WO2010064025A1

WO2010064025A1 - Method, system and plant for treating process gasses, co generative thermal oxidizer

Info

Publication number: WO2010064025A1
Application number: PCT/GB2009/051534
Authority: WO
Inventors: Josephus Verboven
Original assignee: Fujifilm Manufacturing Europe Bv; Fujifilm Imaging Colorants Limited
Priority date: 2008-12-05
Filing date: 2009-11-13
Publication date: 2010-06-10

Abstract

The invention relates to a method of treating volatile compounds comprising the steps of providing a waste air-stream comprising volatile compounds from at least one process, for instance from an exhaust stream from a drying process, pre-heating said waste air-stream in a first heat-exchanger using rest heat from a separate process and igniting and incinerating said pre-heated waste air-stream in an incineration chamber forming a hot oxidized waste gas. The invention further relates to a system for carrying out said method.

Description

METHOD, SYSTEM AND PLANT FOR TREATING PROCESS GASSES, CO GENERATIVE THERMAL OXIDIZER

The present invention relates to a method, a system and a plant for treatment of process gases. More specifically, the invention relates to a method, a system and a plant for the treatment of volatile organic compounds containing waste air streams. Typically such waste air streams originate from drying processes, where ambient and/or preheated air is applied as a drying gas. Increasingly over the past half century, air quality has become an issue of public concern. Over this period, the understanding of the origins of the air pollution has steadily improved. A large part of this air pollution is attributable to the release of volatile organic compounds into the atmosphere. As a result, the reduction of the emissions of volatile organic compounds has become an increasingly important part of the overall strategy to improve air quality.

As described above, manufacturing sites can be responsible for a vast amount of volatile organic compound emissions annually. Solvent vaporization, for instance in drying processes or in some cases, hydrocarbon by products, are key to the manufacturing process of many of the items used regularly in daily life. The manufacture of familiar products thus results in the unavoidable production of considerable waste streams.

Due to environmental constraints, the release of these streams containing significant amounts of volatile organic compounds into the atmosphere is no longer an option. The control of volatile organic compound emissions has become essential to the environmentally friendly manufacture of these products. As a consequence, cost efficient treatment of these waste streams with a minimal environmental impact becomes indispensable in order to remain competitive.

In the industries many processes are used in which more or less volatile organic compounds are released into the air. In many cases this cannot be prevented by technical means and methods and arrangements have to be used to clean the air from these compounds. One process well known in the art is the use of incinerators. In this process the air including the organic compounds is burned.

The most common control method in use today is thermal oxidation, wherein the volatile organic compounds are incinerated and the heat produced by this incineration is recovered. WO89/57049 and US5, 810,581 are typical examples in which systems are described where by using a thermal oxidizer the air stream is preheated but it is not mentioned that the heat is generated in a separate process. In connection with this method, for reasons described above, the volatile solvent contents of the waste air stream adds up to amounts generally less than a few thousand parts per million. This waste air is then selectively collected and fed into a combustion chamber where it is mixed with sufficient natural gas to sustain combustion. It is then ignited in a large chamber that incinerates the volatile solvent, as well as the natural gas, thereby producing carbon dioxide and water vapor as the primary products of combustion.

Most of the time the amount of organic compounds in the air is not sufficient to maintain an oxidizing process and additional fossil fuels have to be burned to keep the process running. This way of treating the waste gas streams has the advantage, that there is no emission of organic compounds into the air. The disadvantage however is, that there is a significant carbon dioxide emission, which is a well known gas, responsible for the global warming, the so called green house effect. It is furthermore a well known fact, that the efficiency of the incinerator processes may range in order of 50% up to 95%. An improvement in the efficiency of the removal of organic compounds in the waste gasses could be to have the waste stream comprising air and organic compounds directly injected into the burner of a power generator such as gas turbine or motor package. It is however a well known fact, that the efficiency of such a combustion engine is dependant from the temperature of the air used. Using colder air of for example 4°C increases the efficiency significantly. However cooling the air might result in condensation of the organic compounds and possible other pollutants in the air, by which the system can get blocked. A further disadvantage of the present systems is the energy inefficiency, too much energy is lost, and the amount of carbon dioxide which is emitted. In US-A-5 832 713 an alternative system is described for the destruction of air streams containing volatile organic compounds, which comprises a power generator, a compressor, a combustor and a reaction chamber. A primary inlet to the combustor is provided for supplying a primary fuel to the combustor. As a secondary fuel, the volatile organic compounds contained in the waste air stream are used. Thus the waste air stream comprising at least one volatile organic compound is provided to combustor via a compressor.

One of the disadvantages of such a system is that the VOCs or other contained substances might condense in the piping, the appendages and/or the compressor. Furthermore, fossil fuels are used in this system, by which the VOCs can be effectively removed, on the cost of an increased carbon dioxide (CO2) exhaust, a gas which contributes significantly to the global warming.

Since the volatile compounds contained within these waste streams have the tendency to condensate, all the piping and appendages confronted with these streams need to be of special corrosion resistant materials. This renders these specific waste treatment relative complex and expensive.

Accordingly it is an object of the current invention to provide an alternative method and a system for the incineration of waste streams comprising volatile organic components.

Preferably, such an alternative method or system is flexible in the treatment of varying loads and compositions of the volatile organic compounds containing waste streams, wherein such method, system and plant is robust, low in maintenance and safe, while being able to guarantee the environmental requirements such as low volatile organic compounds (VOC), nitrogen oxides

(NOx) and carbon dioxide emission levels. A further object of the invention is to provide a method, a system and plant for an efficient removal of organic compounds from the exhaust streams of a process such as waste air- streams comprising volatile organic compounds with an efficient energy generation and a reduced amount of CO2 emission. At least one of these and/or other objects can be reached by the inventions described in the claims, e.g. a method according to claim 1, a system according to claim 14 or a plant according to claim 15.

Before describing the aspects of the invention in detail an explanation of an example of the flow in a possible of a process is given in reference to Fig.l.

Waste air-stream (09) can be a collection of waste air from at least one source of drying process/step (08);

Waste air stream (09) can pass a balancing box (12) where ambient air (ll) which is optionally temperature-controlled may be added and can be pre-heated via heat exchanger (13) using rest heat from an exhaust stream

(07) resulting in a pre-heated waste air-stream (14);

The pre-heated waste air- stream (14) can than pass a second heat exchanger (15) thereby increasing the temperature further resulting in a further heated waste stream (35); This further heated waste stream (35) can enter an incinerator chamber (16) of a recuperative combustor where it can be ignited and incinerated to a hot oxidized waste gas (19).

The hot oxidized waste gas (19) can pass the heat exchanger (15) giving its heat to the preheated waste air-stream (14) as described above and is leaving the heat exchanger (15) as a less hot oxidized waste gas flow (34). The rest heat of said less hot oxidized waste gas flow (34) can for example be used for steam/electricity transfer as depicted in numbers of processes upstream (20)-(33) (see Fig. l).

A first aspect of the invention is a method for treating organic volatile compounds comprising the steps of providing a waste air- stream comprising volatile organic compounds from at least one process, for instance an exhaust stream from a drying process! pre-heating said waste air-stream in a heat-exchanger using rest heat from a separate process and igniting and incinerating said pre-heated waste air- stream in an incineration chamber. In another embodiment of the invention said pre-heated waste air- stream (14) is heated in heat exchanger (15) with hot oxidized waste gas (19) before entering the incinerator chamber (16).

In further embodiments said rest heat is originating from a separate process as from a power pack or combustion engine (for instance from a gas turbine).

In still other embodiments the temperature of the incinerator chamber can be controlled between 700 and 1000°C and the minimum residence time of the organic compounds in the incinerator chamber can be controlled between 0.5 and 2 sec as a result of the design and operation of the flow of the waste air stream and the volume of the chamber. In another embodiment, using the method of this invention it is also possible to feed the incinerator chamber additionally with alternative fuels like liquid solvents and/or biogas.

This invention also relates to a system suitable for removing volatile organic compounds from a waste air stream comprising an incineration chamber and at least two heat exchangers, wherein a first inlet of a first heat exchanger is connected to a waste air stream comprising volatile organic compounds and said first inlet is linked to a first outlet of said first heat exchanger, a second inlet of the first heat exchanger is connected to an exhaust stream (07) from a power pack, a turbine engine, and/or another hot gas producing source and is linked to an outlet of the first heat exchanger, said first outlet of the first heat exchanger is connected to a first inlet of a second heat exchanger which is linked to a first outlet of the second heat exchanger and said first outlet of said second heat exchanger is connected to the inlet of the incineration chamber and the outlet of said incineration chamber is connected to the second inlet for said second heat exchanger.

The system can be equipped with a combustion engine for burning fossil fuels, wherein a heat exchanger can transfer the rest heat i.e. heat of the flue gas of the combustion engine to a waste air- stream comprising organic compounds.

A further aspect of the invention is an incinerator chamber capable of oxidizing the organic compounds of a heated waste stream (35) and capable of oxidizing alternate fuels at the same time.

Yet another aspect of the invention is a boiler producing steam using the heat of a less hot oxidized waste gas flow (34).

The invention can further comprise a steam turbine for using the generated steam from the boiler to produce electricity. In this case superheating of the steam fed to the steam turbine is required.

The arrangement may further comprise a selective catalytic reducer to treat a less hot oxidized waste gas flow.

Further advantageous aspects of the invention can be found in the dependent claims.

For a better understanding, other embodiments will be further elucidated by the following Figures 1 and 2, wherein: Fig. 1 is a schematic process flow diagram representing a method according to an embodiment of the invention! and

Fig. 2 is a schematic process flow representing the method according another embodiment of the invention. In the figures and the description the same or corresponding parts will have identical or similar reference signs. The embodiments shown should not be understood as limiting the invention in any way or form.

In figure 1 a waste air- stream (09) is collected from different sources (08). Typically the sources (08) from which the waste air stream is formed are produced in manufacturing processes which comprise drying steps. Examples of these processes (however not limited thereto) are coating processes where many solvents are used and removal of these solvents will result in waste streams loaded with volatile organic compound. Typical solvents used in these processes can be for instance acetone, ethanol, methanol, methylethylketone, l-methoxy2-propanol, gamma- butyrolactone, ethylacetate, isopropylalcohol, l-methyl-2-pyrrolidone.

The collected waste air- stream (09) is fed into a mixer, for example a balancing box (12), where additional air (ll) can be added. The additional air (ll) (optionally temperature controlled) can be added in order to maintain e.g. process temperatures and/or other process conditions at their respective set points without having to adapt the waste air- stream (09).

For safety reason a by-pass (lθ) can be provided for dispensing at least part of the stream in case e.g. of calamities occur in other process parts. The waste air stream, which can be conditioned in the balancing box

(12) enters a heat exchanger (13). In the heat exchanger (13) the waste air- stream (09) can be heated in a first step by rest heat of an exhaust stream (07). The exhaust stream (07) can for example originate from separate processes for example a power generation pack such as a gas motor, a gas turbine or the like.

As an example in figure 2, the power pack is depicted as a compressor turbine combination, wherein an air stream (θl) is compressed by a compressor (02), where after the air is mixed with a fuel in an enhanced pressure combustion chamber (04), which is fed with a fuel (03). After combustion the flue gasses are expanded over a turbine (05), of which a shaft is coupled to a generator (06). After exiting the turbine (05), the flue gasses of this power pack can typically be around 450"600⁰C and are fed to the heat exchanger (13). These turbines are for instance manufactured and/or supplied by OPRA Turbines in Hengelo (the Netherlands). Although a compressor turbine combination is shown in figure 2, different power generating systems may be applied, such as e.g. a fuel motor. Also other sources of hot gasses may be used in order to preheat the waste air stream (09).

The heat exchanger (13) applied in the process, can be a shell and tube type of gas-gas heat exchanger, a cross flow ceramic block heat exchanger, a triple switched structured ceramic heat exchanger and/or another type of heat exchanger. Suitable heat exchangers can be supplied by e.g. the EM group in Geleen (the Netherlands).

The pre-heated waste air-stream (14) leaves the heat exchanger (13) and enters a heat exchanger (15) of a recuperative combustor. A typical temperature of the pre-heated waste air stream at this stage is about 300- 500°C. The preheated waste air-stream (14) is heated up to a further heated waste stream (35) up to or just below the auto-ignition point temperature by using (recuperative) the heat from the hot oxidized waste gas (19) which is leaving the incinerator chamber (16).

This is advantageous in that only a minimal amount of additional fuel (18) and/or (17) is needed in order to have the further heated waste stream (35) ignited in the incinerator chamber (16) and have the volatile organic compounds contained therein combusted. A typical temperature to maintain combustion in the incinerator chamber and thus incinerate the volatile organic compounds, can be around 850"950⁰C. A much higher temperature can be undesirable since at higher combustion temperatures undesirable NO_x can be formed, whereas a much lower temperature can be undesirable as well, since no complete incineration of the organic compounds can be guaranteed. In order to have the volatile organic compounds completely incinerated a minimal residence time inside the combustion chamber (16) may be needed. A sufficient residence time can be about 0.5 seconds. A longer residence time may be set, although a residence time above 2 seconds can lead to considerable increased dimensions of the combustion chamber (16). So a practical residence time can be found as a trade off between on one side sufficient incineration and on the other side minimal combustion chamber volume.

Alternatively or additionally waste liquid solvents (17) from other processes might be used as alternative fuel in order to maintain incineration inside the incinerator chamber (19). Additional fuel might also originate from other sources such as for example bio-gas.

The less hot oxidized waste gas flow (34) leaving the recuperative heat exchanger (15) can be used to generate high pressure steam (23) in a boiler (21). Less hot gas can be understood as gas which has transferred heat to other gas in the heat exchanger (15). The steam (23), generated in the boiler (21), can be used for example to generate power by means of a back pressure steam turbine (24) and the generator (26). The steam (25) can additionally or alternatively further be fed into a low pressure steam system or be used to generate hot water.

In the boiler (21), an additional fired heater (20) can be installed. This fired heater can be fed with fossil fuels (18) and/or alternative fuels such as e.g. biogas. Boilers that can be applied in the process according to the invention can be supplied by the EM- group of Geleen (Holland) or Clayton (Belgium). In the boiler (21) a boiler feed water supply (22) is providing boiler feed water, which can originate e.g. from condensed steam or de-mineralized process water.

The waste oxidized gas stream exiting the boiler can be subjected to a selective catalytic reduction in reactor (27). In this process NO_x can be selectively removed by reducing it to N2. The remaining heat of the oxidized waste stream can be used for boiler feed water pre-heating and/or hot water generation, before being fed to a stack (33).

The exhaust stream (28) leaving the heat exchanger (13) can additionally be used for hot water generation in heat exchanger (30). Hereafter the exhaust (28) can also be fed to the stack (33). Optionally in case the NO_x contents of the exhaust as a gas is too high, this exhaust can also be fed to a selective catalytic reduction.

In another embodiment, the method for removing volatile organic compounds from a waste gas flow in general can comprise the following steps. Combustion of fossil fuel (03) in an internal combustion engine (04), the engine generating electricity and an exhaust stream (07) i.e. a hot flue gas, heating the waste air-stream flow (09) through the rest heat of the hot flue gas via a heat exchanger (13), giving a pre-heated waste air-stream (14) and an exhaust stream (28), feeding said pre-heated waste air-stream (14) through a second heat exchanger (15) resulting in a further heated waste stream (35) into an incinerator chamber (16), where the organic compounds optionally together with other fuels (17), (18) are oxidized after a minimum residence time, giving a hot oxidized waste gas (19), which is passing the heat exchanger (15) resulting in a less hot oxidized waste gas flow (34), using the less hot oxidized waste gas flow (34), optionally in combination with the heat of a fossil fuel burner (20) to generate steam (23) in a steam boiler (21), which optionally superheated steam (23) is used in a steam turbine (24) to generate electricity.

For the combustion of the fossil fuel (03) in the combustion engine (04), no special arrangements need to be considered, any combustion engine in the art can be used. The used fuel (03) can be any fuel known in the art, where in general natural gas gives good results. The air used may be the ambient air as such, compressed ambient air, cooled ambient air or compressed and cooled ambient air. From efficiency point of view compressed and cooled ambient air is preferably used. In this process, besides the electricity generated, an exhaust stream i.e. a hot flue gas is generated. Typical values for the temperature of the hot flue gas range from 450 to 650°C. The flow of the hot flue gas is dependant on the size of the total system and can be in a preferred embodiment 23 000 Normal m³/h (Normal conditions are at 0°C and 1 atmosphere), but one of the aspects of the invention is, that this hot flue gas is not used to directly heat up the waste air stream (09) comprising the organic compound to be oxidized. If this would be done the air flow in the recuperative combustor could be too high and the residence time of the organic compound in the recuperative combustor could be too short, which can result in incomplete break- down of the organic compounds. The rest heat (07) of the hot flue gas is heating up the waste air stream (09) via a heat exchanger (13).

In the heat exchanger (13), the hot flue gas is in an embodiment cooled to about 150-250°C. The exhaust stream (28) (i.e. the cooled, less hot flue gas) exiting the heat exchanger (13) can be used in an economizer (30) to generate hot water from 65-95°C.

Typically in drying processes of sources (08) a waste air- stream (09) comprising one or more organic compounds can be generated with a temperature ranging from 25-100°C. Optionally the waste air-stream (09) can be mixed with ambient air (ll) (optionally pre-heated in order to prevent condensation) before entering the heat exchanger (13). In the heat exchanger

(13) the waste air-stream (09), optionally diluted with ambient air (ll) is in an embodiment heated up to about 300"500⁰C. This pre-heated waste air-stream

(14) is now used in a recuperative combustor.

In a preferred embodiment the waste air-stream (14) flow rate is in the range of 20 000 to 30 000 Normal m³/h. As under-limit the waste air- stream can be 5 000 Normal m³/h. In principle, there is no upper-limit for the flow rate of the waste air-stream and the flow rates can be as high as 100 000 to 200 000 Normal m³/h or more. In such cases the sizes of the equipment such as the incinerator chamber (16), the heat exchanger (13) and the hot flue gas flow as well as the boiler (21) and the steam turbine (24) has to be adjusted in order to cope with these higher or lower flow amounts.

The recuperative combustor can be equipped with a heat exchanger (15) and incinerator chamber (16). In the heat exchanger (15) the pre-heated waste air-stream (14) is further heated for example to 600"800⁰C, after which it is fed to the incinerator chamber (16). In the incinerator chamber the temperature is controlled to 700-1000°C, preferably to 850"950⁰C.

In case the amount of volatile organic substances is too low to maintain the temperature of for example 900°C fossil fuels or alternative fuels, like biogas or organic solvents can be fed to the incinerator chamber. In an embodiment it is important that the residence time of the organic compounds is at least 0.5 sec. In case of a shorter residence time the decomposition and/or oxidation may not be complete, by which there will be still an emission of organic compounds. If the residence time is too long, the system may become inefficient. A residence time of 1 sec can also be used, or for example a residence time of 2 sec. The hot oxidized waste gas (19) leaving the incinerator chamber can be cooled in the heat exchanger (15) to about 550"650⁰C to a less hot oxidized waste gas flow (34) while heating the incoming pre-heated waste air-stream (14), as described above. In an aspect of the invention, the less hot oxidized waste gas flow

(34) having a temperature of about 600°C, can be used in a boiler (21) to generate steam (23). The water (22) used in the boiler (21) is preferably purified water or condensed water of the steam processes. The boiler (21) comprises an additional burner (20) in order to assure the production of steam (23) with a pressure of about 30-70 bar. This additional burner (20) can use fossil fuels (18), biogas or for example vaporized solvents. The steam (23) of for example 60 bar can be used in a steam turbine (24) in order to produce electricity. At the outlet of the steam turbine (24) the steam pressure is reduced to 3-30 bar, and can be used as utility steam (25) in production processes e.g. for process heaters. Next to that the high pressure steam (23) can be tapped in parallel before the inlet of the steam turbine in order to be used as high pressure steam for production processes e.g. for process heaters however in this way reducing the amount of steam to the steam turbine (24).

Before the less hot oxidized waste gas flow (34) is discharged to a stack this gas can still be used to generate, via an economizer (29), hot water with a temperature of 65-95°C. Furthermore, in order to have the gas emitted which fulfils all the environmental requirements a selective catalytic reducer (27) may be used, to further purify the waste gas.

The method as described results in the emission of clean gasses, furthermore the process results in a reduced emission of carbon dioxide, while it is a very efficient process for the generation of electricity.

One of the advantages of the present arrangement is that it can also operate without the waste air- stream (09). Just by changing the intake from waste gas air-stream (09) to ambient air (ll) which is comparable to a combined cycle combined heat and power plant, a very efficient energy production will occur, including the generation of electricity, hot water and steam, which can be used in the process for which the energy is used.

Another advantage of the present arrangement can be that the gain in less fuel intake (by minimizing the intake at fuel inlet (17) can be utilized as an extra fuel in-take amount at inlet (03) resulting in much higher efficiency in electricity and steam supply over the prior art.

This invention also relates to a system in which the method of the invention can be practiced. The system of the present invention is shown in the schematic diagram of figure 2. The system can for example be based on a conventional combined cycle heat and power plant for fossil fuel such as e.g. oil or gas. The system comprises an air intake (θl) to a compressor (02). From the compressor (02) the compressed air is passed through a combustion chamber (04) with a fuel intake (03). The combusted, hot gas form the burner (04) is passed through the turbine (05) in which it expands. This expansion is producing work, which is transferred to electricity in the generator (06).

The expanded gas or the flue gas from the gas turbine (05) as exhaust stream (07) will pass through a line with a temperature of about 500 to 650°C and supplied to the heat exchanger (13) in order to provide heat for the waste air-stream (09) from e.g. separate drying processes (08) or ambient air (11).

In case there is no process running, meaning there is no production of waste air-stream (09), the process air exhaust flow can also use the bypass (lθ) for the total system for balancing purposes or independent functioning. A balancing box (12) can determine the amount of outside air (ll) which has to be added to the waste air stream (09).

The output of the balancing box (12) will be passed to the heat exchanger (13) and can be heated up until approximately 350°C~450°C by means of the transfer of the flue gas. A resulting pre-heated waste air stream will be supplied to the heat exchanger (15) of the recuperative combustor ((15)+(16)) and can be heated up to 650°C~850°C resulting in a further heated waste stream (35) and supplied to the incinerator chamber where, for example by adding the fossil fuels (18), supported eventually by waste liquid solvents from other processes or alternate fuels (17), the temperature can be controlled to about 900°C and can be kept in a range of about 0.5 to 2 seconds where the further heated waste stream (35) is incinerated resulting in a hot oxidized waste gas (19) leaving the incinerator chamber. The specific temperature and residence time might depend on e.g. the requirements of the typical oxidation process and the type(s) and amount(s) specific volatile organic compound(s), contained in the waste air stream.

The hot oxidized waste gas (19) is fed to the heat exchanger (15) of the recuperative combustor where the temperature can be recuperative reduced to approximately 500°C~700°C resulting in a less hot oxidized waste gas flow (34), to the inlet of the waste gas boiler (21) in order to produce high pressure steam (23). In case more steam is required an additional burner (20), supplied by fossil fuel (18) or alternatives (17), can increase the heat for making more steam (23) and increase the pressure. Purified water and return condensate (22) can be used as feed water. The high pressure steam of e.g. 60 bar (23) can be used in a steam turbine (24) where again work can be produced for a generator (26) to produce electricity or used (partly) directly for high pressure process steam. The outlet (25) of the backpressure steam turbine (24) can be kept to 3-30 bar depending on process steam requirements. The steam (25) can for instance be used as utility steam for production process requirements e.g. process heaters.

In case required a SCR (Selective Catalytic Reducer) (27) can be installed to fulfill environmental requirements. The oxidized waste gas stream can be supplied to this selective catalytic reducer for further purification. An Economizer (29) can further optimize the system by the boiler feed water and/or making hot water (31) of for example 70-90°C before possible mixing in mixer (32) and feeding to the stack (33).

The exhaust stream (28) can have a temperature after the heat exchanger (13) of about 180°C which can also be used in an separate economizer (30) to produce hot water (31) of for example 70"90⁰C before mixing in mixer (32) with the oxidized gas output of the other economizer (29) and emission to the outside by means of the stack (33).

In order to inspect the emitted levels the stack can be provided with environmental measurement systems for e.g. NOx, SOx, VOC and other compounds. One of the advantages of the method and the system according to the invention can be that the incineration is no longer performed with a direct injection of fuel in the volatiles containing waste gas, but via a heat exchanger. Thus the fuel is first used for generating power, and thereafter its heat is used to indirectly heat up the volatiles containing waste air. Thus the waste air only needs minimal amounts of additional fuel to incinerate its volatiles completely. Thus a more efficient process is provided for, wherein more valuable heat and less valuable heat are used more efficiently from exergy point of view

It shall be obvious that the description of the various embodiments is directed both to plants and systems and to processes and methods to be performed therein. For example appropriate piping, connectors, valve assemblies and other appliances shall be used in such plants and systems, which will be obvious for the skilled person and are well within the scope of the present description. In the invention as described before numerous adaptations and modifications are possible. For instance the shafts of the generator 6 and the generator (26) can be connected as is the case in some combined cycle power generation systems.

The sources (08) can further include e.g. laboratory off gasses and or sewer vents off gasses which can typically also contain organic volatiles.

These and other adaptations and modifications are possible without departing from the spirit and scope of the invention.

Claims

1. A method of treating volatile compounds comprising the steps of: a) providing a waste air- stream comprising volatile compounds from at least one process, for instance from an exhaust stream from a drying process! b) pre-heating said waste air-stream in a first heat-exchanger using rest heat from a separate process! and c) igniting and incinerating said pre-heated waste air- stream in an incineration chamber forming a hot oxidized waste gas.

2. A method according claim 1 wherein said rest heat is generated from an exhaust stream originating from a power pack, an internal combustion engine and/or internal combustion turbine.

3. A method according to claim 1 or 2 wherein the pre-heated waste air- stream is further heated before entering the incinerator chamber with the hot oxidized waste gas exiting the incinerator chamber in a recuperative heat exchanger.

4. A method according to any one of the preceding claims, wherein the pre-heated waste air- stream, comprising volatile organic compounds, before entering the incineration chamber is heated just below its auto ignition point.

5. A method according to claim 3 comprising in addition^ d) generating high pressure steam in a boiler with rest heat of the less hot oxidized waste gas flow said waste gas flow exiting said recuperative heat- exchanger.

6. A method according to claim 1 wherein said incineration chamber is fed with additional fuel , chosen from fossil fuels, bio- gas, organic solvents and/or waste solvents.

7. The method according to claim 6, wherein high pressure steam is generated by an additional assisting fuel burner.

8. The method according to claim 6 or 7, wherein said high pressure steam is used for power generation in a steam turbine, like a back pressure steam turbine.

9. The method according to claim 6 wherein the temperature of the incineration chamber is controlled between 700 and 1000°C and/or a minimum residence time in the recuperative combustor is controlled between 0.5 and 2 seconds.

10. A system for removing volatile organic compounds from a waste air- stream comprising an incineration chamber and at least two heat exchangers, wherein a first inlet of a first heat exchanger is connected to a waste air- stream comprising volatile organic compounds and is linked to a first outlet of the first heat exchanger, a second inlet of the first heat exchanger is connected to an exhaust stream from a power pack, a turbine engine , and/or another hot gas producing source, said first outlet of the first heat exchanger is connected to an inlet of a second heat exchanger leading to the incineration chamber and the outlet of said incineration chamber is the second inlet for said second heat exchanger.

11. A system according to claim 10, wherein a recuperative heat exchanger is connected to the incineration chamber , which is able to heat the inlet pre-heated waste stream with the hot oxidized waste outlet gas of the incinerator chamber .

12. A system according to claim 10 or 11 further comprising a selective catalytic reducer in which the oxidized waste gas stream is purified.

13. A system according to any one of claims 10-12 wherein a recuperative combustor comprising the second heat exchanger and the incineration chamber is connected to a boiler for generating high pressure steam.

14 A system according to claim 13, wherein a steam outlet of the boiler is connected to a steam turbine for generating electricity.

15. A production plant comprising a system according to any one of the claims 10-14.