DE19608386C2 - Process for the production of solid and porous lignite fuels with improved combustion properties - Google Patents

Description

It is known to use lignite directly or in processed form, especially as a briquette different sizes to use in incinerators. Lignite briquettes are made from dried lignite by high pressure compression preferably produced with form channel stamp presses (extrusion presses). For this, the processed lignite dried to moisture content by 18% and with high press pressing from p ≈ 70 to 120 MPa so compacted that the strength-forming binding forces te and binding mechanisms between the solid particles are triggered. There briquettes with high strength and density as well as low porosity are created. Lignite briquettes are characterized by their high fire resistance. You who which are usually fed in batches for combustion (combustion). A long ignition and burning period is characteristic of the combustion cycle de, is an uneven burn over the cross section of the combustion chamber or Fuel fill and is a sequential combustion of the various ingredients of lignite.

The associated temporal fluctuations in the rate of combustion, the quantity of heat released, the oxygen requirement, and the resultant The amount of flue gas and the flue gas composition inevitably lead to especially in small fireplaces, to increased emissions in the ignition and burning phase.

It is also known that briquettes with a high content of lignite containing xylitol Density and strength can be generated, with the xylitol especially the briquette bonded by form-fitting bonds. On the other hand, the xylites diminish in this dense bandage the briquettes are thermally resistant due to faster ther mix disintegration and by the appearance of stress cracks in the heating phase. These adverse effects are caused in particular by the fact that the xylitol particles vary greatly in size and grain shape and are only heterogeneously distributed in the Briquette association are involved.

According to DE-PS 2 33 148 and DE-PS 4 19 811, the addition of wood is also known flour to moist brown coal or the separation of brown coal in different Fractions to be treated before briquetting.

The object of the invention is to produce lignite fuels by means of a method places that lead to low emissions during combustion, a good ignition and Have burning behavior that has a high thermal or fire resistance and that is easy to use, advantageous in packaging and dispensable for Use in automated fireplaces.

The object is achieved with the inventive features of claims 1 and 2.

The advantages achieved with the invention are in particular that the brown carbon fuels

• - are well suited for a largely dust-free filling in bags, sacks or Container,
• - can be dosed easily and evenly into the combustion chamber,
• - Evenly, especially from above and over the entire firebox the,
• - A high level of fire resistance right up to the final phase of the combustion process with even and controllable combustion in the combustion chamber,
• - a high level due to this even, complete and complete burnout and enable fast effective heat utilization and comparatively little Emit pollutants.

The procedure is described in more detail below:
The xylitol-containing lignite is first split into fiber xylitol and the remaining coal base. The solid natural adhesions between the xylitol and the lignite matrix are separated by crushing with a high energy input and subsequent screening.

After separation, both raw material groups are separated into one good specific fineness prepared. The brown coal base mass is on a grain crushed from 0-5 mm. The separated xylitol, on the other hand, must be used with suitable mills be shredded to lengths <15 mm. Then there is an intensive ver Mix the shredded xylite with the prepared brown coal base. The mixing process should be designed so that the fine xylitol fibers are very homogeneous and be mixed evenly into the lignite base mass. The mixing process has with the addition of water or aqueous solutions or dispersions. The liquid stabilizes the mix through adhesive bonds and mobilizes the binding  assets of brown coal and xylitol fiber. A material system consisting of xylitol and Lignite with new properties.

The mixture ratio of lignite matrix and xylitol can be used in a wide range Chen be varied. The metered amount of liquid must be dimensioned optimally be that a partially surface-moist and homogeneous mix is created. The An part of the liquid is strongly dependent on the properties of lignite and xylite dependent and is mostly 10 to 20% based on the mass of brown coal and xylitol.

The plastic mix is subsequently made into compacts with low pressure preferably small piece size, e.g. B. d = 2 mm to d = 30 mm shaped.

The compacts are then dried to a moisture content of w 22%. in the As a result of drying, compacts with high strength and high porosity are created of about 20-40%.

This new way of producing brown coal fuels by metered vermi research, moisture agglomeration and subsequent drying lead to new and ver improved handling and combustion properties.

As a result of the high porosity and the homogeneous mixture of substances, the press burns succeed quickly, evenly and completely and can be used especially for small for dosed into the combustion.

In contrast to the conventional combustion of lignite briquettes and others Large-scale fuels cause the new fuel properties that the individual combustion phases merge into one another and thus to a clear one Reduce pollutant emissions during combustion.

The time fluctuations in the combustion process are significantly reduced. The burning phase in particular is reduced compared to the lignite briquette by a multiple. Air supply, fuel use and heat use can be better be coordinated.

With the new fuel, rapid heat availability after the start burn the compacts and an even or needs-based heat supply and low-pollutant combustion with high efficiency. The Compacts according to the invention are therefore particularly suitable for incineration plants with automatic loading.

Claims (3)

1. A process for the production of solid and porous non-conventionally bri-chained lignite fuels with improved combustion properties, characterized in that

• a) raw xylitol-containing lignite is split into fiber xylitol and lignite matrix in a mechanical processing process,
• b) Both the fiber xylitol and the lignite base mass are subjected separately to a further, material-adapted comminution and classification to a well-specific precision, the carbon base mass being processed to a grain size of 0-5 mm and the separated xylitol being pulverized and broken down to lengths <15 mm is crushed,
• c) the separately prepared substances, fiber xylitol and lignite matrix, are combined by intensive mixing with the simultaneous addition of water, aqueous solutions or dispersions to form a coal mixture, with the minimum proportion of processed xylitol 10% and the proportion of the liquid 10-20% based on the coal mix is
• d) the coal mixture is shaped or agglomerated under low pressure,
• e) the shaped or pressed agglomerate is dried.

2. A process for the production of solid and porous lignite fuels not briquetted in a conventional manner with improved combustion properties, characterized in that

• a) raw lignite is used as the lignite base mass and fibrous materials not derived from the lignite,
• b) both the fibrous materials and the lignite base mass continue to be subjected to a material-specific comminution and classification separately to a well-specific fineness, the carbon base mass being prepared to a grain size of 0-5 mm and the fibrous materials being broken down and comminuted to lengths <15 mm,
• c) the separately prepared substances are metered into mixed material by intensive mixing with the simultaneous addition of water, aqueous solutions or dispersions, the minimum proportion of prepared fibrous materials being 10% and the proportion of the liquid being 10 to 20% based on the mixed material,
• d) the mix is shaped or agglomerated under low pressure,
• e) the shaped or pressed agglomerate is dried.

3. The method according to claim 1 or 2, characterized in that the method steps c) and d) be carried out sequentially or simultaneously.