GB2169310A

GB2169310A - Gas production

Info

Publication number: GB2169310A
Application number: GB08530942A
Authority: GB
Inventors: Lars Bentell; Goran Mathisson; Bjorn Hammarskog
Original assignee: SKF Steel Engineering AB
Current assignee: SKF Steel Engineering AB
Priority date: 1984-12-28
Filing date: 1985-12-16
Publication date: 1986-07-09
Also published as: DE3544792A1; FR2575488B1; SE8406649L; IT8523153A0; BE903938A; BR8506490A; SE446101B; CN85109363A; GB2169310B; JPS61185591A; FR2575488A1; IN166563B; AU5100785A; GB8530942D0; IT1200867B; SE8406649D0; DE3544792C2

Abstract

Gas mainly comprising CO and H2 is produced from finely divided carbonaceous starting material: Reactive coke is obtained from lumpy carbonaceous starting material, e.g. peat briquettes, in a carbonisation furnace (21); the coke produced is introduced into a carburation furnace (2) intended for the carburation of a gas mixture produced in a vaporization chamber (1) from the finely divided carbonaceous starting material; the volatile part of the carbonaceous material is introduced into said chamber (1) for cracking and reforming of its components. Hereby, a reactive coke is produced at the same rate as it is being consumed in the carburation, and no by-products from the coke production arise. <IMAGE>

Description

SPECIFICATION Gas production The present invention relates to a method for the prodution of a gas, mainly comprising CO and H2 from carbonaceous material, comprising vaporization and partial combustion of finely divided carbonaceous material with subsequent carburation of the gas mixture thus obtained in a coke-filled furnace, as well as to a device for the implementation of this method.

There are several different processes known in the prior artforthe production of reducing gases and synthesis gases of the type referred to herein, whereby the different methods usually produce different internal proportions of the CO and H2 in the gas. Furthermore, the known methods are limited in view of decreasing the contents of CO2 and H20 in the generated gas.

It is also known that a gas produced can be carburated by leading the gas through a coke-filled furnace. However, a disadvantage of this known method is that the coke is thereby responsible for about 10% of the total amount of carbon carriers consumed.

In order to carry out the carburation effectively at the desired low temperatures, reactive coke is required. It is of course known that reactive coke can be produced at low temperatures, which takes place in connection with extraction of tar. Great advantages are associated with the use of reactive coke as compared to the commercailly available coke; it emits neither smoke nor odour on combustion and it can be ignited at low temperatures, that is, around 600"C.

Due to the limited availability of reactive coke, one is today forced to use commercial metallurgic coke, which is however less reactive and therefore requires higher temperatures for carburation. This in its turn entails that the carburation reactions cease before the desired amount of CO and H2 has been obtained.

The object of the present invention is to obtain a process for the production of a gas mainlycompris- ing CO and H2 from arbitrary carbonaceous starting material, irrespective of its volatile composition, whereby the volatile portion present in the initial carbonaceous material can be utilized and also transformed into CO and H2, and whereby the physical heat present in the volatile portion and also partly in the coke, can be retrieved in the process.

A further object of the present invention is to produce reactive coke for utilization in the method for complete carburation of the gas produced in the process.

A further object of the present invention is to obtain a device for carrying out the process according to the invention.

This is attained by means of the present invention which is primarily characterized by carbonisation of carbonaceous starting material in lump-form in a furnace, with a supply of external energy and oxidant; feeding of reactive coke produced in the carbonisation furnace via a gastight lock system into the carburation furnace as required by the coke consumption therein for usage on carburation of the gas mixture obtained after vaporization and partial combustion; introduction of the hot gas obtained on carbonisation and comprising the volatile part of the carbonaceous starting material into the vaporization step for cracking and reforming of the therein included components as well as utilization of its physical heat content.

Preferably, the content of CO2 and H20 in the produced product gas is adjusted to between 0 - 10% and thereby the content of CO and H2 to between 100 -90%.

According to one embodiment of the invention, carbonisation of the initial carbonaceous material is carried out at temperatures between 600 - 800"C.

Hereby, an extremely reactive coke is obtained, and as the coke is fed directly into the connecting carburation furnace via a gastight lock system, it will never be exposed, for example, to atmospheric oxygen.

According to another embodiment of the invention, the lumps of carbonaceous material consists of anthracite, bituminous coal, lignite and/or peat.

According to a further embodiment of the invention, the production in the carbonisation furnace is controlled by means of level sondes in the carburation furnace. As the raw material used is arbitrary carbonaceous material, such as peat, a higher degree of coke consumption can be permitted in the carburation furnace if this would be required in spite of the use of reactive coke, for example to obtain a gas which is virtually composed of 100% CO and H2.

In the carbonisation furnace partial oxidation and carbonisation are carried out of the carbonaceous starting material with the simultaneous addition of external energy and oxidant.

According to another embodiment of the invention the oxidant is added in the form of a gas containing O2, H20 and/or CO2. The oxidant can thereby be totally or partially pre-heated before its admission to the carbonisation furnace, for which the leaving hot product gas can be utilized.

According to still another embodiment of the invention, the oxidant is supplied either totally or partlythrough a firing chamber containing an oil or gas fired burner, before it enters the carbonisation furnace. If gas is to be ignited in the burner, cooled and compressed product gas is used, which might be heat exchanged with the hot product gas before entering the burner.

According to still another embodiment of the invention the coke produced in the carbonisation furnace is cooled before leaving the carbonisation furnace. This can be done by the introduction of a cooled and compressed product gas into the discharge chamber of the carbonisation furnace. Alternatively, cooling can be accomplished by cooling of the discharge table.

Hereby, the coke becomes easier to handle in the gastight lock and further the choice of material for the lock system becomes less critical.

The invention also contains a device to carry out the method according to the invention, described in the introduction, consisting of a gas producing section with a vaporization chamber and a carburation furnace as well as a gastight supply unit for lumps of carbon carrier, and is primarily characterized by a carbonisation furnace connected with said carburation furnace via said gastight supply unit for lumps of carbon carrier, a supply unit for oxidant and energy, a discharge unit in the bottom of the furnace for the reactive coke produced as well as an upperoutletforthe coke oven gas produced on carbonisation.

According to one embodiment of the device according to the invention, it includes a supply unit for the cooling gas arranged to open into the discharge chamber of the carbonisation furnace which also contains the discharge device.

According to another embodiment of the invention, the device comprises a gas conduit from the gas outlet of the carbonisation furnace to the vaporization chamber. Hereby, the volatile part of the lumpy carbonaceous starting material is fed directly into the vaporization chamber for cracking and reforming.

According to a further embodiment of the device according to the invention, it comprises conduits for the supply of oxidant to the carbonisation furnace, comprising compressor means and heat exchange means for heat exchange with hot product gas.

According to a further embodiment of the device according to the invention, it contains a firing chamber in the conduit for the supply of the oxidant.

According to a further embodiment of the device according to the invention, an oil or gas fired burner is arranged in the firing chamber.

According to a further embodiment of the device according to the invention, it contains a conduit for the recirculation of product gas, comprising a cooling unit followed by a compressor, and this conduit opens into the burner. The conduit for recirculation might further contain a heat exchanger for the heat exchange of the cooled and compressed product gas with the hot product gas, when said conduit preferably also contains a by-pass unit so that the product gas freely, either totally or partly might be heat exchanged.

The invention will now be described in more detail with reference to the accompanying drawing, in which the figure shows a preferred embodiment of a plant for carrying outthe method according to the invention.

The gas producing section of the device comprises a vaporization unitwith a chamber referenced 1 for the vaporization and partial combustion of finely divided carbonaceous starting material as well as a carburation furnace referenced 2, filled with coke 3.

The vaporization chamber is preferably shaped as a cylindrical chamber with walls 4, 5. There can be several vaporization chambers connected to the carburation furnace. One or several slag outlets 6 are arranged for the discharge of slag from the carburation furnace and the vaporization chamber. The gas produced is removed through a gas outlet 7 in the upper section of the furnace.

Lumps of carbon carrier are supplied to the furnace via a gastight lock system 8 opening into the top of the furnace. The vaporization chamber 1 opens into the lower part of the furnace from where the gas passes up through the bed of coke and out through the gas outlet.

At least one burner is connected to the vaporization chamber, which in the shown version is comprised of a plasma generator 9. The plasma generator is connected to the vaporization chamber via a valve mechanism 10. Oxidant is introduced into the plasma generator by a supply conduit 11. The oxidant can be used as carrier gas, which is led through the plasma generator or alternatively, a separate carrier gas can be used. The hot, turbulent gas produced in the plasma generator is led into the vaporization chamber through the mouth 12 of the plasma generator. The carbonaceous fuel, preferably in powder form, is added through a supply conduit 13 into a concentric ring column 14 arranged around the mouth of the plasma generator and/or a lance 15, which can also be used for the supply of any required additives.

In the furnace, lances 16,17 are arranged forthe supply of any further oxidant such as for example H20, CO2, for the utilization of excess physical heat in the gas. Thus, this also provides the possibility for adjustment of the temperature and composition of the gas.

In the vaporization chamber close to the point of addition of coke, a first detection device 18 is arranged and in the gas outlet 7 from the furnace a second detection device 19 is arranged, for measurement of temperature and/or gas analysis and with the help of these two detection devices, the process can be controlled.

In the vaporization chamber 1 lances 20 are arranged for the supply of slag forming constituents.

The device also contains a carbonisation furnace 21 with a supply unit 22 for the lumpy carbonaceous starting material 23. Oxidant and external energy are supplied via a bustle-pipe 24 with tuyeres 25 which open into the furnace.

In the bottom of the furnace a discharge unit is arranged in the form of a rotating table 26 with a conduit 27, which is directly connected to the gas-tight lock system 8 for the addition of coke in lump form into the carburation furnace.

Oxidant in the form of 02, H20 and/or CO2 containing gas is supplied via a conduit 28 and a compressor 29 via the bustle-pipe 24 and tuyeres 25 to the carbonisation furnace. The oxidant can hereby be pre-heated, totally or partly, in a heat exchanger 30, using hot product gas via a conduit 31, which is directly connected to the product gas outlet 32.

External energy can be supplied by combustion of oil or gas.

If oil is used, the oil is combusted in a burner 33 which opens into a combustion chamber 34, whereby oxidant is either totally or partly supplied through the combustion chamber via a conduit 35. The oxidant can thereby be totally or partly pre-heated in the heat exchanger 30.

If gas used for the supply of external energy, some of the product gas produced is withdrawn via a conduit 36 and cooled in a cooling unit 37, after which the gas is compressed to the required pres sure in a compressor 38. From here, the gas can be totally or partly pre-heated in a heat exchanger 39, where the cold product is heat exchanged with the hot leaving product gas, which is supplied via a conduit 40. The product gas, thus cooled, compressed and if required, pre-heated, is then introduced through the burner 33 into the combustion chamber 34.

The coke produced in the carburation furnace might be cooled before removal from the furnace in order to facilitate the handling in the gastight lock.

This can be done according to one embodiment of the invention by feeding a partial flow of the cooled and compressed product gas into the discharge chamber 41 of the carbonisation furnace via a branch conduit 42 from the compressor 38.

The coke oven gas produced on carbonisation is fed from an outlet 43 at the top of the furnace, through a conduit 44to the vaporization chamber 1.

The gas exhibits hereby a temperature of between 500 - 700"C and contains the volatile part of the carbonaceous starting material. In this way, the energy is utilized at the same time as the components of the gas directly can be cracked and reformed in the vaporization chamber.

Thus, according to the invention, reactive coke for carburation is obtained in the required amount at the same time as the byproducts for the production of the reactive coke are transformed into valuable gas.

Usually, the finely divided carbon carrier which is added to the vaporization chamber constitutes about 85%, the circulated coke oven gas constitutes about 5% and the reactive coke in the carburation furnace constitutes about 10% of the produced product gas.

Further, the product gas usually contains about 20% H2 and about 80% CO but this proportion can be altered by for example, utilizing water vapour as oxidant in the combustion chamber.

Claims

1. A method for the production of a gas primarily composed of Co and H2 from a carbonaceous starting material, comprising the steps of vaporization and partial combustion of finely divided carbonaceous starting material with subsequent carburation of the obtained gas mixture in a cokefilled furnace, including carbonisation of carbonaceous starting material in lump form in a furnace while supplying external energy and oxidant; addition of reactive coke produced in the carbonisation furnace, via a gastight lock system into the carburation furnace depending on the consumption of coke therein, for the carburation of the gas mixture obtained after vaporization and partial combustion and introduction of the hot gas, produced on carbonisation and containing the volatile part of the carbonaceous starting material, into the vaporization step for cracking and reforming of the included components contained therein as well as utilization of its physical heat content.

2. Amethod according to Claim 1, wherein the amount of CO2 and H20 in the produced product gas is adjusted to between 0 - 10% and the content of CO and H2 is adjusted to between 100 - 90%.

3. A method according to Claim 1 or 2, wherein carbonisation of the carbonaceous starting material is carried out at a temperature of between 600 800"C.

4. A method according to any one of Claims 1 to 3, wherein the carbonaceous starting material consists of lumps of anthracite, bitumen containing coal, lignite and/or peat briquettes.

5. A method according to any one of Claims 1 to 4 wherein the process in the carbonisation step is controlled by means of level sondes in the carburation furnace.

6. A method according to any one of Claims 1 to 5, wherein oxidant in the form of a gas consisting of 02, H20 and/or CO2 is added to the carbonisation furnace.

7. A method according to Claim 6, wherein the oxidant is totally or partly pre-heated by heat exchange with hot product gas.

8. A method according to Claim 6 or 7, wherein the oxidant is totally or partly led through a combustion chamber containing an oil or gas fired burner, before being introduced into the carbonisation furnace.

9. A method according to Claim 8, wherein cooled and compressed product gas is used as gas in the burner.

10. A method according to Claim 9, wherein said cooled and compressed product gas is heat exchanged with hot product gas before entering the burner.

11. A method according to any one of Claims 1 to 10, wherein the coke produced in the carbonisation furnace is cooled before being removed from the furnace.

12. A method according to Claim 11, wherein a cooled and compressed part flow of the gas produced in the carburation furnace is used for the cooling of the coke.

13. A method according to Claim 11, wherein the coke is cooled by water-cooling of the coke discharge unit.

14. A device for the production of a gas containing primarily CO and H2 from carbonaceous starting material, with vaporization and partial combustion of finely divided carbonaceous starting material with subsequent carburation of the obtained gas mixture in a coke-filled furnace according to Claim 1, comprising a gas producing section having a vaporization chamber, a carburation furnace and a gastight supply unit for lumps of carbon carrier material; a carbonisation furnace connected to said carburation furnace via said gastight supply unit for lumps of carbon carrier material; a supply unit for oxidant and energy; a discharge unit at the bottom of the carbonisation furnace for the produced reactive coke; and an upper outlet for the coke oven gas produced by the carbonisation.

15. A device according to Claim 14, wherein the discharge unit of the carbonisation furnace compris es a discharge chamber, and wherein a cooling gas conduit opens into the discharge chamber.

16. A device according to Claim 14 or 15, includ ing a gas conduit from the gas outlet of the carbonisation furnace to the vaporization chamber.

17. A device according to Claim 14, including conduits for the supply of oxidant to the carbonisation furnace, said conduit comprising compressor means and heat exchange means for the exchange of heat with hot product gas.

18. A device according to Claim 17, including a combustion chamber situated in the conduit for the supply of the oxidant.

19. A device according to Claim 18, including an oil or gas fired burner arranged in the combustion chamber.

20. A device according to Claim 19, including a conduit for the recycling of product gas, containing a cooling unit and a subsequent compressor, which conduit opens into the burner.

21. A device according to claim 20, wherein the recycling conduit comprises a heat exchanger for the exchange of heat with hot product gas as well as a by-pass conduit past said heat exchanger.

22. A method for the production of gas, substantially as hereinbefore described with reference to the accompanying drawing.

23. A device for the production of a gas, substantially as hereinbefore described with reference to and as illustrated in, the accompanying drawing.