1.1 Dust generated by upstream flue gas
The dust brought by the upstream flue gas will adhere to the surface of the heat exchange element to varying degrees when entering the GGH. After online high-pressure water and steam blowing cleaning, the vast majority of loosely adhered ash and scale are peeled off and removed. A small amount of unremoved ash and scale adhere more firmly due to high-pressure flushing water and wet flue gas from the absorption tower. When GGH is transferred to the original flue gas (high temperature side), harder dirt is formed at high temperatures. This cycle accumulates over time, and the amount of dirt accumulates more and more, affecting the operation of the system and making it difficult to handle.
1.2 Slurry brought by wet flue gas
The wet flue gas from the absorption tower brings slurry. Due to the difficulty of removing the slurry from wet flue gas and its accumulation on the defogger, the channel of the defogger becomes narrower. In this way, the flow rate of wet flue gas increases, and the amount of slurry carried by saturated wet flue gas increases. When these saturated wet flue gases pass through the high-temperature GGH heat storage plate, the slurry moisture is evaporated, and the residual solids adhere to the heat storage plate, forming extremely hard dirt.
1.3 Absorption tower slurry level too high
1.4 Composition of dirt
2 Cleaning process
2.1 Comes with high-pressure water and steam blowing equipment for online cleaning.
Generally, GGH users have designed and installed online high-pressure water and steam blowing devices. According to the operational requirements of GGH, high-pressure flushing water and steam blowing should be started at regular intervals for each shift. This type of cleaning and descaling is very limited, and can only remove most of the accumulated dust each time. A small amount of dust will still adhere to the surface of the heat exchange element and gradually accumulate. This online blowing can effectively extend the usage time of GGH.
2. 2 Stop GGH for high-pressure water flushing
After running GGH for a period of time, the online flushing no longer meets the operational requirements. When the blockage is severe, the load of the unit not only fails to meet the process indicators, but also causes unsafe accidents such as surge and current increase of the booster fan, resulting in tripping. Emergency cleaning can be carried out by stopping the desulfurization operation, bypassing the flue gas, closing the inlet and outlet flue doors of the GGH system without any flue gas circulation, and opening the GGH maintenance manhole for online high-pressure water flushing. The cleaning time is usually around 60 hours to clear the gaps of GGH thermal storage components. To prevent damage to the enamel of GGH heat storage plates caused by high-pressure water, it is advisable to use a flushing water pressure of around 45 MPa. Rinse the upper and lower parts of GGH one by one.
2.3 Shutdown without disassembling high-pressure water flushing+chemical spray cleaning. After several high-pressure water flushes, the accumulated dirt on the heat storage element is difficult to remove solely with high-pressure water. Depending on the specific scaling condition and user maintenance period, if the scaling is not very serious and the maintenance period does not exceed 15 days, the relatively ideal cleaning process can use "chemical+high-pressure water flushing", which first uses chemical to soften the dirt, and then uses high-pressure water flushing. When using this cleaning process, the first step is to have a certain amount of time, about 10 days, and secondly, the chemicals should not corrode enamel, carbon steel, and anti-corrosion coatings.
