DD266035B5 - Process for the production of activated coke from lignite - Google Patents

Description

Auiführungibeliplel

The invention will be explained in more detail with reference to four examples:

example 1

Xylitar miozfine raw lignite with the composition (d-base) ash 7 Ma .-%

Volatiles 51% by mass

Coke yield 49Ma .-%

fixed carbon 42% by mass

is pressed into moldings by the process according to the invention, this is coked under a purge gas atmosphere consisting of 10% by volume of CO ₂ and 15% by volume of H ₂ O ₀ according to the following regime: 3ObIs 30O ⁰ C 1.2 K / min

30ObIsIOOO ⁰ C 3 K / min

Time off: 2 hours

The thus treated moldings are cooled under inert gas and comminuted to a particle size of 5 to 8 mm. The granules were charged in the fixed bed with a SO ₂ -containing gas under the following conditions. Gas composition in vol.%: SO ₂ : 0.4; H ₂ O: 5; O _2: 5, N ₂ as a residual adsorption temperature: 183 ⁰ C Specific gas load (at 180 ° C): 730H ^'1 The abrasion resistance of Aktivkoksgranulates was in the ROGA drum determined (weighing 30g, 1000 revolutions, sieve cut 3 mm).

final temperature 640 725 800 850 1000 coking ( ⁰ C) Service life at 100% 4.7 5.2 4.8 3.9 0.1 Desulfurization (h) desulfurization 82 98 95 87 20 · ' nach6h (%) SOJ Beladungnach 5.5 6.2 5.8 5.3 0.9 x ' 6h (%) 95.3 94.4 94 95 95 Abrasion resistance (%) 230 240 255 260 270 Ignition point ( ⁰ C)

Example 2

Was tested the adsorption behavior of industrially produced BHT coke (Lauchhammer) and high-temperature coke (HT coke) from so-called, high-strength pyrolysis briquettes (gas combine black pump) to sulfur dioxide under the conditions acc. Example 1.

BHT coke HT Coke Service life at 100% Desulfurization (h) 0.1 0 desulfurization nach6h (%) 22 18 · ' SO ₂ loading according to 6h (%) 2.2 0.8 x ' Abrasion resistance (%) 90 95 Ignition point ( ⁰ C) 250 270 · After 2.6h

Example 3

Tar-rich, xylitic, Eocene lignite with the composition (d-base)

Ash 18.5% by mass

Volatiles 53.0 Ma ·%

Coke yield <J7.0Ma .-%

fixed carbon 28.5 Ma ·%

is pressed by the novel process with the addition of 4Ma .-% sulfite liquor having a solids content of 36Ma .-% as granulation to form moldings, these are gem. Example 1 coked and loaded with SO ₂ .

final temperature 600 700 7HO 800 850 coking ("C) Service life at 100% 0.3 0.9 4.3 4 4 Desulfurization (h) desulfurization 49 86 92 83 81 nach6h (%) SOJ Beladungnach 4.8 5.4 5.5 5.4 5.4 6h (%) 97.5 98 97 97 98 Abrasion resistance (%) 220 230 250 250 260 Ignition point ( ⁰ C)

Example 4

Industrially produced lignite low temperature coke (BTT coke) (Schwelerei Deuben) as well as an obtained by gas activation at 850 ° C activated (burnout 24Ma .-%) are loaded under the conditions of Example 1 with SO ₂ (particle size 1 to 2mm).

BTT coke activating life at 100%

Desulphurisation (h) 1,3 4,6

desulfurization

after 6h (%) 39 81

SO ₂ loading after 6h (%) 4.3 5.5

Claims (1)

A process for the production of activated coke from lignite for use as adsorbent, in particular for the desulfurization of flue gases, brown coal having a moisture content of 6-11 wt .-% and a particle size of less than 0.2 mm, optionally with the addition of a pressing aid with a pressure of 20-50MPa precompacted to formations, the shaped bodies then comminuted to a grain size of less than 3mm, the granulation obtained with a pressure of 140 to 250MPa pressed again to give moldings and these moldings at a heating rate in the range of 0.8-1.2K / min is for the temperature range of 50-350 ⁰ C and in the range of 2-5 K / min for the temperature range of 350-800 ⁰ C, be coked to a Verkokungsendtemperatur of 650-300 ⁰ C, characterized in that the Coking in a i0-30Vol .-% CO ₂ and 10-40Vol .-% water vapor-containing purge gas atmosphere is carried out at a stand-off time of 1-3 hours. The invention relates to a process for the production of activated coke from brown coal for use as adsorbent in gas purification, in particular for the desulfurization of flue gases. The activated coke produced according to the invention can be used in traveling layer adsorbers. Activated cokes are carbon adsorbents which, in comparison to conventional activated carbon, have only a low specific surface area (20 μmVg), but have high mechanical strength and a high absorption capacity for SO ₂ . The high mechanical strength (abrasion and compressive strength) is essential for economical operation of the Wanderschichtadsorber in flue gas desulfurization including the regeneration of the loaded adsorbent. There are already known processes for the production of such activated coke-mainly based on hard coal. A method is described in DE-OS 2624663, according to which adsorption cokes with an adjustable different pore system and high strength are obtained by shaping (one-part carbonaceous starting materials with plastics as binders, smoldering of the shaped articles and, if appropriate, activation.) Starting from a mixture of oxidized fat coal and butadiene-acrylonitrile copolymer, an activated coke which is suitable as an adsorbent in flue gas desulfurization It is also known to produce activated coke for SO ₂ adsorption from hard coal by sheathing an inactive core consisting of ceramic material with activated coke particles (WO In the patent document WO 85/04388 a method and the device for this purpose for the production of active form coke on the basis of pretreated hard coal is described. For dry flue gas desulphurization, conventional activated carbons of various types are also proposed (DE 3327727, DE 1 263970). A process for the production of activated coke from lignite with admixture of hard coal and soft pitch as binder is described in patents DE 1046818 and DE 1283807. Common to the known processes for activated coke production is the use of a binder by mixing this with the finely divided starting materials and moldings are produced, which are thermally treated. A disadvantage is the large number of necessary process steps that cause high operating costs and increase the cost of the product. According to DD-WP 252 550, a process for the production of carbon molecular sieves from lignite is known, in which the pore system can be adjusted solely by the selection of raw materials, the defined raw material preparation, the briquetting conditions and by a coking regime tailored to the raw material type. However, these carbon molecular sieves are of limited use for SO 2 adsorption because their specific surface area is too low. The aim of the invention is the technically and economically advantageous production of activated coke from brown coal for use for adsorptive gas purification, in particular for flue gas desulfurization. The invention has for its object to develop a process for the production of abrasion-resistant, granular activated carbon on Brdunkohlennasis that allows to realize a high specific surface area of the activated coke in a technologically simple manner with a defined pore system, without hard coal and binders are added have to. The technical problem is solved in that lignite with a moisture content of 6-11 wt .-% and with a particle size of less than 0.2 mm, optionally with the addition of a Preßhilfsmittels, eg in the form of sulfite waste liquor, with a pressure of 20-50MPe to Pre-compressed formations, the shaped body then comminuted to a grain size of less than 3 mm, the granulation obtained with a compression pressure of 140-250MPo pressed again to give moldings and these moldings with a heating rate in the range of 0.8-1.2 K / min for the Temperaturboreich of 50-350 ⁰ C and in the range of 2-5 K / min for the temperature range of 350-800 ⁰ C, are coked to a coking temperature of 650-800 ⁰ C, according to the invention, the coking in a 10 -30Vol .-% COjund 10-40Vol .-% water vapor-containing purge gas atmosphere is carried out at a Ausstehieit of 1-3 hours. Due to the nature of the raw material processing, the briquetting conditions and the coking regime, the poron size is deliberately adjusted. It is essential to the invention that the coking is carried out in a CO ₂ and water vapor-containing atmosphere and in the listed Tempeiaturbereich. This causes the pore walls to be freed of still adherent pyrolysis residues, surface oxides and chemisorbed gases, thereby substantially increasing the adsorption efficiency of the specific surface and improving the accessibility of the entire pore system without the carbon of the coke skeleton taking part in the reaction. This is achieved by, on the one hand, the treatment in the purge gas atmosphere is coupled directly with the coking and the treatment temperature remains limited. Under the given temperature conditions, the structure and the fitness of the activated coke are retained; So it does not come to Abbranderscheinungen on the carbon skeleton such. B. in activated carbon production by gas activation of BHT coke, with welchnr burns of over 40Ma .-% can be achieved.