Water charging system for dry quenching coke boiler

Abstract

This utility model provides a water filling system for a dry quenching coke boiler, including: a demineralized water tank, a deaerator feedwater pump, a heat pipe heat exchanger, a deaerator, a boiler feedwater pump, a dry quenching coke boiler, a boiler feedwater pipeline, and a boiler makeup water pipeline; the boiler feedwater pump and the dry quenching coke boiler are connected in a switchable manner via the boiler feedwater pipeline; the boiler makeup water pipeline is also connected in a switchable manner to the deaerator feedwater pump and the dry quenching coke boiler; the rated working pressure of the deaerator feedwater pump is P1, and the rated working pressure of the boiler feedwater pump is P2, where P1 < P2. On the one hand, it eliminates the need to use a boiler feedwater pump to fill the dry quenching coke boiler, and the rated working pressure of the deaerator feedwater pump is lower than that of the boiler feedwater pump, reducing the risk of water hammer; on the other hand, it eliminates the need to use a temporary filling pump to fill the dry quenching coke boiler, reducing the complexity of the filling operation and the difficulty of manual operation.

Description

Technical Field , ,

[0010] ,

[0009]

[0001] The utility model relates to the technical field of coke dry quenching, in particular to a water filling system for a coke dry quenching boiler. Background Art

[0002] As the core heat exchange equipment of the coke dry quenching waste heat utilization system, the working process of the coke dry quenching boiler is as follows: high-temperature circulating gas (temperature range is 880°C to 960°C) enters the boiler for heat exchange, and after heat exchange, the temperature drops to 160°C to 180°C and is discharged; the boiler absorbs the heat released by the high-temperature gas to generate steam with a pressure range of 3.82 MPa to 13.8 MPa, realizing the effective conversion of waste heat in the high-temperature circulating gas.

[0003] The water filling operation of the coke dry quenching boiler is a key step before its startup or after major overhaul, aiming to establish a normal water level for the coke dry quenching waste heat utilization system and lay a foundation for the subsequent temperature and pressure increase process. However, the designed working pressure and flow rate of the boiler feed pump supporting the coke dry quenching boiler far exceed the actual requirements during the water filling stage. If the boiler feed pump is directly used for water filling, the high-speed water flow will violently squeeze the gas in the pipeline, easily forming a high-pressure shock wave (water hammer effect), resulting in damage to the first valve or instrument connected to the pipeline. Therefore, in on-site operation, a temporary water filling pump has to be additionally configured before each startup of the coke dry quenching boiler. This not only significantly increases the complexity of the water filling operation of the coke dry quenching boiler but also greatly raises the difficulty of manual operation. Summary of the Utility Model

[0004] The purpose of the embodiment of the utility model is to provide a water filling system for a coke dry quenching boiler, which solves the problems of water hammer risk caused by using a boiler feed pump to fill water for the coke dry quenching boiler and the need to additionally set up a temporary water filling pump. The specific technical solution is as follows:

[0005] A water filling system for a coke dry quenching boiler includes:

[0006] A demineralized water tank, a deaeration feed pump, a heat pipe heat exchanger, a deaerator, a boiler feed pump, a coke dry quenching boiler, a boiler feed water pipeline, and a boiler makeup water pipeline; wherein,

[0007] The demineralized water tank, the deaeration feed pump, the heat pipe heat exchanger, the deaerator, the boiler feed pump, and the coke dry quenching boiler are connected in series in sequence;

[0008] The boiler feed pump and the coke dry quenching boiler are connected in a switchable manner through the boiler feed water pipeline;

[0009] The boiler makeup water pipeline is connected to the deaeration feed pump and the coke dry quenching boiler in a switchable manner;

[0010] The rated operating pressure of the deaerator feedwater pump is P1, and the rated operating pressure of the boiler feedwater pump is P2, where P1 < P2.

[0011] In some embodiments, the boiler water supply pipeline includes a boiler water supply pipe, a first valve, and a first check valve;

[0012] The boiler feedwater pipeline connects the deaerator feedwater pump and the dry quenching boiler. The first valve and the first check valve are installed in the boiler feedwater pipeline. The first check valve restricts the flow of water from the dry quenching boiler to the deaerator feedwater pump in the boiler feedwater pipeline.

[0013] In some embodiments, along the direction from the dry quenching boiler to the deaerator feedwater pump, the first check valve and the first valve are sequentially arranged in the boiler feedwater pipeline.

[0014] In some embodiments, the first valve is an electric gate valve or a double gate valve.

[0015] In some embodiments, the nominal diameter of the boiler feedwater pipe is greater than or equal to 80 mm.

[0016] In some embodiments, the boiler feedwater pipeline includes a boiler feedwater pipe, a second valve, and a second check valve;

[0017] The boiler feedwater pipeline connects the boiler feedwater pump and the dry quenching boiler. The second valve and the second check valve are installed in the boiler feedwater pipeline. The second check valve restricts the water flow from the dry quenching boiler to the boiler feedwater pump in the boiler feedwater pipeline.

[0018] In some embodiments, the second valve and the second check valve are sequentially arranged in the boiler feedwater pipeline along the direction from the dry quenching boiler to the boiler feedwater pump.

[0019] In some embodiments, the deoxygenated water pump and the heat pipe heat exchanger are connected by a deoxygenated water supply pipeline.

[0020] The first end of the boiler water supply pipe is directly connected to the deaerator water supply pipe, and the second end of the boiler water supply pipe is directly connected to the boiler water supply pipe.

[0021] The nominal pressure rating of the first valve is greater than or equal to the nominal pressure rating of the second valve;

[0022] The nominal pressure rating of the first check valve is greater than or equal to the nominal pressure rating of the second check valve.

[0023] In some embodiments, the second end of the boiler feedwater pipe is located on the boiler feedwater pipe between the dry quenching boiler and the second one-way valve; or...

[0024] The second end of the boiler water supply pipe is located between the second valve and the second check valve on the boiler water supply pipe.

[0025] In some embodiments, 0.1 ≤ P1 / P2 ≤ 0.25.

[0026] The operation method of the dry quenching coke boiler water filling system provided in this embodiment of the invention is as follows:

[0027] When the dry quenching boiler is operating normally: the boiler makeup water line is shut off, and the boiler feed water line is connected. High-temperature circulating gas (temperature range 880℃ to 960℃) enters the dry quenching boiler for heat exchange, and is cooled to 160℃ to 180℃ before being discharged. The dry quenching boiler absorbs this heat from the high-temperature circulating gas, generating steam with a pressure range of 3.82MPa to 13.8MPa. The steam turbine generator set uses the steam generated by the dry quenching boiler to generate electricity. The condensate cooled after power generation is pumped to the demineralized water tank by the condensate pump. The demineralized water tank is used to desalinate the condensate. The demineralized condensate is then pumped to the heat pipe heat exchanger by the deaerator feed water pump for heating, and then sent to the deaerator for deoxygenation. The deaerated water is then pumped to the dry quenching boiler through the boiler feed water line by the boiler feed water pump to generate steam.

[0028] When a dry quenching coke boiler needs to be filled with water before startup or after major overhaul: connect the boiler water supply line and disconnect the boiler feedwater line. The demineralized water from the demineralized water tank is supplied to the dry quenching coke boiler via the boiler water supply line through the deaerator feedwater pump.

[0029] In this embodiment of the solution, when a water filling operation is required before starting up or after a major overhaul of the dry quenching boiler, a deaerator feedwater pump is used to replenish water to the dry quenching boiler. Compared with the prior art, on the one hand, it is no longer necessary to use a boiler feedwater pump to fill the dry quenching boiler with water. The rated working pressure of the deaerator feedwater pump is lower than that of the boiler feedwater pump, which can reduce the risk of water hammer. On the other hand, it is no longer necessary to use a temporary filling pump to fill the dry quenching boiler with water, which can reduce the complexity of the water filling operation of the dry quenching boiler and reduce the difficulty of manual operation.

[0030] Of course, any product implementing this utility model does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.

[0032] Figure 1 A schematic diagram of the piping system for a dry quenching coke boiler provided in this application embodiment;

[0033] Figure 2 This is a schematic diagram of the piping system for a dry quenching coke boiler water filling system provided in an embodiment of this application.

[0034] The attached figures are labeled as follows:

[0035] Demineralized water tank 10, deaerator feedwater pump 20, heat pipe heat exchanger 30, deaerator 40, boiler feedwater pump 50, dry quenching boiler 60, boiler feedwater pipeline 70, boiler feedwater pipe 71, second valve 72, second check valve 73, boiler makeup water pipeline 80, boiler makeup water pipe 81, first valve 82, first check valve 83, deaerator feedwater pipeline 90, steam turbine generator set 100, condensate pump 110. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art based on this application are within the protection scope of the present utility model.

[0037] In related technologies, directly using a boiler feedwater pump to fill a dry quenching boiler with water can easily generate high-pressure shock waves, resulting in water hammer. Alternatively, a temporary filling pump can be configured to fill the dry quenching boiler with water before each startup, which increases the complexity of the filling operation.

[0038] The purpose of this application is to provide a water filling system for a dry quenching coke boiler, which eliminates the need to use a boiler feedwater pump or a temporary water filling pump to fill the dry quenching coke boiler with water, thereby solving the problem of water hammer risk caused by using a boiler feedwater pump to fill the dry quenching coke boiler with water, as well as the problem of complicated water filling operation caused by setting up an additional temporary water filling pump.

[0039] Therefore, this application proposes a water filling system for a dry quenching coke boiler.

[0040] Figure 1 A schematic diagram of the piping system for a dry quenching coke boiler provided in this application embodiment is shown below. Figure 1 As shown, a dry quenching coke boiler water filling system includes: a demineralized water tank 10, a deaerator feedwater pump 20, a heat pipe heat exchanger 30, a deaerator 40, a boiler feedwater pump 50, a dry quenching coke boiler 60, a boiler feedwater pipeline 70, and a boiler makeup water pipeline 80; wherein, the demineralized water tank 10, the deaerator feedwater pump 20, the heat pipe heat exchanger 30, the deaerator 40, the boiler feedwater pump 50, and the dry quenching coke boiler 60 are connected in series; the boiler feedwater pump 50 and the dry quenching coke boiler 60 are connected in a slewable manner through the boiler feedwater pipeline 70; the boiler makeup water pipeline 80 is slewable in a connection between the deaerator feedwater pump 20 and the dry quenching coke boiler 60. The rated operating pressure of the deaerator feedwater pump 20 is P1, and the rated operating pressure of the boiler feedwater pump 50 is P2, where P1 < P2. In some embodiments, 0.1 ≤ P1 / P2 ≤ 0.25.

[0041] In some embodiments, the operation method of the water filling system for a dry quenching coke boiler is as follows:

[0042] When the dry quenching boiler 60 is operating normally: the boiler makeup water pipeline 80 is disconnected, and the boiler feed water pipeline 70 is connected. High-temperature circulating gas (temperature range 880℃ to 960℃) enters the dry quenching boiler 60 for heat exchange, and is cooled to 160℃ to 180℃ before being discharged. The dry quenching boiler 60 absorbs this heat from the high-temperature circulating gas to generate steam with a pressure range of 3.82MPa to 13.8MPa. The steam turbine generator set 100 uses the steam generated by the dry quenching boiler 60 to generate electricity. The condensate cooled after power generation is pumped to the demineralized water tank 10 by the condensate pump 110. The demineralized water tank 10 is used to desalinate the condensate. The demineralized condensate is pumped to the heat pipe heat exchanger 30 by the deaerator feed water pump 20 for heating, and then sent to the deaerator 40 for deaeration. The deaerated water is pumped to the dry quenching boiler 60 by the boiler feed water pipeline 70 via the boiler feed water pump 50 to generate steam.

[0043] When water filling is required before starting up or after major overhaul of the dry quenching coke boiler 60: connect the boiler water supply line 80 and disconnect the boiler feed water line 70. The demineralized water from the demineralized water tank 10 is supplied to the dry quenching coke boiler 60 via the boiler water supply line 80 through the deaeration feed water pump 20.

[0044] In this embodiment of the solution, when the dry quenching boiler 60 needs to be filled with water before startup or after major overhaul, the deaerator feedwater pump 20 is used to replenish water to the dry quenching boiler 60. Compared with the prior art, on the one hand, it is no longer necessary to use the boiler feedwater pump 50 to fill the dry quenching boiler 60 with water. The rated working pressure of the deaerator feedwater pump 20 is lower than that of the boiler feedwater pump 50, which can reduce the risk of water hammer. On the other hand, it is no longer necessary to use a temporary filling pump to fill the dry quenching boiler 60 with water, which can reduce the complexity of the filling operation of the dry quenching boiler 60 and reduce the difficulty of manual operation.

[0045] The dry quenching coke boiler 60 described in this application embodiment is applicable to conventional dry quenching coke boilers, and is also applicable to integrated dry quenching coke boilers using cyclone primary dust collectors.

[0046] In some embodiments, the boiler water supply pipeline 80 is a pipeline equipped with a valve, thereby enabling the boiler water supply pipeline 80 to be switched on or off.

[0047] In some embodiments, the boiler feedwater pipeline 80 is equipped with both a valve and a check valve. For example, the boiler feedwater pipeline 80 includes a boiler feedwater pipe 81, a first valve 82, and a first check valve 83. The boiler feedwater pipe 81 connects the deaerator feedwater pump 20 and the dry quenching boiler 60. The first valve 82 and the first check valve 83 are located in the boiler feedwater pipe 81. The first check valve 83 restricts the flow of water from the dry quenching boiler 60 to the deaerator feedwater pump 20 within the boiler feedwater pipe 81. When the first valve 82 is opened, the boiler feedwater pipeline 81 provides one-way communication between the deaerator feedwater pump 20 and the dry quenching boiler 60. When the first valve 82 is closed, the communication between the deaerator feedwater pump 20 and the dry quenching boiler 60 is severed.

[0048] When the dry quenching coke boiler 60 is operating normally, the first valve 82 remains closed. The main function of the first check valve 83 is to prevent the high-pressure feedwater delivered to the dry quenching coke boiler 60 by the boiler feedwater pump 50 from flowing back to the low-pressure heat pipe heat exchanger 30 through the boiler water supply pipe 81 when the first valve 82 leaks internally. This can improve the safety of the water filling system of the dry quenching coke boiler 60.

[0049] When the dry quenching coke boiler 60 needs to be filled with water before startup or after major overhaul, the first valve 82 remains open and the boiler water supply pipeline 80 supplies water to the dry quenching coke boiler 60.

[0050] In this configuration, following the flow direction of the medium within the boiler feedwater pipe 81, a first check valve 83 and a first valve 82 are sequentially installed on the boiler feedwater pipe 81. Alternatively, the first check valve 83 and the first valve 82 are sequentially positioned along the direction from the dry quenching boiler 60 to the deaerator feedwater pump 20 within the boiler feedwater pipe 81. When the first valve 82 is closed, the first check valve 83 is not impacted by the high-pressure feedwater supplied from the boiler feedwater pump 50 to the dry quenching boiler 60. In practice, the first check valve 83 has a higher failure rate. Placing the first check valve 83 on the low-pressure side and the first valve 82 on the high-pressure side facilitates the disconnection of the high-pressure side water supply for maintenance should the first check valve 83 fail.

[0051] The first valve 82 can be a gate valve. Specifically, the gate valve can be an electric gate valve, which improves the ease of operation of the first valve 82 through electric control. Specifically, the gate valve can be a double gate valve, which can provide double sealing and better sealing performance, thereby more effectively preventing internal leakage (the high-pressure feedwater delivered by the boiler feedwater pump 50 to the dry quenching boiler 60 flows back to the low-pressure heat pipe heat exchanger 30 through the boiler makeup water pipe 81).

[0052] The nominal diameter of the boiler feedwater pipe 81 is greater than or equal to 80 mm. For example, the nominal diameter DN of the boiler feedwater pipe 81 is any one of 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, or 130 mm, or any value between two values. When the dry quenching coke boiler 60 needs to be filled with water before startup or after major overhaul, the boiler feedwater pipe 81 can provide a suitable water flow rate for the dry quenching coke boiler 60.

[0053] In some embodiments, the boiler feedwater pipeline 70 is a pipeline equipped with a valve, thereby enabling the boiler feedwater pipeline 70 to be switched on or off.

[0054] In some embodiments, the boiler feedwater pipeline 70 is equipped with both a valve and a check valve. For example, the boiler feedwater pipeline 70 includes a boiler feedwater pipe 71, a second valve 72, and a second check valve 73. The boiler feedwater pipe 71 connects the boiler feedwater pump 50 and the dry quenching boiler 60. The second valve 72 and the second check valve 73 are located in the boiler feedwater pipe 71. The second check valve 73 restricts the flow of water from the dry quenching boiler 60 to the boiler feedwater pump 50 within the boiler feedwater pipe 71. When the second valve 72 is opened, the boiler feedwater pipeline 71 establishes a one-way connection between the boiler feedwater pump 50 and the dry quenching boiler 60. When the second valve 72 is closed, the connection between the boiler feedwater pump 50 and the dry quenching boiler 60 is severed.

[0055] During normal operation of the dry quenching coke boiler 60, the second valve 72 remains open, and the boiler feedwater pipeline 70 provides deoxygenated water to the dry quenching coke boiler 60.

[0056] When the dry quenching coke boiler 60 needs to be filled with water before startup or after major overhaul, the second valve 72 is kept closed. The main function of the second check valve 73 is to prevent the makeup water supplied to the dry quenching coke boiler 60 by the deaerator feed water pump 20 from flowing back to the low-pressure heat pipe heat exchanger 30 through the boiler feed water pipeline 71 when the second valve 72 leaks internally, thereby improving the safety of the water filling system of the dry quenching coke boiler 60.

[0057] Specifically, along the direction from the dry quenching coke boiler 60 to the boiler feedwater pump 50, the second valve 72 and the second check valve 73 are sequentially installed in the boiler feedwater pipeline 71.

[0058] The deaerator feedwater pump 20 and the heat pipe heat exchanger 30 are connected via a deaerator feedwater pipe 90. The first end of the boiler feedwater pipe 81 is directly connected to the deaerator feedwater pipe 90, and the second end of the boiler feedwater pipe 81 is directly connected to the boiler feedwater pipe 71. The nominal pressure rating of the first valve 82 is greater than or equal to the nominal pressure rating of the second valve 72. When the dry quenching boiler 60 is operating normally, the closed first valve 82 prevents the high-pressure feedwater supplied by the boiler feedwater pump 50 to the dry quenching boiler 60 from flowing back through the boiler feedwater pipe 81 to the low-pressure heat pipe heat exchanger 30. The nominal pressure rating of the first check valve 83 is greater than or equal to the nominal pressure rating of the second check valve 73. When the dry quenching boiler 60 is operating normally, the first check valve 83 prevents the high-pressure feedwater supplied by the boiler feedwater pump 50 to the dry quenching boiler 60 from flowing back through the boiler feedwater pipe 81 to the low-pressure heat pipe heat exchanger 30.

[0059] In specific implementations, the rated working pressure P1 of the deaerator feedwater pump 20 is selected according to its working requirements, and the rated working pressure P2 of the boiler feedwater pump 50 is selected according to its working requirements. The embodiments of this application are not limited.

[0060] The embodiment of this solution does not use boiler feedwater pump 50 to make water to dry quenching boiler 60, which can effectively reduce the risk of high-pressure shock waves (water hammer) formed by high-speed water flow compressing gas, thereby protecting the safety of pipelines, valves and instruments. Instead, it uses deaerator feedwater pump 20 to make water to dry quenching boiler 60, which fundamentally eliminates the cumbersome operation of configuring temporary water pumps before each start-up of dry quenching boiler 60, and can significantly reduce the difficulty and cost of manual operation.

[0061] Specifically, the second end of the boiler water supply pipe 81 is located on the boiler water supply pipe 71 between the dry quenching boiler 60 and the second one-way valve 73.

[0062] Of course, in practical applications, the connection position between the second end of the boiler makeup water pipe 81 and the boiler feed water pipe 71 is not limited to this. Figure 2 A schematic diagram of the piping system for a dry quenching coke boiler provided in this application embodiment is shown below. Figure 2 As shown, the second end of the boiler water supply pipe 81 is located between the second valve 72 and the second check valve 73 on the boiler water supply pipe 71, which can also achieve the purpose of this application.

[0063] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model are included within the scope of protection of this utility model.

Claims

1. A quenching boiler water charging system, characterized by, include: The system includes a demineralized water tank (10), a deaerator feedwater pump (20), a heat pipe heat exchanger (30), a deaerator (40), a boiler feedwater pump (50), a dry quenching boiler (60), a boiler feedwater pipeline (70), and a boiler makeup water pipeline (80); among which, The demineralized water tank (10), the deoxygenated feed water pump (20), the heat pipe heat exchanger (30), the deaerator (40), the boiler feed water pump (50), and the dry quenching boiler (60) are connected in series. The boiler feed water pump (50) and the dry quenching boiler (60) are connected by the boiler feed water pipeline (70). The boiler water supply pipeline (80) can be switched on and off to connect the deaerator feedwater pump (20) and the dry quenching boiler (60); The rated working pressure of the deaerator water pump (20) is P1, and the rated working pressure of the boiler water pump (50) is P2, where P1 < P2.

2. The water filling system for a dry quenching coke boiler according to claim 1, characterized in that, The boiler water supply pipeline (80) includes a boiler water supply pipe (81), a first valve (82), and a first check valve (83); The boiler water supply pipe (81) connects the deaerator feed water pump (20) and the dry quenching boiler (60). The first valve (82) and the first check valve (83) are installed in the boiler water supply pipe (81). The first check valve (83) restricts the water flow from the dry quenching boiler (60) to the deaerator feed water pump (20) in the boiler water supply pipe (81).

3. The water filling system for a dry quenching coke boiler according to claim 2, characterized in that, Along the direction from the dry quenching coke boiler (60) to the deaerator feedwater pump (20), the first check valve (83) and the first valve (82) are sequentially installed in the boiler water supply pipe (81).

4. The water filling system for a dry quenching coke boiler according to claim 2, characterized in that, The first valve (82) is an electric gate valve or a double gate valve.

5. The water filling system for a dry quenching coke boiler according to claim 2, characterized in that, The nominal diameter of the boiler water supply pipe (81) is greater than or equal to 80 mm.

6. The water filling system for a dry quenching coke boiler according to claim 2, characterized in that, The boiler feedwater pipeline (70) includes a boiler feedwater pipe (71), a second valve (72), and a second check valve (73); The boiler feedwater pipe (71) connects the boiler feedwater pump (50) and the dry quenching boiler (60). The second valve (72) and the second check valve (73) are installed in the boiler feedwater pipe (71). The second check valve (73) restricts the flow of water from the dry quenching boiler (60) to the boiler feedwater pump (50) in the boiler feedwater pipe (71).

7. The water filling system for a dry quenching coke boiler according to claim 6, characterized in that, Along the direction from the dry quenching coke boiler (60) to the boiler feedwater pump (50), the second valve (72) and the second check valve (73) are sequentially installed in the boiler feedwater pipeline (71).

8. The water filling system for a dry quenching coke boiler according to claim 6, characterized in that, The deoxygenated water pump (20) and the heat pipe heat exchanger (30) are connected by a deoxygenated water supply pipe (90); The first end of the boiler water supply pipe (81) is directly connected to the deaerator water supply pipe (90), and the second end of the boiler water supply pipe (81) is directly connected to the boiler water supply pipe (71). The nominal pressure rating of the first valve (82) is greater than or equal to the nominal pressure rating of the second valve (72); The nominal pressure rating of the first check valve (83) is greater than or equal to the nominal pressure rating of the second check valve (73).

9. The water filling system for a dry quenching coke boiler according to claim 8, characterized in that, The second end of the boiler water supply pipe (81) is located on the boiler feed water pipe (71) between the dry quenching boiler (60) and the second one-way valve (73); or, The second end of the boiler water supply pipe (81) is located between the second valve (72) and the second check valve (73) on the boiler water supply pipe (71).

10. The water filling system for a dry quenching coke boiler according to any one of claims 1 to 9, characterized in that, 0.1≤P1 / P2≤0.25.

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