阅读说明：本技术 减少在材料热处理时的废气有害物质 (Reduction of exhaust gas pollutants during thermal treatment of materials ) 是由 蒂莫·施滕德尔 于 2018-12-17 设计创作，主要内容包括：本发明涉及一种用于减少材料热处理、尤其熟料制造的废气中的有害物质的方法,其中废气在进入除尘装置时具有大于或等于150℃的温度,本发明还涉及相应的设备,并涉及将引导通过磨机旁路的炉废气的热能量含量用于加热其它废气流,尤其加热从粗磨机中排出的废气的用途。(The invention relates to a method for reducing harmful substances in exhaust gases from the thermal treatment of materials, in particular the production of clinker, wherein the exhaust gases have a temperature of greater than or equal to 150 ℃ on entering a dust removal device, to a corresponding plant, and to the use of the thermal energy content of the furnace exhaust gases conducted through a mill bypass for heating other exhaust gas streams, in particular the exhaust gases from a roughing mill.)

1. Method for reducing harmful substances in exhaust gases of the heat treatment of materials, in particular of clinker manufacture, wherein the exhaust gases have a temperature of greater than or equal to 150 ℃ when they enter a dust removal device, characterized in that

a) Directing a portion of the furnace exhaust gases to the coarse mill and another portion of the furnace exhaust gases to bypass the coarse mill via a mill bypass, and

b) the exhaust gas from the coarse mill and the exhaust gas from the mill bypass are combined prior to the dust removal device,

and no further heating is required after the two exhaust streams are combined and before entering the zone for:

I) is used for catalyzing and denitrifying the nitrogen,

II) for the oxidation of CO and hydrocarbons, or

III) for catalytic denitrification and oxidation of CO and hydrocarbons.

2. The method according to claim 1, characterized in that the exhaust gas temperature is brought to a temperature higher than or equal to 150 ℃ in such a way that,

i) in a preheater, or

ii) increased fuel input in the preheater, calciner, furnace inlet and/or riser, or

iii) in the preheater, not only separation of fines but also increased fuel input.

3. The process according to claim 1 or 2, characterized in that said temperature is higher than or equal to 180 ℃, preferably higher than or equal to 200 ℃, more preferably higher than or equal to 240 ℃.

4. Method according to any one of claims 1 to 3, characterized in that the exhaust gas mixing in step b) is regulated by means of a control device, preferably by means of a cover and/or a slide.

5. Method according to any one of claims 1 to 4, characterized in that the operating temperature in the plant for clinker manufacture is additionally increased by fuel supply in the furnace inlet, the calciner and/or the riser.

6. A method according to any one of claims 1 to 5, characterized in that, for regulating the gas temperature before entering the dust removal device, a regenerative heat exchanger and/or a liquid-to-suction heat exchanger is additionally used.

7. Method according to any of claims 1 to 6, characterized in that a filter material with a heat resistance of 240 ℃ or higher, preferably selected from the group consisting of ceramic, PTFE and glass fibers, is used in the dust-catcher.

8. Method according to any one of claims 1 to 7, characterized in that the adjustment of the operating temperature is carried out depending on the heat requirement of the catalyst for the subsequent catalytic reaction, preferably denitrification.

9. Device for reducing the nitrogen oxide content or the CO and hydrocarbon content of furnace exhaust gases, in particular for carrying out the method according to any one of claims 1 to 8, characterized in that, seen in the respective flow direction of the exhaust gases,

a) after the preheater and/or the calciner, a device for dividing the exhaust gas flow is arranged, by means of which a part of the exhaust gas flow is conducted into the coarse grinding mill and another part of the exhaust gas flow is conducted past the coarse grinding mill,

b) a device is arranged downstream of the coarse grinding machine, by means of which the exhaust gas flow guided through the coarse grinding machine and the exhaust gas flow bypassing the coarse grinding machine are combined,

c) arranged after this device is a dust removal device, which operates at a temperature of greater than or equal to 160 ℃,

d) means for exhaust gases being arranged after said dust removal means

I) The catalytic denitrification is carried out, and the nitrogen is removed,

II) oxidation of CO and hydrocarbons, or

III) catalytic denitrification and oxidation of CO and hydrocarbons.

10. The apparatus of claim 9, further comprising

e) Means for feeding the feedstock to the preheater before the next-to-top stage, or

f) Means for increasing the fuel input in the preheater, calciner, furnace inlet and/or riser, or

g) Means for feeding the raw material into the preheater before the secondary top stage, and means for increasing the fuel input in the preheater, the calciner, the furnace inlet and/or the riser.

11. The apparatus according to claim 9 or 10, characterized in that said dedusting means operates at a temperature higher than or equal to 180 ℃, preferably higher than or equal to 200 ℃, more preferably higher than or equal to 240 ℃.

12. The apparatus according to any one of claims 9 to 11, characterized in that the apparatus comprises a control device for mixing the exhaust gases in step b), by means of which the two exhaust gas streams are regulated to be mixed with each other in such a proportion that the temperature setting is greater than or equal to 160 ℃, preferably greater than or equal to 180 ℃, more preferably greater than or equal to 200 ℃, still more preferably greater than or equal to 240 ℃, wherein the control is preferably carried out by means of a cover and/or a valve.

13. The apparatus according to any one of claims 9 to 12, characterized in that the apparatus additionally comprises a regenerative and/or reflux heat exchanger before the dust removal device.

14. Use of the thermal energy content of a furnace exhaust gas conducted through a mill bypass for heating a further exhaust gas stream, in particular the exhaust gas discharged from a coarse mill.

Technical Field

The invention relates to a method for reducing harmful substances in exhaust gases during the thermal treatment of materials, preferably the production of clinker, and to a corresponding device and use.

Background

Today, cement kilns are usually fired at high alternative fuel rates. This results in the exhaust gas temperature after the preheater rising to as high as above 400 c. Waste heat is typically used for material drying in a coarse mill. If the moisture content of the raw material is rather low, only a small amount of heat is actually required in the coarse mill. After the coarse mill, the exhaust gas temperature is typically below 100 ℃.

However, depending on the heat requirement in the coarse mill, this temperature is present only in a portion of the total exhaust gas. The other part (mill by-pass) can be cooled separately. The exhaust gas temperature in the downstream customary dust filter is then typically at 120 ℃ or slightly above 120 ℃. Furthermore, if there is excess heat, it is possible to quench the entire flue gas stream by the entry of water before entering the coarse mill. When the roughing mill is not operating, the exhaust gas stream is typically cooled in a cooling tower to a filter temperature low enough to avoid damage to the filter from excessive temperatures.

In the cement kiln, various harmful substances, such as nitrogen oxides (NOx), carbon monoxide (CO), and Hydrocarbons (HC), are inevitably generated or released. These harmful substances are reduced in the prior art by catalytic systems. To reduce nitrogen oxides, reducing agents are generally required. Ammonia is generally used for this purpose. To avoid deactivation of the ammonium sulfate formed depending on the concentration of sulfur oxides and ammonia and the operating temperature, a minimum operating temperature of greater than 180 ℃ is generally required. If the catalyst is located in the purge gas line after the dust filter, an additional temperature increase is therefore required in the prior art.

Since the formation of ammonium sulfate is reversible, it is necessary according to the prior art to heat at least temporarily to higher temperatures of, for example, 240 ℃, which leads to increased energy and operating costs.

Reference is made here, for example, to DE 102008013065 a1 or DE 102014108150 a1 as prior art.

The corresponding embodiments are also generally applicable to the thermal treatment of materials, i.e. in the thermal treatment of ores and similar materials.

Disclosure of Invention

The object of the present invention is to avoid the disadvantages of the prior art and to provide an improved apparatus and method for the heat treatment of materials, in particular for clinker manufacture. These should be distinguished in particular by a reduction in harmful substances and a more economical mode of operation.

These and other objects which will be apparent to the skilled person upon review of this specification are solved by the subject matter described below and in particular by the subject matter of the claims, wherein the dependent claims represent preferred embodiments.

Further preferred and advantageous embodiments are given in the following description.

Within the scope of the present invention, the expression "and/or" is meant to include not only the single elements associated with the expression but also combinations of single elements.

In the context of the present invention, the term "powder separation" means that the powder in the preheater is at least partially not transported before the last or uppermost cyclone stage, but at least partially before the second uppermost stage.

The subject of the invention is a method for reducing harmful substances in exhaust gases of the thermal treatment of materials, in particular the production of clinker, wherein the exhaust gases have a temperature of greater than or equal to 150 ℃ when they enter a dust removal device.

The invention also relates to a corresponding device.

The invention also relates to the use of the thermal energy content of the furnace exhaust gas guided by the mill bypass for heating other exhaust gas streams, in particular exhaust gases discharged from the roughing mill.

Detailed embodiments of the respective subject matter are given from the claims and the following description.

In order to be able to successfully achieve the catalytic reduction, it is within the scope of the invention to regulate the exhaust gas temperature upstream of the catalytic converter or upstream of the catalytic filter in such a way that a sufficient temperature for the discharge of ammonium sulfate is achieved at least temporarily.

In a preferred embodiment of the invention, the temperature entering the dust removal device is greater than or equal to 180 ℃, more preferably greater than or equal to 200 ℃, and particularly preferably greater than or equal to 240 ℃.

For this purpose, it is necessary to select a filter material having sufficient stability in the desired temperature range. It is therefore preferred within the scope of the invention to use a filter material in the dust removal device which has a heat resistance of 240 ℃ or more, preferably a filter material selected from the group consisting of ceramic, PTFE and glass fibers.

Furthermore, in a further embodiment, the exhaust gas temperature is preferably at least temporarily increased by fines separation in the preheater. Thus, the necessity of reheating the exhaust gas stream prior to catalytic reduction, i.e., catalytic denitrification, oxidation of CO and hydrocarbons, or a combination of both, is eliminated within the scope of the present invention.

In some preferred embodiments of the invention, the powder separation is carried out in direct operation without operation of the coarse mill, since higher temperature levels are already present here.

In some embodiments, the exhaust gas temperature may be increased by an installed combustion chamber, which is less preferred.

In some embodiments of the invention, the amount of fuel entering the preheater may be increased. In addition, in another embodiment of the present invention, an additional regenerative or reflux heat exchanger may be used.

In the design according to the invention, the separation of fines takes place therein, whereby the exhaust gas temperature is increased, since less heat is transferred to the fines.

Catalytic reduction in the context of the present invention means

I) The catalytic denitrification is carried out, and the nitrogen is removed,

II) oxidation of CO and hydrocarbons, or

III) catalytic denitrification and oxidation of CO and hydrocarbons.

Within the scope of the invention, the region for catalytic reduction, preferably catalytic denitrification, is connected to a dust removal device, preferably a filter adapted to the inlet temperature according to the invention, that is to say downstream of the exhaust gas, and comprises a device comprising a denitrification or oxidation catalyst.

In a particularly advantageous embodiment of the invention, the dust filter and the denitrification catalyst are combined with one another to form a catalytic filter.

In embodiments of the invention in which dust removal and catalytic reduction are combined in the form of a catalytic filter, advantageous effects are obtained, inter alia, by reducing the equipment expenditure.

For embodiments in which dust removal is combined with catalytic reduction, preferably catalytic denitrification, catalytic material is preferably added or applied to the filter. The combination of these two reduction stages is achieved by means of the measures according to the invention by adapting the operating temperature.

For embodiments in which the zone for catalytic reduction, preferably catalytic denitrification, is formed by separate dust filters and catalysts, but also for embodiments in which the zone for catalytic denitrification is formed by a combined catalytic filter, no further additional heating of the exhaust gas stream is required.

In a preferred embodiment of the invention, after the exhaust gas from the coarse mill and the exhaust gas from the mill bypass are combined, no further, additional heating of the exhaust gas stream takes place.

A decisive aspect of the invention is that the influence of the exhaust gas temperature not only precedes the catalytic converter for denitrification, but also significantly intervenes in the process. This significantly reduces the complexity of the device. Furthermore, the method can be better adjusted.

Within the scope of the invention, in various preferred embodiments, the fuel supply in the furnace system is increased by increased combustion in the hot zone (furnace inlet/calciner/riser). Hereby is achieved that the temperature level in the system and thus also the exhaust gas temperature rises.

The invention is based in particular on the use of other modes of operation; the mode of operation of the invention is based on heat supply by a furnace system, preferably by using powder separation and combustion.

The invention is also based in particular on the presence of a gas bypass at the mill; in this way, the exhaust gas temperature can be increased in the combined mode of operation.

Accordingly, in various embodiments of the present invention, the exhaust gas stream is not heated directly before the denitrification catalyst or the oxidation catalyst by a heat exchanger and/or a burner.

In various preferred embodiments of the present invention, no combustion unit, in particular no combustion device for power generation, is used or arranged after the mill drying and before the catalytic reduction, preferably catalytic denitrification.

In an optional embodiment of the invention, thermal conditioning is possible directly at the denitrification catalyst or the oxidation catalyst. This embodiment is less preferred.

The catalytic denitrification or denitrogenation reactions mentioned in the context of the present invention are the usual SCR (selective catalytic reduction) reactions known to the person skilled in the art.

Accordingly, for catalytic denitrification, it is within the scope of the present invention to use catalysts well known to those skilled in the art for SCR. Preferably, these catalysts are selected from vanadium, tungsten and titanium. Within the scope of this catalytic denitrification, it is likewise possible to meter in the customary reducing agents familiar to the person skilled in the art, preferably from the group consisting of ammonia, aqueous ammonia, urea and mixtures thereof.

The catalytic oxidation or oxidation of CO and hydrocarbons described in the context of the present invention is a common reaction well known to those skilled in the art.

Accordingly, for the catalytic oxidation of CO and hydrocarbons, catalysts familiar to the person skilled in the art for such reactions can be used within the scope of the present invention. Noble metal catalysts are preferably used.

Within the scope of the invention, in a preferred embodiment, the mixture of exhaust gases from the roughing mill and exhaust gases from the mill bypass can be regulated by a control device. In some preferred embodiments, this may be achieved by a lid and/or a slide.

In a further preferred embodiment of the invention, the adjustment of the operating temperature is carried out depending on the heat requirement of the catalyst for the catalytic reduction.

In other designs of the invention, desulfurization of the exhaust gas may be performed prior to catalytic treatment. This can be done, for example, with adsorbents such as slaked lime and sodium bicarbonate. These are injected into the exhaust gas, together with the SO in the exhaust gas₂And SO₃And (4) respectively reacting. The separation of the reaction products is at least partly carried out in a dust filter. The reaction products can also be incorporated into the product if, for example, slaked lime is applied directly to the preheater.

Various particular embodiments are shown below:

Drawings

The invention will now be further described by reference to the accompanying drawings. Here, like reference numerals denote like features. The figures are schematic and not to scale. Likewise, not all of the professionally customary equipment components are shown in the drawing; these are well known to those skilled in the art and are accordingly not described for reasons of clarity. The general representation of the drawings does not limit the invention in any way.

In the figures, the arrows indicate the direction of flow of the clinker-producing exhaust gases.

embodiment i. method for reducing harmful substances in exhaust gases of the thermal treatment of materials, in particular of clinker manufacture, wherein the exhaust gases have a temperature of greater than or equal to 150 ℃ when entering a dust removal device, characterized in that

a) Directing a portion of the furnace exhaust gases to the coarse mill and another portion of the furnace exhaust gases to bypass the coarse mill via a mill bypass, and

b) the exhaust gas from the coarse mill and the exhaust gas from the mill bypass are combined prior to the dust removal device,

and no further heating is required after the two exhaust streams are combined and before entering the zone for:

I) is used for catalyzing and denitrifying the nitrogen,

II) for the oxidation of CO and hydrocarbons, or

III) for catalytic denitrification and oxidation of CO and hydrocarbons

Or may be characterized in that it is,

a) directing a portion of the furnace exhaust gases to the coarse mill and another portion of the furnace exhaust gases to bypass the coarse mill via a mill bypass, and

b) the exhaust gas from the coarse mill and the exhaust gas from the mill bypass are combined prior to the dust removal device,

and no further heating after the two exhaust streams are combined and before entering the zone for:

I) is used for catalyzing and denitrifying the nitrogen,

II) for the oxidation of CO and hydrocarbons, or

III) for catalytic denitrification and oxidation of CO and hydrocarbons

Or may be characterized in that it is,

a) directing a portion of the furnace exhaust gases to the coarse mill and another portion of the furnace exhaust gases to bypass the coarse mill via a mill bypass, and

b) the exhaust gas from the coarse mill and the exhaust gas from the mill bypass are combined prior to the dust removal device,

and no heating is performed after the two exhaust gas streams are combined and between the dust removal device and the SCR zone.