DE2853370A1 - Prodn. of coke with reduced sulphur content - by hydrogenation gasification of coal in a fluidised bed - Google Patents

Abstract

Brown coal contg. sulphur is converted to coke by 45-70 (45-65)% gasification with H2 (at least partly in counter-current flow) in a fluidised bed under 60-125 (70-125) bar at 800-950 (850-950) degrees C with dwell time 10-30 (10-25) mins. at H2 content in the exit gas of >=25 vol.%. Up to 90% of S is removed, c.f. up to 45% by usual hydrogenating gasification of brown coal, with a corresp. reduction in SO2 emission or combustion of around 90%.

Description

Process for obtaining a coke with reduced proportions

in the amount of sulfur introduced with the coal in the hydrogenating Gasification of coal.

The invention relates to a method for obtaining a coke with reduced proportions of the amount of sulfur introduced with the coal in the hydrogenating process Gasification of brown coal. Such a coke comes in the interests of environmental protection Efforts against the sulfur content in the hydrogenating gasification of coal to reduce the coke by removing as much sulfur as possible with the raw gas and a coke is obtained which, when burned, causes SO 2 emission to a large extent is avoided.

During the hydrogenation gasification carried out in the usual way a sulfur breakdown in the gasifier of up to about 80% is achieved by hard coal in the hydrogenative gasification of lignite, the proportion of that brought in with the coal Sulfur that is discharged from the gasifier with the raw gas is undesirably low. It is generally up to about 45 t.

There are methods of reducing the sulfur content of solids Fuels known. DE-OS 26 59 725 discloses a method in which Coal first crushed to a grain size of less than 0.1 mm and then with heating speeds on the order of more than 20,000 C / min. to a reaction temperature of 0 brought from 700 to 1,100 C and 1 to 6 seconds at a pressure of 1 to 15 bar is left until the coal dust and gas are separated. In doing so, if necessary a partial gasification of the coal carried out in order to take advantage of the well-known fact that part of the sulfur can be removed with the gas in the form of H2S. It will However, it is expressly pointed out that the H2S content in the gas is not higher than 0.3 vol.% Should be. The process is particular because of the fine grinding required the coal and its very rapid heating is complicated and expensive.

Furthermore, DE-PS 25 16 467 describes a process for desulfurization known of finely divided sulfur-containing carbon-containing materials, in which these in a hydrogen-containing carrier gas stream through a desulfurization zone be guided in countercurrent with a stream of metal oxide pellets. The resulting Hydrogen sulphide reacts with the metal oxide to form metal sulphide, which is produced from the Reactor is removed and regenerated oxidatively. This process is also time-consuming and cumbersome, especially because of the recycling of the metal oxide.

In a method for desulfurization known from DE-OS 25 18 110 of coke, this is used to convert and remove the inorganic in it Sulfur compounds e.g. B.

washed with hydrochloric acid before the coke thus treated with a hydrogen-containing one Gas is treated to remove organic sulfur compounds. Here too it applies that the procedure is cumbersome and expensive.

The invention is based on the object of the hydrogenating Gasification of lignite so that a coke with such a low sulfur content is generated that when it is burned practically none or at most only one low S02 emission occurs.

To solve this problem, the invention proposes that the hydrogenating Gasification of lignite in the fluidized bed at 60 to 125, preferably 70 to 125 bar, and 800 to 9500 C, preferably 850 to 9500 C, at least partially im Counterflow of coal and hydrogen with a carbon gasification degree of 45 to 70%, preferably 45 to 65%, and under such a hydrogen partial pressure carries out that the raw gas leaving the gasifier has a hydrogen content of at least 25 vol.

with the dwell time of the coke in the gasifier at 10 to 30 minutes, preferably 10 to 25 minutes.

One produced when the conditions according to the invention are complied with Accordingly, coke exhibits a high level of H2S removal with the raw gas 2 a reduced amount of sulfur introduced with the coal. Come in addition, that during the combustion of the coke produced according to the invention, the SO2 emissions is much less than the sulfur content of the coke corresponds. It will up to 90% of the sulfur contained in the coke is not emitted as SO2, so that only very small proportions of the sulfur contained in the coal In the form of SO 2.

This results in the possibility of giving the coke a predetermined Mix in amount of another fuel containing more sulfur without due to the low S02 emission of the coke, the total S02 emission of the fuel mixture exceeds the permitted values.

The advantages of the gasification according to the invention occur in particular when Use of lignite, e.g. B. of the type found in the Rhineland or in Australia is won. The lignite is made in the usual way by drying and grinding prepared.

Water contents of around 5 - 20% can be set.

The grain size of the lignite will be in the range of 0-4 mm Select. It must only be ensured that the fluidized bed can be built up undisturbed. If necessary, the coal used can be preheated and smoldered.

The fluidized bed is made with the help of the gasification means, if necessary also circulated raw gas, operated in the usual way.

There should be sufficient space above the fluidized bed for post-reaction be arranged. Several fluidized beds can be arranged one above the other. According to the invention it is necessary that at least part of the gasification in countercurrent of coal and gasifying agent is carried out. Generally this will be in the lower section of the fluidized bed happen when the countercurrent is not maintained over the whole bed will. The height of the fluidized bed is chosen in the usual way.

According to the invention, only medium temperatures should be used, d. H. within the stated temperature range of approx. 800-9500 C, in particular from 850-9500 C. The reaction pressure should be in the range from approx. 60-125 bar, in particular 70 -125 bar.

In addition to hydrogen, mixtures of hydrogen can be used as gasification agents can be used with steam or carbon dioxide.

The hydrogen required for the hydrogenation reactions should be one Have a minimum concentration of about 60%. Levels of carbon monoxide, methane or Nitrogen disturbances do not. If necessary, a part of the raw gas produced can dem Gasifying agents can be added. The proportion of hydrogen must always be like this be chosen so that its content in the raw gas is at least 25 volts 8. The gasification agents are heated in the usual way before introduction into the reactor, for. B. to 6500 C.

Compliance with the residence times mentioned is of particular importance of the coke in the reactor of about 10-30 minutes, especially short times from about 10 - 25 minutes. It is obvious to the expert that the operating parameters are coordinated within the ranges specified for them must be what is possible without difficulty.

The following examples show the effect and advantage of the invention.

In all cases it is the hydrogenating gasification of Rheinischer Brown coal.

Example 1 Operating parameters elemental analysis (%) rhein. Coke coke Coke residence time: 18 min, N 0.72 0.20, fluidized bed temperature: 8800 C Sges 0.28 0.31 Carburetor pressure: 80 bar 0 24.80 3.49 Degree of coal gasification: 67.5% C 65.40 85.00 Degree of gasification: 57.4% H 5.10 1.20 Degree of desulphurization: 64% ash 3.70 9.80 100.00 100.00 SO 2 emission of the coke during combustion: theoretically 0.220 kg S02 / GJ effectively 0.019 "" " example 2 operating parameters elemental analysis (%) rhein.

Lignite coke coke residence time: 24 min. N 0.70 0.22 fluidized bed temperature: 8500 C Sges 0.34 0.38 total Carburetor pressure: 95 bar 0 22.93 3.11 Degree of coal gasification: 70.0% C 66.20 80.56 C degree of gasification: 63.6% H 5.33 1.31 Degree of desulphurisation: 66.3 % Ash 4.50 14.42 100.00 100.00 Example 3 Coke residence time: 33 min. N 0.7 0.2 Fluidized bed temperature: 8500 C 5ges 0.28 0.55 Carburetor pressure: 80 bar 0 24.8 2.5 Degree of coal gasification: 72.2 % C 65.4 82.9 C degree of gasification: 64.4% H 5.1 1.1 Degree of desulphurisation: 45% ash 3.72 12.75 100.00 100.00 SO2 emissions from coke during combustion: theoretical 0.380 kg S02 / GJ effective 0.092 "" " Example 4 operating parameters Elemental analysis (%) rhine.

Lignite coke coke residence time: 30 min. N 0.7 0.2 fluidized bed O temperature: 900 C 5 0.26 0.50 total carburetor pressure: 95 bar 0 23.8 1.6 Degree of coal gasification: 77.4% C 66.8 81.3 C degree of gasification: 72.5% H 4.9 0.8 Degree of desulphurisation: 56% Ash 3.54 15.60 100.00 100.00 Example 5 Coke residence time: 35 min. N 0.70 0.15 Fluidized bed temperature: 9100 C 5ges 0.45 1.24 carburetor pressure; 65 bar 0 24.11 0.91 Degree of coal gasification: 72.6 % C 65.24 81.90 C gasification fraction: 66.1% H 4.80 0.80 Degree of desulphurisation: 24.5% Ash 4.70 15.00 100.00 100.00 Example 6 Operating parameters elemental analysis (%) rhine.

Lignite coke coke residence time: 43 min. N 0.70 0.15 fluidized bed temperature: 9000 C 5 0.45 1.40 total carburetor pressure: 65 bar 0 24.11 0.90 coal gasification degree: 75 % C 65.24 77.90 C degree of gasification: 70.0% H 4.80 0.90 Degree of desulphurisation: 22% ash 4.70 18.75 100.00 100.00 The above examples clearly leave that Occurrence of the desired effect when applying the teaching according to the invention recognize.

In Examples 1 and 2, all operating parameters are within of the specified ranges with the result of high sulfur degradation.

In Examples 3 and 4, there is one operating parameter in each case Edge or outside the specified areas with the result of a significantly lower Degree of desulphurization.

In Examples 5 and 6, one operating parameter is outside each case of the specified range. Here the degree of desulphurisation is noticeably lower than in the case of Examples 3 and 4.

Claims (1)

Claim method for the production of a coke with reduced Proportions of the amount of sulfur introduced with the coal and during the combustion of the Coke's reduced sulfur dioxide emissions in the hydrogenative gasification of lignite in the fluidized bed, characterized in that the hydrogenating gasification at 60 to 125 bar, preferably 70 to 125 bar, and 800 to 9500 C, preferably 850 to 9500 C, at least partially in countercurrent with coal and hydrogen a degree of carbon gasification of 45 to 70%, preferably 45 to 65%, and carries out under such a hydrogen partial pressure that the leaving the carburetor Raw gas has a hydrogen content of at least 25 vol .-%, wherein the Residence time of the coke in the gasifier to about 10 to 30 minutes, preferably 10 to 25 min., Sets.