RU2603806C2 - Device for cleaning flue gases from nitrogen oxides by selective non-metallic reduction - Google Patents

Abstract

FIELD: energy.

SUBSTANCE: invention relates to heat engineering, more precisely to a device for cleaning flue gases from nitrogen oxides by selective non-metallic reduction. Device includes a flue pipe housing, inside which there is a distribution grid for introduction of ammonia solution inside gas stream of flue gas. Distribution grid is made of rotary segments and is kinematically connected with control unit. Rotary segments are arranged between two circular diaphragms, from which one is tightly connected with chamber for collection o ammonia solution and housing, and other with a guide diffuser. Before flue gas outlet pipe there is an additional cone, conjugated geometrically with guide diffuser and connected with device for movement thereof.

EFFECT: disclosed device provides higher degree of purification of flue gases from nitrogen oxides, is easy to manufacture and reliable in operation.

5 cl, 3 dwg

Description

The invention relates to the chemical purification of flue gases from nitrogen oxides, and more particularly to a device for purifying flue gases from nitrogen oxides by selective non-catalytic reduction, and can be used in power engineering and other industries, including metallurgical and chemical industries.

The main and more dangerous for human health are man-made nitrogen oxides, the main source of emissions of which, in the first place, are transport and heat power engineering. Therefore, purification from them has become not only necessary, but rather inevitable. However, methods for cleaning industrial plants of nitrogen oxides are still ineffective and costly.

A known installation of air purification from gas emissions from industrial enterprises (see patent RU No. 2529218 C1, B0ID 53/00, 2014), including heating and catalytic devices, sorption and filtering devices, a ventilation system and an automatic control system associated with heating elements and a ventilation system, as well as a reagent distribution system and a control system.

However, this installation is not only difficult to implement, but also very expensive during operation. The production of a catalytic device requires special high-tech technology, and during operation it is required to maintain and provide an appropriate mode of heating and cooling it. In addition, their frequent replacement and disposal also requires certain costs.

Another catalytic reactor for cleaning gas emissions from nitrogen oxides using ammonia is known, combined with a spiral countercurrent heat exchanger recuperator (see patent RU No. 2264852, B0IJ 8/02, 2005), in which conventional ammonia is used instead of an expensive and difficult to manufacture catalyst.

However, this device also has a number of disadvantages inherent in the above device, for example, for its normal operation, special tape materials and foam metals are used, as well as special devices for heating and maintaining the temperature strictly in the specified range from 350 ° C to 450 ° C.

The closest set of features to the claimed device is a device for purifying flue gases from nitrogen oxides by a selective non-catalytic reducing agent (see patent RU No. 2200617, B0ID 53/56, 2003), in which a mixture of water vapor and ammonia water through special distribution pipes injected into the stream of purified gaseous products of combustion at its exit from the boiler.

The reasons that impede the achievable technical result indicated below when using a known device adopted as a prototype include the fact that it also, like the devices described above, has a number of disadvantages, namely, it does not fully carry out the process of purifying flue gases from nitrogen oxides. Since the system for introducing and spraying ammonia water with the help of nozzles located on a flat multi-tube grate is ineffective and also unreliable during operation. Some of the lower nozzles will work in the region of the vapor-liquid mixture, while the upper nozzles will definitely be in the region of superheated steam, which will lead to their unstable operation. In addition, to achieve complete evaporation of ammonia water with the help of steam in such a design of a steam collector with any regulator of steam consumption is practically unrealistic. It should also be noted that the condensate formed at the outlet of their nozzles is highly toxic and requires special measures of protection against its impact on all elements of this design. The uniform distribution of ammonia over the cross-section of the gas duct and the length is also practically impossible to achieve, especially when the boiler is operating at its nominal operating mode.

The present invention is to eliminate the above disadvantages of previously known devices for cleaning flue gases from nitrogen oxides by selective non-catalytic reduction.

This problem is solved by achieving a technical result, which consists in creating a new, more efficient, reliable and easy-to-use device for cleaning flue gases from nitrogen oxides by selective non-catalytic reduction.

The specified technical result for the object device is achieved using a known device, including a chimney body, inside which a distribution grid is installed for introducing ammonia solution into the gas flue gas stream and a control unit. The difference of the proposed device is that its distribution grid is made of rotary segments evenly spaced relative to each other in the cross section of the chimney body and movably fixed between two annular diaphragms coaxially mounted in the cylindrical chimney body, while each rotary segment is hydraulically connected to a container for ammonia solution and is kinematically connected with the mechanism of their rotation relative to the longitudinal axis of the chimney body.

The specified technical result for the object device is also achieved by the fact that the inlet and outlet pipes of the chimney body are connected tangentially to it.

The specified technical result for the object device is also achieved by the fact that in the upper part of the chimney body there is a locking element made in the form of a hollow cone mating with a truncated cone of the upper annular diaphragm.

The specified technical result for the object device is also achieved by the fact that a container for collecting the spent ammonia solution is connected to the inner hole of the lower annular diaphragm.

The specified technical result for the object device is also achieved by the fact that the lower annular diaphragm is movably fixed relative to the chimney body along its longitudinal axis.

In the study of the distinguishing features of the claimed device did not reveal any similar known solutions regarding the design of the distribution grid, designed to spray ammonia solution inside the chimney.

The analysis of the prior art by the applicant, including a search by patents and scientific and technical sources of information and identification of sources containing information about analogues of the claimed solution, made it possible to establish that there is no analogue characterized by features that are identical (identical) to all the essential features of the claimed invention.

Therefore, the claimed invention meets the condition of "novelty" under the current law.

To verify the claimed invention, the condition of "inventive step", the applicant conducted an additional analysis of known solutions in order to identify features that match the distinguishing features of the claimed invention. The results of the analysis showed that the claimed invention does not follow from the prior art and could be obtained only with a deep and comprehensive study of this issue.

Therefore, the claimed invention meets the requirement of "inventive step" under applicable law.

The figure 1 shows a General view of a device for cleaning flue gases from nitrogen oxides.

The figure 2 shows a section aa in figure 1.

The figure 3 shows a section bB in figure 2.

Information confirming the possibility of implementing the claimed invention using the specified technical result, are as follows.

The claimed invention is a device for cleaning flue gases from nitrogen oxides by a selective non-catalytic reducing agent, including: a chimney body 1 (Fig. 1), an inlet pipe 2, an outlet pipe 3, a distribution grid of rotary segments 4 and a control unit 5 (conventionally shown in the drawings). In this case, the inlet pipe 2 and the outlet pipe 3 are connected to the chimney body 1 tangentially to its side surface, that is, “tangentially”, and the distribution grid made 4 is located - installed between two annular diaphragms 6, 7 (Fig. 2). A chamber - collector 8 is connected to the upper annular diaphragm 6 for introducing ammonia solution into the distribution grid, which in turn is hermetically connected through the diffuser to the chimney body 1. Above the diffuser 9, a flue gas flow controller 10 geometrically coupled to it is installed coaxially with it. In turn, the lower annular diaphragm 7 is hermetically connected to the chamber 11 for collecting the spent ammonia solution and the chimney body 1. At the same time, the lower diaphragm 7 is resiliently coupled (coupled) with the rotary segments 4 of the distribution grid using elastic elements 12, and axes 13 are installed in each segment 4 (Fig. 3), preventing their spontaneous displacement relative to the holes of the diaphragms 6, 7, but not obstructing their joint rotation relative to each other (the rotation mechanism in the drawing is shown conditionally). This mechanism can be performed by any known method, for example, in the form of a rotary ring kinematically connected with rotary segments 4 and a control device 5. Devices for input and output of spent ammonia solution, as well as the mechanism for moving the regulator 10 (Fig. 2) of the flue gas flow , in the drawings are marked conditionally and can be performed in any known manner, but with the prerequisite for their full and independent automation in the process of their operation.

This device is an integral element in the thermal circuit of the boiler unit and is installed directly at the exit of the flue gases from the boiler, however, this does not exclude other places of its installation, for example, in front of the smoke exhaust or directly in front of the chimney. The device starts automatically with the start-up of the boiler unit and does not require anything except for opening the corresponding flow controllers and metering valves. At the same time, to control the degree of purification of flue gases from nitrogen oxides, you can use traditional controls installed on this unit. However, this does not exclude the use of modern active methods of control and regulation, for example, connecting a special gas analyzer, automatically connected to a computer and included in the control process of the boiler unit itself. The flue gases leaving the boiler unit, depending on the mode of its operation, can differ greatly in both parameters and chemical composition, which will in no way affect the operation of the proposed device if it is equipped with appropriate sensors and connected to the control computer. The degree of their purification in each case will be determined by the selected ratio of the amount of ammonia solution supplied to the amount of harmful impurities — nitrogen oxides in the flue gases. Depending on the capacity of the boiler unit, the number of proposed devices can be installed and more than one, which will favorably affect not only the degree of cleaning, but also the reliability of the boiler unit itself, especially when working in an emergency mode. When flue gases meet with a liquid ammonia solution, they not only clean themselves of nitrogen oxides, but also give off their heat, which is also advisable to use (to increase efficiency) - to return it back to the technological process of the boiler unit. Under the action of the centrifugal component, the vortex flow of the liquid ammonia solution is pressed against the inner surface of the rotary segments 4 (Fig. 3), while the flue gas stream tends to push it away and thereby crushes it into light fractions. With the right ratio of the flow rate of flue gases to the flow rate of ammonia solution, it is easy to achieve their joint crushing to micron size of their particles. As a result of such crushing, the contact area increases, and consequently, the chemical activity of all the ingredients involved in the chemical reactions of this process. The whole process is carried out according to the following scenario. Flue gases through the outlet pipe 3 (Fig. 1) tangentially enter the body 1 of the chimney and swirl in it. After establishing the appropriate gap between the segments 4 (Fig. 3) of the distribution grid, carried out using the device 5, and establishing the necessary gap between the output diffuser 9 and the locking cone of the flue gas flow regulator 10 inside the distribution grid from the chamber 8, a liquid ammonia solution is injected into the vortex flow flue gas. In the interaction of flue gas bubbles with droplets of a liquid ammonia solution, ammonia evaporates and enters into chemical reactions with reagents.

4NH ₃ + 4NO + O ₂ = 4N ₂ + 6H ₂ O

4NH ₃ + 4NO ₂ + O ₂ = 3N ₂ + 6H ₂ O

2NH ₃ + NO ₂ + NO = 3N ₂ + 6H ₂ O

The formed nitrogen molecules together with flue gases through the diffuser 9 enter the outlet pipe 2, and the condensed water together with the spent ammonia solution enters the chamber 11 and then into the regenerator (not shown conventionally in the drawing), and after it is purified and saturated with ammonia, it returns to the collector chamber 8. In this case, in order to maintain optimal parameters (axial and tangential velocities) of the vortex flow in the distribution grid, it is advisable to use the flow controller 10 installed at the output of the differential fusor 9. It is also advisable, in addition to measuring the partial pressure of gases inside the transfer grill, to monitor the chemical composition of the flue gases before and after the device and compare the values with those best parameters that were obtained when debugging this device and recorded in the memory of a computer or gas analyzer. Due to the complexity of the processes and the influence of numerous external factors on the process itself, it is not always possible to determine the optimal value of the degree of purification of flue gases from nitrogen oxides and other inclusions. Therefore, the most reliable means to achieve them are constant monitoring and comparison with the best values obtained during the study and debugging of this device, that is, constant monitoring and its control using a computer.

The technical effect of the use of the invention is as follows:

The proposed device for the purification of flue gases from nitrogen oxides by selective non-catalytic reduction has a low metal consumption, is simple to manufacture and more efficient during operation. The degree of purification from nitrogen oxides of flue gases with its help can be obtained at least 90%. It should be noted that this device is also very effective for trapping any micro suspensions, including solid and aerosol inclusions. From an economic point of view, it is more efficient, reliable and easy to operate. The savings from using this device when burning low-calorie brown coal will be even more significant, and, given the current environmental situation in some regions, its use is more than relevant.

Thus, the above information shows that when using the claimed invention, the following combination of conditions:

- a tool embodying the claimed invention in its implementation, is intended for use in industry, namely in the field of power engineering, in particular as equipment for the purification of flue gases from nitrogen oxides;

- for the claimed invention in the form described in the independent clause of the claims, the possibility of implementation using the methods and methods described above or known prior to the priority date is confirmed;

- means embodying the claimed invention in its implementation, are able to ensure the achievement of the perceived by the applicant technical result.

Therefore, the claimed invention meets the condition of "industrial applicability" under applicable law.

Information sources

1. RF patent No. 2529218 C1, B0ID 53/00, 2014

2. RF patent No. 2264852, B0IJ 8/02, 2005

3. RF patent No. 2200617, B0ID 53/56, 2003.

Claims (5)

1. A device for cleaning flue gases from nitrogen oxides by selective non-catalytic reduction, including a chimney body, inside which a distribution grid is installed for introducing ammonia solution into the flue gas gas stream and a control unit, characterized in that its distribution grid is made of rotary segments evenly spaced relative to each other in the cross section of the chimney body and movably fixed between two annular diaphragms, coaxially mounted in a cylindrical ohm chimney body, with each rotary segment hydraulically connected to the tank for ammonia solution and kinematically connected with the control unit mounted on the chimney body. 2. A device for cleaning flue gases according to claim 1, characterized in that the inlet and outlet pipes of the chimney body are connected tangentially to it. 3. A device for cleaning flue gases according to claim 1, characterized in that in the upper part of the chimney body there is a locking element made in the form of a hollow cone mating with a truncated cone of the upper annular diaphragm. 4. A device for cleaning flue gases according to claim 1, characterized in that a container for collecting spent ammonia solution is connected to the lower opening of the lower annular diaphragm. 5. A device for cleaning flue gases according to claim 1, characterized in that the lower annular diaphragm is movably fixed relative to the chimney body along its longitudinal axis.

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