CN210088824U - Self-adaptive adjusting device for end difference of heater of thermal power generating unit - Google Patents
Self-adaptive adjusting device for end difference of heater of thermal power generating unit Download PDFInfo
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- CN210088824U CN210088824U CN201920700645.4U CN201920700645U CN210088824U CN 210088824 U CN210088824 U CN 210088824U CN 201920700645 U CN201920700645 U CN 201920700645U CN 210088824 U CN210088824 U CN 210088824U
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Abstract
The utility model discloses a thermal power unit heater end difference self-adaptation adjusting device, this adjusting device includes temperature measurement module one, pressure measurement module, temperature measurement module two, temperature measurement module three, water level measurement module, controller and heater drainage regulating valve, temperature measurement module one, pressure measurement module, temperature measurement module two, temperature measurement module three and water level measurement module all are connected with the signal receiving terminal electricity of controller, the control end and the heater drainage regulating valve electricity of controller are connected, the human-computer interaction end and the touch screen electricity of controller are connected. The utility model discloses can gather high pressure feed water heater upper and lower end difference, introduce the end difference and control high pressure feed water heater water level regulation, realize the unit at the automatically regulated of wide load within range heater end difference, adjust more accurately.
Description
Technical Field
The utility model belongs to the technical field of thermal power, a can be according to the unit at different load operating modes, carry out heater end difference adjusting method and device automatically.
Background
One of the important guidelines of the energy development strategy in China is to improve the energy utilization efficiency. In a thermal power generation system, how to improve the unit economy is always an important content in the energy saving and consumption reduction work of each thermal power generation enterprise.
The regenerative steam extraction heating is one of measures for improving the efficiency of a power plant, the regenerative steam extraction system is a main component of a principle thermodynamic system of a thermodynamic generator set, a steam turbine is used for heating feed water entering a boiler by using steam with partial work, the steam does not release heat to cooling water in a condenser any more, the heat of the steam is prevented from being taken away by circulating cooling water, the heat of the steam is fully utilized, meanwhile, the steam turbine is used for heating the feed water by using the steam with partial work, the feed water temperature is improved, the heat transfer temperature difference of a heating surface of the boiler is reduced, the irreversible loss in the feed water heating process is reduced, the heat absorption capacity in the boiler is correspondingly reduced, and the cycle efficiency of the unit is improved. The regenerative cycle is a heating system consisting of a regenerative heater, a regenerative steam extraction pipeline, a water pipeline, a drainage pipeline and the like, and the regenerative heater is the core of the system. A typical regenerative system of a large thermal generator set is shown in figure 1.
End difference concept: except that the deaerator belongs to a mixed heater in a regenerative system, other heaters all adopt surface heaters, most heaters (particularly high-pressure heaters) adopt three-section arrangement, namely a superheated steam cooling section, a steam condensation section and a drainage cooling section, and the end difference of the surface heater of the type exists in the concept of upper and lower end difference, namely the upper end difference of the heater generally refers to the difference between the saturation temperature under the steam extraction pressure of the heater and the water temperature at the outlet of the heater; the difference of the lower ends is the difference between the drainage temperature of the heater and the inlet water temperature of the heater.
The water level of the high-pressure heater has influence on the unit: in the aspect of unit operation safety, when the water level is too low, steam-water two-phase flow can be formed in the heater and the drainage pipeline, so that the pipe wall of the heater is washed to cause pipe bundle vibration and erosion, and meanwhile, the valve core of the drainage regulating valve is eroded to influence the precision of the regulating valve. If the water level is too high, the heater is disconnected if the water level is too high, the economic efficiency of the unit is influenced, and if the water level is too high, the water enters the steam turbine, and the safety of the unit is seriously influenced. For the aspects of the heater end difference and the unit economy, a three-section type heater variable working condition mathematical model is established in the literature of 'analysis of influence of water level change of a high-pressure feed water heater on the unit economy' (Naxu light; 'mechanical Engineer; year 2012, No. 07)', and the influence of the water level of the heater on the end difference under different loads is calculated by taking a No. 1 high-pressure heater of a certain 330MW unit as an example. According to the introduction of a high-pressure heater water level control and protection system in the literature (Jing Changcai, Zhang Wei, Liu Si Hai; power station auxiliary machinery, No. 2013, No.) ", theoretical calculation and field test show that the high-pressure heater water level is too high or too low, and certain influence is generated on the economy and safety of a unit. The literature "method for determining the optimal operating water level of a high-pressure heater (pomle, guo-jia-lei, Bing hankun;" power generation and air conditioning; "2014 03.)" shows that under a certain load of a unit, the heater may increase the end difference due to improper water level control, so that the heat transfer condition is deteriorated.
The influence of the end difference of the heater on the thermal generator set is as follows: specifically, the method comprises the following steps: (1) the larger the upper end difference is, the feed water is not sufficiently heated by the superheated steam of the heater, namely the steam extraction heating capacity of the current stage is not enough, so that the heating task of the current stage heater is phase-changed and is unloaded to the next stage heater, the steam extraction quantity of the next stage heater is increased, namely the low-quality steam extraction of the current stage is expelled, and the high-quality steam extraction quantity of the next stage is increased. (2) The lower end difference is too large, which indicates that the drainage of the heater is not fully cooled, the steam extraction capacity of the heater of the current stage is not fully exerted, and then the steam is discharged to the heater of the next stage, the low-quality steam extraction of the heater of the next stage is eliminated, the high-quality steam extraction quantity of the current stage is increased, and the efficiency is reduced. From the above qualitative analysis, in the aspect of economy, too large or too small of the heater end difference is not beneficial to the improvement of the cycle efficiency of the unit, and domestic scholars perform a lot of quantitative analysis on the influence of the heater end difference on the economy of the thermal power unit, for example, the influence of the ultra-supercritical unit heater end difference on the coal consumption rate (Tiankung, Zhang Peijing, Wang Huixing, rural bathing snow; turbine technology; 2012, 05 th) is analyzed to obtain that after each heater is adjusted to the optimal water level (the end difference is proper) through quantitative calculation on the low water level of a certain 600MW unit in China, the heat consumption of the unit is reduced by 5 kJ/kW.h; coal consumption is 0.2 g/kW.h; and 467.4t of annual coal. In the literature, "computational analysis of the end difference characteristics of feed water heaters under different operating conditions (Yanghai, Chengweigang; steam turbine technology; 04 year 2012)" takes a 1000MW ultra-supercritical unit as an example, a physical model of the influence of the end difference on a regenerative system is established, and the end difference of each heater is calculated to be increased by 2 ℃, and the coal consumption of the unit is increased by 0.7 g/kW.h. In the literature, "analysis of the influence of the end difference of a 1000MW secondary reheating unit heater on economy" (julian, songhuanfu, chenfeng, korean wei; "turbine technology"; 2016 (year 06) ") takes an imported 660MW unit as an example, the calculated values of the upper end difference and the lower end difference of a 7 # high-pressure heater are obtained under different loads, and the difference between the calculated values and the designed values is analyzed. The document' 600MW supercritical thermal power generating unit high and low pressure heater end difference optimization energy-saving analysis (Huwen is strong, 2015 is a collection of the theory of the conversion between the current situation of thermal power generation energy-saving modification and the development trend technology, 2015) takes a certain 1000MW supercritical secondary reheating unit regenerative heating system as a research object, and based on an equivalent enthalpy drop analysis method, the influence of the end difference of the heater on the unit economy in actual operation compared with the design value under the rated loads of 100%, 75% and 50% of the unit is calculated respectively. The calculation result shows that the end difference of the low-pressure heaters 1, 2 and 3 has great influence on the economic performance of the unit, and the additional loss is increased along with the reduction of the load. The document 'optimized operation of water level of a water supply heater of a power station (Yan, xu, Jue, and the like; university of southeast and east university's school newspaper (Nature science edition), 11 months 2012) obtains the relation between the water level and the end difference of a high-pressure heater and the load of a unit through tests, and shows that the water level of the heater needs to be increased to ensure that the end difference of the heater is at a designed value when the unit is under low load, and the water level of the heater needs to be properly reduced when the unit is.
The problems existing at present are as follows: (1) the main control indexes of the high-pressure heaters of most thermal power generating sets are water supply end difference (upper end difference) and water drainage end difference (lower end difference), thermal performance characteristic parameters provided by steam turbine manufacturers are designed to be fixed values at the upper end difference and the lower end difference of the heaters under different load working conditions. After the load is changed, parameters such as the water supply flow rate, the water inlet temperature, the steam extraction pressure, the steam extraction enthalpy value, the upper drainage inlet flow rate, the enthalpy value and the like of the high-pressure heater may deviate from the designed values more, so the original design end difference is not necessarily the best in a wide load range of a unit. (2) The most direct and effective method for adjusting the end difference of the heater is to control the water level of the heater by controlling the water level of the heater, so that the operation is simplified or the management is convenient, and most power plants adopt the same fixed water level value to control the water level of the heater under different load working conditions of the unit. The experiment of the following table 'operation parameters of a 660MW unit under the typical working conditions of high-pressure and deaerator' shows that the shadow of the water level to the end difference under different loads
Operating parameters of 660MW unit under typical working conditions of high-pressure heater and deaerator
The sound is different, and the high-pressure heater can not operate in the optimal state by adopting the same water level value to control the heater end difference in each load stage, so that the economic efficiency of a unit is influenced. (3) The upper end difference is the difference between the saturation temperature of the heater corresponding to the extraction pressure and the outlet water temperature. Usually, to obtain the saturation temperature, off-line table lookup or calculation by using special software is required, which affects the intuitive judgment of the operator on the performance index of the heater. (4) According to the peak regulation characteristic of a power system in China, most thermal power generating units basically operate in a 50% -100% rated load range, the difference of heater ends needs to be controlled to be an optimal value at different load stages, the water level of a heater needs to be adjusted in real time, the manual operation intensity is high, the precision is poor, and if the operation is careless, the high voltage system disconnection can be caused, and the safe operation of the units is influenced.
Disclosure of Invention
The to-be-solved technical problem of the utility model is: the self-adaptive adjusting device for the end difference of the heater of the thermal power generating unit is provided to solve the problem that the heater cannot operate in the optimal state due to the fact that the heater is controlled by using the same design end difference value or fixed water level after the load of most thermal power generating units is changed in the prior art; meanwhile, the problems that the difference between the upper end and the lower end of the heater is inconvenient to calculate, the labor intensity of operators is high, and the precision is poor are solved.
The utility model discloses the technical scheme who takes does: a self-adaptive adjusting device for the end difference of a heater of a thermal power generating unit comprises a first temperature measuring module, a first pressure measuring module, a second temperature measuring module, a third water level measuring module, a controller and a drain regulating valve of the heater, wherein the first temperature measuring module, the first pressure measuring module, the second temperature measuring module, the third temperature measuring module and the third water level measuring module are electrically connected with a signal receiving end of the controller, a control end of the controller is electrically connected with the drain regulating valve of the heater, a man-machine interaction end of the controller is electrically connected with a touch screen, the first temperature measuring module is used for measuring the outlet water temperature of a high-pressure heater, the pressure measuring module is used for measuring the extraction pressure of a steam turbine, the second temperature measuring module and the third temperature measuring module are respectively used for measuring the inlet water temperature and the drain temperature of the heater, the touch screen is used for setting the upper end difference and the lower end difference of the heater, displaying the end difference and setting the water level, and the adjusting device can realize the automatic adjustment of the end difference of the heater in a wide load range of the unit and is more accurate in adjustment.
The utility model has the advantages that: compared with the prior art, the utility model discloses can carry out data acquisition to high pressure feed water heater upper and lower end difference, introduce high pressure feed water heater water level regulation control with the end difference, can realize the unit at the automatically regulated of wide load within range heater end difference, adjust more accurately.
Drawings
FIG. 1 is a schematic flow diagram of a high-pressure heater of a thermal generator set;
FIG. 2 is a schematic diagram of the water level control principle of the high pressure heater;
fig. 3 is a schematic diagram of the principle of the end difference control of the adaptive high-pressure heater.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
At present, the water level control schematic diagram of most high-pressure heaters of thermal power generating units is shown in the attached figure 2, and the functions of all modules of the control diagram are explained as follows:
l water level measuring module 2: and measuring the water level value W1 of the high-pressure heater in real time.
l water level setting module 1: setting a heater desired control water level value.
l PID controller 3: a pid (proportion Integration differentiation) controller, i.e., a proportional-integral-derivative controller.
l heater drain regulating valve: regulating valves, i.e. actuators in the system.
The system measures the water level value W1 of the heater in real time through the water level measuring module 2, and the water level deviation value delta W is formed by subtracting the set value of the water level setting module 1 and is output to the PID controller 3, when the delta W is a positive value, the actual water level is higher than the control water level, the PID controller 3 outputs an instruction to control the opening of a drain control valve of the heater, after the valve is opened to a large extent, the drain quantity flowing out of the heater is increased, and the water level of the heater is reduced; when the delta W is a negative value, the actual water level is lower than the control water level, the PID controller 3 outputs an instruction to control the drain control valve of the heater to close, after the valve is closed, the drain quantity flowing out of the heater is reduced, and the water level of the heater is increased. By the closed-loop control adjustment of the water level of the heater, the PID controller 3 stops outputting until the deviation value 'delta W' is smaller than the expected value range.
The water level of the heater can be effectively controlled by the method, but the water level cannot intuitively reflect whether the end difference of the high-pressure heater under the operation working condition is optimal or not (the value can refer to a design value or be determined through experiments). Most thermal power plants need to calculate the end difference of the heater, after the saturation temperature corresponding to the extraction pressure of the heater is obtained by looking up a table under the line, calculation is carried out according to the definition of the upper end difference and the lower end difference, and then the water level of the heater is manually adjusted by utilizing the end difference result obtained by calculation. The process needs repeated calculation and adjustment, is complicated, has high labor intensity, and can affect the safe operation of the unit due to careless adjustment.
Therefore, the utility model provides a following thermal power unit heater end difference self-adaptation adjusting method and thermal power unit heater end difference self-adaptation adjusting device has solved foretell problem.
Example 1: as shown in fig. 3, a thermal power generating unit heater end difference adaptive adjustment method includes the following steps:
(1) after the high-pressure heater end difference automatic control system is put into the system, the pressure measuring module 1 measures the steam extraction pressure P of the heater in real time and sends the steam extraction pressure P to the saturation temperature calculating module 3, and the saturation temperature calculating module 3 calculates the corresponding saturation temperature value T2 according to the pressure P value;
(2) the difference value delta T1 between the calculated saturation temperature value T2 and the measured temperature T1 measured by the temperature measuring module I2 is the upper end difference of the heater; simultaneously, the temperature measuring module II 4 and the temperature measuring module III 5 respectively measure the water inlet temperature T3 and the water drainage temperature T4 of the heater, and the difference value delta T2 between the water inlet temperature T3 and the water drainage temperature T4 is the lower end difference of the heater;
(3) comparing the Δ T1 and the Δ T2 with a set value T5 of the first end difference setting module 6 and a set value T6 of the second end difference setting module 8 respectively to obtain difference values Δ T11 and Δ T21 (obtaining a deviation value between the actual operation end difference and the set "optimal end difference"), and displaying the Δ T1 and the Δ T2 through an end difference display module 7;
(4) inputting the difference values delta T11 and delta T21 into a weighting coefficient input/output module 9 for weighting calculation to obtain weighted difference values n multiplied by delta T11 and (1-n) delta T21, wherein the weighting coefficient n represents the proportion of the upper and lower end differences in the economic operation of the unit heater and can be obtained according to the experience or experiment of operators;
(5) inputting the weighted difference n x Δ T11 and (1-n) x Δ T21 into a comparison output module I10 for comparison, and outputting Δ W1 if the weighted difference is greater than zero and greater than zero,
that is, when n.times.DELTA.T 11 > 0, and n.times.DELTA.T 11 > (1-n). times.DELTA.T 21; then Δ W1 ═ nxΔ T11;
when (1-n) × Δ T21 > 0, and (1-n) × Δ T21 > n × Δ T11; then Δ W1 ═ (1-n) × Δ T21;
Δ W1 represents the output value of the comparison output module one 10;
(6) when the delta W1 is less than or equal to 0, the delta W1 is sent to a comparison output module III 14 for comparison output, the delta W is equal to delta W2, the delta W represents the output value of the comparison output module III 14, the delta W2 represents the difference between the water level setting module 12 and the water level measuring module 13, when the delta W1 is more than 0, the delta W is equal to delta W1, and the delta W1 represents the value of a comparison output module I10, namely when the operating end difference of the heater is deviated from the expected end difference, the control system takes the end difference deviation value as the input value of a PID controller 15, the output value calculated by the PID controller 15 is used as the valve opening degree control of a drain regulating valve 16 of the heater to control the water level of the heater indirectly, the measured value W1 of the water level measuring module 13 and the value delta W1 of the comparison output module I10 are sent to a comparison output module II 11 for comparison, and when the delta W1 is less than or equal to 0, the heater is operated in a more reasonable end difference range, and comparing the output value delta W3 of the second output module 11 with the output value delta W1, giving the measured water level value to the set water level value, namely, the PID controller does not output, and maintaining the water level to operate, so that the system can realize undisturbed connection of water level control and end difference control in the switching process.
Example 2: as shown in fig. 3, a thermal power generating unit heater end difference adaptive regulator includes a first temperature measuring module 2, a first pressure measuring module 1, a second temperature measuring module 4, a third temperature measuring module 5, a second water level measuring module 13, a controller and a heater drain regulating valve 16, wherein the first temperature measuring module 2, the first pressure measuring module 1, the second temperature measuring module 4, the third temperature measuring module 5 and the second water level measuring module 13 are all electrically connected with a signal receiving end of the controller, a control end of the controller is electrically connected with the heater drain regulating valve 16, a man-machine interaction end of the controller is electrically connected with a touch screen (or a DCS system), the first temperature measuring module 2 is used for measuring an outlet water temperature of a high-pressure heater, the first pressure measuring module 1 is used for measuring a steam extraction pressure from a steam turbine, and the second temperature measuring module 4 and the third temperature measuring module 5 are respectively used for measuring an inlet water temperature, the water level measuring module 13 is used for the water level of the heater, the drain regulating valve 16 of the heater is used for controlling the water level of the heater, the touch screen is used for setting the upper end difference and the lower end difference of the heater, displaying the end differences and setting the water level, and the regulating device can realize the automatic regulation of the end differences of the heater in a wide load range of a unit and is more accurate in regulation.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention, therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (1)
1. The utility model provides a thermal power unit heater end difference self-adaptation adjusting device which characterized in that: the temperature measuring module II and the temperature measuring module III are respectively used for measuring the water inlet temperature and the water drainage temperature of the heater, the water level measuring module is used for controlling the water level of the heater, the touch screen is used for setting the upper end difference and the lower end difference of the heater, and the water level measuring module II and the temperature measuring module III are respectively used for measuring the water inlet temperature and the water drainage temperature of the heater Displaying end difference and setting water level.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110056858A (en) * | 2019-05-15 | 2019-07-26 | 贵州电网有限责任公司 | A kind of fired power generating unit Heater Terminal Temperature Difference adaptive regulation method and device |
| WO2022037271A1 (en) * | 2021-02-26 | 2022-02-24 | 中广核工程有限公司 | Liquid level control method, apparatus and device for deaerator of nuclear power unit |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110056858A (en) * | 2019-05-15 | 2019-07-26 | 贵州电网有限责任公司 | A kind of fired power generating unit Heater Terminal Temperature Difference adaptive regulation method and device |
| WO2022037271A1 (en) * | 2021-02-26 | 2022-02-24 | 中广核工程有限公司 | Liquid level control method, apparatus and device for deaerator of nuclear power unit |
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