DE102020000818A1 - Utilization of digested sewage sludge in a fluidized bed plant - Google Patents

Abstract

According to the invention, sewage sludge is solar-thermally dried and, by mixing, brought to a calorific value / calorific value at which automatic combustion in a fluidized bed furnace / furnace is ensured.

Description

The invention relates to the utilization of completely or partially digested sewage sludge by incineration in a furnace, preferably in a fluidized bed furnace. Sewage sludge is usually dewatered before incineration in order to increase its calorific value. The first step is mechanical dewatering, for example by filtering or using a centrifuge. Filtering in a filter press is particularly effective. During the filtering process, liquid is removed from the sewage sludge. A DR content of between 25 and 30% by weight (proportion of dry matter in the sewage sludge) can be generated.

The higher the TR content of the sewage sludge, the easier the sewage sludge burns. The calorific value / calorific value of the sewage sludge also depends on the proportion of its combustible components. Depending on the origin of the sewage sludge from municipal drainage or from industrial drainage, the sewage sludge has a different calorific value / calorific value.

Below a certain calorific value / calorific value, a supporting fire is required to burn the sewage sludge. Above the specific calorific value / calorific value, the sewage sludge burns without a supporting fire. This is called self-combustion. The specific calorific value / calorific value depends on the type of furnace and the properties of the furnace in detail. For example, sewage sludge from the Emsch sewage works in Bottrop with a dry matter content of 52% by weight has a sufficient calorific value for automatic combustion in a fluidized bed furnace of the sewage treatment plant. In the case of other sewage sludge and / or other firing, a corresponding calorific value can be present with a higher or lower DR content.

It is known to increase the calorific value / calorific value of sewage sludge by adding coal. By adding coal, the sludge can also be dewatered to a greater extent (for example to 35 to 40% by weight).

An older proposal set itself the task of bringing the sewage sludge without coal to a degree of dryness at which independent combustion in a fluidized bed furnace is possible.

• -für die Lagerung mit üblichen Vorrichtungen handhabbar ist
• -für den Transport mit üblichen Vorrichtungen handhabbar ist
• -mit üblichen Beschickungseinrichtungen in die Wirbelschichtfeuerung aufgegeben werden kann.

In addition, the sewage sludge must be such that it

• - Can be handled for storage with conventional devices
• - Can be handled with conventional devices for transport
• -can be fed into the fluidized bed furnace with conventional charging devices.

The problem is solved with the features of the main claim. The subclaims describe preferred embodiments.

The devices for drying and transporting the sewage sludge depend on the type and extent of drying and transport. The fluidized bed furnace / furnace includes charging devices, in particular throwing feeders. In addition, the furnace atmosphere must be separated from the ambient atmosphere when loading sewage sludge. For this purpose, the throw feeder is arranged on the furnace and the sewage sludge is fed to the throw feeder, for example via a screw conveyor.

The sewage sludge (apart from exceptional cases) should not be in the glue phase for drying, transport and charging. The glue phase describes the stickiness of the sewage sludge under mechanical stress. Tackiness begins at a DR content of around 40% and ends at a DR content of around 60%. Depending on the nature of the sewage sludge, there are different limits for the glue phase. The stickiness leads to a lump or solidification of the sewage sludge under mechanical stress. The clumping and solidification can block feeders and conveyors. The lumps and solidifications are particularly problematic in closed housings, especially in silos / storage tanks / containers / housings of screw conveyors. Feed material is collected in silos so that it can be withdrawn when required. Templates are also containers in which feed material is collected so that it can be withdrawn when necessary. When sewage sludge is incinerated, the sewage sludge is the input material.

Even when sewage sludge is transported on conveyor belts, lumps and thickening can occur if the sewage sludge falls from one belt onto another belt downstream in the conveying direction. The series connection of several conveyor belts or the subsequent connection of a conveyor belt cannot be avoided in many cases. This is especially true for kinking conveyor routes. In these cases, the rear end of the first conveyor belt in the conveying direction protrudes over the front end of the second conveyor belt in the conveying direction and falls Sewage sludge from one end of the conveyor belt to the other end of the conveyor belt.

In order to precisely determine the glue phase, test specimens of the sewage sludge concerned can be taken and mechanically stressed. As a mechanical load, the sewage sludge specimens can be pressed together between two plates / jaws, for example. In the case of sewage sludge with a dry matter content below the glue phase, the sewage sludge easily flows out between the plates / jaws under pressure. In the case of sewage sludge with a dry matter content above the glue phase, the sewage sludge breaks apart in a crumbly manner after the plates / jaws have been loosened. In the glue phase, a solid body is created between the plates / jaws.

There are several ways to counteract stickiness.

Most of the proposals are based on the addition of an additive, for example a dry substance.

• DE 19531379 , DE19501736 , DE19512563 , EP883778 , EP526458 , EP3178577 , DE9208456 , DE4215530 , DE4138036 , EP2788701 , DE2401552 , EP1287304 , EP716264 , EP591299 , EP542958 , EP526458 , EP588152 .

These include the following suggestions:

• DE 19531379 , DE19501736 , DE19512563 , EP883778 , EP526458 , EP3178577 , DE9208456 , DE4215530 , DE4138036 , EP2788701 , DE2401552 , EP1287304 , EP716264 , EP591299 , EP542958 , EP526458 , EP588152 .

Other solutions provide for drying the dewatered sewage sludge beyond the glue phase.

The older proposal also starts with drying. For this purpose, the older proposal turns to a drying process that does not seem suitable without further ado. This is solar drying. Solar drying is based on solar radiation. At the same time, a roof that is permeable to the sun's rays (glass roof or roof with transparent plastic) ensures that the drying is not canceled by rain.
For solar drying, enclosures with glass or transparent plastic that allow the sun's rays to pass through are particularly suitable. This also includes greenhouses, for example. Greenhouses can offer all the desired functions and have significant cost advantages over other transparent roofs.
In greenhouses, the sewage sludge can be spread out easily, turned repeatedly to dry it well, and after drying it can be picked up again and transported away. The sewage sludge is preferably spread as evenly as possible on the ground in order to create uniform conditions with regard to the thickness of the sewage sludge layer spread out for drying.

Greenhouses can be heated and ventilated.
The aim of the heating is to maintain a desired drying process at least when the solar radiation decreases, or to adapt the drying process to a desired course.
By venting, moist vapors (gases / vapors arising from drying) can be removed and exchanged for air / ambient air.
Preferably, the evacuated vapors are at least partially freed from the odorous substances contained therein. Various measures are suitable for removing odors, for example the use of biofilters, activated carbon filters or the air removed by combustion.
It is beneficial if the vapors removed can be fed to the fluidized bed furnace / furnace as combustion air.

If facilities other than greenhouses are provided, it is also advantageous to combine these facilities with heating and ventilation.

Preferably, at least one heating is provided for the sewage sludge drying, in order to step in with the heating, especially in the case of insufficient solar drying, or to be able to design the course of the drying independently of the respective solar radiation. Floor heating is an advantage. In the case of floor heating, heating pipes are preferably laid in the floor on which the sewage sludge to be dried is spread. Due to the small distance between the heating pipes and the contact surface with sewage sludge, there is an advantageous heat transfer to the sewage sludge. An extremely advantageous heat transfer is given if the heating pipes also form the contact surface with the sewage sludge or if the floor is formed by a metal surface and the heating pipes are in contact with the metal surface forming the floor. The better the heat transfer, the better the heat content of the heating medium can be used.

The combination of solar drying and heating is referred to below as solar thermal drying.

Heating with condensate heat or exhaust gas / flue gas or heat from a block-type thermal power station is optionally provided as additional heating.

The condensate heat can come from a steam turbine. The steam turbine is operated with the steam that is produced with the
Fluidized bed combustion / furnace is generated. The fluidized bed furnace / furnace is available in different embodiments, for example as a stationary fluidized bed or as a circulating fluidized bed.
In the stationary fluidized bed, the fuel is kept in suspension in the combustion chamber by means of the combustion air introduced from below. The fuel particles move in the air flow until they are burned. The particles remaining after combustion are carried out of the furnace with the flue gases. The flue gases pass through a filter, possibly also a desulfurization station and / or a denitrification station.

The circulating fluidized bed differs from the stationary fluidized bed in that it has a circulating stream of combustion gases in which the fuel particles are located, instead of a fluidized bed.

The stationary fluidized bed combustion as well as the circulating fluidized bed combustion have a steam boiler through which water flows. The steam boiler is designed as a fin wall boiler or tube bundle boiler. The heating of the cooling water produces steam, which preferably drives a turbine to generate electricity at the appropriate pressure. The electricity generated is used internally in the Bottrop Emscher sewage treatment plant. When the steam fed into the turbine has passed its energy on to the turbine, the steam has lost its pressure. When the steam is released, a condensate is produced which is usually fed back into the water circuit for renewed steam recovery. Due to the design of the steam turbine, the condensate still has a considerable amount of heat. According to the older proposal, the heat from the condensate is fed into the heating of the drying system via a heat exchanger, if required. Another alternative is to use a block-type thermal power station if there is an opportunity due to the proximity.

If, as an alternative, the drying is to be heated with flue gas, the filtered and optionally desulphurized and / or denitrified flue gas is fed into the drying process before it is fed into the chimney. When the dryer is heated, the flue gas also loses part of its heat content. It cools down. This can impair the natural smoke evacuation in the chimney. If the flue gas vent is endangered as a result, a fan is preferably provided in the chimney with which the flue gas vent is increased. Optionally, the fan is also located in a by-pass line to the flue gas duct in the chimney. For this purpose, two openings in the chimney wall lying one above the other are sufficient, which are connected via a gas line with a sufficient cross-section and a fan in this by-pass line. In addition, flaps are provided with which openings for the by-pass line can be closed or opened so that the path into the by-pass line can be closed for the flue gas or the entry into the by-pass line can be opened. At the same time, a flap is provided in the chimney with which the chimney can be closed between the two openings for the by-pass line to force the flue gas into the by-pass line, or can be opened when the path through the Chimney should be released again. The flaps can be operated if, for example, too low a flue gas speed is measured in the chimney and it becomes clear that the chimney draft / flue gas exhaust is too low. After the by-pass line has been opened, the flaps are operated again to close the by-pass line when there is again sufficient chimney draft / smoke gas extraction without the by-pass line and the fan provided therein.
There is a minimum flue gas velocity / minimum chimney draft for every chimney, which ensures that there is sufficient combustion in the furnace. In the event of insufficient combustion, poisonous carbon monoxide is formed and, if oxygen is in, explosive carbon monoxide.

• -sämtlicher Klärschlamm wird bis zu einem TR-Gehalt solarthermisch getrocknet, der oberhalb der Leimphase liegt. Bei diesem TR-Gehalt entfallen die oben geschilderten Probleme auf dem Wege in die Feuerung. Zugleich hat der Klärschlamm einen Brennwert/Heizwert, der zumindest in der Wirbelschichtfeuerung/Ofens des Emscherklärwerkes Bottrop für eine selbstgängige Verbrennung sorgt. Bei zu hohem Heizwert kann kurzfristig mittels direkter Wasserzugabe in den Wirbelschichtofen eine Kühlung erfolgen.
• -der Klärschlamm erreicht beim solarthermischen Trocknen nur einen in der Leimphase liegenden TR-Gehalt, der auf dem Förderweg des Klärschlammes zur Wirbelschichtfeuerung/Ofen festgestellt wird und hat noch keine wesentliche Verklumpung oder Verdichtung durch mechanische Belastung erfahren. Dann wird der Klärschlamm zu einer ergänzenden Trocknung der Solarthermischen Trockung zurück geführt.
• -der Klärschlamm erreicht beim solarthermischen Trocknen nur einen in der Leimphase liegenden TR-Gehalt und hat noch keine wesentliche Verklumpung oder Verdichtung durch mechanische Belastung erfahren und kann/soll nicht in die solarthermische Trocknung zurück geführt werden. Zugleich hat der Klärschlamm unter Berücksichtigung einer Zumischung von Asche noch einen für eine selbstgängige Verbrennung ausreichenden TR-Gehalt. Dann ist vorzugsweise eine Vermischung des Klärschlammes mit Flugasche vorgesehen, so dass die Klebrigkeit des Klärschlammes aufgehoben wird und der Klärschlamm trotz des in der Leimphase liegenden TR-Gehaltes der Wirbelschichtfeuerung/Ofen weiter zugeführt werden kann.
• -der Klärschlamm wird auf unterschiedliche TR-Gehalte gebracht, wobei die TR-Gehalte entweder a)unterhalb (zum Beispiel ohne unterstützende Beheizung beim Trocknen oder nur mechanisch entwässert) oder b)innerhalb (durch solarthermische Trocknung) der Leimphase des Klärschlammes bei einem Wert liegen, bei dem noch eine selbstgängige Verbrennung des Klärschlammes in einer Wirbelschichtfeuerung gewährleistet ist. Hierbei wird wahlweise Filterasche/Flugasche zugemischt. Die beiden Fraktionen werden getrennt bis vor den Wurfbeschicker der Wirbelschichtfeuerung/Ofen gefördert. Dort ist eine Pufferung der beiden Klärschlammfraktionen vorgesehen. Als Puffer dienen Silos/Vorlagen/Behälter, in denen die betreffende Klärschlammfraktion eingefüllt wird. Es wird aber nur die selbstgängig brennbare Fraktion nach Bedarf abgezogen und in die Wirbelschichtfeuerung aufgegeben.
• -der Klärschlamm wird auf unterschiedliche TR-Gehalte gebracht, wobei die TR-Gehalte entweder
  • a)unterhalb (zum Beispiel ohne unterstützende Beheizung beim Trocknen oder nur mechanisch entwässert) oder
  • b)oberhalb (durch solarthermische Trocknung) der Leimphase des Klärschlammes bei einem Wert liegen, bei dem eine Mischung mit der
  anderen Klärschlammfraktion herbeigeführt wird, die noch selbstgängig in einer Wirbelschichtfeuerung verbrennt. Die beiden Fraktionen werden getrennt bis vor die Beschickung/Wurfbeschicker der Wirbelschichtfeuerung/Ofen gefördert. Dort ist eine Pufferung der beiden Klärschlammfraktionen vorgesehen. Als Puffer dienen Silos/Vorlagen/Behälter, in denen die betreffende Klärschlammfraktion eingefüllt wird. Nach dem älteren Vorschlag werden aus beiden Silos/Vorlagen/Behältern Klärschlamm-Mengen in einem Verhältnis abgezogen, die zu der vorstehenden, selbstgängig in der Wirbelschichtfeuerung verbrennenden Mischung führen. Bezogen auf die Wirbelschichtfeuerung/Ofen im Emscherklärwerk Bottrop hat die Mischung dann einen TR-Gehalt von mindestens 52Gew%.
• -der Klärschlamm wird auf unterschiedliche TR-Gehalte gebracht, wobei die TR-Gehalte entweder unterhalb (zum Beispiel ohne unterstützende Beheizung beim Trocknen oder nur mechanisch entwässert) oder trotz solarthermischer Trocknung in der Leimphase des Klärschlammes liegen. Der Klärschlamm mit dem innerhalb der Leimphase liegenden TR-Gehalt und wird mit Asche vermischt. Dabei ist der TR-Gehalt so hoch, dass der Klärschlamm trotz der Aschezumischung noch selbstgängig in der Wirbelschichtfeuerung brennt. Mindestens die Klarschlammfraktion mit der Aschezumischung wird bis vor den Wurfbeschicker der Wirbelschichtfeuerung/Ofen gefördert. Dort ist eine Pufferung bzw. Bevorratung vorgesehen. Als Puffer/Bevorratung dienen Silos/Vorlagen/Behälter, in denen die betreffende Klärschlammfraktion eingefüllt wird und so viel Klärschlamm fasst, dass damit vorkommende Schwankungen in der Klärschlammzuführung ausgeglichen werden. Nach dem älteren Vorschlag wird dann nur die Klärschlammfraktion mit der Aschezumischung nach Bedarf abgezogen und über die Beschickungsvorrichtung/Wurfbeschicker in die Wirbeschichtfeuerung aufgegeben.

The older proposal allows different approaches, in particular:

• - All sewage sludge is solar-thermally dried up to a DR content that is above the glue phase. With this TR content, the problems described above do not occur on the way to the furnace. At the same time, the sewage sludge has a calorific value / calorific value that ensures automatic combustion at least in the fluidized bed furnace / furnace of the Emscher sewage works in Bottrop. If the calorific value is too high, cooling can be carried out for a short time by adding water directly to the fluidized bed furnace.
• - During solar thermal drying, the sewage sludge only reaches a DR content in the glue phase, which is determined on the conveyance path of the sewage sludge to the fluidized bed furnace / furnace and has not yet experienced any significant clumping or compression due to mechanical stress. Then the sewage sludge is fed back to a supplementary drying of the solar thermal drying.
• - During solar thermal drying, the sewage sludge only reaches a DR content in the glue phase and has not yet experienced any significant clumping or compression due to mechanical stress and cannot / should not be returned to solar thermal drying. At the same time, the sewage sludge has one more for one, taking into account the addition of ash self-combustion sufficient dry matter content. Mixing of the sewage sludge with fly ash is then preferably provided so that the tackiness of the sewage sludge is eliminated and the sewage sludge can continue to be fed to the fluidized bed furnace / furnace despite the TR content in the glue phase.
• -the sewage sludge is brought to different DR contents, whereby the DR contents are either a) below (for example without auxiliary heating during drying or only mechanically dewatered) or b) within (through solar thermal drying) the glue phase of the sewage sludge at one value , in which an automatic combustion of the sewage sludge is guaranteed in a fluidized bed furnace. Here, either filter ash / fly ash is mixed in. The two fractions are conveyed separately up to the throw feeder of the fluidized bed furnace / furnace. Buffering of the two sewage sludge fractions is planned there. Silos / templates / containers, in which the relevant sewage sludge fraction is filled, serve as buffers. However, only the self-combustible fraction is withdrawn as required and fed into the fluidized bed furnace.
• -the sewage sludge is brought to different TR contents, whereby the TR contents are either
  • a) below (for example without auxiliary heating during drying or only mechanically dewatered) or
  • b) above (by solar thermal drying) the glue phase of the sewage sludge at a value at which a mixture with the
  other sewage sludge fraction is brought about, which still burns independently in a fluidized bed furnace. The two fractions are conveyed separately up to the feeder / throw feeder of the fluidized bed furnace / furnace. Buffering of the two sewage sludge fractions is planned there. Silos / templates / containers, in which the relevant sewage sludge fraction is filled, serve as buffers. According to the older proposal, sewage sludge quantities are withdrawn from both silos / receivers / containers in a ratio that leads to the above mixture, which burns automatically in the fluidized bed furnace. In relation to the fluidized bed furnace / furnace in the Emscherklärwerk Bottrop, the mixture then has a dry matter content of at least 52% by weight.
• -the sewage sludge is brought to different DR contents, whereby the DR contents are either below (for example without auxiliary heating during drying or only mechanically dewatered) or despite solar thermal drying in the glue phase of the sewage sludge. The sewage sludge with the TR content lying within the glue phase and is mixed with ash. The DR content is so high that the sewage sludge still burns independently in the fluidized bed furnace despite the addition of ash. At least the clear sludge fraction with the ash admixture is conveyed up to the throw feeder of the fluidized bed furnace / furnace. Buffering or storage is provided there. Silos / storage tanks / containers are used as buffers / storage facilities, in which the relevant sewage sludge fraction is filled and holds so much sewage sludge that any fluctuations in the sewage sludge supply are compensated for. According to the older proposal, only the sewage sludge fraction with the ash admixture is withdrawn as required and fed into the fluidized bed furnace via the charging device / throw feeder.

• -ungleichmäßiger Sonneneinwirkung/Schattenlage
• -Schwierigkeiten in der gleichmäßigen Ausbreitung des Klärschlammes
• -Schwierigkeiten beim Wenden des Klärschlammes, um nach einer Abtrockung der Oberfläche die unteren Bereiche einer verstärkten Trockung zuzuführen

With just solar drying, uneven drying can result, e.g. with

• -uneven exposure to the sun / shade
• -Difficulties in the uniform spread of the sewage sludge
• -Difficulties in turning the sewage sludge, so that the lower areas are subjected to increased drying after the surface has dried

A comprehensive moisture measurement can be used to ensure that there are no areas with insufficient drying. It may be sufficient if the moisture measurement takes place at intervals on the surface of the sewage sludge layer. Even a visual inspection can be meaningful for the experienced operating personnel. A moisture measurement with a moisture measuring device is preferably always provided.

• -auf der Klärschlammoberfläche
• -im Klärschlamm
• -unmittelbar
• -mittelbar
• -durch Probennahme und Messung an oder in der Probe

The moisture measurement can be done in different ways:

• -on the sewage sludge surface
• -in sewage sludge
• -right away
• - indirectly
• -by taking samples and measuring on or in the sample

The distances between two measuring points on / in the sewage sludge are preferably at most 1 m, even more preferably at most 0.5 m and most preferably at most 0.25 m. The moisture measurement can take place in the upper half of the layer, preferably in the lower half of the layer, even more preferably in the lower third of the layer.

• -dabei die jeweilige Zeit und/oder
• -die Sonneneinstrahlung und/oder
• -die Innentemperatur/Außentemperatur und/oder
• -die Temperatur an den Messstelle und/oder
• -die Luftfeuchtigkeit und/oder
• -den Luftaustausch mit der Umgebung und/oder
• -die Lage der Messstelle

aufzuzeichnen. Neben der Feuchtigkeit hat die Temperatur in der Klärschlammschicht besondere Bedeutung.It is advantageous to record all measurements with a computer and

• - the respective time and / or
• -the sun exposure and / or
• - the indoor / outdoor temperature and / or
• - the temperature at the measuring point and / or
• -the humidity and / or
• - the exchange of air with the environment and / or
• -the location of the measuring point

to record. In addition to the humidity, the temperature in the sewage sludge layer is of particular importance.

As explained above, the moisture content is used to determine whether the sewage sludge is in the glue phase or below the glue phase or above the glue phase.

Alternatively, the stickiness of the sewage sludge can also be measured directly by moving a measuring tool through a mechanically loaded sewage sludge sample under certain conditions and measuring the resistance to the movement. The stickiness of the sewage sludge can also be measured in situ if the mechanical load that triggers the stickiness is generated at the same time as the measurement. In addition, all other conditions that can influence the measurement results should be comparable. This includes in particular the speed of the measuring tool and the temperature. The mechanical load depends on the shape of the measuring tool and the resulting resistance to movement in the sewage sludge. When the measuring tool is pulled, the pulling force can be measured. When the measuring tool is pushed, the compressive force can be measured. The tensile force or compressive force can be compared with other measured values of an advantageous drying, which are obtained in the form described above.

The measuring tool can have different shapes. When measuring the resistance to movement in a mechanically preloaded, for example pressed, sewage sludge sample, the tool can have the shape of a knife or a similar shape that finds only slight resistance to movement in the sewage sludge. If, on the other hand, the movement of the measuring tool is to cause mechanical stress on the sewage sludge, a shape is required that causes a corresponding resistance to movement.

Optionally, sample quantities can also be used for a mere pressure test. The amount of sample is placed between a movable plunger and a base so that actuation of the plunger causes the sample to spread. The propagation takes place under certain conditions, so that the propagation or the force required to achieve the propagation can be measured and compared with other measurement results that have arisen with an advantageous drying. In addition, it is advantageous to inspect the spread of the compressed sample: If sewage sludge is deformed under low pressure, swelling to the side and moving quickly, the sewage sludge is below the glue phase. If the sewage sludge sample shows a coherent structure under the pressure, which does not break open at the edges, but merely deforms outwards, then the sewage sludge examined is in the glue phase. If the sewage sludge sample breaks down into individual structures under pressure, the sewage sludge is above the glue phase.

Optionally, a screw conveyor or another device can be used to measure the stickiness, the operation of which is endangered by the glue phase. With increasing drying, the friction in a screw conveyor changes and with it the necessary drive power. The necessary drive power increases. The consequence is an increased power consumption of an electric drive motor. In this respect, the power consumption of the electric drive motor can also be used as a measured variable for the TR content of the sewage sludge.

For the TR determination of the sewage sludge, it is preferred not to use a screw conveyor measuring screw that is identical to a screw conveyor with which the sewage sludge can be transferred to the feeder of the fluidized bed furnace / furnace. The screw conveyor provided for the measurement can be much smaller. Insofar as one of a conveying device is used for the transfer of the sewage sludge, which according to Art a twin screw extruder, a single screw is preferably provided as the measuring screw, in which clumping and solidification can occur much more quickly.

• -Gewichtsbestimmung
• -Beaufschlagung mit Ultraschall
• -Beaufschlagung mit elektrischer Spannung
• -Stromdurchleitung
• -induktive Messung
• -Messung der kapazitven Eigenschaft des Klärschlammes

Other methods / devices that react to changes in the moisture content are also suitable for measuring moisture. This can be for example

• -Weight determination
• - Application with ultrasound
• - Application of electrical voltage
• -Current transmission
• -inductive measurement
• -Measurement of the capacitive properties of the sewage sludge

The sewage sludge samples used for the TR determination can be returned to the sewage sludge spread out for drying.

• -auf die Temperatur mit Hilfe einer Bodenheizung
• -auf die Raumfeuchte durch Belüftung, gegebenenfalls durch Eintragen von Umgebungsluft
• -durch Wenden des Klärschlammes in der Solartrockung und gegebenenfalls andere Verteilung des Klärschlammes beim Wenden
• -Zugabe von Filterasche/Flugasche

The recording of the measurement results from the TR determination and their comparison allows conclusions to be drawn about the further course of the drying process. A reference curve can be created as a target curve, with which new measurement results can be compared, from the measurement results of a drying process with a good course (advantageous drying). In the event of significant deviations in the new measurement results, the further drying process can be influenced in order to bring the further measurement results close to the reference curve. Influence can be exerted on all framework conditions, for example

• - on the temperature with the help of underfloor heating
• -to the room humidity through ventilation, if necessary through the introduction of ambient air
• -by turning the sewage sludge in the solar drying and possibly other distribution of the sewage sludge when turning
• - Addition of filter ash / fly ash

A sewage sludge is preferably produced which is dried as evenly as possible in all areas.

Advantageously, the reference curve can also be used to make the course of the drying process predictable at other points on the basis of fewer selected measuring points or to control the course of the drying process with a few measuring points. In extreme cases, a single measuring point can be sufficient to foresee or control the overall drying process.

The measurements can be carried out continuously or at intervals.

With continuous measurement, measurement results can be stored continuously, but also discontinuously.

All commercially available measuring devices can be used for all measurements. Measuring devices whose measuring results are electronically generated and can therefore be saved particularly easily are advantageous.

The generation of electronic measurement results occurs automatically with electronic measurement devices, so that a conversion of mechanical measurement results is unnecessary. Electrical probes are suitable for measuring moisture. The more humid the sewage sludge, the stronger a current can flow from the probe into the sewage sludge. With the appropriate calibration, the moisture in the sewage sludge can be read from the current flow. The same also applies to the other measurement methods with current / voltage / capacitive behavior explained above.

• -von denen zum Beispiel die Geradführung für die Längsbewegung zugleich die Geradführung für die Querbewegung verfahrbar trägt und
• -wobei die Geradführung für die Querbewegung die Messeinrichtung verfahrbar trägt und
• -wobei die beiden Bewegungen mit elektrischen Schrittschaltmotoren erzeugt werden, deren Bewegungsimpulse/Schritte vom Rechner vorgegeben werden bzw. vom Rechner gespeichert werden.

The temperature can also be measured with electrical measuring devices, because as a conductor heats up, its resistance to current changes. Here, too, the solar radiation can be measured electrically, with a standard solar cell. The stronger the solar radiation, the more electricity is given off by the solar cell. If there are construction-specific features, these can be taken into account with a computer-aided measurement.
The position of the measuring points can also be determined electrically if a moisture measurement is to be carried out during drying. This can be done, for example, by moving the measuring device in two cross-shaped linear guides,

• -of which, for example, the straight-line guide for the longitudinal movement also carries the straight-line guide for the transverse movement and can be moved
• -wherein the straight guide for the transverse movement carries the measuring device movably and
• -Where the two movements are generated with electric stepping motors, the movement impulses / steps of which are specified by the computer or are stored by the computer.

The straight guides are comparable to the X-axis and Y-axis in the coordinate system, so that the steps on these axes contain an exact position determination. With the usual operating programs of computers, every storage of data takes place at the same time with a time indication.

Advantageously, several or all of the above-explained measuring devices can be combined in a single device which is moved with the two linear guides and the stepping motors.

The measuring probes for moisture measurement can be inserted into the sewage sludge for each measurement process or moved through the sewage sludge while remaining in the sewage sludge. When inserting the probes into the sewage sludge as well as with the permanent movement of the probes through the sewage sludge, knife-like probes that easily cut through the sewage sludge can be advantageous.
It is also advantageous to clean the measuring probes for the moisture measurement at intervals on the surface.
For this purpose, brushes can be provided, for example, which grip the probes from two sides in order to process the surface.

The sufficiently dried sewage sludge is discharged from the solar drying. For example, conventional clearing devices, in particular wheel loaders, can be used for this purpose. Optionally, computer-controlled clearing devices are also used. The clearing devices transfer the dried sewage sludge to conveyor systems, in particular conveyor belts, trough chain conveyors, pipe chain conveyors and screw conveyors.

The current TR content is preferably determined either through the moisture measurements during the drying process and / or through a moisture measurement of the sewage sludge on the conveying device. Optionally, the moisture measurement of the sewage sludge can be limited to the measurement on the conveyor.

The humidity measurement is important because the humidity can change for various reasons. In addition to the reasons already listed above in connection with solar drying, these include weather and seasons, technical problems such as faults in the floor heating described above.

The moisture measurement of the sewage sludge on the conveyor can take place like the moisture measurement during solar drying; Contactless above the sewage sludge or on the sewage sludge surface or in the sewage sludge itself. While the measuring devices are preferably brought to the measuring point for solar drying or solar thermal drying of the sewage sludge, the measuring devices are preferably permanently located there when measuring the sewage sludge on the conveyors. This allows permanent monitoring of the TR content. The moisture measurement of the sewage sludge on the conveying device includes, as with the moisture measurement in solar drying / solar thermal drying, a storage of the measured values and a comparison of measured values with older measured values of an advantageous drying and, if necessary, a change in the drying conditions.

The measured values can be used to decide whether and how the sewage sludge should be further processed before it is fed into the fluidized bed furnace / furnace.

Furthermore, further drying can take place in a facility that is independent of the solar thermal drying and / or the sewage sludge can be mixed with an additive.

For further drying, the exhaust gases from the
Find fluidized bed combustion / furnace use. This can optionally be done in a heated rotating drum.
It is advantageous to design the rotating drum with two shells, to guide the exhaust gases through the cavity between the two shells and to guide the sewage sludge through the center of the rotating drum. As a result, the sewage sludge is indirectly heated and the risk of the sewage sludge igniting due to the exhaust gases is prevented.

The inside of the rotating drum is preferably provided with blades / guide plates which constantly turn the sewage sludge on its way through the rotating drum. This counteracts agglomeration of sludge particles. If, however, sewage sludge particles agglomerate to coarse grain sizes as a result of drying, which are undesirable for the fluidized bed furnace / furnace, or if already agglomerated / clumped sewage sludge is produced, the coarse particles are preferably screened out and crushed.
The screening can advantageously be achieved at the same time by using a sieve drum as a rotating drum. The sieve drum has a sieve jacket inside. The small particles fall through the screen jacket and are conveyed further in the direction of the fluidized bed furnace / furnace. The large particles remain on the sieve and exit the rotating drum at a different point than the small particles. This makes it easy to separate the small particles from the large particles. The small particles are simply collected separately from the large particles at the exit point and carried on. The large / agglomerated / clumped particles are preferably comminuted with a before they are fed back to the sewage sludge treatment.
Simple devices from the processing of soils are suitable for crushing. Suitable devices include star screens with two or more shafts on which star-shaped arms sit. The stars mesh with each other like gears and crush any coarse sewage sludge particles that get between the stars.

The sieve drum is preferably arranged on the conveying path between the solar thermal drying and the fluidized bed furnace / furnace as close as possible to the solar thermal drying. Alternatively, the sludge treatment process can also take place in the hall / building of the solar thermal drying.

When using additives for mixing with the sewage sludge, the filter ash from the flue gas filter of the fluidized bed furnace / furnace can be used. The filter ash is mixed into the sewage sludge and binds the moisture very strongly to the particle surface of the sewage sludge.

For this it may be sufficient to first add the filter ash to the sewage sludge and then to feed both to a mixer / sieve drum. The filter ash can also run into a mixer / sieve drum together with the sewage sludge. Suitable mixers have one or more rotating shafts with mixer arms mounted on them. The rotating drum is also a suitable mixer. The heated rotating drum / sieve drum then combines the mixer function and the dryer function. However, a separation of the various functions can also be provided.

In winter, the introduction of flue gases from the fluidized bed furnace / furnace can also be advantageous in order to keep the rotary drum at a temperature sufficient to function as a mixer. A small part of the exhaust gases from the fluidized bed furnace / furnace is then sufficient. The exhaust gases are then preferably branched off from the cleaned flue gas flow. This can be done with a flue gas line with which the flue gas is introduced into the mixer at one end and withdrawn at the other end and returned to the chimney. It is beneficial if there is an induced draft in the return line, which sucks in the flue gases on one side and pushes them towards the chimney on the other side.

Optionally, the mixer can also have a dryer function at the same time. To do this, more flue gas can be fed to the mixer. Optionally, instead of heating with flue gas, as with solar thermal drying, heating with condensate heat from the steam turbine downstream of the fluidized bed furnace / furnace is provided. Alternatively, the use of a combined heat and power plant is provided.

The amount of filter ash added is adapted to the moisture content of the sewage sludge. In the case of high humidity and high demand for filter ash, the amount of filter ash added can be, for example, up to 10% by weight, based on the total amount of sewage sludge and filter ash. If there is little need for filter ash, the addition of filter ash can be reduced accordingly. Dosing is carried out gravimetrically, for example.

The rotary drum is preferably designed in terms of its heating power and the absorption of filter ash so that in winter, when solar drying is inefficient, it can directly absorb the sewage sludge from the sewage sludge dewatering, bypassing the solar drying, and process it as fuel for the fluidized bed furnace / furnace.

At least one silo is provided on the conveying path to the fluidized bed furnace / furnace, in which a sufficient amount of sewage sludge can be compensated for to bridge fluctuations in the sewage sludge flow. Preferably, at least two silos are provided as close as possible to the throw feeder of the fluidized bed furnace / furnace, which can be charged with differently dried or only mechanically dewatered sewage sludge, with sewage sludge being stored in one silo, the dry matter content of which is below the glue phase, and in the other Silo sewage sludge is stored whose dry matter content is in the glue phase and above the glue phase. According to the older proposal, sewage sludge can be withdrawn from both silos together and fed into a twin screw conveyor. Any desired mixing ratio can be set, for example by gravimetric metering of the discharge quantities, so that the mixture emerging from the twin screw conveyor ensures advantageous combustion in the fluidized bed furnace / furnace. The twin screw conveyor transfers the sewage sludge to the throw feeder. Alternatively, the furnace can also be loaded directly from the respective silo without mixing.

If there is also sewage sludge with an ash content, it can be advantageous if a separate silo is provided for this sewage sludge.

Instead of sewage sludge with a dry matter content above the glue phase, a sewage sludge mixed with ash can also be used, the calorific value of which / The calorific value is sufficient for independent combustion in the fluidized bed furnace / furnace.

With a higher calorific value / calorific value, the sewage sludge mixed with ash can also be mixed with sewage sludge whose calorific value / calorific value is not sufficient for independent combustion. In the mixture, however, the proportion of sewage sludge with the lower calorific value / calorific value is limited in such a way that the mixture still burns by itself.

A twin screw conveyor is preferably provided for mixing sewage sludge from the various silos / receivers / containers.
The twin screw conveyor has two intermeshing screws rotating in a housing in the manner of a twin screw extruder. The sewage sludge is fed through a feed hopper in the housing. Both screws can rotate in the same direction. The screws preferably rotate in opposite directions, so that the sewage sludge placed on top of the screws is drawn in between the screws, comminuted and mixed. At the same time, the twin screw conveyor can form a barrier with the sewage sludge it transports, so that neither ambient air can enter the fluidized bed furnace / furnace in an uncontrolled manner, nor can gases from the combustion chamber enter the environment.
The twin screw conveyor can rise in the conveying direction, but it can also be inclined or arranged horizontally.
Instead of the double screw conveyor, a single screw conveyor or a trough chain conveyor is also conceivable.

As long as the silos and the non-frost-proof parts of the system are enclosed, there is no problem in winter. For example, the parts that are not frost-proof (for example the silos) of the system can be housed next to the fluidized bed furnace / furnace in the furnace hall. Preferably, the parts of the plant that are not housed in the furnace hall and are at risk of frost are made heatable. Even different temperatures can prevent sewage sludge from leaking out of the silos. The exhaust gases from the fluidized bed furnace / furnace can also be used for heating.

The silos / templates / containers serve as a buffer in the event of a fluctuating production volume of treated sewage sludge. The fluidized bed furnace / furnace must be run continuously. Fluctuating operation is only possible to a limited extent for the fluidized bed furnace / furnace. The processed sewage sludge is fed to the silos at the top and drawn off from the silos at the bottom.

The present invention follows on from the earlier proposal. That is to say, the invention has set itself the same task as an older proposal combined with the aim of economic and / or technological improvement in some relevant points.

• Die Erfindung betrifft auch die
• Aufbereitung von Klärschlamm für die Verbrennung in einem Ofen, vorzugsweise in einer Wirbelschichtfeuerung, wobei eine Entwässerung erfolgt und der entwässerte Klärschlamm anschließend getrocknet wird, wobei die Trocknung vorzugsweise eine Solartrocknung ist, wobei höchst bevorzugt die Solartrockung zugleich mit einer von der Witterung unabhängigen Beheizung versehen ist, mit der bei nachlassender Sonnenstrahlung eine gewünschte Trocknung aufrecht erhalten werden kann bzw. ein gewünschter Trocknungsverlauf unabhängig von der Sonneneinstrahlung gewährleistet ist, wobei für die zusätzliche Beheizung vorzugsweise , vorzugsweise industrielle , Verwendung findet, wobei für die Solartrocknung vorzugsweise eine Einhausung vorgesehen ist, wobei noch weiter bevorzugt eine durchsichtige Einhausung vorgesehen ist, wobei der Klärschlamm vorzugsweise zur Trocknung auf dem Boden ausgebreitet und/oder in Abständen gewendet wird.

This is achieved with the features of the present main claim. The subclaims describe preferred exemplary embodiments. In detail:

• The invention also relates to
• Processing of sewage sludge for incineration in a furnace, preferably in a fluidized bed furnace, where dewatering takes place and the dewatered sewage sludge is then dried, where the drying is preferably a solar drying, with the most preferred solar drying also being provided with a heating that is independent of the weather , with which a desired drying can be maintained when the solar radiation subsides or a desired drying process is ensured independently of the solar radiation, whereby preferably, industrial use is made for the additional heating, whereby an enclosure is preferably provided for the solar drying, whereby still further preferably a transparent housing is provided, the sewage sludge preferably being spread out on the ground for drying and / or being turned over at intervals.

The housing can also be an enclosure, also the size of a house or the size of a hall. The larger the enclosure, the more advantageous solar drying is.

• -die Solartrocknung mit einer Bodenheizung kombiniert ist und/oder
• -die Solartrocknung mit einer zusätzlichen Beheizung von oben kombiniert ist, vorzugsweise mit einer Zuführung von Warmluft und/oder inertem, warmem Heizmedium kombiniert ist und/oder
• -der Klärschlamm mit Trocknungsmittel gemischt wird und/oder
• -mindestens zwei Klärschlammfraktionen in den Ofen aufgegeben werden, von denen eine Klärschlammfraktion sich unterhalb der Leimphase befindet und die andere Klärschlammfraktion sich oberhalb der Leimphase befindet.

Preferably is

• -The solar drying is combined with underfloor heating and / or
• the solar drying is combined with additional heating from above, preferably combined with a supply of warm air and / or an inert, warm heating medium and / or
• -the sewage sludge is mixed with desiccant and / or
• - at least two sewage sludge fractions are fed into the furnace, of which one sewage sludge fraction is below the glue phase and the other sewage sludge fraction is above the glue phase.

The additional heating can make the system independent of the weather and / or cause power peaks in sewage sludge drying, which would not be possible without the additional heating.

For the additional floor heating according to the invention, warm air and / or inert warm gas is preferably passed through the floor into the sewage sludge.

A floor for floor heating is advantageous which is provided with passage openings, preferably slot-shaped openings, for warm air and / or inert warm gas or other heating means. The bottom can at the same time form part of the feed for the heating means, namely the top of the feed.

However, the floor can also be provided with underfloor heating and, for use, can be flowed through with warm, liquid heating medium, in particular with hot water.

The additional heating can also be done from above. Then at least one heating element is arranged above / above the sewage sludge in the housing and hot air or other heating means, especially hot water, flows through it, so that the gases emerging from the sewage sludge as well as other gases enclosed by the housing are indirectly heated and more moisture is also heated these gases can be discharged. At the same time, the sewage sludge is heated with the additional heating from above as well as by the additional heating from below, so that more moisture is expelled from the sewage sludge and the gas accumulation increases. Because of the flammability of various gas constituents, it can be advantageous to fill the space above the sewage sludge in the housing permanently or temporarily, either completely or partially, with an inert gas that is non-flammable under the given circumstances. The filling depends on whether the gas / air mixture in the housing reaches a critical order of magnitude and / or a critical ignition temperature. Both can be measured. As long as the critical order of magnitude and / or the critical ignition temperature is not reached, a combustible air / gas mixture can be advantageous in order to burn it in a controlled manner. Burning prevents unpleasant odors in the system and unpleasant odors in the area. In addition, the heat content can be used by introducing the air / gas mixture into the furnace.

As explained above, when drying, the sewage sludge should be avoided in the glue phase. A sewage sludge that is above the glue phase is called an overdried sewage sludge; a sewage sludge, which is located under the glue phase, as an underdried sewage sludge. Depending on the operating conditions, it can be advantageous to produce an over-dried sewage sludge or an under-dried sewage sludge. This can include an intermittent drying, in which sewage sludge that has been underdried for a period is produced and then sewage sludge that is undried for a period is produced. It is advantageous to use several silos, from which, for example, underdried sewage sludge is moved to one silo and overdried sewage sludge is moved to another silo. The sewage sludge can then be withdrawn from both silos in such proportions and mixed with one another in front of the furnace to produce sewage sludge that can still be conveyed.

Foreign sludge can advantageously also be added. A sewage sludge produced in a plant is referred to as foreign sludge. In principle, it is possible to mix the foreign sludge with your own sludge from the system before it is fed into a silo. The sewage sludge produced in the plant itself is referred to as own sludge. In principle, it is also possible to create alternating layers of foreign sludge and own sludge in a silo. This will then be taken into account by quickly changing the loading and operating mode of the furnace. It is easier to use a separate silo for each type of sludge.

There are particular advantages if the sewage sludge is first mixed in the furnace. Then it does not depend on the eligibility of the mixture.

• -Asche
• -Kalk
• -übertrockneter Klärschlamm

In addition, it can be economically advantageous if sewage sludge is obtained during the drying process, which is indeed in the glue phase, but can be made into a pumpable sewage sludge by adding drying agents. In this case, no drying agent should be added. At least one drying agent is then preferably selected from the following list of drying agents:

• -Ash
• -Lime
• -overdried sewage sludge

The drying agent can be added in such an amount that a sewage sludge in the glue phase can be conveyed.

In the way explained above, two sewage sludge flows can be mixed with one another, of which one sewage sludge flow is located below the glue phase and the other sewage sludge flow is above the glue phase. If the mixture is made before it is fed into the furnace and if the sewage sludge is capable of being conveyed, then the sewage sludge mixture should be above the glue phase.

If the mixture is first mixed in the oven, then the eligibility of the mixture is irrelevant.

According to the invention, sewage sludge with different properties can also be processed. In addition to the different moisture levels, the different properties relate in particular to different densities and / or different grain sizes.

Fluidized bed furnaces are advantageous as furnaces for incinerating sewage sludge produced according to the invention. These include both ovens with a stationary fluidized bed and ovens with a circulating fluidized bed.

When several different sewage sludge streams are burned in the stationary fluidized bed, it can be advantageous to supply secondary air above the fluidized bed for the combustion of particles there, which are carried beyond the fluidized bed and burn there. An associated increase in the furnace temperature can be counteracted by additional cooling.

An excessive increase in the oven temperature can be counteracted by injecting water. This can be done through prepared lances on the furnace.

It is advantageous for the sewage sludge mixture in a fluidized bed furnace if a separate feed, preferably a separate throw feeder, is provided for each sewage sludge flow / material flow belonging to the mixture.

In the case of a stationary fluidized bed, the position of the fluidized bed and its dimensions and other properties are not only dependent on the combustion air with which a fluidized bed in the furnace is blown from below. It is advantageous if at least one throw feeder of the fluidized bed furnace can be controlled in order to optimize the sewage sludge feed and thus also the fluidized bed.

• -die Anzahl der Klärschlammwürfe pro Zeiteinheit und/oder
• -die Richtung der Klärschlammwürfe in der Horizontalen und/oder in der Vertikalen und/oder
• -die Wurfweite und/oder
• -die Streuung des Klärschlammes,

The controllability can concern:

• -the number of sewage sludge throws per unit of time and / or
• -the direction of the sewage sludge dump horizontally and / or vertically and / or
• -the throwing distance and / or
• -the spreading of the sewage sludge,

• -Paddel und/oder Schaufeln und/oder Pflugscharen an einer Welle befestigt sind und
• -mit der Welle in einem Gehäuse umlaufen und
• -zur Längsrichtung der Welle eine Schrägstellung aufweisen,

so in einer Drehrichtung der Welle eine Mischung des Klärschlammes und zugleich eine Förderwirkung auf den Klärschlamm ausgeübt wird.According to the older proposal, provision was made for a mixer to be provided before loading when sewage sludge was stored or when a silo was arranged in the sewage sludge conveyor line. This particularly applies to the simultaneous removal of different sewage sludge from two silos. According to the older proposal, a twin-screw mixer was provided as the mixer. This is based on the knowledge of forced mixing in a twin screw mixer. In the meantime it has been shown that significantly better mixing results can be achieved with paddle mixers and paddle mixers and ploughshare mixers. These are the mixers of this type

• -Paddles and / or shovels and / or plowshares are attached to a shaft and
• -Rotate with the shaft in a housing and
• - have an inclination to the longitudinal direction of the shaft,

so in one direction of rotation of the shaft a mixture of the sewage sludge and at the same time a conveying effect on the sewage sludge is exerted.

In addition, the paddles and shovels or plowshares can be spaced apart in the longitudinal direction of the shaft in such a way that there is space between the paddles and shovels and plowshares for fixed installations in the housing, with which the mixing effect is increased.

The internals can have an additional cutting and mixing action and preferably in turn have the shape of paddles and / or shovels and / or plowshares.

The paddles have a flat shape.

The shovels and plowshares have curved shapes, which manufacturers expect process advantages to be.

The paddle mixers, paddle mixers and ploughshare mixers are single-axis or double-axis, the double-axis paddle mixers or paddle mixers or ploughshare mixers preferably having intermeshing paddles or shovels or plowshares on the shafts and the internals being arranged outside the area of intermeshing parts.

It is advantageous if the paddle mixers, paddle mixers and ploughshare mixers surround the shafts and / or paddles and / or shovels and / or plowshares with housings which have a dividing joint in the longitudinal direction, which facilitates assembly and disassembly.

Depending on the nature of the paddle mixers, paddle mixers and ploughshare mixers, the focus is on the mixing effect and not the conveying effect. In order to give the sewage sludge a sufficient delivery pressure on the way to the feed, it can be useful to provide a screw conveyor between the paddle mixer or paddle mixer or ploughshare mixer on the one hand and the throw feeder on the other

• Der Ofenbetrieb kann mit der Trocknung und Mischung des Klärschlammes gekoppelt sein.
• Der Ofenbetrieb kann auch von der Trocknung und Mischung des Klärschlammes unabhängig sein.

In particular, the silos explained above open up various possible modes of operation for the furnace:

• The furnace operation can be coupled with the drying and mixing of the sewage sludge.
• The furnace operation can also be independent of the drying and mixing of the sewage sludge.

• -bei der Trocknung und/oder
• -bei der Mischung des Klärschlammes und/oder
• -bei dem Transport des Klärschlammes

Advantageously, the solar thermal sludge drying according to the invention has a wonderful energy balance because solar radiation is free. In addition, there are advantages through industrial use for the additional heating and, if necessary, additional heating points explained above. There are additional heating points:

• -during drying and / or
• - when mixing the sewage sludge and / or
• -in the transport of the sewage sludge

• -mit dem Abgas aus der Verbrennung des Klärschlammes und/oder
• -aus der Ofenkühlung und/oder
• -aus der Dampferzeugung in der Wirbelschichtfeuerung für einen Stromgenerator
• -aus sonstigen Quellen

The one that can be used here may arise

• -with the exhaust gas from the incineration of the sewage sludge and / or
• -from the furnace cooling and / or
• -from the steam generation in the fluidized bed furnace for an electricity generator
• -from other sources

According to the older proposal, the sewage sludge is comminuted with every mixer that the sewage sludge passes through on the way from drying to the kiln.
For the drying and conveying of the sewage sludge, an additional single or multiple crushing can be carried out
of the sewage sludge and / or turning the sewage sludge in the drying device and / or
an additional single or multiple comminution of the sewage sludge on the conveying path from the drying device to the furnace loading may be advantageous.
Milling machines, for example, but also other comminution tools, in particular agricultural tools for plowing and other soil cultivation, are suitable for the comminution and turning of the sewage sludge under the housing. Depending on the size of the housing, these devices can be used immediately or used in a scaled-down replica.

• -einer Trocknungsvorrichtung, wobei die Trocknungsvorrichtung
  • a)mit einem durchsichtigen Gehäuse/Einhausung versehen ist, das die Sonnenstrahlen durchlässt und zumindest einen Regenschutz bildet, vorzugsweise auch eine Trennung gegenüber der Umgebungsluft bildet
  • b)wobei das Gehäuse eine Luft- bzw. Gasaustrittsöffnung besitzt, durch die die im Gehäuse anfallende Luft bzw. Gas entweichen kann, wobei an der Luft- bzw. Gasaustrittsöffnung vorzugsweise ein Filter sitzt, noch weiter bevorzugt die Gasaustrittsöffnung oder der Filter mit einem Gebläse versehen ist, wobei die Ansaugseite des Gebläses zur Luft- bzw. Gasaustrittsöffnung weist
• -mindestens einem Mischer mit einer Zuführungsöffnung für getrockneten Klärschlamm und einer Zuführungsöffnung für Trocknungsmittel, vorzugsweise mit einer gemeinsamen Zuführungsöffnung für Klärschlamm und Trocknungsmittel
• -mindestens einer Fördervorrichtung für Klärschlamm von der Trocknungsvorrichtung zu dem Mischer
• -mindestens einer Fördervorrichtung vom Austritt des Klärschlammes aus der Trocknungsvorrichtung zur Rückführung von Klärschlamm an den Eintritt des Klärschlammes in die Trocknungsvorrichtung
• -einer Weiche in Fördervorrichtung von der Trocknung zum Mischer, an die auch die Fördervorrichtung für die Rückführung des Klärschlammes angeschlossen ist
• -mindestens einer Feuchtigkeitsmessvorrichtung auf dem Förderweg von dem Klärschlammaustritt aus der Trocknung zu der Weiche, wobei die Feuchtigkeitsmessvorrichtung und die Weiche an eine gemeinsame Steuerungsvorrichtung angeschlossen sind, so bei Überschreiten einer vorgegebenen Feuchtigkeit des Klärschlammes die Weiche betätigt wird.

A system composed of, for example, is suitable for carrying out the method described above

• -a drying device, wherein the drying device
  • a) is provided with a transparent housing / housing that lets the sun's rays through and forms at least a rain cover, preferably also forms a separation from the ambient air
  • b) the housing having an air or gas outlet opening through which the air or gas occurring in the housing can escape, a filter preferably being located on the air or gas outlet opening, even more preferably the gas outlet opening or the filter with a fan is provided, the suction side of the fan facing the air or gas outlet opening
• At least one mixer with a supply opening for dried sewage sludge and a supply opening for drying agent, preferably with a common supply opening for sewage sludge and drying agent
• -at least one conveying device for sewage sludge from the drying device to the mixer
• -at least one conveying device from the outlet of the sewage sludge from the drying device for the return of sewage sludge to the inlet of the sewage sludge in the drying device
• -a switch in the conveying device from the drying to the mixer, to which the conveying device for the return of the sewage sludge is also connected
• -at least one moisture measuring device on the conveying path from the sewage sludge outlet from the drying to the switch, wherein the moisture measuring device and the Switches are connected to a common control device, so the switch is operated when a predetermined moisture content of the sewage sludge is exceeded.

The drying device is preferably provided with a heating element for additional heating. The radiator can consist of at least one closed pipe or hose through which heating medium flows. In addition, a slotted floor is optionally provided in the drying device for floor heating, which forms a feed for gaseous heating medium.

According to the older proposal, two mixers are provided on the conveyance path of the sewage sludge from the drying area to the kiln.

The first mixer is a drum screen. The drum sieve not only mixes the sewage sludge with desiccants. The drum sieve also separates oversized particles from the sewage sludge entering the mixer. Even without the mixture, it is advantageous to use the drum screen to separate oversized grains. Oversized grain can also occur if the sewage sludge agglomerates after dewatering.
To return the oversized grain is preferred
a conveying device is provided from the exit of the sewage sludge with oversized grain on the drum screen to the entry of the sewage sludge into the dryer.

According to the older proposal, the second mixer is provided in the sewage sludge conveyor line between the silos and the feed. Here the paddle mixers or paddle mixers or ploughshare mixers have proven to be advantageous.

• zeigt eine Referenzkurve eines optimal förderbaren. Der Schlamm wurde lediglich abgepresst und nicht getrocknet. Aufgrund des hohen Wassergehaltes lässt er sich optimal fördern.
• zeigt eine Referenzkurve eines in die Leimphase getrockneten Klärschlammes
• zeigt eine schematische Darstellung einer Anlage nach dem älteren Vorschlag.

In the drawing, an embodiment of the older proposal is shown schematically:

• shows a reference curve of an optimally fundable. The sludge was only pressed out and not dried. Due to the high water content, it can be pumped optimally.
• shows a reference curve of a sewage sludge dried in the glue phase
• shows a schematic representation of a system according to the older proposal.

with 1 a sewage sludge dewatering with filter presses is shown schematically.
From the drainage 1 the sewage sludge becomes a solar thermal drying process 2 fed. The term "solar thermal" results from a combination of solar drying with heating that is independent of solar radiation.
In the embodiment example belongs to the solar thermal drying 2 a glass greenhouse that can be driven over, the individual panes of which are held in a steel structure. In addition, the greenhouse is connected to a ventilation system, which includes a fan that can draw in ambient air from the outside and the exhaust air and vapors generated by the drying process via a pipe 26th and a biofilter 41 can be discharged into the atmosphere.
The greenhouse is also provided with floor heating. In the exemplary embodiment, the floor of the greenhouse consists of sheet steel, which is designed to be driven on by a front loader, which has the task of distributing sewage sludge in the greenhouse and clearing it away again after drying and transferring it to a conveyor belt 3 to give up.
In the exemplary embodiment, heating pipes are laid under the sheet steel floor, which give off their heat to the sheet steel floor, which in turn gives off the heat to the sewage sludge. The heating pipes are in the embodiment via a line 24 with condensate heat from a steam turbine 22nd fed. The steam turbine 22nd is over a line 25th operated with steam in the boiler system 42 incineration of sewage sludge occurs. The steam drives the steam turbine 22nd by sending most of its inherent energy to the turbine 22nd gives away. On his way through the turbine 22nd the steam relaxes and cools down. At the end, a condensate emerges from the turbine 22nd that still contains residual heat that can be used. In the exemplary embodiment, the major part of the condensate is via a line 23 the boiler system 42 supplied again for renewed evaporation.

Via a heat exchanger 43 and a line 24 the remaining condensate heat is used in the drying system.

The sewage sludge leaves the drying area 2 on a conveyor 3 . The conveyor route 3 is formed in the embodiment of conveyor belts. On the conveyance route 3 finds a moisture measurement with a moisture meter 12th instead of.

• -die Trockung 2 anhand einer Referenzkurve steuert Die zeigt eine Referenzkurve für einen vollständig ausgefaulten Klärschlamm, der mittels einer Membrankammerfilterpresse auf einen TR von 29,45 Gew% abgepresst worden ist und noch nicht getrocknet wurde. Dieser Trocknungsgrad liegt unterhalb der Leimphase des Klärschlammes. Das wird an nachfolgender Prüfung des Klärschlammes deutlich:
  • Mengen von jeweils 0,5 Litern des Klärschlammes werden unter definiertem Druck zu einem Prüfkörper geformt. In den Prüfkörper wird bis zu einer definierten Tiefe eine Platte eingeführt. Anschließend wird die Metallplatte mit einer konstanten Geschwindigkeit aus dem Prüfkörper gezogen. Die zum Herausziehen der Metallplatte benötigte Kraft wird gemessen. Die zeigt, dass sich die Kraft zum Herausziehen der Platte über die Länge der Bewegung in einer hierfür signifikanten Art und Weise verändert. Dieser Schlamm wird als besonders vorteilhafter Schlamm angesehen. Der Schlamm wurde bereits in größeren Mengen in einer vorhandenen Wirbelschichtfeuerung störungsfrei verbrannt. Es gab keine Einschränkungen bei der Förderung des Schlamms mittels Dickstoffpumpe und Schnecken sowie der Vorlage in einem 12m hohen Silo.

The measurement result is sent to a computer 11 given that

• -the drying 2 based on a reference curve, Die controls shows a reference curve for a completely digested sewage sludge which has been pressed to a TR of 29.45% by weight by means of a membrane chamber filter press and has not yet been dried. This degree of drying is below the glue phase of the sewage sludge. This becomes clear from the following examination of the sewage sludge:
  • Quantities of 0.5 liters each of the sewage sludge are formed into a test specimen under a defined pressure. A plate is inserted into the test body to a defined depth. The metal plate is then pulled out of the test specimen at a constant speed. The force required to pull out the metal plate is measured. the shows that the force to pull out the plate changes over the length of the movement in a manner that is significant therefor. This mud is considered to be a particularly beneficial mud. The sludge has already been incinerated in large quantities in an existing fluidized bed furnace without any problems. There were no restrictions on the conveyance of the sludge by means of a thick matter pump and augers or the storage in a 12m high silo.

shows a reference curve for the resulting sludge with ideal solar drying to a DR content of 49% by weight. The TR content shows that the sewage sludge is in the glue phase. With the same production of a test specimen as after and shows the same penetration of a metal plate that the force absorption when pulling the metal plate out of the test specimen increases dramatically. The force absorption decreases sharply over the length of the movement. On average, however, the force absorption remains very high.

To get out of the glue phase, in one embodiment, the sewage sludge has to pass through the drying process 2 intended. This takes place after the sewage sludge emerges from the drying area 2 by returning to the drying process 2 . The older proposal implies that more than one return should be carried out in order to arrive at a desired DR content of more than 60% by weight. In the exemplary embodiment, the computer decides on the return 11 .

As an alternative to returning the sewage sludge, which has been solar-dried, in another embodiment, drying 2 activated underfloor heating. With the floor heating an additional drying of the sewage sludge is achieved.

• -bei Bedarf entscheidet,
  • -- ob und in welchem Umfang der austretende Klärschlamm über eine Leitung unmittelbar einem Silo 6 zugeführt wird. Im Ausführungsbeispiel hat dieser Klärschlamm einen TR-Gehalt von 28 Gew%, in anderen Ausführungsbeispielen einen TR-Gehalt von 25 bis 30Gew%
  • -- ob und in welchem Umfang der austretende Klärschlamm zu einer ergänzenden Trocknung über den Förderweg 13 in die Trocknung 2 zurückgeführt wird.

Both the additional drying by recycling in the first exemplary embodiment and the additional drying by the floor heating provided in the second exemplary embodiment are referred to as overdrying.

• -decide if necessary,
  • - whether and to what extent the discharged sewage sludge via a pipe directly into a silo 6th is fed. In the exemplary embodiment, this sewage sludge has a DR content of 28% by weight, in other exemplary embodiments a DR content of 25 to 30% by weight
  • - whether and to what extent the discharged sewage sludge for additional drying via the conveying route 13th in the drying 2 is returned.

• -- ob und in welchem Umfang eine ergänzende Trocknung normal getrockneten Klärschlammes stattfindet. Eine Trocknung auf einen TR-Gehalt größer 60Gew% wird als Übertrockung bezeichnet. Im Ausführungsbeispiel wird durch Übertrocknung ein TR-Gehalt von 52Gew% und mehr erreicht. Im Ausführungsbeispiel handelt es sich um den Klärschlamm des Emscherklärwerkes in Bottrop, dessen TR-Gehalt für eine selbstgängige Verbindung 52Gew% beträgt.

Der übertrocknete Schlamm wird mit einem TR-Gehalt von mehr als 52Gew% über den Förderweg 31 unmittelbar in ein SilO 5 geleitet.
Der übertrocknete Schlamm mit einem TR-Gehalt zwischen 52 und 60Gew% wird allein in der Wirbelschichtfeuerung 7 verbrannt. Um die Mischung mit dem Schlamm im Silo 6 und die Entstehung eines nicht mehr selbstgängig brennenden Schlammgemisches zu verhindern, wird die am Austrag des Silos 6 vorgesehene gravimetrische Dosierung auf Null gestellt.
Bei einem übertrockneten Schlamm mit einem TR-Gehalt von mehr als 60Gew% findet im Ausführungsbeispiel jedoch eine Mischung mit dem Schlamm aus dem Silo 6 statt. Zur Herstellung der Mischung ist auch das Silo 5 am Austrag mit einer gravimetrischen Dosierung versehen. Der mit beiden Dosierungen erzielte Austrag aus den Silos 5 und 6 läuft mit dem gewünschten, im Ausführungsbeispiel vom Rechner 11 vorgegebenen Mengenverhältnis in den Einlauftrichter eines eingehausten Doppelschneckenförderers 20. Dieser Förderer vermischt die beiden Schlammfraktionen und übergibt sie an einen Wurfbeschicker 21 an der Wirbelschichtfeuerung 7.

• -- ob allein von dem Silo 5 übertrockneter Klärschlamm mit einem TR-Gehalt von 52 bis 60Gew% abgezogen wird oder ob mit einem übertrockneten Schlamm einem TR-Gehalt von mehr als 60Gew% aus dem Silo 5 auch nicht selbstgängig verbrennender Schlamm aus dem Silo 6 abgezogen wird. Dabei stützt sich der Rechner auf eine Füllstandsmessung im Silo 5. Die Füllstandsmessung zeigt, bei welchem Füllstand die Beschickung des Silos 5 von übertrocknetem Klärschlamm mit einem TR-Gehalt von mehr als 60 Gew% (mehr übertrocknet) auf die Beschickung mit einem übertrockneten Klärschlamm von 52 bis 60Gew% (weniger übertrocknet) umgeschaltet worden ist. Entsprechendes gilt für die Umschaltung der Beschickung von weniger übertrocketem Klärschlamm auf mehr übertrocknetem Klärschlamm. Der Rechner 11 kann dann anhand des mit der gravimetischen Dosierung ermittelbaren Austrages feststellen, wann sämtlicher Klärschlamm, der weniger übertrocknet ist, oder sämtlicher mehr übertrockneter Klärschlamm aus dem Silo 5 ausgeflossen ist. Dabei kann mit erheblichem Toleranzbereich gerechnet werden, weil die Wirbelschichtfeuerung 7 nicht sofort gravierend gestört wird, wenn anstelle einer Mischung aus übertrocknetem Klärschlamm und nicht selbstgängig brennbarem Klärschlamm nur noch übertrockneter Klärschlamm verbrannt wird,

oder wenn anstelle von nur weniger übertrocknetem Klärschlamm nur mehr übertrockneter Klärschlamm verbrannt wird,
oder wenn anstelle von mehr übertrocknetem Klärschlamm nur weniger übertrockneter Klärschlamm verbrannt wird,
oder wenn anstelle von nur übertrocknetem Klärschlamm nur eine Mischung aus übertrocknetem Klärschlamm und nicht selbstgängig brennbaren Klärschlamm verbrannt wird.
Die Steuerung der Wirbelschichtfeuerung 7 ist gleichfalls rechnergestützt und reagiert auf Änderungen
Verbrennungszustände und Verbrennungsprodukte und Verbrennungszustände durch Änderung der Brennstoffzuführung und/oder Änderung der Verbrennungsluftzuführung und/oder
Änderung des Wirbelbettes und/oder Änderung der Dampferzeugung.
Ist der Heizwert des Schlammes zu kurzfristig zu hoch, so kann über Lanzen Wasser in den Wirbelschichtofen dosiert werden.
Ist der Heizwert zu niedrig kann eine kurzfristige Anhebung des Heizwertes durch Ölzugabe mittels Öl-Lanzen erfolgen.
Zu den Verbrennungsprodukten gehört auch das Rauchgas, von dem zumindest einige Bestandteile gut messbar sind.

• -- wann von dem Silo 5 (übertrockneter Klärschlamm) auf das Silo 6 (normal solarthermisch getrockneter Klärschlamm und rein mechanisch entwässerter Klärschlamm) umgeschaltet wird und umgekehrt. Für die Umschaltung sind am Eingang der Silos 5 und 6 Schieber vorgesehen, die über den Rechner 11 gesteuert werden. Die Umschaltung von übertrocknetem Klärschlamm auf normal getrockneten Klärschlamm und rein mechanisch entwässerten Klärschlamm ist zugleich mit einer Beendigung der Rückführung von Klärschlamm auf dem Förderweg 13 verbunden. Die Umschaltung vom Silo 6 (normal getrocknetem Klärschlamm und rein mechanisch entwässerten Klärschlamm) auf das Silo 5 (übertrockneter) Klärschlamm ist zugleich mit einer Öffnung der Rückführung auf dem Förderweg 13 verbunden.

Supplementary drying can be useful if drying is inadequate. This can be the case if the desired dry matter content is not achieved due to malfunctions in the drying operation or unfavorable general drying conditions.

• - whether and to what extent additional drying of normally dried sewage sludge takes place. Drying to a dry matter content of more than 60% by weight is referred to as overdrying. In the exemplary embodiment, a DR content of 52% by weight and more is achieved through overdrying. In the exemplary embodiment, it is the sewage sludge from the Emscher sewage treatment plant in Bottrop, the dry matter content of which for a self-running connection is 52% by weight.

The overdried sludge with a DR content of more than 52% by weight is transported over the conveying path 31 passed directly into a SilO 5.
The overdried sludge with a DR content between 52 and 60% by weight is used in the fluidized bed furnace alone 7th burned. To mix with the sludge in the silo 6th and to prevent the formation of a sludge mixture that is no longer self-burning, this is done at the discharge of the silo 6th intended gravimetric dosing set to zero.
In the case of overdried sludge with a dry matter content of more than 60% by weight, however, there is a mixture with the sludge from the silo in the exemplary embodiment 6th instead of. The silo is also used to produce the mixture 5 Equipped with a gravimetric metering at the discharge. The discharge from the silos achieved with both dosing units 5 and 6th runs with the desired, in the exemplary embodiment from the computer 11 specified quantity ratio in the inlet funnel of an enclosed twin screw conveyor 20th . This conveyor mixes the two sludge fractions and transfers them to a throw feeder 21 at the fluidized bed furnace 7th .

• - whether alone from the silo 5 overdried sewage sludge with a dry matter content of 52 to 60% by weight is withdrawn from the silo or whether with overdried sludge a dry matter content of more than 60% by weight is withdrawn from the silo 5 also not self-burning sludge from the silo 6th is deducted. The computer relies on a level measurement in the silo 5 . The level measurement shows the level at which the silo is loaded 5 from overdried sewage sludge with a DR content of more than 60% by weight (more overdried) to the charge with an overdried one Sewage sludge from 52 to 60% by weight (less overdried) has been switched. The same applies to switching the feed from less over-dried sewage sludge to more over-dried sewage sludge. The computer 11 can then use the discharge that can be determined with the gravimetic dosage to determine when all sewage sludge that is less overdried or all more overdried sewage sludge from the silo 5 has flowed out. A considerable tolerance range can be expected because of the fluidized bed combustion 7th there is no immediate serious disruption if instead of a mixture of overdried sewage sludge and sewage sludge that is not self-flammable, only overdried sewage sludge is burned,

or if instead of only less overdried sewage sludge only overdried sewage sludge is incinerated,
or if instead of more overdried sewage sludge only less overdried sewage sludge is incinerated,
or if, instead of only over-dried sewage sludge, only a mixture of over-dried sewage sludge and sewage sludge that is not self-combustible is incinerated.
The control of the fluidized bed combustion 7th is also computer-aided and reacts to changes
Combustion states and combustion products and combustion states by changing the fuel supply and / or changing the combustion air supply and / or
Changing the fluidized bed and / or changing the steam generation.
If the calorific value of the sludge is too high for a short time, water can be dosed into the fluidized bed furnace via lances.
If the calorific value is too low, the calorific value can be increased briefly by adding oil using oil lances.
Combustion products also include flue gas, at least some of which are easily measurable.

• - when from the silo 5 (overdried sewage sludge) on the silo 6th (normal solar thermal dried sewage sludge and purely mechanically dewatered sewage sludge) and vice versa. The silos are at the entrance for switching 5 and 6th Slider provided through the calculator 11 to be controlled. The switchover from over-dried sewage sludge to normally dried sewage sludge and purely mechanically dewatered sewage sludge is at the same time as the end of the return of sewage sludge on the transport route 13th connected. Switching from the silo 6th (normally dried sewage sludge and purely mechanically dewatered sewage sludge) onto the silo 5 (overdried) sewage sludge is simultaneously with an opening of the return on the conveying route 13th connected.

• -bei Bedarf entscheidet, ob und in welchem Umfang welcher Klärschlamm über die Förderwege 40, 3 und 31 unmittelbar den Silos 5 und 6 oder weiter über den Förderweg 3 in eine Drehtrommel 4 geleitet wird. Auch für diese Umschaltung auf dem Förderweg 3 zur Drehtrommel 4 ist auf dem Förderweg 3 eine Weiche vorgesehen.
• -bei Bedarf auch entscheidet, ob und in welchem Umfang in der Drehtrommel 4 Asche zugegeben wird. Die Drehtrommel 4 bildet zugleich einen Mischer, in dem der in die Drehtrommel 4 eingetragene Klärschlamm und die in die Drehtrommel aufgegebene Asche miteinander umgewälzt werden. In anderen Ausführungsbeispielen ist die Drehtrommel zugleich mit Schaufeln versehen, die das Umwälzen fördern.

For switching to the return of the sewage sludge on the conveying route 13th is in the conveyance path 3 a switch provided. To end the return, the switch is reset.

• -If necessary, decides whether and to what extent which sewage sludge via the transport routes 40 , 3 and 31 directly to the silos 5 and 6th or continue along the conveyor route 3 into a rotating drum 4th is directed. Also for this switchover on the conveyor route 3 to the rotary drum 4th is on the way 3 a switch provided.
• -If necessary also decides whether and to what extent in the rotary drum 4th Ash is added. The rotating drum 4th at the same time forms a mixer in which the in the rotary drum 4th registered sewage sludge and the ash fed into the rotary drum are circulated together. In other exemplary embodiments, the rotary drum is also provided with blades that promote the circulation.

• -bei Bedarf auch entscheidet, ob und in welchem Umfang eine Beheizung der Drehtrommel 4 erfolgt. Zur Beheizung wird Rauchgas aus dem Rauchgas der Wirbelschichtfeuerung/Ofen 7 abgezweigt und über eine Leitung 9 der Drehtrommel zuführt.

The ash reduces the stickiness of the sewage sludge if necessary. In the exemplary embodiment, the amount of ash added is up to 10% by weight of the resulting mixture. In other embodiments 0 % To 4% by weight of the resulting mixture.
The filter ash comes from an exhaust filter 9 a fluidized bed furnace / furnace 7th . The feed for the filter ash is denoted by 10. In the feeder 10 there is a silo (not shown) with a dosage for adding ash.

• -If necessary, it also decides whether and to what extent heating of the rotary drum 4th he follows. Flue gas from the flue gas of the fluidized bed furnace / furnace is used for heating 7th branched off and via a line 9 feeds the rotary drum.

The need arises when the solar thermal drying does not come to a desired degree of drying during the first passage of the sewage sludge particles and it is inexpedient to return the sewage sludge particles to the drying process. Then the rotating drum can with part of the hot exhaust gases from the fluidized bed furnace / furnace 7th be heated and a further drying can be achieved on the way. The supply of the exhaust gases to the rotating drum 4th is denoted by 8.

The rotary drum is provided with a double jacket for heating. The flue gas is fed into the cavity of the double jacket and does not come into contact with the sewage sludge. The heating optionally serves as a frost protection, optionally also for additional drying of the sewage sludge in the rotating drum.

In the exemplary embodiment is the rotary drum 4th at the same time designed as a sieve. A filter is advantageous if the sewage sludge particles are on the way from the drying area to the silos 5 and 6th Sewage sludge particles agglomerate to form larger particles or if, for example, coarse particles of screenings (the coarse screenings include, for example, pieces of wood that are normally removed from the wastewater with a rake, but have not been captured by the rake) are contained in the sewage sludge, which no longer for feeding the fluidized bed furnace / furnace 7th or for the silos 5 and 6th that are suitable for screw conveyors and throw feeders. The rotary drum is used to screen the coarse particles 4th lined with a sieve jacket. The sewage sludge is placed in the center of the rotating drum 4th and abandoned the sieve jacket. By turning the rotating drum 4th the sewage sludge is circulated in the sieve jacket. The sewage sludge particles with dimensions smaller than the mesh size of the sieve casing fall through the sieve casing into the cavity between the sieve casing and the surrounding casing of the rotating drum 4th . These particles are in the pipe 31 to the silos 5 and 6th directed. The larger particles are larger than the mesh size of the sieve shell and are screened off as the smaller particles pass through. These particles are transported via a transport route 30th with intermediate shredding 14th on the transport route 3 returned to the rotary drum again 4th to go through.

For the profitability of sewage sludge incineration, it is crucial whether the overdried sewage sludge is supplied with other sewage sludge in the optimal amount. the shows in the left, vertical column overdried sludge with various DR contents from 53% by weight to 83% by weight. The various overdried sludges have been assigned sludges with a low DR content of 19 to 28% by weight in a horizontal line. In between, mixing ratios of overdried sludge to sludge with a low DR content are listed, with which the overdried sludges listed in the left column can be mixed to a DR content of 52% by weight. The mixing ratios range from 0.77 to 35. That is, with a high DR content of 83% by weight, 0.77 times the amount of DR 83% by weight can be added to any amount of sludge with 28% by weight, until a mixture with a DR -Content of 52% by weight arises.
In the case of a sludge with TR 19% by weight and an overdried sludge of 53% by weight, every amount of sludge with TR 19% by weight must be mixed in with 35 times the sludge with TR53 until a mixture with a DR content of 52% by weight is obtained.
In the exemplary embodiment, the best economic results were achieved with an overdried sludge whose DR content was 60% by weight to 70% by weight and which was combined with a sewage sludge of 23 to 28% by weight. The resulting mixing ratio was 1.33 to 3.5. This result field is in the highlighted in gray.

In a second, not shown embodiment, instead of the twin screw conveyor 20th a double-axle ploughshare mixer from Lödige is planned.

In a third embodiment, not shown, the silo 6th not fed with the own sludge produced in the plant but with external sludge.

In a fourth exemplary embodiment, not shown, in addition to the supply from the system shown to the drying 2 and to the rotating drum 4th another supply, not shown, is also provided, which is obtained outside of the system shown.

In a fifth exemplary embodiment, not shown, the silos differ 5 and 6th supplied sewage sludge / own sludge. One sewage sludge is located under the glue phase, the other sewage sludge is located above the glue phase. From the silo 5 sewage sludge is drawn off via a ploughshare mixer and fed to the litter feeder 21 fed. The sewage sludge of the silo 6th however, it is withdrawn from another ploughshare mixer, not shown, and fed to another throw feeder. The other ploughshare mixer and the other throw feeder are located in the fifth embodiment, diametrically opposite the throw feeder 21 at the stove 7th .

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19531379 [0014]
• DE 19501736 [0014]
• DE 19512563 [0014]
• EP 883778 [0014]
• EP 526458 [0014]
• EP 3178577 [0014]
• DE 9208456 [0014]
• DE 4215530 [0014]
• DE 4138036 [0014]
• EP 2788701 [0014]
• DE 2401552 [0014]
• EP 1287304 [0014]
• EP 716264 [0014]
• EP 591299 [0014]
• EP 542958 [0014]
• EP 588152 [0014]

Claims (36)

Processing of sewage sludge for incineration in a furnace, preferably in a fluidized bed furnace, where dewatering takes place and the dewatered sewage sludge is then dried, where the drying is preferably a solar drying, with the most preferred solar drying also being provided with a heating that is independent of the weather , with which a desired drying can be maintained when the solar radiation subsides or a desired drying process is ensured independently of the solar radiation, whereby preferably, industrial use is made for the additional heating, whereby an enclosure is preferably provided for the solar drying, whereby still further preferably a transparent housing is provided, the sewage sludge preferably being spread out on the floor for drying and / or turned at intervals, characterized in that the solar drying is combined with floor heating is iniert and / or the solar drying is combined with an additional heating from above, is preferably combined with a supply of warm air and / or inert, warm heating medium and / or the sewage sludge is mixed with desiccant and / or the sewage sludge in an eligible mixture in The furnace is given up or several sewage sludge fractions that can be fed into the furnace are fed into the furnace and only then mix. Treatment of sewage sludge after Claim 1 , characterized in that warm air and / or inert warm gas is passed through the floor into the sewage sludge for floor heating. Treatment of sewage sludge after Claim 1 , characterized in that the bottom is provided with passage openings, preferably slot-shaped openings, for warm air and / or inert warm gas. Treatment of sewage sludge after Claim 1 , characterized in that the floor is provided with underfloor heating and is flowed through for use with warm, liquid heating medium, in particular with hot water. Processing after Claim 1 , characterized in that the additional heating from above is formed by at least one heating element, which is arranged above the sewage sludge in the housing and is flowed through by warm air or other heating means, in particular hot water, so the gases emerging from the sewage sludge as well as others from the Enclosed gases are indirectly heated and more moisture can be discharged with these gases. Processing after Claim 1 , characterized in that at least one desiccant from the following list of desiccants is preferably used as desiccant - ash - lime - overdried sewage sludge, the desiccants being added in such an amount until a sewage sludge in the glue phase is eligible for delivery. Processing after Claim 6 , characterized in that two sewage sludge streams are mixed with one another, of which one sewage sludge stream is located below the glue phase and the other sewage sludge stream is located above the glue phase and the mixing takes place before being fed into the furnace. Processing after Claim 6 , characterized in that two sewage sludge streams are mixed with one another, of which one sewage sludge stream is located below the glue phase and the other sewage sludge stream is located above the glue phase, and the mixing takes place after the task in the furnace. Processing after Claim 8 , characterized in that the two sewage sludge flows have different properties, in particular, in addition to the different moisture levels, have different density and / or different grain sizes. Processing after Claim 1 , characterized in that the mixing takes place in the furnace, preferably in a furnace designed as a fluidized bed with a stationary fluidized bed or in a furnace designed as a circulating fluidized bed. Processing after Claim 9 , characterized in that when several different sewage sludge streams are burned in the stationary fluidized bed above the fluidized bed, secondary air is applied for the combustion of particles there, which are carried beyond the fluidized bed, and an associated increase in the furnace temperature is counteracted by additional cooling. Processing after Claim 11 , characterized in that additional cooling is effected by injecting water. Preparation according to one of the Claims 8 until 12th , characterized in that a separate feed, preferably a separate throw feeder, is provided for the mixing in a fluidized bed furnace for each material flow belonging to the mixture. Processing after Claim 1 until 3 , characterized in that at least one throw feeder can be controlled. Processing after Claim 14 , characterized by the use of at least one throw feeder for the furnace, which can control -the number of sewage sludge throws per unit of time and / or -the direction of the sewage sludge throws horizontally and / or vertically and / or -the throwing distance and / or - the scattering of the sewage sludge so that the sewage sludge task can be optimized. Preparation according to one of the Claims 1 until 9 , characterized by the use of a paddle mixer or paddle mixer or ploughshare mixer for mixing the sewage sludge before it is fed into the furnace, the paddles and / or paddles and / or plowshares being attached to a shaft and rotating with the shaft in a housing and - have an inclination to the longitudinal direction of the shaft, so a mixture of the sewage sludge and at the same time a conveying effect on the sewage sludge is exerted in one direction of rotation of the shaft. Processing after Claim 16 , characterized by the use of a paddle mixer or paddle mixer or ploughshare mixer, the paddles and shovels or ploughshares of which are spaced in the longitudinal direction of the shaft so that there is space between the paddles and shovels and plowshares for fixed installations in the housing, with which the mixing effect is increased. Processing after Claim 17 , characterized by the use of paddle mixers and paddle mixers and ploughshare mixers with internals which have an additional cutting and mixing action and preferably in turn have the shape of paddles and / or shovels and / or plowshares. Preparation according to one of the Claims 11 until 13th , characterized by the use of a single-axis or double-axis paddle mixer or paddle mixer or ploughshare mixer, the double-axis paddle mixers or paddle mixers or ploughshare mixers preferably having paddles or paddles or plowshares that mesh with one another on the shafts and the internals are arranged outside the area of intermeshing parts. Preparation according to one of the Claims 16 until 19th , characterized by the use of housings with which the shafts and / or paddles and / or shovels and / or plowshares are surrounded, the housings having a dividing joint in the longitudinal direction, which facilitates assembly and disassembly. Preparation according to one of the Claims 16 until 20th , characterized by a screw conveyor between the paddle mixer or paddle mixer or ploughshare mixer on the one hand and the throw feeder on the other hand. Preparation according to one of the Claims 1 until 21 , characterized by a furnace operation coupled with the drying and mixing of the sewage sludge or a furnace operation independent of the drying and mixing of the sewage sludge. Preparation according to one of the Claims 1 until 22nd , characterized in that the heat of the waste gas from the combustion of the sewage sludge and / or waste heat from the furnace cooling and / or from the steam generation for a power generator is used for additional heating during the drying and / or mixing of the sewage sludge and / or transport of the sewage sludge will. Preparation according to one of the Claims 1 until 23 , characterized by a comminution of the sewage sludge and / or turning of the sewage sludge in the drying device and / or comminution of the sewage sludge on the conveying path from the drying device to the furnace charging. Preparation according to one of the Claims 1 until 24 , characterized by a storage / buffering of sewage sludge before charging the furnace. Processing after Claim 25 , characterized by the storage of different sewage sludges, one of which is overdried and the other is undried and both sewage sludges are brought together in a mixer before charging. System for carrying out the method according to one of the Claims 1 until 26th , whereby the system is composed of - a drying device, wherein the drying device a) is provided with a transparent housing that lets the sun's rays through and forms at least one rain protection, preferably also forms a separation from the ambient air b) wherein the housing has an air or gas outlet opening through which the im Housing accumulating air or gas can escape, whereby a filter is preferably located at the air or gas outlet opening, even more preferably the gas outlet opening or the filter is provided with a fan, the suction side of the fan facing the air or gas outlet opening -at least a mixer with a feed opening for dried sewage sludge and a feed opening for desiccant, preferably with a common feed opening for sewage sludge and desiccant - at least one conveying device for sewage sludge from the drying device to the mixer - at least one conveying device from the outlet of the Sewage sludge from the drying device for the return of sewage sludge to the inlet of the sewage sludge in the drying device - a switch in the conveying device from the drying to the mixer, to which the conveying device for the return of the sewage sludge is also connected - at least one moisture measuring device on the conveying path from the sewage sludge outlet the drying to the switch, wherein the moisture measuring device and the switch are connected to a common control device, so the switch is operated when a predetermined moisture content of the sewage sludge is exceeded. Plant after Claim 27 , characterized in that the drying device is provided with a heater for additional heating. Plant after Claim 28 , characterized in that the radiator consists of at least one closed pipe or hose through which heating medium flows. Plant after Claim 28 , characterized in that a split floor is provided in the drying device for floor heating. Plant according to one of the Claims 27 until 30th , characterized by a mixer designed as a drum screen for separating the sewage sludge with oversized grain. Plant after Claim 31 , characterized by a conveying device from the exit of the sewage sludge with oversized grain on the drum screen to the entry of the sewage sludge into the dryer for the return of sewage sludge with oversized grain. Plant according to one of the Claims 27 until 29 , characterized by a feeding device designed as a throw feeder, upstream of which a mixer designed as a paddle mixer or paddle mixer or ploughshare mixer is connected, Plant after Claim 30 , characterized in that the mixer is connected to at least two silos, wherein the silos can be opened individually or several at the same time for charging the furnace. Plant according to one of the Claims 27 until 31 , characterized in that the furnace is provided with at least two charging devices, each charging device being connected to a different sewage sludge silo. Plant according to one of the Claims 27 until 35 , characterized by heat exchangers in the flue gas flow of the furnace and / or in the exhaust gas flow of a turbine downstream of the furnace and / or in the cooling water flow of the furnace, the heat exchangers being connected on the heat output side to the heating of the drying device and / or to heating the mixer.

Images