of the hopper (1). He understands :
  • 3 circular O gas injection holes (2), 0.55 cm in diameter, drilled in a plate (5) screwed onto the wall of the hopper instead of a viewing window.
  • a gas supply line (3) to these gas injection ports O (2). It is a pipe of circular section and diameter 1.5 cm. Its end (31) is connected to a gas source. Its other end (32) is blocked. In its portion close to the blocked end (32), the pipe has four circular openings o (33) all of the same diameter (0.5 cm) placed in the same cross section of the pipe and equidistant from each other. The ratio S / Σs i is 2.25.
  • a homogenization chamber (4) whose section is circular and whose internal diameter is 3.6 cm. A silicone seal seals the chamber with the wall of the hopper. The ratio A / Σa i is 14.3.

Claims (16)

Procédé de séchage de matières humides dans lequel un gaz d'inertage comprenant au moins un gaz inerte choisi parmi l'azote et le dioxyde de carbone est mis au contact des matières humides au cours du séchage.A method of drying wet materials in which an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide is brought into contact wet materials during drying. Procédé selon la revendication 1, caractérisé en ce que le gaz d'inertage comprend au moins 90 % en volume d'au moins un gaz inerte.Method according to claim 1, characterized in that the inerting gas comprises at least 90% by volume of at least one inert gas. Procédé selon la revendication 1 ou 2, caractérisé en ce qu'après le séchage, les matières humides séchées sont mises en forme et le gaz d'inertage est mis au contact des matières séchées au cours de leur mise en forme.Method according to claim 1 or 2, characterized in that after drying, the dried moist materials are shaped and the inerting gas is brought into contact with the dried materials during their shaping. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'après le séchage ou la mise en forme, les matières humides séchées sont stockées et en ce qu'un gaz d'inertage comprenant au moins un gaz inerte choisi parmi l'azote et le dioxyde de carbone est mis au contact des matières humides au cours du stockage.Method according to one of the preceding claims, characterized in that after drying or shaping, the dried wet materials are stored and in that an inerting gas comprising at least one inert gas chosen from nitrogen and carbon dioxide is brought into contact with wet materials during storage. Procédé selon l'une des revendications précédentes, caractérisé en ce que les matières humides sont des boues produites lors du traitement biologique d'effluents.Method according to one of the preceding claims, characterized in that the wet materials are sludges produced during the biological treatment of effluents. Procédé selon l'une des revendications précédentes, caractérisé en ce que le gaz d'inertage est injecté en concentration et en débit tels que la concentration en oxygène dans l'atmosphère soit inférieure ou égale à 0,7 fois la MOC.Method according to one of the preceding claims, characterized in that the inerting gas is injected in a concentration and in a flow rate such that the oxygen concentration in the atmosphere is less than or equal to 0.7 times the MOC. Dispositif de séchage de matières humides comprenant des moyens de chauffage des matières humides, caractérisé en ce qu'il comprend au moins un moyen d'injection de gaz dans les moyens de chauffage des matières séchées.Device for drying wet materials comprising means for heating wet materials, characterized in that it comprises at least one means for injecting gas into the means for heating the dried materials. Dispositif selon la revendication 7, caractérisé en ce que le moyen d'injection de gaz dans les moyens de chauffage des matières comprend au moins un ensemble de canalisations montées en série et/ou en parallèle, dont au moins une portion de canalisation comporte des orifices d'injection de gaz, ledit ensemble étant alimenté par au moins une conduite d'amenée de gaz, chaque conduite étant connectée à l'ensemble au niveau d'un noeud primaire de connexion, le dimensionnement de l'ensemble respectant la relation suivante : Σωi/Σϕi ≥ 1, de préférence ≥ 1,5, où Σωi représente la somme des sections internes des conduites d'amenée de gaz qui alimente l'ensemble et Σϕi représente la somme des sections des orifices d'injection de gaz de l'ensemble des canalisations.Device according to Claim 7, characterized in that the means for injecting gas into the material heating means comprises at least one set of pipes mounted in series and / or in parallel, at least one portion of the pipe having orifices gas injection, said assembly being supplied by at least one gas supply pipe, each pipe being connected to the assembly at a primary connection node, the dimensioning of the assembly respecting the following relationship: Σω i / Σϕ i ≥ 1, preferably ≥ 1.5, where Σω i represents the sum of the internal sections of the gas supply pipes which supply the assembly and Σϕ i represents the sum of the sections of the injection orifices of gas from all pipelines. Dispositif selon la revendication 7 ou 8, caractérisé en ce que le moyen d'injection de gaz dans les moyens de chauffage des matières humides est protégé par une grille.Device according to claim 7 or 8, characterized in that the means for injecting gas into the means for heating wet materials is protected by a grid. Dispositif selon la revendication 9, caractérisé en ce que l'ensemble de canalisations du moyen d'injection de gaz dans les moyens de chauffage sont fixées au fond d'un coffre, le fond dudit coffre présentant au moins une ouverture pour la conduite d'amenée de gaz alimentant l'ensemble des canalisations et ledit coffre présentant un couvercle grillagé.Device according to claim 9, characterized in that the set of pipes of the gas injection means in the heating means are fixed to the bottom of a trunk, the bottom of said trunk having at least one opening for the supply line. gas supply supplying all the pipes and said trunk having a mesh cover. Dispositif selon l'une des revendications 7 à 10, caractérisé en ce qu'il comprend une trémie d'alimentation en matières séchées coopérant avec les moyens de chauffage des matières humides de manière à alimenter un moyen de mise en forme des matières séchées issues des moyens de chauffage des matières humides à l'aide de la trémie d'alimentation et au moins un moyen d'injection de gaz dans la trémie d'alimentation.Device according to one of Claims 7 to 10, characterized in that it comprises a hopper for supplying dried materials cooperating with the means for heating the wet materials so as to supply a means for shaping the dried materials from the means for heating wet materials using the feed hopper and at least one means for injecting gas into the feed hopper. Dispositif selon la revendication 11, caractérisé en ce que le moyen d'injection de gaz dans la trémie d'alimentation en matières séchées comprend : au moins une surface (2) d'injection de gaz au niveau de la paroi de la trémie (1), une conduite d'alimentation en gaz (3) de la trémie par cette surface d'injection de gaz : dont une extrémité (31) est reliée à une source de gaz d'inertage, dont l'autre extrémité (32), qui est dirigée vers la surface d'injection, est fermée, et qui présente au moins une ouverture o (33) radiale permettant une éjection du gaz perpendiculairement à son sens de circulation dans la conduite, et une chambre d'homogénéisation (4) coopérant entre la paroi de la trémie et la conduite d'alimentation en gaz (3) de manière à ce que le gaz éjecté des ouvertures o (33) pénètre dans la trémie par la surface d'injection. Device according to claim 11, characterized in that the means for injecting gas into the dried material supply hopper comprises: at least one gas injection surface (2) at the wall of the hopper (1), a gas supply pipe (3) to the hopper via this gas injection surface: one end of which (31) is connected to a source of inerting gas, the other end (32) of which is directed towards the injection surface, is closed, and which has at least one radial opening o (33) allowing ejection of the gas perpendicular to its direction of circulation in the pipe, and a homogenization chamber (4) cooperating between the wall of the hopper and the gas supply pipe (3) so that the gas ejected from the openings o (33) enters the hopper through the injection surface . Dispositif selon la revendication 12, caractérisé en ce que la surface d'injection de gaz (2) au niveau de la paroi de la trémie (1) est constituée d'au moins un orifice O (2). Device according to claim 12, characterized in that the gas injection surface (2) at the wall of the hopper (1) consists of at least one orifice O (2). Dispositif selon la revendication 13, caractérisé en ce que les orifices d'injection O forment un grillage.Device according to claim 13, characterized in that the injection orifices O form a grid. Moyen d'injection de gaz adaptable sur tout type de dispositif nécessitant l'injection d'un gaz, caractérisé en ce que le moyen d'injection est constitué d'un coffre : dans le fond duquel est fixé au moins un ensemble de canalisations montées en série et/ou en parallèle, dont au moins une portion de canalisation comporte des orifices d'injection de gaz, ledit ensemble étant alimenté par au moins une conduite d'amenée de gaz, chaque conduite étant connectée à l'ensemble au niveau d'un noeud primaire de connexion, le dimensionnement de l'ensemble respectant la relation suivante : Σωi / Σϕi ≥ 1, de préférence ≥ 1,5, où Σωi représente la somme des sections internes des conduites d'amenée de gaz qui alimente l'ensemble et Σϕi représente la somme des sections des orifices d'injection de gaz de l'ensemble des canalisations, et le fond dudit coffre présentant au moins une ouverture pour la conduite d'amenée de gaz alimentant l'ensemble des canalisations, et ledit coffre présentant un couvercle grillagé. Gas injection means adaptable to any type of device requiring the injection of a gas, characterized in that the injection means consists of a box: in the bottom of which is fixed at least one set of pipes mounted in series and / or in parallel, at least one portion of which includes gas injection orifices, said set being supplied by at least one supply line of gas, each pipe being connected to the assembly at a primary connection node, the dimensioning of the assembly respecting the following relationship: Σω i / Σϕ i ≥ 1, preferably ≥ 1.5, where Σω i represents the sum of the internal sections of the gas supply pipes which supply the assembly and Σϕ i represents the sum of the sections of the gas injection orifices of all the pipes, and the bottom of said box having at least one opening for the gas supply pipe supplying all the pipes, and said chest having a mesh cover. Utilisation du dispositif selon l'une des revendications 7 à 14 pour le traitement de boues produites lors du traitement biologique d'effluents.Use of the device according to one of claims 7 to 14 for the treatment of sludge produced during the biological treatment of effluents.
EP03300201A 2002-11-08 2003-11-06 Process for drying wet materials, in particular sludge, without the risk of explosion Withdrawn EP1434019A1 (en)

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FR0214036A FR2847030B1 (en) 2002-11-08 2002-11-08 PROCESS FOR DRYING WET MATERIALS, IN PARTICULAR SLUDGE, WITHOUT RISK OF EXPLOSION
FR0214036 2002-11-08

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ITMI20061846A1 (en) 2006-09-27 2008-03-28 Geoline Srl SYSTEM FOR THE SAFETY OF DRYING SYSTEMS OF ORGANIC SUBSTANCES SUFFICIENT TO CAUSE EPLOSIVE REACTIONS AND PROCEDURE FOR DRYING THESE SUBSTANCES

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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FR1471706A (en) * 1965-03-19 1967-03-03 Ass Octel Lead-bearing sludge treatment process
US3597833A (en) * 1969-09-03 1971-08-10 Gen Electric Method of performing a brazing operation on terminal structure of metal braid
US4092784A (en) * 1975-07-08 1978-06-06 Basf Aktiengesellschaft Process and apparatus for drying and heating nylon granules
EP0333329A2 (en) * 1988-02-26 1989-09-20 Permian Research Corporation Drying method and apparatus
EP0491247A1 (en) * 1990-12-18 1992-06-24 Thyssen Still Otto Anlagentechnik GmbH Process for explosion-proof drying of sewage sludge
EP0569999A1 (en) * 1992-05-15 1993-11-18 Mitsui Petrochemical Industries, Ltd. Drying hopper and powder drying method using the same
EP0659515A1 (en) * 1993-12-22 1995-06-28 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Gas injection device and process for forming a controlled atmosphere in a confined space
US5561915A (en) * 1995-07-12 1996-10-08 Vandergriff; Johnie B. Storage container with sealed storage compartment for a purging gas cartridge
US6378753B1 (en) * 1997-11-07 2002-04-30 Messer Griesheim Gmbh Gas distribution system which can be connected to a gas supply
WO2002024585A1 (en) * 2000-09-25 2002-03-28 Seghers Better Technology Group Method and apparatus for sludge drying and simultaneous pelletization
DE10049263A1 (en) * 2000-09-28 2002-04-11 Buehler Ag Apparatus for thermal treatment of granular polymers comprises hopper whose walls have sieve sections with smooth, structured surface, allowing nitrogen-containing gas to be fed through granules, and smooth sections with structured surface

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FR2847030A1 (en) 2004-05-14
FR2847030B1 (en) 2005-12-02

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