WO2006103043A1

WO2006103043A1 - Method and device for the carbonisation of coke with a high volatile content

Info

Publication number: WO2006103043A1
Application number: PCT/EP2006/002800
Authority: WO
Inventors: Ronald Kim
Original assignee: Uhde Gmbh
Priority date: 2005-04-01
Filing date: 2006-03-28
Publication date: 2006-10-05
Also published as: TW200641110A; AR054337A1; DE102005015301A1

Abstract

The invention relates to a method for producing coke in a carbonisation chamber of a coke oven of the non-recovery or heat-recovery type. According to said method, the coke oven is filled with a layer of coke, which is heated, stripping volatile coke constituents from the coke, said volatile constituents being partially oxidised by means of air that is hypostoichiometrically supplied above the coke bed. A combustion chamber for burning unburned, volatile coke constituents and the gases that are generated during the partial oxidation is situated below the carbonisation chamber, the latter containing lateral walls, in which channels are provided, said channels connecting the upper, coke-free section of the carbonisation chamber on the gas side to the combustion system below the carbonisation chamber. The volatile coke constituents that are partially oxidised above the coke layer pass through the channels into the combustion chamber that is situated below the carbonisation chamber. Both the carbonisation chamber and the combustion system comprise units for the limited supply of air. The combustion of the volatile coke constituents takes place only partially during the partial combustion with the aid of air, both in the carbonisation chamber above the coke bed and in the combustion system located below and a complete combustion is carried out subsequently in a separate afterburning system, which is situated outside both the coke chamber and the combustion system that lies below the coke chamber. Said system is preferably configured as a device with at least one inlet opening that is provided in the flue gas channels lying outside the coke oven, downstream of the latter, said opening permitting the admission of the air from the partial combustion.

Description

Method and device for coking coal with high

volatile content

The invention relates to a process for the coking of coal, especially those with high or varying volatility in coking plants with coking chambers after the non-recovery process or the heat recovery process, further a device with which this method can be operated very easily. The method presented here is independent of the number of coking ovens used, if they form a battery.

For coking the preheated coking chamber of the coking furnace is filled with a layer of carbon and then sealed. The carbon layer may be in bulk or in compacted, milled form. The heating of coal causes outgassing of the volatiles of the coal, especially hydrocarbons. Further heat generation in the coking chamber of non-recovery coking ovens and heat-recovery coking ovens occurs exclusively through the combustion of the released volatile carbon constituents, which gradually outgas due to the progressive warming.

According to the conventional art, the combustion is controlled so that a part of the released gas, which is also referred to as raw gas, burns in the coking chamber directly above the coal charge. The necessary combustion air is sucked in through openings in the doors and ceiling. This combustion stage is also referred to as 1st air stage or primary air stage. The primary air stage usually does not result in complete combustion. The heat released during combustion heats the carbon layer, forming an ash layer on its surface after a short time. This layer of ash ensures the exclusion of air and prevents the carbon layer from burning off in the further course of the coking process. Part of the heat released during combustion is transferred from the top, through the forming ash layer into the coal bed due to thermal radiation. Another part of the heat generated is transferred mainly by heat conduction through the bricked furnace walls in the carbon layer. However, a mere heating of the carbon layer from above using only a single air stage would lead to uneconomically high cooking times. Therefore, the partially burned in the primary air stage raw gas is burned in a further stage and the heat is supplied to the carbon layer from below or sideways. In particular, two technologies are known in the prior art: In US Pat. No. 4,124,450, US Pat. No. 4,045,299 and US Pat. No. 3,912,597 to the inventor describe how the hot mixture of combustion exhaust gas and partially combusted raw gas is channeled below the coking chamber it can give off some of its heat to the lining located under the carbon layer, which transmits the heat energy to the coal via heat conduction. In the further course of the flow, afterburning is carried out in a recuperatively operated combustion chamber arranged between the side walls of the coking chamber. The heat generated there is transferred sideways due to heat conduction via the furnace walls to the carbon layer, whereby the cooking times are significantly reduced. Such a combustion stage is also referred to as 2nd air stage or secondary air stage.

The other conventional technology performs the partially combusted in the primary air stage gas via channels in the furnace walls, which are also referred to as "downcomer", the heaters in the sole below the coking chamber, where still sufficient combustion air is sucked to a complete Burn - to reach. This also means that the coal charge heat is supplied both directly by heat radiation from above and indirectly by heat conduction from below and the coking rate and thus the throughput of the furnaces are significantly increased.

The resulting from the two-stage combustion in the furnace flue gases are then passed in the conventional state of the art located outside of the furnace flue gas ducts towards the chimney and there in the case of non-recovery process evacuated into the atmosphere or in the case of heat- Recovery process, for example, a unit for steam generation are supplied.

It has proved to be problematic that the release of the volatile carbon constituents does not proceed uniformly over the cooking time. At the beginning of coking, a decrease in the furnace chamber temperature is recorded. This is caused by the filling process, as the coal is filled at ambient temperature into the warm furnace chamber. This is followed by a period of stormy release of high calorific gas. The sudden supply of heat in the coking oven can by the Coal and the furnace building materials can only be absorbed at a limited speed. The temperature in the furnace chamber therefore increases in the course of the coking process and, in the case of a high proportion of volatile constituents of the feed coal mixture, may lead to an exceeding of the application boundary temperatures of the coking furnace building materials used or of the downstream flue gas ducts and subsystems.

Furthermore, due to the high temperatures also increase the harmful components in the flue gas, such as nitrogen oxides NO _x . Nitrogen oxides are formed in combustion processes where fossil fuels such as coal are burned. They are formed in the flame and the surrounding high-temperature zone by partial oxidation of the molecular nitrogen of the combustion air and the nitrogen chemically bound in the fuel. The majority of the oxides of nitrogen emitted by the furnace consists of thermally formed NO at high furnace temperatures.

In the course of the cooking time, the release of the volatile carbon components is then increasingly weaker again.

To avoid such problems and to ensure the most uniform heat generation and coke quality, a coal mixture is used in the coking oven, which is composed of several single carbon components together. The coal mixture is conventionally adjusted so that the volatile content is limited by a certain maximum value. Since a high proportion of coal available worldwide does not meet this criterion, this procedure limits the choice of coal that can be used for this coking process, which leads to economic disadvantages.

The object of the invention is therefore to provide an improved method which provides no more restrictions on the coal in terms of content of volatile components, leads to a reduction of nitrogen oxide pollution in the flue gas, the material of the coking oven protects and at the same time Improve coke quality without reducing specific coke throughput.

The invention solves the problem according to the main claim by.

The coking chamber is filled with a layer of coal,

The coal is heated and outgassing volatile carbon constituents from the coal, • these volatile carbon constituents are partially oxidized by means of substoichiometrically supplied air directly above the coal bed,

A combustion system for combustion of unburned, volatile carbon constituents and the gases produced in the partial oxidation is arranged below the coking chamber,

The coking chamber contains side walls in which channels are embedded,

These channels connect the upper, coke-free part of the coking chamber on the gas side with the combustion system below the coking chamber,

• the volatile carbon constituents partially oxidized above the coal layer pass through the channels into the combustion system below the coking chamber,

Both the coking chamber and the combustion system have means for limited supply of air,

• The combustion of the volatile carbon constituents by means of air both in the coking chamber above the coal bed and in the arranged below

Incineration system is initially incomplete as partial oxidation, and

Complete combustion is only subsequently carried out in a separate afterburning system which is located both outside the coking chamber and outside the combustion system located below the coking chamber.

It is not necessary to carry out this process over the entire cooking time of a coal charge. So it may make sense at the beginning of the heating phase as well as in the late decay phase to operate less than 3 stages simultaneously, at least as long as the outgassing of the volatile components is weak. Upon reaching a critical furnace chamber temperature, the method described above is successfully used for moderating. The fact that the secondary air stage is only operated as a partial oxidation, the heat generated thereby and thus the heat input from the bottom reduce in the coking chamber, which again slows the outgassing. The further reduction in the primary air stage additionally reduces the heat input from above.

Since the volatile constituents of the coal in this way can contribute somewhat to an overall high temperature level, the coking process as a whole runs longer at a high temperature level, which overall leads to a significant acceleration of the cooking process. The usually subsequent decay phase, in which only remains of less volatile constituents of coal must burn down significantly and equalizes the time spent by the coal charge at a high temperature level, which is an advantage of the invention. It is also advantageous that straight coal, which are considered inferior due to a particularly high proportion of volatile components, can be used here with profit as coking accelerator.

In one embodiment of the method it is provided that.

The partial oxidation in the coking chamber above the carbon layer is operated with a value of lambda between 0.4 to 0.7, preferably 0.5, the partial oxidation in the combustion system below the coking chamber with a value of lambda between 0.6 is operated to just below 1.0, preferably 0.9, and

• the post-combustion is operated stoichiometrically with a value of lambda between just above 1, 0 to 2.0, preferably 1, 7, wherein the value lambda denotes the ratio between the amount of air supplied and the amount of air required for a stoichiometric combustion.

In a further embodiment of the method it is provided that a regulation of the oxygen supply takes place at any time so that the furnace building materials are not exposed by any of the combustion stages of a temperature greater than 1400 ⁰ C. In practical terms, this can be achieved, for example, by using temperature measuring points at those locations of the lining where experience has shown that a lot of heat builds up, and by reducing the air supply when reaching certain temperatures which must be well below 1400 ^° C. in primary air stage and secondary air stage begins and observed the further temperature profile.

In a further embodiment of the method, it is provided that the heat produced during the afterburning is used to generate steam. By equalizing the coking process and the dissipated energy is available in a much more uniform manner. As a result, even plants with only a few coking ovens gain a time course of the waste heat accumulation, as it is possible in systems with a very large number of coking ovens, all of which work with a time offset and their individual characteristics would compensate each other, according to the conventional art. Thus, the use of waste heat as useful steam is much more economical than if the waste heat could be made available only abruptly for a short time, which is an advantage of the invention. Of course, other types of use for the waste heat are to be considered in individual cases.

The invention also includes an apparatus for carrying out the method. Afterburning in the sense of the method described above can generally be carried out in many different ways. The skilled person will consider a commercial combustion chamber, which is expensive. A further object of the invention is therefore to provide a particularly simple and cost-effective device which enables safe implementation of the method.

It is therefore provided to arrange at least one inlet opening in the outside of the coke oven, downstream of the flue gas ducts leading the flue gas to the chimney, can be supplied by the partial combustion air. The post-combustion then takes place in the flue gas duct by itself. The usual lengths are sufficient for a clean combustion safely. However, it must be ensured that the inlet opening is subsequently used in the flow direction of heat-resistant material. In contrast to the material which is used in the coking chambers, and which must have a good heat radiation characteristic, resistance to reducing atmosphere and good thermal conductivity and a good heat storage capacity and is therefore always limited in the selection, the use of heat-resistant material behind the air inlet opening in the flue gas duct no such restrictions and therefore easily and economically possible.

In one embodiment of this device, a metering device and a control member for changing the required amount of combustion air over the cooking time is provided at the air inlet opening in the flue gas duct.

The invention will be explained in more detail with reference to 3 sketches. Fig. 1 shows a sectional side view of a coking furnace and the left of it arranged afterburning in the supply line to the flue gas duct. Fig. 2 shows a plan view of the sol range, see Fig. 1 sectional plane AA ¹ , Fig. 3 shows a section of the front view, see Fig. 1 sectional plane BB '. The sectional side view in Fig. 1 corresponds to the sectional plane CC in Fig. 2. The sketches are not drawn to scale. The simple hatchings represent the area of the refractory lining, the irregularly crossed hatches the coal layer. In the Usually a large number of such ovens are arranged side by side and with a time delay in operation. Not drawn are also required for the operation of machinery and the necessary ways and facilities.

Fig. 1 shows in the right part of a conventional coke oven with a carbon layer 1, closed doors 2, the masonry dome 3, controllable air inlets 4 and 5 openings in the coking chamber 6, in which the raw gas from the carbon layer 1 outgass and partially burned (primary air step). The partially burned raw gas passes through the downcomers 7 in the secondary air stage 8. There, secondary air is added through the secondary air openings 9, followed at the place of addition, a second partial combustion, which is still performed stoichiometrically, and the carbon layer 1 from below by indirect Heat transfer heats.

The partially burnt exhaust gas leaves the coke oven through the feed duct 10. Shortly after leaving the coke oven, this combustion gas is supplied with further combustion air through the combustion air opening 11, whereby the afterburning according to the invention takes place in the feed duct 10. The flue gas obtained is passed through the flue gas duct 12 to the not shown chimney.

In the present example, afterburning and flue gas duct are arranged underground - the ground floor level 13 above it is needed for filling and emptying of the coke oven. Alternatively, however, an arrangement of the flue gas discharge via roof is possible. In such a case, the post-combustion can take place there. As an alternative to the example shown, in which the post-combustion takes place in the supply line to the flue gas duct, a central afterburning in the flue gas duct in front of the chimney in the context of the invention is possible and useful.

2 and 3 show the further views, it being understood that for the example shown, of course, the number of feeders for the air addition of the primary air stage and the secondary air stage as well as the arrangement of the channels can vary greatly without the subject matter of To leave invention. LIST OF REFERENCE NUMBERS

carbon film

doors

cathedral

air intakes

openings

coking chamber

downcomer

Secondary air stage

Secondary air ports

feed

Combustion air opening

Flue

ground level

Claims

claims

A process for the production of coke from coals (1) of high volatility in a coking chamber (6) of a coke oven of the "non-recovery type" or "heat recovery type" in which

• below the coking chamber (6) a combustion system (8, 9) for

Combustion of unburned, volatile coal components and the gases produced in the partial oxidation is arranged,

The coking chamber (6) contains side walls in which channels (7) are embedded,

These channels (7) connect the upper, coke-free part of the coking chamber on the gas side with the combustion system (8, 9) below the coking chamber, wherein • the coking chamber (6) is filled with a layer of coal (1),

The coal (1) is heated and outgassing volatile carbon constituents from the coal,

• these volatile carbon constituents are partially oxidized by means of substoichiometrically supplied air directly above the bed of coal, • the above the carbon layer (1) partially oxidized volatile carbon constituents via the channels (7) in the below the coking chamber located combustion system (8, 9), and

• both the coking chamber (6) and the combustion system have means (4, 5, 9) for the limited supply of air, • the combustion of volatile coal components by means of air in both the

Coking chamber (6) above the coal bed (1) and arranged below the combustion system (8, 9) is initially only partially incomplete as partial oxidation, and

A complete combustion is only subsequently carried out in a separate post-combustion system (11, 12) which is located both outside the coking chamber (6) and outside the combustion system (8, 9) arranged below the coking chamber (6).

2. The method according to claim 1, characterized in that • the partial oxidation in the coking chamber (6) above the carbon layer

(1) is operated with a value of lambda between 0.4 to 0.7, preferably 0.5, • the partial oxidation in the combustion system (8, 9) below the coking chamber (6) is operated with a value of lambda between 0.6 to just below 1, 0, preferably 0.9, and

• see the post-combustion overstoichiometric with a value of lambda between just above 1.0 to 2.0, preferably 1, 7, wherein the value lambda the ratio between the supplied air quantity and the amount of air required for a stoichiometric combustion.

3. The method according to any one of claims 1 or 2, characterized in that a regulation of the oxygen supply takes place at any time so that the furnace building materials are not exposed by any of the combustion stages of a temperature greater than 1400 ^C C.

4. The method according to any one of claims 1 to 3, characterized in that the heat generated during the afterburning is used to generate steam.

5. Apparatus for carrying out the method according to one of the preceding claims in a coking chamber (6) of a coke oven of the "non-recovery type" or "heat-recovery type" in which

• below the coking chamber (6) a combustion system (8, 9) for

The coking chamber contains side walls in which channels (7) are embedded,

• these channels connect the upper, coke-free part of the coking chamber (6) on the gas side with the combustion system (8, 9) below the coking chamber (6), characterized in that • in the downstream of the coke oven, downstream in the flow direction flue gas ducts (10) at least an inlet opening (11) is designed, which is designed so that it is suitable to pass part of the combustion air through them.

6. The device according to claim 5, characterized in that at the inlet opening (11) a metering device and a control member for changing the required amount of combustion air over the cooking time is provided.