FI128631B - Method for heat production in a power plant - Google Patents

Abstract

Process for the production of heat energy from a hydrocarbonaceous fuel. According to the process, the fuel is burned in an incineration plant at an elevated temperature, heat from the combustion is utilized and the soot particles are purified by catalytic exhaust combustion. According to the invention, fuel and air are fed into the exhaust gases to form a gas mixture and this is subjected to catalytic combustion at a temperature of over 600 ° C to reduce the oxides of nitrogen and to oxidize carbon monoxide, hydrocarbons and soot particles. The solution can be used for a significant reduction in NOx and CO and VOC emissions. The heat energy generated by the catalytic combustion process can also be used for heat production, whereby the feed of the fuel is divided between the combustion plant and the catalytic combustion process.

Description

The invention relates generally to the production of heat in boilers, gas turbines and diesel power plants and the like. The invention also relates to the reduction of exhaust emissions from power plants. In particular, the present invention relates to a method according to the preamble of claim 1 for generating thermal energy from a hydrocarbonaceous fuel. According to such a method, the fuel is combusted at an elevated temperature, the heat from the combustion is recovered and the combustion exhaust gases and the soot particles are purified by catalytic exhaust combustion. The invention also relates to a method according to the preamble of claim 18 for the catalytic purification of exhaust gases containing nitrogen oxides and carbon monoxide, hydrocarbons and soot particles from power plants using hydrocarbon-containing fuel.

Background Emissions of nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO) and hydrocarbons (VOC) from energy production are being limited worldwide to curb the greenhouse effect. In Europe, a number of directives have been adopted to this end for boilers, process equipment, fireplaces, etc. They set emission limits for greenhouse gases, either directly or through efficiency or emission limits. In the United States, EPA and CARB have set limits for nitrogen oxides and hydrocarbons, in part by compound. China is = going on a similar development. In Beijing, for example, the NOx limit value for boilers has been set at N 25 - 30 mg / m 'and CO at 80 mg / m'. The limits are so strict that they cannot be achieved with current conventional thermal incinerators without after-treatment. The same sharply tightening trend will continue in other industrialized regions of China. i N Even before the above-mentioned emission limits had stabilized, Beijing had set a target of 30 - to tighten even more. For NOx, the target is zero or almost zero emissions and N CO is well below the previous limit.

Instead of flue gas aftertreatment, commercial UltraLow NO and NoNO burner manufacturers use flue gas recirculation, water emulsions and gas preheating in their burners that efficiently mix the above techniques. Despite the name of the NoNO burner, no manufacturer of the thermal burner has achieved zero NO emissions. The lowest value found in the reports is 6 ppm with an Ox concentration of 3%.

Another option is flue gas cleaning. Selective catalytic and non-catalytic reducing agents (Selective Catalytic Reduction, hereinafter abbreviated as “SCR”, and Selective Non-Catalytic Reduction, “SNCR”) are commonly used to remove nitrogen oxides.

At its best, catalytic SCR achieves a purification rate of greater than 90% at a temperature of about 350 ° C. In its reports, the EPA reports an average NOx conversion of SCR of 85

20. Non-catalytic SNCR equipment achieves about 20% lower cleaning efficiency. Their use has been targeted at diesel vehicles.

- However, SCR equipment requires a separate reducing agent, urea or ammonia and their dosing equipment, which incurs significant investment and operating costs. Urea decomposes in the catalyst into ammonia (NH3) and carbon monoxide (CO). Ammonia and urea are transported and stored as aqueous solutions. The ammonia content is 27% and the urea content is 32%. Ammonia is a very toxic gas. NOy emission level to be achieved at the SCR plant - hence 7-30 ppm. In addition, CO emission limits require a separate oxidation catalyst. The use of ammonia as a reducing agent is based on its ability to selectively reduce NOx in a lean gas mixture.

= The high cost of SCR technology is due to the N 25 ammonia (NF3) or urea required for selective reduction in addition to the reducing agent and expensive storage, dosing, heat transfer and reduction equipment. In addition, the need for replacement of the SCR catalyst has been estimated by the EPA for 3 to 7 years. In SRC catalysts, the most common active substance, i.e. the catalyst, is vanadium pentoxy-E di (V, Os), which is more sensitive to poisoning than precious metals. The SCR catalyst is large in size N because of its low turnover, namely 10,000-20.00001 / h. Precious metal catalyst 30 - with lysers the change is 5. 10 times larger, ie the size of the precious metal catalyst is N about one-fifth to one-tenth of the SCR catalyst.

Other weaknesses of the SCR catalyst include NH3 leaks (2-5 ppm) and the risks of NH3 toxicity during handling and transport. Replacement of the mainly used toxic SCR catalyst (V, Os) with, for example, non-toxic zeolites is required, especially in the USA.

In addition, the limitations of catalytic combustion are the so-called catalyst toxins which must not be contained in the exhaust gas. The most important of these are organosilicon, heavy metal and phosphorus compounds. They permanently deactivate the catalysts. Sulfur compounds do not damage the platinum-activated catalyst, but the sulfuric acid formed as a result of the reactions can be concentrated on the surfaces of the heat exchanger at temperatures slightly above 100 ° C, causing corrosion.

DESCRIPTION OF THE INVENTION The object of the present invention is to eliminate at least some of the problems associated with the prior art and to provide a completely new solution for catalytic purification of exhaust gases containing nitrogen oxides and carbon monoxide, hydrocarbons and soot particles from hydrocarbon fuel plants.

- In the first embodiment of the invention, thermal energy is produced in two units, in which case thermal energy is first produced in the power plant by burning a hydrocarbonaceous fuel. Heat is recovered, for example, in a heat exchanger. The exhaust gases from the combustion are fed with fuel and air to form a gas mixture, and the gas mixture thus obtained is subjected to catalytic combustion, which is carried out at a high temperature. By carrying out the combustion in the presence of a catalyst under reducing and oxidizing conditions, respectively = at a temperature of at least 600 ° C, the nitrogen oxides contained in the flue gases are reduced 7 and the carbon monoxide, hydrocarbons and soot particles are oxidized. The heat E from the catalytic combustion is also recovered.

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N © 30 - In another embodiment of the invention, the exhaust gases of the energy plant are led to an exhaust gas burner N, where the gases are subjected to catalytic oxidation and reduction to reduce the NOx, CO, VOC and particulate concentrations of the exhaust gases and simultaneously produce thermal energy.

More specifically, the solution according to the invention is mainly characterized by what is set forth in the characterizing parts of the independent claims. The present invention provides significant advantages. As stated above, neither thermal combustion nor current flue gas cleaning methods make it possible to produce the pure thermal energy that is already being demanded in Beijing. However, the object can be achieved with the solution according to the present invention, in which the NOx, VOC, CO and particulate emissions of the exhaust gases of already operating boilers, diesel and gas turbine power plants can be reduced to near zero even with the catalytic exhaust burner. At the same time, small soot particles produced by oil and gas boilers and diesel power plants can also be burned.

Thus, with the present solution, NOx compounds can be reduced to a residual content of less than 1 ppm, and CO and VOC compounds can be oxidized to a residual content of less than 2 ppm. Small soot particles can also be burned in an exhaust gas burner at a temperature of 600 ° C or above. The most preferred operating temperature range for the burner is 850-1000 ° C. In this area, soot particles also burn quickly.

Simultaneous energy production is made possible by the use of flue gas from a thermal boiler, turbine or diesel power plant, etc. as a cooling and heat transfer medium in catalytic combustion. In this case, the inert thermal mass of the exhaust or flue gases is utilized in combustion = temperature control and heat transfer. The flue gas can be used to keep the temperature within the desired range of N 25 - preferably between 850 and 1000 ° C.

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O 7 With the present solution, which differs from other cleaning methods, it is possible to increase the thermal energy production capacity of the thermal boiler E by up to 60%.

N The exhaust gas burner can be added to all energy production equipment with low sulfur emissions and particulate emissions and without so-called catalyst poisons. In contrast, the amount of NOx, CO and VOC emissions from N energy sources is practically irrelevant. The afterburner also burns small soot particles produced by, for example, oil boilers and diesel power plants. If there is no storage POC catalyst or filter in connection with the catalysts, it is advantageous to provide an intermediate space before the heat recovery piping, in which the particles have time to burn before the energy is recovered. The exhaust burner can also be used to solve the emissions of older polluting 5 - even the smallest energy production equipment in use to the level of new, more stringent requirements. In principle, an exhaust gas burner can be used to clean all types of gases containing NOx, CO and VOC emissions by connecting the burner to a boiler or heat exchanger, as the catalytic combustion operates below the LEL limit. In this case, there is no similar safety risk - as in thermal combustion boilers, where accidents involving fatal injuries have occurred during the combustion of VOCs.

As the amount of gaseous emissions, especially the amount of gaseous emissions, is of little importance for the operation and cleaning result of the exhaust burner, freedoms can be allowed for the control of the primary energy source - and the choice of equipment. Boilers do not require expensive lowNOx or ultralowNOx burners and the air to fuel ratio can be optimized for maximum power. Diesel engines do not require exhaust gas recirculation (EGR) or very lean blend ratios to reduce NOx emissions, etc.

The exhaust burner is suitable for e.g. operating energy plants that do not meet the emission requirements of ever-tightening standards. Investments to reduce emissions are often worthwhile because plants are long-lived and require large investments. Another target is new plants.

© &. . . <. & 25 - In the following, the present technology will be examined in more detail by means of a detailed explanation with reference to the accompanying drawings.

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I E Fig. 1 shows a process diagram of one embodiment, N Fig. 2 shows a process diagram of a second embodiment, o 30 - Fig. 3 shows a process diagram of a third embodiment, and N Fig. 4 shows a process diagram of a fourth embodiment. In the present context, “energy plant? in particular a combustion plant producing thermal energy, living thermal energy, in which energy is produced from hydrocarbon-containing fuel by means of boilers, diesel turbines or gas turbines. 'Carbonaceous fuel' in the first application means a fuel which - contains, but is not necessarily limited to, organic compounds of carbon and possibly hydrogen, such as hydrocarbons. In addition to hydrocarbons, the fuel may contain oxygen-containing compounds such as ethers, esters and alcohols. Examples of carbonaceous fuels according to the first application are fuels derived from fossil fuels, such as oils, petrol, diesel and natural gas.

"Carbonaceous fuel" in another embodiment further means a fuel containing carbon compounds consisting primarily of alcohol (hydroxy) groups, ether groups or ester groups, or combinations thereof, for example, hydrocarbon compounds substituted with these groups. These fuels include various biofuels produced from biomass, such as lignocellulose, vegetable oils and animal fats, crops. The terms 'CO' and 'VOC emissions' and 'NOx emissions' and 'soot particulate emissions', respectively, refer to CO -, VOC and Nox gases and the soot particles (as mass) of the exhaust gases, respectively.

The present technology generally provides a solution for treating exhaust gases and generating energy with a catalytic exhaust burner. The method can be applied to both heat generation and exhaust gas cleaning, as described in more detail below. 3 25 5 In the process, additional air and fuel are fed to the exhaust gas generated by thermal combustion to produce the gas mixture required for catalytic combustion, after which the gas mixture is introduced into a catalytic combustion zone for combustion. The heat from combustion N is recovered. As a result of combustion, emissions of CO, VOC, NOx and soot particles are significantly reduced in the exhaust gases from catalytic combustion.

N In one application, the exhaust gases, fuel and air are mixed evenly to produce a homogeneous gas mixture.

In this application, additional air and fuel can be supplied to the exhaust gas burner and their supply is controlled by post-catalyst temperature and linear oxygen sensors according to the need for the air / fuel ratio required by each catalyst.

In order for the reactions described below to take place, enough fuel is preferably added to the exhaust gas to achieve a rich or stoichiometric mixture ratio. In the former, only the reduction of NOx to nitrogen (N;) and oxygen (O;) takes place, and in the latter, in addition, the oxidation of CO and VOC to carbon dioxide (CO;) and water (HO) also takes place.

When supplying the rich mixture, a second catalyst is preferably used, in which case it is provided with the additional air supply required by the lean mixture. Separate oxidation and reduction steps achieve the best results.

- When you want to produce the maximum amount of clean energy, you must inject not only fuel but also air into the flue gas. In order to prevent the formation of nitrogen oxides in the afterburning, the temperature should preferably be limited to about 1000 ° C. With this solution, which differs from other cleaning methods, it is possible to increase the thermal energy production capacity of the thermal boiler by up to 60%, as described in more detail below.

In one application, the exhaust gases, fuel, and air are mixed together in nested perforated supply lines and in a static mixer to form a uniformly mixed gas mixture.

The homogeneity of the gas mixture can be ensured with a static mixer, which is particularly advantageous in order to ensure even combustion.

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I E In one embodiment, the catalytic combustion is performed under reducing and oxidizing conditions, respectively, in one or more steps.

o 30 N In one application, the gas mixture is subjected to catalytic combustion in a three-way catalyst to an oxidation and reduction catalyst. In this case, the gas mixture can be burned, for example, in a three-way catalytic converter with a stoichiometric oxygen / additional fuel ratio in a combustion plant.

for the oxidation of unburned CO and VOCs and for the reduction of NOx emissions and for the oxidation of soot particles. When incinerated at temperatures above 600 ° C, the soot particles burn at the same time.

Alternatively, in a two-part catalyst, in the reduction section, the rich mixture reduces NOx emissions to nitrogen (N>) and oxygen (O) and oxidizes most of the CO and VOC emissions to carbon dioxide (CO) and water (HO).

- Then, with additional air, the gas mixture is made lean and then the mixture passes through an oxidation catalyst. It oxidizes the remaining CO and VOC emissions. In the next heat transfer step, the heat energy generated is utilized in water, for example by means of welded finned tube radiators, after which the exhaust gas leaves the boiler into the chimney, if necessary with the aid of a suction fan.

In one application, the gas mixture is first combusted in an oxidation and reduction catalyst with a rich supplemental fuel / oxygen mixture to reduce nitrogen oxides and a lean supplemental fuel / oxygen mixture to oxidize CO and VOCs and soot particles.

The reaction chain in reducing noble metal catalysts passes mainly through steam reforming and water gas transfer reactions: HO + HC -> H, + CO and H, O + CO -> H, + CO, 00 g & 25 and further o H, + NO, -> N, + HO .

O = - Some of the reactions are direct oxidation and reduction reactions.

N> © 30 Catalytic combustion takes place below the lower explosion limit (LEL) at all times. Burning-

O N substance can often be the same as in the primary energy generating device.

If the flue gas temperature before catalytic afterburning drops below 250 ° C and the fuel is natural gas or other high temperature fuel, then the catalyst structure should be recuperative or regenerative. The metal cross-flow catalyst, for example, should be used to maintain combustion. low temperature flammable fuel such as methanol or ethanol. as a support fuel. The catalysts used in the combustion are preferably coated with stable metal oxides, in particular an oxide having a cation of Al, Ce, Zr, L or Ba, to which noble metals - such as Pd, Pt, Rh or mixed oxides of these parent metals - have been attached. These noble metal catalysts are non-toxic and do not produce toxic compounds in the reactions as in conventional SCR catalysts. The temperature in the catalyst is at least 600 ° C, especially 850-1000 ° C under reducing conditions or under both reducing and oxidizing conditions. Most preferably, in a three-way catalyst, the exchange is maintained at 50,000 to 150,000 1 / h, for example about 60,000 to 100,000 1 / h, and the reductions in the reduction and oxidation catalyst are, for example, about 60,000 to 200,000 1 / h, preferably 70,000 to 150,000 1 / h. The present technology is particularly suitable for use in situations where the fuel is burned or has been burned in a combustion plant, which is an oil or gas boiler, a gas turbine, a diesel power plant or a similar energy plant.

N & 25o As stated above, in one application, the present technology can be applied to produce thermal energy from a hydrocarbonaceous fuel by combustion in at least two stages. In such a solution, in the first combustion stage, the first part of the fuel is burned in the combustion plant to produce heat and nitrogen and oxygen oxide-containing o 30 exhaust gas. The heat and exhaust gas from the first combustion stage are then recovered. The second part of the fuel is fed in the second combustion stage to the exhaust gas from the first combustion stage. Air is still supplied to form the combustible gas mixture. The gas mixture thus obtained is catalytically combusted to produce heat and decompose nitrogen and oxygen oxides. As described above, reducing conditions are maintained in at least one catalyst zone and the combustion is carried out under these conditions at a temperature above 600 ° C.

The heat from the second combustion stage is recovered.

In one application, the second combustion stage burns at least 10%, preferably 15-80 mol%, of the total amount of hydrocarbonaceous fuel.

With the help of the solution, a significant part can be produced in the second combustion stage, which adds about 60% of thermal energy to the primary energy source.

In one application, the flue gas of a thermal boiler, turbine or diesel power plant is used as a cooling and heat transfer medium in catalytic combustion.

In the stoichiometric catalytic combustion without a cooling inert excipient, the temperature rises above 2500 ° C according to the modeling.

This is because catalytic combustion is about twenty times faster than thermal.

In the applications shown in Fd, in which the temperature is raised to at least 600 ° C but preferably not more than 1000 ° C, catalytic combustion preferably uses thermal energy plant flue gases inert to maintain the temperature of the catalytic combustion of the heat storage and transfer medium in a preselected temperature range. .

It has been found that the non-combustible gases contained in the inlet gases, such as nitrogen and carbon dioxide, do not react under the conditions shown but equalize the heat as inert components and prevent an uncontrolled rise in temperature. 00 S In the above applications, the thermal energy contained in the combustion gases is recovered.

Recovery can be performed in at least one heat transfer step, where = heat energy is preferably transferred to water, air or other liquid or gaseous medium.

Ao a N In another embodiment, the present technology is applied to the catalytic purification of exhaust gases containing hydrocarbons and hydrocarbons, hydrocarbons, and soot particles from power plants using hydrocarbonaceous fuel 3 30 - under reducing and oxidizing conditions.

In this solution, fuel and air are fed to the exhaust gases to form a gas mixture and the gas mixture is subjected to a single or double reaction at a temperature of more than 600 PC.

secondary catalytic combustion to reduce nitrogen oxides and oxidize wedding, hydrocarbons and soot particles. In so doing, the NOx emission level of the gas from the catalytic combustion plant shall be 1 ppm or less and the CO and VOC emission levels shall not exceed 2 ppm. Small soot particles also burn at the preferred operating temperature of the exhaust burner at 850-1000 ° C, as the soot ignites at about 600 ° C and burns at an accelerating rate above it. An exhaust gas burner using the same fuel as a thermal boiler has several - advantages over selective (SCR) or non-selective (SNCR) NOx emission reduction plants: - Seo is a more efficient eliminator of NOx, CO and VOC emissions. It can achieve a level of about 1 ppm for NOx emissions and a level of 2 ppm for CO and VOC emissions, depending on the catalyst solution.

- It can be used to burn small soot particles.

- It can increase the boiler's thermal energy production by about 60%.

- It does not require a separate supplemental fuel or a separate storage and dosing system.

- The precious metal catalysts it contains have a longer service life than SCR catalysts, in which the thermal and chemical resistance of the catalyst (V, Os) used is lower than that of the precious metals. The new replacement SCR catalysts are various zeolites, which in turn are sensitive to sulfur poisoning.

© - SCR catalysts are 5-10 times larger in size than precious metal catalysts. There is no significant difference in their prices, as the size difference compensates for one of the 25 unit price differences. Precious metal catalysts cost about 60 - 70 € / dm3 and SCR catalysts cost about 10 € / dm ’.

z - EPA has demonstrated the SCR catalyst to have NOx removal costs of n.

a 1400-2000 USD / t NOx. The cost of a catalytic flue gas burner is substantially lower. The facility is smaller and simpler. The reducing agents used in SCR plants, ammonia (NFH3) or urea, are approximately the same as the fuels, but do not produce usable thermal energy.

- The biggest difference arises when the exhaust burner can produce additional energy at a competitive cost.

In this case, the elimination of NOx, CO and VOC emissions would take place as a by-product without separate cleaning costs. - Ammonia is transported and stored as a 27% aqueous solution because it is very toxic. - SCR reduction produces a ammonia leakage of 2-5 ppm (EPA) which must be catalytically oxidised.

In the following, the applications of the present technology will be considered on the basis of the accompanying drawings.

Figures 1 and 2 show two embodiments, where Figure 1 illustrates a solution in which both thermal and electrical energy are produced from fuel in a power plant (power plant), whereby the exhaust gas of the energy plant is primarily cleaned by a catalytic combustion process.

Figure 2, in turn, shows a solution in which heat is produced in a thermal power plant on the one hand and in a catalytic combustion process on the other.

As can be seen from the drawings, reference numerals 10; 20; 30 and 50 denote a thermal combustion boiler, diesel power plant, gas turbine or similar energy plant or power plant using gaseous or liquid fuel.

In the case of Figure 1, the fuel is fed mainly to an energy plant where thermal energy is produced, in addition to which part of the thermal energy thus produced produces electricity. = In both cases, gas N 25 from the exhaust outlet of the power plant is directed to the mixing chamber 12; 22, into which additional air is blown and fuel is injected.

The mixing chambers may comprise a distribution network. 7 One application uses a mixing cell structure.

An example of such is the solutions described, for example, in utility models 10627 or CN205001032. N Thus, the distribution network can consist of obliquely corrugated steel foils stacked or wedged on top of each other, the waves crossing.

The foils can be attached to each other at intersections &, for example, by resistance welding or soldering.

The flow channels formed by each layer of the cell intersect with each other, causing mixing and turbulence in the flow at higher flow rates.

In a direct channel cell, the flow is laminar. Then the dimensionless Sherwood (Sh) figure describing the mass transfer is about 3 with a flow velocity of 10 m / s. In a mixing cell with a metal body, it is about 10-12.

From the mixing chamber, the gas passes through a static mixer 13; 23 to catalyst 14; 24,

25. Behind the catalyst (in the flow direction of the gas mixture) is a non-shown linear lambda sensor arranged to measure and contribute to the control of the air / fuel ratio and a temperature sensor to control the temperature.

One or two catalysts 14; 24, 25, the gas passes, for example, to one or more heat exchangers 15 made of welded fin pipes; 27, in which heat is transferred to water or other utilization. Heat exchangers 15; 27, may be, for example, made of welded tubes, such as the previously ribbed tubes.

Figures 3 and 4 show the structure of the catalytic combustion system in more detail. In the figure, reference numerals 30 and 50 denote the production of primary energy, for example by a diesel engine, a gas turbine or a combustion boiler, from which the exhaust gas is supplied - fuel supply channels 31; 51 along. Air is supplied to form a gas mixture by fans 37; 57. The mixture is stirred prior to the catalyst zone by passing it through a static mixer 38; 58 through. Preferably, the mixture is rich prior to introduction into the catalyst zone. ©> 25 In the case of Figure 3, the catalyst zone comprises a cross-flow catalyst 33. In the case of Figure 4 =, the catalyst zone comprises a recuperative heat exchanger catalyst.

O = a from the first, typically reducing catalyst zone 33; The resulting gas mixture N 53 is passed to a second catalyst zone 35; 55, which typically comprises an oxidation catalyst 30 - converter. Additional air is then supplied to the gas mixture by a secondary air supply fan N 39; 59.

Prior to start-up, the catalyst or catalysts are typically preheated, e.g., with a hot air blower, gas burner, or similar heater, above the reaction temperature of the catalyst.

The first catalyst in the exhaust gas burner may be a conventional straight duct catalyst when the temperature difference between the exhaust gas and the ignition temperature of the fuel is small (<150 ° C) if the carbon monoxide (CO) and nitrogen dioxide (NO 2) concentrations in the exhaust gas are high. Carbon monoxide ignites in the catalyst already at about 150 ° C and the other oxygen of nitrogen dioxide is easily released and reacts aggressively.

A cross-flow or rotary cell recuperative heat exchanger catalyst 53 is required when the incoming gas temperature is substantially lower (> 150 ° C) than the Ignition Temperature of the fuel used in the catalyst.

In the device according to the invention, the change of the three-way catalyst is 50,000 to 150,000 1 / h, preferably 60,000 to 100,000 1 / h, depending on the fuel. In the reduction and oxidation catalysts, the exchange is 70,000-200,000 1 / h, preferably 60,000-150,000 1 / h. The thermal energy of the hot gas from the second catalyst zone is recovered - in a heat exchanger 36; 56, where it is transferred to water, for example. Heat exchangers 36; 56, may be, for example, made of welded tubes, such as those previously fined. After the heat exchanger, there may be a suction fan 40; 60, unless the powers of the primary power plant and co S auxiliary air fans are sufficient to carry sufficient gas through the equipment. About the hardware

N 2 25 - introducing exhaust gas, ie purified exhaust gas, into the exhaust pipe, eg 41; 61. p

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Example Generation of additional energy - Thermal natural gas boiler with a capacity of 60 MW - Exhaust gas supply 61,000 Nm '/ h - Supplementary air supply 35,000 Nm' / h - Additional natural gas supply 24 g / Nm ”96,000 Nm 'ssi - Additional energy from combustion 35.2 MW or 59% (calorific value 55 MJ / k) - Temperature after combustion 920 * C at inlet temperature 150 * C - Reduction of NOx - NOx emission 500 mg / Nm ”- Total NOx 61.000 Nm” / hx 500 mg / Nm = 30.5 kg / h - Comparison to SCR plant SCR plant reduction costs according to the lowest cost in the EPA calculation = 1400 USD / ton x 30.5 kg / hx 0.98 = 41.8 USD / h - Annual cost with SCR technology = 8000 h / ax 41.8 USD / h = 344,400 USD / a If the energy produced by the catalytic afterburner is not more expensive than the control energy co output, then the removal of NOx from the thermal boiler costs nothing, ie the annual savings would be N 344,400 USD.

At the same time, NOx emissions can be reduced to 1 ppm and CO and VOC-g 25 emissions can be reduced to less than 2 ppm by two-stage combustion (Figure 4). 3 E In order to achieve the objects, the invention is characterized by the features set forth in the independent claims. io o 30

Reference numbers: 10 Primary energy production 11 Generator 12 Distribution networks 13 Static mixer 14 3-way catalyst 15 Heat exchanger 20 Primary energy production. 22 Distribution networks 23 of static mixer 24 reduction catalyst 25 without dividing network 26 Oxidation catalyst 27 of heat exchanger 30 of primary return 31 of fuel supply channels 32 rich mixture 33 of cross-flow catalytic converter 34 Thin mixture of 35 Oxidation catalyst 36 of heat exchanger 37 of the fan 38 of static mixer 39 of the secondary air supply fan 40 a vacuum fan (if applicable) 41 Exhaust pipe (exhaust gas pipe ) 50 Primary energy yield. 51 Fuel supply ducts 52 Rich mixture 53 Recuperative heat exchanger catalyst 54 Lean mixture 55 Oxidation catalyst 00 56 Heat exchanger N 35 57 Fan 0 58 Static mixer? 59 Secondary air supply fan 2 60 Vacuum fan (if applicable) I 61 Exhaust pipe (exhaust pipe) = 40

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Claims (22)

Patent claims A process for the production of heat energy from a hydrocarbonaceous fuel, according to which process: - the fuel is burned in an incineration plant at an elevated temperature, - heat from the combustion is recovered and wherein - the combustion exhaust gases and soot particles are purified by catalytic exhaust combustion, fuel and air to form a gas mixture, the gas mixture is subjected to catalytic combustion at a temperature of at least 600 ° C, preferably above 600 ° C, to reduce the oxides of nitrogen and to oxidize carbon monoxide, hydrocarbons and soot particles, The catalytic combustion is carried out under reducing and correspondingly under oxidizing conditions in at least two stages. Method according to claim 1, characterized in that the exhaust gases, the fuel and the air are mixed with each other in interposed perforated feed pipes and in a static mixer (13, 23) to form an evenly mixed gas mixture. Process according to one of the preceding claims, characterized in that the gas mixture is subjected to catalytic combustion in a three-way catalyst (14) to an oxidation and reduction catalyst. Process according to one of the preceding claims, characterized in that the gas mixture is combusted in the three-way catalyst (14) using a stoichiometric oxygen / additive fuel ratio for the oxidation of CO and VOC compounds which are I have been unburned in the incineration plant and for the reduction of NOx emissions and the oxidation of soot particles. Process according to one of Claims 1 to 3, characterized in that the gas-N mixture is combusted in an oxidation and reduction catalyst (26, 24) first with a rich additive fuel / oxygen mixture for reducing the oxides of nitrogen. and with a lean supplemental fuel / oxygen mixture for oxidation of CO and VOC compounds as well as soot particles. Process according to any one of the preceding claims, characterized in that the temperature in the catalyst amounts to 850-1000 ° C at least under reducing conditions or under both reducing and oxidizing conditions. Process according to one of the preceding claims, characterized in that the volume velocity of the three-way catalyst (14) is from 50,000 to 150,000 1 / h, preferably 60,000 to 100,000 1 / h, and the volume rate of the reduction and oxidation catalyst (24, 26) amounts to 60,000-200,000 1 / h, preferably to 70,000—150,000 1 / h. Method according to one of the preceding claims, characterized in that the fuel is combusted in an incineration plant, which consists of an oil or gas boiler, gas turbine, diesel plant or a corresponding power plant. Process according to one of the preceding claims, characterized in that additional air and fuel are fed into the exhaust combustor and their feed is controlled by the temperature according to the catalyst and linear oxygen sensors according to the air / fuel ratio required by each catalyst. Process according to any one of the preceding claims for the production of heat energy from a hydrocarbonaceous fuel by combustion carried out in at least two stages, characterized by a combination in which, in the first combustion stage, a first part of the fuel is combusted. in a combustion plant A 25 for the production of heat and nitrogen- and oxygen-oxide-containing exhaust gas,? The heat and exhaust gas obtained from the first combustion stage are utilized separately, in the second combustion stage a second part of the fuel and air are fed into the exhaust gas obtained from the previous combustion stage to form a gas mixture. , the gas mixture thus obtained is catalytically combusted to produce heat and decompose the nitrogen and oxygen oxides, N whereby reducing conditions are maintained in at least one catalyst zone and the combustion is carried out under these conditions at a temperature of over 600 " C, after which the heat obtained from the second combustion stage is recovered. Process according to Claim 10, characterized in that the second combustion step burns at least 10%, most preferably 15-80 mol%, of the total amount of hydrocarbonaceous fuel. Process according to claim 10 or 11, characterized in that the second combustion stage is produced up to and including about 60% more heat energy to the primary energy source. Process according to one of the preceding claims, characterized in that the combustion gases of the thermal energy plant are used as inert heat storage and heat transfer means for pouring the temperature of the catalytic combustion within a preselected temperature range. - Process according to any one of the preceding claims, characterized in that the catalysts used in the combustion are coated with stable metal oxides, in particular with oxides, the cation of which consists of Al, Ce, Zr, L or Ba, and in which noble pallets, such as Pd, Pt, Rh, or the mixed oxides of these base metals are attached. - Process according to one of the preceding claims, characterized in that the noble metal catalysts are non-toxic and do not generate toxic compounds in reactions, as in traditional SCR catalysts. N A method according to any one of the preceding claims, characterized in that the heat energy contained in the gases generated during combustion is utilized? at least one heat transfer step, whereby heat energy is transferred to water, air or any other liquid or gaseous medium. T a N 17. Process for catalytic purification, under reducing and oxidizing conditions, of o 30 - exhaust gases containing nitrogen oxides and carbon monoxide, hydrocarbons and soot particles in power plants, using hydrocarbonaceous fuels, characterized by dewatering - fuel and air are fed into the exhaust gases and The gas mixture is subjected to a two-stage catalytic combustion carried out at a temperature above 600 ° C to reduce the oxides of nitrogen and to oxidize carbon monoxide, hydrocarbons and soot particles. Process according to Claim 18, characterized in that the emission level of the NOxs obtained from the catalytic combustion amounts to 1 ppm or less and the level of CO and VOC emissions amounts to a maximum of 2 ppm. Process according to any one of claims 17 or 18, characterized in that - the catalytic combustion is carried out in a catalyst in which the temperature is maintained at 850-1000 ° C. Process according to one of Claims 17 to 19, characterized in that the gas mixture is combusted in a three-way catalyst using a stoichiometric oxygen / additive fuel ratio for oxidizing CO and VOC compounds which have remained unburned in the combustion plant and for reducing NOx. emissions and oxidation of soot particles. Process according to one of Claims 17 to 20, characterized in that - the gas mixture is combusted in an oxidation and reduction catalyst (26, 24) first with a rich additive fuel / oxygen mixture for reducing the oxides of nitrogen and with a lean additive. egg fuel / oxygen mixture for oxidation of CO and VOC compounds and soot particles. o N Method according to claims 20 or 21, characterized in that The volume velocity of the N & 25 - three-way catalyst amounts to 50,000-150,000 1 / h, preferably to - 60,000—100,000 1 / h and the volume velocities of the reduction and oxidation catalyst amount to .000 I to 60,000-200,000 1 / h, preferably to 70,000—150,000 1 / h. a a N N N LO 00 O N