A marine boiler multi-pump parallel operation feed water control method and its system

Abstract

The present application relates to a multi-pump parallel operation feed water control method and system for a marine boiler, which includes: before the successful parallel operation of the turbine feed water pumps, performing an initial adjustment of the opening degrees of the feed water regulating valve and the steam small flow rate discharge valve; obtaining the steam pressure of the boiler after the successful parallel operation of the turbine feed water pumps, and determining whether the steam pressure is within the target pressure range after the rising working condition; if not, adjusting the feed water regulating valve and the steam small flow rate discharge valve again, and adjusting the steam inlet regulating valve on the turbine feed water pump until the steam pressure is within the target pressure range after the rising working condition. In the present invention, before the successful parallel operation of the turbine feed water pumps, an initial adjustment of the opening degrees of the feed water regulating valve and the steam small flow rate discharge valve is performed in advance. When the system changes the working condition, the steam pressure generated by the boiler is controlled by the feed water regulating valve and the steam small flow rate discharge valve, the "positive feedback" phenomenon is suppressed, the steady-state and variable working condition control of the device is realized, and the oscillation of the steam pressure and the steam superheat degree during the parallel operation process is prevented.

Description

Technical Field

[0001] The present application relates to the technical field of boiler thermal systems, and in particular to a method and system for controlling multi-pump parallel feedwater for a marine boiler. Background Art

[0002] Marine supercritical boilers have the characteristics of small thermal inertia and sensitive parameter changes. Due to their inherent characteristics, they are more difficult to control than conventional marine boilers. The marine supercritical boiler feed water control system is limited by the space of the ship and is equipped with a turbine water pump. At the same time, in order to meet the needs of various working conditions, multiple turbine feed water pumps are configured. The steam generated by the boiler is used as the power of the turbine water pump. When the working conditions change, multiple feed water pumps are required to work at the same time to meet the system working requirements. In the process of parallel operation of the feed water pumps, problems such as runaway, unstable steam pressure and superheat control often occur. The traditional method of using turbine feed water pumps to control the feed water regulating valve pressure difference and feed water regulating valves to control steam pressure has system coupling, violent oscillation of the control target, and a long time for the control target to stabilize.

[0003] Specifically, it is the "positive feedback" phenomenon of the steam pressure of the device:

[0004] In the feedwater control system, the turbine feedwater pump speed control system and the steam generator pressure control system will experience "positive feedback" when the device pressure fluctuates. "Positive feedback" means that in order to increase the steam pressure, the feedwater regulating valve is opened, and the turbine feedwater pump speed increases. While increasing the steam pressure, the feedwater pump speed and steam pressure continue to increase due to the increase in the steam intake of the turbine feedwater pump. At the same time, as the feedwater pump speed increases, the efficiency of the feedwater pump also increases. The superposition of these three factors causes the steam pressure to continue to rise, increasing the difficulty of control. Summary of the invention

[0005] The embodiment of the present application provides a method and system for controlling water supply of a multi-pump parallel operation of a marine boiler, so as to solve the problem in the related art that control is difficult when the steam pressure continues to rise.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for controlling water supply of a multi-pump parallel operation of a marine boiler, comprising:

[0007] Before the turbine feedwater pump is successfully connected, the feedwater regulating valve and the steam small flow discharge valve should be initially adjusted for opening;

[0008] Obtain the steam pressure of the boiler after the turbine feed water pump is successfully connected, and determine whether the steam pressure is within the target pressure range after the operating condition is upgraded;

[0009] If not, adjust the feed water regulating valve and the small steam flow discharge valve again, and adjust the steam inlet regulating valve on the turbine feed water pump until the steam pressure is within the target pressure range after the operating condition is increased.

[0010] In some embodiments, the initial opening adjustment of the feed water regulating valve and the steam small flow discharge valve includes the following steps:

[0011] Obtain the steam pressure of the boiler before the successful synchronization of the turbine feed water pump, and compare this steam pressure with the maximum and minimum values of the target pressure range after the load increase;

[0012] If this steam pressure is greater than or equal to the maximum value, adjust the opening of the steam small flow discharge valve to relieve pressure so that the steam pressure of the boiler is less than the maximum value;

[0013] If this steam pressure is less than or equal to the minimum value, increase the opening of the feed water regulating valve.

[0014] In some embodiments, the feed water regulating valve and the steam small flow discharge valve are adjusted again, including the following steps:

[0015] Calculate the control dead zone based on the target pressure range and the correction coefficient;

[0016] Periodically detect the steam pressure of the boiler and compare it with the control dead zone;

[0017] If this steam pressure is within the control dead zone, keep the opening of the feed water regulating valve unchanged;

[0018] If this steam pressure exceeds the control dead zone, adjust the opening of the feed water regulating valve again until the steam pressure of the boiler is within the target pressure range after the load increase.

[0019] In some embodiments, after it is determined that this steam pressure exceeds the control dead zone, the method further includes the following steps:

[0020] Judge whether this steam pressure exceeds the safety pressure threshold, and the safety pressure threshold is greater than the maximum value of the control dead zone;

[0021] If it exceeds the safety pressure threshold, adjust the openings of the steam small flow discharge valve and the feed water regulating valve to relieve pressure;

[0022] Otherwise, execute the step of adjusting the opening of the feed water regulating valve again until the steam pressure of the boiler is within the target pressure range after the load increase.

[0023] In some embodiments, if it exceeds the safety pressure threshold, adjust the openings of the steam small flow discharge valve and the feed water regulating valve to relieve pressure, which specifically includes the following steps:

[0024] Calculate the absolute value of the difference between the steam pressure and the safety pressure threshold, and compare it with the deviation threshold;

[0025] According to the comparison result, calculate the opening degrees of the small steam flow discharge valve and the feed water regulating valve, and perform regulation.

[0026] In some embodiments, the deviation thresholds include a first deviation threshold, a second deviation threshold, and a third deviation threshold, and the first deviation threshold < the second deviation threshold < the third deviation threshold;

[0027] According to the comparison result, calculating the opening degrees of the small steam flow discharge valve and the feed water regulating valve specifically includes the following steps:

[0028] If the absolute value of the difference between the steam pressure and the safety pressure threshold ≤ the first deviation threshold, keep the opening degrees of the small steam flow discharge valve and the feed water regulating valve unchanged;

[0029] If the first deviation threshold < the absolute value of the difference between the steam pressure and the safety pressure threshold ≤ the second deviation threshold, calculate the opening degree of the small steam flow discharge valve through proportional integral with a coefficient k1, and calculate the opening degree of the feed water regulating valve through proportional integral with a coefficient m1;

[0030] If the second deviation threshold < the absolute value of the difference between the steam pressure and the safety pressure threshold ≤ the third deviation threshold, calculate the opening degree of the small steam flow discharge valve through proportional integral with a coefficient k2, and calculate the opening degree of the feed water regulating valve through proportional integral with a coefficient m2;

[0031] If the absolute value of the difference between the steam pressure and the safety pressure threshold > the third deviation threshold, calculate the opening degree of the small steam flow discharge valve through proportional integral with a coefficient k3, and calculate the opening degree of the feed water regulating valve through proportional integral with a coefficient m3.

[0032] In some embodiments, before calculating the control dead zone based on the target pressure range and the correction coefficient, the steps further include: setting a preset range for the opening degree adjustment step of the feed water regulating valve.

[0033] In some embodiments, adjusting the steam inlet regulating valve on the turbine feed pump includes the following steps:

[0034] Based on the total steam flow required after the variable working conditions, calculate the total number of turbine feed pumps to be paralleled;

[0035] Based on the current pressure difference before and after the feed water regulating valve, calculate the operating speed of each turbine feed pump after paralleling;

[0036] Adjust the operating speed of the turbine feed pump by adjusting the opening degree of the steam inlet regulating valve on the turbine feed pump.

[0037] In a second aspect, a marine boiler multi-pump paralleling feed water control system is provided, which includes:

[0038] The first module is configured to: before the successful synchronization of the turbine boiler feed pumps, perform initial adjustment of the opening degrees of the feed water regulating valve and the steam small flow discharge valve;

[0039] The second module is configured to: obtain the steam pressure of the boiler after the successful synchronization of the turbine boiler feed pumps, and determine whether the steam pressure is within the target pressure range after the up - working condition;

[0040] If not, readjust the feed water regulating valve and the steam small flow discharge valve again, and adjust the steam admission regulating valve on the turbine boiler feed pump until it is within the target pressure range after the up - working condition.

[0041] In some embodiments, the first module is further configured to:

[0042] Obtain the steam pressure of the boiler before the successful synchronization of the turbine boiler feed pumps, and compare the steam pressure with the maximum and minimum values of the target pressure range after the up - working condition;

[0043] If the steam pressure is greater than or equal to the maximum value, adjust the opening degree of the steam small flow discharge valve to relieve pressure so that the steam pressure of the boiler is less than the maximum value;

[0044] If the steam pressure is less than or equal to the minimum value, increase the opening degree of the feed water regulating valve.

[0045] The beneficial effects brought by the technical solution provided in this application include:

[0046] This application provides a method and system for controlling the feed water during the parallel operation of multiple pumps in a marine boiler. During the operation of the marine boiler, before the successful synchronization of the turbine boiler feed pumps, the opening degrees of the feed water regulating valve and the steam small flow discharge valve are initially adjusted in advance. When the system changes its working condition, the steam pressure generated by the boiler is regulated and controlled through the feed water regulating valve and the steam small flow discharge, and the operating speed of the turbine boiler feed pump is regulated through the steam admission regulating valve, suppressing the "positive feedback" phenomenon, realizing the steady - state and variable - working - condition control of the device, preventing the oscillation of the steam pressure and steam superheat during the synchronization process, and shortening the synchronization process time. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0048] Figure 1 It is a flow chart of the method for controlling the feed water during the parallel operation of multiple pumps in a marine boiler provided in the embodiments of this application;

[0049] Figure 2This is the flow chart of the boiler feed water process system provided by the embodiments of the present application.

[0050] In the figure: 1. Turbine feed water pump; 2. Feed water regulating valve; 3. Steam small flow discharge valve; 4. Boiler. Specific embodiments

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0052] The embodiments of the present application provide a method and a system for controlling the parallel operation of multiple pumps for a marine boiler, which can solve the problem of difficult control when the steam pressure continuously rises in the related art.

[0053] In a first aspect, a method for controlling the parallel operation of multiple pumps for a marine boiler is provided, which includes:

[0054] 101: Before the successful parallel operation of the turbine feed water pump 1, perform an initial adjustment of the opening degrees of the feed water regulating valve 2 and the steam small flow discharge valve 3;

[0055] 102: Obtain the steam pressure of the boiler 4 after the successful parallel operation of the turbine feed water pump 1, and determine whether the steam pressure is within the target pressure range after the rising working condition;

[0056] 103: If not, adjust the feed water regulating valve 2 and the steam small flow discharge valve 3 again, and adjust the steam inlet regulating valve on the turbine feed water pump 1 until the steam pressure is within the target pressure range after the rising working condition.

[0057] In the present application, during the operation of the marine boiler 4, before the successful parallel operation of the turbine feed water pump 1, an initial adjustment of the opening degrees of the feed water regulating valve 2 and the steam small flow discharge valve 3 is performed in advance. When the system changes the working condition, the steam pressure generated by the boiler 4 is adjusted and controlled through the feed water regulating valve 2 and the steam small flow discharge valve 3, and the operating speed of the turbine feed water pump 1 is adjusted through the steam inlet regulating valve, suppressing the "positive feedback" phenomenon, realizing the steady-state and variable working condition control of the device, preventing the steam pressure and steam superheat degree from oscillating during the parallel operation process, and the parallel operation process takes too long.

[0058] It should be noted that: in the prior art, after the condensate enters the pipeline, it first passes through the turbine feed water pump 1 to reach the feed water regulating valve 2, and finally enters the marine boiler 4 through the feed water regulating valve 2 and becomes steam, and the steam generated by the marine boiler 4 is used as the power of the steam turbine water pump to drive the turbine feed water pump 1 to work.

[0059] When the system is in the up - load condition, the flow rate of the steam delivered by the marine boiler 4 to the turbine feed water pump 1 needs to increase. Therefore, it is necessary to increase the feed water volume of the turbine feed water pump 1 in the system. There are various ways to increase the feed water volume of the turbine feed water pump 1 in the system. For example, the rotational speed of the existing turbine feed water pump 1 in the system can be increased; a certain number of turbine feed water pumps 1 can also be added to the system, and the added turbine feed water pumps 1 are paralleled with the existing turbine feed water pumps 1. Here, the "existing" turbine feed water pump 1 refers to the turbine feed water pump 1 that has been working in the system for a period of time. However, when the maximum total feed water volume of the existing turbine feed water pumps 1 in the system is xt / h, and the minimum total feed water volume of the turbine feed water pumps 1 required after the system is in the up - load condition is yt / h, where y > x, at this time, a certain number of turbine feed water pumps 1 need to be added to the system, and the added turbine feed water pumps 1 are paralleled with the existing turbine feed water pumps 1.

[0060] In this application, only the situation of adding a certain number of turbine feed water pumps 1 to the system when the system is in the up - load condition is discussed. The number of added turbine feed water pumps 1 is determined according to the actual situation. For example: the total feed water volume of the existing turbine feed water pumps 1 in the system is Xt / h, and the feed water volume of a single turbine feed water pump 1 is Yt / h. After the system is in the up - load condition, the required feed water volume of the turbine feed water pumps 1 is X + Nt / h, where N < Y. At this time, only one turbine feed water pump 1 can be added and paralleled with the existing turbine feed water pumps 1; after the system is in the up - load condition, the required feed water volume of the turbine feed water pumps 1 is X + Nt / h, where 2Y > N > Y. At this time, another turbine feed water pump 1 can be added and paralleled with the existing turbine feed water pumps 1.

[0061] During the process from adding the turbine feed water pump 1 to the successful paralleling of this turbine feed water pump 1, the steam pressure generated by the marine boiler 4 and the feed water flow rate of the turbine feed water pump 1 have not changed significantly. At this time, the system issues a pre - judgment command to initially adjust the opening degrees of the feed water regulating valve 2 and the steam small - flow discharge valve 3 to prevent excessive oscillations in the steam pressure and steam superheat degree after successful paralleling.

[0062] The initial adjustment of the opening degrees of the feed water regulating valve 2 and the steam small - flow discharge valve 3 includes the following steps:

[0063] 201: Obtain the steam pressure of the boiler 4 before the successful paralleling of the turbine feed water pump 1, and compare this steam pressure with the maximum and minimum values of the target pressure range after the up - load condition.

[0064] 202: If this steam pressure is greater than or equal to the maximum value, adjust the opening degree of the steam small - flow discharge valve 3 for pressure relief so that the steam pressure of the boiler 4 is less than the maximum value.

[0065] 203: If this steam pressure is less than or equal to the minimum value, increase the opening degree of the feed water regulating valve 2.

[0066] The small steam flow discharge valve 3 can be connected to the marine boiler 4 to directly relieve the steam pressure generated by the marine boiler 4. Specifically, for each working condition, there is a corresponding target pressure range. For the convenience of description, the working conditions are divided into low working conditions, normal working conditions and high working conditions. The target pressure range corresponding to the low working condition is A - B MPa, the target pressure range corresponding to the normal working condition is C - D MPa, and the target pressure range corresponding to the high working condition is E - F MPa, where B < C and D < E.

[0067] For example, when it is necessary to raise the marine boiler 4 from the low working condition to the normal working condition, the target pressure range corresponding to the normal working condition is set as C - D MPa. When the steam pressure of the boiler 4 is 1 MPa before the successful paralleling of the turbine feed water pump 1, when I ≥ D, it is necessary to adjust the opening of the small steam flow discharge valve 3 to relieve the pressure until the steam pressure decreases; when I ≤ C, increase the opening of the feed water regulating valve 2.

[0068] Before the successful paralleling of the added turbine feed water pump 1, the steam pressure generated by the boiler 4 can be roughly adjusted through the feed water regulating valve 2 and the small steam flow discharge valve 3, which can stabilize the steam pressure in advance and realize the stable control of the system in the steady state and under variable working conditions.

[0069] After the successful paralleling of the turbine feed water pump 1, it is necessary to obtain the steam pressure of the boiler 4 and judge whether the steam pressure is within the target pressure range after the working condition is raised. At this time:

[0070] In the embodiment of the present application, the feed water regulating valve 2 and the small steam flow discharge valve 3 are adjusted again, including the following steps:

[0071] 301: Calculate the control dead zone based on the target pressure range and the correction coefficient;

[0072] 302: Periodically detect the steam pressure of the boiler 4 and compare it with the control dead zone;

[0073] 303: If the steam pressure is within the control dead zone, keep the opening of the feed water regulating valve 2 unchanged;

[0074] 304: If the steam pressure exceeds the control dead zone, adjust the opening of the feed water regulating valve 2 again until the steam pressure of the boiler 4 is within the target pressure range after the working condition is raised.

[0075] Specifically, correction factors for each working condition are set. Based on the correction factors for each working condition and the target pressure range for each working condition, the corresponding control dead zone for each working condition is calculated. When the actual steam pressure of the boiler 4 detected is within the control dead zone, the opening of the feed water regulating valve 2 remains unchanged. For example, the target pressure range corresponding to the normal working condition is C - D MPa, and the correction factor under the normal working condition is ΔT. Therefore, the corresponding control dead zone under the normal working condition is (C - ΔT) - (D + ΔT) MPa.

[0076] After the parallel operation of the turbine feed water pump 1 is successful, the steam pressure of the boiler 4 is periodically detected. Here, "periodically" means that the steam pressure of the boiler 4 is detected every certain period of time. The detection period is set as ts (such as 1 s). Before calculating the control dead zone based on the target pressure range and the correction factor, the said step further includes: setting a preset range for the opening adjustment step of the feed water regulating valve 2, that is, when the opening of the feed water regulating valve 2 is adjusted, within each period, the opening of the feed water regulating valve 2 can only be increased or decreased within the preset range of the adjustment step at a time. For example, when the opening adjustment step of the feed water regulating valve 2 is set to 3%, then the opening of the feed water regulating valve 2 can only be increased or decreased by 3% at a time.

[0077] After the parallel operation of the turbine feed water pump 1 is successful, if the steam pressure is within the control dead zone, the opening of the feed water regulating valve 2 remains unchanged; if the steam pressure exceeds the control dead zone, the opening of the feed water regulating valve 2 is adjusted again until the steam pressure of the boiler 4 is within the target pressure range after the rising working condition.

[0078] Further, after it is determined that the steam pressure exceeds the control dead zone, the said method further includes the following steps:

[0079] 401: Determine whether the steam pressure exceeds the safety pressure threshold, and the safety pressure threshold is greater than the maximum value of the control dead zone;

[0080] 402: If it exceeds the safety pressure threshold, adjust the openings of the steam small flow discharge valve 3 and the feed water regulating valve 2 to relieve the pressure;

[0081] 403: Otherwise, perform the operation of adjusting the opening of the feed water regulating valve 2 again until the steam pressure of the boiler 4 is within the target pressure range after the rising working condition.

[0082] After setting the control dead zone, it is also necessary to set the safety pressure threshold, where the safety pressure threshold is greater than the maximum value of the control dead zone. For example, if the control dead zone corresponding to normal operating conditions is (C - ΔT) - (D + ΔT) MPa, then the safety pressure threshold is greater than (D + ΔT) MPa, and the safety pressure threshold is set to (D + ΔT + ΔE) MPa. The purpose of setting the safety pressure threshold is to determine whether it is necessary to quickly relieve the steam pressure using the small steam flow discharge valve 3. When the newly started turbine feed water pump 1 successfully supplies water, the feed water flow increases, and the steam pressure will increase rapidly. At this time, quickly relieving the pressure through the small steam flow discharge valve 3 can stabilize the steam pressure and keep the steam pressure within the target range.

[0083] When the current steam pressure is between (C - ΔT) - (D + ΔT) MPa, the opening degrees of the feed water regulating valve 2 and the small steam flow discharge valve 3 remain unchanged; when the current steam pressure exceeds (C - ΔT) - (D + ΔT) MPa, if the steam pressure is lower than (C - ΔT) MPa, it is necessary to increase the opening degree of the feed water regulating valve 2, and if the steam pressure is between (D + ΔT) - (D + ΔT + ΔE) MPa, it is necessary to decrease the opening degree of the feed water regulating valve 2; when the current steam pressure is higher than (D + ΔT + ΔE) MPa, adjust the opening degrees of the small steam flow discharge valve 3 and the feed water regulating valve 2 to relieve the pressure.

[0084] Among them, if the safety pressure threshold is exceeded, adjust the opening degrees of the small steam flow discharge valve 3 and the feed water regulating valve 2 to relieve the pressure, which specifically includes the following steps:

[0085] 501: Calculate the absolute value of the difference between the steam pressure and the safety pressure threshold, and compare it with the deviation threshold;

[0086] 502: According to the comparison result, calculate the opening degrees of the small steam flow discharge valve 3 and the feed water regulating valve 2, and make adjustments.

[0087] Specifically, first, it is necessary to calculate the absolute value of the difference between the steam pressure and the safety pressure threshold. The safety pressure threshold is (D + ΔT + ΔE) MPa. At this time, it is necessary to calculate the difference between the steam pressure and (D + ΔT + ΔE) MPa, and compare its absolute value with the deviation threshold. Among them, the deviation threshold includes the first deviation threshold, the second deviation threshold, and the third deviation threshold, and the first deviation threshold < the second deviation threshold < the third deviation threshold. According to the comparison result, calculate the opening degrees of the small steam flow discharge valve 3 and the feed water regulating valve 2, which specifically includes the following steps:

[0088] If the absolute value of the difference between the steam pressure and the safety pressure threshold < the first deviation threshold, keep the opening degrees of the small steam flow discharge valve 3 and the feed water regulating valve 2 unchanged;

[0089] If the first deviation threshold ≤ the absolute value of the difference between the steam pressure and the safety pressure threshold < the second deviation threshold, the opening degree of the small steam flow discharge valve 3 is calculated by proportional-integral with the coefficient k1, and the opening degree of the feed water regulating valve 2 is calculated by proportional-integral with the coefficient m1. In this step, in the system, through the proportional-integral calculation formula, the opening degree of the small steam flow discharge valve 3 is calculated with the coefficient k1, and the opening degree of the small steam flow discharge valve 3 is adjusted to the calculated value, the opening degree of the feed water regulating valve 2 is calculated with the coefficient m1, and the opening degree of the feed water regulating valve 2 is adjusted to the calculated value;

[0090] If the second deviation threshold ≤ the absolute value of the difference between the steam pressure and the safety pressure threshold < the third deviation threshold, the opening degree of the small steam flow discharge valve 3 is calculated by proportional-integral with the coefficient k2, and the opening degree of the feed water regulating valve 2 is calculated by proportional-integral with the coefficient m2. In this step, in the system, through the proportional-integral calculation formula, the opening degree of the small steam flow discharge valve 3 is calculated with the coefficient k2, and the opening degree of the small steam flow discharge valve 3 is adjusted to the calculated value, the opening degree of the feed water regulating valve 2 is calculated with the coefficient m2, and the opening degree of the feed water regulating valve 2 is adjusted to the calculated value;

[0091] If the absolute value of the difference between the steam pressure and the safety pressure threshold ≥ the third deviation threshold, the opening degree of the small steam flow discharge valve 3 is calculated by proportional-integral with the coefficient k3, and the opening degree of the feed water regulating valve 2 is calculated by proportional-integral with the coefficient m3. In this step, in the system, through the proportional-integral calculation formula, the opening degree of the small steam flow discharge valve 3 is calculated with the coefficient k3, and the opening degree of the small steam flow discharge valve 3 is adjusted to the calculated value, the opening degree of the feed water regulating valve 2 is calculated with the coefficient m3, and the opening degree of the feed water regulating valve 2 is adjusted to the calculated value.

[0092] Preferably, in the embodiment of the present application, adjusting the steam inlet regulating valve on the turbine feed water pump 1 includes the following steps:

[0093] 601: Based on the total steam flow after the variable working conditions, calculate the total number of turbine feed water pumps 1 to be paralleled;

[0094] 602: Based on the pressure difference before and after the feed water regulating valve 2, calculate the operating speed of the paralleled turbine feed water pumps 1;

[0095] 603: Adjust the operating speed of the turbine feed water pump 1 by adjusting the opening degree of the steam inlet regulating valve of the turbine feed water pump 1

[0096] Wherein, each turbine feed water pump 1 is correspondingly provided with a feed water regulating valve 2 and a steam inlet regulating valve, and multiple feed water regulating valves 2 are arranged in parallel. When the opening degree of the steam inlet regulating valve is small, the steam intake is small, and at this time, the turbine feed water pump 1 is in a low-speed idle state; when the opening degree of the steam inlet regulating valve is large, the steam intake is large, and the rotational speed of the turbine feed water pump 1 is high.

[0097] Specifically, first, it is necessary to calculate the total number of turbine-driven boiler feed pumps 1 to be paralleled according to the total steam flow rate after the operating condition change; then determine the pressure difference before and after the feed water regulating valve 2 at this time, and determine the operating speed of the turbine-driven boiler feed pumps 1 after paralleling according to the pressure difference before and after the feed water regulating valve 2 at this time, so that the amount of condensed water delivered by the turbine-driven boiler feed pumps 1 to the marine boiler 4 can generate the total steam flow rate required after the operating condition change. After the operating speed of the turbine-driven boiler feed pumps 1 after paralleling is determined, the operating speed of the turbine-driven boiler feed pumps 1 is adjusted by adjusting the opening degree of the steam inlet regulating valve of the turbine-driven boiler feed pumps 1. According to the steam inlet regulating valve on the turbine-driven boiler feed pumps 1 tracking the pressure difference signal of the feed water regulating valve 2 to adjust the speed of the turbine-driven boiler feed pumps 1, so that the pressure difference before and after the feed water regulating valve 2 is maintained within the target pressure difference range.

[0098] In a second aspect, a multi-pump paralleling feed water control system for a marine boiler is provided, which includes: a first module and a second module. The first module is used for: before the successful paralleling of the turbine-driven boiler feed pumps 1, initially adjusting the opening degrees of the feed water regulating valve 2 and the small steam flow discharge valve 3; the second module is used for: obtaining the steam pressure of the boiler 4 after the successful paralleling of the turbine-driven boiler feed pumps 1, and determining whether the steam pressure is within the target pressure range after the rising operating condition; if not, adjusting the feed water regulating valve 2 and the small steam flow discharge valve 3 again, and adjusting the steam inlet regulating valve on the turbine-driven boiler feed pumps 1 until it is within the target pressure range after the rising operating condition.

[0099] In this application, during the operation of the marine boiler 4, before the successful paralleling of the turbine-driven boiler feed pumps 1, the opening degrees of the feed water regulating valve 2 and the small steam flow discharge valve 3 are initially adjusted in advance. When the system operating condition changes, the steam pressure generated by the boiler 4 is adjusted and controlled through the feed water regulating valve 2 and the small steam flow discharge valve 3, suppressing the "positive feedback" phenomenon, realizing the steady-state and variable operating condition control of the device, and preventing the steam pressure and steam superheat degree from oscillating during the paralleling process and the paralleling process time from being too long.

[0100] On the basis of the above embodiments, in this embodiment, the first module is further used for:

[0101] Obtaining the steam pressure of the boiler 4 before the successful paralleling of the turbine-driven boiler feed pumps 1, and comparing the steam pressure with the maximum value and the minimum value of the target pressure range after the rising operating condition;

[0102] If the steam pressure is greater than or equal to the maximum value, adjusting the opening degree of the small steam flow discharge valve 3 to relieve pressure so that the steam pressure of the boiler 4 is less than the maximum value;

[0103] If the steam pressure is less than or equal to the minimum value, increasing the opening degree of the feed water regulating valve 2.

[0104] The small steam flow discharge valve 3 can be connected to the marine boiler 4 to directly relieve the steam pressure generated by the marine boiler 4. Specifically, for each working condition, there is a corresponding target pressure range. For the sake of convenience of description, the working conditions are divided into low working condition, normal working condition and high working condition. The target pressure range corresponding to the low working condition is A - B MPa, the target pressure range corresponding to the normal working condition is C - D MPa, and the target pressure range corresponding to the high working condition is E - F MPa, where B < C and D < E.

[0105] For example, when it is necessary to raise the marine boiler 4 from the low working condition to the normal working condition, the target pressure range corresponding to the normal working condition is set as C - D MPa. When the steam pressure of the boiler 4 is I MPa before the parallel operation of the turbine feed water pump 1 is successful, when I ≥ D, it is necessary to adjust the opening of the small steam flow discharge valve 3 to relieve the pressure until the steam pressure decreases; when I ≤ C, increase the opening of the feed water regulating valve 2.

[0106] Before the additional turbine feed water pump 1 is successfully paralleled, the steam pressure generated by the boiler 4 can be roughly adjusted through the feed water regulating valve 2 and the small steam flow discharge valve 3, which can stabilize the steam pressure in advance and realize the stable control of the system under steady state and variable working conditions.

[0107] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0108] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0109] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A multi-pump parallel operation water supply control method for marine boilers, characterized in that, It includes: Before the successful paralleling of the turbine-driven feed water pump (1), initially adjust the opening degrees of the feed water regulating valve (2) and the steam small flow rate discharge valve (3); Obtain the steam pressure of the boiler (4) after the successful paralleling of the turbine-driven feed water pump (1), and determine whether the steam pressure is within the target pressure range after the rising operating condition; If not, adjust the feed water regulating valve (2) and the steam small flow rate discharge valve (3) again, and adjust the steam inlet regulating valve on the turbine-driven feed water pump (1) until the steam pressure is within the target pressure range after the rising operating condition.

2. The marine boiler multi-pump parallel operation feed water control method according to claim 1, characterized in that The initial adjustment of the opening degrees of the feed water regulating valve (2) and the steam small flow rate discharge valve (3) includes the following steps: Obtain the steam pressure of the boiler (4) before the successful paralleling of the turbine-driven feed water pump (1), and compare the steam pressure with the maximum and minimum values of the target pressure range after the rising operating condition; If the steam pressure is greater than or equal to the maximum value, adjust the opening degree of the steam small flow rate discharge valve (3) to relieve pressure so that the steam pressure of the boiler (4) is less than the maximum value; If the steam pressure is less than or equal to the minimum value, increase the opening degree of the feed water regulating valve (2).

3. The multi-pump parallel operation water supply control method for marine boilers according to claim 1, characterized in that The re-adjustment of the feed water regulating valve (2) and the steam small flow rate discharge valve (3) includes the following steps: Calculate the control dead zone based on the target pressure range and the correction coefficient; Periodically detect the steam pressure of the boiler (4) and compare it with the control dead zone; If the steam pressure is within the control dead zone, keep the opening degree of the feed water regulating valve (2) unchanged; If the steam pressure exceeds the control dead zone, re-adjust the opening degree of the feed water regulating valve (2) again until the steam pressure of the boiler (4) is within the target pressure range after the rising operating condition.

4. The multi-pump parallel operation water supply control method for marine boilers according to claim 3, characterized in that After it is determined that the steam pressure exceeds the control dead zone, the method further includes the following steps: Determine whether the steam pressure exceeds the safety pressure threshold, and the safety pressure threshold is greater than the maximum value of the control dead zone; If it exceeds the safety pressure threshold, adjust the opening degrees of the steam small flow rate discharge valve (3) and the feed water regulating valve (2) to relieve pressure; Otherwise, execute the step of re-adjusting the opening degree of the feed water regulating valve (2) again until the steam pressure of the boiler (4) is within the target pressure range after the rising operating condition.

5. The marine boiler multi-pump parallel feed water control method according to claim 4, characterized in that, If it exceeds the safety pressure threshold, adjust the opening degrees of the steam small flow rate discharge valve (3) and the feed water regulating valve (2) to relieve pressure, specifically including the following steps: Calculate the absolute value of the difference between the steam pressure and the safety pressure threshold, and compare it with the deviation threshold; According to the comparison result, calculate the opening degrees of the steam small flow rate discharge valve (3) and the feed water regulating valve (2), and make adjustments.

6. The multi-pump parallel operation water supply control method for marine boilers according to claim 5, characterized in that, The deviation threshold includes a first deviation threshold, a second deviation threshold, and a third deviation threshold, and the first deviation threshold < the second deviation threshold < the third deviation threshold; According to the comparison result, calculate the opening degrees of the steam small flow rate discharge valve (3) and the feed water regulating valve (2), specifically including the following steps: If the absolute value of the difference between the steam pressure and the safety pressure threshold < the first deviation threshold, keep the opening degrees of the steam small flow rate discharge valve (3) and the feed water regulating valve (2) unchanged; If the first deviation threshold ≤ the absolute value of the difference between the steam pressure and the safety pressure threshold < the second deviation threshold, the opening degree of the small steam flow discharge valve (3) is calculated by proportional integral with the coefficient k1, and the opening degree of the feed water regulating valve (2) is calculated by proportional integral with the coefficient m1; If the second deviation threshold ≤ the absolute value of the difference between the steam pressure and the safety pressure threshold < the third deviation threshold, the opening degree of the small steam flow discharge valve (3) is calculated by proportional integral with the coefficient k2, and the opening degree of the feed water regulating valve (2) is calculated by proportional integral with the coefficient m2; If the absolute value of the difference between the steam pressure and the safety pressure threshold ≥ the third deviation threshold, the opening degree of the small steam flow discharge valve (3) is calculated by proportional integral with the coefficient k3, and the opening degree of the feed water regulating valve (2) is calculated by proportional integral with the coefficient m3.

7. The multi-pump parallel operation water supply control method for marine boilers according to claim 3, characterized in that, Before calculating the control dead zone based on the target pressure range and the correction coefficient, the steps further include: setting a preset range for the opening degree adjustment step of the feed water regulating valve (2).

8. The marine boiler multi-pump parallel operation feed water control method according to claim 1, characterized in that, Adjusting the steam inlet regulating valve on the turbine feed water pump (1) includes the following steps: Based on the total steam flow required after the variable working condition, calculating the total number of turbine feed water pumps (1) to be paralleled; Based on the pressure difference before and after the current feed water regulating valve (2), calculating the operating speed of each turbine feed water pump (1) after paralleling; Adjusting the operating speed of the turbine feed water pump (1) by adjusting the opening degree of the steam inlet regulating valve on the turbine feed water pump (1).

9. A multi-pump parallel operation feed water control system for a marine boiler, characterized in that, It includes: The first module is used for: before the successful paralleling of the turbine feed water pumps (1), performing an initial adjustment of the opening degrees of the feed water regulating valve (2) and the small steam flow discharge valve (3); The second module is used for: obtaining the steam pressure of the boiler (4) after the successful paralleling of the turbine feed water pumps (1), and judging whether the steam pressure is within the target pressure range after the up - working condition; If not, adjusting the feed water regulating valve (2) and the small steam flow discharge valve (3) again, and adjusting the steam inlet regulating valve on the turbine feed water pump (1) until it is within the target pressure range after the up - working condition.

10. The multi-pump parallel operation feed water control system for marine boilers according to claim 9, characterized in that: The first module is also used for: Obtaining the steam pressure of the boiler (4) before the successful paralleling of the turbine feed water pumps (1), and comparing the steam pressure with the maximum and minimum values of the target pressure range after the up - working condition; If the steam pressure is greater than or equal to the maximum value, adjusting the opening degree of the small steam flow discharge valve (3) to relieve pressure so that the steam pressure of the boiler (4) is less than the maximum value; If the steam pressure is less than or equal to the minimum value, increasing the opening degree of the feed water regulating valve (2).

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