Flue gas denitration system for deeply adjusting working conditions of coal-fired boiler

Abstract

The invention discloses a coal-fired boiler flue gas denitration system capable of deeply adjusting working conditions, comprising: an internal combustion engine, high-temperature exhaust gas generated by the internal combustion engine entering a flue gas distribution adjusting module; and the flue gas distribution and adjustment module is used for feeding the adjusted flue gas into a tail flue of the boiler, and after the flue gas is mixed with the flue gas of the boiler, the SCR temperature is increased. The whole system is relatively simple in structure, small in equipment investment and maintenance, greatly reduced in operation cost and remarkable in economic benefit.

Description

Technical Field

[0001] The present invention relates to the technical field of internal combustion engines, and in particular to a flue gas denitration system for a coal-fired boiler under deep regulation conditions. Background Art

[0002] Large natural gas internal combustion generator sets play a vital role in the power system and are known for their efficient energy conversion and flexible load regulation characteristics. However, the exhaust gas temperatures generated by these units during operation are extremely high, usually between 300 and 500°C, and contain high concentrations of nitrogen oxides (NOx), about 500 to 800 mg / Nm 3 . There are certain limitations to the existing practices for the treatment of these high-temperature exhaust gases. At present, the following two strategies are mainly adopted for the treatment of exhaust gases from internal combustion engines: one is to directly discharge the high-temperature flue gas into the atmosphere, which not only wastes energy but also burdens the environment; the other is to utilize the heat energy in the exhaust gas by installing waste heat recovery systems, such as waste heat boilers and steam turbine generators. However, due to the limitation of exhaust temperature, the heat recovery efficiency of these systems is not ideal, resulting in a low overall return on investment.

[0003] In addition, the NOx concentration emitted by internal combustion engines far exceeds the national environmental protection standards and must be treated before being discharged. The widely used NOx treatment technology is the selective catalytic reduction (SCR) method, which uses urea or ammonia as a reducing agent to reduce the NOx concentration to below the environmental protection standard. This method requires an expensive SCR catalyst system and consumes a large amount of urea or ammonia during operation. In the deep peak-shaving operation of coal-fired boilers, the flue gas temperature of the SCR system is often lower than the optimal operating temperature, which not only affects the denitrification efficiency, but may also damage the catalyst. Increasing the flue gas temperature of coal-fired boilers under low load has become the key to solving this problem. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides a flue gas denitrification system for a coal-fired boiler under deep regulation to solve the problem of denitrification under deep regulation of coal-fired units and high-concentration NOx emissions in the exhaust gas of internal combustion engines.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a flue gas denitrification system for a coal-fired boiler under deep adjustment conditions, comprising:

[0009] An internal combustion engine, wherein the high-temperature exhaust gas generated by the internal combustion engine enters a flue gas distribution and regulation module;

[0010] The flue gas distribution and regulation module sends the regulated flue gas into the flue duct at the rear of the boiler, mixes with the boiler flue gas and increases the SCR temperature.

[0011] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0012] The tail flue includes a low-temperature economizer, a flue gas monitoring module, an SCR catalyst and an air preheater;

[0013] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0014] The smoke distribution adjustment module is connected to the control module;

[0015] The control module calculates and controls the valve opening in the smoke distribution and adjustment module according to the data provided by the smoke monitoring module and the input of external data;

[0016] The smoke distribution and regulation module performs preliminary distribution of the smoke through a regulating valve.

[0017] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0018] The smoke monitoring module is installed at different outlets of the smoke distribution and regulation module to monitor the temperature and concentration of each smoke channel and provide feedback to the control module to adjust the valve opening.

[0019] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0020] The low-temperature economizer is connected to the SCR catalyst;

[0021] The low-temperature economizer recovers waste heat in the flue gas. After passing through the low-temperature economizer, the flue gas enters the SCR catalyst layer to undergo a denitration reaction.

[0022] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0023] The SCR catalyst is connected to the air preheater;

[0024] The air preheater transfers part of the heat of the flue gas after denitration to the incoming air.

[0025] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0026] The air preheater is connected to the pulverized coal boiler;

[0027] The flue gas treated by the air preheater is returned to the pulverized coal boiler to complete the whole cycle.

[0028] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0029] The smoke distribution and regulation module comprises a plurality of regulating valves for regulating the smoke flow in different areas respectively.

[0030] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0031] The smoke monitoring module monitors the smoke parameters of each partition in real time, including temperature and concentration.

[0032] As a preferred solution of the coal-fired boiler deep adjustment working condition flue gas denitrification system of the present invention, wherein:

[0033] The control module receives data from the flue gas monitoring module and uses an optimization algorithm to calculate the optimal opening setting of each regulating valve.

[0034] Beneficial effects of the present invention: The present invention avoids the waste of energy and pollution to the surrounding environment caused by the direct emission of high-temperature exhaust gas from an internal combustion engine, and greatly improves the energy utilization efficiency of the entire system. In addition, the high-temperature exhaust gas from an internal combustion engine is used to heat the boiler flue gas to meet the temperature requirements of the tail SCR denitrification, and the boiler SCR is used to reduce the NOx in the exhaust gas of the internal combustion engine, and the waste heat of the exhaust gas from the internal combustion engine is recovered by the heating surface at the tail of the boiler, thereby eliminating the NOx purification SCR equipment of the exhaust gas from the internal combustion engine. The structure of the entire system is very simple, the equipment investment and maintenance are very small, the operating costs are greatly reduced, and the economic benefits are significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0036] Figure 1 A model diagram of a flue gas denitrification system for a coal-fired boiler in deep adjustment condition is provided for one embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0040] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0041] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Example 1

[0044] Reference Figure 1, which is an embodiment of the present invention, provides a flue gas denitration system for a coal-fired boiler in a deep adjustment working condition, comprising: an internal combustion engine 100 and a flue gas distribution and adjustment module 500;

[0045] Preferably, the high-temperature exhaust gas generated by the internal combustion engine 100 enters the flue gas distribution and adjustment module 500;

[0046] Preferably, the flue gas distribution and regulation module 500 sends the regulated flue gas into the boiler tail flue 300 to mix with the boiler flue gas to increase the SCR temperature.

[0047] The tail flue 300 includes a low-temperature economizer 301, a flue gas monitoring module 302, an SCR catalyst 303 and an air preheater 304;

[0048] Further, the smoke distribution adjustment module 500 is connected to the control module 400;

[0049] The control module 400 calculates and controls the valve opening in the smoke distribution adjustment module 500 according to the data provided by the smoke monitoring module 302 and the input of external data;

[0050] The smoke distribution and adjustment module 500 performs preliminary distribution of the smoke through the adjustment valve.

[0051] Furthermore, the smoke monitoring module 302 is installed at different outlets of the smoke distribution and adjustment module 500 to monitor the temperature and concentration of each smoke path. These data are used to determine the best smoke distribution plan and provide feedback to the control module to adjust the valve opening.

[0052] Further, the low temperature economizer 301 is connected to the SCR catalyst 303;

[0053] The low-temperature economizer 301 recovers waste heat in the flue gas. After passing through the low-temperature economizer 301, the flue gas enters the SCR catalyst 303 layer to undergo a denitrification reaction.

[0054] Further, the SCR catalyst 303 is connected to the air preheater 304;

[0055] Furthermore, the flue gas passes through the SCR catalyst 303 to remove nitrogen oxides (NOx).

[0056] The air preheater 304 transfers part of the heat of the flue gas after denitrification to the incoming air.

[0057] Further, the air preheater 304 is connected to the pulverized coal boiler 200;

[0058] Furthermore, the flue gas passes through the air preheater 304 to transfer heat to the air used for combustion, thereby improving the combustion efficiency.

[0059] The flue gas treated by the air preheater 304 is returned to the pulverized coal boiler 200 to complete the entire cycle.

[0060] Furthermore, the smoke distribution and regulation module 500 includes a plurality of regulating valves for regulating the smoke flow in different areas respectively.

[0061] Preferably, the smoke distribution adjustment module 500 includes multiple regulating valves, which are adjusted separately. The smoke parameters (temperature and concentration) of the partitioned position are obtained through the smoke monitoring module 302, and the optimization algorithm is used to obtain the best distribution method. The opening of each valve of the smoke distribution adjustment module 500 is adjusted separately to achieve the best overall mixing effect (optimal temperature, optimal concentration).

[0062] Furthermore, the smoke monitoring module 302 monitors the smoke parameters of each partition in real time, including temperature and concentration.

[0063] Furthermore, the control module 400 receives data from the smoke monitoring module 302 and uses an optimization algorithm to calculate the optimal opening setting of each regulating valve, thereby ensuring that the distribution of smoke in each area reaches the optimal state (ie, the temperature and concentration are optimized).

[0064] It should be noted that the high-temperature exhaust gas of the internal combustion engine 100 is sent to the boiler tail flue 300 after adjustment, and its temperature is raised after mixing with the boiler flue gas to meet the reaction temperature requirements of the SCR, and enters the SCR denitrification of the boiler flue gas and the internal combustion engine exhaust. The exhaust temperature of the internal combustion engine is as high as 370°C, and the flue gas temperature before the SCR is about 200°C under the deep adjustment condition of the boiler. By mixing the high-temperature flue gas of the internal combustion engine with the boiler flue gas, the temperature before the SCR reaction is raised to above 260°C, meeting the safe reaction conditions of the SCR. In addition, the waste heat of the internal combustion engine exhaust is also recycled in the tail flue of the coal-fired boiler.

[0065] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0066] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0067] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A coal-fired boiler flue gas denitrification system under deep adjustment condition, characterized in that: include: An internal combustion engine (100), wherein high-temperature exhaust gas generated by the internal combustion engine (100) enters a flue gas distribution and adjustment module (500); A flue gas distribution and adjustment module (500) is provided, wherein the flue gas distribution and adjustment module (500) sends the adjusted flue gas into the boiler tail flue (300), and mixes with the boiler flue gas to increase the SCR temperature.

2. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 1, characterized in that: The tail flue (300) includes a low-temperature economizer (301), a flue gas monitoring module (302), an SCR catalyst (303) and an air preheater (304).

3. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 1 or 2, characterized in that: The smoke distribution adjustment module (500) is connected to the control module (400); The control module (400) calculates and controls the valve opening in the smoke distribution adjustment module (500) according to the data provided by the smoke monitoring module (302) and the input of external data; The smoke distribution and adjustment module (500) performs preliminary distribution of the smoke through an adjustment valve.

4. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 3, characterized in that: The smoke monitoring module (302) is installed at different outlets of the smoke distribution and adjustment module (500), monitors the temperature and concentration of each smoke path, and provides feedback to the control module to adjust the valve opening.

5. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 4, characterized in that: The low-temperature economizer (301) is connected to the SCR catalyst (303); The low-temperature economizer (301) recovers waste heat in the flue gas. After passing through the low-temperature economizer (301), the flue gas enters the SCR catalyst (303) layer to undergo a denitration reaction.

6. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 5, characterized in that: The SCR catalyst (303) is connected to the air preheater (304); The air preheater (304) transfers part of the heat of the flue gas after denitration to the incoming air.

7. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 6, characterized in that: The air preheater (304) is connected to the pulverized coal boiler (200); The flue gas treated by the air preheater (304) is returned to the pulverized coal boiler (200) to complete the entire cycle.

8. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 7, characterized in that: The smoke distribution and regulation module (500) comprises a plurality of regulating valves for respectively regulating the smoke flow rates in different areas.

9. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 8, characterized in that: The smoke monitoring module (302) monitors the smoke parameters of each partition in real time, including temperature and concentration.

10. The deep-adjustment flue gas denitrification system for coal-fired boilers according to claim 9, characterized in that: The control module (400) receives data from the flue gas monitoring module (302) and uses an optimization algorithm to calculate the optimal opening setting of each regulating valve.

Images