SE522179C2 - Preparation of granules comprising sludge and combustible material, using a rotating drum or plate with semispherical bowls on the inside - Google Patents

Abstract

The granule components are mixed using a rotating drum (1) or plate with inwards-facing semispherical bowls (2) on the inside. A method for preparing granules that contain one or more materials chosen from sludge, sawdust, peat, fibre resin, pitch, tallow oil, wax, paraffin, rapeseed oil, whey, paper pulp or lignin, is carried out using an continuously operating rotating drum or plate. The material is rotated around the inside of the drum or plate, which is provided with inwards-facing semispherical bowls with concave cavities.

Description

522 179 z Examples of materials include, but are not limited to, peat, wood shavings, lignocellulosic materials or wood lignin (obtained as a residual product after digestion or hydrolysis of lignocellulosic materials).

To increase the fuel value, whey, rapeseed oil, para fi in, resin and / or pine oil can be added. In order to obtain stronger granules, hardening oils such as tall oil or linseed oil can be added.

The granules must, in addition to sludge, contain components (raw materials) with different properties such as content of water and / or content of organic or inorganic material. At least one of these raw materials must have a dry matter content of more than 40% and preferably more than 50%. After mixing with such component, the common dry matter content should exceed 35% and preferably exceed 38%. This means that at e.g. a dry matter content of 60% of one heel (calculated as% by weight) of a two-component mixture, the other half may have as low a dry matter content as about 30% (such a mixture has a dry matter content of 40.0%).

Ingredients should preferably be reduced to manageable size. According to the invention, the size of individual particles should be reduced so that the maximum size can pass through a sieve with a hole diameter of 40 mm and preferably less than 30 mm. Particles that do not pass the sieve can be returned to a reduction machine (grinder). In most cases, however, the raw material is of such a nature that reduction to smaller particles is excessive.

In many cases it can be advantageous to first feed the raw materials to a mixing and homogenizing device. To achieve good results, a double-axis so-called paddle mixer, double-screw fi FROTAPULPERR brand or the mixing device described in U.S. Patent 4,908,10l. It is possible to add binders to these devices if desired. Suitable binders include lignosulfonate, linseed oil, tall oil, carbohydrates such as sugar, starch and whey. In some cases, a small amount of biofuel ash (max. 10% by weight) may be involved. The mixing and homogenizing device can in its simplest design consist of a cement mixer or simply of a rotating drum, which is provided on its inside with so-called bañlar, which usually consist of elongated iron rods which sit along or slightly obliquely in relation to the axis of the drum. The residence time can be regulated by changing the inclination of the drum in the axial direction. After thorough homogenization (mixing), the goods are fed to a granulation device. A granulating drum or a rotating plate can be used to granulate the mixture.

The core feature of the invention is to use a continuously operating drum 1 or plate 1 'whose transverse profile shows a number of inwardly facing bowls 2 (concave inside) integrated into a circle with irregular periphery in accordance with what is shown in fi g. Ioch 2. The design of the bowls means that the material to be granulated is brought to follow the bowls during the rotation. Through the hemispherical axis of the bowls, the granules are caused to rotate within each bowl.

When the bottom part of the drum is filled with granules, a certain grinding of the granules is obtained by the granules lying and rotating towards each other. Thanks to the unique design of the bowls, an efficient rounding of the granules is obtained.

The outer diameter 3 of the drum can vary from 200 mm up to 2000 mm. The length 4 can vary from 500 mm up to 20000 mm. The speed can be regulated within a fairly wide range. In principle, the speed should be changed in relation to the diameter of the drum. Thus, the speed can be increased with decreasing diameter and vice versa with increasing diameter. The drum can be driven by means of an electric motor or by means of a hydraulic motor (no drive device shown in fi g.).

The residence time in the drum can be varied by changing the inclination of the drum and / or by changing the speed. The inside of the drum can advantageously be coated with te fl on or ceramic to prevent deposits in the drum.

The drum can advantageously be supplemented with a sieve 5 which has the same transverse profile as the granulation drum. With the help of the sieve, the granules can be sorted by size. 522 179 3 Furthermore, in special cases the drum can be heated with a suitable heat source. In such a case, the drum can be surrounded by an insulated jacket.

Furthermore, the drum can be supplemented with nozzles for the application of an additional component, such as some type of a hydrophobic substance (pine oil, resin oil, wax or rapeseed oil).

With regard to granulation in a plate (fi g. 2) with a transverse profile according to the invention, essentially the same movement pattern and results are obtained as with granulation inside the thumb. To clarify the movement pattern during the granulation has in fi g. 2 drawn arrows. The larger arrow 8 indicates the direction of movement of the entire plate (which of course can also be the opposite). With the help of the smaller arrows 9 it is demonstrated how the blanks for granules and finished granules rotate within each individual bowl.

The granules which are produced can, in general, have the same dry matter content as the raw material had at the entrance to the granulating device. Through the handling, however, it may happen that the dry matter content increases by a few percentage points during the granulation.

Within the scope of the invention, the granules can be dried in connection with the granulation. The drying can advantageously be carried out with the help of flue gases, hot air or with superheated water vapor. In some cases it may be advantageous to resort to indirect drying via heating of the outside of the drum.

The granules must, after drying, have a TS content exceeding 60% and preferably at least 80%. During prolonged storage (> 20 days) and at> 20 ° C the TS content must be at least 85%.

The granules obtained should, according to the invention, have a substantially spherical shape. The diameter of the granules can vary within a wide range. Suitable diameter can range from about 1 mm up to 60 mm.

In special cases, after drying, it may be advantageous to finish producing granules in order to obtain better strength or to regulate their resistance to fi icing. Granules prepared according to the invention can be ground and used for powder firing.

Another mandatory area of use for the granules is the purification of air as described in e.g. U.S. Patent No. 9802821-0.

In the following, applications 1 of the invention will be demonstrated with the aid of Figures 1 and 2.

EXAMPLE 1 Biosludge from a treatment plant in Örnsköldsvik municipality and sawdust from Domsjö Sawmill were treated in a mixing and homogenization device 6. The weight share of dry-dried biosludge was 50% and the weight share of dry-dried sawdust was 50%. The dry matter content (TS content) of the bioslarm was measured at 29% and the TS content of the chips at 72%. After thorough mixing and homogenization, a TS content of 41% was obtained.

As a result of the described treatment, a separation of fmt shavings and coarser shavings was surprisingly obtained. Thus, the shavings were mixed with the sludge to form granules whose size varied from a few mm up to 45 mm. Even more surprising was that the smell from the sludge practically disappeared. In order to obtain a firmer size distribution and at the same time a further separation of the material from coarser particles in the chips, the material was passed on to the granulation drum 1 via the transport screw 7. By rotating the mixture in the specially designed drum, almost globular granules were obtained, 6-15 mm in diameter. . The result is particularly surprising given that the mixture fed to the granulation drum had a low TS content (41%). In addition to the good quality of the granules, a surprisingly efficient separation of the material was obtained from coarser particles, such as sticks with a length> 15 mm and a width> 3 mm. Thus, the granules contained at least 80% by weight of chips shorter than 15 mm and narrower than 3 mm. In order to separate coarser sticks from the granules fi ck the mixture pass the sieve 5 connected to the granulation drum. The mantle surface of the screen had slits whose width was 4 mm and length 50 mm. In the experiment, a very efficient separation of the wood sticks from the granules was obtained. 522 179 * IN EXAMPLE 2 The experiment was performed as in Example 1 but with the mixing of ground pulp (Modocrown ground to 26 ° SR) instead of mixing with sawdust.

The proportion of pulp with a TS content of 93.3% was 40% by weight and the proportion by weight of sludge was 60%. After thorough homogenization, samples were taken to determine the TS content, a value of exactly 40.0% was obtained. Granules of surprisingly high quality were also obtained during this test run.

Above all, a more even size distribution was obtained.

EXAMPLE 3 Biosludge from a treatment plant in Örnsköldsvik municipality and chips from Domsjö sawmill were treated in the mixing and homogenization device (6). In addition, fi berharts from Utansjö Mill was added.

The weight percentage of dry-dried biosludge was 30% and the weight percentage of dry-coated shavings was 50%, while the proportion of fi berharts was 20% by weight.

The dry matter content (TS content) of the biosludge was measured at 28% and the TS content of the chips at 86%. The fibrous resin had a TS content of only 21.5%. After thorough mixing and homogenization, samples were taken to determine the TS content and a value of 38.7% was obtained.

The mixture was fed by means of the screw conveyor (7) to the rotating drum (1) with properties which meet the conditions according to the invention and which are shown in fi g. 1.

By rotating the mixture in the specially designed drum, almost globular granules were obtained, the diameter of which was 4-15 mm. The result is particularly surprising given that the mixture fed to the granulation drum had a low TS content (38.7%).

EXAMPLE 4 A portion of the mixture of shavings, biosludge and berry resin obtained in the experiment described in Example 3 was passed to a partial dewatering press. Surprisingly, at a press pressure of 60 bar the TS content could be driven up to 53.2%. In previous attempts to press biosludge and fiber resin separately, only a marginal increase in the TS content (approx. 3%) of the biosludge was obtained, while no water could be squeezed out of the fi berh resin at all.

The thickened mixture was fed to the granulation drum (1). In the granulation, slightly smaller granules (3-10 mm) were obtained than in the experiment with non-thickened mixture.

EXAMPLE 5 Biosludge from a treatment plant in Ömsköldsvik municipality and a partially dried mixed heirloom with different degrees of humidification (according to von Post 3-8) were treated in the mixing and homogenization device. The proportion of dry-thinking biosludge was 50% by weight and the proportion of dry-dried peat was 50%. The dry matter content (TS content) of biosludge was measured at 29% and the TS content of peat at 78%. After thorough mixing and homogenization, a sample was taken for TS content and the value was obtained 42.4%.

The mixture of peat and sludge was conveyed by means of a screw conveyor (7) to the drum (1) with properties which meet the conditions according to the invention and which are shown in fi g. 1.

By rotating the mixture in the specially constructed timber, almost globular granules were obtained, the diameter of which was 3-10 mm. The result was particularly surprising given that the mixture fed to the granulation drum had a low TS content (42.4%).

EXAMPLE 6 Biosludge from a treatment plant in Örnsköldsvik municipality and whey in powder form were treated in the mixing and homogenization device (6). The proportion of dry-thinking whey was 50% by weight and the proportion by weight of biosludge was 50%. The dry matter content (TS content) of the bioslarm was measured to 29% and the whey TS content to 95%. After thorough mixing and homogenization, samples were taken to determine the TS content and a value of 44.4% was obtained.

The mixture of whey and sludge was fed by means of a screw conveyor (7) to the drum (1) with properties which meet the conditions according to the invention and which are shown in fi g. By rotating the mixture in the specially designed drum, almost globular granules were obtained, the diameter of which was 3-8 mm.

EXAMPLE 7 Biosludge from a treatment plant in Ömsköldsvik municipality and partially dried lignin were treated in the mixing and homogenization device (6). The proportion of dry-thinking biosludge was 50% by weight and the weight proportion of tonic-coated lignin was 50%. The dry matter content (TS content) of the bioslam was measured at 29% and the TS content of lignin at 86%. After thorough mixing and homogenization, samples were taken to determine the TS content and a value of 43.4% was obtained. The lignin was a by-product obtained by hydrolysis of wood. It can be mentioned that the cellulose is sugared and used for the production of ethanol.

The mixture of lignin and sludge was conveyed by means of a screw conveyor (7) to the drum (1) with properties which meet the conditions according to the invention and which are shown in fi g. 1.

By rotating the mixture in the specially designed drum, almost globular granules were obtained, the diameter of which was 3-8 mm. After drying, very solid granules were obtained with little tendency to dust.

EXAMPLE 8 The experiment described under Example 7 was repeated with the difference that the granulation was carried out in a rotating plate, fi g. 2. Granules of high and even quality were also obtained in this experiment.

The plate drive device and other peripherals were designed according to known technology. The only deviation was the outer frame of the plate which was arcuate (or wavy) according to fi g. 2.

EXAMPLE 9 Biosludge from a treatment plant in Ömsköldsvik municipality and chips from Domsjö sawmill were treated in the mixing and homgenisation device (6). In addition, tall oil from Husum's sulphate factory was added. The weight ratio of torite-coated biosludge was 30% and the weight ratio of dry-coated shavings was 50%, while the proportion of resin oil was 20% by weight.

The dry matter content (TS content) of the bioslear was measured to 28% and the TS content of the chips to 86%.

The TS content of tall oil was set at 100%. After thorough mixing and homogenization, samples were taken to determine the TS content and a value of 54.0% was obtained.

The mixture of shavings, sludge and tall oil was conveyed by means of the foam conveyor (7) to the drum (1) with properties which meet the conditions according to the invention, fi g. 1.

By the rotation of the mixture in the specially designed drum, almost globular granules were obtained, the diameter of which was 3-9 mm. After drying the granules, they became surprisingly hard and strong. Thus, the granules withstood strong throws against concrete floors.

The granules not only held. They even, like steel balls, bounced back from the floor.

Advantages According to the present invention, a number of advantages are achieved. Especially with regard to the fact that with the help of the specific granulation drum it is possible to produce granules of uniform size and high quality. It is particularly advantageous that granules of sludge taken directly from treatment plants can be produced in mixture with other materials. Although the sludge has a low TS content.

After drying, granules with high strength are obtained, which makes them storage-resistant and durable during transport and spreading. This also makes granules prepared according to the invention advantageous from a work environment point of view. Not least with regard to the fact that they emit a small amount of dust. In mixture with shavings and peat, the odor from the sludge is also eliminated.

Claims (7)

1 522 179 G CLAIM 1 Process for the production of sludge granules from municipal and industrial treatment plants and which granules contain one or more materials such as sawdust, peat, berry resin, resin oil, tall oil, wax, paraffin, rapeseed oil, whey, pulp or lignin . characterized in that the production of granules is carried out in a continuously operating rotating drum (1) or plate (1 '), the material being caused to rotate inside the inside of the drum or plate, which comprises inwardly facing semicircular bowls (2) which expose concave insides. Method according to claim 1, characterized in that the granules are forced to rotate inside the bowls for grinding and rounding. Method according to claims 1 and 2, characterized in that the granules are sorted by size in a sieve (5), which is directly connected to the drum. A method according to any one of claims 1 to 3, characterized in that the sludge contained has a dry matter content exceeding 15% and is mixed with at least one other material having a dry matter content of more than 40%. 5. Process according to any one of claims 1-4, characterized in that a hydrophobic substance such as tall oil, resin oil, wax or rapeseed oil is added to the granulation. Process according to any one of claims 1-5, characterized in that the granules are dried to a dry content exceeding 60%. Process according to one of Claims 1 to 5, characterized in that the granules are dried to a dry matter content of more than 85% before long-term storage.