Boiler device

Abstract

To provide a boiler device capable of surely preventing a situation in which a water level is abnormally low or carry-over occurs in a can without generating a large pressure loss or without unnecessarily raising a steam pressure of a boiler.SOLUTION: A porous orifice 18 for preventing occurrence of disturbance such as load fluctuation or pressure fluctuation of a boiler 11 is provided in a steam supply pipe 12 from the boiler 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a boiler device, and particularly to a so-called small-sized boiler device.

Background Art

[0002] In a small-sized boiler device with a steam generation amount of about 500 to 10,000 kg / h, since the amount of water held is small, the water level in the boiler may fluctuate greatly up and down due to disturbances such as sudden load fluctuations and sudden pressure fluctuations. Along with this fluctuation, there is a risk of falling into abnormal states such as the water level in the boiler becoming abnormally low or carry-over occurring where the water in the boiler overflows from the boiler.

[0003] For countermeasures against these, an orifice is provided between the boiler and the main steam valve installed for the purpose of controlling the steam flow rate in the steam supply pipe to the steam supply destination. In the known art, a single-hole orifice is used as this type of orifice. As a boiler device in which an orifice is provided in the steam supply pipe, the one described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a single-hole orifice, the pressure loss is large, and therefore there is a high risk of affecting the steam supply amount to the load side. Therefore, as further countermeasures, there are problems such as the need to set the steam pressure of the boiler high.

[0006] Therefore, the present invention solves such problems, and in a boiler device, without generating a large pressure loss and without making the steam pressure of the boiler higher than necessary, it is possible to surely prevent the water level in the can from becoming abnormally low or carryover from occurring.

Means for Solving the Problems

[0007] To achieve this object, the boiler device of the present invention is provided with a porous orifice for preventing the occurrence of disturbances such as load fluctuations and pressure fluctuations regarding the boiler in the steam supply pipe leading from the boiler. Supply steam to the load in the steam supply pipe At the steam inflow end from the boiler in, a main steam valve for controlling the steam flow rate from the boiler is connected, and the A porous orifice for preventing the occurrence of disturbances such as load fluctuations and pressure fluctuations regarding the boiler is provided. At the end of the valve box of the main steam valve between the boiler and the main steam valve It is characterized in that it is provided.

[0008] According to the boiler device of the present invention, it is preferable that the minimum diameter of the orifice hole is in the range of 3.0 mm to 7.0 mm.

Effects of the Invention

[0011] According to the boiler device of the present invention, due to the provision of the orifice, even when disturbances such as sudden load fluctuations and sudden pressure fluctuations occur, it is possible to prevent the water level in the can from fluctuating greatly up and down. Moreover, since the orifice is a porous orifice, the pressure loss can be made smaller than that of a single-hole orifice. Therefore, compared with a single-hole orifice having a large pressure loss, the risk of affecting the steam supply amount to the load side is low. Also, for this reason, even without setting the steam pressure of the boiler high, it is possible to prevent the water level in the can from fluctuating significantly up and down.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] In the boiler device according to the embodiment of the present invention shown in FIG. 1, 11 is a small boiler, and the steam generation amount is set to an arbitrary amount in the range of 500 to 10,000 kg / h. And 12 is a steam supply pipe for supplying steam from the boiler 11 to a load (not shown). The steam supply pipe 12 is connected to a steam header 13. The steam header 13 is for distributing the generated steam toward each load, and in the illustrated example, a plurality of distribution pipes 14 are connected. Each distribution pipe 14 is provided with a distribution valve 15 respectively. An inflow valve 16 is connected to the steam inflow end portion in the steam header 13. Also, a main steam valve 17 for controlling the steam flow rate from the boiler 11 is connected to the steam outflow end portion from the boiler 11 in the steam supply pipe 12.

[0014] In the boiler device shown in FIG. 1, a porous orifice 18 is provided between the boiler 11 and the main steam valve 17. Specifically, in the boiler device shown in FIG. 1, the porous orifice 18 is directly attached to the end portion of the valve box of the main steam valve 17.

[0015] Figure 2 shows an example of the structure of the porous orifice 18. As shown in the figure, three circles 22, 23, and 24 of large, medium, and small sizes are concentrically set on the circular orifice plate 21. Small holes 25 are formed in a penetrating state at positions equally divided, for example, along the circumferential direction of each of the circles 22, 23, and 24. The steam from the boiler 11 is guided to the downstream side through these small holes 25. The smaller the hole diameter of the small holes 25, the more effective they are. However, if the steam passing through the small holes 25 contains moisture, there is a risk of water sealing these small holes 25, resulting in an extreme pressure increase. Water sealing occurs based on the surface tension and viscosity of water. Therefore, the minimum diameter of the small holes 25 is preferably in the range of 3.0 mm to 7.0 mm depending on the operating steam pressure, the installation location of the porous orifice 18, etc. The total number of the small holes 25 is set so that the total opening area of each small hole 25 is equal to the opening area of a single-hole orifice having the same performance as the porous orifice 18.

[0016] The porous orifice 18 can also be provided at an appropriate position in the steam supply pipe 12. For example, instead of being directly attached to the end of the valve box of the main steam valve 17 as described above, it can also be attached to the end of the inlet valve 16 of the steam header 13 on the side closer to the boiler 11, that is, the side not far from the boiler 11. However, better performance can be obtained by providing it at a position closer to the boiler 11 in the steam supply pipe 12.

[0017] Figure 3 compares the differential pressure characteristics of a single-hole orifice and a porous orifice. The horizontal axis is the steam flow rate ratio, and the vertical axis is the differential pressure. The inner diameter of the steam supply pipe 12 is 67 mm, and the hole diameter of the single-hole orifice is 29 mm. Also, the hole diameter of the porous orifice is 5.3 mm, the number of its holes is 30, and its hole arrangement is staggered along three concentric pitch circles similar to the case of Figure 2. The pitch circle diameters of the three pitch circles are 50 mm, 35 mm, and 25 mm. When measuring the differential pressure, the target flow rate of the single-hole orifice and the porous orifice is set to 100% individually, and the characteristics of the pressure loss, that is, the differential pressure, and the flow rate are compared in the range of 80 to 140.

[0018] As shown in Fig. 3, the differential pressure of the single-hole orifice is approximately 0.1 to 0.3 MPa. However, in all measured flow rate ranges, it can be understood that the pressure loss of the multi-hole orifice is about 0.1 MPa lower than that of the single-hole orifice, and the pressure loss is significantly reduced.

[0019] Fig. 4 compares the respective pressure fluctuations of two multi-hole orifices with different pore diameters. The horizontal axis is the steam flow rate ratio, and the vertical axis is the pressure fluctuation, i.e., the differential pressure. The pore diameter of the multi-hole orifice with the appropriate pore diameter is 5.3 mm, and the pore diameter of the multi-hole orifice with the undersized pore diameter is 4.5 mm. The total opening area of both orifices is 661.5 mm 2 in both cases. From the above values of the appropriate pore diameter and the undersized pore diameter, it can be understood that the minimum value of the appropriate pore diameter when comparing the pressure fluctuations shown in Fig. 4 exists within the range exceeding 4.5 mm and not exceeding 5.3 mm. This is in line with the above-mentioned matter that "the minimum diameter of the small hole 25 is preferably in the range of 3.0 mm to 7.0 mm depending on the use steam pressure, the installation location of the multi-hole orifice 18, etc."

[0020] As shown in the figure, in the case of the multi-hole orifice with the undersized pore diameter, when the flow rate ratio exceeds 100%, the pressure fluctuation slightly decreases, but when the flow rate ratio exceeds 120%, the pressure fluctuation shows a tendency to increase rapidly. This can be considered to be caused by the fact that when a small amount of moisture is contained in the steam passing through the orifice, resistance occurs when passing through the small-diameter holes and blockage (water seal) due to the amount of moisture occurs. There is also a tendency for the flow rate ratio at which the water seal pressure fluctuates depending on the size of the minimum pore diameter and the amount of moisture contained in the steam to be less than 100%.

Explanation of symbols

[0021] 11 Small boiler 12 Steam supply pipe 17 Multi-hole orifice

Claims

1. A main steam valve for controlling the steam flow rate from the boiler is connected to the steam inlet end from the boiler in the steam supply pipe that supplies steam from the boiler to the load. A porous orifice for preventing the occurrence of disturbances such as load fluctuations and pressure fluctuations in the boiler is provided at the end of the valve box of the main steam valve between the boiler and the main steam valve. A boiler device characterized by this.

2. The boiler device according to claim 1, characterized in that the minimum diameter of the orifice holes is in the range of 3.0 mm to 7.0 mm.

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