An optimization method, system and device for cold and warm state start of a unit

Abstract

The application discloses a kind of optimization method, system and device of unit cold, warm state start, belong to generator unit technical field, to solve the technical problems of long time consumption, water consumption and large steam drum wall temperature difference in boiler temperature rising and pressure rising process in cold state and warm state start in prior art, research unit cold state, warm state start process, optimize cold state, warm state start process, shorten unit start time consumption, reduce boiler flushing water consumption, control steam drum wall temperature difference can reduce unnecessary energy consumption, according to the characteristics of unit cold state and warm state start, make the scheme of optimizing waste heat boiler cold state flushing, optimizing steam turbine cold state start and optimizing waste heat boiler steam drum wall temperature difference control, in preparation stage, use auxiliary steam to heat steam turbine cylinder temperature to near 220 DEG C-240 DEG C, low pressure system, medium pressure system and high pressure system are washed by using water, high pressure steam drum water is heated to 90 DEG C-120 DEG C, effectively shorten the time consumption of boiler flushing and unit start, and the steam drum wall temperature difference is effectively controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of generator set, in particular to a method, system and device for optimizing cold and warm state start of a generator set. BACKGROUND

[0002] A gas-steam combined cycle generator set is a circulating system composed of a gas turbine, a generator, a waste heat boiler and a steam turbine. It is a combined system in which high-temperature exhaust flue gas discharged after the gas turbine generates power is recovered and converted into steam by the waste heat boiler, and the steam is sent to the steam turbine to generate power. Common forms include single-shaft combined cycle in which the gas turbine and the steam turbine drive a generator coaxially, and multi-shaft combined cycle in which the gas turbine and the steam turbine are combined with a generator respectively. The gas-steam combined cycle generator set has the advantages of high thermal efficiency, clean and environmentally friendly, and rapid start and stop.

[0003] The start state of the gas-steam combined cycle generator set is generally divided into cold state, warm state and hot state according to the metal temperature of the steam turbine (at the high-pressure inlet). The start state determines the temperature rise rate and the time consumption of the start of the generator set. The time consumption of the cold state start is the longest, and the time consumption of the hot state start is the shortest. When the steam turbine enters the warm state, the waste heat boiler has been drained and the metal temperature has approached room temperature. Before the cold state start or the warm state start of the generator set, the boiler needs to be refilled with water. In order to ensure the quality of the steam turbine inlet, the boiler needs to be supplemented and flushed during the water filling process until the indicators are qualified. This process consumes a large amount of desalted water. Compared with the hot state start, the cylinder temperature of the steam turbine during the cold state start and the warm state start is much lower than the rated inlet temperature. The start process is a process of warming up the steam turbine and expanding the cylinder. The thick cylinder determines that this process cannot be too fast. In addition to the long time consumption and water consumption of the cold state start and the warm state start, there is also a large temperature difference between the upper and lower walls of the steam drum during the boiler temperature and pressure rising process, which threatens the safe operation of the steam drum. SUMMARY

[0004] The present application aims to study the cold state and warm state start process of the generator set, optimize the cold state and warm state start process, shorten the time consumption of the start of the generator set, reduce the water consumption of the boiler flushing, control the wall temperature difference of the steam drum, reduce unnecessary energy consumption, improve the reliability of the equipment, and improve the safety and economy of the power plant.

[0005] A method for optimizing the cold and warm state start of a generator set, in which the temperature of the steam turbine cylinder and the steam valve is heated before starting, and the high-pressure steam drum water is heated after the boiler is filled with water.

[0006] Specifically, in the preparation stage, the temperature of the steam turbine cylinder is heated to 220-240℃ by using auxiliary steam, and the high-pressure steam drum water is heated to 90-120℃ by using auxiliary steam.

[0007] Specifically, the following specific steps are included:

[0008] S1: start the waste heat boiler cold flushing;

[0009] S11: the condenser hot well water is flushed into the low-pressure system after flushing the condensate water pipeline at a small flow rate, and under the condition of condensate water cooling, the warm pipe operation of the auxiliary steam system is started, and the heat generated by the warm pipe is brought into the waste heat boiler by the condensate water;

[0010] S12: after the low-pressure system sees the water level, start the variable flow flushing, and assist the steam into the low-pressure system deaerator head, and raise the feedwater temperature of the high-pressure system and the medium-pressure system to 45-65℃;

[0011] S2: open the cold start of the steam turbine;

[0012] S21: in the start-up preparation stage, use auxiliary steam to heat the steam turbine cylinder temperature to 220-240℃;

[0013] S22: proceed according to the warm start-up program, and forcibly open the main steam regulating valve to heat the high-pressure system valve body;

[0014] S3: control the wall temperature difference of the waste heat boiler drum;

[0015] S31: after the boiler is filled with water, use auxiliary steam to heat the high-pressure drum water to 90-120℃, and then after the gas turbine is ignited, maintain the bypass valve opening degree to 80% to suppress the high-pressure drum pressure rise rate;

[0016] S32: during the boiler temperature and pressure rise stage, when the economizer outlet water temperature is higher than the lower wall temperature of the drum, open the fixed exhaust and increase the drum water replacement.

[0017] Specifically, in the step S1, the low-pressure system, the medium-pressure system and the high-pressure system all adopt the water level flushing mode, and after the second high water level, the boiler water reaches the qualified standard, and then is heated at the bottom of the high-pressure drum.

[0018] Specifically, in the step S22, the heated auxiliary steam valve body is fully utilized for heating, so that the temperature difference of each metal during the start-up process is controlled at the warm start-up level.

[0019] Specifically, in the step S3, during the boiler temperature and pressure rise stage, the drum water level is controlled at a low position to suppress the temperature rise rate of the upper wall of the drum.

[0020] An optimization system for cold and warm state of a gas-steam combined cycle unit, comprising:

[0021] A waste heat boiler cold state flushing module is used for flushing the condensate water pipeline with the condenser hot well water at a small flow rate, and then flushing into the low pressure system, and when the low pressure system sees the water level, the variable flow flushing is started, and the steam is introduced into the low pressure system deoxidization head to assist in deoxidization;

[0022] A steam turbine cold state starting optimization module is used for heating the steam turbine cylinder temperature to 220-240 DEG C by using auxiliary steam in the starting preparation stage, and forcibly opening the main steam regulating valve to heat the high pressure system valve body;

[0023] A waste heat boiler drum wall temperature difference control module is used for heating the high pressure drum water to 90-120 DEG C by using auxiliary steam after the boiler is filled with water, and inhibiting the high pressure drum pressure rising rate.

[0024] A kind of gas-steam combined cycle unit cold, warm state optimization device, including processor, the processor contains computer executable program, the program can realize the optimization method of the unit cold, hot state starting.

[0025] The beneficial effects of the present application are: according to the characteristics of the unit cold state and warm state starting, the schemes of optimizing the waste heat boiler cold state flushing, optimizing the steam turbine cold state starting and optimizing the waste heat boiler drum wall temperature difference control are formulated, the steam turbine cylinder temperature is heated to near 220-240 DEG C by using auxiliary steam in the preparation stage, the low, medium and high pressure systems are flushed by using the water, the high pressure drum water is heated to 90-120 DEG C, the high pressure drum pressure rising rate is inhibited after the gas turbine is ignited, when the coal economizer outlet water temperature is higher than the drum lower wall temperature, the fixed discharge is opened, the drum water replacement is increased and other measures, the time consumption of the boiler flushing and the unit starting is effectively shortened, the drum wall temperature difference is effectively controlled, unnecessary energy consumption is reduced, the equipment reliability is improved, and the safety and economy of the power plant are improved. Embodiment

[0026] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described.

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application, that is, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments, and all the features disclosed in the specification or the steps in all the disclosed methods can be combined in any way, except that the features and / or steps are mutually exclusive.

[0028] Therefore, the following detailed description of embodiments of the application is not intended to limit the scope of the application as claimed, but merely to represent selected embodiments of the application. Based upon the embodiments of the application, all other embodiments obtained by persons of ordinary skill in the art without departing from the inventive concept are within the scope of the application.

[0029] It should be noted that the relational terms herein, such as first and second, and the like, are used solely to distinguish one from another entity or action, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0030] Case 1: An optimization method for unit cold and warm state start, in the preparation stage, the steam turbine cylinder temperature is heated to 220℃ by using auxiliary steam, and the high-pressure drum water is heated to 95℃ by using auxiliary steam heating, comprising the following specific steps:

[0031] S1: Start the cold flushing of the waste heat boiler;

[0032] S11: The condenser hot well water flushes the condensate pipeline at a small flow rate and then enters the low-pressure system for flushing. In the case of condensate cooling, the warm-up operation of the auxiliary steam system is started, and the heat generated by the warm-up operation is just taken away by the condensate into the waste heat boiler;

[0033] S12: After the low-pressure system sees the water level, variable flow flushing is started, and auxiliary steam is introduced into the low-pressure system deaerator head to raise the high and medium pressure system feedwater temperature to 45℃;

[0034] The original cold flushing method requires the cooperation of laboratory personnel, and the main indicators of cold flushing are pH and iron. The measurement of iron in water requires nearly 30 minutes to obtain the results. Therefore, before optimization, the cold flushing of the waste heat boiler takes more than 14 hours, consumes 1400 tons of water, and requires laboratory personnel to participate in shift work, which is labor-intensive and costly.

[0035] After adopting the new flushing method, in the current power market operating environment, the waste heat boiler cold flushing process does not require laboratory personnel to be on duty continuously, but only needs to be tested and left behind when the start-up preparation is completed, reducing unnecessary labor costs.

[0036] S2: open the steam turbine cold start;

[0037] S21: in the preparation stage, the steam turbine cylinder temperature is heated to 220℃ by auxiliary steam;

[0038] S22: according to the warm state starting procedure, the main steam regulating valve is forced to open to heat the high pressure system valve body;

[0039] S3: control the wall temperature difference of the waste heat boiler drum;

[0040] S31: after the boiler is filled with water, the high pressure drum water is heated to 95℃ by auxiliary steam, and then the gas turbine is ignited, and the bypass valve opening is maintained at 80% to inhibit the high pressure drum pressure rise rate,

[0041] S32: in the boiler heating and pressure rising stage, when the economizer outlet water temperature is higher than the lower wall temperature of the drum, the fixed exhaust is opened, and the drum water exchange is increased.

[0042] Case two: an optimization method for cold and warm state starting of a unit, in the preparation stage, the steam turbine cylinder temperature is heated to 230℃ by auxiliary steam, and the high pressure drum water is heated to 110℃ by auxiliary steam heating, comprising the following specific steps:

[0043] S1: start the cold flushing of the waste heat boiler;

[0044] S11: the condenser hot well water flushes the condensate pipeline at a small flow rate, and then enters the low pressure system for flushing, and in the presence of condensate cooling, the warm pipe operation of the auxiliary steam system is started, and the heat generated by the warm pipe is just taken away by the condensate into the waste heat boiler;

[0045] S12: after the low pressure system sees the water level, variable flow flushing is started, and auxiliary steam is introduced into the low pressure system deaerator to raise the high and medium pressure system feedwater temperature to 50℃;

[0046] The original cold flushing method requires the cooperation of laboratory personnel, and the main indicators of cold flushing are pH and iron, and the measurement of iron in water needs to wait for nearly 30 minutes to get the result. Therefore, before optimization, the waste heat boiler cold flushing time is as long as 14 hours or more, the water consumption is 1400 tons, and the laboratory personnel need to participate in shift work during the flushing process, which is laborious and costly;

[0047] After adopting the new flushing method, in the current power market operating environment, the waste heat boiler cold flushing process does not require laboratory personnel to continuously work, and only needs to be tested and left at the completion of the starting preparation, reducing unnecessary labor costs.

[0048] S2: open the steam turbine cold start;

[0049] S21: In the start preparation stage, the steam turbine cylinder temperature is heated to 230℃ by auxiliary steam;

[0050] S22: The warm state start procedure is performed, and the main steam regulating valve is forcibly opened to heat the high pressure system valve body;

[0051] S3: Control the waste heat boiler drum wall temperature difference;

[0052] S31: After the boiler is filled with water, the high pressure drum water is heated to 110℃ by auxiliary steam, and then the gas turbine is ignited, and the bypass valve opening is maintained at 80% to inhibit the high pressure drum pressure rise rate,

[0053] S32: In the boiler temperature and pressure rise stage, when the economizer outlet water temperature is higher than the lower wall temperature of the drum, the fixed exhaust is opened, and the drum water replacement is increased.

[0054] The improved waste heat boiler cold flushing time is shortened from the original 14 hours to 6 hours, and the flushing water consumption is reduced from the original 1400t to 800t; The cold start time of more than 14 days is shortened from the original 7 hours to 4.5 hours, and the unit start-up cost is reduced by about 120,000 yuan each time, and the upper and lower wall temperature difference of the drum is basically controlled within 40℃.

[0055] Case three: The existing steam turbine high pressure cylinder metal is thick, and the temperature of the steam turbine high pressure inlet is low before starting, and the unit start-up time is long.

[0056] To solve the problem of long time of steam turbine high pressure cylinder cold start, the optimization method is proposed: before starting the steam turbine high pressure cylinder, the condenser maintains a high vacuum state, the high pressure main regulating valve is opened to 20%, the high pressure exhaust check valve is closed, the auxiliary steam enters from the steam turbine high pressure cylinder outlet, and is discharged from the steam turbine high pressure cylinder inlet, and then is discharged into the condenser after passing through the high pressure main regulating valve and the high pressure main steam valve and the drain valve.

[0057] In the case that the temperature of the steam turbine high pressure inlet is close to room temperature, the auxiliary steam is continuously introduced to heat the high pressure cylinder and the high pressure main regulating valve in reverse flow, which can increase the temperature of the steam turbine high pressure inlet by 17 to 245℃ -65℃, realize the preheating of the steam turbine high pressure cylinder before starting, and change the starting state of the steam turbine high pressure cylinder from the original cold state to the warm state, greatly shorten the starting time of the steam turbine high pressure cylinder and the steam turbine middle and low pressure cylinder.

[0058] Case four: Steam turbine in cold state needs to use steam to heat the cylinder and valve, so it needs nearly 7 hours of start-up time, by using auxiliary steam in the preparation stage to heat the steam turbine cylinder temperature to nearly 220-240 ℃, the cylinder temperature is nearly 80 ℃ higher than the standard temperature of cold start, in the process of starting, the warm-up process of the steam engine is omitted, and the time of the fixed speed is shortened by about 35 minutes. At the same time, the initial cylinder expansion ratio is nearly 9 mm larger than that of cold start, which greatly shortens the warm-up waiting time after the steam turbine is connected to the grid. In addition, by forcibly opening the main steam regulating valve, the high-pressure system valve body is heated, and the heated auxiliary steam is fully utilized to control the temperature difference of each metal in the starting process at the warm start level.

[0059] After adopting the new starting method, the unit "avoids cold start", the process of starting less thermal shock to the metal, greatly prolongs the service life of the unit, and improves the reliability of the equipment. At the same time, the starting time of the unit is shortened from 7 hours to 4.5 hours, and the starting cost can be reduced by about 120,000 yuan each time.

[0060] Case five: When the unit is started in cold state, the high-temperature flue gas discharged by the gas turbine enters the waste heat boiler after the gas turbine is started and ignited. As the pressure of the steam drum of the waste heat boiler rises, the temperature of the boiler water and steam also rises. The lower half of the steam drum is heated by the boiler water, and the upper half is heated by the steam. Because the heat release coefficient of steam condensation is much larger than that of boiler water, in the process of pressure rise, the wall temperature of the upper half of the steam drum is higher than that of the lower half. Thus, a temperature difference is formed between the upper and lower walls of the steam drum. In the past, during the cold and warm start process of the unit, the wall temperature difference of the steam drum was close to 90-120 ℃.

[0061] In view of the above phenomenon, the following control measures are developed through continuous exploration. First, after the boiler is filled with water, the auxiliary steam is used to heat the high-pressure steam drum water to about 90-120 ℃, and then the bypass valve is opened to 80% to suppress the pressure rise rate of the high-pressure steam drum after the gas turbine is ignited. In addition, during the boiler temperature and pressure rise stage, when the outlet water temperature of the economizer is higher than the lower wall temperature of the steam drum, the fixed exhaust is opened to increase the water exchange of the steam drum. During the boiler temperature and pressure rise stage, the water level of the steam drum is controlled at a low level.

[0062] After adopting the above control measures, the rising rate of the upper wall temperature of the steam drum is suppressed, the rising rate of the lower wall temperature of the steam drum is improved, and the wall temperature difference of the steam drum is effectively controlled. During the cold and warm start of the unit, the temperature difference between the upper and lower walls of the steam drum is basically controlled within 40 ℃, which greatly improves the safety of the steam drum operation.

[0063] In the above step S22, the heated auxiliary steam valve body is fully utilized for heating, so that the temperature difference of each metal in the starting process is controlled at the warm start level.

[0064] Case seven: a gas-steam combined cycle unit cold and warm state optimization system, comprising:

[0065] A waste heat boiler cold flushing module is used to flush the condenser hot well water into the low-pressure system after flushing the condensate water pipeline at a small flow rate, and when the low-pressure system reaches the water level, start the variable flow flushing and assist the steam into the low-pressure system deaerator head;

[0066] A steam turbine cold start optimization module is used to heat the steam turbine cylinder temperature to 220-240 DEG C using auxiliary steam during the start preparation stage, and forcibly open the main steam regulating valve to heat the high-pressure system valve body;

[0067] A waste heat boiler drum wall temperature difference control module is used to heat the high-pressure drum water to 90-120 DEG C using auxiliary steam after the boiler is filled with water, and to inhibit the high-pressure drum pressure rise rate.

[0068] A gas-steam combined cycle unit cold and warm state optimization device, comprising a processor, the processor contains a computer executable program, the program can realize the optimization method of the unit cold and hot state start, comprising the following specific steps: S1: starting the waste heat boiler cold flushing;

[0069] S11: the condenser hot well water flushes the condensate water pipeline at a small flow rate and then enters the low-pressure system for flushing, and under the condition of condensate water cooling, the warm pipe operation of the auxiliary steam system is started, the heat generated by the warm pipe is just brought into the waste heat boiler by the condensate water;

[0070] S12: after the low-pressure system reaches the water level, start the variable flow flushing, and assist the steam into the low-pressure system deaerator head, and raise the high and medium pressure system feed water temperature to 45-65 DEG C;

[0071] S2: open the steam turbine cold start;

[0072] S21: in the start preparation stage, the steam turbine cylinder temperature is heated to 220-240 DEG C using auxiliary steam;

[0073] S22: according to the warm state start program, and forcibly open the main steam regulating valve to heat the high-pressure system valve body;

[0074] S3: control the waste heat boiler drum wall temperature difference;

[0075] S31: after the boiler is filled with water, the high-pressure drum water is heated to 90-120 DEG C using auxiliary steam, and then the gas turbine is ignited, and the high-pressure drum pressure rise rate is inhibited by maintaining the bypass valve opening degree to 80%,

[0076] S32: in the boiler temperature and pressure stage, when the economizer outlet water temperature is higher than the down wall temperature of the steam drum, open the fixed row and increase the steam drum water exchange.

[0077] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. An optimization method for cold and warm state start of a unit, characterized in that, The temperature of the steam turbine cylinder and valve is heated before starting, and the high-pressure drum water is heated after the boiler is filled with water; The method comprises the following specific steps: S1: starting the cold flushing of the waste heat boiler; S11: the condenser hot well water is flushed into the low-pressure system after flushing the condensate water pipeline at a small flow rate, and in the case of condensate water cooling, the warm pipe operation of the auxiliary steam system is started, and the heat generated by the warm pipe is brought into the waste heat boiler by the condensate water; S12: after the low-pressure system reaches the water level, variable flow flushing is started, and the auxiliary steam is introduced into the deaerating head of the low-pressure system; the feedwater temperature of the high-pressure system and the medium-pressure system is raised to 45-65 DEG C; S2: opening the cold starting of the steam turbine; S21: in the starting preparation stage, the temperature of the steam turbine cylinder is heated to 220-240 DEG C by using the auxiliary steam; S22: the warm starting procedure is performed, and the main steam regulating valve is forcibly opened to heat the valve body of the high-pressure system; S3: controlling the wall temperature difference of the waste heat boiler drum; S31: after the boiler is filled with water, the high-pressure drum water is heated to 90-120 DEG C by using the auxiliary steam, and then the gas turbine is ignited, and the bypass valve opening is maintained at 80% to inhibit the pressure rising rate of the high-pressure drum; S32: in the boiler temperature and pressure rising stage, when the water temperature at the outlet of the economizer is higher than the lower wall temperature of the drum, the fixed exhaust is opened, and the water exchange of the drum is increased; In the step S1, the low-pressure system, the medium-pressure system and the high-pressure system all adopt the water level flushing mode, and after reaching the second high water level, the boiler water reaches the qualified standard, and then is heated at the bottom of the high-pressure drum; In the step S22, the valve body of the high-pressure system is heated by forcibly opening the main steam regulating valve, and the auxiliary steam is fully utilized to control the temperature difference of each metal in the starting process within the warm starting level.

2. The method of claim 1, wherein, In the preparation stage, the temperature of the steam turbine cylinder is heated to 220-240 DEG C by using the auxiliary steam, and the high-pressure drum water is heated to 90-120 DEG C by using the auxiliary steam heating.

3. The method of claim 1, wherein, In the step S3, in the boiler temperature and pressure rising stage, the drum water level is controlled at a low position to inhibit the temperature rising rate of the upper wall of the drum.

4. A system for optimizing the cold and warm state of a gas and steam combined cycle unit for implementing the method for optimizing the start-up of the cold and warm state of the unit according to any one of claims 1 to 3, characterized in that, It comprises: a waste heat boiler cold flushing module for flushing the condenser hot well water into the low-pressure system after flushing the condensate water pipeline at a small flow rate, starting variable flow flushing when the low-pressure system reaches the water level, and introducing the auxiliary steam into the deaerating head of the low-pressure system; a steam turbine cold starting optimization module for heating the temperature of the steam turbine cylinder to 220-240 DEG C by using the auxiliary steam in the starting preparation stage, and forcibly opening the main steam regulating valve to heat the valve body of the high-pressure system; a waste heat boiler drum wall temperature difference control module for heating the high-pressure drum water to 90-120 DEG C by using the auxiliary steam after the boiler is filled with water, and inhibiting the pressure rising rate of the high-pressure drum.

5. A device for optimizing cold and warm state of a gas-steam combined cycle unit, comprising a processor, wherein the processor contains a computer executable program, and the computer executable program comprises the following steps of: receiving a cold and warm state optimization request; determining a cold and warm state optimization scheme according to the cold and warm state optimization request; and sending the cold and warm state optimization scheme to a user. The program can realize the optimization method of the cold and warm starting of the unit as claimed in any one of claims 1-3.