Regulating system for steam flow split-range control for flue gas denitration of thermal power peak regulation unit and denitration system

Abstract

The utility model belongs to the technical field of ammonia preparation through hydrolysis of urea instead of liquid ammonia of a peak shaving unit, and particularly relates to a regulating system for steam flow split-ranging control for flue gas denitration of a thermal power peak shaving unit and a denitration system. The adjusting system at least comprises a medium-pressure steam pipeline; the first steam regulating valve and the second steam regulating valve are arranged in parallel, and the first steam regulating valve and the second steam regulating valve are respectively communicated with the medium-pressure steam pipeline; the temperature and pressure reducer is communicated with the first steam regulating valve and the second steam regulating valve; and the hydrolyzer is communicated with the temperature and pressure reducer. According to the utility model, the two pneumatic control valves are connected in parallel to replace a single pneumatic control valve commonly used by a temperature and pressure reducing device, so that a proper amount of temperature and pressure reducing steam can be provided for a downstream hydrolyzer according to steam quality fluctuation and ammonia consumption change caused by different loads of a boiler, and safe production and up-to-standard emission are ensured.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of peak regulation unit liquid ammonia is changed into urea hydrolysis ammonia technology, specifically relates to a kind of for the steam flow control of flue gas denitrification of thermal power peak regulation unit, and the adjusting system and denitrification system of control. BACKGROUND

[0002] Flue gas of thermal power generation and petrochemical industry needs to be treated by denitrification, and after being reduced into N2, NOx is discharged into atmosphere, and the denitrification reducing agent is generally liquid ammonia and urea. Since liquid ammonia has significant safety hazards, the reducing agent is currently mostly urea.

[0003] Urea decomposition ammonia includes urea pyrolysis technology and urea hydrolysis technology, and urea hydrolysis technology can be divided into urea ordinary hydrolysis and catalytic hydrolysis technology. Among them, urea pyrolysis process is gradually replaced by urea hydrolysis ammonia technology due to high energy consumption, high operating cost, low urea decomposition rate, easy plugging of tail pipeline and high failure rate.

[0004] Ordinary hydrolysis has slow response speed, while catalytic hydrolysis ammonia can shorten the response time of urea hydrolysis to ammonia demand signal to within 5-30s. When the ammonia demand of unit increases, urea hydrolysis ammonia can respond in time, and NOx emission exceeding standard caused by delayed ammonia supply basically does not occur.

[0005] Stable preparation and supply of hydrolyzer finished gas are the key to denitrification, which involves two important equipment: pressure reducing device and hydrolyzer. The currently used pressure reducing device has the following common problems, which seriously affect the operation safety and the stable supply of reducing agent, so as to ensure the denitrification efficiency:

[0006] 1. Safety valve jump. The safety valve is located on the outlet pipeline of the pressure reducing device, and its set pressure is usually slightly higher than the inlet steam pressure requirement of the downstream hydrolyzer. The hydrolyzer itself has a certain storage capacity, when the internal hydrolysis finished gas is sufficient, the steam inlet valve will be closed for a short time without the need of pressure reducing steam to provide heat, and the regulating valve cannot act in time, resulting in pipe pressure and safety valve jump.

[0007] 2. The type selection of regulating valve is not suitable. According to different steam quality, the scouring of steam needs to be considered to prevent valve plate corrosion, wear and other conditions, which leads to valve sealing, steam leakage. The condition of regulating valve body leads to internal leakage or lower than regulating range, which may also cause frequent jump of safety valve.

[0008] 3. The regulating valve cannot adapt to the steam quality and flow fluctuation of the peak shaving unit. Especially when there are two boilers, the desuperheater may face the situation that both boilers are running at full load and the required steam flow is 3.2t / h, or only one boiler is running at 30% load and the required steam flow is only 400kg / h. The large regulating valve runs at a small opening or the small regulating valve runs at a large opening, which will produce noise, vibration and over-regulation, and cannot be stably controlled. Utility model content

[0009] To solve the problems in the prior art, the utility model provides a kind of regulating system and denitration system for steam flow split range control of thermal power peak shaving unit flue gas denitration.The utility model can guarantee that the steam flow of desuperheater outlet adapts to the output of hydrolyzer under different loads, and downstream hydrolyzer can be stably operated, and it is suitable for various thermal power peak shaving units or frequent load fluctuation.

[0010] The technical scheme provided by the utility model is as follows:

[0011] A kind of regulating system for steam flow split range control of thermal power peak shaving unit flue gas denitration, at least includes:

[0012] Middle-pressure steam pipeline;

[0013] First steam regulating valve and second steam regulating valve in parallel, the first steam regulating valve and the second steam regulating valve are communicated with the middle-pressure steam pipeline respectively;

[0014] Desuperheater, which is communicated with the first steam regulating valve and the second steam regulating valve;

[0015] And hydrolyzer communicated with the desuperheater.

[0016] Due to the change of peak shaving condition and downstream steam demand, the steam flow of system can exist great fluctuation.The above technical scheme adopts the way of two steam regulating valves in parallel for steam flow split range control, can make each steam regulating valve work at the highest regulating precision, to adapt to the condition of large range fluctuation.

[0017] Further, desuperheater inlet orifice plate flowmeter is arranged on the communication pipeline between the middle-pressure steam pipeline and each steam regulating valve, and the desuperheater inlet orifice plate flowmeter, the first steam regulating valve and the second steam regulating valve are connected with the same controller respectively.

[0018] Based on the above technical scheme, interlocking of desuperheater inlet orifice plate flowmeter, first steam regulating valve and second steam regulating valve can be realized, so as to adjust the flow of each steam regulating valve according to the change of system flow.

[0019] Furthermore, a pneumatic switch valve for the hydrolyzer inlet is provided on the connecting pipe between the desuperheater and the hydrolyzer, and the pneumatic switch valve for the hydrolyzer inlet, the first steam regulating valve, and the second steam regulating valve are respectively connected to the same controller.

[0020] Based on the above technical solution, the first steam regulating valve, the second steam regulating valve and the pneumatic switch valve at the hydrolyzer inlet can be interlocked. When the pneumatic switch valve at the hydrolyzer inlet is closed, the first steam regulating valve and the second steam regulating valve are closed.

[0021] Furthermore, a pneumatic switch valve for the desuperheater and pressure regulator is installed on the connecting pipeline between the inlet orifice plate flow meter of the desuperheater and pressure regulator and each steam regulating valve, and a remote pressure gauge for the outlet of the desuperheater and pressure regulator is installed on the connecting pipeline between the desuperheater and pressure regulator and the pneumatic switch valve for the inlet of the hydrolyzer. The pneumatic switch valve for the desuperheater and pressure regulator and the remote pressure gauge for the outlet of the desuperheater and pressure regulator are respectively connected to the same controller.

[0022] Based on the above technical solution, the interlock between the pneumatic switch valve of the desuperheater and the remote pressure gauge at the outlet of the desuperheater can be realized. When the outlet pressure of the desuperheater is higher than the set pressure of the safety valve, the pneumatic switch valve of the desuperheater is shut off.

[0023] Furthermore, a desuperheating and pressure reducing device check valve and a desuperheating and pressure reducing device manual shut-off valve are sequentially connected between the desuperheating and pressure reducing device inlet orifice plate flow meter and each steam regulating valve.

[0024] Furthermore, the desuperheating and pressure reducing device is also equipped with a desuperheating and pressure reducing device safety valve.

[0025] Specifically, the rated flow rates of the first steam regulating valve and the second steam regulating valve may be the same or different.

[0026] Based on the above technical solution, different flow regulation requirements can be adapted by combining two steam regulating valves, and each steam regulating valve can operate at the highest regulation accuracy.

[0027] This utility model also provides a denitrification system, including the aforementioned steam flow range control regulating system for denitrification of flue gas in thermal power peak-shaving units. The medium-pressure steam pipeline is connected to the boiler's medium-pressure steam pipeline, and the hydrolyzer is connected to the boiler's SCR denitrification device.

[0028] Specifically, the first steam regulating valve is open, and the second steam regulating valve is closed.

[0029] Specifically, the first steam regulating valve is closed, and the second steam regulating valve is open.

[0030] Specifically, both the first steam regulating valve and the second steam regulating valve are open.

[0031] According to the technical scheme, each steam regulating valve can work independently or simultaneously to meet system fluctuation.

[0032] In the technical scheme, each steam regulating valve is made of hard alloy or above, including A217 WC6 / A216 WCC, and is suitable for medium-pressure steam to prevent internal leakage of the valve and ensure service life.

[0033] The regulating valve should meet five-grade leakage or above.

[0034] The two regulating valves should be able to realize 0-100% opening degree adjustment.

[0035] The beneficial effects of the utility model are as follows:

[0036] 1. The steam flow can be adapted to various peak shaving conditions.

[0037] 2. The safety and stability of the entire denitration system can be improved. DETAILED DESCRIPTION

[0038] Figure 1 is a system diagram of the regulating system for steam flow split-range control of flue gas denitration of a thermal power peak shaving unit provided by the utility model.

[0039] Figure 2 is a principle diagram of a steam system of a liquid ammonia to urea hydrolysis ammonia preparation part of the peak shaving unit.

[0040] ATTACHED Figure 1 , 2 In the technical scheme, the structure represented by each reference numeral is listed as follows:

[0041] 1. A pneumatic on-off valve of an attemperator; 2. A check valve of the attemperator; 3. A manual stop valve of the attemperator; 4. A first steam regulating valve; 5. A second steam regulating valve; 6. An attemperator; 7. A safety valve of the attemperator; 8. A pneumatic on-off valve of a hydrolyzer inlet; 9. A hydrolyzer; 10. An inlet orifice plate flowmeter of the attemperator; 11. An outlet remote pressure gauge of the attemperator; and 12. A medium-pressure steam pipeline. DETAILED DESCRIPTION

[0042] The principle and features of the utility model are described as follows, and the examples are only used to explain the utility model and are not used to limit the scope of the utility model.

[0043] It should be noted that when a part or component is considered to be "connected to," "located on," or "assembled" to another part or component, it can be directly mounted on the other part or component, or it may be located in an intermediate part or component. The terms "left," "right," "upper," "lower," and similar expressions used in this document are for illustrative purposes only.

[0044] Example 1

[0045] like Figure 1 As shown, the steam flow range control system for flue gas denitrification in thermal power peak-shaving units includes: a medium-pressure steam pipeline 12; a first steam regulating valve 4 and a second steam regulating valve 5 connected in parallel; a desuperheater and pressure reducer 6; and a hydrolyzer 9 connected to the desuperheater and pressure reducer 6. The first steam regulating valve 4 and the second steam regulating valve 5 are respectively connected to the medium-pressure steam pipeline 12. The desuperheater and pressure reducer are connected to the first steam regulating valve 4 and the second steam regulating valve 5. The desuperheater and pressure reducer 6 may be equipped with a desuperheater and pressure reducer safety valve 7.

[0046] This technical solution uses two pneumatic regulating valves in parallel to replace the single pneumatic regulating valve commonly used in desuperheating and pressure reducing devices. It can provide the downstream hydrolyzer with an appropriate amount of desuperheating and pressure reducing steam according to the steam quality fluctuations and ammonia consumption changes caused by different boiler loads, ensuring safe production and compliance with emission standards.

[0047] Example 2

[0048] Based on Example 1, such as Figure 1 As shown, a desuperheater / pressure regulator inlet orifice flow meter 10 is installed on the connecting pipe between the medium-pressure steam pipeline 12 and each steam regulating valve. A desuperheater / pressure regulator pneumatic switch valve 1, a desuperheater / pressure regulator check valve 2, and a desuperheater / pressure regulator manual shut-off valve 3 are sequentially connected on the connecting pipe between the desuperheater / pressure regulator inlet orifice flow meter 10, the first steam regulating valve 4, and the second steam regulating valve 5. The desuperheater / pressure regulator inlet orifice flow meter 10, the first steam regulating valve 4, and the second steam regulating valve 5 are all connected to the same controller for interlocking.

[0049] A pneumatic inlet valve 8 for the hydrolyzer is installed on the connecting pipe between the desuperheater / pressure reducer 6 and the hydrolyzer 9. A remote pressure gauge 11 for the desuperheater / pressure reducer outlet is installed on the connecting pipe between the desuperheater / pressure reducer 6 and the pneumatic inlet valve 8 for the hydrolyzer 9. The pneumatic inlet valve 8, the first steam regulating valve 4, and the second steam regulating valve 5 are all connected to the same controller for interlocking. The pneumatic inlet valve 1 and the remote pressure gauge 11 for the desuperheater / pressure reducer outlet are also connected to the same controller for interlocking.

[0050] Each controller can be the same controller.

[0051] Example 3

[0052] On the basis of the above embodiments, as shown in Figure 1 , 2 A denitration system includes a regulating system for steam flow split control of flue gas denitration of a thermal power peak regulation unit, wherein the medium-pressure steam pipeline 12 is connected to a medium-pressure steam pipeline of a boiler, and the hydrolyzer 9 is connected to an SCR denitration device of the boiler.

[0053] In the technical solution, the hydrolysis reaction of the hydrolyzer uses boiler steam as a heat source. After the boiler steam passes through the desuperheater and pressure reducer, the steam quality at the outlet of the hydrolyzer can be ensured, and the hydrolyzer can be used to catalytically hydrolyze urea to prepare ammonia.

[0054] In other embodiments, a pressure gauge, a thermometer, or the like can be arranged before the desuperheater inlet orifice plate flowmeter 10. A thermometer, a pressure gauge, or the like can be arranged before the desuperheater outlet remote transmission pressure gauge 11.

[0055] Example 1

[0056] The denitration system of Example 3 is adopted, and the regulating system for steam flow split control of flue gas denitration of a thermal power peak regulation unit of Example 2 is adopted:

[0057] The medium-pressure steam quality of the boiler is 3.6 MPa, and the temperature is 325°C.

[0058] The first steam regulating valve has a parameter of DN50 and an opening degree of 77%.

[0059] The second steam regulating valve has a parameter of DN20 and an opening degree of 80%.

[0060] The steam quality at the outlet of the hydrolyzer is 0.7 MPa, about 165°C, and the flow is 3270 kg / h.

[0061] Comparative Example 1

[0062] The denitration system of Example 3 is adopted, and the regulating system for steam flow split control of flue gas denitration of a thermal power peak regulation unit of Example 2 is adopted, and the difference is that a single small steam regulating valve is used when the steam consumption is small:

[0063] The medium-pressure steam quality of the boiler is 0.96 MPa, and the temperature is 280°C.

[0064] The single steam regulating valve has a parameter of DN20 and an opening degree of 65%.

[0065] The steam quality at the outlet of the hydrolyzer is 0.7 MPa, about 165°C, and the flow is 400 kg / h.

[0066] Comparative Example 2

[0067] The denitration system of example 3 is adopted, and the adjusting system of example 2 for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit is adopted, with the difference that a single large steam adjusting valve is adopted when the steam consumption is at the medium flow rate:

[0068] The medium-pressure steam quality in the boiler is 2Mpa, and the temperature is 300℃;

[0069] The single steam adjusting valve parameter is DN50, and the opening is 53%;

[0070] The hydrolyzer outlet steam quality is 0.7MPa, about 165℃, and the flow rate is 1900kg / h.

[0071] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any form; any person skilled in the art can implement the present application according to the drawings and the above; however, any equivalent changes, modifications and evolutions made by those skilled in the art within the scope of the technical scheme of the present application, using the disclosed technical content, are equivalent embodiments of the present application; meanwhile, any equivalent changes, modifications and evolutions made according to the essential technology of the present application to the above embodiments are still within the protection scope of the technical scheme of the present application.

Claims

1. A regulating system for steam flow split range control of flue gas denitration of a thermal power peak shaving unit, characterized in that, At least comprising: a medium pressure steam pipeline (12); a first steam regulating valve (4) and a second steam regulating valve (5) arranged in parallel, the first steam regulating valve (4) and the second steam regulating valve (5) being communicated with the medium pressure steam pipeline (12) respectively; a desuperheater (6) communicated with the first steam regulating valve (4) and the second steam regulating valve (5); and a hydrolyzer (9) communicated with the desuperheater (6).

2. The regulating system for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit according to claim 1, characterized in that: A desuperheater inlet orifice plate flowmeter (10) is arranged on the communication pipeline between the medium pressure steam pipeline (12) and each steam regulating valve, the desuperheater inlet orifice plate flowmeter (10), the first steam regulating valve (4) and the second steam regulating valve (5) being connected with the same controller respectively.

3. The regulating system for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit according to claim 2, characterized in that: A hydrolyzer inlet pneumatic on-off valve (8) is arranged on the communication pipeline between the desuperheater (6) and the hydrolyzer (9), the hydrolyzer inlet pneumatic on-off valve (8), the first steam regulating valve (4) and the second steam regulating valve (5) being connected with the same controller respectively.

4. The regulating system for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit according to claim 3, characterized in that: a desuperheater pneumatic on-off valve (1) is arranged on the communication pipeline between the desuperheater inlet orifice plate flowmeter (10) and each steam regulating valve; a desuperheater outlet remote pressure gauge (11) is arranged on the communication pipeline between the desuperheater (6) and the hydrolyzer inlet pneumatic on-off valve (8); the desuperheater pneumatic on-off valve (1) and the desuperheater outlet remote pressure gauge (11) are connected with the same controller respectively.

5. The regulating system for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit according to claim 4, characterized in that: a desuperheater check valve (2) and a desuperheater hand-operated stop valve (3) are arranged in sequence on the communication pipeline between the desuperheater inlet orifice plate flowmeter (10) and each steam regulating valve; the desuperheater (6) is further provided with a desuperheater safety valve (7).

6. The regulating system for steam flow split-range control of flue gas denitration of a thermal power peak-shaving unit according to any one of claims 1 to 5, characterized in that: The rated flow of the first steam regulating valve (4) and the second steam regulating valve (5) is the same or different.

7. A denitration system characterized by comprising: The regulating system according to any one of claims 1 to 6, wherein the medium pressure steam pipeline (12) is communicated with a boiler medium pressure steam pipeline, and the hydrolyzer (9) is communicated with a boiler SCR denitration device.

8. The deNOx system according to claim 7, characterized by: The first steam regulating valve (4) is opened, and the second steam regulating valve (5) is closed.

9. The denitration system according to claim 7, characterized in that: The first steam regulating valve (4) is closed, and the second steam regulating valve (5) is opened.

10. The denitration system according to claim 7, characterized in that: Both the first steam regulating valve (4) and the second steam regulating valve (5) are opened.

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