A method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit

Abstract

The present invention discloses a method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit, including: a. calculating a correction factor f1 of the atmospheric temperature on the power consumption of the forced draft fan according to the test atmospheric temperature and the designed atmospheric temperature; b. calculating a correction factor f2 of the specific air flow rate on the power consumption of the forced draft fan according to the coal quality and the measured excess air coefficient; c. calculating a correction factor f3 of the boiler input heat on the power consumption of the forced draft fan according to the measured boiler efficiency and the coal calorific value; d. calculating a correction factor f4 of the exhaust steam pressure on the power consumption of the forced draft fan according to the exhaust steam pressure of the steam turbine; f. calculating a correction factor f5 of the steam turbine aging on the power consumption of the forced draft fan according to the number of aging months of the steam turbine; g. calculating the corrected power consumption of the forced draft fan by using each correction factor and the measured power consumption; h. selecting each correction factor according to different test purposes. By using the present invention to correct the power consumption of the forced draft fan, the corrected power consumption can reflect the true performance of the equipment and the unit under the corresponding test purpose.

Description

Technical Field

[0001] The present invention belongs to the field of thermal performance tests of generator sets, and particularly relates to a method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit. Background Art

[0002] Auxiliary power consumption is an index reflecting the power consumption of the auxiliary equipment of the unit. In addition to its own performance, the factors affecting the auxiliary power consumption of the unit mainly include: (1) External conditions, such as changes in coal type and ambient temperature. When these conditions deviate from the design values, they will have a greater impact on the energy consumption of equipment such as forced draft fans, fans, and feed water pumps; (2) Operating conditions, such as when the operating mode and operating parameter settings deviate from the requirements of the design (or guaranteed) operating conditions, they will also affect the energy consumption index of the auxiliary equipment to varying degrees.

[0003] Among all the auxiliary power equipment, the factors affecting the measured power consumption of the forced draft fan are relatively complex. The main influencing factors and their influencing laws are as follows:

[0004] (1) Ambient temperature. When the ambient temperature rises, the air density will decrease. To output the same mass of air, the power consumption of the forced draft fan will increase accordingly.

[0005] (2) Forced draft fan air volume. The air volume of the forced draft fan is affected by the coal quality and the excess air coefficient of boiler combustion. The theoretical air volume of the forced draft fan can be evaluated by the specific air flow. When the specific air flow increases, the power consumption of the forced draft fan will increase accordingly.

[0006] (3) Boiler input heat. When the boiler input heat increases due to an increase in boiler efficiency or coal calorific value, the amount of coal required to output the same heat by the boiler decreases, the air volume of the forced draft fan decreases, and the power consumption of the forced draft fan will also decrease accordingly.

[0007] (4) Exhaust steam pressure of the steam turbine. When the exhaust steam pressure of the steam turbine rises with the change of environmental conditions and the output power of the unit is constant, the heat output by the boiler will increase significantly, so the amount of coal required will also increase accordingly, the air volume of the forced draft fan will increase, and the power consumption of the forced draft fan will increase accordingly.

[0008] (5) Performance aging of the steam turbine. According to objective laws, the heat consumption rate of the steam turbine gradually increases with the increase of operation time, which is called the performance aging of the steam turbine. As the operation time increases, when the output power of the unit is constant, due to the continuous performance aging of the steam turbine, the heat output by the boiler will gradually increase, so the amount of coal required will also increase due to the aging of the steam turbine, the primary air volume for transporting pulverized coal will increase, and the power consumption of the forced draft fan will increase accordingly.

[0009] Based on the above analysis, it can be seen that it is very important to correct the above influencing factors when evaluating the power consumption of the forced draft fan. However, there is no formula or calculation method in the currently published literature that fully considers correcting the above factors. Therefore, it is of great significance to explore the correction calculation method of the forced draft fan power consumption in the calculation of auxiliary power consumption in the power plant. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for correcting the power consumption of the forced draft fan in the calculation of the auxiliary power rate of a thermal power unit. In the test calculation of the auxiliary power consumption of a thermal power unit, the method provided by the present invention can correct the measured power consumption of the forced draft fan to the corresponding design conditions according to different test purposes.

[0011] To achieve the above purpose, the present invention is implemented by adopting the following technical solutions:

[0012] A method for correcting the power consumption of the forced draft fan in the calculation of the auxiliary power rate of a thermal power unit calculates the corrected power consumption of the forced draft fan using formula (1):

[0013] P FDF_corr = P FDF_m + ΔP FDF (1)

[0014] In the formula: P FDF_corr is the corrected power consumption of the forced draft fan, kW; P FDF_m is the measured power consumption of the forced draft fan, kW; ΔP FDF is the correction amount of the forced draft fan power consumption, kW;

[0015] The correction amount of the forced draft fan power consumption ΔP in formula (1) FDF is calculated using formula (2):

[0016] ΔP FDF = P FDF_m × f 1 × f 2 × f 3 × f 4 × f 5 × f 6 - P FDF_m (2)

[0017] In the formula: ΔP FDF is the correction amount of the forced draft fan power consumption, kW; P FDF_m is the measured value of the forced draft fan power consumption, kW; f 1 is the correction factor of the atmospheric temperature on the forced draft fan power consumption; f 2 is the correction factor of the fan flow rate on the forced draft fan power consumption; f 3 is the correction factor of the boiler input heat on the forced draft fan power consumption; f 4 is the correction factor of the steam turbine exhaust pressure on the forced draft fan power consumption;5 is the correction factor for the aging of steam turbine performance on the power consumption of the forced draft fan; f 6 is the correction factor for other factors affecting the power consumption of the forced draft fan;

[0018] The correction factor f for the atmospheric temperature on the power consumption of the forced draft fan in the above formula (2) 1 is calculated using formula (3):

[0019]

[0020] In the formula: T ref is the absolute boiler design atmospheric reference temperature, K; T t is the absolute test atmospheric temperature, K; t ref is the boiler design atmospheric reference temperature, °C; t t is the test atmospheric temperature, °C;

[0021] The correction factor f for the forced draft fan flow rate on the power consumption of the forced draft fan in formula (2) 2 is calculated using formula (4):

[0022]

[0023] In the formula: Sa d is the specific air flow rate at the outlet of the air preheater based on the design coal and the measured excess air coefficient, kg / kJ; Sa t is the specific air flow rate at the outlet of the air preheater based on the test coal and the measured excess air coefficient, kg / kJ; where, Sa d and Sa t are calculated with reference to the standard ASME PTC 4.

[0024] A further improvement of the present invention is that the correction factor f for the boiler input heat on the power consumption of the forced draft fan in formula (2) 3 is calculated using formula (5):

[0025]

[0026] In the formula: LHV t is the lower calorific value of the test coal, kJ / kg; LHV d is the lower calorific value of the design coal, kJ / kg; η b_t is the measured boiler efficiency, %; η b_d is the design boiler efficiency, %.

[0027] A further improvement of the present invention is that the correction factor f for the steam turbine exhaust pressure on the power consumption of the forced draft fan in formula (2) 4 is calculated using formula (6):

[0028]

[0029] Wherein: P b_t is the measured exhaust steam pressure of the steam turbine, kPa; P b_d is the designed exhaust steam pressure of the steam turbine, kPa; k is the influence coefficient of the exhaust steam pressure of the steam turbine on the heat consumption rate of the steam turbine, % / kPa.

[0030] A further improvement of the present invention lies in that the influence coefficient k of the exhaust steam pressure of the steam turbine on the heat consumption rate of the steam turbine in formula (6) is obtained from the correction curve of the back pressure to the heat consumption rate provided by the steam turbine manufacturer, or obtained by conducting a variable back pressure characteristic test of the steam turbine.

[0031] A further improvement of the present invention lies in that the correction factor f of the aging of the steam turbine performance on the power consumption of the forced draft fan in formula (2) 5 is calculated using formula (7):

[0032]

[0033] Wherein: M is the number of operating months from the first steam admission of the steam turbine to before the test, month; B is the designed output power of the steam turbine, MW; C is the rated main steam pressure, MPa.

[0034] A further improvement of the present invention lies in that the correction item f involved in formula (2) 1 is a necessary correction item, f 2 , f 3 , f 4 , f 5 are selected according to different test purposes.

[0035] A further improvement of the present invention lies in that (a) if it is a performance acceptance test after the unit is put into operation to obtain unit performance indicators comparable to the design guarantee values, f 2 ~f 5 all need to be corrected; (b) if it is a unit performance test to obtain the current actual performance indicators under the designed coal quality of the unit, f 2 , f 3 , f 4 are corrected, f 5 = 1; (c) if it is a unit performance test to obtain the actual performance indicators under the current operating coal quality of the unit, f 1 , f 4 are corrected, f 2 = 1, f 3 = 1, f 5 = 1; (d) if it is a performance test to obtain the performance indicators of the forced draft fan equipment under the design conditions, f 1 ~f 5 all need to be corrected.

[0036] A further improvement of the present invention lies in that the reference atmospheric temperature t of the boiler design in formula (3) ref is retrieved from the "Boiler Thermal Calculation Book" provided by the boiler manufacturer.

[0037] The present invention has at least the following beneficial technical effects:

[0038] In the calculation of the auxiliary power consumption test of a thermal power unit, by using the correction calculation method provided by the present method, the six factors (atmospheric temperature, air volume of the forced draft fan, measured boiler efficiency, low calorific value of coal, exhaust steam pressure of the steam turbine, and aging of the steam turbine) affecting the power consumption of the forced draft fan can be corrected to the design values according to different test purposes, so that the power consumption of the forced draft fan and the auxiliary power consumption obtained can reflect the true performance of the unit and equipment under the corresponding test purposes. Description of the Drawings

[0039] Figure 1 is a typical curve showing the relationship between the heat rate of a steam turbine and the exhaust steam pressure of the steam turbine. Detailed Embodiment

[0040] The following further details the method for correcting the power consumption of the forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of the present invention with reference to an example.

[0041] The method for correcting the power consumption of the forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit provided by the present invention includes the following steps:

[0042] The corrected power consumption of the forced draft fan is calculated using formula (1):

[0043] P FDF_corr = P FDF_m + ΔP FDF (1)

[0044] In the formula: P FDF_corr is the corrected power consumption of the forced draft fan, in kW; P FDF_m is the measured power consumption of the forced draft fan, in kW; ΔP FDF is the correction amount of the power consumption of the forced draft fan, in kW.

[0045] The correction amount ΔP of the power consumption of the forced draft fan in formula (1) FDF is calculated using formula (2):

[0046] ΔP FDF = P FDF_m × f 1 × f 2 × f 3 × f 4 × f 5 × f 6 - P FDF_m (2)

[0047] In the formula: ΔP FDF is the correction amount of the power consumption of the forced draft fan, kW; P FDF_m is the measured power consumption value of the forced draft fan, kW; f 1 is the correction factor of the atmospheric temperature on the power consumption of the forced draft fan; f 2 is the correction factor of the fan flow rate on the power consumption of the forced draft fan; f 3 is the correction factor of the boiler input heat on the power consumption of the forced draft fan; f 4 is the correction factor of the exhaust steam pressure of the steam turbine on the power consumption of the forced draft fan; f 5 is the correction factor of the steam turbine performance aging on the power consumption of the forced draft fan; f 6 is the correction factor of other factors affecting the power consumption of the forced draft fan.

[0048] The correction factor f of the atmospheric temperature on the power consumption of the forced draft fan in the above formula (2) 1 is calculated using formula (3):

[0049]

[0050] In the formula: T ref is the absolute reference temperature of the boiler design atmosphere, K; T t is the absolute test atmospheric temperature, K; t ref is the reference temperature of the boiler design atmosphere, °C; t t is the test atmospheric temperature, °C.

[0051] The reference temperature t of the boiler design atmosphere in formula (3) ref is obtained from the "Boiler Thermal Calculation Book" provided by the boiler manufacturer.

[0052] The correction factor f of the fan flow rate on the power consumption of the forced draft fan in formula (2) 2 is calculated using formula (4):

[0053]

[0054] In the formula: Sa d is the specific air flow rate at the outlet of the air preheater based on the design coal and the measured excess air coefficient, kg / kJ; Sa t is the specific air flow rate at the outlet of the air preheater based on the test coal and the measured excess air coefficient, kg / kJ. Among them, Sa d and Sa t are calculated with reference to the standard ASME PTC 4.

[0055] The correction factor f of the boiler input heat on the power consumption of the forced draft fan in formula (2) 3 is calculated using formula (5):

[0056]

[0057] In the formula: LHV t is the lower heating value of the test coal, kJ / kg; LHV d is the lower heating value of the design coal, kJ / kg; η b_t is the measured boiler efficiency, %; η b_d is the designed boiler efficiency, %.

[0058] The correction factor f for the exhaust steam pressure of the steam turbine in formula (2) on the power consumption of the forced draft fan 4 is calculated using formula (6):

[0059]

[0060] In the formula: P b_t is the measured exhaust steam pressure of the steam turbine, kPa; P b_d is the designed exhaust steam pressure of the steam turbine, kPa; k is the influence coefficient of the exhaust steam pressure of the steam turbine on the heat rate of the steam turbine, % / kPa.

[0061] The influence coefficient k of the exhaust steam pressure of the steam turbine in formula (6) on the heat rate of the steam turbine is obtained from the back pressure vs. heat rate correction curve provided by the steam turbine manufacturer as shown in the appendix, or obtained through the steam turbine variable back pressure characteristic test. Figure 1 or obtained through the steam turbine variable back pressure characteristic test.

[0062] The correction factor f for the aging of the steam turbine performance in formula (2) on the power consumption of the forced draft fan 5 is calculated using formula (7):

[0063]

[0064] In the formula: M is the number of operating months from the first steam admission of the steam turbine to before the test, months; B is the designed output power of the steam turbine, MW; C is the rated main steam pressure, MPa.

[0065] The correction item f involved in formula (2) 1 is a mandatory correction item, f 2 , f 3 , f 4 , f 5 can be appropriately selected according to different test purposes: (a) If it is a performance acceptance test after the unit is put into operation to obtain the unit performance indicators (net heat rate, net output power, coal consumption for power supply, auxiliary power of the plant, auxiliary power consumption index) that can be compared with the design guarantee values, f 2 ~f 5 all need to be corrected; (b) If it is a unit performance test to obtain the current actual performance indicators (net heat rate, net output power, coal consumption for power supply, auxiliary power of the plant, auxiliary power consumption) under the design coal quality of the unit, f2 (No correction is made to the boiler efficiency), f 3 , f 4 Make corrections, f 5 = 1; (c) If it is a unit performance test conducted to obtain the actual performance indicators (net heat rate, net output power, coal consumption for power supply, auxiliary power consumption of the plant, auxiliary power consumption rate of the plant) under the current operating coal quality of the unit, f 1 , f 4 Make corrections, f 2 = 1, f 3 = 1, f 5 = 1; (d) If it is a performance test conducted to obtain the performance indicators (auxiliary power consumption of the forced draft fan) of the forced draft fan equipment under the design conditions, f 1 ~f 5 All need to be corrected.

[0066] Other correction factors f related to the auxiliary power consumption of the forced draft fan involved in formula (2) 6 The calculation method is determined through negotiation among all parties participating in the test according to the actual operating special conditions of the unit. Whether f 6 needs to be corrected is determined through negotiation among all parties participating in the test according to the actual operating special conditions of the unit.

[0067] Example illustration:

[0068] As shown in Table 1, the example is for an overall performance acceptance test of a 660MW coal-fired thermal power unit. It is necessary to correct the auxiliary power consumption rate of the unit, so it is necessary to make corresponding corrections to the auxiliary power consumption of the forced draft fan. The example belongs to test purpose (a) in claim 10. Therefore, the correction factors f 1 ~f 5 All need to be corrected and calculated.

[0069] The test unit is equipped with 2 forced draft fans in total. Under the 100% TMCR test condition, the operating mode of the forced draft fans is that both 2 fans are running. During the test, the output power of the unit generator is 686.380MW, the total auxiliary power consumption value of the unit is 56950.7kW, and the total auxiliary power consumption of the 2 forced draft fans is 1936.2kW.

[0070] In this example, the calculation results show that by correcting the atmospheric temperature, the air volume of the forced draft fan, the measured boiler efficiency, the lower calorific value of coal, the exhaust steam pressure of the steam turbine, and the steam turbine aging to the design values, the correction amount of the auxiliary power consumption of the forced draft fan is 237.3kW, the corrected auxiliary power consumption of the forced draft fan is 2173.5kW, and the total auxiliary power of the plant after correcting the auxiliary power consumption of the forced draft fan is 57188.0kW.

[0071] Table 1 Example of correction calculation of the auxiliary power consumption of the forced draft fan

[0072]

[0073]

[0074] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made thereto based on the present invention, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit, Characterized in that, The corrected power consumption of the forced draft fan is calculated using formula (1): P FDF_corr = P FDF_m + ΔP FDF (1) Where: P FDF_corr is the corrected power consumption of the air supply fan, kW; P FDF_m is the measured power consumption of the air supply fan, kW; ΔP FDF is the correction amount of the power consumption of the air supply fan, kW; The correction amount ΔP of the blower power consumption in Formula (1) FDF is calculated using Formula (2): ΔP FDF = P FDF_m × f 1 × f 2 × f 3 × f 4 × f 5 × f 6 - P FDF_m (2) Where: ΔP FDF is the correction amount of the power consumption of the forced draft fan, kW; P FDF_m is the measured power consumption value of the forced draft fan, kW; f 1 is the correction factor of the atmospheric temperature on the power consumption of the forced draft fan; f 2 is the correction factor of the fan flow rate on the power consumption of the forced draft fan; f 3 is the correction factor of the input heat of the boiler to the power consumption of the forced draft fan; f 4 is the correction factor of the exhaust steam pressure of the steam turbine to the power consumption of the forced draft fan; f 5 is the correction factor for the aging of steam turbine performance on the power consumption of the forced draft fan; f 6 is the correction factor for other factors affecting the power consumption of the forced draft fan; The correction factor f of the atmospheric temperature in the above formula (2) for the power consumption of the forced draft fan 1 is calculated using formula (3): where: T ref is the absolute reference temperature of the boiler design atmosphere, K; T t is the absolute test atmospheric temperature, K; t ref Atmospheric reference temperature for boiler design, °C; t t is the test atmospheric temperature, °C; The correction factor f of the blower flow rate in formula (2) for the blower power consumption 2 It is calculated using formula (4): Where: Sa d is the specific air flow rate at the air preheater outlet based on the design coal and the measured excess air coefficient, kg / kJ; Sa t is the specific air flow rate at the air preheater outlet based on the test coal and the measured excess air coefficient, kg / kJ; among which, Sa d and Sa t are calculated with reference to the standard ASME PTC 4.

2. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 1, Characterized in that, The correction factor f of the boiler input heat in formula (2) for the power consumption of the forced draft fan 3 The calculation is carried out using formula (5): Where: LHV t is the lower heating value of the test coal, kJ / kg; LHV d is the lower heating value of the design coal, kJ / kg; η b_t is the measured boiler efficiency, %; η b_d For the designed boiler efficiency, %.

3. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 1, Characterized in that, The correction factor f of the exhaust steam pressure of the steam turbine in formula (2) for the power consumption of the forced draft fan 4 It is calculated using formula (6): Where: P b_t is the measured exhaust steam pressure of the steam turbine, kPa; P b_d is the designed exhaust steam pressure of the steam turbine, kPa; k is the influence coefficient of the exhaust steam pressure of the steam turbine on the heat consumption rate of the steam turbine, % / kPa.

4. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 3, Characterized in that, The influence coefficient k of the exhaust steam pressure of the steam turbine on the heat consumption rate of the steam turbine in formula (6) is obtained from the correction curve of back pressure to heat consumption rate provided by the steam turbine manufacturer or through a steam turbine variable back pressure characteristic test.

5. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 1, Characterized in that, The correction factor f for the aging of steam turbine performance in Formula (2) on the power consumption of the forced draft fan 5 It is calculated using Formula (7): In the formula: M is the number of operating months from the first steam admission of the steam turbine to before the test, in months; B is the designed output power of the steam turbine, in MW; C is the rated main steam pressure, in MPa.

6. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 1, Characterized in that, The correction item f involved in formula (2) 1 is the item that must be corrected, f 2 , f 3 , f 4 , f 5 is selected according to different test purposes.

7. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 6, Characterized in that, (a) If it is a post - commissioning performance acceptance test of the unit for obtaining unit performance indicators comparable to the design guarantee values, f 2 ~f 5 shall all be corrected; (b) If it is a unit performance test for obtaining the current actual performance indicators under the design coal quality of the unit, f 2 、f 3 、f 4 shall be corrected, f 5 = 1; (c) If it is a unit performance test for obtaining the actual performance indicators under the current operating coal quality of the unit, f 1 、f 4 shall be corrected, f 2 = 1、f 3 = 1、f 5 = 1; (d) If it is a performance test for obtaining the performance indicators of the forced draft fan equipment under the design conditions, f 1 ~f 5 shall all be corrected.

8. The method for correcting the power consumption of a forced draft fan in the calculation of the auxiliary power consumption rate of a thermal power unit of a unit according to claim 1, Characterized in that, The reference atmospheric temperature t for boiler design in formula (3) ref It is obtained from the "Boiler Thermal Calculation Book" provided by the boiler manufacturer.

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