Liquefaction of sub-bituminous and lignitic coal

The present invention relates to a process for the liquefaction of brown and / or lignite coal,

There are known processes by which coal can be converted into valuable products, by solvent extraction, in order to obtain a mixture of coal extract and undissolved coal residues, according to known processes, the hydrolysis of the coal is done with a soaking solvent. , coming from the coal liquefaction process, this remover solvent generally having a boiling range between about 314 and about 482 ° C. The mixing solvent and coal are then hydrogenated in the presence of a coal liquefaction catalyst. The procedures generally known in the art were intended in a manner¹ specifically, for liquefying bituminous coal. In trying to apply this - known - technology to lower quality coal, ie brown and / or lignite coals, it has been found that the known technology needs improvement in order to obtain an effective process.

The process for liquefying brown and / or lignite coals, according to the present invention, by filling in a solvent from^: from the coal liquefaction process, it eliminates the disadvantages of the known processes, in that the liquefaction is carried out, first, in a first step of softening the coal in the soil.⁵ vent, at temperatures of at least 260 ° C, preferably between 288 and 400 ° C, and at pressures of at least 27 kgf / cm², thus removing at least 10 respectively between 45 and 60% of. oxygen¹⁰ content, following the second stage of hydrolytic extraction, at temperatures between 314 and 482 ° C and at pressures between 35 and 280 kgf / cm², the mixing solvent used containing at least 25% mi15, preferably between 35 and 70% boiling point components above 425 ° C and at least 5%, distilling at temperatures of at least 288 ° C.

The following realization examples are given, in relation to the figure, which shows the diagram of the simplified technological flow, according to the present invention.

Example 1. A brown coal and / or lignite mill, partly dry- (3 ... 15-% ²⁵ humidity), such as, for example,. brown coal is fed through a pipe 1, is introduced into a zone 2 - for coal suspension, in which the coal is_3Q suspended in a settling solvent that comes through a pipe 3. The settling solvent is a solvent containing

LEI PRICE 11.09 at least 25% by weight components boiling over 427³C. The suspension of coal in the settling solvent is generally carried out at a temperature between about 66 and about 232 ° C, in order to obtain a suspension of coal in the settling solvent containing between about 25 and about 45% by weight of coal, iii the suspension operation water vapor can be released and these water vapors are usually released from the suspension area.

The suspension or dispersion of coal in the settling solvent is removed from the suspension zone 2, through a pipe 4, and is introduced into a plasticizing zone 5, in which the coal suspension is thermally plasticized to perform the deoxygenation of the coal, the deoxygenation products. being removed from the plasticizing area. The plasticizing zone operates under the conditions described above for removing at least 10%, generally between about 15 and about 60% of the organic oxygen compounds existing in coal.

A partially deoxygenated coal paste is removed from the plasticizing area 5, through a pipe 6. it is introduced into a liquefaction zone 7, together with a gas containing hydrogen, brought through a pipe S. Of course, the gas contained in hydrogen and the coal paste can be pre-mixed before being introduced into the liquefied area 7. liquefaction contains a catalyst and works under the conditions described above for liquefaction of brown and / or lignite coal. The liquefaction zone 7 is preferably a reactor, with an expanded bed rising, comprising 2 ... 3 reactors in series. Of course, however, other types of reactors can be used in the liquefaction area.

The gaseous products are removed from the liquefaction area through a pipe 9, and through a pipe 10 a coal liquefaction product is removed. In some cases, part of the liquefaction product is recycled through pipe 11, although in most cases no recycling is required.

The net liquefaction product in a pipeline 12 is introduced into a distillation area 13, to separate it from the easier components. Generally, the zone 13 works for the distillation of some materials boiling to about the final boiling point of a liquid that favors the release and is used in the subsequent release phase. Generally, the components more volatile than at about 288 ... 315 ° C are removed in the separation zone 13 by a conduit 14, these products for4 being part of the net coal liquefaction product. Through a pipe 15, from. zone 13 a residual product is removed and some of it may be recycled in the suspension zone 2 and / or in the laminating area 5. In general, recycling through a pipe 16, if any, does not occur if the product contains more than about 15% by weight of total solids. The product remaining in a pipe 17 is introduced into a mixing zone 18, wherein the product is mixed with a liquid that favors the trigger that comes through a pipe 19. The liquid that favors the trigger is of the commonly used type. The promoter fluid has a characterization factor (K) of at least about 9.75 and, preferably, at least about 11.0. The promoter liquid used to improve and promote the separation of insoluble material from the coal liquefaction product is characterized by a 5% by volume distillation temperature of at least about 120 ° C and a 95% distillation temperature by volume of at least about 177C and not more than about 400 ° C, the promoter liquid having a 5% volume distillation, at a temperature of at least 155 ° C_r and preferably at least 205'C. The distillation of 95% by volume takes place at a temperature, preferably not higher than about 315 ° C. The most preferred promoter liquid has a distillation of 5% by volume, at a temperature of at least about 215 ° C and a distillation of 95% by volume at a temperature of not more than about 255 ° C. The promoter fluid is preferably used in an amount representing a weight ratio of the promoter fluid to the coal liquefaction product between about 0.5 and about 1.0.

The mixture of coal liquefaction product and promoter liquid, extracted from the mixing zone 18 through a pipe 20, is introduced into a release zone 21, in which a particularly free, ash product is separated from an ash-containing product. of coal. The release zone 21 preferably contains one or more gravity separators, the gravity separation being preferably carried out at a temperature between about 205 and about 315 ° C. An overflow product, especially free of insoluble material, is removed from the trigger zone 21, through a conduit 22, and introduced into a cry zone 23 for the recovery thereof of the promoter fluid. The promoter fluid is removed from the striping area 23 through a pipe 24 in combination with fresh promoter fluid in a pipe 25, at -ne72148, and is introduced into the mixing zone: 18 through pipe 19. The rest of the overflow product is divided into two currents, one of the currents being used in pipe 3 as a setting solvent for the liquefaction process. A part of the settling solvent can be inserted, at will, into the laminating area 5 through a pipe 26. The remainder of the product, ie the unused part as a settling solvent, is recovered, as a net product, through a pipe 27. An ash-enriched bottom stream is removed 'from the triggering area 21 through a pipe' 28 and a stripping area 29 is introduced to retrieve it from the promoter liquid. - The promoter liquid is removed from the stripping area 29 through a pipe 30 and recycled into the mixing area 18. The remaining product enriched in ash is removed from the stripping area 29 through a pipe 31, for further processing. Thus, for example, the current enriched in ash from pipe 31 can be subjected to coking and / or gasification. The form of execution described above^: can consequently modify its invention; The front is not limited to such an embodiment, so for example, although the coal liquefaction product is preferably off, as described, the downtime can be done and other working methods first.

Considering another modification, although, through the general process, preferably the deoxygenation and liquefaction • aspects of the present invention are combined, it is of course understood that, in some cases, a general process may be provided, whereby liquefaction can be carried out without the use of a self-mixing solvent, which means that the blending solvent for liquefaction of brown and / or · lignitic coals must not contain heavier components, As described herein, the present invention will be described in more detail in the light of the following examples.

Example 2. A coal slurry, consisting of · 429 g brown coal, its analysis is given in table 1, and 1000 g of hydrotreated lignite tar at ^:288 ° C is suspended in a glass of Berzei ius of 2 1 at 93 ° C. The prepared mixture is then placed in an electrically heated pump, washed with^; nitrogen and provided with mi -ooiitrapr.esiunel regulator · The pump is closed ȘL under the supervision of the regulator, if^r- creates a pressure of about 10 kgf / cffi² and in the vapor space of the bomb, hydrogen gas is introduced. The residual gas in the bomb is cooled and passed into a water-cooled separator. The non-condensable gas in the separator is passed through an integration flowmeter and collected in a rubber gas bag. The liquid content of the bomb, after closure, is heated to 314 ° C for about 15 minutes and maintained at 314 ° C for about 20 minutes. At the end of this time, the integration flow meter is read, and the gas bag detaches and closes. The composition of the waste gas in the gas bag is analyzed. The total amount of carbon dioxide escaping the residual gas is calculated from the above analysis and the total molar quantity of the residual gas is determined using the integration flowmeter. In this experience, in the form of carbon dioxide, about 26% of the organic oxygen found in the coal batch is released.

^: Example 3. Repeat example -2, using as a batch for a bomb of 2 1000 g of hydrated lignite coal tar · at 288 ° C, - used in example 2 - without addition; During this experience, in the composition of the residual gas · -hu was found - at all carbon dioxide.

Exemplul'4. In a shaker container and with a steam jacket, prepare - at 84'C carbon paste of -30% by weight brown coal (table · 1) and 70% by weight of the solvent of mixing (table 2). The first solvent for settlement comes from hydrotreated brown coal tar, considered as solvent-proper. This coal paste is introduced into a heating coil, with the help of a proportioning pump, in which it is. mix with a high pressure hydrogen rich gas. Temperature of the mixture; of carbon paste and hydrogen-rich rises to about 288 "G in. heater. This mixture, in turn, is continuously passed into a catalytic hydrolyzing reactor in the form of upstream. Conditions of; work in the reactor is given in table · 3. The product leaving the reactor is collected in a high pressure separator with the hot water mist / receiving vessel, in which a gas and a liquid phase are separated. The gas is allowed to flow continuously from the inlet pressure separator / receiving vessel through a pressure control valve. After the liquid content of the high pressure separator / receiving vessel is approx

80% of the available volume of the high pressure separator / receiving vessel, the product coming out of the reactor is directed to a second high pressure separator / receiving vessel - identical, - - I was pressured - I help 72148 the role of a rich hydrogen gas, up to the working pressure. The contents of the first high pressure separator / receiving vessel are then allowed to flow into a liquid product receiving vessel.⁵low pressure with the steam jacket, which works at atmospheric pressure. The liquid product from the low pressure product is passed into a stirred storage tank with a steam mania. The above series of operations are repeated and thus the reactor operations are carried out continuously.

The continuous experience with brown coal, described in this example, ends, ¹⁵at will, after about 48 hours of work.

A representative sample of the liquid product solution is removed from the storage tank with the agitator and the volumetric quantity of the product solution is ²⁰ ends with the temperature in the storage tank. On the solution of representative liquid product above is determined the ash content (ASTM D-482), the insoluble content in²⁵ quinoline (ASTM D-2318) and specific weight (ASTM D-287) at different temperatures. From the first analysis and the weight of the combined solution of liquid product, it is found that about 83 + 1% of the 30 coals as dry mass passed into the hydrolyzing reactor have been converted to a quinoline-soluble form, which can be used as a measure for the degree. of liquefaction. During the entire 35-hour working period of 48 hours, a pressure drop in the reactor of 1.5 ... was observed.

1.75 kgf / cm².

Example 5. Repeat Example 4, using a setting solvent ⁴⁰lighter, denoted by II, whose composition data are given in table 4. This setting solvent also comes from the hydrotreated brown coal tar, All conditions. ⁴⁵The working conditions in this example are identical to those used in Example 3, except for the setting solvent used. Table 3 is a compilation of the conditions in the hydrolysis process⁵⁰used in this example.

About 15 min after starting the carbon feed, the pressure drop in the reactor increases rapidly from 1.5 ... 1.75 kgf / cm² about normal ⁵⁵21 kg / cm². Then, in the unit, a heavy crucible oil is passed, derived from the bituminous coal deposited in an additional feed tank and the paste: 'coal, is fed in the way₆₀discontinuous. The hydrolyzing reactor is evacuated until the press ure-drop in the reactor: it is restored, to a value of 1.5., 11.75 kgf / cm². Then, the arrival of the crucible oil is stopped and the reactor is refueled with the previously used coal paste. About 15 minutes after the second introduction of coal paste, the pressure drop in the reactor rises rapidly to a value greater than 21 kgf / cm². The coal-age hydrolysis unit stops at this time. After depressurization, cooling and washing with nitrogen, the reactor is opened and the bottom of the catalyst bed is visually examined. It is observed regions containing numerous accumulated brown carbon particles. The coal particles are presented as not being dispersed from the settling solvent at the bottom of the catalyst bed, which greatly reduces the bed's permeability.

Table 1

Analytical slabs for dry milled brown coal

Year-α! he is about to die you Humidity, »/₀ by weight Volatile matter,% by weight Ash o / w by weight Coal f-ix,% by weight

Final analysis (taken as a basis) Water, ^of/ o by weight Ash, o / o by weight Carbon% by weight Hydrogen, ° / o by weight (hydrogen deduced in water)

Nitrogen,% by weight Sulf, o / o by weight Oxygen, organic,% by weight (by difference)

Calorific power (relative to dry mass)

Higher calorific power Kcdl / kg

6,02

51,48

0,86

47,66

6,02

0,81

63,07

3,96

0,51

0,24

25,39

6150

Table 2

Analytical data for Jtnpăs solvent. hard (I) used in Example 4

<td colspan="3">Specific weight 55'C / 15 ° C Specific weight 10: rC / l 5'-C Content - ash% by weight C-sulfur-wetted% by weight Carbon content% by weight Hydrogen content by weight% You have nitrogen content% by weight Insoluble in benzene / o by weight</td><td> 1,0269 1,0224 0,17 0,44 85,86 9,35 0,49 1,5</td>

<td colspan="4">Vacuum distillation analysis</td>

<td>o / o from volume distilled</td><td>% by weight distilled</td><td colspan="2">The peak temperature of the vapor, C, corrected at 760 mmHg absolute pressure</td>

<td>0.0 L0 3.6 9.0 11.3 21.3 28 3 35.0 45.0 - 55.0 58.6 '</td><td> 0,0 3,29 8,22 10,41 20,07 26,76 34,47 : 44,05 53,40 56,56</td><td colspan="2">220 266 288 314 324 362 370 382 400. 417 '425 i. J 1 ''</td>

72143

10

Table 3

The parameters for the catalytic process of hydrolyzers used in examples 4 and 5

<td>Elbow dlraator</td><td>Fresh cobalt molybdate</td>

<td></td><td>on aluminum support</td>

<td>The form of the cure</td><td>Stereos with diameter! 2.5 ... 3 mm</td>

<td>Coal content in batch,%</td><td></td>

<td>by weight</td><td> 30,0</td>

<td>Mixing solvent used</td><td>see examples 4 and 5</td>

<td>Contact type</td><td>Reactor with expanded bed</td>

<td>Hourly volumetric speed hours ~^IT (volume</td><td> 1,7</td>

<td>tarjâ.'h / candy voilurn)</td><td>ifţrţ</td>

<td>Working pressure kgf / cm²</td><td></td>

<td>Hydrogen content in gas</td><td> 90</td>

<td>of feed,% in mol.</td><td></td>

<td>Inlet temperature in the reactor, ^cC</td><td> 288-314</td>

<td>Output temperature of the reactor, ° C</td><td> 415-420</td>

Table 4

Analytical data for setting solvent (II) used in Example 5

<td colspan="2">Specific weight 105 / 15'C</td><td></td><td> 0,9951</td>

<td colspan="2">Specific difficulties 48.5 / 15^cC</td><td></td><td> 1,007</td>

<td colspan="3">Ash content “/ o by weight</td><td> &lt;0,01</td>

<td colspan="3">Contains sulfur »/₀ by weight</td><td> 0,37</td>

<td colspan="3">Carbon content% by weight</td><td> 86,24</td>

<td colspan="3">Hydrogen content by weight%</td><td> 9,65</td>

<td>Content, d</td><td colspan="2">It is nitrogen ο / g by weight</td><td> 0,48</td>

<td colspan="4">'Vacuum distillation analysis</td>

<td>° / o in</td><td></td><td colspan="2">Tempenalfura of</td>

<td></td><td>% by weight</td><td colspan="2">peak of steam, ^cC</td>

<td>dis · *: He knows</td><td>say its tall</td><td colspan="2">I / 60 mm Hg,</td>

<td></td><td></td><td colspan="2">absolute pressure</td>

<td> 0</td><td> 0</td><td> 235</td><td></td>

<td> 3,4</td><td> 2,80</td><td> 250</td><td></td>

<td> 9,3</td><td> 8,75</td><td> 288</td><td></td>

<td>Ί9.2</td><td> 18,11</td><td> 314</td><td></td>

<td> 31,4</td><td> 29,98</td><td> 362</td><td></td>

<td> 45,7</td><td> 44,12</td><td> 370</td><td></td>

<td> 56,4</td><td> 54,48</td><td> 400</td><td></td>

<td> 66,4</td><td> ' '64,15</td><td> 405</td><td></td>

<td> 76 4</td><td> 73,78</td><td> 417</td><td></td>

<td> 82,6 .</td><td> 79,38</td><td> 425</td><td></td>

From the above examples it follows that, according to the present invention, an improved process for the hydrolysis of brown and / or li gnite coals has been developed, in which, prior to the hydrolysis phase, the coal is softened to remove at least part of the contents. of their organic oxygen.

According to a further aspect of the present invention, hydrolysis is carried out in a mixing solvent resulting from the hydrolysis of the brown and / or lignitic coals, the solvent; of storage containing at least 25% by weight of a material boiling above 425 ° C.

As is known in the art, brown coals comprise those coals that are in ASTM classification, III and lignite coals include those coals found in class IV ASTM, in particular brown coals and lignite.

According to the process of the present invention, the coal to be subjected to a hydrolysis process is partially deoxygenated or decarboxylated by hot dipping with carbon dioxide, water and small amounts of carbon monoxide as main products. Smaller quantities of oxygenated organic compounds and small quantities and light hydrocarbon gases (Q and C) may also be formed.₄). The softening of the coals before hydrolysis is done. provided that at least 10% of the organic oxygen contained in the charcoal is removed, this organic oxygen content of the charcoal being generally removed in an amount of between about 15 and about 60% or more. Hot soaking is generally performed at a temperature of at least 260 ° C generally between about 288 and about 400 ° C, and at a pressure lower than about 21 kgf / cm², generally, on the order of about 2 to about 21 kgf / cm². Thermal laminating is done for a sufficient period of time for the desired oxygen removal, this time period being generally between about 0.05 and 2 h.

It should be borne in mind that, although in one aspect of the present invention hydrolysis is performed in a particular type of mixing solvent, de. Oxygenation of brown and / or lignite coal can be done in mixing solvents, other than the type used, by prefe72148 rinse, in the subsequent hydrolysis phase. Pre-laminating brown coal and / or lignite to deoxygenate them minimizes non-_snet hydrogen cesarean section for hydrolysis. It has been found that brown and / or lignite coal generally have an oxygen content ranging from about 15 to about 30%, relative to dry mass,_1Qcompared to bituminous coals, which generally have an oxygen content of between about 4 and about 12% by weight, relative to the dry mass. Accordingly, by deoxygenating the brown and / or lignite coals, by the method according to the present invention, the hydrogen requirement for subsequent hydrolysis is reduced to a large extent.

according to the aspect of the invention _2θIn the present case, the hydrolyzing of brown and / or lignite coals is carried out with its own setting solvent, ie a mixing solvent from brown and / or lignite coals, it is a solvent containing at least 25% by weight by weight. ²⁵speakers - boiling above 425 ° C and preferably between about 35 and about 70% by weight components boiling over 425 ^ 0. The settling solvent shows, in. overall, 5% by volume, at room temperature³⁰distillation radius' of at least about 288 ° C, in the mixing solvent being able to also include components with lower boiling point, · ie - the dispersing solvent - may contain components · boiling below '288 ° C, if the settling solvent' includes at least 25% weighted components boiling above 425 ° C.^; Of course; the temperatures given above are all corrected Ta 1 of.

This 'aspect' of the present invention is based on the finding that the use of a solvent - of its own setting, comprising boiling components above 425 ° C in an amount of at least 25% by weight, ⁴⁵for hydrolyzing brown and / or 'lignite coal', it maintains coal in a dispersed state; whereas the use of a self-setting solvent, which does not comprise such heavier components,⁵⁰do it,^; -the coal - to be dispersed, fact'-through which they accumulate in the reactor-and¹ pressure drop through the reactor.

Hydrolysis of brown coal and / ⁵5 or licplitici · are performed, generally - at O ​​'· thmperbitură-' between 3 and 4 scififdaMSO'O; of '- preferably, between' around 358 and about 440 ° C, and¹ to^-a pressure between about 35 ^itand about- 280 -kgf / cm². Speed-'VAlumetrităc-tion⁵ you are 'liquid-typical'⁽eSteode &lt;οΎϊΪίηύΐΉΙε ••• cherry '0,^:3 pînăTâ'eiric &amp; ^ iO'h^1-1: '

Hydrolysis is generally carried out in the presence of a convenient hydrolysis catalyst which is generally either an oxide or a sulphide of metals in groups 6 or 8 deposited on a suitable substrate such as, for example, alumina or silica-alumina. . Preferred catalysts are cobalt molybdate, nickel molybdate and nickel and tungsten sulfide. The catalyst can be in the physical form of extrudates, tablets, spheres or particles of any shape and can comprise any granulation, this granulation, being between diameters of 6 and 0.6 mm. Contacting can occur by one of the methods known by the methods known in the art, which include added catalyst in powder form, a fixed bed of catalyst, a fluidized bed of catalyst, a boiling bed and the like. A preferred mode is an expanded bed in an upward flow. Hydrolyzing can be done in one or more reactors, the preferred arrangement of which is to insert 2 ... 3 reactors.

The present invention has multiple advantages, in that brown coal and / or lignite can be liquefied, without the use of increased quantities: of hydrogen, by executing a partial deoxygenation of the coal, as described. Furthermore, proceeding in accordance with the present invention, it is possible to use a carbon-filling solvent, while maintaining the coal dispersed in the settling solvent.