CN113158443A - Correction calculation method for influence of high-temperature economizer operation on steam turbine heat consumption - Google Patents

Abstract

The invention discloses a method for correcting and calculating the influence of the operation of a high-temperature economizer on the heat consumption of a steam turbine.

Description

Correction calculation method for influence of high-temperature economizer operation on steam turbine heat consumption

Technical Field

The invention relates to a method for correcting heat consumption of a steam turbine, in particular to a method for correcting and calculating the influence of high-temperature economizer operation on the heat consumption of the steam turbine.

Background

When a thermal performance test of the steam turbine is carried out, main parameters such as main steam pressure, temperature, exhaust steam pressure and the like are within a certain deviation range from a design value and are kept stable. In the test data processing process, in order to evaluate the thermal performance of the unit, the heat consumption under the parameters needs to be corrected so as to evaluate the heat consumption level of the unit under the rated working condition.

At present, parameters are mainly corrected by using a correction curve provided by a manufacturing plant, and the parameters are mainly parameter correction and mainly relate to main steam pressure, main steam temperature, reheat steam pressure, reheat steam temperature and exhaust steam pressure. The correction curve is suitable for a thermodynamic system provided by an equipment manufacturer.

In fact, most units are modified and optimized to the initial thermodynamic system under the pressure of unit energy saving and consumption reduction so as to reduce the heat consumption of the units as much as possible. Therefore, the steam turbine test result is corrected only by using the correction curve provided by the equipment manufacturer, the running condition of the unit cannot be comprehensively reflected, particularly, when a large system modification is involved, the thermal performance of the unit is greatly influenced, and the modification needs to be independently corrected and calculated.

In the aspect of waste heat recovery, a high-temperature economizer is additionally arranged on part of the units, and part of the unit supplies water by recovering the amount of flue gas in front of or in parallel with an air preheater of the boiler. When the unit has been retrofitted, it is necessary to evaluate the economics of its production. The field evaluation is generally carried out in a test mode, and the obtained data is calculated and corrected and then compared with a design value. There is currently no corresponding correction calculation method.

For a conventional water supply system, water supply sequentially passes through a No. 3 high pressure heater, a No. 2 high pressure heater and a No. 1 high pressure heater, exchanges heat with corresponding steam extracted by a steam turbine, and then enters a boiler economizer system, as shown in FIG. 1. In order to recover the heat of the flue gas, part of the units transform the system. After transformation, part of the feed water flow sequentially passes through a No. 3 high pressure heater, a No. 2 high pressure heater and a No. 1 high pressure heater according to the previous flow direction, and the other part of the feed water flows to the high temperature economizer and then is converged into a No. 1 high pressure heater outlet. Because the water supply amount through No. 3, No. 2 and No. 1 high pressure heating is reduced, under the condition that the temperature of No. 1 high pressure heating outlet is not changed, the steam extraction amount of the 1 section, the 2 section and the 3 section is reduced, the work amount in the high pressure cylinder and the medium pressure cylinder is increased, and the heat consumption of the unit is further influenced.

Disclosure of Invention

The invention provides a numerical calculation and correction method aiming at a unit additionally provided with a high-temperature economizer system so as to reflect the influence of the operation of the high-temperature economizer system on the thermal performance of the unit.

The technical scheme adopted by the invention for solving the problems is as follows: a correction calculation method for influence of high-temperature economizer operation on steam turbine heat consumption is characterized by comprising the following steps:

when the high-temperature economizer system is not in operation, the flow rate is Q_IntoTemperature t_IntoThe feed water is heated by a main feed water circuit such as No. 3 high-pressure heater, No. 2 high-pressure heater, No. 1 high-pressure heater and the like in sequence and then enters the economizer, and the temperature of the outlet of each heater is t₃、t₂、t₁… … are provided. After the heat and mass balance calculation is carried out on the corresponding heater, the corresponding steam extraction quantity of the steam turbine is Q₃、Q₂、Q₁… … are provided. The above parameters are selected from the thermal equilibrium map provided by the equipment manufacturer.

After the high-temperature economizer system is put into operation, the water supply flow entering the water supply main circuit and the high-temperature economizer is adjusted through the opening degree of the high-temperature economizer inlet adjusting valve. That is, the flow rate into the main water supply line is Q'_IntoThe outlet temperature and the extraction steam quantity of each heater are changed due to the change of the flow, and the corresponding heater parameters are t'₃、t′₂、t′₁… … with respective extraction flows of Q'₃、Q′₂、Q′₁… … are provided. Flow through the high temperature economizer is Q_{Gao Sheng}The outlet temperature of the high-temperature economizer is t_{Gao Sheng}. The above parameters are derived from the operating data obtained during the test.

Under the condition that the input heat of the unit is not changed, after the high-temperature economizer is put into operation, the water supply flow through the main path is reduced, so that the steam extraction flow of the corresponding heater is reduced, the work capacity in the cylinder is increased, and the heat consumption of the unit is further reduced.

For a conventional coal-fired unit, 1 extraction and 2 extractions are steam extraction on a high-pressure cylinder of a steam turbine, and 3 extractions are steam extraction on a medium-pressure cylinder of the steam turbine. 1, reducing the extracted steam quantity, increasing the work quantity in the cylinder, including the corresponding work quantities of a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder, and increasing the heat absorption quantity of the cylinder in a reheater; 2, when the extracted steam quantity is reduced, increasing the heat absorption quantity of a reheater and increasing the work quantity of a medium pressure cylinder and a low pressure cylinder; 3, the extracted steam quantity is reduced, and the increased work quantity is 3 work quantities of extraction to the middle discharge flow passage part and the low-pressure cylinder.

Then, the medium-temperature economizer is put into operation, on one hand, the work load of the unit is increased, and on the other hand, the heat input is increased. The method comprises the following specific steps:

the work amount increased by reducing the steam extraction in the section 1 is as follows:

W₁＝(Q₁-Q’₁)*((h₁-h_gp)+(h_zr-h_zp)+(h_dj-h_pq)) (1)

the 1-stage extraction reduces the heat absorption increased in the reheater as follows:

H_z1＝(Q₁-Q′₁)*(h_zc-h_zr) (2)

the work amount increased by reducing the steam extraction in the 2-section is as follows:

W₂＝(Q₂-Q′₂)*((h_zr-h_zp)+(h_dj-h_pq)) (3)

the 2-stage extraction reduces the heat absorption increased in the reheater by:

H_z2＝(Q₂-Q′₂)*(h_zc-h_zr) (4)

the work amount increased by reducing the steam extraction in the 3 sections is as follows:

W₃＝(Q₃-Q′₃)*((h₃-h_zp)+(h_dj-h_pq)) (5)

then, the input heat of the turboset is H, and the generating capacity of the unit without using the high-temperature economizer is W_{Is provided with}The design heat consumption of the steam turbine is as follows:

q_{is provided with}＝H/W_{Is provided with} (6)

The generating capacity of the high-temperature economizer used by the unit is as follows:

W_throw-in＝W_{Is provided with}+W₁+W₂+W₃ (7)

The heat consumption of the steam turbine is as follows:

q_throw-in＝(H+H_z1+H_z2)/W_Throw-in (8)

The rate of change of heat rate is:

in the formula: q₁、Q’₁、Q₂、Q’₂、Q₃、Q’₃The first pumping flow, the second pumping flow and the third pumping flow h before and after the high-temperature economizer is put into use₁、h_zr、h_zp、h_dj、h_pq、h₃Respectively is a first enthalpy extraction value, a reheating steam enthalpy value, a middle exhaust enthalpy value, a low-pressure cylinder steam inlet enthalpy value, a low-pressure cylinder steam exhaust enthalpy value and a three enthalpy extraction value.

h_zc、h_zrThe enthalpy values of the outlet and the inlet of the reheater.

According to the calculation method, under the rated load of the unit, a plurality of main water supply path flow values are given in the water supply flow change range, corresponding heat consumption change rate values are obtained respectively, and corresponding curves are obtained in a numerical fitting mode and used for correction calculation.

Compared with the prior art, the invention has the following advantages and effects: the current correction method or curve of the high-temperature economizer without needle can not quantify the influence of the operation of the high-temperature economizer on the thermal performance of the unit. The method provided by the invention combines parameters provided by equipment manufacturers, corrects the steam turbine test result by adopting a data calculation method, can accurately reflect the influence of the operation of the high-temperature economizer system on the thermal performance of the unit and the thermal performance condition of the steam turbine, and can more comprehensively reflect the operation condition of the unit.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a water supply system with a high-temperature economizer system, which is typical in the related art.

Fig. 2 is a schematic structural view of a typical feedwater system with a high-temperature economizer system according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.

Examples are given.

Referring to fig. 2, in this embodiment, a method for correcting and calculating an influence of operation of a high-temperature economizer on steam turbine heat consumption includes the following steps:

when the high-temperature economizer system is not in operation, the flow rate is Q_IntoTemperature t_IntoThe feed water is heated by a main feed water circuit such as No. 3 high-pressure heater, No. 2 high-pressure heater, No. 1 high-pressure heater and the like in sequence and then enters the economizer, and the temperature of the outlet of each heater is t₃、t₂、t₁… … are provided. After the heat and mass balance calculation is carried out on the corresponding heater, the corresponding steam extraction quantity of the steam turbine is Q₃、Q₂、Q₁… … are provided. The above parameters are selected from the thermal equilibrium map provided by the equipment manufacturer.

After the high-temperature economizer system is put into operation, the water supply flow entering the water supply main circuit and the high-temperature economizer is adjusted through the opening degree of the high-temperature economizer inlet adjusting valve. That is, the flow rate into the main water supply line is Q'_IntoThe outlet temperature and the extraction steam quantity of each heater are changed due to the change of the flow, and the corresponding heater parameters are t'₃、t’₂、t’₁… … with respective extraction flows of Q'₃、Q’₂、Q’₁… … are provided. Flow through the high temperature economizer is Q_{Gao Sheng}The outlet temperature of the high-temperature economizer is t_{Gao Sheng}. The above parameters are derived from those obtained during the testAnd (6) operating the data.

Under the condition that the input heat of the unit is not changed, after the high-temperature economizer is put into operation, the water supply flow through the main path is reduced, so that the steam extraction flow of the corresponding heater is reduced, the work capacity in the cylinder is increased, and the heat consumption of the unit is further reduced.

For a conventional coal-fired unit, 1 extraction and 2 extractions are steam extraction on a high-pressure cylinder of a steam turbine, and 3 extractions are steam extraction on a medium-pressure cylinder of the steam turbine. 1, reducing the extracted steam quantity, increasing the work quantity in the cylinder, including the corresponding work quantities of a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder, and increasing the heat absorption quantity of the cylinder in a reheater; 2, when the extracted steam quantity is reduced, increasing the heat absorption quantity of a reheater and increasing the work quantity of a medium pressure cylinder and a low pressure cylinder; 3, the extracted steam quantity is reduced, and the increased work quantity is 3 work quantities of extraction to the middle discharge flow passage part and the low-pressure cylinder.

Then, the medium-temperature economizer is put into operation, on one hand, the work load of the unit is increased, and on the other hand, the heat input is increased. The method comprises the following specific steps:

the work amount increased by reducing the steam extraction in the section 1 is as follows:

W₁＝(Q₁-Q’₁)*((h₁-h_gp)+(h_zr-h_zp)+(h_dj-h_pq)) (1)

the 1-stage extraction reduces the heat absorption increased in the reheater as follows:

H_z1＝(Q₁-Q′₁)*(h_zc-h_zr) (2)

the work amount increased by reducing the steam extraction in the 2-section is as follows:

W₂＝(Q₂-Q′₂)*((h_zr-h_zp)+(h_dj-h_pq)) (3)

the 2-stage extraction reduces the heat absorption increased in the reheater by:

H_z2＝(Q₂-Q′₂)*(h_zc-h_zr) (4)

the work amount increased by reducing the steam extraction in the 3 sections is as follows:

W₃＝(Q₃-Q′₃)*((h₃-h_zp)+(h_dj-h_pq)) (5)

then, the input heat of the turboset is H, and the generating capacity of the unit without using the high-temperature economizer is W_{Is provided with}The design heat consumption of the steam turbine is as follows:

q_{is provided with}＝H/W_{Is provided with} (6)

The generating capacity of the high-temperature economizer used by the unit is as follows:

W_throw-in＝W_{Is provided with}+W₁+W₂+W₃ (7)

The heat consumption of the steam turbine is as follows:

q_throw-in＝(H+H_z1+H_z2)/W_Throw-in (8)

The rate of change of heat rate is:

in the formula: q₁、Q′₁、Q₂、Q′₂、Q₃、Q′₃The first pumping flow, the second pumping flow and the third pumping flow h before and after the high-temperature economizer is put into use₁、h_zr、h_zp、h_dj、h_pq、h₃Respectively is a first enthalpy extraction value, a reheating steam enthalpy value, a middle exhaust enthalpy value, a low-pressure cylinder steam inlet enthalpy value, a low-pressure cylinder steam exhaust enthalpy value and a three enthalpy extraction value.

h_zc、h_zrThe enthalpy values of the outlet and the inlet of the reheater.

According to the calculation method, under the rated load of the unit, a plurality of main water supply path flow values are given in the water supply flow change range, corresponding heat consumption change rate values are obtained respectively, and corresponding curves are obtained in a numerical fitting mode and used for correction calculation.

Those not described in detail in this specification are well within the skill of the art.

Although the present invention has been described with reference to the above embodiments, it should be understood that the scope of the present invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims (1)

1. A correction calculation method for influence of high-temperature economizer operation on steam turbine heat consumption is characterized by comprising the following steps:

when the high-temperature economizer system is not in operation, the flow rate is Q_IntoTemperature t_IntoThe feed water is heated in a main water supply path by a No. 3 high heater, a No. 2 high heater and a No. 1 high heater … … in sequence and then enters the economizer, and the temperature of the outlet of each heater is t₃、t₂、t₁… …, respectively; after the heat and mass balance calculation is carried out on the corresponding heater, the corresponding steam extraction quantity of the steam turbine is Q₃、Q₂、Q₁… …, respectively; the above parameters are selected from a thermal equilibrium diagram provided by the equipment manufacturer;

after the high-temperature economizer system is put into operation, the water supply flow entering the water supply main circuit and the high-temperature economizer is adjusted through the opening degree of the high-temperature economizer inlet adjusting valve; that is, the flow rate into the main water supply line is Q'_IntoThe temperature and the steam extraction quantity of the outlet of each heater are changed due to the change of the flow, and the corresponding heater parameters are t₃、t′₂t′₁… … with respective extraction flows of Q'₃、Q′₂、Q′₁… …, respectively; flow through the high temperature economizer is Q_{Gao Sheng}The outlet temperature of the high-temperature economizer is t_{Gao Sheng}(ii) a The above parameters are from the operating data obtained during the test;

under the condition that the input heat of the unit is not changed, after the high-temperature economizer is put into operation, the water supply flow through the main path is reduced, so that the steam extraction flow of the corresponding heater is reduced, the work capacity in the cylinder is increased, and the heat consumption of the unit is further reduced;

for a conventional coal-fired unit, 1 extraction and 2 extractions are steam extraction on a high-pressure cylinder of a steam turbine, and 3 extractions are steam extraction on a medium-pressure cylinder of the steam turbine; 1, reducing the extracted steam quantity, increasing the work quantity in the cylinder, including the corresponding work quantities of a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder, and increasing the heat absorption quantity of the cylinder in a reheater; 2, when the extracted steam quantity is reduced, increasing the heat absorption quantity of a reheater and increasing the work quantity of a medium pressure cylinder and a low pressure cylinder; 3, the steam extraction amount is reduced, and the increased work amount is 3 work amounts of extraction to the middle discharge flow passage part and the low pressure cylinder;

then, the medium-temperature economizer is put into operation, on one hand, the work load of the unit is increased, and on the other hand, the heat input is increased; the method comprises the following specific steps:

the work amount increased by reducing the steam extraction in the section 1 is as follows:

W₁＝(Q₁-Q′₁)*((h₁-h_gp)+(h_zr-h_zp)+(h_dj-h_pq)) (1)

the 1-stage extraction reduces the heat absorption increased in the reheater as follows:

H_z1＝(Q₁-Q′₁)*(h_zc-h_zr) (2)

the work amount increased by reducing the steam extraction in the 2-section is as follows:

W₂＝(Q₂-Q′₂)*((h_zr-h_zp)+(h_dj-h_pq)) (3)

the 2-stage extraction reduces the heat absorption increased in the reheater by:

H_z2＝(Q₂-Q′₂)*(h_zc-h_zr) (4)

the work amount increased by reducing the steam extraction in the 3 sections is as follows:

W₃＝(Q₃-Q′₃)*((h₃-h_zp)+(h_dj-h_pq)) (5)

then, the input heat of the turboset is H, and the generating capacity of the unit without using the high-temperature economizer is W_{Is provided with}The design heat consumption of the steam turbine is as follows:

q_{is provided with}＝H/W_{Is provided with} (6)

The generating capacity of the high-temperature economizer used by the unit is as follows:

W_throw-in＝W_{Is provided with}+W₁+W₂+W₃ (7)

The heat consumption of the steam turbine is as follows:

q_throw-in＝(H+H_z1+H_z2)/W_Throw-in (8)

The rate of change of heat rate is:

in the formula: q₁、Q′₁、Q₂、Q₂、Q₃、Q′₃The first pumping flow, the second pumping flow and the third pumping flow h before and after the high-temperature economizer is put into use₁、h_zr、h_zp、h_dj、h_pq、h₃Respectively is a first enthalpy extraction value, a reheat steam enthalpy value, a middle exhaust enthalpy value, a low-pressure cylinder steam inlet enthalpy value, a low-pressure cylinder steam exhaust enthalpy value and a three enthalpy extraction value; h is_zc、h_zrThe enthalpy values of an outlet and an inlet of the reheater;

according to the calculation method, under the rated load of the unit, a plurality of main water supply path flow values are given in the water supply flow change range, corresponding heat consumption change rate values are obtained respectively, and corresponding curves are obtained in a numerical fitting mode and used for correction calculation.

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