HUT71546A - Granulated fuel made from liquid manure and a method of manufacturing of the fuel - 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 present invention relates to fuel granules made of manure, which are particularly useful in fluidized bed combustion plants. The invention also relates to a process for the preparation of such granules.

Fuel granules from clarifying sludge are known from Granulat für die Verbrennung, Entsorga-Magazine - Entsorgungswirtschaft, September 1990, pp. 60-62. page form. These fuel granules consist of mechanically pre-dewatered sludge, which is blended with a non-defined dry matter in a forced mixer and granulated. The resulting mixture has a solids content above the adhesive phase of about 50% solids and can thus be dried undisturbed in a special tray dryer. The product obtained can be burned without auxiliary fuel, for example in a fluidization furnace.

No details are given about the composition and properties of the dry granules. It is a disadvantage that the granules have to be heat-dried and the non-combustible dry matter reduces the calorific value and the partially dried granules reduce the calorific value by evaporation of the remaining water in the form of steam.

Klarschlamm in dér Bundesrepublik, Abwassertechnik, Book 2, 1990. 71-74. It is well known to have granules of clarifying sludge stored in a blend form, which are mixed with conditioners such as lime to increase the dry matter content. Granule shapes improve handling and shelf life and storage costs

- Can be reduced to 3 nominal. The use of lime as a conditioning or drying agent requires the use of larger quantities of lime, but the granules are less suitable for incineration due to their lower calorific value.

A further process for the preparation of fuel granules is known from Recyling von Klárschlamm (Ulrich Loll, Berlin, EFVerlag für Energie- und Umwelttechnik GmbH, Vol. 2, 1989).

In ESCHER-WYSS sludge drying (5.1.2, pages 32, 33), the sludge is granulated by addition of partially dried material and powder removed in the dryer in a mixer and fed into a fluidized bed dryer via a wet auger feeder and a sluice slide. The drying is carried out with thermal energy, which is carried out partly by direct steam condensation and partly by indirect injection of saturated steam or thermal oil into the runner dryer. The disadvantage of this process is the high mechanical and high energy consumption required to produce a 98% dry matter product.

In TCW sludge drying (5.1.6, pages 39-41), mechanically dewatered sludge is mixed with dried material, conveyed on a conveyor belt into an inner drum of a three-concentric drum and fed at high speed with hot gas flow (400-500 ° C). C) passed and dried through the three rollers. The granules obtained are removed from the dry matter by granules of 2 to 4 mm in size, the remainder being removed

- Crushed in 4 mills and fed back into the system. Again, this process requires a great deal of machine and energy to produce granules.

Umweltmagain, May 1990, pp. 50-51. A method for incinerating sewage sludge is disclosed on page 5, wherein fresh sludge is conditioned with lime hydrate or carbide sludge, and an organic coagulant and ferric chloride are added to the mixture. Further dewatering is carried out with chamber filter presses. Instead of lime hydrate or carbide sludge, electrofiltration powder can be used for conditioning, which contains free, unused calcium hydroxide. In the process, fuel granules are not produced. The disadvantage of using an electrofilter powder is that the heavy metals contained therein have to be disposed of separately! procedure.

There are similar problems with livestock manure removal of livestock manure (slurry) when removing manure.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the known processes and to produce or find in the manure fuel granules which are optimal in their composition and properties and which can be produced without high mechanical and energy consumption and particularly suitable for combustion in fluidization spaces.

The solution of the problem is fuel granules having the composition and properties as shown in Figures 1-3. claims

- 5 given.

A further embodiment of the fuel granules is described in subclaim 4.

The object of the present invention is achieved by the advantageous production of fuel granules having the characteristics set forth in claims 5 and 6.

It is known in the prior art (German Patent Application No. 41 11 442.6) to produce fuel granules from crude clarification sludges (dilute sludges). Surprisingly, it has been found that similar fuel granules can be produced from manure.

Surprisingly, the fertilizer fuel granules of the present invention form fuels which are excellent in handling because they contain little powder or produce little powder. Due to their round grain shape and fluidity, they are optimally stored, transported and dispensed. Their incineration is relatively environmentally friendly in terms of both the flue gases generated and the solids remaining. They have a high calorific value, which is comparable to lignite calorific value.

The fertilizer fuel granules of the present invention can be used in fluidized bed combustion plants without any additional carrier or combustion auxiliary, since they burn well without auxiliary fuel in such a combustion system. Even the relatively high wet fuel granules with a water content of up to 48% can be compared to the dried fuel value.

- 6 calorific sludge calorific value. The wet fuel granules can be directly incinerated in the sludge incinerator without the need to change the system in the furnace or waste heat system. When dried in air as dry granules, their calorific value is comparable to that of lignite.

The manufacture of the fuel granules of the invention according to the fertilizer does not require expensive special equipment or machinery. In addition to the usual pre-dewatering process and equipment, only one granulator, mixer, and intermediate storage prior to drying of wet fuel granules in ambient air or by thermal energy transfer are required.

Depending on the dry matter content of the manure (slurry sludge), wet granules can be prepared by adding suitable conditioning agents such as finely divided dry carbon or lime. The resulting wet fuel granules, which burn with no other fuel, are free-flowing and well-stored, so that they can be easily dried in ambient air without additional energy consumption, and thus produce high-calorie dry fuel granules.

Fuel granules are conveniently prepared at the site where they are formed. It is conceivable to produce granules at a central location, such as at a central location in the vicinity of smaller livestock farms, or at a location where fuel pellets are burned.

Figure 1 illustrates, by way of example, a preferred way of producing manure-fueled pellets that can be burned without other fuels and further converts the resulting pellets into higher calorie dry fuel pellets by simple air-drying.

Figure 2 shows the temperature flow of a combustion experiment with wet fuel granules.

In the granulation unit, i.e. the granulator mixer 1, the wet fuel granules 12 are prepared from the manure stored in the manure tank 2. Starting materials are introduced into the granulator 1 via the manure feeder 11, the brown coal powder feeder 9 and the burned lime feeder 10 in an amount such that the average moisture content of the wet fuel granules 12 produced in the granulator 1 is between 37 and 48%.

The burnt tale 10 is added based on the sulfur content of the brown coal powder 9. The amount of fertilizer 11 and brown coal powder 9 depends on the moisture content of these materials, taking into account the production of wet fuel granules between 37 and 48% moisture content. Wet fuel granules having such moisture content have sufficient strength and flowability (non-stick and non-lubricating) and can be burned without any other fuel. Optionally, they can also be used without thermal drying, only after drying in ambient air, for example in the air slide 6, the washer dryer 7 or the drum 8, while the 13 are converted into higher energy dry fuel granules 8 with a moisture content of 20 and 10. % or less. If waste heat is available, this may shorten the drying time.

The dry matter content of the fertilizer 11 introduced into the granulating mixer 1 may be between 1.5 and 12%. The amount of brown coal powder depends on the water content of the manure and is such that the moisture content of the 12 wet fuel granules produced is between 37 and 48%.

Instead of lignite powder 9, coal powder or other carbonaceous solids, such as wood flour, may be introduced into the granulating mixer 1 in sufficient quantities to produce wet fuel granules which can be burned without the use of other fuels. It is important that the wet fuel pellets 12 produced have sufficient strength and flowability to be well handled and directly usable as fuel without any other fuel, or optionally to produce fuel pellets 13 from ambient air.

The following two examples illustrate the preparation of the fuel granules of the present invention from manure, and another example illustrates the combustion experiment.

The example

1.85 kg of original pig manure with a dry solids content of 6.5% is mixed with 2 kg of dry lignite (10% moisture) and about 7% calcined lime (based on lignite) and processed into granules. The use of a coagulating agent or the like is not ·····································•

- 9 required. The resulting wet fuel granules, which can be combusted without any other fuel, have a moisture content of about 48% immediately after production and are flowable. The resulting granules may optionally be made into high calorie dry fuel granules using air drying for about 80 hours, resulting in a final moisture content of 20%.

Example B

2.5 kg of original bovine litter with a dry matter content of 10.2% (without coagulant), 2.6 kg of dry brown coal (10% moisture content) and about 7% of calcined lime (based on the proportion of lignite) are granulated and processed into granules. The resulting auxiliary fuel combustible wet fuel granules, once prepared, have a moisture content of 48% and are flowable. Optionally, the resulting granules can be converted into higher energy dry fuel granules using 80 hours air drying to 20% humidity and 100 hours drying to 14% moisture.

Example C

Burning experiment with wet fuel granules from manure (48% H ₂ O)

Wet fuel granules made from manure and brown coal powder are fed as a single fuel into a stationary fluidization chamber with a thermal output of 300 kW. In the experiment, about 5 tons of granules were burned continuously.

• ··· * ·· · '· · · «· * ·

Figure 2 shows the temperature change over time during the experiment, the digits represent the number of hours (h) in the fluidizing layer (14 fluidized bed temperature), the free space placed above it (15 free space temperature), and the before cyclone (16 cyclone temperature). During the start-up phase and the heating phase, which extends from time D, from the start of the heating reactor to time B to the shutdown of the heating reactor, the temperature in the fluidized bed and in the open space increases almost equally. Towards the end of the heating phase A, the injection of fuel into the fluidized bed begins at time C. After switching off the heating reactor (time B), stabilization phase b starts, which lasts until time A (secondary air supply). After switching off the heating reactor, the combustion process in the fluidized bed only occurs through the addition of wet fuel granules, without other auxiliary fuel, and is stabilized by time A (secondary air supply on) and from the end of the experiment (time E) a very stable c occurs in which only a very small decrease in temperature is observed. It is clear that the temperature change is constant from time A (at which the secondary air supply starts) to the end of experiment E. The near-straight curve gradients mean that the dosing of the wet fuel granules is also uniform. It can also be seen that the combustion process is intensive and even.

In the following Table 1, elemental analysis of the wet fuel granules used, in Table 2 more

Λ ·

- 11 • ··· ··· • · · ♦ ·· · «« · ««.

Table 1

Elemental Analysis of Wet Fuel Granules

Total Water%

Residual dry matter 53%

i.an. * wf. waf Water % 0.6 - - Ash % 14.8 14.9 - C % 53.3 53.6 63.0 H % 4.46 4.49 5.28 N % 1.38 1.39 1.63 0 % 24.5 24.6 28.9 S % 0.99 1.0 -

*) Analytical moisture

Table 2

Characteristics of granules

The calorific value of fuel granules (wet) 10.2 MJ / kg (Wf) 21.4 MJ / kg shaking Weight 0.5 kg / dm ³ CaO content 2.44% by weight

• · * · ··· ♦ • · · · · · · ««

By maintaining a near constant temperature of 720 to 740 ° C during the fluidized bed combustion in the firing phase c and a corresponding free space temperature of 84,870 ° C, the emission values given in Table 3 are obtained during the secondary air addition.

Table 3

Emission values

CO : 35-40 mg / m ³ NO _X : 80-130 mg / m ³ N02 : 5-15 mg / m ³

Solid state samples from the post-cyclone cyclone show that proper combustion of the wet fuel granules can be ensured. The carbon content of the ash test is between C = 2.7% and 3.7% by weight.

• ♦ ·· • ·

- 13 ~

Reference List Granulation Mixer Fertilizer Container Ambient Air Tank Wash Tower Dryer Drying Carbon Brown Powder Feed Burnt Lime Feeding Fertilizer Feeding Wet Fuel Granule Dry Fuel Granule Fluidized Bed Temperature Free Space Temperature Cyclone Temperature Secondary Air Dosing Startup Furnace Furnace Upfill firing phase

Claims (3)

1. Fuel granules of manure, in particular for fluidised bed combustion plants, wherein the composition of the fuel granules, expressed as dry matter, is as follows: (a) between 0,86% and 45% by weight of dry matter, b) 83.74 to 43% by weight of carbon powder, (w.f.) (c) 5.4 to 2% by weight of calcined lime, characterized in that: (d) the granules contain <10% w / w residual water; and (e) they are round in grain and have a particle size of between 0 and 7 mm and a content of <1% in powder form, and have a flowable consistency; f) can be prepared in a process step in a granulating mixer. 2. Fuel granules of manure, in particular for fluidised bed combustion plants, wherein the composition of the fuel granules, expressed as dry matter, is as follows: the) 0.8 - 40 crowd% manure solids, b) 74.4 - 38 crowd% coal dust, (w.f.) c) 4.8 - 2 crowd% burnt lime, characterized in that (d) the granules contain <20% water by weight; and (e) they are round in grain and have a particle size of between 0 and 7 mm and a content of <1% in the form of a powder, and have a flowable consistency; · · «(F) can be produced in a process step in a granulating mixer. 3. Fuel granules of manure, in particular for fluidized bed combustion plants, wherein the composition of the fuel granules, expressed as dry matter, is as follows: (a) 0,4 to 23% by weight of dry matter, b) 74.4 to 38% by weight of carbon powder, (w.f.) c) 4.8 to 2% by weight of burnt lime, characterized in that: d) the granules contain <48% by weight of residual water; and (e) they are round in grain and have a particle size of between 0 and 7 mm and a content of <1% in powder form, and have a flowable consistency; f) can be prepared in a process step in a granulating mixer.