Псевдогомогенді катализдік қоспа қатысындағы…
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5. Malyshev V.P. Matematical planning of metallurgical and chemical experiment. — Alma-Ata: Science, 1977. — Р. 36.
6. Malyshev V.P. Probably-determinative experiment planning. — Alma-Ata: Science, 1981. — 116 p.
UDC 662.75
Several Typical Coal Pyrolysis Technologies
Zhong Lin, Ma Feng-yun et al.
cent, to the processing and using th particles and condensation fault [3].
1.2. Toscoal technology
Toscoal technology, which dev perature coal pyrolysis technology w Non-bonding coal and Weak-bondin and preheated to 260–320 ºС by the with high temperature ceramics bal which discharged to the top of the heated ball and carbocoal separate ceramics ball through the bucket se pilot plant, but found in the test is d sion resistant [6]. In addition, the bo coal and weak-bonding coal can be u
Fig. 1. Sketch of flowchart of LR t Coal raiser; 2 — Coal hopper; 3 — 4 — Vessel; 5 — Cyclone; 6 — Ai Char raiser; 8 — Char collector; 9 — tor; 10 — Tar coll-ector; 11 — Du Gas cooler; 13 — Oil-water separato
1.3. DG pyrolysis technology DG pyrolysis technology, whic generation technology for lignite wi The craft system mainly consists o upgrade system, tar and gas recove 6mm, is added into the coal raiser a crude coal under rapid-heating, outl paration in the outlet of the raiser p air directly through the induced draf carbocoal powder about 800 ºC in 650 ºC complete pyrolysis in the py cyclone separator; and cooled and w separated in the vapor-liquid separat tor. Gas is collected as product after
The coal pyrolysis technology up in 1984, produced in 1990 and su al test equipment of coal pyrolysis 0.2–0.33 t/h, every tons of coal prod
he tar brings difficulties. Also, the use of coal ta
veloped based on U.S. oil shale distillation proce with ceramic balls as the carrier [4]. Its process i ng coal, which diameter less than 12.7mm, are a e hot flue gas [5]. The preheated coal go into the ll ensuring the pyrolysis temperature in 427–510 e separator, enter the vapor-liquid separator for through drum sieve in the separator, cinder fell end goal heater recycling. This process is compl due to the ball over 600 ºС heat cycle, the proble onding coal can paste in the ball in the pyrolysis, s
used for the process.
technology: 1 —
— Screw feeder;
ir preheater; 7 —
— Pyrolysis reac- ust catcher; 12 —
or
Fig. 2. Sketch of flowchart o 1 — Coal hopper; 2 — Coal 4 — Syrin-ge; 5 — Pyrolys carrier heater; 7 — Rotating separator; 9 — Char cooler;
rator; 11 — Heat carrier raiser
ch is put forward by Dalian university of technol th solid heat carrier. Raw coals are the lignite for f raw coal processing system, distillation system ery system, as shown in figure 3. The lignite, w
and mix with the hot flue gas about 550 ºC. In t let for 120 ºC, moisture less than 5 %. Materials pipe. The flue gas from cyclone separator about 2
ft fan after deducted. The dry coal enter the hopp the mixer. After mixing, the materials whose yrolysis reactor. The gaseous product from pyrol washed with the water about 80 ºC. The cooling tor, liquid materials achieve the oil-water separat r removing light tar and desulphurization [7].
projected by Dalian technology university of Ch ucceeds in gas production in 1992. Dalian techno
of coal processing capacity to do 3–6 t/h the au duction dry semi-coke 0.3–0.4 t, tar 0.02–0.03 t, g
ar for bonding caused by
ess Tosco-, is a low tem- s shown in figure 2. The added into the coal raiser e rotating drum and mix 0 ºС. Gas and tar steam, further separation. The on below the sieve and eted in 1970s per 25 t/d ems existing in the abra- so only the Non-bonding
of Toscoal technology:
l raiser; 3 — Cyclone;
sis Reactor; 6 — Heat g drum; 8 — Gas-solid 10 — Gas-liquid sepa- r
logy of China, is a Poly- r particle size of 0–6mm.
m, fluidization carbocoal whose diameter less than the hot flue gas carrying realize the gas-solid se- 2000C is discharged into per and mix with the heat temperature up to 550–
ysis is first separated by g gas and liquid mixture tion in the cinder separa- hina. The project started ology university industri-
uthor, coal consumption gas 200 m3.
Several Typical Coal Pyrolysis Technologies
1.4. ETCH pyrolysis technology
The ex-Soviet Union former did some research and development works on the pulverized coal pyrolysis with solid heat carrier. The ETCH pyrolysis technology which is used for the comprehensive utilization on power coal had test equipment about 4 ~ 6 t/h and an industrial test device about 175t/h in Krasnoyarsk pow- er plant [8]. ETCH-175 fast pyrolysis process flow diagram is shown in figure 4. Raw coal go to the pulve- rizer by the coal feeder, here provided the hot flue gas about 550 ºC. The powdered coal are delivered in the cyclone, at the same time, are heated to 100–120 ºC and the moisture less than 4. The dry coal entered the heater through the cyclone. In the heater, the coal mix with the heated powder chars and then paralyzes in the reactor. The volatile products are separated out in the pyrolysis reactor, and then are separated to tar, gas and condensed water. The char produced in the bottom of the pyrolysis reactor partly enter the raiser as heat car- riers. The temperature upper the reactor about 500–700 ºC. The surplus char produced in the system are dis- charged as power fuel after recovering heat.
The device tested a variety of lignite, moisture about 28–45 %, dry ash for 6–45 %. The char yield for 34–56 % used the dry coal, tar for 4~10 %, gas for 5–12 %, and water for 3~10 %.
Fig. 3. Sketch of flowchart of DG technology: 1 — Coal hopper; 2 — Mixer; 3 — Char raiser; 4 — Cyclone; 5 — Char hopper; 6 — Screw feeder; 7 — Pyrolysis reactor; 8 — Char cooler; 9 — Syringe;
10 — Gas-liquid separator; 11 — Tar tank; 12 — De- sulfuration
Fig. 4. Sketch of flowchart of ETCH technology:
1 — Coal hopper; 2 — Screw feeder; 3 — Pulve- rizer; 4 — Coal raiser; 5 — Combustion furnace;
6 — Char cyclone; 7 — Cyclone; 8 — Pyrolysis reactor; 9 — Char raiser; 10 — Char cooler; 11 — Coal cyclone
2. The evaluation for coal pyrolysis technologies
Fixed bed/moving bed of coal gasification or pyrolysis, which the coal use its own gravity in the reactor from moving, and complete gasification or pyrolysis, is a mature technology in industrialization degree, but its thermal efficiency is low, the environmental pressure is big, it is difficult to adapt to large-scale produc- tion, and due to the use of coal, grain to the increased cost of coal with grain, its technical economy gradually lowered.
Rotating furnace pyrolysis and gasification transmit heat faster, but there is serious phenomenon for dust deposition and blocking as continuous production process. The system is complex, energy consumption is high, and production capacity is limited, that there are many problems as continuous operation and is not fit for large scale producing.
Fluidized bed pyrolysis and gasification transmit heat rapidly and adapt for various kinds of coal, but the reaction bed is as shallow, that as disposing wide range of particle size distribution of coal, coal processing stage is uneven; causing the quality of thermal transition products is nonuniform.
Zhong Lin, Ma Feng-yun et al.
T a b l e Compare of the typical coal pyrolysis technologies
Technology Reactors Coal/particle size Heat carriers Products Scale LR Moving bed Lignite / 0–20mm Solid Char Char/Tar/Gas 1600 t/d
Industrialization Toscoal Revolving furnace Non/Weak-bonding
coal / 0–12.7mm
Solid Ceramic
Balls
Char/Tar/Gas 1000 t/d Industrialization DG Fluidized bed Lignite / 0–6mm Solid Char Char/Tar/Gas 150 t/d
Pilot scale test ETCH Entrained flow bed Lignite / Powder coal Gas Smoke Char/Tar/Gas 175 t/d
Pilot scale test Entrained-flow bed has rapid reaction for pyrolysis and gasification and it has high tar yield. The sys- tem is simple, but only small size of coal fit it.
3. Development trend of the coal pyrolysis technologies
At present, the importance and necessity of extracting liquid fuels and chemicals from coal using mild pyrolysis has known over all countries in the world. Pyrolysis is another kind of coal conversion process which can produce liquid products substituting crude oil. This technology is simpler, lower cost and wider adaptability for coal than coal liquefaction technology, although the yield of liquid products is lower.
Unfortunately, these pyrolysis technologies at home and abroad are most on the stage of pilot test or in- dustrial demonstration, yet still no commercial operation of coal pyrolysis technology. The existing pyrolysis technologies all have an insurmount ability defect that the tars contained much heavy components because of lacking technical measures to control the heating rate and the secondary reactions for oil and gas. These heavy components not only reduces grade and value the of coal and oil, but also cause a series of problems in operation, for example, it’s different to separate them from stive of the system. So its further industrialization is hindered.
From the above mentioned information, we can make a conclusion that the coal pyrolysis technologies have been developing in the following trend:
1) Raw coal particle has wide ranging and a great variety of coal is fit to be processed by the new coal pyrolysis technologies;
2) Large scale coal pyrolysis technologies are simply geared to enable the continuous production process;
3) Coal pyrolysis technologies have been on the path of energy-saving and green trend.
References
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