Diagnosis method for boiler degradation, diagnosis apparatus for boiler degradation, diagnosis system for boiler degradation and recording medium that records operation program

• US 7,260,502 B2
• Filed: 06/08/2005
• Issued: 08/21/2007
• Est. Priority Date: 06/28/2004
• Status: Expired due to Fees

• Current Assignee: mitsubishi hitachi power systems, ltd. (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Hayashi, Yoshiharu
• Primary Examiner(s): Hoff; Marc S.
• Assistant Examiner(s): SUAREZ, FELIX E
• Application Number:
  US11/147,438
• Publication Number:
  US 20050284346A1
• Time in Patent Office: 804 Days
• Field of Search: 702/22, 702/24, 702/84, 702181-183, 702/185, 702/186, 702/188, 415/118, 422/198, 429/20
• US Class Current: 702/183
• CPC Class Codes: F22B 35/18 Applications of computers to steam boiler control
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

One of the thermal transmission rates that represent thermal transmission from gas to steam in a heat exchanger constituting a boiler is calculated based on thermal conductivity rate of pipes and thermal transfer of steam and gas, and the other is compared with the thermal conductivity rate calculated based on the thermal conductivity rate of the pipes and thermal transfer rate of steam and gas.

Claims

1. A diagnosis method of degradation of a boiler, comprising:

calculating a first thermal transmission rate from a difference in thermal quantity of gas or steam between an entrance and exit of a heat exchanger with respect to at least one of heat exchangers constituting the boiler;

calculating a second thermal transmission rate based upon a thermal conductivity rate of pipes and thermal conductivity transfer rate of steam and gas of the heat exchanger;

comparing the first and second thermal transmission rates; and

carrying out diagnosis of the progress of degradation, wherein the diagnosis is displayed on a display device.

2. The method of degradation diagnosis of a boiler according to claim 1, which further comprises displaying a degradation tendency of the respective thermal transmission rates calculated in the above procedure.

3. The method of degradation diagnosis of a boiler according to claim 2, wherein the displaying is conducted with respect to plural heat exchangers constituting the boiler.

4. The method of degradation diagnosis of a boiler according to claim 1,

wherein when the first and second thermal transmission rates are calculated based upon thermal conductivity of the pipes and thermal transfer of the gas and steam, the second thermal transmission rates are calculated by the equations 6a and 6b, under the conditions that the thermal transmission is K, an inner diameter of pipes D₁, an outer diameter of the pipes is D₂, thermal transfer rates of the steam and gas are h_w and h_g, the thermal conductivity of the pipes is λ

m, fin efficiency is φ

, an area of the fin is A_f, and an area of the bottom of the fin is A_b, and

when the first and second thermal transmission rates is calculated, the first thermal transmission rates are calculated by the equations (4a) and (4b) under the conditions that thermal quantity is Q, flow rates of steam and gas are F_w and F_g respectively, entrance enthalpies of steam and gas are H_w,in and H_{g, in}, exit enthalpies of H_w, and H_g respectively, a thermal transfer area is A, and a logarithmic average temperature difference between the steam and gas is Δ

T, and

wherein comparing the first and second thermal transmission rates is conducted by the thermal transmission rates from the gas to steam in the heat exchanger calculated by the equations (6a), (6b), (4a), and (4b).

$\begin{array}{cc}\begin{array}{c}Q=F_w·<br><br>\left(H_{w,<br><br>\mathrm{out}}-H_{w,<br><br>\mathrm{in}}\right)=F_g·<br><br>\left(H_{g,<br><br>\mathrm{in}}-H_{g,<br><br>\mathrm{out}}\right)\hspace{1em}<br><br>\\ Q=K·<br><br>A.·<br><br>T<br><br><br><br>\hspace{1em}<br><br>\hspace{1em}<br><br>\hspace{1em}<br><br>\end{array}& \begin{array}{c}\left(4<br><br>a\right)\\ \left(4<br><br>b\right)\end{array}\\ \begin{array}{c}\frac{1}{K}=<br><br>\frac{D_2}{D_1}·<br><br>\frac{1}{h_w}+\frac{D_{2<br><br>}<br><br>\mathrm{In}<br><br><br><br>\left(D_2/D_1\right)}{2}·<br><br>\frac{1}{{}_m}+\\ <br><br>\frac{1}{h_g<br><br>\left(A_f.+A_b\right)/\left(A_f+A_b\right)}\end{array}& \left(6<br><br>a\right)\\ A_f+A_b=A.& \left(6<br><br>b\right)\end{array}$

5. A boiler degradation diagnosis system comprising:

a measuring device for steam and gas taken from a boiler;

a database for storing design information of heat exchangers constituting the boiler and physical property values of steam and gas,

a calculation device for calculating a first thermal transmission rates based on thermal difference of gas or steam at an exit and entrance of heat exchangers of pipes and for calculating a second thermal transmission rates based upon thermal conductivity rate of pipes, and thermal transfer rates of steam and gas, stored in the database; and

a display device for displaying a change of tendency in the first and second thermal transmission rates with respect to the same heat exchanger.

6. The boiler degradation diagnosis system according to claim 5, wherein the calculation device compares the first and second thermal transmission rates calculated in the above step, thereby to diagnose the progress of degradation.

7. The boiler degradation diagnosis system according to claim 5, wherein the display device for displaying a degradation tendency of the respective thermal transmission rates is calculated by the calculation device.

8. The boiler degradation diagnosis system according to claim 5, wherein,

when the first and second thermal transmission rates are calculated based upon the thermal transfer rates of steam and gas or the thermal conductivity of the pipes, the calculation device refers to design database storing the boiler design data under the conditions that the thermal transmission rate is K, an inner diameter and outer diameter of the pipes are D₁ and D₂, respectively, thermal transfer rates of steam and gas are h_w and h_g respectively, a thermal conductivity of the pipes is λ

m, a fin efficiency is φ

, an area of the fin is A_f and the bottom area of the fin is A_b, to calculate by the equations (6a) and (6b), when the first and second thermal transmission rates is calculated, the first thermal transmission rates are is calculated by the equations (4a) and (4b) under the conditions that thermal quantity is Q, flow rates of steam and gas are F_w and F_g respectively, entrance enthalpies of steam and gas are H_w,in and H_{g, in}, exit enthalpies of H_w, and H_g respectively, a transfer area is A, and a logarithmic average temperature difference between the steam and gas is Δ

T.

$\begin{array}{cc}Q=F_w·<br><br>\left(H_{w,<br><br>\mathrm{out}}-H_{w,<br><br>\mathrm{in}}\right)=F_g·<br><br>\left(H_{g,<br><br>\mathrm{in}}-H_{g,<br><br>\mathrm{out}}\right)& \left(4<br><br>a\right)\\ Q=K·<br><br>A.·<br><br>T<br><br>& \left(4<br><br>b\right)\\ \begin{array}{c}\frac{1}{K}=<br><br>\frac{D_2}{D_1}·<br><br>\frac{1}{h_w}+\frac{D_{2<br><br>}<br><br>\mathrm{In}<br><br><br><br>\left(D_2/D_1\right)}{2}·<br><br>\frac{1}{{}_m}+\\ <br><br>\frac{1}{h_g<br><br>\left(A_f.+A_b\right)/\left(A_f+A_b\right)}\end{array}& \left(6<br><br>a\right)\\ A_f+A_b=A.& \left(6<br><br>b\right)\end{array}$

9. A recording medium for a boiler degradation diagnosis program for causing a computer to calculate a first thermal transmission rates from thermal quantity difference in steam or gas between an exit and entrance of at least one of heat exchangers, further to calculate a second thermal transmission rates based upon thermal conductivity of pipes and thermal transfer rates of steam and gas with respect to the same heat exchanger, to compare the first and second thermal transmission rates, diagnose progress of degradation, and to display a diagnosis result.

10. The recording medium according to claim 9, wherein the medium causes the computer to display a tendency of change of the respective thermal transmission rates.

11. The recording medium according to claim 10, wherein the medium causes the computer to display a tendency of change of the respective thermal transmission rates of the plural heat exchangers.

12. The recording medium according to claim 9, wherein

the medium causes the computer to calculate the first and second thermal transmission rates based upon thermal conductivity of the pipes and thermal transfer of the gas and steam, the second thermal transmission rates are calculated by the equations 6a and 6b, under the conditions that the thermal transmission is K, an inner diameter of pipes id D₁, an outer diameter of the pipes is D₂, thermal transfer rates of the steam and gas are h_w and h_g, the thermal conductivity of the pipes is λ

m, fin efficiency is φ

, an area of the fin is A_f, and an area of the bottom of the fin is A_b, or

the medium causes the computer to calculate the first and second thermal transmission rates, the first thermal transmission rates are calculated by the equations 4a and 4b under the conditions that thermal quantity is Q, flow rates of steam and gas are F_w and F_g respectively, entrance enthalpies of steam and gas are H_w,in and H_{g, in}, exit enthalpies of H_w, and H_g respectively, a thermal transfer area is A, and a logarithmic average temperature difference between the steam and gas is Δ

T, and

wherein the medium causes the computer to compare the first and second thermal transmission rates by the thermal transmission rates from the gas to steam in the heat exchanger calculated by the equations (6a), (6b), (4a), and (4b).

$\begin{array}{cc}Q=F_w·<br><br>\left(H_{w,<br><br>\mathrm{out}}-H_{w,<br><br>\mathrm{in}}\right)=F_g·<br><br>\left(H_{g,<br><br>\mathrm{in}}-H_{g,<br><br>\mathrm{out}}\right)& \left(4<br><br>a\right)\\ Q=K·<br><br>A.·<br><br>T<br><br>& \left(4<br><br>b\right)\\ \begin{array}{c}\frac{1}{K}=<br><br>\frac{D_2}{D_1}·<br><br>\frac{1}{h_w}+\frac{D_{2<br><br>}<br><br>\mathrm{In}<br><br><br><br>\left(D_2/D_1\right)}{2}·<br><br>\frac{1}{{}_m}+\\ <br><br>\frac{1}{h_g<br><br>\left(A_f.+A_b\right)/\left(A_f+A_b\right)}\end{array}& \left(6<br><br>a\right)\\ A_f+A_b=A.& \left(6<br><br>b\right)\end{array}$