SK3494A3 - Fueled granulation products made from liquid manure and the method of their manufacturing - Google Patents

Abstract

The invention concerns granular fuel made from liquid manure, in particular fuel for fluidized-bed furnaces, the fuel having the following composition: 0.86 to 45 % by wt. of dried liquid manure, 83.74 to 43 % by wt. of fluidized-bed coal dust, 5.4 to 2 % by wt. of quicklime and </= 10 to 48 % by wt. of residual water. The fuel has a round particle size of between 0 and 7 mm, a dust content of < 1 % and a free-running consistency, and is manufactured in a single operation in a mixer/granulator. The invention also concerns a method of manufacturing such granular fuels.

Description

FIELD OF THE INVENTION The invention relates to slurry fuel granules, in particular for fluidized bed combustion. It also relates in particular to a process for the preparation of these granulates.

The current steiv technique

The fuel granules from the blackening sewage sludge were known in the publication Granulat fur die V'erbrennung (combustion granules) Entsorga - Magazine - Entsorgungswirtschart, September 1990, pages 60 to 62. These fuel granules, consisting of mechanically dewatered cleaning sludge, in a mixer with forced mixing perfectly mixed with unspecified desiccants while practically granulating. The produced mixture is formed so that the dry matter is above the bonding stage, thus higher than about 50%, so that the mixture can be dried undisturbed in a special disk dryer. The product can be burned separately at most. in a fluidized bed furnace. The composition and properties of the dry granulates are not further refined. A disadvantage is that thermal drying is required to produce the granules, the non-combustible desiccant reduces the calorific value, and this is exacerbated by evaporation of the residual moisture.

From Klärschlamm in der Bundesrepublik Abwassertechnik, Vol. 2, 1990, pages 71 to 74, there are mentioned dispensable granules from sewage sludge to which are added additives to increase the dry matter, such as e.g. lime. The granule form is intended to improve the handling and shelf life and to minimize storage costs. Because the lime as conditioning and drying is:

. · ' »• i ^{{r l} L'agent used in large amounts, these granulates are less suitable for incineration due to reduced calorific value.

Recycling von Klärschlamm (Ulrich Loll, Berlin, EF-Verlag fur Energie- und Umwelttechnik GmbH, Vol. 2, 1989) is known for other methods of producing fuel granules.

In the Escher-Wyss sludge drying (section 5.1.2-, page 32, 33), the granules are dispensed into a fluidized bed dryer by means of a threaded dosing and turnstile, with the partial drying of the already dried material and in the dust separator, in the mixer and wet granulate. The drying is carried out thermally and the heat for drying is partly supplied directly by the vapor, partly indirectly by saturated steam or by oil heating of the fluidized bed dryer. The disadvantage is the high machine and energy demands for drying the granulate up to 98¾ dry matter.

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In dry sludge drying (section 5.1.6., Pages 39 to 41), the mechanically dewatered sludge is mixed with the already dried material, which is conveyed by a belt conveyor to the inner cylinder of the drum dryer, consisting of three coaxial rolls, and dried there with hot gas. entering at high speed (at 400-500 ° C) during the passage through these three cylinders. The granulate is separated from the produced granulate by changing 2-4 mm, which is discharged from the system. The rest of the material is ground in a mill and fed back into the system. This method also places great demands on machinery and energy consumption in the production of granules. Uraweltmagazine, May 1990, page 50, 51 discloses a process for the treatment of sewage sludge in which fresh sludge is treated by adding lime hydrate or carbide sludge and by adding organic flocculants and ferric chloride. This is followed by dewatering using a filter press. Instead of lime hydrate or carbide sludge, it is also possible to use electrofilter dust,

f * χ containing free unused calcium hydroxide. However, this process does not lead to the production of fuel granules. The use of elatroflitre dust is not advantageous for heavy metal contents, which necessitates special disposal measures.

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Similar problems encountered in the disposal of raw sewage sludge (thin sludge) are also associated with the disposal of slurry from the remaining 2 breeding stations.

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It is an essential object of the present invention to provide a process for producing fuel granules of the disadvantage of the known processes, which does not impose high demands on machinery and energy consumption and would result in a product particularly suitable for fluidized bed combustion.

design from slurry that should not be optimal in terms of

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SUMMARY OF THE INVENTION

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SUMMARY OF THE INVENTION The present invention relates to a process for the production of slurry fuel granules, in which slurry residues are mixed with lime and coal dust, the nature of which is that the slurry in the state in which it is obtained is mixed with coal dust and quicklime. the additives are adjusted so that the addition of burnt vague is determined on the basis of the sulfur content of the coal dust and the amount of slurry and coal dust is calculated according to the moisture content of these streams, to obtain wet fuel granules having a residual moisture content of less than 48% with round and free-flowing grains of up to 7 mm in size and long shelf life.

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The invention also relates to slurry fuel granules, in particular for fluidized bed combustion, which have the essence of having a dry matter of the following composition:

(a) 0,86 to 45% of the dry matter of manure;

(b) 83,74 to 43% by weight of coal dust; and

c) 5.4 to 2% quicklime, and o) rem a

d) have a residual moisture content of 10% by weight;

(e) have round grains of 0 to 7 mm in size, with a dust content of «1% and of a free-flowing consistency; and

(f) are produced in a single operation in a granulating mixer.

In a preferred embodiment, the invention relates to slurry fuel granules, in particular for fluidized bed combustion, characterized in that they have a dry matter of the following composition:

(a) 0,8 to 40% by weight of the dry matter of manure;

(b) 74,4 to 38% by weight of coal dust; and

(c) 4,8 to 2% quicklime, and in addition

(d) have a residual moisture content of <20% by weight;

(e) full grain size of 0 to 7 mm ·, a dust content of «1% and a free-flowing consistency; and

(f) are produced in a single operation in a granulating mixer.

In an even more preferred embodiment, the invention relates to slurry fuel granules, in particular for fluidized bed combustion, which consists in having a dry matter of the following composition:

(a) 0,4 to 23% of dry matter of manure,

(b) 74,4 to 38% by weight of coal dust; and

c) 4.8 to 2% by weight of quicklime and lime

(d) have a residual moisture content of <48% by weight;

(e) have a grain size between 0 and 7 mm, a dust content of podiel 1% and a high consistency; and

(f) they are produced in a single operation in a granulating mixer.

From the proposal, which represents a prior art state of the art) * (German patent application P 41 11 442.6), it is known to manufacture no. Fuel granules from raw sludge sludge. Surprisingly, it has been found that manageable fuel granules can be made from manure.

The fertilizer patent granules according to the invention are fuels which unexpectedly have excellent handling properties because they do not contain or release dust. Because of their good flowability, they are optimal for storage, transport and dosing. Their combustion does not burden the environment not only in terms of smoke diapers, but also solid waste. They have a calorific value that is comparable to dry brown coal.

The manure fuel granules according to the invention can be combusted in fluidized-bed furnaces without the addition of carriers or additional fuel, since they are well suited as a separate fuel for this type of combustion. Already wet fuel granules with a relatively high water content of up to 48% have a calorific value comparable to dried treatment sludge sludge. These wet fuel granules can thus be burned directly in the original sludge incineration plant without any changes in the kiln and heating system. After air drying, the dry fuel granules have a calorific value comparable to dry brown coal.

No expensive machinery and equipment are required to produce the fertilizer fuel granules of the invention. In addition to the usual pre-dewatering methods and equipment, only (jr. Mixer with inlet and outlet devices and equipment for interim storage of wet fuel granules and for circulating air drying without heat supply).

Depending on the dry matter content of the manure (diluted sludge), fuel granules can be produced by the appropriate addition of conditioning agents, both fine dry coal and lime. These self-combustible wet fuel granules are free-flowing and storable, therefore drying can take place. .from further energy supply. The purpose of this drying is to obtain a more dry, dry product.

It is advisable to situate the production of fuel granules at the place of manure. However, it can be placed in the center of a certain area dealing with the point of consumption of fuel combustion.

with animal production or granulates, i. j. in place

FIG. in the drawings

In FIG. 1, some preferred production options for self-combustible fuel granules are exemplified; slurry, including their conversion to more fuel-efficient fuel granules by simple drying with eye-air.

In FIG. 2 shows the course of temperatures in an incineration experiment with wet granulate.

In the junction unit, i. in the granulation mixer 1, damp fuel granules 12 are produced from the manure supplied from the manure container 2. The granulation mixer 1 is filled with manure inlet 11, coal dust inlet 9 and burnt lime inlet 10. The individual additives are metered in such a proportion that the wet fuel granulate at the outlet of the granulation mixer 1 has a mean humidity of 37 to 48%. The dosage of quicklime is controlled according to the sulfur content of the coal dust. The weight fractions of manure and lignite dust should be calculated by calculating the instantaneous moisture content of these material streams so that the resulting moisture of the wet fuel granules is 37 to 48%, since such granules can be handled by being non-sticky and non-greasy and also separately combustible. The granules thus obtained can be dried without the use of thermal drying energy by circulating air, for example in a circulating air silo 6, in a pneumatic dryer 7, or in a drum dryer 8, so as to produce more fuel fuel granules 13 having a moisture content of 20 to 10%; lower. If a waste heat source is available, the drying time may be shortened if necessary.

The fertilizer applied to the granulation mixer i may have 1.5 to 12% dry matter. The proportion of brown coal dust should be controlled according to the water content of the slurry so that the resulting wet fuel granules 12 have a moisture content of 37 to 48%.

Instead of brown coal dust, it is also possible to use coal dust or other carbonaceous dry materials, for example wood flour and the like, and these substances are dosed in appropriate proportions into the granulation mixer 1 to form self-combustible fuel granules 12. However, it is important the fuel granules 12 were sufficiently first and free-flowing to allow good handling, either in immediate use in combustion or in circulating air drying to obtain more fuel-efficient fuel granules 13.

Examples

The following are two examples of the production of manure fuel granules according to the invention. Another example describes a combustion experiment.

Example A

1.35 kg of manure, as obtained, with a dry matter of 6.5 is mixed in a granulating mixer with 2 kg of dry lignite (10% moisture) and about 7% quicklime (based on lignite) and the mixture is mixed. granulu je. The addition of flocculating additives or the like is not necessary. These self-combustible wet fuel granules have a moisture content of about 48% immediately after production and are free-flowing. Optionally, they can be used to produce more heat-dried granules, with a moisture content of about 20% after about 50 hours of air drying.

Example B

2.5 kg of manure, as obtained, with 10.25% dry matter (without the addition of flocculants) is mixed in a granulating mixer with 2.6 kg of brown coal (10% moisture) and about 7% quicklime ( based on lignite) and the mixture is processed to granulate. These self-combustible wet fuel granules have 48% moisture after production and are free-flowing. However, air-dried granules can be produced by heating them more heavily. ΙΌ 80 hours of drying, the humidity is reduced to 20% and after 100 hours to 14%.

Example C

Combustion tests with wet fuel granules from slurry '48% H ₂ 0),

Liquid fuel granules made of a mixture of slurry and lime-coal dust are introduced into a stationary fluidized bed combustion chamber with a thermal output of 300 kW as the only fuel. In these experiments, about 5 t of granulate were slept in continuous operation.

- heater heater

Fig. 2 shows an example of the course of temperatures over the course of the experiment versus time. The digits show the number of hours (h), in the fluidized bed 14 - fluid bed temperature, in the respective free space above it (15 - open air temperature) and before the cyclone (16 - cyclone temperature). During the start-up and heating phases a, which lasts from time D (burner start) to time g (burner off), the temperature in the fluidized bed and the free space rises approximately evenly. At the end of the heating phase and at point C, the fuel feed to the fluidized bed begins. After switching off the heater burner (instant B), stabilization phase b begins, which lasts until instant A, (which is defined by switching on the secondary air supply). Surprisingly, after the heater burner has been switched off, fluidized bed combustion is independently maintained by the addition of wet fuel granulates and stabilizes. The stabilization phase ends at time A (secondary air on) and. from this point until the end of the experiment (point 6), a very stable combustion phase c occurs, in which the temperature fluctuates very little. It can be clearly stated that the temperature course from time A when the secondary air dosing starts until the end of the experiment (time E) is uniform. Almost straight lines of the curves show that the dosing of wet fuel granules is very uniform. From this it can be deduced that the boring is intense and uniform.

Table 1 shows the results of elemental analysis and Table 2 shows other characteristics of wet granulates.

Table

Elemental analysis of wet fuel granules

Water total 47% dry matter 53% anhydrous

i.ah * (wf) pure horavav water. % ash% C% II% N% O%

WITH %

0.6

14.8

53.3

4.46

1.38 24 _f 5

0.99

14.9

53.6 4.49 1.39

24.6 1,0

63.0

5.28

1.63

28.9 * residual moisture product used for analysis —xjj

Table 2

Characteristics of granulates

Fuel granulate calorific value (wet) 10.2 MJ / kg (anhydrous) 21.4 MJ / kg

Bulk density 0.5 kg / kg ³ CaO content 2.44% by weight

Pr ;. Nearly constant temperature Fluidized bed combustion in the combustion phase c 720 to 740 ° C and correspondingly melt temperature in the open space 840 to 870 ° C gives rise to the emission values given in Table 3 when adding secondary air.

Table 3

Emission values

CO Ϊ NO _x i NO ₂ : 35 - 40 mg / m ³ 80 - 130 mg / m ³ 5 - · 15 mg / m ³ Analysis solid samples taken

It is clear from the technologically linked cyclone that a sufficiently high burn-out of wet fuel granules is achieved. The carbon content of the ash samples is in the range of 2.7 to 3.7% by weight.

Claims (3)

PATENT CLAIMS 1 granulating mixer A process for the production of slurry fuel granules 2, wherein the slurry 2 is mixed with lime and coal dust, characterized in that the slurry, as it is obtained, is mixed with coal dust and quicklime, wherein a plurality of individual additives shall be adjusted so that the addition of quicklime is determined on the basis of the sulfur content of the coal dust, and the amount of slurry and coal dust is calculated as a function of the moisture content of these streams. wet fuel granules having a residual moisture content of less than 48% with round and free-flowing grains of up to 7 mm in size and long shelf life were obtained. 2 magazine Jmojovice 6 silo with air circulation Pneumatic dryer 8 drum dryer 9 brown coal dust supply 10 supply of quicklime 11 manure feed 12 wet fuel granulate 13 dry fuel granulate 14 fluidized bed temperature 2. Manure fuel granules, in particular for fluidized bed sintering, characterized in that they have a dry weight of the following composition: (a) 0.86 to 4.5% by weight of slurry dry matter, (b) 133,74 to 43% by weight of coal dust; and (c) 5.4 to 2 tonnes of quicklime, and oltem thereof d) have a residual moisture content of í 10% by weight e.) have rounded grains between 0 and 7 mm in size, with a dust content of 1 1% and a free-flowing consistency; and (f) are produced in a single transfer operation in a granulating mixer. 3. Manure fuel granules 2, in particular for fluidized bed combustion, characterized in that they have a dry weight of the following composition: (a) 0,8 to 40% by weight of the dry matter of manure; (b) 74,4 to 3% by weight of coal dust; and (c) 4,8 to 2 fc of quicklime, and in addition (d) have a residual moisture content of <20% by weight; (e) have rounded grains of up to 7 mm in size, a dust content of 1 1% and a loose consistency; and (f) are produced in a single operation in a granulating mixer. 4. Slurry fuel granules, in particular for fluidized bed combustion, characterized in that they have a dry matter in the following composition: (a) 0,4 to 23% of dry matter of manure, (b) 74,4 to 33% by weight of coal dust; and c) 4.8 to 2 quicklime and in addition (d) have a residual moisture content of <48% by weight; (e) have round grains of 0 to 7 mm in size, with a dust content of «1% and of a free-flowing consistency; and f) they are produced in a single operation! in a granulating mixer. List of reference marks 3.5 temperature in the open air 16 temperature in cyclone A switching on the secondary air supply B switching off the heating; burner c switch on fuel supply D switch on heater burner E end of mix and start-up or heating phase b stabilization phase c stabilization combustion phase