Analysis of fouling, water carryover, and overpressure in evaporative hot water tower fillers

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Low-pressure gray water, low-temperature shift condensate, and black water from the gasification system undergo heat exchange in an evaporative hot water tower to recover heat. The flash vapor, at around 150°C, comes into direct contact with the material in the packing layer for heat exchange, thereby becoming high-temperature hot water that is used in a washing tower to clean the crude water gas. Fluctuations in water quality, changes in coal type, and extended operation cycles can lead to scaling and ash accumulation on the packing when the water quality is substandard. This reduces the flow area through the packing layer, resulting in incomplete heat exchange and an increase in the pressure difference between the upper and lower sections. In severe cases, this pressure exceeds the design limit, forcing the use of safety valve bypasses for adjustment, which poses a risk to the safe and stable operation of the system. When the packing layer becomes severely clogged, the gas flow velocity increases, resulting in the entrainment of foam. This can damage the defoaming screen and carry the packing along with water into the pipes, thereby blocking the heat exchanger. It may also cause valves to get stuck or water to enter the flare line. In severe cases, it is very difficult to regulate the liquid level in the high-temperature hot water tank, which makes it inconvenient to adjust the balance in the water supply system. In extreme situations, this can lead to a disruption in the cooling water supply to the quenching ring and damage to the downcomers.