Method for analyzing pipe wall temperature of heat transfer pipe in boiler furnace

Abstract

To provide a method for analyzing a pipe wall temperature of a heat transfer pipe in a boiler furnace, which can simply grasp a pipe wall temperature of a heat transfer pipe at any position in the heat transfer pipe inside a boiler instantly or at any time, and also can simply grasp pipe wall temperatures of heat transfer pipes of a superheater and a reheater other than a representative boiler.SOLUTION: A method for analyzing a pipe wall temperature of a heat transfer pipe in a boiler furnace using a heat load factor of the heat transfer pipe of the boiler, calculates a pipe wall temperature of a heat transfer pipe from a local heat load at any position of the heat transfer pipe, which is calculated from an average heat load and the heat load factor, based on steam conditions on an inlet side and an outlet side of the heat transfer pipe that are not exposed to combustion gas, and the average heat load and heat load factor derived from heat transfer pipe specifications.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace. [Background technology]

[0002] The boiler has multiple superheaters and reheaters in the boiler furnace. The superheaters and reheaters have multiple heat transfer tubes arranged in parallel. These multiple heat transfer tubes are exposed to high temperatures due to convection heat from the combustion gas and radiant heat from the furnace, so the temperature of the tube walls becomes higher than the internal fluid temperature.

[0003] In the boiler furnace, the combustion gas reaches 1000°C or higher. Among them, methods for grasping the tube wall temperature of the heat transfer tube include CFD (Computational Fluid Dynamics) analysis and a method of measuring the temperature by embedding a thermocouple in the heat transfer tube. However, the CFD analysis performed each time is costly and time-consuming, and the temperature measurement of the heat transfer tube is directly exposed to high-temperature gas, so it is not possible to perform stable long-term measurement, and grasping the tube wall temperature of the heat transfer tube is not easy (for example, see Non-Patent Document 1). On the other hand, since the heat transfer tube of the boiler is in a high-temperature and high-pressure environment, there is a concern that it may be damaged by creep (hereinafter referred to as "creep damage"). In order to prevent the creep damage, creep life evaluation is necessary. In addition, a method for calculating the tube wall temperature of the heat transfer tube with an accuracy suitable for creep life evaluation is also required. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Yoshihiko Endo, Shigehiro Miyamae, Yasunori Ando, ​​"3D Simulation of Flow, Heat Transfer and Combustion in a Boiler Furnace", Ishikawajima-Harima Technical Report, Vol. 34, No. 2, March 1994 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional methods require CFD analysis or temperature measurement each time, which means that the problem can only be solved by time-consuming and costly methods. In addition, conventional CFD analysis has the problem that it is practically difficult to calculate the temperature at any position on the heat transfer tube instantly or at any time, and that it is difficult to perform stable long-term temperature measurement because the heat transfer tube is directly exposed to high-temperature gas. Note that the temperature also changes depending on the change in operating conditions over time, but the term "any time" refers to the change in operating conditions.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, which can easily grasp the wall temperature of the heat transfer tube at any position and any time of the heat transfer tube by using a heat load factor obtained based on CFD analysis and actual measurement of the wall temperature of the heat transfer tube.Furthermore, the present invention aims to provide a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, which can easily grasp the wall temperature of the heat transfer tube of the superheater or reheater of the representative boiler by making the heat load factor of the superheater or reheater of the representative boiler into master data and applying the master data of the heat load factor to boilers other than the representative boiler having a superheater or reheater similar to the representative boiler. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A method for analyzing the wall temperature of a heat transfer tube in a boiler furnace using a thermal load factor of the boiler heat transfer tube, comprising: A method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, comprising the steps of: calculating a wall temperature of the heat transfer tube from a local heat load at any position of the heat transfer tube, the local heat load being determined from the average heat load and the heat load factor, based on steam conditions at the inlet and outlet sides of the heat transfer tube that are not exposed to combustion gas, and an average heat load and a heat load factor derived from the heat transfer tube specifications; [2] A method for calculating the thermal load factor of a boiler heat transfer tube and analyzing the wall temperature of the heat transfer tube in a boiler furnace, comprising: The boilers are classified into a representative boiler and boilers other than the representative boiler, The representative boiler has at least a superheater A, and the boilers other than the representative boiler have at least a superheater B similar to the representative boiler, A first step of calculating a thermal load factor A of the representative boiler by CFD analysis or measuring a wall temperature of a heat transfer tube in a boiler furnace, and acquiring master data of a thermal load factor distribution A of at least a superheater A in the representative boiler; A second step of setting a thermal load magnification distribution B of a heat transfer tube of a boiler other than the representative boiler based on the similarity of the superheater B with respect to the representative boiler; a third step of correcting the heat load magnification distribution B in the second step; and a fourth step of calculating a wall temperature of the heat transfer tube from the heat load magnification distribution B obtained in the first to third steps. [3] The representative boiler has at least a superheater A and a reheater A, and the boilers other than the representative boiler have a superheater B and a reheater B similar to those of the representative boiler, The first step is a step of calculating a heat load factor A of the representative boiler by CFD analysis or measuring the wall temperature of a heat transfer tube in a boiler furnace, and acquiring master data of a heat load factor distribution A of a superheater A and a reheater A in the representative boiler; The second step is a step of setting a thermal load multiplier distribution B of heat transfer tubes other than the representative boiler based on the similarity of the superheater B and the reheater B with respect to the representative boiler, in a boiler other than the representative boiler. Effect of the Invention

[0008] According to the present invention, a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace can be provided, which can grasp the wall temperature of the heat transfer tube in a simpler manner by using a thermal load factor. In addition, a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace can be provided, which can grasp the wall temperature of a heat transfer tube in a superheater or reheater installed in a boiler furnace other than the representative boiler in a simpler manner by using a thermal load factor in the superheater or reheater obtained based on a CFD analysis or a measurement of the wall temperature of the heat transfer tube in the representative boiler. As a result, for example, the wall temperature of the heat transfer tube can be instantly calculated using the operating data of the boiler, and the creep life evaluation of the heat transfer tube can be performed instantaneously and appropriately reflecting the change in the wall temperature of the heat transfer tube. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of a boiler to which a method for analyzing a tube wall temperature of a heat transfer tube in a boiler furnace according to an embodiment of the present invention is applied. [Diagram 2] 1 is a schematic diagram showing a group of heat transfer tubes constituting a superheater or a reheater provided in a boiler to which a method for analyzing the tube wall temperature of a heat transfer tube in a boiler furnace according to the present embodiment is applied. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail.

[0011] (First embodiment) [Method of analyzing the wall temperature of boiler heat transfer tubes using thermal load factor] A method for analyzing the wall temperature of a heat transfer tube in a boiler furnace according to one embodiment of the present invention is a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace using a thermal load factor of the heat transfer tube of the boiler, the method calculating the wall temperature of the heat transfer tube from a local thermal load at an arbitrary position of the heat transfer tube, which is obtained from the average thermal load and the thermal load factor, based on steam conditions on the inlet and outlet sides of the heat transfer tube that are not exposed to combustion gas, and an average thermal load and a thermal load factor derived from the heat transfer tube specifications.

[0012] FIG. 1 is a schematic diagram showing an example of a boiler to which the method of analyzing the wall temperature of a heat transfer tube in a boiler furnace according to the present embodiment is applied.

[0013] A method for calculating the wall temperature of the heat transfer tube from the heat load factor will be described. The tube wall temperature of the heat transfer tube is calculated by calculating the local heat load from the average heat load and the heat load magnification, and then calculating the tube wall temperature from the local heat load using steady-state heat conduction calculations. The local heat load is calculated based on the following formulas (1) and (2). In the following formulas (1) and (2), Qa is the average heat load (kW / m), E0 is the steam enthalpy (kJ / kg) at the outlet of the heat transfer tube, Ei is the steam enthalpy (kJ / kg) at the inlet of the heat transfer tube, Fs is the flow rate of steam flowing through the heat transfer tube (kg / s), L is the length of the heat transfer tube (m), Qm is the local heat load (kW / m), and Mq is the heat load factor (-).The heat load factor is the ratio of the local maximum heat absorption amount to the average heat absorption amount in the boiler furnace, and is an index that indicates the distribution state of the heat absorption amount.

[0014] Calculate the average thermal load (Qa) based on the following formula (1). Qa = ((E0-Ei) × Fs) / L (1)

[0015] Calculate the local heat load (Qm) based on the following equation (2). Qm = Mq × Qa (2)

[0016] The wall temperature of the heat transfer tube is calculated using the obtained local heat load (Qm) by steady-state heat conduction calculation.

[0017] According to the method for analyzing the wall temperature of a heat transfer tube in a boiler furnace of this embodiment, it is possible to provide a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, which is capable of determining the heat transfer tube temperature at any position and any time on the heat transfer tube by using a thermal load magnification.

[0018] Second embodiment [Calculation of heat load factor and method of analyzing tube wall temperature in boiler furnace using heat load factor] A method for analyzing the tube wall temperature of a heat transfer tube in a boiler furnace according to one embodiment of the present invention is a method for determining a thermal load factor of a heat transfer tube of a boiler and analyzing the tube wall temperature of a heat transfer tube in a boiler furnace, the boiler being classified into a representative boiler and boilers other than the representative boiler, the representative boiler having at least a superheater A, and the boilers other than the representative boiler having at least a superheater B similar to the representative boiler, and the thermal load factor of the representative boiler is determined by CFD analysis or measurement of the tube wall temperature of a heat transfer tube in a boiler furnace. a first step of calculating a heat load multiplier distribution A of at least the representative boiler and acquiring master data of a heat load multiplier distribution A of a superheater A in the representative boiler; a second step of acquiring, in a boiler other than the representative boiler, a heat load multiplier distribution B of a heat transfer tube other than the representative boiler from a similarity of the superheater B with the representative boiler; a third step of correcting the heat load multiplier distribution B in the second step; and a fourth step of calculating a tube wall temperature of the heat transfer tube from the heat load multiplier distribution B obtained in the first to third steps.

[0019] The method for analyzing the tube wall temperature of a heat transfer tube in a boiler furnace according to the present embodiment is also applied to a boiler as shown in Fig. 1. Fig. 2 is a schematic diagram showing heat transfer tubes constituting a superheater or a reheater provided in a boiler to which the method for analyzing the tube wall temperature of a heat transfer tube in a boiler furnace according to the present embodiment is applied. As shown in FIG. 1, the boiler 1 has a combustion chamber (boiler furnace) 2, a burner 3, a primary superheater 4, a secondary superheater 5, a tertiary superheater 6, and a reheater .

[0020] The burner 3 is provided at the bottom of the combustion chamber 2 so that the flame outlet is inside the combustion chamber 2. The secondary superheater 5 is provided in the upper part of the combustion chamber 2 at a position where it receives more radiation from the flame or combustion gas from the burner 3 inside the combustion chamber 2 . The tertiary superheater 6 is provided in the upper part of the combustion chamber 2 at a position downstream of the secondary superheater 5 in the flow direction of the combustion gas.

[0021] As shown in FIG. 2, the superheaters (primary superheater 4, secondary superheater 5, tertiary superheater 6) or the reheater 7 have a plurality of heat transfer tubes 10 arranged in parallel.

[0022] Among the multiple boilers, a typical boiler having superheaters (primary superheater 4, secondary superheater 5, tertiary superheater 6) and a reheater 7 as shown in FIG. 1 is taken as a representative boiler.

[0023] "First step" In the first step, master data of the heat load magnification distribution A in at least the superheater A of the representative boiler is obtained. That is, in the first step, when at least the representative boiler has only the superheater A, master data of the heat load magnification distribution A in the superheater A is obtained.

[0024] A method for obtaining master data of the thermal load magnification distribution will be described. Since the heat load multiplier distribution differs depending on the placement of the superheater and reheater in the boiler facility, all superheaters and reheaters placed in positions requiring temperature analysis of the heat transfer tubes are selected as the target superheaters and reheaters for which the heat load multiplier distribution is to be calculated. Since the heat load multiplier distribution is calculated from the heat load distribution of multiple representative points, representative points necessary for calculating the heat load multiplier distribution are selected for each of the selected superheaters and reheaters. Note that the analysis accuracy of this method can be improved by appropriately selecting the representative points and increasing the number of representative points.

[0025] The tube wall temperature at the selected representative points is determined by CFD analysis or by measuring the tube wall temperature of the heat transfer tube in the boiler furnace. Next, a steady-state heat conduction calculation is used to determine the local heat load (Qm) that matches the tube wall temperature at a representative point of the heat transfer tube, which is determined by CFD analysis or by measuring the tube wall temperature of the heat transfer tube in the boiler furnace. Next, for the selected superheater and reheater, the average thermal load (Qa) is calculated based on the steam conditions at the inlet and outlet sides of the superheater and reheater, which are constantly being measured, and the heat transfer tube specifications of the superheater and reheater, using the above formula (1). Next, the heat load magnification is calculated by dividing the local heat load (Qm) by the average heat load (Qa) based on the transformation of the above formula (2). The thermal load magnifications of all the representative points selected in the same manner are calculated.

[0026] At least, linear interpolation is performed from the heat load factor of the representative point of superheater A to determine the heat load factor of an arbitrary position and obtain the heat load factor distribution A. This is used as the master data of the heat load factor distribution A of the representative boiler.

[0027] In the first step, when the representative boiler has at least a superheater A and a reheater A, master data of the heat load magnification distribution A in the superheater A and the reheater A of the representative boiler may be acquired. The method of acquiring the master data of the heat load magnification distribution A is as described above.

[0028] "Second step" In the second step, a thermal load magnification distribution B of a superheater B is set in a boiler other than the representative boiler that is different from the representative boiler based on the master data. That is, in the second step, when a boiler other than the representative boiler has only a superheater B, master data of a thermal load magnification distribution B in the superheater B is set. A superheater A of a representative boiler that is similar to superheater B of a boiler other than the representative boiler is selected. Here, similarity refers to the arrangement of the superheater in the boiler facility and the configuration of the heat transfer tube group. By making the relative position of an arbitrary position of the heat transfer tube group of superheater B of the other than the representative boiler correspond to the relative position of the heat transfer tube group of superheater A of the selected representative boiler, the heat load multiplier distribution A of superheater A of the selected representative boiler is set as the heat load multiplier distribution B of superheater B of the other than the representative boiler.

[0029] In the second step, when the representative boiler has at least a superheater A and a reheater A, and a boiler other than the representative boiler has a superheater B and a reheater B similar to those of the representative boiler, the superheater A and the reheater A of the representative boiler that are similar to the superheater B and the reheater B of the boiler other than the representative boiler are selected. Here, similarity refers to the arrangement of the superheaters and the reheaters in the boiler facility and the heat transfer tube group configuration. By making the relative positions of any positions of the heat transfer tube groups of the superheater B and the reheater B of the boiler other than the representative boiler correspond to the relative positions of the heat transfer tube groups of the superheater A and the reheater A of the selected representative boiler, the heat load magnification distribution A of the superheater A and the reheater A of the selected representative boiler is set as the heat load magnification distribution B of the superheater B and the reheater B of the boiler other than the representative boiler.

[0030] "The third step" In the third step, the heat load magnification distribution B obtained in the second step is corrected to reflect the results of CFD analysis for positions where the tube pitch changes locally in the heat transfer tube bank, and is corrected to a heat load magnification that makes the measured value of the steam oxide scale thickness formed on the heat transfer tube consistent with the calculated steam oxide scale thickness.

[0031] "The fourth step" In the fourth step, the tube wall temperature of the heat transfer tube is calculated from the heat load magnification distribution B obtained in the steps up to the third step according to the contents described in the first embodiment.

[0032] According to the method for analyzing the wall temperature of a heat transfer tube in a boiler furnace of this embodiment, by using the thermal load factor A in the superheater A and the reheater A obtained based on CFD analysis and measurement of the wall temperature of the heat transfer tube in the representative boiler, it is possible to provide a method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, which can grasp the wall temperatures of the heat transfer tubes in the superheater B and the reheater B installed in a furnace other than the representative boiler in a simpler manner. [Explanation of symbols]

[0033] 1. Boiler 2 Combustion chamber (boiler furnace) 3 Burner 4 Primary superheater 5. Secondary superheater 6. Tertiary superheater 7 Reheater 10 heat pipes

Claims

1. A method for analyzing a tube wall temperature of a heat transfer tube in a boiler furnace using a thermal load factor of the heat transfer tube of the boiler, comprising: A method for analyzing the wall temperature of a heat transfer tube in a boiler furnace, comprising the steps of: calculating a wall temperature of the heat transfer tube from a local heat load at any position of the heat transfer tube, the local heat load being determined from the average heat load and the heat load factor, based on steam conditions at the inlet and outlet sides of the heat transfer tube that are not exposed to combustion gas, and an average heat load and a heat load factor derived from the heat transfer tube specifications;

2. A method for calculating a thermal load factor of a heat transfer tube of a boiler and analyzing a tube wall temperature of the heat transfer tube in a boiler furnace, comprising: The boilers are classified into a representative boiler and boilers other than the representative boiler, The representative boiler has at least a superheater A, and the boilers other than the representative boiler have at least a superheater B similar to the representative boiler, A first step of calculating a thermal load factor A of the representative boiler by CFD analysis or measuring a wall temperature of a heat transfer tube in a boiler furnace, and acquiring master data of a thermal load factor distribution A of at least a superheater A in the representative boiler; A second step of setting a thermal load magnification distribution B of the heat transfer tubes of the boiler other than the representative boiler based on the similarity of the superheater B between the representative boiler and the boiler other than the representative boiler; a third step of correcting the thermal load magnification distribution B in the second step; and a fourth step of calculating a wall temperature of the heat transfer tube from the heat load magnification distribution B obtained in the third step and the fourth step.

3. The representative boiler has at least a superheater A and a reheater A, and the boilers other than the representative boiler have a superheater B and a reheater B similar to those of the representative boiler, The first step is a step of calculating a heat load factor A of the representative boiler by CFD analysis or measuring a wall temperature of a heat transfer tube in a boiler furnace, and acquiring master data of a heat load factor distribution A of a superheater A and a reheater A in the representative boiler; 3. The method for analyzing the wall temperature of a heat transfer tube in a boiler furnace according to claim 2, wherein the second step is a step of setting a thermal load magnification distribution B of a heat transfer tube of a boiler other than the representative boiler based on similarity of the superheater B and the reheater B with respect to the representative boiler.

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