Note: Descriptions are shown in the official language in which they were submitted.
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1~17~
~'rHOD ~OR H~A~ PROC~SSING OF PU~V~RIZ~D
BRO',~ C3A~
The invention relates to methods for the destructive
processing o~ solid carbo~-containi~g materials, by breaking
down thereof and more specifically, to methods for heat pro-
cessing o~ pulverized brown coal~.
~ he invention is o~ particular advantage in energe-tic
and chemical industries where it can be used for combined
production of hi~h-calorific solid and synthetic liquid fuels
as well as other gaseous and liquid producbs whioh are subse-
quently processed into technical and chemical raw materials.
Background of bhe Invention
There are well known in the art methods for pyrolytic,
or heat processing of pulverized solid ~uels by the aid of
which both usable products, including solid as well as li~uid
products, and loY~-grade products, such as heavy tars and pyr-
ogenic water are produced.
on
~ hough the heat o~ combustion of heavy tars, the orderof 8400 k~al/kg, is known to be higher than thab o~ the pro-
duct being produced (whose heat of combustion is 6400-6700
kcal/kg), the utilization thereof presents a severe problem.
~his problem derives ~rom the ~act that under normal condi-
tions t~r is a sticky viscous substance which is neither too
~luid to be delivered through pipelines nor su~`ficiently solid
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to be loaded into and delivered by transporting facilities to the
consumer. Consequently, when heavy tar is used as a liquid boiler
fuel, it is to be transformed into a liquid by heating, which
naturally requires additional capital and operating expenses. Yet
here, too, the problem of delivering heavy tars to the consumer
stands.
Thus, due to heat processing of fuel, the product whose
heat of combustion is 8400 kcal/kg practically cannot be used as
fuel.
It is also known that pyrogenic water comprises approxi-
mately 4.5% phenols dissolved therein which are usable products.
However, to separate phenols from pyrogenic water, a complicated
procedure is to be resorted to, which, again requires considerable
capital and operating expenses. In addition, after the separation
of phenols from pyrogenic water the latter is to be purified prior
to disposal into a water pool.
As a consequence of the fact that world's natural ener-
gy resources are running thin, processing of large quantities of
low-grade fuels is gaining in importance. Specifically, ever more
acute becomes a problem of utilizing heavy tar and pyrogenic water
which are low-grade products resulting from heat processing of
fuels.
There is known in the art a method for heat processing
pulverized brown coal (Inventor's Certificate No. 335267 published
in 1972, in Bulletin No. 13 "Discoveries, Inventions, Industrial
Designs and Trademarks) comprising a first stage of heating the
coal by a gaseous heat carrier in less than one second to a tem-
perature of 200-
-3-
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i~l7~
5~0C with subsequent separating of the heat carrier from
the coal, a second stage of heating the coal by the gaseous
heat carrier in less than one second -to a temperature of 500-
800C at which an in-tensive thermal decomposition thereof
takes place with the formation of a vapour-and-gas suspension
consisting of a solid portion and a vapour-and-gas portion,
condensing the vapour-and-gas portion to obtain gas, valuable
li~uid products and to separate therefrom low-grade products,
such as heavy tars and pyrog~enic water.
'~he re~ization o~ the above method makes it possible to
produce along with other usable products also low-grade pro-
ducts such as heavy tars and pyrogenic water whose utiliza-
tion presents a problem not yet solved.
~ he object of the invention is to provide a method for
heat pxocessing of pulverized brown coal, which, with the
power input equal to that of the conventional methods ensures
the production of a solid product with higher heat combustion.
Another object of the present invention is to provide a
method for heat processing of pulverized brown coal, which
enables utilization of low-grade products.
One more object of the invention is to provide a method
for heat processing pulverized solid ~uel, which makes it
possible to realize pyrolytic processing o~ the heavy tar -
a product of heat processing o~ brown coal.
Still another object o~ the present invention is to pro-
vide a method for processing of pu~verized brown coal, which
7Q~9
ehables utili~ation of org~nic substances dissolved in pyrog-
enic v~ater.
Summary of the In~ention
~ hese and o-ther objects are achieved by the pro~ision
o~ a method for heat processing of` pulverized brown coal com-
prising a first stage of heating the coal by a gaseous heat
carrier in less than one second to a temperature of 200-500C
and subsequently separating the spent heat carrier frorn the
coal, a second stage o~ heating ~he coal by the gaseous car-
rier in less than one second to a tempexature o~ ~00-800C at
which temperature an intensive thermal decomposition of the
coal takes place with the formation of a vapour-and-gas sus-
pension containing a solid portion and a vapour_and-gas por-
tion, condensing the vapour-and-gas portion to obtain gas,
usable liquid product$ and to separate low-grade products,
such as heavy tars and pyrogenic water therefrom, wherein,
according to the invention, at the second stage R heating
the low-grade products of heat processing of pulverized brown
coal are sprayed into the stream of`the gaseous carrier con-
taining air oxygen.
It is expedient to supply bhe stream of thc gaseous heat
carrier v~ith heavy tar? the oxygen oontent in bhe gaseous car-
rier being sufficient for carrying out pyrolybic processing of
the heavy tar at predetermined temperatures. Due to pyroly-tic
processing of the heavy tar, volatile components are liberat-
ed which burn and thereby raise the temperature of ~he gaseous
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1~17C~9
heat carrier. In addition, there is formed a solid portion
v~hich is a high-calori~ic ~uel.
It is good pxactice to supply the stream of the gaseous
heat carrier with pyrogenic water, the gaseous heat carrier
being supplied along the stream thereof, first ~ith pyroge-
nic water and then with heavy tars, ~his prevents the neces-
sity in purifying p~rogenic water prior to disposal thereof
into water pools. In addition, organic solvents dissolved in
pyrogenic: water can be converted into usable products.
Brie~ Description of the Drawings
~ he above-mentioned and other object o~ this invention
will become more apparent-by reference to the following des-
cription of an embodiment of the invention taken in conjunc-
tion with the accompanying drawing which show~ a diagrammat-
ic view of an apparatus for heat processing of pulverized
bro~ coal.
Description of the Preferred Embodiment
of the Invention
~ ihen realizing the method for heat processing of pulver-
ized b~own coal, there is used an apparatus comprizing a
chamber 1 adapted ~or the ~irst-stage heating of coal. The
apparatus has a hopper 2 communicating with the cha~ber 1
through a turnstile ~eeder 3. A co~nection pipe 4 of a devi-
ce ~not shown) ~or feeding ~he gaseous heat carrier t~ngen-
tially adaoins the chamber 1. ~o discharge the spent gaseous
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i~7~9
heat carrier, the chamber I is provided with a pipe 5 coa-
~ially installed therein and connected with a cyclone (not
shown). A chamber 7 adapted ~or the second-stage heating of
the ~uel is s~ccesively connected to the chamber I ~hrough a
~eeder 6. Abut-tin~ the cha~ber 7 adapted for the second-
-stage heating of the coal is a means 8 ~or deli~ering the
gaseous heat carrier into ~he chamber 7, the stream of the
gaseous heat carrier being supplied with low-grade products.
The means 8 is a pipeline 9 tan~entially adjoining the cham-
ber 7 adapted for the second-stage heatin~ of the coal. ~he
~ v.el
pipeline 9 is provided with a chamber 10 ~or to be burnt
therein a~d -to form stack gas, with chamber II ~or pyrogenic
water to be ~ed thereto through sprayers 12, and with a
chamber 13 ~or heavy tars to be fed thereto throu~h sprayers
14. '~he chamber 10 incorporates a burner 15 adapted to burn
fuel in a mixture with air oxy~en.
To discharge the vapour-and-gas mixture resulting ~rom
thermal decomposition of the brown coal, the chamber 7 adap- -
ted for the second-stage heating o~ fuel is provided ~ith a
pipe 16 coaxially positioned therein and connected with a
cyclone (not shown) throu~h a pipeline. Furthermore, the
chamber 7 adapted ~or the second-stage heating o~ the brown
coal is provided with a turnstile metering device 17 adapted
to discharge the obtained solid product ~rom the chamber 7.
According to the invention, the method for heat process-
in~ o~ pulverized brown coal is realized as follows.
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~17(~49
~ he pulverized brown coal having the size of prticles
below I mm is preheated to a temperature about 110C for dry-
ing and is -thereafter fed by the feeder 3 from the hopper 2
into the chamber I adapted for the first-stage heating of the
brown c~al. Simultaneously an oxygen-~ree heat carrier in the
form o~ stack gas having a temperature o~ no less than 500C
is delivered into t~e chamber I through the connection pipe 4.
~ he heat carrier tangentially enters the chamber I adap-
ted for the first-stage heating of the brown coal and draws
the particles of the pulverized bxown coal. Under the action
o~ centri~ug~al and gravity forces the brown coal particles
are thrown towards the wall o~ the chamber and descend in a
~ortex. ~he pulverized brown coal is heated by the heat car-
rier to a temperature o~ 200 to 500C. ~he spent gaseous heat
carrier cooled down to a temperature about 350C is discharg-
ed through the pipe 5 into the cyclone (not shown). A portion
of the pulverized brown coal carried away by the heat ca~rier
is separated there~rom in a conventional manner.
~ he feeder 6 feeds the brown coal being processed from
the chamber I adapted ~or the ~irst stage heating o~ the brown
coal into the chamber 7 adapted ~or the second stage heatin~
o~ the brown coal. Concurrently with the coal the gaseous
heat carrier is ~ed into the chamber 7 adapted ~or the second-
-sta~e of heating through the means 8. According to the inven-
tion the gaseous heat carrier obtained by burning a fuel, such
as gas, and by the ~ormation of stack gas is supplied with low-
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~117~49
-~rade products. ~his procedure is carried QUt in the follovJ-
ing way.
A combustible gas or any other fuel mixed with air oxyg-
en is ~ed into a burner 15. Iviore than 50% of the combustible
gas is burnt in the chamber 10, thereby forming a gaseous
heat carrier containing air oxygen. Since approximately 50%
of combus~ible substance are burn-t in the chamber 10 wherein
the heat carrier is ~ormed, the temperature in this chamber
reaches about 1200C. It is ~o be noted that the process o~
burning and the temperature in the chamber 10 wherein the
heat carrier formation takes place are regulated in a conven-
tional manner and by conven~ional means and there~ore should
be clear to those skilled in the art. From the chamber 10
wherein the heat carrier formation takes place, the gaseous
heat carrier enters the chamber II adapted for processing
pyrogenetic water. Simultaneously the stream of ~he gaseous
heat carrier is supplied with pyrogenic water through the
sprayers 12. In the chamber II adapted for processing pyrog-
enic water, there takes place evaporation of the water as
well as oxidati~e pyrolysis of organic substances dissolved
therein, in particular, phenols. On pyrolysis of or~anic
substances, one portion thereof gets transformed, another
portion burns, still another is deposited as carbon on pulve-
rized particles of the obtained coke. Due to processing of
the pyrogenic water, the temperature of the gaseous heat car-
rier drops to about 1000C. ~he gaseous heat carrier having
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~17Q~9
the tem~erature of 1000C is fed into the chamber 13 where
processing of heavy tars takes place~ The chamber 13 is con-
tinuously supplied through the sprayers 14 with heav~ tars
which constitute a liquid after being heated. Due to the
high temperature and oxidizing medium (the stream of the ga-
seous ~eat carrier contai~s oxygen), there takes place oxid-
ative pyrolysis of heavy tars in the chamber 13. r~his being
the case, partial conversion of the li~uid organic compounds
occurs, and the gas goes on burninæ. As a result of after-
burning of gas and partial burning of the combustibles sepa-
rated after the decomposition of heavy tars, the temperature
of the heat carrier rises to 1200C~ ~he gaseous heat car-
rier together with solid-particles contained therein which
have been obtained as a result of thermal processing o~ the
pyrogenic water and heavy tars enters -the chamber 7 adap~ed
for the second-stage heating of the coal whereupon oxygen of
the gaseous heat carrier fully reacts and -che heat carrier
the
becomes mixed with brown coal being processed which is fed by
the feeder 6. Solid particles of the brown coal are whirled
by the gaseous stream moving from the centre of the chamber 7
to its periphery through the hot gaseous heat carrier.
The gaseous hea-~ carrier, giving up its heat to the brown
coal heats i5 to a temperature of 500-800C. ~his being the
case, there takes place an intensive thermal decomposition of
the brown coal, giving a vapour-and-gas suspension containing
a solid product (coke) in the form of pulverized particles
and a vapour-and-gas mixture. ~he ob-cained solid product is
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~ ~ 17 ~ ~
discharged from the cnamber 7 adapted for the seconà-stage
heating of the brown coal by a turnstile metering device 17.
Simultaneously, the obtained vapour-and-gas mixture is di-
scharged into a cyclone (not show~) through a pipe 15 to be
purif ied from solid par-ticles. ~'he purified vapour-and-gas
suspension is delivered for condensation to yield usable liq-
uid products and for separation of low-grade products in the
form of heavy tars and pyrogenic water from those usable
li~uid products. ~hus obtained lo~J-grade products such as
heavy tars and pyrogenic water are directed respectively,
into the chamber II and the chamber 13 to be fed into the
stream of the gaseous heat carrier.
Example
3rown coal having the calorific value of 3500 kcal/kg,
moisture content of ~2 to 38%, ash content of 8% and sulphur
content of 0.5% was pulverized until the size of particles
was less than one mm, and preheated to a temperature of 110C.
~ he thus obtained brown coal was delivered into chamber I
for heating in a vor-tex stream by a gaseous heat carrier such
as stack gas having a temperature of not lower than 500C.
In fractions of a second (about 0.3 sec) the coal ~las heated
to a tempera-ture of 200-500C, i.e. to the -tempera-ture at
vlhich thermal decomposition of the coal begins. Being heated
so fast, the coal practically did not change its com~osition
because one ton of the coal being processed yielded but 2~ kg
of mass consisting of pyrogenic water, gas and coal carry-off.
~117~49
The s?ant gaseous heat carrier having a temp~rature of about
350 ~as separated from the heated cDal.
leated t~ the temperature o~` the beginnin6r of thermal
decomposition, the coal was delivered into chamber 7 adapted
for the second-stage heating of the brown coal where was heat-
ed by the gaseous heat carrier havi~g a temperature of about
1000C. During 0.3 sec the brown c~al was heated to a tempera-
ture of 500-800C. AccDrding to the invention the stream of
the gaseous heat carrier cDntaining 100 kg of air per 10 kg
of combustible gas was supplied with 50 kg of pyrogenic water
per ton. Concurrently with burning o~ gas, there took place
evaporation of the water as well as sejaration and oxidative
pyrDlysis of organic substances dissolved in the water q'hus,
though evaporation o~ the water generally requires about
600 kcal/kg, in this case, due to combustion of phenols dissol-
ved in the pyrogenic water, the cDnsumption of energy for
t~e evaporation constituted but 150-200 kcaltkg. Furthermore,
thermal decomposition of phenols resulted in the formation of
an insoluble residue. 75 kg of pulverized heavy tars were in-
troduced into chamber 13 through sprayers 14 to be fed into the
gaseous heat carrier. Due to the high temperature and oxidi2ing
medium (the stream of the gaseous heat carxi~r contained air
ox~gen), there took place pyrolysis of the heavy tar, par-
tial conversion of liquid organic compounds and combustion of
gas of the heat carrier. ~her termal decomposition of the heavy
tar resulted in the formation of a solid portion in the form
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1~17~49
o~ particles of coke. ~his being the case, the separated com-
bus~ibles partia]ly burnt, thereby raising -the temperature o~
the gaseous heat carrier to about 1200C.
Thus the heat carrier comprising products o~ thermal
processing of the fuel was delivered in~o the chamber 7 adap-
ted for -the second-stage heating, in which chamber the brow~
coal was heated by the obtained gaseous heat carrier to a
temperature o~ 500-800C at vJhich the coal was decomposed,
thus yieldin$ a vapour-and-gas suspension comprising a solid
product in the form of pulverized particles and a vapour and-
-gas mixture. The vapour--and-gas mixture (a portion) was di-
rected for purification and condensation to obtai~ gas, usa-
ble liquid products ~nd to separate low-grade products there-
from as heavy tars and pyrogenic water~ The low-grade pro-
ducts thus obtained were fed into the chamber II and 13 for
being processed therein. At the same time the obtained solid
product was discharged by a metering device 17 from chamber 7
adapted for the second-stage heating of brown coal.
Realisation of the proposed method, namely pyrolytic
processing of heavy tars and pyrogenic water gave 60-80% of
the solid product, i.e. 50 kg ~rom 75 kg o~ the h~avy tars.
The solid product having a calorific oapacity of about 8200-
8400 kcal/kg was deposited on the product of thermal process-
ing of the pulverized brown coal. So, the obtained product
comprises the product of thermal processing of the brown coal
and product of pyrolytic processing of the heavy tars. Since
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49
the calorific capacity of the first from the above-mentioned
products is about 6400-~700 kcal/kg and that oi the second
above-mentioned product is about 8200-8400 kcal/~g, the total
calorific capacity is abou~ 6930 kcal/kg, which is 230 kcaltkg
higher than that of the solid product obtained in a conven-
tional manner and having the calorific capacity of 6400-6700
kcal/kg. This results in increasing the solid portion by 18%.
Also, it is to be noted that the yield of solid product having
an increased calori~ic capacity is achieved withDut any in-
crease in the power consumption, i.e. due to the combustion
of combustibles which enter into the composition of low-grade
products.
Brown coal as the fuel for the process is taken for il-
lustration purpose~ only in this particular example. However,
it should be evident for those skilled in the art that any
other fuel can be used as the process material. With this in
view, and according to conventior.al re~uirements, prDcessing
of charge fuel as well as low-grade products is carried out at
temperature and time operating conditions being maintained in
a conventional manner~
.
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