US3918929A - Process for post-treating hot briquettes and the like - Google Patents

Process for post-treating hot briquettes and the like Download PDF

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Publication number
US3918929A
US3918929A US389052A US38905273A US3918929A US 3918929 A US3918929 A US 3918929A US 389052 A US389052 A US 389052A US 38905273 A US38905273 A US 38905273A US 3918929 A US3918929 A US 3918929A
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United States
Prior art keywords
briquettes
gases
air
temperature
hot
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Expired - Lifetime
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US389052A
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English (en)
Inventor
Paul Schmalfeld
Helmut Hahn
Joachim Lehmann
Kurt Kleisa
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GEA Group AG
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Metallgesellschaft AG
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Publication date
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
    • C10B53/08—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form in the form of briquettes, lumps and the like

Definitions

  • Briquettcs post-treated according to the invention have an optimum crushing strength and abrasion resistance making them easily transportable and useful in blast furnaces.
  • Hot briquettes are preferably made by pressing a mixture of caking coal and non-softening solids, partic ularly fine-grained coke, at temperatures in the plastic region of the caking coal.
  • the coke is heated to such a temperature that the mixture of coke and predried and possibly preheated caking coal has a mixed temperature in the range of 400 550C. and at this temperature is fed to a briquetting press.
  • the ratio of coke to caking coal varies widely in dependence on the nature and the caking capacity of the coal which is used and above all on the porosity and also the strength of the hot coke. Conventional ratios are 60-75% coke to 40-25% caking coal by weight.
  • the temperature of the mixture is preferably kept within the range of 4405 20C., particularly between 450 and 480C.
  • This is accomplished according to the invention by conveying hot briquettes through a shaft zone, countercurrent to oxygen-containing gases. In this operation, the presence of these gases, which preferably contain admixed air, results in a combustion of carbon on the surface of the briquettes and of the gases and tar vapors released by the briquettes when heated.
  • the combustion in the shaft is controlled in such a manner that the hot briquettes are heated to a certain temperature which is 50200C., preferably about 100C., above the briquetting temperature.
  • a certain temperature which is 50200C., preferably about 100C., above the briquetting temperature.
  • substantially all of the residual tar contained in the hot briquettes is removed and their content of volatile con stituents is reduced to or below 5% by weight.
  • the briquettes having this composition now posses the desired crushing strength and abrasion resistance.
  • An essential feature of the invention resides in admixing air at a controlled rate to gases which are recirculated through the shaft zone. As soon as the ignition temperature has been reached and the combustion temperature is sufficient to effect a higher temperature rise of the recirculated gases and of the hot briquettes, this air causes the combustion of the recirculated gases which flow through the briquette charge in the shaft zone and are subjected to a temperature rise.
  • the air is added to the recirculated gases at such a rate that the combustion on the surface of the hot briquettes or of the combustible components of the recirculated gases just results in the desired temperature. It will be desirable to admix the air to the recirculated gases before they enter the briquette charge. Alternatively, the air may be added through distributing means in the top half of the briquette charge where the recirculated gases and briquettes are at a higher temperature.
  • the hot mixture of coke and caking coal is pressed in a doubleroll press I to form hot briquettes.
  • the temperature of the mixture is in the range of 4005 50C., preferably between 450 and 480C.
  • the briquettes move by a horizontal conveyor 2 and a steep conveyor 3 to a feed chute 4, which delivers them into shaft zone 5.
  • the chute 4 is suitably provided with a grate or screen 6 for a removal of fines abraded from the briquettes and any undersize particles.
  • the briquettes move through the shaft zone 5 as a closed charge continuously from top to bottom.
  • the valve member 8 associated with the shaft is controlled so that the shaft is always entirely filled with briquettes up to the distributing chutes 7.
  • recirculated gases at a low temperature are fed into the shaft 5 through a conduit 9. These gases will be referred to hereinafter as recirculated gases.
  • the recirculated gases consist normally of the exhaust gases which have been formed as a result of the addition of air and the combustion and which still contain oxygen.
  • Water vapor from the means for the direct-contact cooling of the recirculated gases with water or from the means for the final cooling of the hot briquettes may be admixed to the recirculated gases.
  • Air flowing through the conduit 10 at a metered rate is admixed to the recirculated gases when they are at a temperature between 30 and 200C. before they enter the shaft 5 via conduit 9.
  • the mixture of recirculated gas and air flows from bottom to top through the hot briquette charge so that the latter is cooled in the lower portion 5a of the shaft while the countercurently flowing gases are heated.
  • the ignition temperature is reached and the air in the recirculated gases supports the combustion of carbon on the surface of the hot briquettes and the combustion of the gases and tar vapors which are released from the briquettes as they were heated.
  • the air is added to the recirculated gases at such a rate that the combustion results just in the desired temperature at the hot briquettes.
  • the hot briquettes may cool to, e.g., 420C. until they enter the shaft zone 5 and are then heated in the shaft to about 500C. by the partial combustion in the charge.
  • the temperature may be increased to 550600 or more if combustion air is added at a suitable rate. It is important to heat the briquettes to such an adjusted temperature that virtually all residual tar in the hot briquettes is eliminated and their content of volatile constituents is reduced below 5% by weight.
  • the combustion is slow and takes place in an extended zone (5b) of the briquette charge.
  • the recirculated gases which leave the shaft 5 at the upper end thereof always contain still a certain amount of unconsumed oxygen.
  • a number ofthermocouples (not shown) which are distributed in the shaft zone 5 over the height of the briquette charge and serve to monitor the cooling, combustion and temperature rise of the briquettes.
  • the temperature of the recirculated gases emerging from the briquettes charge also furnishes an indication of the temperature to which the hot briquettes have been heated.
  • the residence time of the hot briquettes which descend in the shaft 5 is generally -20 minutes in the heating zone 5b and about 20-40 minutes in the cooling zone 5a. In the case of a high temperature in the heating zone 5 b, a short residence time will be suffcient.
  • the success of the process is desirably checked by a determination of the contents of residual tar and volatile constituents in the treated hot briquettes.
  • the air rate may be controlled to ensure a suitable combus tion and a heating of the hot briquettes to the desired temperature in the top part of the briquette charge.
  • the recirculated gases which emerge from the briquette charge at the top end of the shaft zone 5 are fed by a conduit 11 into a cyclone zone 12, where the dust which has been entrained from the briquette charge is removed.
  • the gases are then cooled in a cooler 13 to a temperature between 30 and 200C
  • the cooler may be a waste heat boiler for the generation of steam, a water-evaporating spray cooler, or an indirectly cooled cooler using air or water.
  • the cooled recirculated gases and the admixed air are returned into the shaft 5 by a blower 14. Any surplus recirculated gas is withdrawn at 16.
  • the hot briquettes discharged from the shaft 5 at its discharge end 15 may be postcooled quickly to avoid selfignition, which might otherwise be possible.
  • This postcooling may be accomplished in various ways, e.g., by an aftertreatment with water, which may be sprayed or may be contained in dip basins, or by a mere air cooling.
  • the air conducted in the conduit 10 is admixed to the recirculated gases before they enter the briquette charge in the shaft 5.
  • the air may be added through distributing means in the top half of the shaft 5.
  • the distributing means consist, e.g., of a multiplicity of parallel horizontal tubes having uniformly spaced air outlet openings.
  • the air is fed to the tubes 20 through a supply conduit manifold 22.
  • the distributing tubes 20 may be disposed under downwardly open rooflike elements 21, which serve to stiffen the tubes 20 and also simultaneously to premix the air with the recirculated gases. This may be accomplished in the space under the roofs 21 outside the briquette charge. These distributing members may be used to provide over the height of the shaft a temperature profile which differs somewhat from that obtained when air is supplied through conduit 10.
  • the supply of air through the distributing tubes 20 may be combined with the admixing of air through the conduit 10.
  • the recirculated gases which emerge from the briquette charge through the conduit 11 still contain unburnt or undecomposed tar vapors which may form undesired deposits in the cyclone or cooler it will be suitable to admix air at a controlled rate to the recirculated gases before or after the cyclone in order to cause the combustion of these tar vapors and of any permanent gases which are still present. If this combustion is not sufficiently intense because the temperatures are too low, it will be suitable to admix not only air but to admix hot combustion gases and an excess of air so that the recirculated gases are sufficiently heated.
  • the process is applicable not only to hot briquettes which have been made at a temperature of 400550C. from a mixture of fine-grained coke and caking fine coal, but also to hot briquettes which have been made by pressing from coal or a coal mixture which has been heated to a temperature between 350450C. whereas hot coke has not been added.
  • the process is also applicable to the aftertreatment of hot pellets which have been made in a rotary drum from a mixture of hot, fine-grained coke with predried or preheated, caking fine coal with or without an addition of tar pitch.
  • Process for post-treating hot briquettes or similar shaped bodies containing caking coal which have been made at temperatures between about 350 and 550C, which comprises conveying the hot briquettes through a shaft zone countercurrent to oxygen-containing gases, thereby raising the temperature of said briquettes to from 50-200C above said shaping temperature by combustion within said shaft zone of carbon of the briquettes and of gases and tar released by the briquettes when so heated.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US389052A 1972-09-26 1973-08-16 Process for post-treating hot briquettes and the like Expired - Lifetime US3918929A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722247101 DE2247101A1 (de) 1972-09-26 1972-09-26 Verfahren zum nachbehandeln von heissbriketts oder dgl

Publications (1)

Publication Number Publication Date
US3918929A true US3918929A (en) 1975-11-11

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ID=5857379

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US389052A Expired - Lifetime US3918929A (en) 1972-09-26 1973-08-16 Process for post-treating hot briquettes and the like

Country Status (9)

Country Link
US (1) US3918929A (is")
JP (1) JPS5717040B2 (is")
BR (1) BR7307428D0 (is")
CA (1) CA994276A (is")
DE (1) DE2247101A1 (is")
FR (1) FR2200349B1 (is")
GB (1) GB1411496A (is")
IT (1) IT995483B (is")
ZA (1) ZA735185B (is")

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4248670A (en) * 1978-04-27 1981-02-03 Firma Carl Still Gmbh & Co. Kg Device for producing abrasion-proof coke forms
US4645513A (en) * 1982-10-20 1987-02-24 Idemitsu Kosan Company Limited Process for modification of coal
CN104053756A (zh) * 2012-02-24 2014-09-17 三菱重工业株式会社 改性煤制造设备

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2842425C2 (de) * 1978-09-29 1984-09-27 Carl Still Gmbh & Co Kg, 4350 Recklinghausen Vorrichtung zum Nachhärten von Heißbriketts

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3357896A (en) * 1966-01-25 1967-12-12 Stanley J Gasior Decaking of caking coals
US3384557A (en) * 1964-07-21 1968-05-21 Fmc Corp Method of curing of green briquettes by oxidation
US3663186A (en) * 1970-01-27 1972-05-16 Platon Nesterovich Dzhaparidze Method of producing metallurgical coke
US3674449A (en) * 1969-08-23 1972-07-04 Metallgesellschaft Ag Process of briquetting fine-grained cokes with caking coal in a plastic state

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3140985A (en) * 1959-09-26 1964-07-14 Metallgesellschaft Ag Method of oxidation hardening of briquettes
FR1472810A (fr) * 1966-03-29 1967-03-10 Coal Industry Patents Ltd Procédé de traitement thermique de briquettes à base de charbon carbonisé et briquettes ainsi obtenues

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3384557A (en) * 1964-07-21 1968-05-21 Fmc Corp Method of curing of green briquettes by oxidation
US3357896A (en) * 1966-01-25 1967-12-12 Stanley J Gasior Decaking of caking coals
US3674449A (en) * 1969-08-23 1972-07-04 Metallgesellschaft Ag Process of briquetting fine-grained cokes with caking coal in a plastic state
US3663186A (en) * 1970-01-27 1972-05-16 Platon Nesterovich Dzhaparidze Method of producing metallurgical coke

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4248670A (en) * 1978-04-27 1981-02-03 Firma Carl Still Gmbh & Co. Kg Device for producing abrasion-proof coke forms
US4645513A (en) * 1982-10-20 1987-02-24 Idemitsu Kosan Company Limited Process for modification of coal
CN104053756A (zh) * 2012-02-24 2014-09-17 三菱重工业株式会社 改性煤制造设备
CN104053756B (zh) * 2012-02-24 2016-04-20 三菱重工业株式会社 改性煤制造设备

Also Published As

Publication number Publication date
ZA735185B (en) 1974-07-31
FR2200349A1 (is") 1974-04-19
BR7307428D0 (pt) 1974-08-29
IT995483B (it) 1975-11-10
JPS4970803A (is") 1974-07-09
JPS5717040B2 (is") 1982-04-08
CA994276A (en) 1976-08-03
FR2200349B1 (is") 1978-12-08
DE2247101A1 (de) 1974-04-04
GB1411496A (en) 1975-10-29

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