Integrated comprehensive adjustment method for pulverized coal boiler based on prevention and control of high-temperature corrosion of water wall

An adjustment method for operation of a pulverized coal boiler, the method comprising:

• S1, mounting a sampling pipe on a water-cooled wall of a boiler during a period of stopping operation of the boiler, wherein the sampling pipe is configured to obtain reducing atmosphere of installation location thereof;
• S2, operating the boiler at a first load point, a second load point, and a third load point, respectively, to obtain test data, wherein a value of the first load point is smaller than a value of the second load point, and a value of the second load point is smaller than the value of the third load point;
• and
• wherein the test data comprises the reducing atmosphere at the sampling pipe, a concentration of NOx at a denitrification inlet of the boiler, and a boiler thermal efficiency;
• S3, controlling air velocity deviation between pulverized coal pipes of a coal mill of the boiler to be less than or equal to a first preset threshold value, and controlling pulverized quantity deviation between two pulverized coal pipes on one side of the coal mill to be less than or equal to a second preset threshold value;
• and controlling fineness of pulverized coal of the coal mill to be within a preset range;
• S4, carrying out a single-factor test, wherein single-factor variables thereof are air distribution mode, opening degree of perimeter air, primary air velocity, operation oxygen content, and sulfur content in coal;
• the single-factor test comprising the following steps:
• S4-1, keeping the opening degree of perimeter air, the primary air velocity, the operation oxygen content, and the sulfur content in coal unchanged, adjusting the air distribution mode, and testing the reducing atmosphere at the sampling pipe, the boiler thermal efficiency, and the concentration of NOx at the denitrification inlet, respectively;
• S4-2, keeping the air distribution mode, the primary air velocity, the operation oxygen content, and the sulfur content in coal unchanged, adjusting the opening degree of perimeter air, and testing the reducing atmosphere at the sampling pipe, the boiler thermal efficiency, and the concentration of NOx at the denitrification inlet, respectively;
• S4-3, keeping the air distribution mode, the opening degree of perimeter air, the operation oxygen content, and the sulfur content in coal unchanged, adjusting the primary air velocity, and testing the reducing atmosphere at the sampling pipe, the boiler thermal efficiency, and the concentration of NOx at the denitrification inlet, respectively;
• S4-4, keeping the air distribution mode, the opening degree of perimeter air, the primary air velocity, and the sulfur content in coal unchanged, adjusting the operation oxygen content, and testing the reducing atmosphere at the sampling pipe, the boiler thermal efficiency, and the concentration of NOx at the denitrification inlet, respectively;
• S4-5, keeping the air distribution mode, the opening degree of perimeter air, the primary air velocity, and the operation oxygen content unchanged, adjusting the sulfur content in coal, and testing the reducing atmosphere at the sampling pipe, the boiler thermal efficiency, and the concentration of NOx at the denitrification inlet, respectively;
• S5, comparing influence levels of each single-factor variable on the reducing atmosphere at the sampling pipe, boiler thermal efficiency, and concentration of NOx at the denitrification inlet according to test results of steps S41 to S45;
• S6, operating the boiler at the first load point, the second load point, and the third load point, respectively, and adjusting ammonia flows of branch pipes of each ammonia spraying grid according to NOx concentration distribution at an outlet cross-section of an SCR reactor of the boiler, to cause an ammonia spraying amount of each branch pipe of ammonia spraying grid to match the NOx concentration distribution;
• S7, operating the boiler at the third load point and determining a maximum concentration value of NOx at the denitrification inlet that a denitrification system of the boiler can withstand without ammonia escape exceeding a third preset threshold;
• and
• S8, determining a reducing atmosphere at the sampling pipe and a boiler thermal efficiency according to the maximum concentration value of NOx at the denitrification inlet that the denitrification system can withstand, and determining a boiler optimized operation mode according to a comparison result in step S5, comprising:
• a single-factor variable with greater influence in the comparison result were prioritized for adjustment.