LOW TEMPERATURE PYROLYSIS METHOD OF CAKING MIDDLING COAL

Abstract

The present disclosure relates to the technical field of pyrolysis and improvement of caking middling coals, in particular to a low temperature pyrolysis method of a caking middling coal. The present disclosure provides a low temperature pyrolysis method of a caking middling coal, including the following steps: conveying the caking middling coal into a pyrolysis reactor through a top of the pyrolysis reactor; dividing a reaction chamber of the pyrolysis reactor into a drying section, a softening section, a melting and depolymerization section, a solidification section, and a cooling section by means of multi-channel gas distribution; and conducting zoned temperature control-based pyrolysis to obtain semi-coke at a bottom of the reactor as well as tar and coal gas at the top of the reactor. The pyrolysis method can well avoid caking and swelling of the caking middling coal during pyrolysis.

Claims

1. A low temperature pyrolysis method of a caking middling coal, comprising the following steps: mixing the caking middling coal with a non-caking coal to obtain a mixture; conveying the mixture into a pyrolysis reactor through a top of the pyrolysis reactor; dividing a reaction chamber of the pyrolysis reactor into a drying section, a softening section, a melting and depolymerization section, a solidification section, and a cooling section by means of multi-channel gas distribution; and conducting zoned temperature control-based pyrolysis to obtain semi-coke at a bottom of the reactor as well as tar and coal gas at the top of the reactor; wherein the drying section has a temperature of less than 143? C.; the softening section has a temperature of 345? C.; the melting and depolymerization section has a temperature of 447? C.; the solidification section has a temperature of 507? C.; and the cooling section has a temperature of less than 52? C.; the multi-channel gas distribution comprises: providing a first circulating carrier gas channel, a second circulating carrier gas channel, a third circulating carrier gas channel, a fourth circulating carrier gas channel, and a fifth circulating carrier gas channel in sequence from bottom to top on a side wall of the pyrolysis reactor; and introducing a circulating carrier gas into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel separately; the circulating carrier gas has a carrier gas flow rate of 1,200 m.sup.3/h, 250 m.sup.3/h, 500 m.sup.3/h, 250 m.sup.3/h, and 50 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively; the non-caking coal has a caking index of 32.30, an ash content Adaf of less than or equal to 27.5 wt %, and a volatile content Vdaf of 29.61 wt %; and the caking middling coal has a particle size of 30 mm to 80 mm.

2. The pyrolysis method according to claim 1, wherein the circulating carrier gas comprises a waste gas produced by the zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows a structural schematic diagram illustrating the pyrolysis reactor of the present disclosure.

[0021] Reference numerals: 1-first circulating carrier gas channel, 2-second circulating carrier gas channel, 3-third circulating carrier gas channel, 4-fourth circulating carrier gas channel, 5-fifth circulating carrier gas channel, 6-cooling section, 7-solidification section, 8-melting and depolymerization section, 9-softening section, 10-drying section, 11-semi-coke outlet, 12-material inlet, 13-coal gas and tar outlet.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present disclosure provides a low temperature pyrolysis method of a caking middling coal, including the following steps: [0023] conveying the caking middling coal into a pyrolysis reactor through a top of the pyrolysis reactor; dividing a reaction chamber of the pyrolysis reactor into a drying section, a softening section, a melting and depolymerization section, a solidification section, and a cooling section by means of multi-channel gas distribution; and conducting zoned temperature control-based pyrolysis to obtain semi-coke at a bottom of the reactor as well as tar and coal gas at the top of the reactor.

[0024] In the present disclosure, unless otherwise specified, all raw materials for preparation are commercially available products well known to those skilled in the art.

[0025] In the present disclosure, the caking middling coal has a caking index of preferably greater than or equal to 40 and an ash content of preferably greater than or equal to 30 wt %.

[0026] In the present disclosure, the method further includes preferably mixing the caking middling coal with a non-caking coal before the caking middling coal is conveyed into the pyrolysis reactor; where the non-caking coal has a caking index of preferably less than or equal to 10 and an ash content of preferably less than or equal to 15 wt %. The mixing preferably refers to mechanical mixing; there is no special limitation on a method of the mechanical mixing, which can be conducted in a way well known to those skilled in the art.

[0027] In the present disclosure, the caking middling coal and the non-caking coal are at a mass ratio of preferably (5-9):(1-5), more preferably 5:5, 6:4, 7:3, 8:2, or 9:1.

[0028] In the present disclosure, the caking middling coal and the non-caking coal have a particle size of independently preferably 10 mm to 90 mm, more preferably 30 mm to 80 mm.

[0029] In the present disclosure, when a mixture of the caking middling coal and the non-caking coal is used as a raw material for pyrolysis, there is interactions between the caking middling coal and the non-caking coal during the pyrolysis. The non-caking coal particles block the fluidity of colloids produced by heating the caking middling coal, thus further reducing a tendency of coal particles to stick together. In addition, this mechanism can further reduce an ash content of the prepared semi-coke, strengthen mechanical properties of the semi-coke, and effectively improve a quality of semi-coke products.

[0030] In the present disclosure, the multi-channel gas distribution includes preferably: providing a first circulating carrier gas channel, a second circulating carrier gas channel, a third circulating carrier gas channel, a fourth circulating carrier gas channel, and a fifth circulating carrier gas channel in sequence from bottom to top on a side wall of the pyrolysis reactor; and introducing a circulating carrier gas into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel separately.

[0031] In the present disclosure, the circulating carrier gas includes preferably a waste gas produced by the zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air. The circulating carrier gas has a temperature of preferably 750? C.

[0032] In the present disclosure, the circulating carrier gas has a carrier gas flow rate of 1,200 m.sup.3/h, 200 m.sup.3/h to 250 m.sup.3/h, 300 m.sup.3/h to 500 m.sup.3/h, 200 m.sup.3/h to 250 m.sup.3/h, and 50 m.sup.3/h to 100 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively.

[0033] In the present disclosure, the drying section has a temperature of preferably less than 180? C.; the softening section has a temperature of preferably 150? C. to 395? C., more preferably 200? C. to 300? C., most preferably 230? C. to 260? C.; the melting and depolymerization section has a temperature of preferably 350? C. to 500? C., more preferably 380? C. to 430? C.; the solidification section has a temperature of preferably 500? C. to 900? C., more preferably 600? C. to 800? C.; and the cooling section has a temperature of preferably less than 80? C.

[0034] The present disclosure further provides a pyrolysis reactor, including a first circulating carrier gas channel, a second circulating carrier gas channel, a third circulating carrier gas channel, a fourth circulating carrier gas channel, and a fifth circulating carrier gas channel that are arranged in sequence from bottom to top on a side wall of the pyrolysis reactor.

[0035] In the present disclosure, the pyrolysis reactor further includes preferably a material inlet and a coal gas outlet that are arranged at a top of the pyrolysis reactor (as shown in FIG. 1).

[0036] The low temperature pyrolysis method of a caking middling coal provided by the present disclosure are described in detail below with reference to the examples, but these examples may not be understood as a limitation to the protection scope of the present disclosure.

Example 1

[0037] Reaction raw materials were shown in Table 1:

TABLE-US-00001 TABLE 1 Physical parameters of caking middling coal and non-caking coal Ash content Volatile content Caking Particle Coal material A.sub.daf, wt % V.sub.daf, wt % index size, mm Caking middling 34.24 27.10 41.5 30-80 coal Non-caking coal 7.47 33.93 6.2 30-80

[0038] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0039] The caking middling coal and the non-caking coal were mechanically mixed at a mass ratio of 5:5 to obtain a mixture, and the mixture had a caking index of 25.3.

[0040] The mixture was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 200 m.sup.3/h, 300 m.sup.3/h, 200 m.sup.3/h, and 100 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 165? C.), a softening section (at 371? C.), a melting and depolymerization section (at 458? C.), a solidification section (at 544? C.), and a cooling section (at 65? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 27.64 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

Example 2

[0041] Reaction raw materials were shown in Table 1:

[0042] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0043] The caking middling coal and the non-caking coal were mechanically mixed at a mass ratio of 6:4 to obtain a mixture, and the mixture had a caking index of 29.52.

[0044] The mixture was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 200 m.sup.3/h, 350 m.sup.3/h, 200 m.sup.3/h, and 100 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 158? C.), a softening section (at 374? C.), a melting and depolymerization section (at 461? C.), a solidification section (at 551? C.), and a cooling section (at 57? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 29.35 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

Example 3

[0045] Reaction raw materials were shown in Table 1:

[0046] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0047] The caking middling coal and the non-caking coal were mechanically mixed at a mass ratio of 7:3 to obtain a mixture, and the mixture had a caking index of 32.33.

[0048] The mixture was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 200 m.sup.3/h, 400 m.sup.3/h, 200 m.sup.3/h, and 100 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 156? C.), a softening section (at 372? C.), a melting and depolymerization section (at 453? C.), a solidification section (at 532? C.), and a cooling section (at 55? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 33.17 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

Example 4

[0049] Reaction raw materials were shown in Table 1:

[0050] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0051] The caking middling coal and the non-caking coal were mechanically mixed at a mass ratio of 8:2 to obtain a mixture, and the mixture had a caking index of 35.81.

[0052] The mixture was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 200 m.sup.3/h, 450 m.sup.3/h, 250 m.sup.3/h, and 50 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 167? C.), a softening section (at 395? C.), a melting and depolymerization section (at 442? C.), a solidification section (at 542? C.), and a cooling section (at 57? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 35.02 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

Example 5

[0053] Reaction raw materials were shown in Table 1:

[0054] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0055] The caking middling coal and the non-caking coal were mechanically mixed at a mass ratio of 9:1 to obtain a mixture, and the mixture had a caking index of 36.82.

[0056] The mixture was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 250 m.sup.3/h, 500 m.sup.3/h, 250 m.sup.3/h, and 50 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 163? C.), a softening section (at 368? C.), a melting and depolymerization section (at 453? C.), a solidification section (at 527? C.), and a cooling section (at 55? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 35.73 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

Example 6

[0057] Reaction raw materials were shown in Table 2:

TABLE-US-00002 TABLE 2 Physical parameters of caking middling coal and non-caking coal Ash content Volatile content Caking Particle Coal material A.sub.daf, wt % V.sub.daf, wt % index size, mm Caking middling 27.5 29.61 32.30 30-80 coal

[0058] Pyrolysis method (conducted in the pyrolysis reactor in FIG. 1):

[0059] The caking middling coal was conveyed into the pyrolysis reactor through a top of the pyrolysis reactor. During the pyrolysis, a waste gas produced by zoned temperature control-based pyrolysis and a flue gas produced by mixed combustion of air were introduced into the pyrolysis reactor through the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel by multi-channel gas distribution, and were used as a circulating carrier gas (at 750? C.). The circulating carrier gas had a carrier gas flow rate of 1,200 m.sup.3/h, 250 m.sup.3/h, 500 m.sup.3/h, 250 m.sup.3/h, and 50 m.sup.3/h in the first circulating carrier gas channel, the second circulating carrier gas channel, the third circulating carrier gas channel, the fourth circulating carrier gas channel, and the fifth circulating carrier gas channel, respectively. A reaction chamber of the pyrolysis reactor was divided into a drying section (at 143? C.), a softening section (at 345? C.), a melting and depolymerization section (at 447? C.), a solidification section (at 507? C.), and a cooling section (at 52? C.), and the zoned temperature control-based pyrolysis was conducted to obtain semi-coke (with an ash content of 32.25 (A.sub.d, wt %)), and the semi-coke was discharged smoothly from a bottom of the furnace. Tar and coal gas produced by the pyrolysis were discharged from a top of the furnace by the carrier gas, and tar and gas products were obtained after separation and cooling.

[0060] The above are merely preferred implementations of the present disclosure. It should be noted that several improvements and modifications may further be made by a person of ordinary skill in the art without departing from the principle of the present disclosure, and such improvements and modifications should also be deemed as falling within the protection scope of the present disclosure.