Denitration control method according to load of gas-steam combined cycle gas turbine

Abstract

The invention discloses a denitration control method according to the load of a gas-steam combined cycle gas turbine, which comprises the following steps of: 1, obtaining a first output value by taking the load of the gas turbine as a function value of a parameter, namely the value of NOX contained in unit flue gas under the load; 2, calculating a difference value between the first output value and an NOX set value to obtain a second output value; 3, obtaining a third output value by taking the load of the gas turbine and the environment temperature as function values of the two parameters; 4, obtaining a fourth output value by a function taking the second output value and the third output value as parameters; 5, subtracting the ammonia water flow from the fourth output value to obtain a fifth output value; and step 6, enabling the fifth output value to pass through a main regulator to obtain an ammonia water regulating valve instruction. According to the method for adjusting the flow of the ammonia water according to the load of the gas turbine, the accuracy of the spraying amount of the ammonia water is scientifically improved, and the ammonia water can be effectively wasted while NOX discharged by the gas turbine is accurately controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas-steam combined cycle units, and in particular relates to a denitration control method according to the load of a gas-steam combined cycle combustion engine. Background Art

[0002] The country is paying more and more attention to environmental protection, and the pollutant emission indicators of power production enterprises have become increasingly stringent in recent years. For gas-fired generators, the emission of nitrogen oxides in flue gas is generally required to be controlled below 30mg / m3. In some areas, the emission performance of nitrogen oxides must be lower than 0.100g / kWh, which corresponds to the emission of nitrogen oxides in flue gas below 20mg / Nm3. It is very important to accurately control the spraying of ammonia water under higher control requirements.

[0003] At present, the denitrification system used in gas-steam combined cycle units does not have the function of automatically adjusting the ammonia spraying amount in advance according to the change of gas turbine load under automatic control. Under manual control, there is inevitably a lag in adjustment, which often leads to excessive spraying of ammonia and waste, or insufficient spraying of ammonia and causes the emission of nitrogen oxides in the flue gas to exceed the limit. In addition, manual adjustment requires more energy and manpower. Summary of the invention

[0004] The object of the present invention is to provide a denitration control method according to the load of a gas-steam combined cycle combustion engine, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a denitration control method according to the load of a gas-steam combined cycle combustion engine, characterized in that it comprises the following steps: Step 1: Calculate the first output value based on the function value of the gas turbine load as a parameter, that is, the NO content per unit flue gas under this load. X value; Step 2: Calculate the first output value and NO X The difference of the set values ​​produces a second output value; Step 3: derive a third output value based on the engine load and the ambient temperature as a function of two parameters, namely, the flue gas flow rate emitted by the engine at this load and ambient temperature; Step 4: Obtain a fourth output value, that is, the amount of NO reduced as required, by a function using the second output value and the third output value as parameters. X The required ammonia flow rate is obtained based on the value and denitrification efficiency; Step 5: Subtract the ammonia flow rate from the fourth output value to obtain a fifth output value; Step 6: The fifth output value is passed through the main regulator to obtain the ammonia regulating valve instruction; Preferably, in step 4, the second output value and the third output value are used as a function of parameters: F(a)=a×b×c; Wherein a is the second output value, b is the third output value, and c is the denitrification efficiency coefficient. Preferably, the ambient temperature in step 3 is the ambient temperature detected by the combustion engine; NO X The set value is NO after denitrification X The desired emission value, the gas turbine load is the gas-steam combined cycle gas turbine load value.

[0006] Preferably, the first output value in step 2 is the NO contained in the unit flue gas under different loads. X value; the second output value is the NO contained in the unit flue gas X Value and NO X The difference in the desired emission value, that is, the NO that needs to be reduced per unit of flue gas emission X value.

[0007] Preferably, the third output value in step three is the amount of flue gas emitted by the gas turbine calculated based on the gas turbine load and ambient temperature.

[0008] Preferably, the fourth output value in step 4 is the NO required to be reduced per unit flue gas emission. X The required theoretical ammonia flow rate is calculated based on the value and the flue gas discharged by the gas turbine, and the actual required ammonia flow rate is calculated based on the efficiency compensation coefficient. The main regulator is the main regulator of the cascade regulation system.

[0009] Preferably, the ammonia regulating valve instruction in step six includes an increase opening instruction, a decrease opening instruction, and an unchanged opening instruction, and the increase opening instruction is to correspondingly increase the opening of the original ammonia regulating valve; the increase opening instruction is provided with an adjustment opening instruction of 1%-100%, and the increase opening instruction increases gradually by 1%-5%.

[0010] Preferably, the opening increase instruction is provided with an adjustment opening instruction of 1%-100%, and the opening increase instruction increases gradually by 1%-5%.

[0011] Preferably, the opening reduction instruction is to correspondingly reduce the opening of the original ammonia regulating valve, and the opening reduction instruction is provided with an adjustment opening instruction of 1%-100%, and the opening reduction instruction is gradually reduced by 1%-5%.

[0012] Preferably, the unchanged opening instruction is to maintain the original opening of the ammonia water regulating valve.

[0013] Compared with the prior art, the technical effects and advantages of the present invention are as follows: the denitrification control method according to the load of the gas-steam combined cycle combustion engine can accurately control the usage of denitrification ammonia water, reduce ammonia escape, reduce energy consumption and material consumption, save costs, improve denitrification efficiency and ensure that emissions meet standards, avoid the invariance of manual adjustment, and solve the problem of adjustment delay commonly existing in automatic denitrification systems, optimize operation and maintenance management, and protect the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a denitration control flow chart of the present invention.

[0015] In the figure: 1, first output value; 2, second output value; 3, third output value; 4, fourth output value; 5, fifth output value. DETAILED DESCRIPTION The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] See also Figure 1 The present invention provides a technical solution: a denitration control method according to the load of a gas-steam combined cycle combustion engine, comprising the following steps: Step 1: Calculate the first output value 1 based on the function value of the gas turbine load as a parameter, that is, the NO content per unit flue gas under this load. X value; Step 2: Calculate the first output value 1 and NO X The difference of the set values ​​produces the second output value 2; Step 3: derive a third output value 3 based on the engine load and the ambient temperature as a function of two parameters, that is, the flue gas flow rate emitted by the engine at this load and ambient temperature; Step 4: The fourth output value 4 is obtained by using the function with the second output value 2 and the third output value 3 as parameters, that is, the NO reduced as required. X The required ammonia flow rate is obtained based on the value and denitrification efficiency; Step 5: Subtract the ammonia flow rate from the fourth output value 4 to obtain a fifth output value 5; Step 6: The fifth output value 5 is passed through the main regulator to obtain the ammonia regulating valve instruction; In step 4, the second output value 2 and the third output value 3 are used as a function of parameters: F(a)=a×b×c; Wherein a is the second output value 2, b is the third output value 3, and c is the denitrification efficiency coefficient.

[0017] Considered NO X The ratio of reaction with ammonia water, the concentration of ammonia water, the efficiency of the reaction and other influencing factors; by considering a variety of factors, the required ammonia water flow rate can be accurately obtained, so that the precise opening of the corresponding ammonia water regulating valve can be calculated, so as to achieve efficient control of NO X emissions. In step 3, the ambient temperature is the ambient temperature detected by the engine; NO X The set value is NO after denitrification X The desired emission value, the gas turbine load is the gas-steam combined cycle gas turbine load value.

[0018] The first output value 1 in step 2 is the NO content of unit flue gas under different loads. X The second output value 2 is the NO contained in the unit flue gas. X Value and NO X The difference in the desired emission value, that is, the NO that needs to be reduced per unit of flue gas emission X value.

[0019] The third output value 3 in step three is the amount of flue gas emitted by the combustion engine calculated based on the combustion engine load and the ambient temperature.

[0020] The fourth output value 4 in step 4 is the NO that needs to be reduced according to the unit flue gas emission. X The required theoretical ammonia flow rate is calculated based on the value and the flue gas discharged by the gas turbine, and the actual required ammonia flow rate is calculated based on the efficiency compensation coefficient. The main regulator is the main regulator of the cascade regulation system.

[0021] According to the ammonia regulating valve instruction in step six, including the increase opening instruction, the decrease opening instruction, and the unchanged opening instruction, the ammonia regulating valve instruction setting can accurately control the opening of the ammonia regulating valve according to the difference between the actual required ammonia flow rate and the current ammonia flow rate entering the denitrification system; when the current ammonia flow rate is not enough to remove NO at the reactor inlet, X When fully restored, the ammonia regulating valve instruction will control the ammonia regulating valve to open wider; When the current ammonia flow rate is sufficient to reduce the NO X If there is still redundancy, the ammonia regulating valve instruction will control the ammonia regulating valve to close; when the difference between the actual required ammonia flow rate and the current ammonia flow rate entering the denitrification system is less than the set value, the ammonia regulating valve instruction will control the ammonia regulating valve to keep the current opening unchanged.

[0022] Through this setting, the opening of the ammonia regulating valve can be accurately controlled to adjust the ammonia flow rate, thereby achieving efficient control of NOX emissions and avoiding waste of ammonia.

[0023] The command to increase the opening is to increase the opening of the original ammonia regulating valve accordingly; the command to increase the opening is provided with a 1%-100% regulating opening command, and the command to increase the opening is gradually increased by 1%-5%.

[0024] The opening increase command is set to 1%-100% of the adjustment opening command, and the opening increase command is gradually increased by 1%-5% The opening reduction instruction is to reduce the original ammonia regulating valve opening accordingly. The opening reduction instruction is provided with a 1%-100% adjustment opening instruction. The opening reduction instruction is gradually reduced by 1%-5%. The unchanged opening instruction is to maintain the original ammonia regulating valve opening.

[0025] By setting the above-mentioned ammonia regulating valve instruction, the ammonia flow rate can be controlled very accurately under the condition of stable changes in the opening of the ammonia regulating valve, which is beneficial to the long-term safe operation of the equipment and improves the reliability of the equipment.

[0026] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0027] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be realized by any existing technology.

Claims

1. A denitration control method according to the load of a gas-steam combined cycle combustion engine, characterized in that: The following steps are involved: Step 1: Calculate the first output value based on the function value of the gas turbine load as a parameter, that is, the NO content per unit flue gas under this load. X value; Step 2: Calculate the first output value and NO X The difference of the set values ​​produces a second output value; Step 3: derive a third output value based on the engine load and the ambient temperature as a function of two parameters, namely, the flue gas flow rate emitted by the engine at this load and ambient temperature; Step 4: Obtain a fourth output value, that is, the amount of NO reduced as required, by a function using the second output value and the third output value as parameters. X The required ammonia flow rate is obtained based on the value and denitrification efficiency; Step 5: Subtract the ammonia flow rate from the fourth output value to obtain a fifth output value; Step 6: The fifth output value is passed through the main regulator to obtain the ammonia regulating valve instruction.

2. A denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 1, characterized in that: In step 4, the second output value and the third output value are used as a function of parameters: F(a)=a×b×c; Wherein a is the second output value, b is the third output value, and c is the denitrification efficiency coefficient.

3. The denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 1, characterized in that: The ambient temperature in step 3 is the ambient temperature detected by the combustion engine; NO X The set value is NO after denitrification X The desired emission value, the gas turbine load is the gas-steam combined cycle gas turbine load value.

4. The denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 1, characterized in that: The first output value in step 2 is the NO contained in the unit flue gas under different loads. X The second output value is the NO contained in the unit flue gas. X Value and NO X The difference in the desired emission value, that is, the NO that needs to be reduced per unit of flue gas emission X value.

5. The denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 1, characterized in that: The third output value in step three is the amount of flue gas emitted by the combustion engine calculated based on the combustion engine load and the ambient temperature.

6. A denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 2, characterized in that: The fourth output value in step 4 is the NO required to be reduced according to the unit flue gas emission. X The required theoretical ammonia flow rate is calculated based on the value and the flue gas discharged by the gas turbine, and the actual required ammonia flow rate is calculated based on the efficiency compensation coefficient. The main regulator is the main regulator of the cascade regulation system.

7. The denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 1, characterized in that: According to the ammonia regulating valve instruction in step six, there are an increase opening instruction, a decrease opening instruction, and an unchanged opening instruction. The increase opening instruction is to increase the original ammonia regulating valve opening accordingly; the increase opening instruction is provided with an adjustment opening instruction of 1%-100%, and the increase opening instruction is gradually increased by 1%-5%.

8. A denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 7, characterized in that: The opening increase instruction is provided with an adjustment opening instruction of 1%-100%, and the opening increase instruction is gradually increased by 1%-5%.

9. A denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 8, characterized in that: The opening reduction instruction is to reduce the opening of the original ammonia regulating valve accordingly. The opening reduction instruction is provided with an adjustment opening instruction of 1%-100%, and the opening reduction instruction is gradually reduced by 1%-5%.

10. A denitration control method according to the load of a gas-steam combined cycle combustion engine according to claim 9, characterized in that: The unchanged opening instruction is to maintain the original opening of the ammonia water regulating valve.

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