SCR (Selective Catalytic Reduction) denitration system for utilizing kiln tail waste heat of cement factory

Abstract

The utility model provides an SCR (Selective Catalytic Reduction) denitration system for utilizing kiln tail waste heat of a cement factory. The SCR denitration system comprises a kiln tail preheater, a waste heat boiler, a tail SCR denitration system, a first fan and a chimney which are communicated in sequence, the waste heat boiler comprises an inlet flue, a boiler high-pressure section, a middle flue, a boiler low-pressure section, a boiler hot water section and an outlet flue which are sequentially communicated from top to bottom. The kiln tail preheater is communicated with the inlet flue through a first air pipe, and the outlet flue is communicated with an air inlet of the tail SCR denitration system through a second air pipe; and a first valve and a second valve are respectively arranged on the first air pipe and the second air pipe. Waste heat flue gas of the kiln tail preheater enters the SCR denitration system after passing through the waste heat boiler, waste heat utilization of a boiler high-pressure section, a boiler low-pressure section and a boiler hot water section is adopted in the waste heat boiler, the waste heat of the kiln tail preheater is utilized to about 180 DEG C, the requirement for low-temperature denitration of the SCR denitration system at 180 DEG C is met, the waste heat recovery rate is increased, and the SCR denitration efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat power generation in cement plants, in particular to an SCR denitration system for utilizing waste heat from a cement plant kiln tail. Background Art

[0002] With the rapid development of the cement industry, "high efficiency, low resistance, energy conservation, and environmental protection" are the innovative design concepts currently pursued in engineering and technical design. The use of SCR denitrification technology in cement plants has become the mainstream process for ultra-low emissions in the industry and is gaining widespread acceptance.

[0003] Cement plants are equipped with waste heat power generation and denitrification processes at the kiln tail. Currently, there are two main technical routes:

[0004] High-temperature and high-dust SCR denitrification: A new SCR denitrification tower is installed between the C1 outlet and the waste heat boiler at the kiln tail. The hot flue gas loses heat through the large and complex flue gas ducts. When it enters the waste heat boiler, its temperature drops by 8-10°C, and waste heat power generation decreases by 2kWh / t.

[0005] High-temperature medium-dust SCR denitrification: A new high-temperature electrostatic precipitator + SCR denitrification tower is installed between the C1 outlet and the waste heat boiler at the kiln tail. The hot flue gas loses heat through the large and complex flue gas duct, and the flue gas temperature at the waste heat boiler inlet is reduced by 10-15°C, reducing waste heat power generation by 3kWh / t.

[0006] The above two technologies themselves have disadvantages such as large footprint, difficult on-site construction, high project cost, complex flue gas ducts, large system resistance, and high power consumption of high-temperature fans.

[0007] In recent years, six-stage preheaters have been widely used in cement kilns. With a six-stage preheater at the kiln tail, the exhaust gas temperature at the C1 drum outlet is around 260°C. Existing waste heat utilization and denitrification systems cannot meet the actual production and operational needs of current cement plants. The waste heat cannot be fully utilized, and the denitrification temperature is outside the normal operating range of the catalyst, resulting in poor denitrification performance and failure to meet denitrification emission standards.

[0008] Therefore, there is an urgent need in the prior art for a technical solution that can not only efficiently utilize the waste heat of the kiln tail exhaust gas while meeting the requirements of the six-stage preheater production process at the kiln tail, but also meet the requirements of a stable denitrification process. Utility Model Content

[0009] The utility model discloses an SCR denitration system for utilizing waste heat from a cement plant kiln, which is used to solve relevant technical problems in the background technology.

[0010] The technical solution provided by the utility model is as follows: an SCR denitrification system for utilizing waste heat at the kiln tail of a cement plant, comprising: a kiln tail preheater, a waste heat boiler, a tail SCR denitrification system, a first fan, and a chimney connected in sequence;

[0011] The waste heat boiler includes: an inlet flue, a high-pressure section of the boiler, an intermediate flue, a low-pressure section of the boiler, a hot water section of the boiler, and an outlet flue, which are connected in sequence from top to bottom;

[0012] The kiln tail preheater is connected to the inlet flue through the first air duct, and the outlet flue is connected to the air inlet of the tail SCR denitrification system through the second air duct;

[0013] The first air duct and the second air duct are respectively provided with a first valve and a second valve.

[0014] In some embodiments, the intermediate flue is connected to the air inlet of the tail SCR denitration system through a third air duct, and a third valve is provided on the third air duct.

[0015] In some embodiments, the kiln tail preheater is connected to the air inlet of the tail SCR denitration system through a fourth air duct, and a fourth valve is provided on the fourth air duct.

[0016] In some embodiments, the dust collector and the second fan are connected between the first fan and the chimney, and the second fan is located close to the chimney.

[0017] In some embodiments, the tail SCR denitration system is connected to the first blower through a fifth air duct.

[0018] In some embodiments, the first fan is connected to the dust collector, the second fan and the chimney in sequence through a sixth air duct.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) The utility model is an SCR denitrification system for utilizing waste heat from the kiln tail of a cement plant. The waste heat flue gas from the kiln tail preheater passes through the waste heat boiler and enters the SCR denitrification system. The waste heat boiler utilizes the waste heat from the high-pressure section, low-pressure section and hot water section of the boiler, and utilizes the waste heat from the kiln tail preheater to about 180°C to meet the low-temperature denitrification of the SCR denitrification system at 180°C, thereby improving both the waste heat recovery rate and the SCR denitrification efficiency.

[0021] (2) The SCR denitrification system of the present invention, which utilizes waste heat from the kiln tail of a cement plant, further adjusts the temperature by setting the third and fourth air ducts, thereby achieving a controllable denitrification temperature range, further satisfying the effect of low-temperature denitrification at 180°C, and further improving the waste heat recovery rate and the efficiency of SCR denitrification.

[0022] (3) In the SCR denitrification system for utilizing waste heat from the kiln tail of a cement plant according to the present invention, the waste heat flue gas from the kiln tail preheater is cleared and settled on the heating surface of the waste heat boiler body, so that the ash content before entering the SCR denitrification system is small and low dust enters, thereby preventing blockage in the SCR denitrification system, improving the use effect of the denitrification system, extending the service life of the denitrification system, and reducing the construction investment cost of the denitrification system and the waste heat recovery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The utility model is a structural schematic diagram of an SCR denitrification system for utilizing waste heat from a cement plant kiln.

[0024] The reference numerals are as follows:

[0025] 1. Kiln tail preheater; 2. First air duct; 3. First valve; 4. Waste heat boiler; 41. Inlet flue; 42. Boiler high-pressure section; 43. Intermediate flue; 44. Boiler low-pressure section; 45. Boiler hot water section; 46. Outlet flue; 5. Second air duct; 6. Second valve; 7. Third air duct; 8. Third valve; 9. Fourth air duct; 10. Fourth valve; 11. Tail SCR denitrification system; 12. Fifth air duct; 13. First fan; 14. Dust collector; 15. Second fan; 16. Sixth air duct; 17. Chimney. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, the utility model is an SCR denitrification system for utilizing waste heat from the kiln tail of a cement plant, comprising: a kiln tail preheater 1, a waste heat boiler 4, a tail SCR denitrification system 11, a first fan 13, and a chimney 17 connected in sequence; wherein, the waste heat boiler 4 comprises: an inlet flue 41, a boiler high-pressure section 42, an intermediate flue 43, a boiler low-pressure section 44, a boiler hot water section 45, and an outlet flue 46 connected in sequence from top to bottom; in this embodiment, the waste heat flue gas from the kiln tail preheater 1 enters the SCR denitrification system after passing through the waste heat boiler 4, and the waste heat boiler 4 utilizes the waste heat of the boiler high-pressure section 42, the boiler low-pressure section 44, and the boiler hot water section 45 to utilize the waste heat of the kiln tail preheater 1 to about 180°C, so as to meet the low-temperature denitrification of the SCR denitrification system at 180°C, thereby improving both the waste heat recovery rate and the SCR denitrification efficiency. Specifically:

[0029] The kiln tail preheater 1 is connected to the inlet flue 41 through the first air duct 2, and the outlet flue 46 is connected to the air inlet of the tail SCR denitration system 11 through the second air duct 5. The tail SCR denitration system 11 is connected to the first fan 13 through the fifth air duct 12, and the first fan 13 is connected to the chimney 17 through the sixth air duct 16. The exhaust gas from the kiln tail preheater 1 has a temperature of about 260°C and enters the waste heat boiler 4 through the first air duct 2. After passing through the boiler high-pressure section 42, the boiler low-pressure section 44, and the boiler hot water section 45 from top to bottom, the temperature drops to The temperature is about 180℃, and then it enters the tail SCR denitration system 11 after passing through the second air duct 5. After denitration is completed, the exhaust gas is extracted by the first fan 13 through the fifth air duct 12 and discharged through the sixth air duct 16 and the chimney 17. The waste heat flue gas from the kiln tail preheater 1 is cleaned and settled on the heating surface of the waste heat boiler 4, so that the ash content before entering the SCR denitration system is small and low dust enters, which prevents blockage in the SCR denitration system, improves the use effect of the denitration system, extends the service life of the denitration system, and reduces the construction investment cost of the denitration system and the waste heat recovery system.

[0030] In this embodiment, the sixth air duct 16 is connected to the dust collector 14 and the second fan 15. The second fan 15 is located near the chimney 17 and is used to extract the flue gas filtered in the dust collector 14 and discharge it through the chimney 17. In this embodiment, the dust collector 14 further purifies the flue gas to prevent the exhaust gas from affecting the environment.

[0031] Example 2

[0032] This embodiment 2 is completed on the basis of embodiment 1, and further controls the temperature of the flue gas entering the tail SCR denitration system 11 through a bypass air adjustment structure. Specifically:

[0033] The intermediate flue 43 is connected to the air inlet of the tail SCR denitrification system 11 through the third air duct 7, and a third valve 8 is provided on the third air duct 7; when the flue gas temperature after passing through the boiler low-pressure section 44 and the boiler hot water section 45 is too low, the third valve 8 is opened to extract part of the flue gas in the intermediate flue 43 and mix it with the flue gas from the outlet flue 46, thereby increasing the intake temperature of the air entering the tail SCR denitrification system 11 and ensuring the denitrification efficiency.

[0034] The kiln tail preheater 1 is connected to the air inlet of the tail SCR denitrification system 11 through the fourth air duct 9, and the fourth air duct 9 is provided with a fourth valve 10; when the flue gas of the outlet flue 46 and the intermediate flue 43 in the waste heat boiler 4 does not reach the operating temperature of the tail SCR denitrification system 11, the fourth valve 10 is opened to extract the flue gas for direct supply or mix it with the flue gas of the outlet flue 46 and the intermediate flue 43, which solves the problem that the exhaust gas temperature is too low under the working condition of the six-stage preheater, affecting the denitrification effect of the catalyst, further adjusts the temperature, realizes the controllable denitrification temperature range, further meets the effect of low-temperature denitrification at 180°C, and further improves the waste heat recovery rate and the efficiency of SCR denitrification.

[0035] Working principle: The exhaust gas from the kiln tail preheater 1 has a temperature of about 260°C. It enters the waste heat boiler 4 through the first air duct 2. After passing through the boiler high-pressure section 42, boiler low-pressure section 44, and boiler hot water section 45 from top to bottom, the temperature drops to about 180°C. After passing through the second air duct 5, it enters the tail SCR denitration system 11.

[0036] When the flue gas temperature after passing through the boiler low-pressure section 44 and the boiler hot water section 45 is too low, the third valve 8 is opened to extract part of the flue gas in the intermediate flue 43 and mix it with the flue gas from the outlet flue 46 to increase the intake temperature of the air entering the tail SCR denitrification system 11;

[0037] When the flue gas from the outlet flue 46 and the intermediate flue 43 of the waste heat boiler 4 does not reach the operating temperature of the tail SCR denitrification system 11, the fourth valve 10 is opened to extract the flue gas for direct supply or to mix it with the flue gas from the outlet flue 46 and the intermediate flue 43;

[0038] After denitration is completed, the exhaust gas is drawn out by the first fan 13 through the fifth air duct 12, filtered by the dust collector 14, and then drawn out by the second fan 15 through the sixth air duct 16 and the chimney 17.

[0039] In this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0040] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An SCR denitrification system for utilizing waste heat from a cement plant kiln, characterized in that: include: A kiln tail preheater (1), a waste heat boiler (4), a tail SCR denitrification system (11), a first fan (13), and a chimney (17) are sequentially connected; The waste heat boiler (4) comprises: an inlet flue (41), a boiler high-pressure section (42), an intermediate flue (43), a boiler low-pressure section (44), a boiler hot water section (45), and an outlet flue (46) which are sequentially connected from top to bottom; The kiln tail preheater (1) is connected to the inlet flue (41) through a first air duct (2), and the outlet flue (46) is connected to the air inlet of the tail SCR denitration system (11) through a second air duct (5); The first air duct (2) and the second air duct (5) are respectively provided with a first valve (3) and a second valve (6).

2. The SCR denitrification system for utilizing waste heat from a cement plant kiln as claimed in claim 1, characterized in that: The intermediate flue (43) is connected to the air inlet of the tail SCR denitration system (11) through a third air duct (7), and a third valve (8) is provided on the third air duct (7).

3. The SCR denitrification system for utilizing waste heat from a cement plant kiln as claimed in claim 1, characterized in that: The kiln tail preheater (1) is connected to the air inlet of the tail SCR denitration system (11) through a fourth air duct (9), and a fourth valve (10) is provided on the fourth air duct (9).

4. The SCR denitrification system for utilizing waste heat from a cement plant kiln as claimed in claim 1, characterized in that: The first fan (13) and the chimney (17) are connected to a dust collector (14) and a second fan (15), and the second fan (15) is located close to the chimney (17).

5. The SCR denitrification system for utilizing waste heat from a cement plant kiln as claimed in claim 1, characterized in that: The tail SCR denitration system (11) is connected to the first blower (13) via a fifth air duct (12).

6. The SCR denitrification system for utilizing waste heat from a cement plant kiln as claimed in claim 4, characterized in that: The first fan (13) is connected to the dust collector (14), the second fan (15) and the chimney (17) in sequence through a sixth air duct (16).

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