WO2011026741A1

WO2011026741A1 - Use of a fuel in a self-sustaining pulsating oxygen-fuel combustion process

Info

Publication number: WO2011026741A1
Application number: PCT/EP2010/062191
Authority: WO
Inventors: Kirti Bhushan Mishra; Klaus-Dieter Wehrstedt
Original assignee: Bundesanstalt für Materialforschung und -Prüfung (BAM)
Priority date: 2009-09-03
Filing date: 2010-08-20
Publication date: 2011-03-10
Also published as: DE102009039893B4; DE102009039893A1

Abstract

The invention relates to the use of a fuel in a self-sustaining, pulsating oxygen-fuel combustion process, wherein the fuel comprises a compound selected from the group made of: a compound having the sum formula CnHn+3On-8, n ≥ 9, an organic peroxide, a compound having a pool flame comprising a Froude number that is 50 to 100 times greater than the Froude number of a pool flame of kerosene.

Description

Use of a fuel in a self-sustaining pulsating oxygen-fuel combustion process

The present invention relates to the use of a fuel in an industrial combustion process, particularly in a self-sustaining pulsatile oxygen-fuel combustion process.

Combustion is one of the most important chemical processes that humanity uses. Over time, therefore, are for the different applications of

Combustion processes each different fuels have been found or developed, which are optimized in their properties for the specific applications.

One of the main uses of combustion processes is heat generation, whether for industrial, electricity or heating purposes. Another important application of combustion processes is mobility, as currently the vast majority of vehicles are powered by internal combustion engines. In addition, combustion processes are also used to thermally recover waste or to make toxins harmless by means of combustion. The combustion processes used take place in a medium temperature range from 600 ° C to 1100 ° C.

Industrial combustion processes are often high-temperature processes that occur during the

Production of various materials are used. For example, in cement production, the raw meal is burned in a rotary kiln at temperatures of about 1450 ° C to form so-called clinker. In the sintering processes of ceramic production, temperatures of up to 2500 ° C are reached for some engineering ceramics. In furnaces also high temperatures are achieved. Thus, in glass production in the glass furnace temperatures around 1500 ° C can be reached, in metal furnaces, the

Process temperatures are still higher.

All combustion processes have in common that the resulting emissions, in particular NO _x , CO and tar are of concern for health and environmental aspects. It is therefore desirable to provide fuels or combustion processes in which such emissions are reduced. In view of the above, the present invention proposes the use of a fuel according to claims 1, 5, 6, 7 and 8. Further advantageous

Embodiments, details, aspects and features of the present invention will become apparent from the dependent claims, the description and the accompanying drawings. In the latter shows:

Fig. 1 shows the time course of the relative flame length of a tert-butyl peroxybenzoate pool flame.

According to a first embodiment, a fuel is used in a self-sustained pulsating oxygen-fuel combustion process comprising a compound selected from the group consisting of: a compound having the empirical formula C _n H _{n + 3} O _n _8, n> 9 , an organic peroxide and a compound whose pool flame has a Froude number which is 50 times to 100 times greater than the Froude number of a pool flame of kerosene. According to one embodiment of the invention, the compound may have the empirical formula CnH ₁₄ 0 ₃ , in particular, the compound may have tert-. According to another development of the invention, the organic peroxide may be a peroxyester, in particular tert-butyl peroxybenzoate (TBPB)

be. Organic peroxides, especially peroxyesters and including TBPB, are known as free radical initiators for the polymerization of various monomers. Use of this class of substance as fuel or fuel additive in self-sustaining pulsating

Oxygen-fuel combustion processes, however, the applicant is not known.

According to yet another embodiment, the pool flame of the compound has a Froude number that is 50 times to 100 times greater than the Froude number of a pool flame of kerosene. According to a further development, the Froude number may be 70 times to 80 times greater than the Froude number of kerosene. In particular, tert-butyl peroxybenzoate has a positive Number in this area. Here, under a pool fire, a generally turbulent diffusion flame whose liquid fuel is spread horizontally, understood. For example, pool fires are a type of frequent fire damage that can arise, for example, during storage, transport and processing of liquid fuels. The Froude number indicates the initial momentum of the flame, with Pool Frog being more likely to have small Froude numbers, since the flow rate is essentially due to the buoyancy of the combustion. Overall, the chemical and

Physical basics of pool fires well studied and will not be further elaborated here.

Fuels according to the embodiments described above and their

Further developments show a hitherto unknown and surprising burning behavior. Thus, FIG. 1 shows the time profile of the relative flame length of a pool flame of tert-butyl peroxybenzoate. The relative flame length is obtained as the ratio H / d of the flame length H to the diameter d of the fuel pool. At this time, the flame length H becomes the maximum visible length of the flame, i. in the wavelength range between 380 nm <λ <750 nm. Typical values for the relative flame length H / d of

Conventional fuels, such as liquefied natural gas (LNG) or kerosene, range between 0.8 and 4. On the other hand, Fig. 1 shows that over time the relative flame length H / d for tert-butyl peroxybenzoate can increase to 18. In other words, the tert-butyl peroxybenzoate flame has a relative flame length up to 18 times the pool diameter. However, the relative flame length of the tert-butyl peroxybenzoate pool flame also decreases to low levels of H / d -2. This variation in relative flame length is not uncommon per se and will apply to others

Fuels observed. However, the surprising thing about the fuels described here is firstly the large variation of the relative flame length by an order of magnitude and secondly the regularity of this variation. Thus, the fuel exhibits an approximately periodic pulsation of the relative flame length which, because of its appearance in the diagram (see Fig. 1), is also referred to as a "W effect." In other words, fuels of the type described exhibit a substantially regular time variation relative flame length for pool flames by a factor of 4 or more, which does not mean absolute regularity in terms of strict temporal periodicity, but similarity of respective time intervals of large or small relative flame length and similarity of respective increase or decrease in relative flame length between such time intervals. In this context, it should be noted that the frequency f of the pulsation is given by

where Fr _{f is} the Froude number of the pool flame of the fuel. Since the Froude number of fuels described is 50 times to 100 times greater than that of kerosene, their

Pulsation frequency f corresponding to 7 times to 10 times lower than that of kerosene. Furthermore, the burn rate of the fuels described herein is typically 80 to 120 times higher than that of kerosene.

The natural pulsation of the fuels described above can be used in combustion processes. For example, US Pat. No. 6,398,547 discloses a glass furnace in which a pulsating high-temperature combustion process takes place. The pulsation of the

Combustion process is generated via a specially designed valve. The valve controls the fuel supply to the burner, whereby the fuel rate can be controlled in an oscillating manner. The valve is connected to a computer-controlled control, which has a complex logic unit.

Instead, using the presently described fuels having natural pulsation behavior in high temperature industrial combustion processes, the benefits of pulsating combustion processes can be achieved without having to provide additional means such as pressure generators or complex injectors. This not only reduces costs but also allows more compact designs of the systems. With the aid of the fuels described herein, a more complete combustion and, in particular, a reduction of the pollutant emissions and the tar content in the exhaust gases can be achieved. In particular, by using the described fuels, the combustion efficiency can be increased on an industrial scale. Since the fuels described are carriers of active oxygen, which contributes to the combustion, they can ensure a stable combustion even without or with reduced external oxygen supply.

In particular, the use of these fuels in industrial high temperature processes is advantageous. These are called high-temperature processes considered in particular those combustion processes that occur at temperatures above 1200 ° C. High-temperature processes continue to include in particular such

Combustion processes that occur at temperatures above 1400 ° C, especially above 1500 ° C. Typically, such high-temperature processes take place in specially designed high-temperature furnaces, for example glass furnaces or rotary kilns.

The use of the described natural pulsation-type fuels is particularly useful in glassmaking, e.g. in a glass furnace, or in cement production, e.g. in a rotary kiln, or in ceramic production, e.g. in a sintering furnace, or for melting metals or other refractory materials, e.g. in a smelting furnace, advantageous. The fuels described not only provide the described natural pulsation of combustion in these processes, but also serve as strong combustion accelerators due to the presence of active oxygen in the molecule. In this way, the pollutant and tar content of the combustion products can be greatly reduced, and this at the same time simpler operation of the system, since additional means for generating the pulsation are not required. This also reduces the cost of such facilities. Furthermore, the external supply of an oxidant, for example air, oxygen or oxygen-enriched air, can be reduced.

The presently described fuels containing the described pulsating

Combustion behavior can also be present in a mixture with other fuels, in particular other liquid fuels. In particular, the fuels exhibiting the pulsating combustion behavior can be provided as a fuel additive in a proportion of 0.1% by weight to 80% by weight of the total weight of the fuel. According to a development, the stated fuels can be provided with a proportion of 0.1% by weight to 20% by weight of the total weight of the fuel. The exact proportion in the fuel depends on the specific use as long as combustion of the additive can be done safely. Thus, in some cases, a small amount may be sufficient to initiate the desired pulsating combustion behavior in the overall system, while in other cases a high level is required. In particular, the

Fuel completely consist of a fuel with pulsating combustion behavior. The present invention has been explained with reference to exemplary embodiments. These embodiments should by no means be construed as limiting the present invention.

Claims

Use of a fuel in a self-sustained pulsatile oxygen-fuel combustion process, said fuel comprising a compound selected from the group consisting of: a compound having the empirical formula C _n H _{n +} 30 _n -8, n> 9 organic peroxide, a compound whose pool flame has a Froude number that is 50 times to 100 times greater than the Froude number of a pool flame of kerosene.

2. Use according to claim 1, wherein the oxygen-fuel combustion process is a high-temperature process.

3. Use according to claim 2, wherein the oxygen-fuel combustion process takes place at temperatures above 1200 ° C.

4. Use according to one of the preceding claims, wherein the oxygen-fuel combustion process takes place in a high-temperature furnace.

Use of a fuel in glassmaking, wherein the fuel comprises a compound selected from the group consisting of: a compound having the molecular formula C _n H _{n + 3} O _n _8, n> 9, an organic peroxide, a compound whose pool flame has a Froude number which is 50 times to 100 times greater than the Froude number of a pool flame of kerosene.

Use of a fuel in cement production, said fuel comprising a compound selected from the group consisting of: a compound having the molecular formula C _n H _{n + 3} O _n _8, n> 9, an organic peroxide, a compound whose pool flame has a Froude number which is 50 times to 100 times greater than the Froude number of a pool flame of kerosene.

7. Use of a fuel in the manufacture of ceramics, wherein the fuel comprises a compound selected from the group consisting of: a compound having the empirical formula C _n H _{n +} O _n _g, n> 9, an organic peroxide, a Compound whose pool flame has a Froude number that is 50 times to 100 times greater than the Froude number of a pool flame of kerosene.

Use of a fuel for melting metals, said fuel comprising a compound selected from the group consisting of: a compound having the molecular formula C _n H _{n +} 30 _n _8, n> 9, an organic peroxide, a compound, whose pool flame has a Froude number which is 50 times to 100 times greater than the Froude number of a pool flame of kerosene.

Use according to any one of the preceding claims wherein the compound is a peroxyester.

Use according to any one of the preceding claims, wherein the Froude number of the compound is 70 times to 80 times greater than the Froude number of kerosene.

Use according to any one of the preceding claims wherein the compound comprises tert-butyl peroxybenzoate.

12. Use according to one of the preceding claims, wherein the compound is a fuel additive in a proportion of 0.1 wt .- to 80 wt .- of the fuel.

13. Use according to claim 12, wherein the compound with a fuel additive

in a proportion of 0.1% by weight to 20% by weight of the fuel.

14. Use according to one of the preceding claims, wherein the fuel consists of tert-butyl peroxybenzoate.