Temperature adjusting air pipeline and waste heat boiler denitration system

Abstract

The utility model discloses a temperature adjusting air pipeline which is used for a waste heat boiler denitration system and comprises a stainless steel pipeline used for conveying high-temperature and high-pressure flue gas between a high-pressure superheater and a high-pressure evaporator to a denitration fan inlet pipeline so that the temperature of flue gas at an outlet of a denitration fan can be increased. The outlet temperature of the ammonia spraying evaporation tank is higher than 235 DEG C; the compensator is arranged on the stainless steel pipeline; and the valve is arranged on the stainless steel pipeline. High-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator is taken, devices such as pumps and the like with the help of external force do not need to be added, natural pressure of the high-temperature and high-pressure flue gas and negative pressure at an inlet of the denitration fan can be used for conveying the flue gas to an inlet pipeline of the denitration fan, and the temperature of flue gas at an outlet of the denitration fan is increased; further, the outlet temperature of the ammonia spraying evaporation tank is higher than 235 DEG C, and ammonium bisulfate crystallization is avoided. The utility model further discloses a waste heat boiler denitration system.

Description

Technical Field

[0001] The utility model relates to the technical field of power generation, in particular to a temperature-adjusting air duct and a waste heat boiler denitration system. Background Art

[0002] The outlet temperature of the ammonia spray evaporator tank of the waste heat boiler of the gas-steam combined cycle unit's denitration system is around 230°C, which is within the crystallization temperature range of ammonium bisulfate, blocking the ammonia spray grid and catalyst, reducing denitration efficiency, increasing ammonia consumption, and affecting the long-term safe and stable operation of the boiler. This problem poses a major hidden danger to the safe operation of the unit.

[0003] After sulfur-containing natural gas is burned, it reacts with ammonia water to generate ammonium bisulfate. At the same time, after passing through the ammonia evaporation tank, the mixed temperature of ammonia water and natural gas is about 220°C, which is below the condensation temperature of ammonium bisulfate, 225°C. The condensed ammonium bisulfate accumulates on the surface of the catalyst, seriously affecting the flow of flue gas, posing a major hidden danger to the safe operation of the unit, causing unplanned shutdown of the unit and serious economic loss.

[0004] The utility model proposes a new solution to the above problems. Utility Model Content

[0005] In order to overcome at least one of the above-mentioned shortcomings, the utility model provides a temperature-adjusting air duct and a waste heat boiler denitration system. The purpose of the utility model can be achieved by adopting the following technical solutions:

[0006] In a first aspect of the present invention, a temperature-adjusting air duct is provided, wherein the temperature-adjusting air duct is used in a waste heat boiler denitration system, comprising:

[0007] The stainless steel pipeline is used to transport the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator to the inlet pipeline of the denitrification fan, so as to increase the flue gas temperature at the outlet of the denitrification fan, thereby making the outlet temperature of the ammonia spray evaporator tank higher than 235℃;

[0008] A compensator, arranged on the stainless steel pipeline;

[0009] The valve is arranged on the stainless steel pipeline.

[0010] In a feasible implementation manner, the temperature-adjusting air duct further includes:

[0011] A heat-insulating component is wrapped around the outside of the stainless steel pipe and is arranged at the inlet of the stainless steel pipe to be used for heat-insulating the high-temperature and high-pressure flue gas at the inlet of the stainless steel pipe.

[0012] In a feasible implementation manner, the thermal insulation component includes an inner protective plate, thermal insulation cotton and an outer protective plate. The thermal insulation cotton is arranged between the inner protective plate and the outer protective plate, and the thickness of the thermal insulation cotton is 200 to 300 mm.

[0013] In a feasible implementation manner, the valve is a manual gate valve, the number of the manual gate valves is two, and a gate valve operating platform is provided below the manual gate valve.

[0014] In a feasible implementation manner, the compensators are arranged on the stainless steel pipeline at intervals, and the distance between two adjacent compensators is 20 to 30 meters. The compensators are corrugated compensators.

[0015] In a feasible implementation manner, the temperature-adjusting air duct further includes: a bracket for guiding and fixing the stainless steel duct.

[0016] In a feasible implementation manner, the bracket includes a fixed bracket and a guide bracket, wherein the pipe clamp of the fixed bracket is tightly held by the stainless steel pipe, and a gap of 4 to 6 mm is provided between the pipe clamp of the guide bracket and the stainless steel pipe.

[0017] In a feasible implementation manner, the temperature-adjusting air duct further includes a stainless steel elbow for changing the direction of the stainless steel duct.

[0018] In a feasible implementation manner, the stainless steel pipe is a DN150 stainless steel pipe.

[0019] A second aspect of the utility model provides a waste heat boiler denitration system, comprising the above-mentioned temperature-adjusting air duct.

[0020] Beneficial technical effects of the utility model: According to the disclosure of the utility model, the temperature-adjusting air duct takes the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator, and does not need to add a pump or other device that relies on external force. It can use the natural pressure of the high-temperature and high-pressure flue gas and the negative pressure at the inlet of the denitrification fan to transport it to the inlet duct of the denitrification fan, so that the temperature of the flue gas at the outlet of the denitrification fan is increased, and then the outlet temperature of the ammonia spray evaporator tank is made higher than 235°C, thereby avoiding the crystallization of ammonium bisulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the accompanying drawings, the following are given by way of example and not limitation:

[0022] Figure 1 The overall structural schematic diagram of the temperature-adjusting air duct of the waste heat boiler denitration system of the embodiment of the utility model is shown.

[0023] Figure 2 A schematic structural diagram of another direction of the temperature-adjusting air duct of the waste heat boiler denitration system of an embodiment of the utility model is shown.

[0024] In the figure: 1. Stainless steel pipe; 2. Compensator; 3. Gate valve; 4. Insulation parts; 401. Inner guard plate; 402. Insulation cotton; 403. Outer guard plate; 5. Gate valve operating platform; 6. Bracket; 601. Fixed bracket; 602. Guide bracket; 7. Denitrification fan inlet pipe. DETAILED DESCRIPTION

[0025] In the following detailed disclosure, these embodiments are fully described with reference to the drawings. In order to make the technical scheme of the utility model more clear and specific to those skilled in the art, the implementation methods described below are not limited to this. The utility model is further described in detail below in combination with the embodiments and drawings.

[0026] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0027] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front" and "back" are based on the directions or positional relationships shown in the accompanying 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 unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0028] like Figure 1-2 As shown, in a first aspect of an embodiment of the utility model, a temperature-adjusting air duct is provided, wherein the temperature-adjusting air duct is used in a waste heat boiler denitration system, comprising:

[0029] The stainless steel pipeline 1 is used to transport the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator to the inlet pipeline of the denitrification fan, so as to increase the flue gas temperature at the outlet of the denitrification fan, thereby making the outlet temperature of the ammonia spray evaporation tank higher than 235°C;

[0030] A compensator 2, arranged on the stainless steel pipeline 1;

[0031] The valve 3 is arranged on the stainless steel pipeline 1.

[0032] The horizontal waste heat boiler heat exchanger is divided into five modules, which are numbered from the engine side. The first-stage module is the superheater module, the second-stage module is the high-pressure evaporator module, the third-stage module is the high-pressure economizer module, the fourth-stage module is the low-pressure economizer module, and the fifth-stage module is the expanded economizer module. In the prior art, the flue gas at the inlet of the denitrification fan is the flue gas of about 310°C between the second-stage high-pressure evaporator module and the third-stage high-pressure economizer module, while the temperature-adjusting air duct provided in the embodiment of the utility model takes the high-temperature flue gas of about 460°C from the first-stage high-pressure superheater module and the second-stage high-pressure evaporator module, and transports it to the inlet of the denitrification fan through the temperature-adjusting air duct. The flue gas temperature and pressure between the first and second stages of the boiler are greater than the flue gas between the second and third stages of the boiler. Therefore, the temperature-regulating air duct of the utility model embodiment takes the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator, and does not need to add a pump or other device that relies on external force. It can utilize the natural pressure of the high-temperature and high-pressure flue gas and the negative pressure at the inlet of the denitrification fan to transport it to the inlet of the denitrification fan, thereby increasing the flue gas temperature at the outlet of the denitrification fan, and further increasing the outlet temperature of the ammonia spray evaporator tank above 235°C, thereby avoiding crystallization of ammonium bisulfate.

[0033] In some embodiments, the temperature-adjusting air duct further includes: a heat-insulating member 4, which is wrapped around the outside of the stainless steel pipe 1 and arranged at the inlet of the stainless steel pipe 1, and is used to insulate the high-temperature and high-pressure flue gas at the inlet of the stainless steel pipe 1. Optionally, the heat-insulating member 4 includes an inner protective plate 401, heat-insulating cotton 402 and an outer protective plate 403, and the heat-insulating cotton 402 is arranged between the inner protective plate 401 and the outer protective plate 403, and the thickness of the heat-insulating cotton 402 is 200-300 mm.

[0034] In this technical solution, the insulation component 4 includes an inner guard plate 401, insulation cotton 402 and an outer guard plate 403, which are used to insulate the high-temperature and high-pressure flue gas at the inlet of the stainless steel pipe 1. The inner guard plate 401 and the outer guard plate 403 are both stainless steel plates. The inner guard plate 401, insulation cotton 402 and the outer guard plate 403 are fixed by bolts. A hole is opened on the insulation component 4 to allow the stainless steel pipe 1 to pass through. The hole position must avoid the bolts fixing the stainless steel plate. The thickness of the insulation cotton is 200-300 mm, preferably 260 mm.

[0035] In some embodiments, the valve 3 is a manual gate valve, the number of the manual gate valves is two, and a gate valve operating platform 5 is provided below the manual gate valve.

[0036] In this technical solution, a manual gate valve is provided on the stainless steel pipe 1 of the temperature-adjusting air duct. The manual gate valve is easy to use and relatively cheap. The provision of two manual gate valves further improves safety.

[0037] In some embodiments, the compensators 2 are arranged on the stainless steel pipeline 1 at intervals, and the distance between two adjacent compensators 2 is 20 to 30 meters. The compensators 2 are corrugated compensators.

[0038] In this technical solution, since the temperature-adjusting air duct transports high-temperature and high-pressure flue gas, a compensator is set on the stainless steel pipe 1. A corrugated compensator can be used. The corrugated compensator is one of the methods to eliminate the expansion and contraction of metal pipes at high temperatures. The corrugated compensator requires an operating temperature of ≥500°C, and plays a role in radial compensation and axial compensation. The setting of the corrugated compensator avoids the axial expansion of the newly installed temperature-adjusting air duct due to heat, and the expansion force is transmitted to the furnace wall and the denitrification fan inlet flue gas duct, causing the furnace wall and the denitrification fan inlet flue gas duct to tear and damage the equipment. The setting of the corrugated compensator should be calculated according to the actual situation of the pipeline to determine its installation position and quantity. Generally speaking, a corrugated compensator needs to be installed every 20 to 30 meters, but the specific spacing needs to be comprehensively considered based on factors such as the thermal expansion and contraction characteristics of the pipeline, working pressure, and temperature changes.

[0039] In some embodiments, the temperature-adjusting air duct further includes: a bracket 6 for guiding and fixing the stainless steel pipe 1. Optionally, the bracket includes a fixed bracket 601 and a guide bracket 602, wherein the pipe clamp of the fixed bracket 601 is locked with the stainless steel pipe 1, and a gap of 4 to 6 mm is provided between the pipe clamp of the guide bracket 602 and the stainless steel pipe 1.

[0040] like Figure 1 The temperature-adjusting air duct shown includes a fixed bracket 601 and a guide bracket 602, wherein there is one fixed bracket 601 and two guide brackets 602. The fixed bracket 601 includes a channel steel and a U-shaped pipe clamp, through which the stainless steel pipe 1 is clamped to the channel steel, and the channel steel and the U-shaped pipe clamp are tightened with nuts; the guide bracket 602 includes a channel steel and a U-shaped pipe clamp, and the U-shaped pipe clamp is fixed to the channel steel by tightening the upper and lower nuts of the channel steel, so that there is a gap of 4 to 6 mm between the U-shaped pipe clamp and the stainless steel pipe 1, and the gap is left so as not to affect the expansion of the stainless steel pipe 1. Specifically, the setting of the fixed bracket 601 makes the pipe have an expansion origin, and the temperature change of the temperature-adjusting air duct caused by each startup of the unit expands with the fixed bracket 601 as the expansion origin. The setting of the guide bracket 602 makes the axial expansion and radial expansion generated with the fixed bracket 601 as the expansion origin guided within a reasonable design range.

[0041] In some embodiments, the temperature-controlled air duct further includes a stainless steel elbow for changing the direction of the stainless steel duct 1 .

[0042] like Figure 1 As shown in the figure, a 90° stainless steel elbow is provided on the temperature-adjusting air duct to change the direction of the temperature-adjusting air duct. Figure 2As shown, a 45° stainless steel elbow is provided on the temperature-adjusting air duct to connect the outlet of the temperature-adjusting air duct with the inlet duct of the denitrification fan.

[0043] In some embodiments, the stainless steel pipe 1 is a DN150 stainless steel pipe.

[0044] In this technical solution, the diameter of the stainless steel pipe 1 ensures that the amount of flue gas transported can not only meet the requirements of increasing the flue gas temperature at the outlet of the denitrification fan, but also ensure that the operating temperature of the denitrification fan does not exceed the limit value, and the air volume also meets the requirements. Under the premise of ensuring the safe and stable operation of the denitrification fan, after the mixed gas passes through the ammonia denitrification evaporation module, it can be guaranteed that the temperature there is controlled above 235°C after reaching the ammonia spray evaporation tank to avoid crystallization of ammonium bisulfate. Specifically, the design goal is to control the temperature after mixing above 235°C. At present, the dilution fan pipeline is 220°C, and the temperature of the temperature control pipeline is 460°C. The temperature after mixing needs to be increased by more than 15°C. The inlet pipe of the dilution fan is DN450. The maximum design flow rate of the wind duct branch is 9m / s. We take 8.8m / s as the design flow rate of the branch. Using the law of thermal conservation, it can be calculated that the mass flow rate of the branch at 460°C is 0.07097kg / s, and the volume flow rate is 0.1557m 3 / s, substituting the design flow rate into the pipe diameter, we get 150mm, so we choose DN150 pipe.

[0045] A second aspect of an embodiment of the utility model provides a waste heat boiler denitration system, wherein the waste heat boiler denitration system comprises the above-mentioned temperature-adjusting air duct.

[0046] like Figure 1-2 As shown, the working process of the temperature-regulating air duct of a waste heat boiler denitration system provided in this embodiment is as follows: the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator of the boiler is taken and transported to the inlet pipe of the denitration fan. After the mixed gas passes through the ammonia denitration evaporation module, the temperature can be controlled above 235°C after reaching the ammonia spray evaporation tank, which significantly reduces the crystallization rate of ammonium bisulfate.

[0047] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0049] In view of the above detailed description, these and other changes can be made to these embodiments, and this written description includes the best mode embodiments to disclose the utility model. The scope of the patent obtained by the utility model is defined by the claims, and the claims are not limited by the content of the present disclosure. The protection scope of the utility model is not limited thereto. Any technician familiar with the technical field within the scope disclosed by the utility model, according to the technical solution and its concept of the utility model, makes equivalent replacement or change, which is within the protection scope of the utility model.

Claims

1. A temperature-adjusting air duct, characterized in that: The temperature-adjusting air duct is used in the waste heat boiler denitration system, and includes: The stainless steel pipeline (1) is used to transport the high-temperature and high-pressure flue gas between the high-pressure superheater and the high-pressure evaporator to the denitration fan inlet pipeline (7), so as to increase the flue gas temperature at the outlet of the denitration fan, thereby making the outlet temperature of the ammonia spray evaporator tank higher than 235° C.; A compensator (2) is arranged on the stainless steel pipeline (1); A valve (3) is arranged on the stainless steel pipeline (1).

2. The temperature-adjusting air duct according to claim 1, characterized in that: The temperature-adjusting air duct also includes: A heat-insulating component (4), the heat-insulating component (4) is wrapped around the outside of the stainless steel pipe (1), and is arranged at the inlet of the stainless steel pipe (1), and is used for heat-insulating the high-temperature and high-pressure flue gas at the inlet of the stainless steel pipe (1).

3. The temperature-adjusting air duct according to claim 2, characterized in that: The thermal insulation component (4) comprises an inner protective plate (401), thermal insulation cotton (402) and an outer protective plate (403); the thermal insulation cotton (402) is arranged between the inner protective plate (401) and the outer protective plate (403); the thickness of the thermal insulation cotton (402) is 200 to 300 mm.

4. The temperature-adjusting air duct according to claim 1, characterized in that: The valve (3) is a manual gate valve, the number of which is two, and a gate valve operating platform (5) is provided below the manual gate valve.

5. The temperature-adjusting air duct according to claim 1, characterized in that: The compensators (2) are arranged at intervals on the stainless steel pipeline (1), and the distance between two adjacent compensators (2) is 20 to 30 meters. The compensators (2) are corrugated compensators.

6. The temperature-adjusting air duct according to claim 1, characterized in that: The temperature-adjusting air duct further comprises: a bracket (6) used for guiding and fixing the stainless steel duct (1).

7. The temperature-adjusting air duct according to claim 6, characterized in that: The support comprises a fixed support (601) and a guide support (602), wherein the pipe clamp of the fixed support (601) is tightly held with the stainless steel pipe (1), and a gap of 4 to 6 mm is provided between the pipe clamp of the guide support (602) and the stainless steel pipe (1).

8. The temperature-adjusting air duct according to claim 1, characterized in that: The temperature-adjusting air duct also includes a stainless steel elbow, which is used to change the direction of the stainless steel duct (1).

9. The temperature-adjusting air duct according to claim 1, characterized in that: The stainless steel pipe (1) is a DN150 stainless steel pipe.

10. A waste heat boiler denitrification system, characterized in that: It comprises the temperature-adjusting air duct as described in any one of claims 1 to 9.

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