A method and device for evaluating the heating economy of a coal-fired power unit

Abstract

The application discloses a kind of based on coal power unit's heat supply economy evaluation method and device, the method includes: the unit of proposed heat supply reconstruction carries out primary performance test, test condition is pure condensation condition, and the unit power supply coal consumption under pure condensation condition is obtained by test calculation;Suppose that unit has carried out heat supply reconstruction, determine unit heat supply;According to the heat supply quantity evaluation thermodynamic system variation quantity obtains main steam flow, main feed water flow and heat rate under heat supply condition;Determine power supply coal consumption under heat supply condition;Determine heat supply coal consumption under heat supply condition;According to power supply coal consumption and heat supply coal consumption under heat supply condition determines comprehensive coal consumption;The application has the advantages that: the heat supply economy evaluation of coal power unit is realized, and whether power plant is carried out heat supply reconstruction provides certain decision support.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat supply energy saving and economy evaluation, and more particularly to a heat supply economy evaluation method and device based on coal-fired generating units. BACKGROUND

[0002] With the continuous development of the national economic and social situation, the "carbon peak and carbon neutral" goal (referred to as "double carbon" goal) proposed by the state requires unprecedented energy saving and carbon reduction efforts of thermal power generating units. At present, thermal power plants are actively carrying out "three-reform linkage" projects mainly in energy saving reform, heat supply reform, and flexibility reform. At present, heat supply reform is the most effective energy saving and carbon reduction measure, and each power generation enterprise also actively carries out heat supply reform according to the needs of surrounding users and its own development.

[0003] At present, for the economic evaluation of the unit after the heat supply reform, the national standard DL / T904-2015 "Calculation method of technical and economic indicators for thermal power plants" mainly uses the method of positive balance to calculate the heat supply coal consumption and the comprehensive coal consumption. This method has low accuracy and can only be used for statistics. In addition, the statistical cycle is long, which cannot meet the real-time economic evaluation demand. Another important deficiency is that this method only calculates and evaluates the economy of the unit after the reform, and cannot provide economic evaluation suggestions for the unit preparing for the reform. Therefore, there is an urgent need for a heat supply economy evaluation method based on coal-fired generating units to evaluate the economy of the unit preparing for the heat supply reform, so as to guide the heat supply reform.

[0004] Chinese patent authorization announcement No. CN108879776B discloses a sustainable development coal-fired generating unit retirement evaluation method, which relates to the field of electric power technology. It is invented to decide whether the coal-fired generating unit should be retired for the sustainable development of the coal-fired generating unit and the single thermal power plant. The method includes: establishing an index system, screening various indexes of the thermal power plant, and comparing with the relevant policy documents of the state to determine whether the thermal power plant meets the retirement conditions; combining the index analysis of regional power balance to obtain the maximum reducible coal-fired generating unit scale of the region; for whether the single thermal power plant should be retired, the heat supply index of the thermal power plant and various standards for the safe and stable operation of the power grid should also be considered. The patent is applied to the decision of the sustainable development of the coal-fired generating unit retirement evaluation, which can better guide the actual decision of the regional coal-fired unit retirement. Although the heat supply index is considered, it does not involve the heat supply economy evaluation of the coal-fired generating unit. SUMMARY

[0005] The technical problem to be solved by the present application is that the prior art lacks a method for evaluating the economy of the unit preparing for the heat supply reform.

[0006] The present application solves the above technical problems by the following technical means: a heat supply economy evaluation method based on coal-fired generating units, which comprises:

[0007] Step one: a unit to be carried out for heating modification of the performance test, test conditions for pure condensing conditions, calculated by test to obtain the unit power supply coal consumption under pure condensing conditions;

[0008] Step two: assuming that the unit has been carried out for heating modification, determine the unit heating capacity; according to the heating capacity of the thermal system to assess the amount of change to obtain the main steam flow, main feed water flow and heat rate under heating conditions;

[0009] Step three: according to the results of step two to determine the heating conditions under the power supply coal consumption;

[0010] Step four: determine the heating conditions under the heating coal consumption;

[0011] Step five: according to the heating conditions under the power supply coal consumption and heating coal consumption to determine the comprehensive coal consumption.

[0012] The present application to the unit to be carried out for heating modification of the unit power supply coal consumption under pure condensing conditions, heating coal consumption under heating conditions and power supply coal consumption and according to the above calculation results to obtain the comprehensive coal consumption, so as to complete the economic evaluation, according to the unit power supply coal consumption under pure condensing conditions, heating conditions under the power supply coal consumption, comprehensive coal consumption and other data, whether to carry out heating modification for power plant to provide certain decision support.

[0013] Further, the step one comprises:

[0014] The formula HR = (W ms H ms +W hr H hr -W fw H fw -W cr H cr -W rhs H rhs -W shs H shs ) / P is used to calculate the heat rate under pure condensing conditions, wherein HR is the heat rate, unit kJ / kWh; W ms is the main steam flow, unit t / h; W fw is the high pressure heater outlet feed water flow, unit t / h; H ms is the main steam enthalpy, unit kJ / kg; H fw is the feed water enthalpy, unit kJ / kg; W cr is the cold reheat flow, unit t / h; W hr is the hot reheat flow, unit t / h; H hr is the hot reheat enthalpy, unit kJ / kg; H cr is the cold reheat enthalpy, unit kJ / kg; W rhs is the reheat desuperheating water flow, unit t / h; H rhsH is the enthalpy of the reheat desuperheating water, unit: kJ / kg; W shs H is the flow of the superheating desuperheating water, unit: t / h; H shs H is the enthalpy of the superheating desuperheating water, unit: kJ / kg; P is the output power of the generator, unit: MW;

[0015] The formula b f = HR / (29308 x η gl x η gd ) x 10 3 / (1-η e ) is used to calculate the power supply coal consumption under the pure condensing condition; wherein, b f is the power supply coal consumption, unit: g / kWh; η gl is the boiler efficiency, unit: no; η gd is the pipeline efficiency, unit: no; η e is the auxiliary power rate, unit: no.

[0016] Further, the step two comprises:

[0017] If the steam is extracted from the high-pressure cylinder exhaust port for heating W grh , since this part of the steam only does work in the high-pressure cylinder, it is extracted for heating here, and under the condition of keeping the power unchanged, the main steam flow is increased by [1-(high-pressure cylinder power / high, medium and low-pressure cylinder power)]*W grh , to obtain the new main steam flow W msn ;

[0018] Or, assuming that the steam is extracted from the medium-pressure cylinder exhaust port for heating W gri , since this part of the steam does work in the high and medium-pressure cylinders, it is extracted for heating here, and under the condition of keeping the power unchanged, the main steam flow is increased by [1-(high and medium-pressure cylinder power / high, medium and low-pressure cylinder power)]*W gri , to obtain the new main steam flow W msn ;

[0019] The main steam flow W msn =(1-γ / 100)*W fwn ; wherein, γ is the unknown leakage rate, unit: no; W fwn is the main feed water flow after the transformation, unit: t / h. The main feed water flow W fwn after the transformation is obtained by reverse calculation under the assumption that the unknown leakage rate is unchanged, and then the new cold reflow W crn , the hot reflow W hrn , and finally the heat consumption rate HR n =(W msn H ms +W hrn Hhr -W fwn H fw -W crn H cr -W rhs H rhs -W shs H shs -W grh H grh -W gri H gri ) / P, wherein H grh is the enthalpy value of high-pressure cylinder exhaust steam extraction, unit kJ / kg; H gri is the enthalpy value of medium-pressure cylinder exhaust steam extraction, unit kJ / kg.

[0020] Further, the step three comprises:

[0021] Supposing that the unit pipeline efficiency, boiler efficiency and auxiliary power rate remain unchanged under the pure condensation condition and the heat supply condition, the coal consumption for power supply after the unit heat supply reconstruction is calculated through the formula b fd = HR n / (29308*eta gl *eta gd )*10 3 / (1-eta e ).

[0022] Further, the step four comprises:

[0023] The heat supply coal consumption is obtained through the formula b fr = 34.12 / (eta w *eta gl *eta gd ), wherein eta w is the heat network heater thermal efficiency, unitless; and 34.12 is the heat equivalent value coefficient for standard coal.

[0024] Further, the step five comprises:

[0025] The comprehensive coal consumption is obtained through the formula b fz = (b fd *P + (W grh H grh + W gri H gri )*b fr / 10 3 ) / P.

[0026] The application further provides a heat supply economy evaluation device based on a coal-fired unit, which comprises:

[0027] The performance test module is used for performing a performance test on the unit to be reformed for heat supply, and the test working condition is pure condensation working condition, and the unit power supply coal consumption under the pure condensation working condition is obtained through test calculation;

[0028] The heat supply reform result calculation module is used for assuming that the unit has been reformed for heat supply, determining the unit heat supply amount, and obtaining the main steam flow, the main feed water flow and the heat consumption rate under the heat supply working condition according to the heat supply amount and the heat supply system change amount;

[0029] The power supply coal consumption obtaining module is used for determining the power supply coal consumption under the heat supply working condition according to the result of step two;

[0030] The heat supply coal consumption obtaining module is used for determining the heat supply coal consumption under the heat supply working condition;

[0031] The comprehensive coal consumption obtaining module is used for determining the comprehensive coal consumption according to the power supply coal consumption and the heat supply coal consumption under the heat supply working condition.

[0032] Further, the performance test module is further used for:

[0033] The heat consumption rate under the pure condensation working condition is calculated through the formula HR=(W ms H ms +W hr H hr -W fw H fw -W cr H cr -W rhs H rhs -W shs H shs ) / P, wherein W ms is the main steam flow; W fw is the high-pressure heater outlet feed water flow; H ms is the main steam enthalpy value; H fw is the feed water enthalpy value; W cr is the cold reheat flow; W hr is the hot reheat flow; H hr is the hot reheat enthalpy value; H cr is the cold reheat enthalpy value; W rhs is the reheat desuperheating water flow; H rhs is the reheat desuperheating water enthalpy value; W shs is the superheating desuperheating water flow; H shs is the superheating desuperheating water enthalpy value; and P is the generator output power;

[0034] The formula b f =HR / (29308×η gl ×η gd )×10 3 / (1-η e) to calculate the coal consumption of the unit under the pure condensing condition; wherein, b f is the coal consumption for power supply; HR is the heat rate of the unit; η gl is the boiler efficiency; η gd is the pipeline efficiency, η e is the auxiliary power rate.

[0035] Further, the heat supply reconstruction result calculation module is further used to:

[0036] If after the heat supply reconstruction, it is assumed that steam W grh is extracted from the high-pressure cylinder exhaust port for heat supply, since this part of steam only does work in the high-pressure cylinder and is extracted for heat supply here, under the condition that the power remains unchanged, it is equivalent to the main steam flow increasing by [1-(high-pressure cylinder power / high, medium and low-pressure cylinder power sum)]*W grh , to obtain the new main steam flow W msn ;

[0037] Or, it is assumed that steam W gri is extracted from the medium-pressure cylinder exhaust port for heat supply, since this part of steam does work in the high and medium-pressure cylinders and is extracted for heat supply here, under the condition that the power remains unchanged, it is equivalent to the main steam flow increasing by [1-(high and medium-pressure cylinder power sum / high, medium and low-pressure cylinder power sum)]*W gri , to obtain the new main steam flow W msn ;

[0038] The main steam flow W msn =(1-γ / 100)*W fwn ; wherein, γ is the unknown leakage rate, unitless; W fwn is the main feed water flow after the reconstruction, unit t / h. Through the assumption that the unknown leakage rate remains unchanged, the improved main feed water flow W fwn is obtained by back calculation, and then the new cold reheat flow W crn , the hot reheat flow W hrn , and finally the heat rate HR n under the heat supply condition are calculated. msn =(W ms H hrn +W hr H fwn -W fw H crn -W cr H rhs -W rhs H shs -W shs H grh -W grh H gri -W gri ) / P, wherein, H grhis the enthalpy value of steam extraction at the exhaust port of the high-pressure cylinder; gri is the enthalpy value of steam extraction at the exhaust port of the medium-pressure cylinder.

[0039] Further, the power supply coal consumption acquisition module is further used for:

[0040] Supposing that the unit pipeline efficiency, the boiler efficiency and the auxiliary power rate remain unchanged under the pure condensation condition and the heat supply condition, the power supply coal consumption of the unit after the heat supply reconstruction is calculated through the formula b fd = HR n / (29308*eta gl *eta gd )*10 3 / (1-eta e ).

[0041] Further, the heat supply coal consumption acquisition module is further used for:

[0042] The heat supply coal consumption is acquired through the formula b fr =34.12 / (eta w *eta gl *eta gd ), wherein eta w is the heat network heater thermal efficiency, and 34.12 is the heat equivalent value coefficient of standard coal.

[0043] Further, the comprehensive coal consumption acquisition module is further used for:

[0044] The comprehensive coal consumption is acquired through the formula b fz =(b fd *P+(W grh H grh +W gri H gri )*b fr / 10 3 ) / P.

[0045] The present application has the advantages that: the present application calculates the unit power supply coal consumption under the pure condensation condition, the heat supply coal consumption under the heat supply condition and the power supply coal consumption, and obtains the comprehensive coal consumption according to the above calculation results, so as to complete the economic evaluation, and according to the unit power supply coal consumption under the pure condensation condition, the heat supply coal consumption under the heat supply condition, the comprehensive coal consumption and other data, certain decision support is provided for whether the power plant is reconstructed for heat supply. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a flow chart of a heat supply economic evaluation method based on a coal-fired unit disclosed by the embodiment of the present application. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] like Figure 1 As shown, a method for evaluating the economic efficiency of heating based on coal-fired power units is provided, the method comprising:

[0050] S1: Conduct a performance test on the unit to be retrofitted for heating. The test condition is pure condensing operation. The main results of the performance test include the unit's heat rate, boiler efficiency, and plant power consumption rate. The coal consumption for power supply under pure condensing operation is calculated through the test. The specific process is as follows:

[0051] (1.1) Using the formula HR=(W ms H ms +W hr H hr -W fw H fw -W cr H cr -W rhs H rhs -W shs H shs The heat rate is calculated using W / P. Where: W ms – Main steam flow rate, calculated from the measured main condensate flow rate through heat balance between the deaerator and high-pressure heater, yields the high-pressure heater outlet feedwater flow rate, in units of t / h; W fw – High-pressure heater outlet feedwater flow rate, in t / h; H ms – Main steam enthalpy, unit kJ / kg; H fw – Enthalpy of feedwater, unit: kJ / kg; W cr – Cold reheat flow rate, in t / h; W hr –Heat reheat flow rate, in t / h; H hr – Enthalpy of reheating, in kJ / kg; H cr – Enthalpy of cold reheat, unit: kJ / kg; W rhs – Reheat desuperheating water flow rate, in t / h; H rhs – Enthalpy of reheated cooling water, in kJ / kg, W shs – Superheated desuperheating water flow rate, in t / h. For supercritical and above type units, this item is 0; H shs- enthalpy of superheated desuperheating water, unit kJ / kg, P - output power of generator, unit MW.

[0052] (1.2) by formula b f = HR / (29308 x η gl x η gd ) x 10 3 / (1-η e ) to calculate the coal consumption of the unit. In the formula: b f is the coal consumption, unit g / kWh; HR is the heat rate of the unit, unit kJ / kWh; η gl is the boiler efficiency; η gd is the pipeline efficiency. The calculation can obtain the coal consumption of the unit under the pure condensing condition b f .

[0053] S2: assuming that the unit has been heat-supply modified, determine the heat-supply of the unit; according to the heat-supply, evaluate the change of the thermal system to obtain the main steam flow, the main feed water flow and the heat rate under the heat-supply condition; the specific process is:

[0054] Assuming that the heat-supply after the heat-supply modification is W gr t / h, the heat-supply extraction steam can be extracted from the high-pressure cylinder exhaust port or from the medium-pressure cylinder exhaust port. The generator power P remains unchanged, and as the heat-supply extraction amount continuously increases from 0, the whole thermal system changes, such as the steam extracted from the high-pressure cylinder exhaust port is extracted for heat-supply after doing work in the high-pressure cylinder and is not doing work in the medium-pressure cylinder and the low-pressure cylinder, while the steam extracted from the medium-pressure cylinder exhaust port is extracted for heat-supply after doing work in the high-pressure cylinder and the medium-pressure cylinder and is not doing work in the low-pressure cylinder. Now the main steam amount and the feed water flow in the thermal system after the heat-supply modification are evaluated to obtain the new heat rate HR n .

[0055] (2.1) assuming that the steam extracted from the high-pressure cylinder exhaust port is for heat-supply W grh t / h, since this part of steam only does work in the high-pressure cylinder, it is extracted for heat-supply at this place, and in the case of keeping the power unchanged, it is equivalent to that the main steam flow increases [1-(high-pressure cylinder power / sum of high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder power)]*W grh t / h. The proportion of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder power in the total power of different types of units is certain, for example, the proportion of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder power in the total power of a 300MW subcritical unit is 30%, 30% and 40% respectively. This data can be found in the characteristic data provided by the manufacturer.

[0056] (2.2) similarly, assuming that the steam extracted from the medium-pressure cylinder exhaust port is for heat-supply W grit / h, since the part of steam is extracted from the high pressure cylinder and the medium pressure cylinder to do work, which is equivalent to the increase of the main steam flow [1-(the sum of the high pressure cylinder and the medium pressure cylinder power / the sum of the high pressure cylinder, the medium pressure cylinder and the low pressure cylinder power)]*W gri t / h.

[0057] (2.3) The new main steam flow W can be obtained through calculation after extracting the steam from the high pressure cylinder and the medium pressure cylinder msn , the main steam flow W msn = (1-γ / 100)*W fwn ; wherein, γ is the unknown leakage rate, unitless; W fwn is the main feed water flow after the transformation, unit t / h. Through the assumption of the unchanged unknown leakage rate, the improved main feed water flow W fwn can be obtained by backstepping, and thus the new cold reheat flow W crn and the hot reheat flow W hrn can be calculated, and the heat rate can be calculated through the formula HR n = (W msn H ms +W hrn H hr -W fwn H fw -W crn H cr -W rhs H rhs -W shs H shs -W grh H grh -W gri H gri ) / P. In the formula: H grh is the enthalpy value of the steam extracted from the high pressure cylinder, unit kJ / kg; H gri is the enthalpy value of the steam extracted from the medium pressure cylinder, unit kJ / kg.

[0058] S3: determine the power supply coal consumption under the heating condition according to the result of S2; the specific process is:

[0059] Assuming that the unit pipeline efficiency, the boiler efficiency and the auxiliary power rate remain basically unchanged under the pure condensation condition and the heating condition, the power supply coal consumption b fd of the unit after the heating transformation can be calculated through the formula b n = HR gl / (29308×η gd ×η 3 )×10 e / (1-η fd ), unit g / kWh.

[0060] S4: Determine the coal consumption for heating under heating conditions; the specific process is as follows:

[0061] According to the national standard GB / T2589-2008 "General Rules for Calculation of Comprehensive Energy Consumption", the coefficient for converting thermal equivalent value to standard coal is 34.12 kg / kJ. The coal consumption for heating, b, can then be calculated. fr =34.12 / (η) w ×η gl ×η gd ), where b fr Coal consumption for heating, unit: kg / kJ; η w This refers to the thermal efficiency of the heating network heater; no unit is provided.

[0062] S5: Determine the comprehensive coal consumption based on the coal consumption for power supply and heating under heating conditions. The specific process is as follows:

[0063] Based on the above coal consumption for power supply and heating, the comprehensive coal consumption b of the power plant under heating conditions can be calculated. fz =(b fd *P+(W grh H grh +W gri H gri )*b fr / 10 3 ) / P, where b fz This represents the total coal consumption of the power plant, expressed in g / kWh.

[0064] According to the comprehensive coal consumption of the power plant after the heating system renovation (b) fz Before the upgrade, the coal consumption for power supply of the unit under pure condensing operation was b. f and the standard coal unit price Q c (Unit: Yuan / t), Heat Supply (W) grh +W gri ), Hot Price Q r (Unit: Yuan / t), Calculate:

[0065] (1) The increase in coal consumption cost per hour due to increased heating supply, Y1 = (b fz -b f )*P*Q c / 10 3 ;

[0066] (2)(2) The extra income per hour due to increased heating supply Y2=(W grh +W gri )*Q r .

[0067] To achieve profitability, Y2 > Y1, then Q r >(b fz -b f )*P*Q c / 103 / (W grh +W gri In other words, the heating price should not be less than the value obtained from the above formula when setting the price, so as to achieve profitability during operation. Therefore, by calculating data such as coal consumption for power generation and comprehensive coal consumption under heating conditions using the method provided by this invention, certain decision support can be provided for power plants to decide whether to carry out heating system renovations.

[0068] Through the above technical solutions, this invention calculates the coal consumption for power generation under pure condensing conditions, the coal consumption for heating conditions, and the coal consumption for power generation for units to be retrofitted for heating, and derives the comprehensive coal consumption based on the calculation results, thereby completing the economic evaluation. Based on the data such as the coal consumption for power generation under pure condensing conditions, the coal consumption for power generation under heating conditions, and the comprehensive coal consumption, it provides certain decision support for power plants on whether to carry out heating retrofits, meeting the needs of power generation enterprises for economic evaluation of heating retrofits.

[0069] Example 2

[0070] Based on Embodiment 1, Embodiment 2 of the present invention also provides a heating economic evaluation device based on coal-fired power units, the device comprising:

[0071] The performance test module is used to conduct a performance test on the unit to be retrofitted for heating. The test condition is pure condensing condition. The coal consumption for power supply of the unit under pure condensing condition is calculated through the test.

[0072] The heating system renovation result calculation module is used to determine the unit's heating capacity by assuming that the unit has undergone heating system renovation; and to obtain the main steam flow, main feedwater flow and heat rate under heating conditions by assessing the changes in the thermal system based on the heating capacity.

[0073] The coal consumption acquisition module for power supply is used to determine the coal consumption for power supply under heating conditions based on the results of step two.

[0074] The heating coal consumption acquisition module is used to determine the heating coal consumption under heating conditions.

[0075] The comprehensive coal consumption acquisition module is used to determine the comprehensive coal consumption based on the coal consumption for power supply and heating under heating conditions.

[0076] Specifically, the performance testing module is also used for:

[0077] Using the formula HR=(W) ms H ms +W hr H hr -W fw H fw -W cr H cr -W rhs H rhs -W shs Hshs ) / P, wherein W ms is the main steam flow rate; W fw is the high-pressure heater outlet feed water flow rate; H ms is the main steam enthalpy; H fw is the feed water enthalpy; W cr is the cold reheat flow rate; W hr is the hot reheat flow rate; H hr is the hot reheat enthalpy; H cr is the cold reheat enthalpy; W rhs is the reheat letdown water flow rate; H rhs is the reheat letdown water enthalpy; W shs is the superheat letdown water flow rate; H shs is the superheat letdown water enthalpy; and P is the generator output power.

[0078] The unit power supply coal consumption under the pure condensing condition is calculated by the formula b f = HR / (29308 x η gl x η gd ) x 10 3 / (1 - η e ), wherein b f is the power supply coal consumption; HR is the unit heat consumption; η gl is the boiler efficiency; η gd is the pipeline efficiency, and η e is the auxiliary power rate.

[0079] More specifically, the heating reform result calculation module is further configured to:

[0080] If steam is extracted from the high-pressure cylinder exhaust port for heating after the heating reform W grh , since the steam only does work in the high-pressure cylinder, the steam is extracted for heating at this point, and under the condition that the power remains unchanged, the main steam flow rate is increased by [1 - (high-pressure cylinder power / sum of high, medium, and low-pressure cylinder power)] * W grh , to obtain a new main steam flow rate W msn ;

[0081] Alternatively, assuming that steam is extracted from the medium-pressure cylinder exhaust port for heating W gri , since the steam does work in the high and medium-pressure cylinders, the steam is extracted for heating at this point, and under the condition that the power remains unchanged, the main steam flow rate is increased by [1 - (sum of high and medium-pressure cylinder power / sum of high, medium, and low-pressure cylinder power)] * W gri , to obtain a new main steam flow rate W msn ;

[0082] The main steam flow rate W msn = (1 - γ / 100) * W fwn; wherein, γ is unknown leakage rate, unit is null; W fwn is the improved main feed water flow, unit is t / h. The improved main feed water flow W fwn is obtained by backstepping through the assumption that the unknown leakage rate is constant crn , the new cold reflow W hrn is calculated n , the heat reflow W msn is calculated ms , the heat reflow W hrn is calculated hr , the heat reflow W fwn is calculated fw , the heat reflow W crn is calculated cr , the heat reflow W rhs is calculated rhs , the heat reflow W shs is calculated shs , the heat reflow W grh is calculated grh , the heat reflow W gri is calculated gri , the heat reflow W grh is calculated gri , the heat reflow W fd is calculated n , the heat reflow W gl is calculated gd , the heat reflow W 3 is calculated e , the heat reflow W fr is calculated w , the heat reflow W gl is calculated gd , the heat reflow W w is calculated fz , the heat reflow W fd is calculated grh

[0083] More specifically, the power supply coal consumption obtaining module is further configured to:

[0084] Assuming that the unit pipeline efficiency, boiler efficiency and auxiliary power rate remain unchanged under the pure condensing condition and the heating condition, the power supply coal consumption after the unit heating reconstruction is calculated through the formula b fd = HR n / (29308×η gl ×η gd )×10 3 / (1-η e ).

[0085] More specifically, the heating coal consumption obtaining module is further configured to:

[0086] The heating coal consumption is obtained through the formula b fr = 34.12 / (η w ×η gl ×η gd ), wherein η w is the heat efficiency of the heat network heater, and 34.12 is the standard coal coefficient of the heat equivalent value.

[0087] More specifically, the comprehensive coal consumption obtaining module is further configured to:

[0088] The comprehensive coal consumption is obtained through the formula b fz =(b fd *P+(W grhH grh +W gri H gri )*b fr / 10 3 ) / P get the comprehensive coal consumption.

[0089] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the heating economy of a coal-based power unit, characterized in that, The method comprises: Step one: a performance test is conducted on the unit to be heat-supply modified, the test working condition is pure condensation working condition, and the unit power supply coal consumption under the pure condensation working condition is obtained through test calculation; Using the formula HR=(W) ms H ms +W hr H hr -W fw H fw -W cr H cr -W rhs H rhs -W shs H shs The heat rate of the unit under pure condensing conditions is calculated as W / P. ms Main steam flow rate; W fw H is the feedwater flow rate at the outlet of the high-pressure heater. ms Main steam enthalpy; H fw For water supply enthalpy; W cr For cold reheat flow; W hr For heat reheat flow rate; H hr Enthalpy of reheat; H cr W is the enthalpy value for cold reheating. rhs For reheat desuperheating water flow rate; H rhs W represents the enthalpy of the reheat cooling water. shs For superheated desuperheating water flow rate; H shs P represents the enthalpy of the superheated desuperheating water; P represents the generator output power. The net coal consumption of the unit under the pure condensing condition is calculated by the formula b f = HR / (29308 x η gl x η gd ) x 10 3 / (1-η e ); wherein, b f is the net coal consumption; HR is the heat rate of the unit; η gl is the boiler efficiency; η gd is the pipeline efficiency, and η e is the auxiliary power rate. Step two: it is assumed that the unit has been heat-supply modified, the unit heat supply is determined, the main steam flow, the main feed water flow and the heat rate under the heat supply working condition are obtained according to the heat supply variation of the heat supply system; If the steam extracted from the high pressure cylinder exhaust port for heating W grh , since this part of steam only does work in the high pressure cylinder, where it is extracted for heating, under the condition of keeping the power unchanged, it is equivalent to the main steam flow increasing [1-(high pressure cylinder power / sum of high, medium and low pressure cylinder power)]*W grh , the new main steam flow W msn ; Or, assume that steam is extracted from the IP cylinder exhaust for heating W gri Since this part of steam does work in the HP and IP cylinders, it is extracted for heating here, which is equivalent to the increase of the main steam flow [1-(the sum of HP and IP cylinder power / the sum of HP, IP and LP cylinder power)]*W gri , to get the new main steam flow W msn ; The improved main feed water flow W is obtained by back calculation through the assumption that the unknown leakage rate is unchanged fwn Then the new cold reflow W is calculated crn , the hot reflow W hrn Finally, the heat rate HR under the heat supply condition is obtained n =(W msn H ms +W hrn H hr -W fwn H fw -W crn H cr -W rhs H rhs -W shs H shs -W grh H grh -W gri H gri ) / P, wherein H grh is the enthalpy value of the extraction steam at the exhaust port of the high-pressure cylinder; H gri is the enthalpy value of the extraction steam at the exhaust port of the medium-pressure cylinder; Step three: the power supply coal consumption under the heat supply working condition is determined according to the result of step two; Step four: the heat supply coal consumption under the heat supply working condition is determined; Step five: the comprehensive coal consumption is determined according to the power supply coal consumption and the heat supply coal consumption under the heat supply working condition.

2. The method for evaluating the heat supply economy of a coal-based power unit according to claim 1, characterized in that, The step three comprises: Assuming that the unit is in the pure condensing condition and the heating condition, the unit pipe efficiency, boiler efficiency and auxiliary power rate remain unchanged, through the formula b fd = HR n / (29308×η gl ×η gd )×10 3 / (1-η e ) to calculate the coal consumption of the unit after the heating modification.

3. The method for evaluating the heat supply economy of a coal-based power unit according to claim 2, characterized in that, The step four comprises: The heating coal consumption is obtained by formula b fr = 34.12 / (η w × η gl × η gd ), wherein η w is the heat efficiency of the heat network heater, and 34.12 is the standard coal coefficient of the heat equivalent value.

4. The method for evaluating the heat supply economy of a coal-based power unit according to claim 3, characterized in that, The step five comprises: By formula b fz = (b fd * P + (W grh H grh + W gri H gri ) * b fr / 10 3 ) / P to obtain the comprehensive coal consumption.

5. A heating economic evaluation device based on coal-fired power units, characterized in that, The device comprises: a performance test module, configured to conduct a performance test on the unit to be heat-supply modified, the test working condition is pure condensation working condition, and the unit power supply coal consumption under the pure condensation working condition is obtained through test calculation; HR = (W ms H ms + W hr H hr - W fw H fw - W cr H cr - W rhs H rhs - W shs H shs ) / P ms fw ms fw cr hr hr cr rhs rhs shs shs wherein W ms is the main steam flow rate; W fw is the high-pressure heater outlet feed water flow rate; H ms is the main steam enthalpy; H fw is the feed water enthalpy; W cr is the cold reheat flow rate; W hr is the hot reheat flow rate; H hr is the hot reheat enthalpy; H cr is the cold reheat enthalpy; W rhs is the reheat attemperating water flow rate; H rhs is the reheat attemperating water enthalpy; W shs is the superheating attemperating water flow rate; H shs is the superheating attemperating water enthalpy; and P is the generator output power. The formula b f = HR / (29308 x η gl x η gd ) x 10 3 / (1-η e ) is used to calculate the coal consumption of the unit under the pure condensing condition; wherein, b f is the coal consumption; HR is the heat rate of the unit; η gl is the boiler efficiency; η gd is the pipeline efficiency, η e is the auxiliary power rate; a heat supply modification result calculation module, configured to assume that the unit has been heat-supply modified, determine the unit heat supply, and obtain the main steam flow, the main feed water flow and the heat rate under the heat supply working condition according to the heat supply variation of the heat supply system; If the steam extracted from the high pressure cylinder exhaust port for heating W grh , since this part of steam only does work in the high pressure cylinder, where it is extracted for heating, under the condition of keeping the power unchanged, it is equivalent to the main steam flow increasing [1-(high pressure cylinder power / sum of high, medium and low pressure cylinder power)]*W grh , the new main steam flow W msn ; Or, assume that steam is extracted from the IP cylinder exhaust for heating W gri Since this part of steam does work in the HP and IP cylinders, it is extracted for heating here, which is equivalent to the increase of the main steam flow [1-(the sum of HP and IP cylinder power / the sum of HP, IP and LP cylinder power)]*W gri , to get the new main steam flow W msn ; The improved main feed water flow W is obtained by back calculation through the assumption that the unknown leakage rate is unchanged fwn Then the new cold reflow W is calculated crn , the hot reflow W hrn Finally, the heat rate HR under the heat supply condition is obtained n =(W msn H ms +W hrn H hr -W fwn H fw -W crn H cr -W rhs H rhs -W shs H shs -W grh H grh -W gri H gri ) / P, wherein H grh is the enthalpy value of the extraction steam at the exhaust port of the high-pressure cylinder; H gri is the enthalpy value of the extraction steam at the exhaust port of the medium-pressure cylinder; a power supply coal consumption obtaining module, configured to determine the power supply coal consumption under the heat supply working condition according to the result of step two; a heat supply coal consumption obtaining module, configured to determine the heat supply coal consumption under the heat supply working condition; a comprehensive coal consumption obtaining module, configured to determine the comprehensive coal consumption according to the power supply coal consumption and the heat supply coal consumption under the heat supply working condition.

6. The device for evaluating the heat supply economy of a coal-based power unit according to claim 5, characterized in that, The power supply coal consumption obtaining module is further configured to: Assuming that the unit is in the pure condensing condition and the heating condition, the unit pipe efficiency, boiler efficiency and auxiliary power rate remain unchanged, through the formula b fd = HR n / (29308×η gl ×η gd )×10 3 / (1-η e ) to calculate the coal consumption of the unit after the heating modification.

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