KR20200130261A - Method for producing heat in the plant - Google Patents

Abstract

A method of producing thermal energy from a fuel containing hydrocarbons. According to the invention, the fuel is burned at an increased temperature in a combustion plant, the heat obtained from the combustion is recovered and the exhaust gases and soot particles of the combustion are removed by catalytic exhaust-gas combustion. Fuel and air are supplied to the exhaust gas of the present invention to form a gas mixture, which performs catalytic combustion at a temperature of 600° C. or higher to reduce nitrogen oxides and oxidize carbon monoxide, hydrocarbons and soot particles. This solution can be used to significantly reduce the levels of NOx, CO and VOC emissions of gases. The thermal energy produced by the catalytic combustion process can also be used to produce heat, in which case the supply of fuel is divided between the combustion plant and the catalytic combustion process.

Description

Method for producing heat in the plant

The invention relates to the reduction of combustion gas emissions in energy plants. The invention also relates to the heat production of boilers, gas turbines, diesel plants and similar plants.

In particular, according to the preamble of claim 1, the present invention relates to a method for the catalytic removal of combustion gases, hydrocarbons and soot particles containing nitrogen oxides and carbon monoxide in an energy plant using a fuel having a hydrocarbon content.

The invention also relates to a method for producing thermal energy from a fuel having a hydrocarbon content according to the preamble to claim 19. According to such a method, the fuel is combusted at an increased temperature, the heat obtained from the combustion is recovered, and the exhaust gas and soot particles discharged from the combustion are purified using catalytic exhaust gas combustion.

Globally, emissions of nitrogen oxides (NOx), carbon-oxides (CO), carbon-dioxides (CO ₂ ) and hydrocarbons (VOC) generated through energy production are limited to prevent the greenhouse effect. In Europe, several directives aimed at this have been issued for heat boilers, process equipment, fireplaces, etc.

In this case, the emission limit for greenhouse gases was set either directly or as an aid to the efficiency or emission limit. In the United States, EPA and Kavar set limits on nitrogen oxides, hydrocarbons and their compounds. Corresponding development is taking place in China.

For example, in Beijing, a limit of 30 mg/m ³ is set for NOx and a limit of 80 mg/m ³ is set for a boiler.

The limit is so tight that it cannot be achieved with a conventional hot combustion device without post combustion. This strong austerity trend will also appear in other Chinese industrial areas.

Prior to the aforementioned emission limits, Beijing has already begun targeting even more stringent limits. For NOx the target is zero, and even for CO, the target is substantially lower than the previous limit.

Commercial manufacturers of UltraLow NOx and NoNOx burners use flue gas recyclers, water emulsifiers, and gas preheating instead of flue gas post-treatment to efficiently mix burners. Despite the burner's NoNOx name, no single hot smoker manufacturer has achieved zero NOx emissions. The lowest reported value is 6 ppm and the O ₂ content is 3%.

Another alternative is flue gas purification. In general, nitrogen oxides are removed using a selective catalyst and a non-catalytic reducing agent (selective catalytic reducing agent, hereinafter abbreviated as “SCR”, and a selective non-catalytic reducing agent “SNCR”). At temperatures up to about 350°, the catalytic SCR achieves a 90% cleaning level. In the report, EPA specifies an average NOx conversion of SCR at 85%. Using non-catalytic SNCR equipment reduces the cleaning effect by about 20%. Its use was aimed at diesel vehicles.

However, the SCR apparatus requires a separate reducing agent, urea or ammonia and its dosing equipment, leading to significant investment and operating costs.

Urea is decomposed in an explosive device to form ammonia (NH ₃ ) and carbon monoxide (CO). Ammonia and urea are transported and stored in a water solution.

The ammonia content is 27% and urea is 32%. Ammonia is a highly toxic gas. When SCR plant is used, NOx emission reaches about 7~30ppm.

In addition, the CO emission limit requires a separate oxidation catalyst.

The use of ammonia as a reducing agent is based on the ability to selectively re-inject NOx into the lean gas mixture.

The high cost of SCR technology is caused by ammonia (NH ₃ ), which is required as a reducing agent in addition to selective reduction or urea, and expensive storage, capacity, heat transfer, and reduction equipment.

In addition, EPA estimated the replacement cycle of the SCR catalyst to be three years. The most common active holding force in the SRC catalytic device, that is, the catalyst is vanadium pentoxide (V ₂ O ₅ ). It is easily the most toxic among precious metals.

The SCR catalyst device is large because of its low space velocity. That is, 10,000-20,000 1/h. The space velocity of the noble metal catalyst device is 5-10 times greater. That is, the size of the noble metal catalyst device is about 1/5 to 1/10 that of the SCR catalyst device.

Other weaknesses of the SCR catalytic system are the risk during handling and transportation due to the leakage of NH ₃ (2-5 ppm) and the toxicity of NH ₃ . In particular, in the United States, for example, there is a request to replace the toxic SCR catalyst (V ₂ O ₅ ) with non-toxic zeolite.

In addition, there is a limit to the catalytic combustion by the so-called catalytic poison, which should not contain combus-thione gas. The most important of these are organic silicon, heavy metal, and phosphoric acid compounds. They permanently deactivate the catalyst system. Sulfur compounds do not damage platinum-operated catalyst devices, but sulfuric acid generated as a result of the reaction can cause corrosion on the surface of heat exchangers with temperatures above 100°C.

Reference may be made to prior art publications US 4,118,171, US 2017/153024, US 2009/284013.

The present invention eliminates some of the problems associated with the prior art and creates an entirely new type of solution for the production of thermal energy from hydrocarbon-containing fuels, and accordingly, energy using nitrogen oxides and carbon monoxide, hydrocarbons and fuels containing hydrocarbons. It is for catalytic purification of exhaust gas containing plant soot particles.

In a first embodiment of the invention, the exhaust gas of the energy plant is directed to an exhaust gas burner that catalytically oxidizes and reduces the gas to reduce the NOx, CO, VOC and particle content of the exhaust gas and simultaneously generate thermal energy. In general, NOx compounds are first reduced, and then CO, VOC compounds, and particulate impurities of gas are oxidized, while simultaneously generating heat energy that can be recovered.

In the second embodiment of the invention, thermal energy is produced in at least two units, wherein the heat energy is first produced in an energy plant by burning a fuel having a hydrocarbon content. Heat is recovered in heat exchangers, for example. Fuel and air are supplied to the exhaust gas obtained from combustion to form a gas mixture, which leads to catalytic combustion and is carried out at high temperatures.

By performing combustion in the presence of a catalyst under reduction and corresponding oxidation conditions at a temperature of at least 600°C, nitrogen oxides contained in the flue gas are reduced and carbon monoxide, hydrocarbons and soot particles are oxidized. Heat from catalytic combustion is also recovered.

More specifically, the solution according to the invention in question is characterized as being primarily specified in the characterization section of the independent claim.

Significant advantages can be obtained using the present invention.

As already mentioned above, the use of hot combustion or conventional flue gas purification methods cannot produce clean heat energy as currently required in Beijing. However, the use of catalytic flue gas combustion can reduce NOx, VOC, CO and particulate flue gas emissions from already operating boilers, diesel and gas turbine plants to near zero. The goal can be achieved with the solution according to the invention. At the same time, it is also possible to burn small soot particles produced in oil and gas boilers and diesel plants.

With the help of the invention, a method of purifying NOx, CO, HC and particle emissions of a thermal energy plant using a single device more effectively than using any existing production technology is created, while simultaneously producing additional energy. With the solution according to the invention, all emissions classified above are eliminated in a single unit.

Therefore, using the current method, it is possible to reduce the re-delay content of NOx components to be less than 1ppm, and oxidation is possible so that the residual content of CO and VOC components is less than 2ppm. Even small soot particles can be burned in flue gas burners at temperatures above 600°C. The preferred temperature range for the burner is 850-1000°C. Soot particles also burn rapidly in this range.

Simultaneous energy production makes it possible to use flue gases, such as heat boilers, turbines or diesel plants, as cooling and heat transfer materials during catalytic combustion. The inert thermal mass of the exhaust gas and flue gas is used in combustion for temperature control and heat transfer. With the help of the flue gas, the temperature can be kept within the degassing limit, preferably in the range of 850-1000°C.

Unlike other purification methods, the use of current methods can increase the thermal energy production capacity of heat boilers by up to 60%.

A flue gas burner can be added to any energy production unit, which emits less sulfur and particles, and is free from so-called catalytic unit poisons. On the other hand, NOx, CO and VOC emissions from energy sources are practically insignificant. After combustion, the small soot particles produced by oil boilers and diesel plants are also burned. Unless there is a stored POC catalyst or filter associated with the catalytic unit, it is desirable to arrange an intermediate chamber prior to heat recovery where the particles have time to burn before energy recovery.

The particles of diesel engines are mainly small, so-called nanoparticles. More than 90% of these have a diameter of less than 50 nm. They enter the lungs with the breathing air and partially pass through them into short blood circulation, causing many deaths. Nanoparticles contain carbon, water, hydrocarbons, and often sulfur and small amounts of other compounds. They are very porous. When hydrocarbons and sulfur compounds are oxidized and water evaporates, carbon is ignited on all surfaces and burns faster, but gaseous compounds burn more slowly. The temperature of the exhaust gas in the aforementioned range (850-1000° C.) is advantageous for this reaction, particularly for the combustion of carbon.

The use of exhaust gas burners can bring the emissions of heavily polluted existing energy production units to new and more stringent demand levels.

Exhaust gas burners can in principle be combined with boilers or heat exchangers to purify all types of gases, including NOx, CO and VOC emissions, since catalytic combustion operates below the LEL limit. If so, there is no safety risk of the same kind as a hot-fired boiler where the combustion of VOCs leads to a fatal accident.

In particular, since the amount of outgassing is of little importance to the operation and purification results of the exhaust gas burner, freedom can be given to the adjustment of the primary energy source and the selection of equipment. The boiler does not require the previous passive Low NOx or UltraLow. The NOx burner and air-fuel ratio can be optimized for maximum power. For diesel engines, exhaust gas recirculation (EGR) or extremely lean to reduce NOx emissions. No mixing cost is required.

Exhaust gas burners are also suitable for energy plant operations that do not always meet emission requirements according to strict norms. Since factories have long lifespans and require large investments, investments in reducing emissions are often worth making. The new plant forms another application.

Hereinafter, the present invention will be reviewed in detail with the help of description with reference to the accompanying drawings.

Figure 1 shows a process diagram of one embodiment.
Figure 2 shows the process diagram of the second embodiment.
Figure 3 shows the process diagram of the third embodiment.
Figure 4 shows the process diagram of the fourth embodiment.

Specific example

"Energy plant" in this context refers to a combustion plant that produces thermal energy, such as thermal energy, which produces energy from fuels with a hydrocarbon content mainly with the aid of a boiler, diesel turbine or gas turbine.

In the first embodiment, the term "fuel having a carbon content" also refers to a fuel comprising compounds that consist primarily of carbon and hydrogen, such as hydrocarbons, but not. In addition to hydrocarbons, fuels may contain compounds with an oxygen content such as ethers, esters and alcohols. Examples of fuels having a carbon content according to the first embodiment include petroleum, gasoline, diesel and natural gas.

In the second embodiment, the term "fuel with carbon content" refers to a combination that mainly comprises an alcohol (hydroxy) group, an ether group or an ester group, or together with such groups constitutes a carbon compound such as a lower hydrocarbon compound. . These fuels are a variety of biofuels produced from biomass such as lignocellulose, vegetable oils and animal fats.

The expressions CO and "VOC emissions" and the corresponding expressions "NOx emissions" and "small particle emissions" mean that the amounts (as mass) of CO, VOC, and NOx gases and corresponding soot particles are contained in the exhaust gas. .

A “concentrated” fuel/oxygen (or fuel/air) mixture contains a greater amount of fuel (relative to oxygen), and again a smaller amount of fuel.

In the present invention, solutions are made that generally treat exhaust gases and use catalytic exhaust gas burners to produce energy. This method can be applied to both heat generation and purification exhaust gases, as described in more detail below.

In this method, additional air and fuel are supplied to the exhaust gases from thermal bonding to form the amount of gas mixture required for catalytic combustion, after which the gas mixture is directed to the catalytic combustion zone for combustion. The heat obtained from the combustion is recovered. Combustion significantly reduces CO, VOC, NOx and soot particle emissions in catalytic combustion exhaust gases.

In one embodiment, exhaust gas, fuel, and air are evenly mixed to create a homogeneous gas mixture.

In this embodiment, additional air and fuel can be supplied to the exhaust gas burner, which supply can be controlled by a linear oxygen sensor for the temperature after the catalytic unit and the air/fuel mixture ratio required by each catalytic unit. .

For the reaction described below to take place, a large amount of fuel is most suitably added to the exhaust gas to achieve a rich or metering ratio. In the former case, only the reduction of NOx with nitrogen (N ₂ ) and oxygen (O ₂ ) occurs, and in the latter case, CO and VOCs are oxidized with carbon dioxide (CO ₂ ) and water (H ₂ O).

When working with concentrated mixtures, the second catalyst is best used when laying out the excess air feed required by the lean mixture. The best results are obtained following separate oxidation and reduction steps.

If you want to produce as much clean energy as possible, you have to spray the flue gas with air along with the fuel. The temperature should be appropriately limited to about 1000° so that nitrogen oxides do not occur during combustion. Unlike other purification methods, this method can increase the thermal energy production capacity of a heat boiler by up to 60% as described below.

In one embodiment, fuel and air are mixed in an enclosed perforated supply pipe and a static mixer to form an evenly mixed gas mixture.

Static mixers can be used to ensure the homogeneity of the particularly preferred gas mixture to ensure even combustion.

In one embodiment the catalytic combustion is reduced in one or more stages and subjected to corresponding oxidation conditions.

In one embodiment, catalytic combustion is carried out in at least two steps, particularly to reduce nitrogen oxides and to oxidize carbon monoxide, hydrocarbons and soot particles.

In one embodiment, the oxida-thione and reduction are converted to catalytic combustion in a three-way catalytic unit. The gas mixture can then be burned in a three-way catalytic unit using the combustion plant's metered oxygen/additional fuel ratio to oxidize unburned CO and VOC compounds in the combustion plant, reduce NOx emissions, and oxidize soot particles. .

If combustion occurs at temperatures above 600℃, soot particles also burn.

Or, in the reduction part of the second part of the catalytic device, to re-decompose NOx emissions with nitrogen (N ₂ ) and oxygen (O ₂ ) and oxidize most of the CO and VOC emissions with carbon dioxide (CO ₂ ) and water (H ₂ O). Use a rich mixture.

After that, air is added to the gas mixture to make it lean, and the mixture passes through an oxidation catalyst. The remaining CO and VOC emissions are oxidized. The heat energy generated in the next heat exchange step is used. It uses heat energy from water, for example with the help of a welded fin pipe radiator. The exhaust gas then leaves the boiler to the chimney and, if necessary, assisted by a suction fan.

In one embodiment, the gaseous mixture is combusted with an oxidation and reduction catalyst, initially using an enriched additional fuel/oxygen mixture to reduce nitrogen oxides and then adding a lean additional fuel/oxygen mixture to oxidize CO and VOC compounds and soot particles. use.

In reducing the noble metal catalyst, the reaction chain mainly takes place through steam-reforming and water-gas transfer reactions.

H ₂ O + HC -> H ₂ + CO and H ₂ O + CO -> H ₂ + CO ₂

And

H ₂ + NO _x -> N ₂ + H ₂ O.

Some of those reactions are direct oxidation and reduction reactions.

Catalytic combustion always occurs below the lower explosion limit (LEL). The fuel can often be the same as in the primary energy production unit.

If the combustion flue gas temperature after the pre-catalyst falls below 250°C and the fuel is natural gas or other fuel ignited at high temperature, the structure of the catalytic device is a cross-metal flow or recovery type ignited in a low place to maintain combustion It should be a regenerative heat exchanger. In the case of methanol or ethanol, the fuel mixture should be supplied as a support fuel.

The catalyst device used for combustion is stable metal oxide, Al, Ce, Zr, L, or Ba, and it is most suitable that noble metals such as Pd, Pt, Rh are attached.

These noble metal catalysts are not toxic, and toxic compounds are not generated in the reaction as occurs in conventional SCR catalyst devices.

The temperature of the catalytic device is at least 600°C, and in particular, it is 850-1000°C in both reducing and oxidizing conditions.

In the case of a three-way catalyst unit, the space velocity is maintained at a value of 50,000-150 000 1/h (e.g., about 60,000-100,000 1/h), whereas in the case of a reduction and oxidation catalyst unit, the space velocity is approximately 60,000-200,000 1 /h, for example, 70,000-150,000 1/h is preferable.

The present invention is particularly applicable to situations in which fuel is burned or burned in a combustion plant (oil or gas boiler, gas turbine, diesel plant or similar energy plant).

In one embodiment, a method of purifying exhaust gas or flue gas and generating clean energy occurs catalytically only in one or two steps. In such a method, the flue gas also has a thermal bonding and transfer role. Since catalytic combustion is considerably faster than heat, it is desirable to use flue or exhaust gases that are essentially inert for binding energy. This will avoid excessive temperature rise.

As mentioned above, by applying the present invention, it is possible to produce thermal energy from a hydrocarbon-containing fuel by carrying out combustion in at least two stages. In this way, some of the fuel is burned in the first combustion stage of the combustion plant to produce heat and exhaust gases with nitrogen and oxygen oxide content. After that, the heat and exhaust gas obtained in the first combustion step are recovered. In the second combustion stage, the second part of the fuel is supplied with the previous gas obtained in the first combustion stage. Air is also supplied to form a combustible gas mixture. The gas mixture thus obtained produces heat and is burned to decompose nitrogen and oxygen oxides. As described above, the reduced state is maintained in at least one catalytic device zone and combustion is carried out under these conditions at a temperature of 600°C or higher.

The heat from the secondary combustion stage is recovered.

In one embodiment, 15-80 mol% of the total fuel volume with hydrocarbon content is burned in 10% of the secondary combustion stage. With the aid of the method, a significant portion of the thermal energy added to the primary energy source, about 60%, can be produced in the secondary combustion stage.

In one embodiment the flue gas from a boiler, turbine or diesel plant is used as a cooling and heat transfer material in a catalytic device. In the absence of cooling inert additives in interfacial catalytic combustion, modeling shows that the temperature will rise above 2500°. This is because catalytic combustion is about 20 times faster than heat. In catalytic combustion where the temperature rises to at least 600°C in the above-mentioned embodiment, but preferably 1000°C, the flue gas of the thermal plant is best used as an inert heat storage and transfer agent to maintain the catalytic combustion temperature within a preselected temperature range. It is used suitably.

It has been shown that unburned gas contained in flue gas such as nitrogen and carbon dioxide does not react under the described conditions and acts as an inert component to heat to prevent uncontrolled temperature rise.

In the embodiment described above, heat energy contained in the gas obtained by combustion is recovered. Recovery can occur in at least one heat transfer step if the heat energy is most appropriately transferred to water, air or other liquid or gaseous medium.

In a second embodiment, the present invention provides for catalytic purification of exhaust gases, hydrocarbons, and soot particles containing nitrogen oxides and carbon monoxide, in an energy plant using fuels containing hydrocarbons, in reducing and oxidizing states. Applies to things. In this solution, fuel and air are supplied to the exhaust gas to form a gas mixture, and the gas mixture is subjected to a one- or two-stage catalytic combustion conducted at a temperature of 600° C. or higher to reduce nitrogen oxides and reduce carbon monoxide, hydrocarbons, and soot. Oxidizes particles.

In a second embodiment the present invention is applied to an energy plant using a fuel containing a hydrocarbon. Exhaust gas containing nitrogen oxides, carbon monoxide, hydrocarbons and soot particles is applied under the conditions of purification, reduction and oxidation with a catalyst.

In this method, fuel and air are supplied to the exhaust gas to form a gas mixture, and the gas mixture is brought to one-stage or two-stage catalytic combustion and carried out at a temperature of 600℃ or higher to reduce nitrogen oxides and oxidize carbon monoxide, hydrocarbons and soot particles. .

In this way, the NOx emission of gases obtained by catalytic combustion is less than 1 ppm, and the emission of CO and VOC is up to 2 ppm. In addition, small soot particles are burned at the operating temperature of the exhaust gas burner 850-1000°C, because soot is ignited at about 600°C and burns when the speed increases.

According to one embodiment, the current method is implemented as a continuously operated process.

In a continuous operation process, hydrocarbons are used both as a reducing agent and as an energy source. The production of additional energy is another attribute of the process.

In one embodiment, the oxidation of the particles and the production of clean energy are carried out at high temperatures (at least 1,000° C.). For both, it improves conversion efficiency as a particle oxidizer and energy producer. By higher temperature

Exhaust gas burners that use the same fuel as thermal boilers have several advantages over selective (SCR) or non-selective (SNCR) NOx emission reduction mechanisms:

- The efficiency of NOx, CO and VOC emissions is higher. It can be used to achieve about 1 level of NOx emissions, 2 ppm level of CO and VOC emissions according to the catalytic method.

- It can be used to burn small soot particles.

- It can be used to increase the heat energy production of the boiler by about 60%.

- No additional fuel or separate storage and dosing systems are required.

-The noble-metal catalyst device in it has a longer life than the SCR footing device, and the heat and chemical durability of the used catalyst (V ₂ O ₅ ) is inferior to that of the noble metal. The new alternative SCR catalysts are a variety of zeolites, susceptible to sulfur poisoning.

-The size of the SCR catalyst device is 5-10 times larger than that of the noble-metal catalyst device. The difference in price is not large because the difference in size compensates for the difference in unit price. Precious-metal catalysts are about 60-70 € ³ and SCR catalysts are about 10 € ³

-EPA proved that the NOx removal cost of SCR catalyst system is about 1400-2000 USD/t NOx. The cost of catalytic flue gas burners is quite low. The method is smaller and simpler. The reducing agent used in the SCR plant, ammonia (NH ₃ ) or urea, is about the same price as fuel, but does not produce usable thermal energy.

- The main difference is that the exhaust gas burner can be used to produce additional energy at a competitive cost. After that, NOx, CO, and VOC emissions are removed as by-products without separate purification costs.

- Ammonia is highly toxic and is transported and stored in 27% aqueous solution.

- A 2-5 ppm ammonia leakage (EPA) occurs in SCR reduction, which must be oxidized with a catalyst.

In the following, specific examples of the present invention will be reviewed based on the accompanying drawings.

Figures 1 and 2 show two specific examples. Figure 1 shows a solution in which both heat and electrical energy are produced from the fuel of the energy plant, which mainly uses a catalytic combustion process to purify the exhaust gases of the energy plant. Occurs when Figure 2 shows the catalytic combustion process while heat is generated in a thermal energy plant.

As can be seen in the drawings, reference numerals (10)-, (20), (30) and (50) denote boilers, diesel plants, gas turbines or other energy plants or plants using gas or liquid fuel. In the case of Figure 1, fuel is mainly supplied to an energy plant in which thermal energy is produced, and is produced by supplying additional electricity to it. At least part of the heat energy

In the case of the two figures, the exhaust gas of the energy plant is a mixing chamber 12 in the exhaust duct; It is led to (22), in which additional air is introduced and fuel is injected. The mixing chamber can constitute a network.

In one embodiment, a mixed honeycomb structure is used. For example, solutions disclosed in utility model 10627 or CN205001032. Thus, the distribution network can consist of diagonal steel folio sheets. Things that are stacked or folded on top of each other intersect at an angle. For example, resistance welding or brazing can be used to connect the foliosheets to each other at intersections. The flow paths formed in each layer of the honeycomb cross each other, causing mixing and turbulence of flow rates at high flow rates.

In a straight honeycomb, the flow is layered. The dimensionless Sherwood (Sh) number representing mass transfer is about 3 and the flow rate is 10 m/s. In mixed metal honeycombs it is about 10-12.

In the mixing chamber, the gas is passed through a static mixer (13); Catalyst device 14 via 23; Move to (24) and (25). Behind the catalytic unit (direction of flow of the gas mixture) is a linear lambda sensor (not shown), which is arranged to measure and adjust the air/fuel ratio and controls the temperature.

One or two catalyst devices 14; (24); (25) After the gas is welded to the connection of the frame pipe or several heat exchangers (15); (27), when heat is transferred to water or other useful purposes. For example (15); (27) The heat exchanger may be of a welded pipe, such as made of a ribbed pipe.

Figures 3 and 4 show the structure of the catalytic combustion system in more detail.

In the drawings, primary energy production using, for example, diesel engines, gas turbines or combustion boilers is indicated by reference numerals 30 and 50. The fuel includes supply ducts 31; It is supplied to the exhaust gas obtained through 51. To form a gas mixture, the air is supplied with a fan 37; Supplied by 57. The mixture is a static mixer 38; It is mixed before the catalyst zone by guiding through 58. It is preferred that this mixture is contained in an abundance before being directed to the catalyst zone.

In the case of Figure 3, the catalyst zone consists of a cross-flow catalytic device 33.

In the case of Fig. 4, the catalyst zone is composed of a recovery heat-emission agent-catalyst.

A first catalyst zone 33 which is generally reduced; The gas mixture obtained in (55) comprises a second catalyst zone (35); It leads to (55). In general, it constitutes an oxidation catalyst device. Then auxiliary air supply fan 39; Supply additional air to the gas mixture by means of (59). Before starting, the catalytic device is usually preheated. For example, a warmer, gas burner, or other heater is used to set the reaction temperature above the catalyst device.

The first catalytic device of an exhaust gas burner can be a straight-pipe catalytic device if the temperature difference between the ignition temperature of the exhaust gas and the fuel is small (<150°C).

When the content of carbon monoxide (CO) and nitrogen oxides (NO ₂ ) in the exhaust gas is high, carbon monoxide is already ignited in the catalytic device at about 150°, and the second oxygen of nitrogen oxide is easily separated and reacts aggressively.

When the temperature of the inlet gas is significantly lower than the ignition temperature (> 150°C) of the fuel used for the catalyst, a cross-flow or rotating honeycomb structure once-through heat-exchange catalyst device 53 is required.

In the device according to the invention, the space velocity of the three-way catalyst device is 50,000-150,000 1/h, preferably 60,000-100,000 1/h, depending on the fuel. The space velocity of the catalyst for reduction and oxidation is 70,000-200,000 1/h, preferably 60,000-150,000 1/h.

The heat energy of the hot gas obtained in the second catalytic zone is transferred to, for example, a heat exchanger 36; Recovered from (56). Heat exchanger 36; 56 can be made of, for example, a welded pipe, preferably a ribbed pipe.

After heat transfer, (40); There may be 60 suction fans. If the output of the reserve energy plant and the additional air fan is sufficient to deliver sufficient gas through the device, the exhaust gas (e.g., purified exhaust gas) is led from the appliance to the exhaust pipe (e.g. (41); (61)). .

In one embodiment, the current apparatus for burning a flowing fuel with a hydrocarbon content with oxygen or air is configured as follows. According to the flow sequence of the material being processed

- Includes mixing zone, catalytic combustion zone, heat recovery zone, gas removal zone, etc.

- In the mixing zone, a transfer connection for gas to be purified, a transfer connection for fuel, and a static mixer capable of evenly mixing gas and fuel are installed.

- The catalytic combustion zone contains at least two cohesive combustion zones in the flow direction, of which reducing conditions are created in the first and second oxidation conditions.

- The heat recovery zone contains a heat transfer element and is connected to the catalyst zone to recover the released heat.

Example

Energy production Additional energy production

- Thermal boiler using natural gas, output 60MW

-Exhaust gas input 61.000Nm ³ /h

-Additional air input 35.000Nm ³ /h

-96.000Nm ³ to 24g/Nm ³ additional natural gas input

- Additional energy generated from combustion 35.2 MW, ie 59% (heat value 55 MJ/k)

- After combustion temperature is 920℃, input temperature is 150℃

- NOx reduction

-NOx emission 500mg/Nm ³

-NOx 61.000Nm ³ /hx 500mg/Nm ³ Total amount = 30.5kg/h

Comparison of SCR plant

EPA = 1400 USD/ton x 30.5 kg/h x 0,98 = 41.8 USD/h savings in SCR plant according to the lowest cost calculated

Annual cost with SCR technology = 8000 h/a x 41.8 USD/h = 344.400 USD/a

If the energy produced after catalytic combustion is not more expensive than comparable energy production, there is no cost to removing NOx from a thermal boiler. That is, the annual savings are $344.400. At the same time, NOx emissions can be raised to the level of 1 ppm and CO and VOC emissions can be reduced to less than 2 ppm using two-stage combustion (Figure 4).

In order to achieve the above goal, the present invention has the characteristic aspects set forth in the independent claims.

Industrial availability

The current solution is CO emissions and NOx such as boilers, diesel plants, gas turbines, etc. It is suitable as a simultaneous power cleaner of VOC. The solution according to the invention is also suitable for burning particles, for example in solid fuel boilers and diesel plants, without additional equipment or additional costs. It is also suitable for generating additional energy from boilers, diesel plants and gas turbines.

If the method according to the invention is used, the residual amount can be reduced to less than 1 ppm by reducing nitrogen oxides (NOx), and the residual amount can be made less than 2 ppm by oxidizing carbon monoxide (CO) and hydrocarbons (VOC). These values can be achieved even with high primary energy source emissions. Exhaust gas burners can also burn small soot particles, making it possible to replace particle filters in boilers and diesel engines. Thanks to the solution according to the invention, primary energy plants do not need low or ultra-low NOX burners, and diesel engines do not require EGR or very low mixing ratios to reduce NOX emissions.

This will maximize the output of the primary energy plant. In addition to this, the use of the method according to the invention makes it possible to additionally produce about 60% of thermal energy for the primary energy source. This is particularly the case when the exhaust gas produced in the primary combustion is used as a cooling and heat exchanger in the catalytic combustion, and fuel is supplied to the exhaust gas to form a two-stage catalytic combustion.

10 Primary energy production
11 generator
12 distribution network
13 static mixer
14 3-way catalyst device
15 heat exchanger
20 Primary energy production
22 distribution network
23 static mixer
24 Reduction catalyst device
25 air distribution network
26 Oxidation catalyst device
27 heat exchanger
30 Primary energy production
31 fuel supply pipe
32 thick mixture
33 Cross flow catalyst device
34 Lean Mixture
35 Oxidation catalyst device
36 heat exchanger
37 fans
38 static mixer
39 Secondary-air supply fan
40 vacuum fan (if required)
41 exhaust pipe (exhaust-gas pipe)
50 Primary energy production
51 fuel supply pipe
52 thick mixture
53 once-through heat exchanger-catalyst
54 Lean Mixture
55 Oxidation catalyst device
56 heat exchanger
57 fans
58 static mixer
59 Secondary-air supply fan
60 vacuum fan (if required)
61 exhaust pipe (exhaust-gas pipe)

Claims (25)

A method for catalytic removal of combustion gases, hydrocarbon substances, and soot particles containing nitrogen oxides and carbon monoxide in a plant using a fuel containing hydrocarbons, under conditions of reduction and oxidation,
-Supplying fuel and air as exhaust gases to form a gas mixture,
-A method characterized in that the gas mixture undergoes one or more catalytic combustion, which is carried out at a temperature above 600° C., to reduce nitrogen oxides and oxidize carbon monoxide, hydrocarbons and soot particles. The method of claim 1,
The method, wherein the emission level of NOx of the gas obtained from the catalytic combustion is 1 ppm or less and the level of CO and VOC emission is 2 ppm or less. The method according to claim 1 or 2,
The catalytic combustion is carried out in a catalytic device, wherein the temperature is maintained at 850-1000°C. The method according to any one of claims 1 to 3,
The mixed gas is combusted in a three-way catalyser using stoichiometric oxygen/extra-fuel to oxidize VOC compounds and CO remaining unburned in the combustion plant and reduce NOx emissions. Oxidizing soot particles, method. The method according to any one of claims 1 to 4,
The mixed gas is combusted in an oxidation and reduction catalytic apparatus, first reducing nitrogen oxides with an enriched addition-fuel/oxygen mixture, and then oxidizing CO and VOC compounds and soot particles with a deficient additional-fuel/oxygen mixture. , Way. The method according to claim 4 or 5,
The space velocity of the three-way catalyst device is 50,000-150,000 1/h, preferably 60,000-100,000 1/h, and the space velocity of the reduction and oxidation catalyst expander is 60,000-200,000 1/h, preferably 70,000-150,000 1/h. h, how. The method according to any one of claims 1 to 6,
The process, wherein the catalytic combustion is carried out in at least two steps under reducing and corresponding oxidizing conditions. -The fuel is burned at increasing temperatures in the combustion plant,
-The heat available from combustion is recovered,
-A method of generating thermal energy from combustion containing hydrocarbons according to the method in which the exhaust gases and soot particles of the combustion are removed by catalytic exhaust-gas combustion,
-Fuel and air are supplied to the exhaust gas to form a gas mixture,
The method, characterized in that the gas mixture is subjected to catalytic combustion at a temperature of at least 600° C., preferably above 600° C. to reduce nitrogen oxides and oxidize carbon monoxide, hydrocarbons and soot particles. The method of claim 8,
The process, wherein the catalytic combustion is carried out via one or more steps, preferably at least two steps, in reducing and corresponding oxidizing conditions. The method according to claim 8 or 9,
The method, wherein the exhaust gas, fuel and air are uniformly mixed together in a nesting, perforated supply pipe and static stirrer to produce a gas mixture. The method according to any one of claims 8 to 10,
Wherein the gas mixture is catalytically combusted in a three-way oxidation and reduction catalytic device. The method according to any one of claims 8 to 11,
The mixed gas is combusted in a three-way catalyser using stoichiometric oxygen/extra-fuel to oxidize VOC compounds and CO remaining unburned in the combustion plant and reduce NOx emissions. Oxidizing soot particles, method. The method according to any one of claims 8 to 11,
The mixed gas is combusted in an oxidation and reduction catalytic apparatus, first reducing nitrogen oxides with an enriched addition-fuel/oxygen mixture, and then oxidizing CO and VOC compounds and soot particles with a deficient additional-fuel/oxygen mixture. , Way. The method according to any one of claims 8 to 13,
The temperature of the catalyst device is at least 850 to 1000° C. in a reducing condition or a condition of both reduction or oxidation. The method according to any one of claims 8 to 14,
The space velocity of the three-way catalyst device is 50,000-150,000 1/h, preferably 60,000-100,000 1/h, and the space velocity of the reduction and oxidation catalyst expander is 60,000-200,000 1/h, preferably 70,000-150,000 1/h. h, how. The method according to any one of claims 8 to 15,
The method, wherein the fuel is burned in a combustion plant, the combustion plant being an oil or gas boiler, a gas turbine, a diesel power plant or similar energy plant. The method according to any one of claims 8 to 16,
The method, wherein additional air and fuel are supplied to the exhaust-gas burner and their supply is controlled by the temperature after the catalytic device and the linear oxygen sensor, depending on the air/fuel ratio required by each catalytic device. A method according to any one of claims 8 to 17 for generating thermal energy from a fuel having hydrocarbons using combustion carried out in at least two stages, comprising:
-In the part of the first combustion stage of the fuel, it is combusted in the combustion plant to produce heat and exhaust gas with nitrogen- and oxygen-oxides,
-The heat and exhaust gas obtained in the first combustion step are recovered separately,
-In a second combustion step, the exhaust gas obtained from the previous combustion step is supplied together with the fuel and a second portion of air to form a gas mixture,
-The resulting gas mixture is characterized by combustion by combustion by a catalyst to generate heat and to remove nitrogen and oxygen oxides,
The method, wherein reducing conditions are maintained in at least one catalytic zone, and combustion is carried out at a temperature above 600° C. in these conditions, after which the heat obtained from the second combustion step is recovered. The method of claim 18,
In the second combustion step, at least 10 mol%, most suitably 15-80 mol%, of the total amount of fuel with hydrocarbons is burned. The method of claim 18 or 19,
The method, in which as much as about 60% of additional thermal energy is generated for the primary energy source. The method according to any one of claims 8 to 20,
The method, wherein the flue gas of the thermal energy plant is used as an inert heat storage and transfer agent to keep the temperature of the catalytic combustion within a preselected thermal range. The method according to any one of claims 8 to 21,
The catalyst device used for combustion is surface-treated with a stable metal oxide, preferably an oxide of a cations of Al, Ce, Zr, L, or Ba, and mixed with noble metals such as Pd, Pt, Rh, or nonmetals thereof. Oxide is attached, the method. The method according to any one of claims 8 to 22,
The method, wherein the noble metal catalyst is non-toxic and does not produce toxic substances in reactions in traditional SCR catalysts. The method according to any one of claims 8 to 23,
The method of claim 1, wherein the thermal energy contained in the gases resulting from combustion is recovered in one or more heat exchange steps, wherein the thermal energy is transferred to water, air, or some other liquid or gaseous medium. Use of the method according to any one of claims 1 to 7 for producing recoverable thermal energy.

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