Method of treatment of waste gases containing harmful substances to the regenerative heat exchanger, and a device for its implementation

 

(57) Abstract:

The invention relates to a method of cleaning gases and devices for these methods. Gaseous waste serves for heat exchange with a different environment, with a fixed or circulating accumulating masses, consisting partly of the catalytic material. From the hot surface of the storage mass is reducing agent so that it does not touch other surfaces and exhaust gases. The reducing agent serves in such depth, until it reaches the surface of the heating of the catalyst, not getting on the heating surface of taprobanica beneath accumulating masses. For these purposes, the device is equipped with caps, one of which is a tube with at least one outlet, equipped with a nozzle. The result of the invention in the environment are not waste, saturated with ammonia. 2 S. and 4 C.p. f-crystals, 4 Il.

The invention relates to a method for treatment of waste gases containing harmful substances to the regenerative heat exchanger and in a state of heat exchange with a different environment, with a fixed or circulating accumulating mass, consisting at least partially of catalytic to materiality as for the heater, and atopologically.

In power plants and in the combustion chamber of a gaseous wastes are used in the regenerative heat exchanger for heating air flowing to the combustion. This significantly reduces the content of oxides of nitrogen (NOx) in the exhaust gas, and in this case, the accumulating mass - stationary or circulating regenerative air heater are fully or partially active catalytic material, and, for example, as a reducing agent is added, primarily ammonia (NH3). When it comes to reducing the content of nitrogen oxides by catalytic in which you are restoring /deoxidizing/ oxides of nitrogen with the addition of NH3in the presence of catalyst present in the regenerative air heater or the regenerative heat exchanger. Usually containing oxides of nitrogen gaseous wastes are flue gas fire heating, circulating at the end of the steam boiler for heating air flowing to the combustion, in the regenerative heat exchanger.

For these purposes known to the introduction of NH3in the form of vapors mixed with air as a carrier gas under pressure or the solution is I of oxides of nitrogen in gaseous waste in installations for fire heating. Using mixing zones, using the appropriate insert inside the ongoing channels for gaseous waste, trying to get in the flow of waste gases entering the catalyst, the distribution of ammonia and heating without dividing it into separate threads. The catalyst or accumulating mass, considering the optimal reaction temperatures in the process gas is pre-connected to the regenerative heat exchanger to transfer the heat of waste gases in the air going to the combustion and supplied for fire heating. As the catalyst proved itself primarily stationary catalysts with directed vertically downward flow of waste gases, many of which affect purified from nitrogen exhaust gases alternately. Fixed catalysts with a honeycomb structure, contain as catalytic active compounds vanadium compounds that favor the exchange reaction of nitrogen oxides and NH3previously introduced into the flow of gaseous wastes and mixed on the way to the catalyst when the exact distribution. Reaction with nitrogen oxides present in the gaseous waste, leads essentially to obtain molecular nitrogen and water as PR is tov 0195075 and 0257024 known additive reductant with untreated, flue or exhaust gas, or with purified gas or air, or gas and air. NH3is added either in the flue gas before it enters the catalyst, or to the heated supply air before it enters the catalyst, or combination of both. In any case present in the flue gas components, namely NOxare converted by catalytic into harmless components.

In known heat exchangers leak appears as if making NH3with air and flue gas. Despite the seal, making the NH3with air it is impossible to prevent a certain amount of reducing agent from the purified gas in the purified flue gas. This proportion, thus, vanishes and loads the additional section of the installation. Finally, when applying by air, i.e., with cold air heat exchanger also affected catalytically inactive, located in areas of low temperature heating surfaces. In the areas of heating surfaces, partly due to compensation and/or absorption, for example, by heating the air going to the combustion, NH3may be transferred from the air in the flue gas. At the same time as neeeeee saturation with ammonia flying dust, present in the flue gas.

The basis of the invention is the task of creating a method and device of the aforementioned type, with which you can avoid these shortcomings to achieve, firstly, a high degree of response in the sense of maximum reduction of NOxand , secondly, to further prevent reductant into the flow of flue gas and, thus, into the environment.

According to the claimed method, this task is solved in such a way that the reducing agent is fed directly to the catalyst separately from the gaseous waste containing harmful substances, without any contact with other surfaces. The basis of the invention lies in the experience gained direct injection of reducing agent in the shortest way with the hot surface of the heat exchanger to the heating surfaces of the catalyst, generally in the package with accumulating masses, so deep, until it reaches the heating surface of the catalyst.

According to the execution of the invention it is proposed to apply the reducing agent to the catalyst with a stream of flue gas or air through the supply system of a free jet. In the heater, for example, this means that the flow in the, sudestada towards a free jet exiting air flow. Under the "free stream" is meant here the shape of the flow emerging from the nozzle environment, which passes freely through the atmosphere, due to its kinetic energy, i.e., she /environment/comes to the elements of the catalyst is not on special channels or guide elements.

According to a preferred alternative implementation of the inventive method are encouraged to submit a reducing agent to the catalyst inside an airtight system that separates the heat-exchange medium, the replacement of air, flue gas or sewage gas to crude.

Unlike Svobodnoye method of filing in this case, the reducing agent is supplied to the catalyst in a separate channel, which can be created in an advantageous manner the feed direction in the form of a channel located in the radial sealing elements.

When the supply of the reducing agent through a single channel hermetically sealed system, the reducing agent may be added according to the type of partial leaching of the camera. The corresponding cells accumulating masses on the cold opposite surfaces are exempt from the relevant radiant it to the end zone of the catalyst. At the end of the transition stage during which the cell under the influence of a reductant, fully insulated on cold surfaces, the cross section is again released from the sealing element, so that now, for example, the incoming air countercurrent washes away the remaining flue gas and excess reducing agent. When the reducing agent in the catalyst is not exposed on its way coming Wednesday, and in addition to supply of the catalyst by the reducing agent has enough time.

To conduct Svobodnoye process in accordance with the invention serves coplowe device at least one outlet located in both halves of the cap and passing, depending on the circumstances, the total radius of the heat exchanger, and the diversion of/s/ has/have/ slit nozzle; alternatively, the allotment/s/ can/may/ can be equipped by/s/ separate nozzles distributed across the radius of the heat exchanger. Slit nozzle or a number of individual nozzles is located so that the surface of the catalyst in any place will receive an equal amount of reducing agent.

If coplowe the device is made with the possibility of angular adjustment within the same paragraph the area, have beneficial effects on the absorption reductant.

The essence is illustrated by the following drawings in which are shown:

Fig.1 - regenerative heat exchanger with a supply of reductant to the catalyst with a hot surface, made in the form Svobodnoye nozzle device schematic representation in section along line I-I of Fig.-2.

Fig. 2 is a schematical diagram of the regenerative heat exchanger according to Fig.1 in section along line II-II.

Fig.3 is a schematical diagram for comparison with Fig.2; in the context of Dan hood regenerative heat exchanger, nozzle device, in which the channels for the flow are located in radial sealing elements placed between the air and gas sectors.

Fig.4 is a cross section along the line IV-IV of Fig.3 catalyst comprising catalytically active and on top of the storage masses and taprobanica below.

To the regenerative heat exchanger 1 shown in Fig.1 and is designed as a heater, steam boiler /not pictured/ through channel 2 receives hot exhaust gas containing NOx. Hot raw gas G Yes apno circulating catalyst, consisting of the storage masses 3 and under them the additional heat exchanger 4. With two sides, i.e., over a catalyst and under it, i.e., above or below the storage masses 3 or taprobanica 4 is, depending on the circumstances, segment hood 5, 6. Due to the rotation of the catalyst other parts or elements of the storage masses 3 and taprobanica 4 are constantly exposed to the heated gas G, saturated with harmful substances. On the way gas G through the catalytically active accumulating mass recovery NOxinfluenced by adsorption with NH3. At the same time the surface of the heat storage masses 3 and taprobanica 4 are heated with gas G, which is cooled and purified form emerges from the regenerative heat exchanger 1 at its lower end through the channel 7.

The bottom end of the regenerative heat exchanger 1 - i.e., the depicted heater to the cap 6 is connected to the pipe 8, through which towards the canvas gas G is fed clean cold air L going to burning - in the future, just air through the hood 6 to the surface of the heat storage masses 3 or taprobanica 4, heated by gas G. the Air L ohlord the through channel 9 for fire heating.

To restore the NOxas the reductant is injected NH3with transporting heated air through the supply pipe 10 with the heated surfaces of the regenerative heat exchanger 1 through the top cap 5, and thence through coplowe device 11 is supplied to the surface of the heat storage masses 3. Coplowe device 11 depicted in Fig. 1, consists of allotments 13, the inlet tube 10 passing, depending on the circumstances, in the air sector 12 /page Fig.2/ both halves of the cap 5a, 5b to the outer perimeter of the regenerative heat exchanger 1 and having a number of individual openings of the nozzles 14. Alternative outlets 13 can have instead of individual nozzles 14 through the slit nozzle 15 /page Fig.2/. Between the air sectors 12 and gas sectors 17 has a radial sealing elements 16, and from the individual nozzles 14 or slotted nozzles 15, the reducing agent is fed from the conveying air in the form of a free jet in a package for heating surfaces accumulating substances 3 only so deep, until you reach the surfaces of the catalyst, the reducing agent does not fall on the surface of the heating taprobanica 4, in the zone of low temperatures.

For filing vosstanovitelnih radial sealing elements 16a, so it's a closed supply of reductant. Feeding the reducing agent into separate channels 18 of the sealing elements 16a can be strategy the washing chamber, as shown in Fig. 4. The corresponding cell 4a taprobanica on the cold surface of the catalyst is only as exempted from those intended for taprobanica 4 radial sealing elements 16b to the incoming channel 18 of the reducing agent in the leaching of accumulated flue gas moved to the border area of the catalyst (see position 1 in Fig. 4/. After a transitional phase, during which cell 4a, taprobanica under the influence of NH3are isolated on the cold surface 5 /see the position II in Fig.4/, the cross-section taprobanica 4a is released again from the elements 16b /see the position III in Fig.4/, so that now, for example, students in these cell air counter flow washes out the remaining smoke and excess NH3and moves through the channel 11 (see Fig. 1/ for fire heating. This means that the environment does not enter the waste gases, saturated NH3.

1. Method of treatment of waste gases containing harmful Weor waste gases are in heat exchange with another environment, with fixed or circulating accumulating masses, consisting partly of the catalyst, including the supply of reductant from the hot side of the heat exchanger without touching other surfaces directly catalyst separately from exhaust gases containing harmful substances, characterized in that the reducing agent fed to the surface of the heat accumulating mass in such depth, until it reaches the surface of the heating of the catalyst, and the reducing agent is incident on the surface of the heating taprobanica beneath accumulating masses.

2. The method according to p. 1, characterized in that the reducing agent fed to the surface of the heat accumulating mass from a stream of flue gas or air through Svobodnoye nozzle system.

3. Device for treatment of waste gases containing harmful substances, made in the form of a heat exchanger equipped with caps, one of which is placed a tube with at least one outlet located on the radius of the heat exchanger with at least one aperture located on the outlet, for supplying a reducing agent, characterized in that a hole is made in the form of a nozzle.

under item 3, characterized in that the outlet is provided with a separate nozzles distributed along the radius of the heat exchanger.

6. The device according to p. 3, characterized in that the drainage holes are made in the form of the channel formed by the radial sealing elements.

 

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