Automatic liquid level adjusting system and method for double deaerators

Abstract

The invention discloses a double-deaerator liquid level automatic adjusting system and method, and relates to the technical field of double-deaerator liquid level automatic adjusting, the double-deaerator liquid level automatic adjusting system comprises two deaerators, the two deaerators are medium-pressure rotating film type deaerators, the two deaerators are connected through a steam side balance pipe and a water side balance pipe, and the two deaerators are connected through a steam side balance pipe and a water side balance pipe; the steam side balance pipe is used for balancing the pressure in the two deaerators, and the water side balance pipe is used for balancing the water levels of the two deaerators; each deaerator is provided with at least one pressure transmitter and at least four water level transmitters which are used for monitoring the pressure and the liquid level of the deaerator. The system solves the problem that the balance pipe on the steam-water side of the deaerator cannot self-balance the liquid level when the thermal load change is large, the steam extraction control valve and the water replenishing control valve are automatically controlled through the automatic control logic to always stabilize the pressure liquid level of the deaerator group at the set value of the control end of the DCS central control system, the stability of the deaeration water supply operation condition is greatly improved, and the energy consumption of the deaerator group is reduced. And the operation amount of operation monitoring personnel is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of automatic liquid level regulation for double deaerators, and in particular to a system and method for automatic liquid level regulation for double deaerators. Background Art

[0002] Modern thermal power plant units are showing a trend of intelligent development, and the requirements for the operation and management of thermal power plant equipment are also constantly increasing. According to the requirements of the "Design Specifications for Small Thermal Power Plants" (GB50049-2011), the steam and water pipelines of multiple deaerators with the same parameters should adopt a mother pipe control system, and the surplus required for the safe operation of the feedwater pump is 3kPa~5kPa, and the deaerator and feedwater tank should be equipped with a safety valve and exhaust pipe to prevent overpressure explosion. When the unit is running stably, the deaerator liquid level can be automatically controlled by adjusting the condensate pump frequency and the opening of the desalted water replenishment valve, but when the heat load fluctuates, automatic control cannot be guaranteed, and manual intervention or manual operation is still required. When the heat load fluctuates greatly, the feedwater flow, condensate flow, and deaerator recovery drain pressure and temperature change greatly, causing deviations in the pressure and liquid level of multiple deaerators, and water grabbing in each deaerator, which can seriously lead to accidents such as water inflow into the steam extraction pipeline and cavitation of the feedwater pump. The traditional single-loop liquid level control method only adjusts the water replenishment volume after the liquid level changes. It cannot quickly stabilize the deaerator pressure level and cannot ensure the long-term stable operation of the deaerator water supply system.

[0003] Therefore, it is urgent to propose a dual deaerator liquid level automatic adjustment system and method. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the problems existing in the existing double deaerator liquid level automatic adjustment system, the present invention is proposed.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a dual deaerator liquid level automatic adjustment system, comprising:

[0007] Two deaerators, wherein the deaerators are medium-pressure rotary film deaerators, and the two deaerators are connected via a steam-side balancing pipe and a water-side balancing pipe. The steam-side balancing pipe is used to balance the pressures in the two deaerators, and the water-side balancing pipe is used to balance the water levels of the two deaerators;

[0008] Each deaerator is equipped with at least one pressure transmitter and at least four water level transmitters to monitor the pressure and liquid level of the deaerator;

[0009] A DCS central control system, which is used to receive data from the pressure transmitter and the water level transmitter;

[0010] PI controller, which is used to automatically adjust the opening of the deionized water replenishment regulating valve according to the difference between the liquid level set value of the deaerator and the actual liquid level average value;

[0011] The PID controller is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator and the set pressure.

[0012] As a preferred solution of the dual deaerator liquid level automatic adjustment system of the present invention, the DCS central control system regards the two deaerators as a connected container and makes the pressures of the two deaerators tend to be consistent through pressure control logic.

[0013] As a preferred solution of the dual deaerator liquid level automatic adjustment system of the present invention, the parameters of the PI controller include a proportional coefficient Kp and an integral time constant Ki, which are adjusted through experiments to meet the actual operation water replenishment demand.

[0014] As a preferred solution of the dual deaerator liquid level automatic adjustment system of the present invention, the parameters of the PID controller include a proportional coefficient Kp, an integral time constant Ki and a differential time constant Kd, which are adjusted through experiments to adapt to disturbances in actual operation.

[0015] As a preferred solution of the dual deaerator liquid level automatic adjustment system of the present invention, wherein: the dual deaerator liquid level automatic adjustment system also includes a liquid level difference conversion mechanism, which converts the actual liquid level difference of the two deaerators into pressure compensation to adjust the liquid level of the deaerator;

[0016] The liquid level difference conversion mechanism includes a conversion coefficient M, which is used to divide the liquid level difference H by the conversion coefficient M to obtain the deaerator liquid level compensation converted pressure Px.

[0017] Beneficial effects of the present invention: This system solves the problem that the balance pipe on the steam-water side of the deaerator cannot balance the liquid level by itself when the heat load changes greatly. The system automatically controls the steam extraction regulating valve and the water replenishment regulating valve through automatic control logic to keep the pressure liquid level of the deaerator group stable at the control end set value of the DCS central control system, greatly improving the stability of the deaerator water supply operating conditions and reducing the operation workload of the operation monitoring personnel.

[0018] In view of the problems existing in the above-mentioned existing method for automatic liquid level adjustment of double deaerators, the present invention is proposed.

[0019] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for automatically adjusting the liquid level of a double deaerator, applied to any of the above-mentioned automatic liquid level adjustment systems of a double deaerator, comprising the following steps:

[0020] S1: Monitor the liquid level and pressure of each deaerator in real time through at least four water level transmitters and one pressure transmitter;

[0021] S2: using the DCS central control system to receive data from the pressure transmitter and the water level transmitter;

[0022] S3: Calculate the average reading of the two deaerator liquid level sensors and compare it with the set value to obtain the liquid level deviation;

[0023] S4: Use the PI controller to automatically adjust the opening of the desalted water replenishment regulating valve according to the liquid level deviation to keep the actual liquid level close to the set value;

[0024] S5: The two deaerators are regarded as a connected container, and the pressure of the two deaerators is made consistent through pressure control logic;

[0025] S6: Use the PID controller to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator and the set pressure to change the secondary extraction steam inlet amount and adjust the actual pressure of the deaerator;

[0026] S7: Under the premise that the pressure of the deaerator is stable under the single-loop PID control of the deaerator secondary extraction valve, the actual liquid level difference H of the two deaerators is calculated and converted into the pressure compensation Px;

[0027] S8: The secondary extraction steam regulating valves of the two deaerators will be adjusted according to the compensated set pressures. Under the action of the pressure difference, the deaerator liquid level will be quickly balanced through the water side balance pipe.

[0028] As a preferred solution of the method for automatic liquid level adjustment of the dual deaerator of the present invention, the parameters of the PI controller include a proportional coefficient Kp and an integral time constant Ki, which are adjusted through experiments to meet the actual operation water replenishment demand.

[0029] As a preferred solution of the dual deaerator liquid level automatic adjustment method of the present invention, the parameters of the PID controller include the proportional coefficient Kp, the integral time constant Ki and the differential time constant Kd, which are adjusted through experiments to adapt to the disturbance in actual operation.

[0030] As a preferred embodiment of the method for automatic liquid level adjustment of dual deaerators of the present invention, in step S7, the liquid level difference H is divided by the conversion coefficient M to obtain the deaerator liquid level compensation conversion pressure Px.

[0031] As a preferred embodiment of the method for automatically adjusting the liquid level of dual deaerators of the present invention, if the pressure setting value of one deaerator is P1, the pressure setting value of the other deaerator is P2, and the liquid level of the deaerator with the pressure setting value of P1 is higher than that of the other deaerator, the pressure setting value of the deaerator with the pressure setting value of P1 is P1+Px, and the pressure setting value of the other deaerator is P2-Px;

[0032] Among them, the pressure setting values ​​P1 and P2 are both set by the operation end of the DCS central control system, both with a rated pressure of 0.27Mpa, and M is the empirical coefficient;

[0033] Px is calculated in real time based on the deaerator liquid level difference H and the conversion coefficient M. The larger the deaerator liquid level difference H, the larger Px is. If the liquid level difference does not exist, Px returns to zero.

[0034] The beneficial effects of the present invention are as follows: the DCS central control system is used to receive data from the pressure transmitter and the water level transmitter, and the PI controller is used to automatically adjust the opening of the desalted water replenishment regulating valve according to the difference between the liquid level setting value of the deaerator and the actual liquid level average value, so as to keep the actual liquid level close to the setting value; the PID controller is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator and the set pressure, so as to quickly respond to the disturbance caused by the change of the external heat load. Under the premise that the pressure of the deaerator is stable under the single-loop PID control of the secondary steam extraction regulating valve of the deaerator, the actual liquid level difference between the two deaerators is calculated and converted into pressure compensation to further balance the liquid level of the deaerator. The parameters of the PI controller and the PID controller are adjusted through experiments to meet the actual operation replenishment demand and adapt to the disturbance in the actual operation, thereby improving the effectiveness and flexibility of the control strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0036] Figure 1 It is a schematic diagram of the deaerator liquid level automatic adjustment system described in the present invention.

[0037] Figure 2 It is a schematic diagram of the deaerator liquid level automatic adjustment system described in the present invention. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0041] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0042] Example 1

[0043] Reference Figure 1-2 , which is the first embodiment of the present invention, provides a dual deaerator liquid level automatic adjustment system, comprising:

[0044] Two deaerators 100, the deaerator 100 adopts a medium-pressure rotary film deaerator 100, and the two deaerators 100 are connected through a steam-side balancing pipe 101 and a water-side balancing pipe 102, the steam-side balancing pipe 101 is used to balance the pressure in the two deaerators 100, and the water-side balancing pipe 102 is used to balance the water level of the two deaerators 100; each deaerator 100 is equipped with at least one pressure transmitter 103 and at least four water level transmitters 104, which are used to monitor the pressure and liquid level of the deaerator 100; a DCS central control system 400, which is used to receive data from the pressure transmitter 103 and the water level transmitter 104; a PI controller 200, which is used to automatically adjust the opening of the desalted water replenishment regulating valve according to the difference between the liquid level setting value of the deaerator 100 and the actual liquid level average value; a PID controller 300, which is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator 100 and the set pressure.

[0045] The thermal power plant is equipped with three boilers and two steam turbines, and adopts the main pipe control operation mode. The heating steam source of the deaerator 100 comes from the second-stage steam extraction main pipe of the steam turbine, the water source of the deaerator 100 mainly comes from the condensate main pipe, and the make-up water comes from the chemical desalted water. In addition, the deaerator 100 is the only mixed heater in the steam-water system, which collects the first and second stage drains of the air preheater and the SGH drain.

[0046] The DCS central control system 400 regards the two deaerators 100 as a connected container and makes the pressures of the two deaerators 100 tend to be consistent through pressure control logic.

[0047] The parameters of the PI controller 200 include a proportional coefficient Kp and an integral time constant Ki, which are adjusted through experiments to meet the actual operating water replenishment requirements.

[0048] The parameters of the PID controller 300 include a proportional coefficient Kp, an integral time constant Ki and a differential time constant Kd, which are adjusted through experiments to adapt to disturbances in actual operation.

[0049] Since the water pipes of the two deaerators 100 are mother pipes and are equipped with steam side balance pipes 101 and water side balance pipes 102, the two deaerators 100 can be regarded as connected containers. When the pressure of the two deaerators 100 is completely consistent, the liquid levels of the two water tanks of the connected container will inevitably tend to be consistent. However, in actual operation, due to the pipeline installation errors and uneven resistance of the check valves, the high-temperature and high-pressure heat sources entering the two deaerators 100 are unevenly distributed, especially when the high-pressure drain flow rate changes greatly, which will cause the pressure of the deaerator 100 to suddenly change. Limited by the complex operating conditions of the deaerator 100 with a large change in heat load and the error of the pressure transmitter 103 measurement data itself, the single-loop control of the pressure of the two deaerators 100 is consistent, and it cannot absolutely guarantee that the liquid level of the deaerator 100 is stable. When abnormal conditions occur, the liquid level of the deaerator 100 will inevitably have a small level deviation of 100mm to 200mm.

[0050] Therefore, this design adopts the method of converting the liquid level of the deaerator 100 into pressure compensation for liquid level adjustment, and adds the calculation of the actual liquid level difference H of the two deaerators 100, and converts the difference H into pressure compensation to the pressure control logic of the two deaerators 100.

[0051] The dual deaerator liquid level automatic adjustment system also includes a liquid level difference conversion mechanism, which converts the actual liquid level difference between the two deaerators 100 into pressure compensation to adjust the liquid level of the deaerator 100; the liquid level difference conversion mechanism includes a conversion coefficient M, which is used to divide the liquid level difference H by the conversion coefficient M to obtain the deaerator 100 liquid level compensation converted pressure Px.

[0052] In summary, this system automatically controls the steam extraction regulating valve and the water supply regulating valve through automatic control logic, and stabilizes the pressure and liquid level of the deaerator group 100 at the control end set value of the DCS central control system 400, thereby greatly improving the stability of the deaerator feed water operation condition. The system reduces the operation workload of the operation monitoring personnel and reduces the need for manual intervention. By balancing the pressure and water level of the two deaerators 100, it effectively prevents accidents such as water ingress into the steam extraction pipeline and cavitation of the feed water pump caused by pressure and liquid level deviations.

[0053] By using PI controller 200 and PID controller 300, automatic adjustment is performed according to the deviation between the actual liquid level and pressure and the set value, thereby improving the adjustment accuracy and response speed. The controller parameters (proportional coefficient Kp, integral time constant Ki, differential time constant Kd) are adjusted through experiments to adapt to the disturbances in actual operation, thereby enhancing the adaptability of the system.

[0054] In addition, the system also includes a liquid level difference conversion mechanism, which converts the actual liquid level difference between the two deaerators 100 into pressure compensation to more accurately adjust the liquid level of the deaerator 100, thereby solving the problem that the balance pipe 102 on the steam-water side of the deaerator 100 cannot self-balance the liquid level when the heat load changes greatly.

[0055] Example 2

[0056] Reference Figure 1-2 , which is the second embodiment of the present invention, and which is different from the first embodiment in that: a method for automatically adjusting the liquid level of a double deaerator, applied to any of the above-mentioned automatic liquid level adjustment systems of a double deaerator, comprises the following steps,

[0057] S1: Real-time monitoring of the liquid level and pressure of each deaerator 100 through four water level transmitters 104 and one pressure transmitter 103;

[0058] S2: using the DCS central control system 400 to receive data from the water level transmitter 104 and the pressure transmitter 103;

[0059] S3: Optimize the water level values ​​of the magnetic flap liquid level sensor, the electric node liquid level sensor, and the balance container liquid level sensor, calculate the average reading of the two deaerator 100 liquid level sensors, and compare it with the set value to obtain the liquid level deviation;

[0060] S4: Use PI controller 200 to automatically adjust the opening of the desalted water replenishment regulating valve according to the liquid level deviation to keep the actual liquid level close to the set value; in the PI control setting process, set the differential time constant to infinity, change the liquid level set value, observe the Tr rise time, gradually increase the proportional coefficient Kp, and gradually reduce the rise time Tr until the rise time Tr and the peak time Tm basically meet the actual operation replenishment demand. At this time, reduce the proportional coefficient Kp by 20%, gradually reduce the integral time, make the adjustment time as short as possible, and make the overshoot as small as possible. The formula of PI controller 200 is as follows:

[0061] OP(n)=OP(n-1)+(Kp*(error(n)-error(n-1))+Ki*error(n))*(HROP-LROP);

[0062] In the automatic control liquid level mode, the liquid level tracking value of the PI controller 200 of the two deaerators 100 water supply regulating valve is the average of the two deaerators 100 liquid levels, that is, the opening of the deionized water supply regulating valve of the two deaerators 100 is always consistent, and the minimum valve position opening of the automatic control mode is set to 5%, and the maximum valve position opening is 50%.

[0063] S5: The two deaerators 100 are regarded as a connected container, and the pressure of the two deaerators 100 is made consistent through the pressure control logic. The deionized water replenishment regulation only participates in the water volume regulation in the pressure container, and does not participate in the liquid level balance regulation, so as to avoid the liquid level fluctuation caused by the inconsistent pressure of the two deaerators 100. The erroneous excessive adjustment is made according to the instantaneous liquid level or the false liquid level, resulting in a large amount of cold source entering, causing the unstable working condition of the deoxygenated water supply system to be further deteriorated;

[0064] S6: The rated operating pressure of the deaerator 100 is 0.27 MPa. The PID controller 300 is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator 100 and the set pressure to change the secondary extraction steam inlet amount and adjust the actual pressure of the deaerator 100;

[0065] S7: Under the premise that the pressure of the deaerator 100 is stable under the single-loop PID control of the secondary steam extraction valve of the deaerator 100, the actual liquid level difference H between the two deaerators 100 is calculated and converted into the pressure compensation Px;

[0066] S8: The two deaerator 100 second-stage steam extraction regulating valves will be adjusted according to the compensated set pressures respectively. Under the effect of the pressure difference, the liquid level of the deaerator 100 will be quickly balanced through the water-side balance pipe 102.

[0067] In summary, this method realizes real-time control of the liquid level of the deaerator 100 by real-time monitoring of the liquid level and pressure of each deaerator 100 and using the DCS central control system 400 to receive data. By calculating the average reading of the liquid level sensors of the two deaerators 100 and comparing it with the set value to obtain the liquid level deviation, the PI controller 200 is used to automatically adjust the opening of the desalted water replenishment regulating valve to keep the actual liquid level close to the set value. The two deaerators 100 are regarded as a connected container, and the pressure of the two deaerators 100 is made consistent through the pressure control logic, reducing the liquid level fluctuation caused by inconsistent pressure. The PID controller 300 is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator 100 and the set pressure, and quickly respond to the disturbance caused by the change of external heat load.

[0068] Under the premise that the pressure of the deaerator 100 is stable under the single-loop PID control of the deaerator 100 with the secondary steam extraction valve, this method calculates the actual liquid level difference between the two deaerators 100 and converts it into pressure compensation to further balance the liquid level of the deaerator 100. This method also adjusts the parameters of the PI controller 200 and the PID controller 300 through experiments to meet the actual operation water replenishment requirements and adapt to the disturbances in the actual operation, thereby improving the effectiveness and flexibility of the control strategy. These measures jointly improve the operating efficiency and safety of the deaerator 100 in the thermal power plant, reduce the operating cost, and improve the automation level of the system.

[0069] The remaining structures are the same as those of Example 1.

[0070] Example 3

[0071] Reference Figure 1-2 , which is the third embodiment of the present invention. This embodiment is different from the second embodiment in that the parameters of the PI controller 200 include the proportional coefficient Kp and the integral time constant Ki, which are adjusted through experiments to meet the actual operation water replenishment demand. The secondary extraction steam inlet regulating valve is controlled by the PID controller 300 to achieve single-loop control of the pressure of each deaerator 100, so that the actual operating pressure of the deaerator 100 is maintained at the operating pressure setting value of the deaerator 100 of the DCS central control system 400.

[0072] During the PID control tuning process, the differential time constant is set to infinity. The operator manually adjusts the deaerator 100 pressure to the rated pressure and stabilizes it. Then, the proportional coefficient Kp is slowly increased from 0. After the automatic control is put into operation, the deaerator 100 pressure can maintain the rated pressure. Then, the set value is increased, and the rise time Tr and overshoot are observed. While ensuring that the overshoot is as small as possible, the adjustment time Ts is reduced. After being put into operation, the change trend is observed, and the integral differential time constant is gradually reduced until a 4:1 attenuation oscillation occurs, and then the integral time constant is called back. After observing the ability of the PID regulator to resist actual operating disturbances, the differential link is appropriately increased so that it can quickly and smoothly overcome the response caused by changes in external heat load, and the system can quickly return to a state without interference after the disturbance disappears, and always maintain a relatively ideal steady-state error.

[0073] In S6, the PID controller 300 formula is as follows:

[0074] OP(n)=OP(n-1)+(Kp*(error(n)-error(n-1))+Ki*error(n)+Kd*error(n)-2*error(n-1)+error(n-2))*(HROP-LROP));

[0075] Wherein Ki = Kp*Ts / Ti, Kd = Kp*TD / Ts, Ts is the DPU operation cycle, Ts is 200ms, OP(n) is the actual opening of the deaerator 100 secondary steam inlet regulating valve, n is the DPU sampling time, error(n) is the deviation between the current actual pressure and the set pressure, error(n-1) is the deviation between the actual pressure and the set pressure in the previous operation cycle, i.e. 200ms ago, HROP and LROP are the upper and lower limits of the valve in the automatic control mode, Kp is the proportional coefficient, Ki is the integral time constant, and Kd is the differential time constant;

[0076] Through experimental adjustments, it can adapt to the disturbances in actual operation.

[0077] In S7, the liquid level difference H is divided by the conversion coefficient M to obtain the liquid level compensation converted pressure Px of the deaerator 100.

[0078] If the pressure setting value of one deaerator 100 is P1, the pressure setting value of the other deaerator 100 is P2, and the liquid level of the deaerator 100 with the pressure setting value of P1 is higher than that of the other deaerator 100, then the pressure setting value of the deaerator 100 with the pressure setting value of P1 is P1+Px, and the pressure setting value of the other deaerator 100 is P2-Px; wherein, the pressure setting values ​​P1 and P2 are both set by the operation end of the DCS central control system 400, and both are rated pressures of 0.27Mpa, and M is an empirical coefficient;

[0079] The converted pressure Px is calculated in real time according to the liquid level difference H of the deaerator 100 and the conversion coefficient M. The larger the liquid level difference H of the deaerator 100 is, the larger Px is. If the liquid level difference does not exist, Px returns to zero.

[0080] The remaining structure is the same as that of Example 2.

[0081] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0082] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0083] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A dual deaerator liquid level automatic adjustment system, characterized in that: include, Two deaerators (100), wherein the deaerators (100) are medium-pressure rotary film deaerators (100), and the two deaerators (100) are connected via a steam-side balancing pipe (101) and a water-side balancing pipe (102), wherein the steam-side balancing pipe (101) is used to balance the pressures in the two deaerators (100), and the water-side balancing pipe (102) is used to balance the water levels in the two deaerators (100); Each deaerator (100) is equipped with at least one pressure transmitter (103) and at least four water level transmitters (104) for monitoring the pressure and liquid level of the deaerator (100); A DCS central control system (400), which is used to receive data from the pressure transmitter (103) and the water level transmitter (104); A PI controller (200) for automatically adjusting the opening of a deionized water replenishment regulating valve according to a difference between a liquid level setting value and an actual liquid level average value of the deaerator (100); A PID controller (300) is used to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator (100) and the set pressure.

2. The dual deaerator liquid level automatic adjustment system according to claim 1 is characterized in that: The DCS central control system (400) regards the two deaerators (100) as a connected container, and makes the pressures of the two deaerators (100) tend to be consistent through pressure control logic.

3. The dual deaerator liquid level automatic adjustment system according to claim 2 is characterized in that: The parameters of the PI controller (200) include a proportional coefficient Kp and an integral time constant Ki, which are adjusted through experiments to meet the actual operation water replenishment demand.

4. The dual deaerator liquid level automatic adjustment system according to claim 3 is characterized in that: The parameters of the PID controller (300) include a proportional coefficient Kp, an integral time constant Ki and a differential time constant Kd, which are adjusted through experiments to adapt to disturbances in actual operation.

5. The dual deaerator liquid level automatic adjustment system according to claim 4 is characterized in that: The dual deaerator liquid level automatic adjustment system further comprises a liquid level difference conversion mechanism, which converts the actual liquid level difference of the two deaerators (100) into pressure compensation to adjust the liquid level of the deaerator (100); The liquid level difference conversion mechanism comprises a conversion coefficient M, which is used to divide the liquid level difference H by the conversion coefficient M to obtain the deaerator (100) liquid level compensation converted pressure Px.

6. A method for automatically adjusting the liquid level of a double deaerator, applied to the automatic liquid level adjustment system of a double deaerator as claimed in any one of claims 1 to 5, characterized in that: The following steps are included: S1: real-time monitoring of the liquid level and pressure of each deaerator (100) through at least four water level transmitters (104) and one pressure transmitter (103); S2: using the DCS central control system (400) to receive data from the pressure transmitter (103) and the water level transmitter (104); S3: Calculate the average reading of the liquid level sensors of the two deaerators (100), and compare it with the set value to obtain the liquid level deviation; S4: using a PI controller (200) to automatically adjust the opening of the desalted water replenishment regulating valve according to the liquid level deviation, so as to keep the actual liquid level close to the set value; S5: The two deaerators (100) are regarded as a connected container, and the pressures of the two deaerators (100) are made consistent through pressure control logic; S6: using a PID controller (300) to automatically adjust the opening of the secondary steam inlet regulating valve according to the deviation between the actual pressure of the deaerator (100) and the set pressure to change the secondary extraction steam inlet amount and adjust the actual pressure of the deaerator (100); S7: Under the premise that the pressure of the deaerator (100) is stable under the single-loop PID control of the secondary steam extraction valve of the deaerator (100), the actual liquid level difference H of the two deaerators (100) is calculated and converted into a pressure compensation Px; S8: The secondary extraction steam regulating valves of the two deaerators (100) will be adjusted respectively according to the compensated set pressure. Under the effect of the pressure difference, the liquid level of the deaerator (100) will be quickly balanced through the water side balance pipe (102).

7. The method for automatic liquid level adjustment of a double deaerator according to claim 6, characterized in that: The parameters of the PI controller (200) include a proportional coefficient Kp and an integral time constant Ki, which are adjusted through experiments to meet the actual operating water replenishment requirements.

8. The method for automatic liquid level adjustment of a double deaerator according to claim 7, characterized in that: The parameters of the PID controller (300) include a proportional coefficient Kp, an integral time constant Ki and a differential time constant Kd, which are adjusted through experiments to adapt to disturbances in actual operation.

9. The method for automatic liquid level adjustment of a double deaerator according to claim 8, characterized in that: In S7, the liquid level difference H is divided by the conversion coefficient M to obtain the deaerator (100) liquid level compensation converted pressure Px.

10. The method for automatic liquid level adjustment of a double deaerator according to claim 9, characterized in that: If the pressure setting value of one of the deaerators (100) is P1, the pressure setting value of the other deaerator (100) is P2, and the liquid level of the deaerator (100) with the pressure setting value P1 is higher than that of the other deaerator (100), then the set pressure of the deaerator (100) with the pressure setting value P1 is P1+Px, and the pressure setting value of the other deaerator (100) is P2-Px; The pressure setting values ​​P1 and P2 are both set by the operation end of the DCS central control system (400), both are rated pressures of 0.27 MPa, and M is an empirical coefficient; Px is calculated in real time according to the liquid level difference H of the deaerator (100) and the conversion coefficient M. The larger the liquid level difference H of the deaerator (100), the larger Px is. If the liquid level difference does not exist, Px returns to zero.

Images