DE4005782A1 - Removing acidic contaminants from coal - using additives as binders to produce self-fluxing cpds. - Google Patents

Abstract

An environment-friendly coal is produced for fluidised bed firing plants, using an additive in an extra hopper (until now it was mixed with additives) comprising high calorific value fuels as binders of SO2, HCl, HF and NOx. Pref. using the binders, e.g. fuller's earth, as adsorbents Ca-contg. materials, e.g. lime hydrate, fine lime, limestone are processed to self-fluxing burning mixts. by reducing nitrogen oxide ammonia-forming salts or similar cpds. ADVANTAGE - The additive mixt., which is self-fluxing, is added and consequently does not lead to a stress factor for coal burning to gas or oil but to a purposeful inexpensive relief.

Description

It is known for fluidized bed combustion combustion plants of coal or other fossil fuels Calcium in the form of calcareous rock and / or white fine lime is fed into the fluidized bed before the task or that the fluidized bed combustion these additives right next to the coal feed by means of a separate screw or other feeding device is added.

The disadvantage in many cases is that with a high sulfur content in the coal to maintain a certain Ca / S ratio much additive, e.g. B. limestone added must be depressed and thereby the calorific value considerably becomes.

The invention therefore proposes an additive mixture to admit that burns by itself and therefore does not a stress factor for those who are naturally competitive coal stands for gas or oil, but useful even leads to a cost relief.

This is inventively created in that high calorific binders such. B. bleaching earth, with additives for SO₂ incorporation of NO _x - z. B. additionally ammonia-containing salts - processed into a combustible mixture.

The economic impact is shown in the following calculation example shown:

With a coal with a calorific value of 7000 kcal / kg and one Sulfur content of 2%, at a required Ca / S ratio of 4 requires an amount of 20% CaCO₃.  

The calorific value of such a mixture then drops to 7000 / 1.2 = 5833 kcal / kg mixture.

With a limestone price of 35 DM / t 7 DM / t coal be used for the additive, which is an increase in Heat price around 1, -DM / Gcal means.

When processing the additive limestone with z. B. bleaching earth too a self-burning additive mixture stands up to the costs for limestone a relief through the use of waste disposal Residues compared. This results in a 1: 1 mixture of the two components is a level of limestone of 7, -DM / t coal, while for the bleaching earth part at one Bleaching earth price of 150 DM / t and 30 DM / t coal paid will. Taking into account the bleaching earth calorific value of The heat price change results in 4500 kcal / kg

When using white fine lime at a price of 90 DM / t with the same Ca / S ratio, an amount of 11.2% CaO - corresponding to 10.08 DM / t coal.

The associated heat price increase amounts to 1.44 DM / t coal the direct addition of additives.

In the case of the additive mixture of CaO with bleaching earth amounts to the heat price change

The higher the sulfur content, the cheaper this calculation and the lower the calorific value of the coal used is.  

The corresponding are at a sulfur content of 5% Numbers:

Limestone addition required 50%

Heat price change with direct additive +2.50 DM / t coal
Heat price change when adding the additive mixture -6.22 DM / t coal

or:

required white fine lime addition 28%

Heat price change with direct additive +3.60 DM / t coal
Heat price change when adding the additive mixture -2.03 DM / t coal

If the calorific value drops to z. B. Lignite heating value with 3500 kcal / kg, this is the case with CaO addition in the direct process

the heat price change
in the direct process DM 7.20 / t coal
and in the mixed process -3.33 DM / t coal

The mixing process brings relief to the coal, in particular also for German coal, which is practically against oil and gas must be represented economically.

Because the coal seller is now able to save fuel and additives also the simultaneous disposal of the residues to offer, as is done today by the Ruhrkohle Group Hölter-Fechner is already guaranteed to result from the Residues no competitive disadvantage.

The residue product can in turn be processed into one eluate-resistant building material for underground displacement, for which there is a Credit, similar to the previously known cement building materials and / or anhydride there.

Claims (2)

1. A process for the production of an environmentally friendly coal - preferably for fluidized bed combustion systems, characterized in that the coal is mixed in an extra silo - as previously with additives - the additives consisting, inter alia, of high-calorific fuel and this high-calorific fuel as a binder of SO₂, HCl, HF and NO _x binding additives. 2. The method according to claim 1, characterized in that the absorbent using high calorific binders such. B. bleaching earth, with Ca-containing substances such as lime hydrate, white lime, limestone and NO _x reduction serving ammonia-forming salts or similar compounds is processed to a self-burning mixture.