Method for evaluating state of steam turbine of water feeding pump of thermal power plant

Abstract

The invention discloses a thermal power plant feed pump turbine state evaluation method, and belongs to the technical field of rotary power equipment state monitoring and maintenance management. The method comprises the following steps: extracting characteristic parameters of steam flow, bearing metal temperature, lubricating oil pressure, oil return temperature, bearing vibration, rotating speed, axial displacement and steam exhaust pressure of the water feed pump turbine; according to the characteristic parameters, a high-dimensional original characteristic space is expressed by a low-dimensional characteristic space through a transformation method, and representative and effective characteristic quantities are found out; state characteristic parameters are determined through the characteristic quantity; state evaluation is carried out on the state characteristic parameters through a variable weight comprehensive evaluation model, and an index weight function is determined; determining the state of the feed pump turbine according to the index weight function; and responding to the state of the feed pump turbine, and recommending a maintenance strategy according to thermal economy analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of thermal power plant feed water pump turbine condition evaluation method, belong to rotating power equipment condition monitoring and maintenance management technical field. BACKGROUND

[0002] As one of important auxiliary systems of thermal power plant, the feed water system of most units currently mainly has feed water pump and feed water pump turbine unit, which bears the continuous supply of feed water to the boiler and provides desuperheating water to the boiler reheater and the high-pressure bypass device of steam turbine. Nowadays, many units are only provided with a single 100% capacity feed water pump set, and its reliability is particularly important. Once the feed water system is abnormal, it will directly lead to shutdown, which seriously affects the safety and economy of the unit. With the continuous increase of new energy power generation proportion, the power supply structure has undergone profound changes, and frequent wide-load adjustment of coal-fired generating units has become a normal state, which puts forward higher requirements for the safe and stable operation of key equipment of power plant, especially for feed water pump turbine. The adjustment range is wider and the adjustment frequency is more frequent, so the reliability and economic operation are more and more prominent.

[0003] However, at present, the maintenance plan of the feed water system of many coal-fired power plants is still implemented according to experience. This maintenance mode has some problems, mainly as follows: (1) The running time of calendar days is used to determine the maintenance cycle, without considering the actual operation characteristics of the unit, and there is over-maintenance; (2) Single-dimensional state evaluation is carried out, and the traditional method is mainly based on vibration monitoring and other physical parameters to evaluate the reliability, without quantitative analysis of economic indicators such as equipment maintenance cost and energy loss, which makes it difficult to balance safety and economy in operation and maintenance decision-making; (3) Usually, maintenance is carried out at the same time as the main equipment maintenance, without considering the deterioration law of the thermal performance of the unit and the economic efficiency of the maintenance, and the maintenance work is organized before the feed water system is in normal operation. This kind of unified maintenance interval regardless of the type of equipment, manufacturer and operation reliability of the equipment, etc. has some unscientific and unreasonable situations.

[0004] Facing the change of power supply structure, the utilization hours of coal-fired units decrease year by year, and in the areas where new energy is abundant, coal-fired units are often in shutdown state. Arranging maintenance cycle according to calendar years leads to great waste of resources. In addition, due to factors such as rising coal prices, the profitability of power generation enterprises is weakened. Under the condition that the equipment is in normal operation, it is an effective way for power generation enterprises to reduce costs and increase efficiency to reasonably optimize and adjust the maintenance cycle by comprehensively judging the reliability and economy of the equipment. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a kind of thermal power plant feed water pump turbine condition evaluation method; To achieve the above-mentioned purpose / to solve the above-mentioned technical problems, the present application is realized by adopting the following technical solutions: A state evaluation method for a feed water pump turbine of a thermal power plant, the method comprising: extracting characteristic parameters of the feed water pump turbine, including steam flow, bearing metal temperature, lubricating oil pressure, oil return temperature, bearing vibration, rotating speed, axial displacement, and exhaust pressure; transforming the high-dimensional original characteristic space into a low-dimensional characteristic space to find representative and effective characteristic quantities; using the degradation degree of the state threshold value as an evaluation index of the operating state; evaluating the state characteristic parameters by a variable weight comprehensive evaluation model to determine an index weight function; calculating a plurality of initial weight values and an optimal order relation of the importance evaluation index of each state parameter by the weight function to obtain each importance evaluation index value; and determining the state of the feed water pump turbine according to the importance evaluation index value; in response to the reliability state of the feed water pump turbine, fusing a thermal economic analysis to recommend a maintenance strategy.

[0006] Optionally, the state evaluation index includes a fixed state threshold value and a statistical state threshold value; the fixed state threshold value is determined by comparing the value representing the state of the equipment measured at the same position of the feed water pump turbine or according to certain requirements with a corresponding judgment standard value to evaluate the operating state; the statistical state threshold value is determined by a formula, and the mean value of the monitoring parameters is calculated and the standard deviation : ; wherein: is the state threshold value of the i-th level, which is determined according to the importance and use of the equipment.

[0007] Optionally, the state of the feed water pump turbine includes a good state, a better state, a general state, and a fault state, wherein: the good state means that the feed water pump turbine can continue to be used and is suitable for long-term operation; the better state means that the feed water pump turbine has abnormal signs, and can be operated for a period of time before appropriate maintenance time; the general state means that the feed water pump turbine has relatively serious abnormal signs, and measures should be taken for maintenance or adjustment of the operation mode; ​The fault state: refers to the feed water pump turbine has serious abnormal signs, can not run for a long time, reached the shutdown maintenance limit.

[0008] Optionally, the thermal economic analysis includes maintenance cost and maintenance benefit, the maintenance cost includes: The labor cost (C1): ; Indicates the number of maintenance personnel, units are; Indicates the maintenance time, units are hours; Indicates the labor rate, units are yuan / person·hour; The maintenance cost calculation includes spare parts and consumables cost (C2): ; Indicates the quantity of spare parts, units are; Indicates the unit price of spare parts, units are yuan / unit; The maintenance cost is: .

[0009] Optionally, the maintenance benefit includes that the feed water pump turbine improves efficiency through maintenance, the thermal economic benefit caused by the change of efficiency; the thermal economic benefit includes the direct coal consumption reduction and the reduced fuel cost of the indirect coal consumption reduction.

[0010] Optionally, the direct coal consumption reduction Is due to the operation efficiency of the feed water pump turbine being improved through the maintenance activity, the steam consumption required is reduced, the steam consumption reduction leads to the coal consumption reduction, thereby generating the cost saving amount; The direct steam consumption is from: extraction equivalent enthalpy drop And extraction efficiency : ; ; Indicates the specific enthalpy of the main steam turbine new steam and Indicates the specific entropy of the main steam turbine new steam; Indicates the extraction point parameter; Indicates the condenser temperature; The power required by the feed water pump turbine to drive the feed water pump The relationship between the steam consumption: ; If the efficiency of the feed water pump turbine rises from to , the steam consumption is reduced by ; The corresponding change in heat of steam is ; The reduction in direct coal consumption is .

[0011] Optionally, the reduction in indirect coal consumption is the saving in indirect coal consumption cost caused by the increased power generation of the main steam turbine due to the improved efficiency of the feed water pump turbine.

[0012] Optionally, the indirect coal consumption includes: The reduced steam extraction of the main steam turbine and the increased power generation: ; The reduced coal consumption of the increased power generation, the reduction in indirect coal consumption: ; Indicates the low calorific value of coal.

[0013] Optionally, the total coal consumption reduction of the direct coal consumption and the indirect coal consumption is: ; Optionally, the reduced fuel cost of the reduced direct coal consumption and the reduced indirect coal consumption is the maintenance benefit; ; Indicates the price of coal entering the plant; Indicates the running time; Indicates the total power of the power plant.

[0014] Compared with the prior art, the beneficial effects achieved by the present application are: 1. The feed water pump turbine adopts a reliability and economy multi-element evaluation method for condition-based maintenance, realizing multi-dimensional synergistic effect, and the two-dimensional evaluation mechanism avoids the limitations of single index evaluation, more comprehensively evaluates the effect of maintenance strategy, and makes the maintenance decision from experience-driven to data-driven.

[0015] 2. From the perspective of reliability, multi-element evaluation significantly improves the accuracy and timeliness of fault early warning. By establishing a failure mode and effect analysis framework, the system can quantify the contribution of different component failures to the overall reliability of the unit, and prioritize high-risk nodes.

[0016] 3. From the economic point of view, the fine consideration of the cost factor is realized, the direct cost is included in the unified analysis as a kind of maintenance decision reference, on the basis of the unit maintenance operation, auxiliary operation production decision is made, the decision mode based on the whole life cycle cost analysis effectively solves the problem of insufficient economic evaluation of traditional management in technical transformation project, and the maintenance resource allocation is optimized.

[0017] 4. Promote the diversified transformation of equipment management, realize the reference comparison under the operation load and maintenance strategy through the reliability and economy double evaluation technology, and provide quantitative basis for the feed pump turbine maintenance cycle. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 Fig. 1 shows the state evaluation principle diagram of the feed pump turbine of the embodiment of the present application; Fig. 2 Fig. 2 shows the state evaluation work flow diagram of the feed pump turbine of the present application. DETAILED DESCRIPTION

[0019] In order to make the technical means, creative characteristics and purposes and effects realized by the present application easy to understand, the present application is further described below in combination with specific embodiments.

[0020] In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0021] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0022] AsFigs. 1-2 As shown, a thermal power plant feed water pump turbine state evaluation method is disclosed, and the steps are as follows: The characteristic parameters of the steam flow, bearing metal temperature, lubricating oil pressure, oil return temperature, bearing vibration, rotating speed, axial displacement, and exhaust pressure of the feed water pump turbine are extracted; The characteristic parameters related to the real-time health information of the feed water pump turbine are transformed to express the high-dimensional original characteristic space with a low-dimensional characteristic space, and representative and effective characteristic quantities are found out; The deterioration degree of the state threshold value is used as an evaluation index of the operating state of the characteristic quantity; The evaluation index is used to evaluate the state of the characteristic parameters through a variable weight comprehensive evaluation model, and an index weight function is determined; The weight function calculates the initial weight values and the optimal order relationship of the importance evaluation indexes of each state parameter, and obtains each importance evaluation index value; the state of the feed water pump turbine is determined according to the importance evaluation index value; In response to the reliability state of the feed water pump turbine, a maintenance strategy is recommended by fusing thermal economic analysis.

[0023] Step 11, extraction of reliability characteristics of the feed water pump turbine, which includes key monitoring parameters such as the flow of the working medium, bearing temperature, lubricating oil pressure, oil return temperature, bearing vibration, rotating speed, axial displacement, and exhaust pressure.

[0024] Step 12, including extraction of characteristic quantities based on principal component analysis, which transforms the high-dimensional original characteristic space into a low-dimensional characteristic space to find out the most representative and effective characteristics.

[0025] Step 13, determination of state evaluation criteria and state threshold values.

[0026] Step 131, the setting of the state threshold value adopts the following method: 1) Fixed state threshold value; According to the standard values of each state, for example, the equipment vibration intensity is divided into 4 levels, which represent 4 states of the equipment respectively.

[0027] 2) Statistical state threshold value; The state threshold values of each level are determined by the following formula: ; In the formula, is the state threshold value of the i-th level, which can be determined according to the importance and use of the equipment.

[0028] ​Step 132, state evaluation of state characteristic parameters is performed using a variable weight comprehensive evaluation model to determine an index weight function.

[0029] Step 14, reliability evaluation, accurately evaluate the unit operation state to arrange the unit maintenance and maintenance strategy. For equipment state description, the processing method is given: Step 141, good state. It can continue to be used and is suitable for long-term operation.

[0030] Step 142, better state. The system shows abnormal signs, and can run for a period of time in this state before taking appropriate measures.

[0031] Processing method: strengthen monitoring.

[0032] Step 143, general state. The system shows more serious abnormal signs and is in a "sick running" state. Measures should be taken for maintenance or adjustment of operation mode.

[0033] Processing method: timely fault diagnosis, find fault source according to fault signs, and determine fault position to arrange maintenance in time.

[0034] Step 144, fault state. The system shows serious abnormal signs and cannot run for a long time, reaching the shutdown maintenance limit.

[0035] Processing method: check and repair as soon as possible.

[0036] Step 21, maintenance cost calculation; Step 211, labor cost (C1) calculation; ; Indicates the number of maintenance personnel (person); Indicates the maintenance time (hours); Indicates the labor rate (yuan / person·hour.

[0037] Step 212, spare parts and consumables cost (C2) calculation; ; Step 213, total maintenance cost: ; Step 22, maintenance benefit calculation.

[0038] When the feedwater system is running normally, with the running time, the cylinder efficiency of the feedwater pump turbine decreases, more steam is needed to drive the feedwater pump, which leads to the decrease of the main steam turbine power generation and the increase of the boiler coal consumption. If maintenance is implemented, the cylinder efficiency of the feedwater pump turbine is improved, the coal consumption is reduced, the power generation cost is reduced, and the maintenance benefit is brought. The change of power supply coal consumption is calculated by the equivalent enthalpy drop method to master the influence of the feedwater pump turbine cylinder on economy: Step 221; steam extraction equivalent enthalpy drop and steam extraction efficiency : ; .

[0039] represents the specific enthalpy of the main steam turbine new steam (kJ / kg), represents the specific entropy of the main steam turbine new steam (kJ / (kg·K)); represents the steam extraction point parameters; represents the condenser temperature.

[0040] Step 222; the influence of feed water pump efficiency improvement on steam consumption: The relationship between the power required by the feed water pump turbine to drive the feed water pump (kW) and steam consumption: , If the feed water pump turbine efficiency rises from to , the steam consumption is reduced to: , Step 223, because the feed water pump turbine efficiency rises, the coal consumption for power supply decreases, the coal consumption decreases from two parts, one part is the direct coal consumption decrease, which comes from the reduction of steam consumption, the amount of coal burned by the boiler decreases, the other part is the indirect coal consumption decrease, because the steam extraction amount recovers (reduces), increases a part of power generation.

[0041] Step 224, the direct coal consumption reduction amount , the heat corresponding to the reduced steam: ; converted into the coal consumption reduction amount (direct coal consumption reduction amount): ; Step 225, the indirect coal consumption reduction amount , the main steam turbine increases a part of power generation because of the reduction of steam extraction amount: ; Step 226, the reduced part of coal consumption of the increased power generation: ; represents the low calorific value of coal.

[0042] The total coal consumption reduction amount is: ; Step 227, maintenance benefit: ; represents the coal-in price; represents the operation time; represents the total power of the power plant.

[0043] Step 228, under the premise that the equipment is normal, from the perspective of thermal economy, if the maintenance benefit is less than the maintenance cost, the feed water pump turbine can continue to operate, and if the maintenance benefit increases to equal or greater than the maintenance cost with the increase of the operation time, the maintenance should be considered.

[0044] The application proposes a dynamic comprehensive evaluation method combining reliability and economic analysis framework, realizes scientific and quantitative evaluation of the equipment state by constructing a multi-dimensional evaluation index system. According to the actual operation of the equipment, the maintenance cycle of the feed water pump turbine is determined from the economic point of view on the premise that the reliability index does not decrease, human intervention is reduced, and a multi-dimensional dynamic interactive model is realized to realize holographic evaluation of the equipment state. At the reliability modeling level, a multi-physical field coupling model is proposed to realize state prediction under the synergistic action of multiple factors. At the same time, the economic analysis method is used to assist operation and maintenance from the perspective of maintenance cost and energy saving benefit, and the equipment state parameters are converted into economic indicators in real time. When the equipment is running normally and the reliability has not decreased obviously, the preliminary economic index basis is provided for the decision maker.

[0045] Compared with the traditional periodic maintenance or passive maintenance method, the method provides a feed water pump turbine reliability state priority method on the one hand, and provides an economic auxiliary decision-making idea on the basis of normal equipment index and stable operation on the other hand. This technical path not only prolongs the service value of the equipment, but also reduces the economic loss caused by unplanned shutdown.

[0046] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the technical field, several improvements and modifications can be made without departing from the technical principles of the application, and these improvements and modifications should also be considered as the protection scope of the application.

Claims

1. A method for evaluating a state of a feed water pump turbine of a thermal power plant, characterized by, The method comprises: extracting the characteristic parameters of the steam flow, bearing metal temperature, lubricating oil pressure, oil return temperature, bearing vibration, rotating speed, axial displacement and exhaust pressure of the feed water pump turbine; transforming the high-dimensional original characteristic space into a low-dimensional characteristic space to find out representative and effective characteristic quantities; the characteristic quantities use the degradation degree of the state threshold value as the evaluation index of the operating state; the evaluation index performs state evaluation on the state characteristic parameters through a variable weight comprehensive evaluation model to determine the index weight function; the weight function calculates the various initial weight values and optimal order relations of the importance evaluation indexes of the state parameters to obtain the importance evaluation index values; and determines the state of the feed water pump turbine according to the importance evaluation index values; in response to the reliability state of the feed water pump turbine, a maintenance strategy is recommended by combining with thermal economic analysis.

2. The method of claim 1, wherein the method is characterized by: The state evaluation index comprises a fixed state threshold value and a statistical state threshold value; the fixed state threshold value is obtained by comparing the values representing the state of the equipment measured at the same position of the feed water pump turbine or according to certain requirements with a certain corresponding judgment standard value to evaluate the operating state; The statistical state threshold formula determines a state threshold, calculating a mean value of the monitoring parameter and a standard deviation : ； In the formula: is the state threshold of the determined according to the importance and use of the device.

3. The method of claim 1, wherein the method is characterized by: the state of the feed water pump turbine comprises a good state, a better state, a general state and a fault state, wherein: the good state means that the feed water pump turbine can continue to be used and is suitable for long-term operation; the better state means that the feed water pump turbine has abnormal signs and can be operated for a period of time before the appropriate maintenance time; the general state means that the feed water pump turbine has relatively serious abnormal signs and should be repaired or adjusted in operation mode; the fault state means that the feed water pump turbine has serious abnormal signs and cannot be operated for a long time, reaching the shutdown maintenance limit.

4. The method of claim 1, wherein the method is characterized by: The thermal economic analysis comprises maintenance cost and maintenance benefit, and the maintenance cost comprises: labor cost (C1): ； represents the number of maintenance personnel, units are pieces; represents the time spent on the repair, in hours; represents the labor rate, in yuan per person-hour; the maintenance cost calculation comprises spare parts and consumable cost (C2): ； represents the spare parts quantity, unit: pieces; represents the spare part unit price, in yuan per unit; The overhaul cost is: .

5. The method of claim 4, wherein the method is characterized by: the maintenance benefit comprises the thermal economic benefit caused by the efficiency change of the feed water pump turbine through maintenance; and the thermal economic benefit comprises the fuel cost reduction of the direct coal consumption reduction and the indirect coal consumption reduction.

6. The method of claim 5, wherein the method is characterized by: The direct coal consumption reduction amount is due to the fact that the steam consumption required by the feed water pump turbine is reduced by improving the operation efficiency through the maintenance activities, the steam consumption reduction leads to the coal consumption reduction, and thus the cost saving amount is generated; Direct steam consumption, by: extraction equivalent enthalpy drop and extraction efficiency : ； ； Hs represents the specific enthalpy of the new steam of the main steam turbine and Hs represents the specific entropy of the new steam of the main steam turbine; represents the extraction point parameters; represents the condenser temperature; The power required to drive the feedwater pump by the feedwater pump steam turbine Relationship with the steam consumption: ； If the feed water pump turbine efficiency is raised from to , the steam consumption is reduced by: ； thermal change corresponding to steam: ； direct coal consumption reduction: 。 7. The method of claim 6, wherein the method is characterized by: The indirect coal consumption reduction amount Is the indirect coal consumption cost saving generated by the main steam turbine power generation increase caused by the feed water pump turbine efficiency improvement.

8. The method of claim 7, wherein the method is characterized by: the indirect coal consumption comprises: the part of the increased power due to the reduction of the steam extraction amount of the main turbine: ； the part of the reduced power consumption, the indirect coal consumption reduction: ； represents the low calorific value of the coal.

9. The method of claim 8, wherein the method is characterized by: the total coal consumption reduction of the direct coal consumption and the indirect coal consumption is: 。 10. The method of claim 9, wherein the method is characterized by: the fuel cost reduction of the direct coal consumption reduction and the indirect coal consumption reduction is the maintenance benefit. ； represents the price of coal in at the plant; represents the operating time; represents the total power of the plant.

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