[0019] The embodiments of the present invention will be described in further detail below in conjunction with the description of the drawings, but this embodiment is not used to limit the present invention. Any similar structure and similar changes of the present invention should be included in the protection scope of the present invention.
[0020] An algorithm for determining effective desulfurization of coal-fired units in thermal power plants provided by an embodiment of the present invention includes the following steps:
[0021] 1) Judging the SO at the exit of the chimney 2 Whether the emission concentration is less than 400mg/m 3 Or 1200mg/m 3 (6% O2, dry flue gas), or calculated according to the following formula:
[0022] C so 2 , ch = V y , 2 × C so 2 , 2 + V y , 3 × C so 2 , 3 V y , 2 + V y , 3 ( mg / m 3 )
[0023] (Formula 1))
[0024] 2) Judge whether the desulfurization efficiency of the desulfurization island is greater than 95%;
[0025] 3). Judge whether the bypass baffle actuators (2~3) are in the state (opening, closing), and they must be in the closed state at the same time;
[0026] 4) Collect the flue gas flow and concentration at the entrance of the desulphurization island, the outlet of the desulphurization island and the bypass flue gas channel And the actual flue gas flow rate (Vy, j );
[0027] A. If any one of the conditions in 1) ~ 3) is not met, it can be determined that the desulfurization of the unit is invalid;
[0028] B. If the conditions in 1)~3) are met at the same time, the following calculation results are used to determine whether the desulfurization is effective:
[0029] a = Vy , j - Vy , 1 Vy , j ≠ 0 , Explain that part of the flue gas is discharged from the bypass channel, the principle is as follows:
[0030] I, a>10%, it can be judged that a large part of the flue gas enters the bypass channel and the desulfurization is invalid;
[0031] II, Vy, 3 ≤Vy, j ×(5%~8%) and a<10%, it can be considered that the flue gas entering the bypass meets the requirements, and it is judged that the desulfurization is effective;
[0032] III, Vy, 3Vy, j ×(5%~8%) and a<10%, it can be judged that desulfurization is invalid.
[0033] Such as figure 1 As shown, there are three core points in the effective desulfurization determination process for coal-fired units in thermal power plants. First, look at the opening and closing status of the damper actuator of the bypass flue gas passage of the coal-fired unit. If the flue gas damper is in the "divided" state, it means that most of the flue gas emitted by the coal-fired unit enters the chimney from the bypass channel. In this case, it can be said that the unit is in an undesulfurized state; secondly, when the bypass channel baffle is in the "closed" state, the flue gas discharged by the coal-fired unit enters the desulfurization island through inlet 1 (see figure 2 , Schematic diagram of desulfurization conditions), after desulfurization, the flue gas flow rate V at inlet 1 and outlet 2 collected by the desulfurization monitoring system respectively y，1 , V y，2 And smoke concentration Calculate the flue gas desulfurization efficiency. If the desulfurization efficiency is less than or equal to 95%, the desulfurization is determined to be invalid; third, the final SO2 emission concentration at the exit of the chimney must be less than 400mg/m 3 Or 1200mg/m 3 (If the unit is completed and put into operation or passed the environmental approval time is 1200mg/m3 before December 31, 1996; 400mg/m3 since January 1, 1997). Under the premise that the above three conditions are established, determine whether it is effective desulfurization according to the following steps:
[0034] 1) Collect inlet 1, outlet 2, bypass flue gas channel 3 everywhere (such as figure 2 Shown) flue gas flow and concentration; 2) using the unit coal consumption, coal quality, oxygen intake, unit output and boiler shape to calculate the flue gas flow (Vy, j ) And SO 2 Concentration; 3) Use the formula to calculate the value of a. In theory, the value of a should be 0, because the bypass channel baffles are all in the "closed" state, and the flue gas can only come out from the inlet "1", but in fact a may Not 0. Therefore, furthermore, if a≠0, it means that part of the flue gas is discharged from the bypass channel. The judgment principle is as follows: ①If a≥10%, it means that a large part of the flue gas is discharged from the bypass channel, and we judge it to be invalid for desulfurization. ②If a<10%, and the flue gas flow into the bypass channel V y，3 Accounted for the actual emissions Vy of coal-fired units, j Between 5% and 8%, or lower than this percentage, it means that there is little flue gas entering the bypass channel, and it is judged to be effective desulfurization.
[0035] In the process of algorithm determination, the determination interval of certain calculation quantities is based on the national SO2 emission standard for air pollution, and it is also limited based on the actual operating process of coal-fired units in thermal power plants, such as: SO2 emissions at the exit of the chimney Concentration is less than 400mg/m 3 Or 1200mg/m 3 , When the bypass flue gas flow accounts for a percentage of the total flow a≥10%, the judgment is invalid, and the judgment interval can be adjusted according to the actual situation. Methods similar and similar to this algorithm should be included in the scope of protection.
[0036] Further, the following examples illustrate the implementation process of the decision algorithm.
[0037] Example: The coal-fired unit 1 of a thermal power plant should produce a flue gas flow of 958.642m under normal circumstances 3 /kg, the bypass channel baffles are all in the "closed" state, the data collected by the desulfurization monitoring system is as follows: the flue gas flow at the entrance of the desulfurization island 1 is 852.381m 3/kh, SO2 concentration is 4565.485mg/m 3; The flue gas flow at exit 2 of the desulphurization island is 996.337m 3 /kh, SO2 concentration is 203.663mg/m 3; The flue gas flow at bypass channel 3 is 38.345m 3 /kh, SO2 concentration is 207.361mg/m 3; Desulfurization island desulfurization efficiency 95.555%. Try to judge whether the unit is effective desulfurization. If other conditions remain unchanged, the flue gas flow at the entrance of the desulphurization island 1 is 952.381m 3 /kh, what about the desulfurization situation of this unit?
[0038] Solution: According to the judgment algorithm, first judge whether the SO2 concentration at the chimney exit is less than 400mg/m 3 , Then put V y，2 =996.337m 3 /kh, C SO2，2 =203.663mg/m 3 , V y，3 = 38.345m 3 /kh, C SO2，3 =203.663mg/m 3 Substituting into formula (1),
[0039] SO2 concentration C SO2，ch =203.801mg/m 3 Less than 400mg/m 3 , Enter the next step of judgment;
[0040] From the question, the desulfurization efficiency of the desulfurization island is 95.555% greater than 95%;
[0041] From the question, all bypass baffle actuators are in the "close" state;
[0042] If the above three conditions are met, the desulfurization situation is judged by calculating the value of a:
[0043] If V y，1 =852.381m 3 /kh, then a = Vy , j - Vy , 1 Vy , j = 958.242 - 852.381 958.242 = 11.05 % , The value of a is greater than 10%, indicating that a large part of the flue gas enters the bypass channel, and the desulfurization is judged to be invalid;
[0044] If Vy, 1 =952.381m 3 /kh, then a = Vy , j - Vy , 1 Vy , j = 958.242 - 952.381 958.242 = 0.6 % , When a is less than 10%, by calculating Vy, 3 With Vy, j Relationship to determine the desulfurization situation, Vy , 3 Vy , j = 38.345 958.242 = 4 % , That is to satisfy Vy, 3 ≤Vy, j ×(5%-8%), it can be considered that the flue gas entering the bypass channel meets the requirements, and the desulfurization is determined to be effective.
[0045] The algorithm has the following explanations for the flue gas emissions of coal-fired units in thermal power plants:
[0046] 1) According to national emission requirements, as long as the SO at the chimney 2 The emission concentration can meet the requirements, so in the actual boiler operation, if the SO from the desulfurization tower 2 The emission concentration is much less than 400mg/m 3 Or 1200mg/m 3 (6% O2, dry flue gas), the bypass can be opened appropriately.
[0047] 2) As currently, there is no SO at the chimney 2 Emission concentration and bypass flue gas flow, so it is impossible to directly or indirectly calculate the SO at the chimney 2 Regarding the emission concentration, although the unit has been put into the desulfurization system, there may be a short circuit when the bypass flue gas is opened. Therefore, it is necessary to be able to determine whether the amount of flue gas entering the desulfurization island is normal, that is, whether most of the flue gas has entered the desulfurization island.
[0048] 3) For coal-fired boilers, under the same pressure level, the efficiency of the unit is not much different. The amount of flue gas generated is mainly related to the unit load, so the actual value of the flue gas entering the desulfurization island should not deviate far from the load condition Calculated value.
