System and method for regulating seawater desulfurization variable-frequency circulating water pump on the basis of fire coal sulfur content

Abstract

A system and method for regulating a seawater desulfurization variable-frequency circulating water pump on the basis of a fire coal sulfur content, the method comprising: acquiring a fire coal sulfur content, the amount of coal fed into a boiler, seawater alkalinity and a seawater pH value, so as to obtain a required circulating water flow rate and a corresponding circulating water pump frequency; obtaining the required circulating water flow rate by means of a unit load, a seawater temperature and a seawater tide level, so as to obtain another corresponding circulating water pump frequency; and finally, calculating the optimal circulating water pump frequency by means of common coupling. The power consumption rates of units are reduced, and safe, energy-saving and environment-friendly operation of the units are ensured.

Description

Regulation system and method for variable frequency circulating water pump for seawater desulfurization based on coal sulfur content

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on July 20, 2023, with application number 202310896178.8 and invention name “Regulation system and method for variable frequency circulating water pump for seawater desulfurization based on coal-fired sulfur content”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of seawater desulfurization, and relates to a regulating system and method for a variable frequency circulating water pump for seawater desulfurization based on the sulfur content of coal. Background Art

[0004] Some power plants located on the coast use seawater desulfurization technology. The circulating water passes through the condenser and enters the aeration tank, where it mixes with the boiler flue gas. The alkaline substances in the seawater react with the sulfur oxides in the flue gas to remove the sulfur from the flue gas.

[0005] For units equipped with variable-frequency circulating water pumps that don't use seawater desulfurization, the circulating water flow rate is determined by seawater temperature, unit load, and tidal fluctuations. To ensure desulfurization effectiveness, units using seawater desulfurization typically use an excess of circulating water. This results in the variable-frequency circulating water pump operating at a high frequency year-round, increasing its power consumption and, consequently, unit energy consumption. Therefore, optimizing the circulating water pump frequency to minimize unit power consumption is crucial.

[0006] Summary of the Invention

[0007] The purpose of this application is to solve the technical problem in the prior art that in order to ensure the desulfurization effect, excessive circulating water is used, which causes the variable frequency circulating water pump to often run at a high frequency, increases the power consumption rate of the circulating water pump, and leads to increased energy consumption of the unit, and provides a regulation system and method for a variable frequency circulating water pump for seawater desulfurization based on coal sulfur content.

[0008] To achieve the above objectives, this application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a method for regulating a variable frequency circulating water pump for seawater desulfurization based on coal sulfur content, comprising the following steps:

[0010] Step 1: Obtain the unit load, seawater temperature and seawater tide level to obtain the first circulating water pump frequency D4;

[0011] Step 2: Obtain the sulfur content of the coal, the amount of coal fed into the furnace, the alkalinity of seawater, and the pH value of seawater to obtain the frequency D5 of the second circulating water pump;

[0012] Step 3: Select the maximum value between the first circulating water pump frequency D4 and the second circulating water pump frequency D5 as the final circulating water pump frequency D6; input the final circulating water pump frequency D6 into the variable frequency circulating water pump.

[0013] The optional improvements to the above method are:

[0014] The step 1 includes: inputting the flow signal D1 based on the load and water temperature and the minimum head signal D2 into the first frequency processor 11 to obtain the first circulating water pump frequency D4, and the calculation process is as follows: D4 = Q' / k

[0015] Wherein, Q′ is the maximum output flow rate corresponding to the flow signal D1 based on load and water temperature and the minimum head signal D2 in the circulating water pump HQ curve, and k is the flow coefficient.

[0016] The generation of the flow signal D1 based on load and water temperature includes: inputting the seawater temperature signal S1 and the unit load signal S2 into a first flow processor 8 for calculating the seawater flow, and obtaining the flow signal D1 based on load and water temperature through a cold end optimization test.

[0017] The seawater temperature signal S1 is measured by a temperature measuring device 4 .

[0018] The unit load signal S2 is generated by the DEH system 5 .

[0019] The generation of the minimum head signal D2 includes: inputting the seawater tide signal S3 into the head processor 9 for calculating the minimum head signal to ensure the operation of the circulating water pump to obtain the minimum head signal D2. The calculation process is as follows: H = H1 - H2

[0020] Among them, H1 is the elevation of the condenser top, H2 is the actual tide level, and H is the minimum head.

[0021] The seawater tide level signal S3 is measured by a tide level measuring device 6 .

[0022] The step 2 includes: inputting the seawater flow signal D3 required for desulfurization into the second frequency processor 12 to obtain the second circulating water pump frequency D5, and the calculation process is as follows: D5 = Q / k

[0023] Where Q is the seawater flow rate required for desulfurization, and k is the flow coefficient.

[0024] The generation of the seawater flow rate signal D3 required for desulfurization includes: inputting the coal sulfur content signal S4 output by the coal quality testing system 7, the real-time coal input signal S5 output by the DCS system 14, and the seawater alkalinity signal S6 and seawater pH value signal S7 output by the seawater quality measuring device 15 into the second flow processor 10 to obtain the seawater flow rate signal D3 required for desulfurization. The calculation process is as follows:

[0025] in, is the sulfur dioxide content at the desulfurization inlet, K is the proportion of sulfur in the coal oxidized to sulfur dioxide after combustion, Bg is the real-time coal quantity fed into the furnace, q4 is the heat loss of mechanical combustion, and the boiler design value or test value is used. S ar The sulfur content of coal, is the desulfurization efficiency in the circulating fluidized bed boiler;

[0026] Among them, Q is the seawater flow rate required for desulfurization, is the sulfur dioxide content at the desulfurization inlet, For desulfurization efficiency, the design value or experimental value is adopted, A is the total alkalinity of seawater, and pH2 is the pH value of seawater.

[0027] In the second aspect, the present application provides a regulation system for a seawater desulfurization variable frequency circulating water pump based on coal sulfur content, including a tide level measuring device 6, which is installed at the seawater forebay 1; the output end of the tide level measuring device 6 is electrically connected to the input end of the lift processor 9, and the output end of the lift processor 9 is electrically connected to the input end of the first frequency processor 11; the temperature measuring device 4 is connected to the seawater forebay, and the output end of the temperature measuring device 4 is respectively connected to the first flow processor 8 and the input end of the variable frequency circulating water pump 2; the output end of the DEH system 5 is electrically connected to the input end of the first flow processor 8, and the output end of the first flow processor 8 is electrically connected to the The input end of the first frequency processor 11 is electrically connected, and the output end of the first frequency processor 11 is electrically connected to the input end of the third frequency processor 13; the input end of the second flow processor 10 is electrically connected to the output ends of the coal quality testing system 7, the DCS system 14 and the seawater quality measuring device 15 respectively; the output end of the second flow processor 10 is electrically connected to the input end of the second frequency processor 12; the output end of the second frequency processor 12 is electrically connected to the input end of the third frequency processor 13; the output end of the third frequency processor 13 is electrically connected to the input end of the variable frequency circulating water pump 2, and the output end of the variable frequency circulating water pump 2 is connected to the condenser 3.

[0028] Compared with the prior art, this application has the following beneficial effects:

[0029] The present application uses real-time coal sulfur content data to obtain the required circulating water flow rate and a corresponding circulating water pump frequency based on the coal sulfur content, the amount of coal fed into the furnace, the alkalinity of seawater, and the pH value of seawater; the required circulating water flow rate and another corresponding circulating water pump frequency are obtained through the unit load, seawater temperature, and seawater tide level; and finally, the optimal circulating water pump frequency is obtained through joint coupling calculation; the use of excessive circulating water is avoided, the power consumption rate of the unit is reduced, and the safe, energy-saving, and environmentally friendly operation of the unit is ensured.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0032] FIG1 is a flow chart of the present application method;

[0033] FIG2 is a structural diagram of the system of the present application;

[0034] Among them: 1-seawater forebay; 2-variable frequency circulating water pump; 3-condenser; 4-temperature measuring device; 5-DEH system (Digital Electro-Hydraulic, digital electro-hydraulic control system); 6-tide level measuring device; 7-coal quality testing system; 8-first flow processor; 9-lift processor; 10-second flow processor; 11-first frequency processor; 12-second frequency processor; 13-third frequency processor; 14-DCS system (Distributed Control System) System, distributed control system); 15-seawater quality measuring device; S1-seawater temperature signal; S2-unit load signal; S3-seawater tide level signal; S4-coal sulfur content signal; S5-real-time coal input signal; S6-seawater alkalinity signal; S7-seawater pH value signal; D1-flow signal based on load and water temperature; D2-minimum head signal; D3-seawater flow signal required for desulfurization; D4-first circulating water pump frequency; D5-second circulating water pump frequency; D6-final circulating water pump frequency. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0038] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the product of the invention is usually placed when in use. This is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0039] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of this application, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in this application based on specific circumstances.

[0041] The present application is described in further detail below with reference to the accompanying drawings:

[0042] Example 1:

[0043] Referring to FIG1 , the present application discloses a method for regulating a variable frequency circulating water pump for seawater desulfurization based on coal sulfur content, comprising the following steps:

[0044] 1) Obtain the unit load, seawater temperature and seawater tide level to obtain the first circulating water pump frequency D4;

[0045] The temperature measuring device 4 measures the seawater temperature signal S1, and the DEH system 5 outputs the unit load signal S2. The seawater temperature signal S1 and the unit load signal S2 are input into the first flow processor 8 for calculating the seawater flow rate. The flow signal D1 based on the load and water temperature is obtained through the cold end optimization test;

[0046] The seawater tide level signal S3 is measured by the tide level measuring device 6, and the seawater tide level signal S3 is input into the head processor 9 used to calculate the minimum head signal to ensure the operation of the circulating water pump to obtain the minimum head signal D2. The calculation process is as follows: H = H1 - H2

[0047] Among them, H1 is the elevation of the condenser top, H2 is the actual tide level, and H is the minimum head.

[0048] The flow signal D1 based on the load and water temperature and the minimum head signal D2 are input into the first frequency processor 11 for calculating the optimal operating frequency of the circulating water pump to obtain the first circulating water pump frequency D4.

[0049] The calculation process is as follows:

[0050] D4=Q′ / k

[0051] Wherein, D4 is the frequency of the first circulating water pump, Q′ is the maximum output flow corresponding to the flow signal D1 based on load and water temperature and the minimum head signal D2 in the circulating water pump HQ curve, and k is the flow coefficient.

[0052] 2) Obtain the sulfur content of the coal, the amount of coal fed into the furnace, the alkalinity of seawater, and the pH value of seawater to obtain the frequency D5 of the second circulating water pump;

[0053] The coal sulfur content signal S4 output by the coal quality testing system 7, the real-time coal quantity signal S5 output by the DCS system 14, and the seawater alkalinity signal S6 and seawater pH value signal S7 output by the seawater quality measuring device 15 are input to the second flow processor 10 to obtain the seawater flow signal D3 required for desulfurization. The calculation process is as follows:

[0054] in, is the sulfur dioxide content at the desulfurization inlet, K is the proportion of sulfur in the coal oxidized to sulfur dioxide after combustion, and B g is the real-time coal quantity fed into the furnace, q4 is the heat loss after mechanical combustion, and the boiler design value or test value is adopted. S ar The sulfur content of coal, is the desulfurization efficiency in the circulating fluidized bed boiler;

[0055] Among them, Q is the seawater flow rate required for desulfurization, is the sulfur dioxide content at the desulfurization inlet, For desulfurization efficiency, the design value or experimental value is adopted, A is the total alkalinity of seawater, and pH2 is the pH value of seawater.

[0056] The seawater flow signal D3 required for desulfurization is input into the second frequency processor 12 to obtain the second circulating water pump frequency D5. The calculation process is as follows: D5 = Q / k

[0057] Among them, D5 is the frequency of the second circulating water pump, Q is the seawater flow rate required for desulfurization, and k is the flow coefficient.

[0058] 3) Selecting the maximum value between the first circulating water pump frequency D4 and the second circulating water pump frequency D5 as the final circulating water pump frequency D6; inputting the final circulating water pump frequency D6 into the variable frequency circulating water pump;

[0059] Example 2:

[0060] Referring to Figure 2, the present application discloses a regulating system for a variable frequency circulating water pump for seawater desulfurization based on coal sulfur content, wherein a tide level measuring device 6 is installed at a seawater forebay 1; an output end of the tide level measuring device 6 is electrically connected to an input end of a lift processor 9, and an output end of the lift processor 9 is electrically connected to an input end of a first frequency processor 11; a temperature measuring device 4 is connected to the seawater forebay, and an output end of the temperature measuring device 4 is respectively connected to an input end of a first flow processor 8 and a variable frequency circulating water pump 2; an output end of a DEH system 5 is electrically connected to an input end of a first flow processor 8, and an output end of the first flow processor 8 is electrically connected to an input end of a first frequency processor The input end of the first frequency processor 11 is electrically connected to the input end of the third frequency processor 13; the input end of the second flow processor 10 is electrically connected to the output ends of the coal quality testing system 7, the DCS system 14 and the seawater quality measuring device 15 respectively; the output end of the second flow processor 10 is electrically connected to the input end of the second frequency processor 12; the output end of the second frequency processor 12 is electrically connected to the input end of the third frequency processor 13; the output end of the third frequency processor 13 is electrically connected to the input end of the variable frequency circulating water pump 2, and the output end of the variable frequency circulating water pump 2 is connected to the condenser 3.

[0061] Here's how this application works:

[0062] The temperature measuring device 4 measures the seawater temperature signal S1, and the DEH system 5 outputs the unit load signal S2. The seawater temperature signal S1 and the unit load signal S2 are jointly fed into the first flow processor 8 to obtain a flow signal D1 based on the load and water temperature. The tide level measuring device 6 obtains the seawater tide level signal S3, which is fed into the head processor 9 to obtain a minimum head signal D2. The flow signal D1 and the minimum head signal D2 based on the load and water temperature are fed into the first frequency processor 11 to obtain the first circulating water pump frequency D4.

[0063] The coal quality testing system 7 outputs a coal sulfur content signal S4, the DCS system 14 outputs a real-time coal input signal S5, and the seawater quality measuring device 15 outputs a seawater alkalinity signal S6 and a seawater pH value signal S7. The coal sulfur content signal S4, the real-time coal input signal S5, the seawater alkalinity signal S6, and the seawater pH value signal S7 enter the second flow processor 10 to obtain the seawater flow signal D3 required for desulfurization. The seawater flow signal D3 required for desulfurization enters the second frequency processor 12 to obtain the second circulating water pump frequency D5.

[0064] The first circulating water pump frequency D4 and the second circulating water pump frequency D5 enter the third frequency processor 13 together, and the highest frequency value is selected as the final circulating water pump frequency D6. The final circulating water pump frequency D6 signal enters the variable frequency circulating water pump, and finally controls the circulating water pump frequency.

[0065] The above are only preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection created by the present application.

Claims

1. A method for regulating a variable frequency circulating water pump for seawater desulfurization based on coal sulfur content, characterized in that: The following steps are involved: Step 1: Obtain the unit load, seawater temperature and seawater tide level to obtain the first circulating water pump frequency (D4); Step 2: Obtain the sulfur content of the coal, the amount of coal fed into the furnace, the alkalinity of seawater and the pH value of seawater to obtain the frequency of the second circulating water pump (D5); Step 3: Select the maximum value of the first circulating water pump frequency (D4) and the second circulating water pump frequency (D5) as the final circulating water pump frequency (D6); input the final circulating water pump frequency (D6) into the variable frequency circulating water pump.

2. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 1 is characterized in that: The step 1 includes: inputting the flow signal (D1) based on the load and water temperature and the minimum head signal (D2) into the first frequency processor (11) to obtain the first circulating water pump frequency (D4), and the calculation process is as follows: D4 = Q' / k Wherein, Q′ is the maximum value of the output flow corresponding to the flow signal (D1) based on load and water temperature and the minimum head signal (D2) in the HQ curve of the circulating water pump, and k is the flow coefficient.

3. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 2 is characterized in that: The generation of the flow signal (D1) based on the load and water temperature comprises: inputting the seawater temperature signal (S1) and the unit load signal (S2) into a first flow processor (8) for calculating the seawater flow, and obtaining the flow signal (D1) based on the load and water temperature through a cold end optimization test.

4. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 3 is characterized in that: The seawater temperature signal (S1) is measured by a temperature measuring device (4).

5. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 3 is characterized in that: The unit load signal (S2) is generated by the DEH system (5).

6. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 2 is characterized in that: The generation of the minimum head signal (D2) includes: inputting the seawater tide signal (S3) into a head processor (9) for calculating the minimum head signal to ensure the operation of the circulating water pump to obtain the minimum head signal (D2), and the calculation process is as follows: H = H1-H2 Among them, H1 is the elevation of the top of the condenser, H2 is the actual tide level, and H is the minimum head.

7. The method for regulating the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 6, characterized in that: The seawater tide level signal (S3) is measured by a tide level measuring device (6).

8. The method for adjusting the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 1 is characterized in that: The step 2 includes: inputting the seawater flow signal (D3) required for desulfurization into the second frequency processor (12) to obtain the second circulating water pump frequency (D5), and the calculation process is as follows: D5 = Q / k Wherein, Q is the seawater flow rate required for desulfurization, and k is the flow coefficient.

9. The method for regulating the frequency conversion circulating water pump for seawater desulfurization based on coal-fired sulfur content according to claim 8, characterized in that: The generation of the seawater flow rate signal (D3) required for desulfurization includes: inputting the coal sulfur content signal (S4) output by the coal quality testing system (7), the real-time coal quantity signal (S5) output by the DCS system (14), and the seawater alkalinity signal (S6) and the seawater pH value signal (S7) output by the seawater quality measuring device (15) into the second flow processor (10) to obtain the seawater flow rate signal (D3) required for desulfurization. The calculation process is as follows: in, is the sulfur dioxide content at the desulfurization inlet, K is the proportion of sulfur in the coal oxidized to sulfur dioxide after combustion, and B g is the real-time amount of coal fed into the furnace, q4 is the heat loss of mechanical combustion, using the boiler design value or test value, S ar The sulfur content of coal, is the desulfurization efficiency in the circulating fluidized bed boiler; Where Q is the seawater flow rate required for desulfurization, is the sulfur dioxide content at the desulfurization inlet, is the desulfurization efficiency, the design value or experimental value is adopted, A is the total alkalinity of seawater, and pH2 is the pH value of seawater.

10. The regulation system of the frequency conversion circulating water pump for seawater desulfurization based on coal sulfur content is characterized by: The invention comprises a tide level measuring device (6), which is installed at a seawater forebay (1); the output end of the tide level measuring device (6) is electrically connected to the input end of a lift processor (9), and the output end of the lift processor (9) is electrically connected to the input end of a first frequency processor (11); a temperature measuring device (4) is connected to the seawater forebay, and the output end of the temperature measuring device (4) is respectively connected to the input end of a first flow processor (8) and a variable frequency circulating water pump (2); the output end of a DEH system (5) is electrically connected to the input end of the first flow processor (8), and the output end of the first flow processor (8) is electrically connected to the input end of a first frequency processor (11). The output end of the first frequency processor (11) is electrically connected to the input end of the third frequency processor (13); the input end of the second flow processor (10) is electrically connected to the output ends of the coal quality testing system (7), the DCS system (14) and the seawater quality measuring device (15) respectively; the output end of the second flow processor (10) is electrically connected to the input end of the second frequency processor (12); the output end of the second frequency processor (12) is electrically connected to the input end of the third frequency processor (13); the output end of the third frequency processor (13) is electrically connected to the input end of the variable frequency circulating water pump (2), and the output end of the variable frequency circulating water pump (2) is connected to the condenser (3).

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