“ Continued the previous article "sulfur acid waste heat boiler fire tube leakage cause analysis and treatment (Part 1)" ”

First, the solution:

1. During the operation of the waste heat boiler, due to long-term high-load operation, frequent startup and shutdown of the device, obvious temperature changes in the high-temperature section and other problems, alternating load is formed, which inevitably causes various defects in its pressure parts [1]. If these defects are not found early and measures are taken to eliminate them, they will continue to deteriorate during use and lead to serious accidents. Therefore, in the use of boiler management, it is necessary to regularly inspect, it is best to use handheld X-ray flaw detection, regularly ask third-party professionals to repair and deal with, timely eliminate hidden dangers, prevent problems, improve the safety situation of equipment, and provide protection for the safe operation of the boiler.

2. Liquid sulfur is atomized by a sulfur-gun and then burned in a sulfur-burning furnace. If the atomization effect of the sulfur-gun is not good, it will cause vulcanization corrosion to the fire tube. Therefore, in the selection of the equipment specifications of the sulfonate gun, the welds of the gun body should be selected with fewer welds, and X-ray non-destructive testing should be carried out at the weld seam of the steam insulation clamp sleeve of the nozzle to prevent the steam leakage of the weld seam and nozzle of the sulfonate gun.

3. The material of the fire tube is made of high-quality materials, and it is strictly tested to eliminate the birth defects of the material. If all the pipes on the heating surface are produced by imported pipes or special steel mills, 100% ultrasonic detection and 100% eddy current detection should be carried out on them. All the pipes on the heating surface should be argon arc welding or argon arc welding as the base, and the flaw detection should be carried out after welding, so as to minimize the manufacturing defects; The tube and tube plate of fire tube boiler shall be welded by argon arc, and 100% magnetic particle inspection shall be carried out after welding [2].

4. Select good quality safety accessories, especially safety valves and water level gauges, and regularly check whether they work normally. Control the drum water level, pay special attention to not lower than the set minimum water level, in order to remove safety hazards; During the annual middle repair and the biennial overhaul, the drum and the front smoke box must be entered to check the corrosion of the end face. The cleaning and caulking operations in the sulfur burning furnace are essential maintenance items.

Two, preventive measures:

(1) Control water quality and steam quality in strict accordance with the requirements of GB/T 12145 "Water vapor Quality of thermal generating units and steam power Equipment", and find out the cause immediately if there is a failure to ensure that the boiler water vapor quality reaches the standard in real time [3];

(2) The boiler is separately equipped with a set of blowdown expansion vessel, and the blowdown pipe 20 m away is lower than the bottom of the shell I and shell II, and is laid along the ground to a separate blowdown well, and the pressure monitoring device is added to the blowdown pipe to ensure the blowdown rate and discharge amount.

(3) Regular endoscopy, timely removal of scale and water slag, dredging all kinds of pipelines, strictly prevent clogging;

(4) Regularly determine the hardness value (HB) of shell I and shell II tube plates, and carry out metallography detection of shell tube plates combined with system overhaul to monitor whether the tube plates are overheated and the material is deteriorated;

(5) Periodically analyze the silica content in the feed water, and control the silica content in the boiler feed water at a low proportion level;

(6) Increase the frequency of analysis of pharmaceutical content, and the purity of < 98% is strictly prohibited;

(7) Add a secondary overtemperature alarm for flue gas temperature at the exit of the waste heat boiler, with a high alarm value of 380℃ and an ultra-high alarm value of 390℃.