Flushing frequency of plate heat exchanger for acid production from smelting flue gas
Thread Content
:'(Our acid production system is designed to produce acid from smelting flue gas, with a capacity of 60 KT/A. It was put into operation in August last year; after about six months of operation, it was found that the purification plate heat exchangers were severely clogged. Upon consulting the installation company, it was stated that this is a common phenomenon in acid production using smelting flue gas. I would like to ask the experts on this forum whether such a situation is normal?) How long does it take for you to arrange the cleaning of plate heat exchangers? Thank you!
We also have a smelting and acid production system; if the electrostatic precipitator is operating properly, it needs to be cleaned every 3-4 months. This applies mainly to the acid sludge on the acid side. If the water quality on that side is poor, cleaning may be necessary every 1-2 months. If the electrostatic precipitator isn’t effective at removing dust, cleaning might be required even within a month. In case of blockages caused by scale, scale-inhibiting products can be added to the circulating water side.
For a new system during startup, some congestion is normal, but for an old system, such congestion is highly abnormal.
It is normal for blockages to occur at first. As for the specific frequency of cleaning, it is necessary to analyze it based on the dust collection situation and the specific conditions of the heat exchanger; one should also consider the timing available in one’s own company. Checks can be carried out each time the plant is temporarily shut down, so as to determine a specific schedule
It is necessary to check the water hardness. When the acid side is blocked, more wastewater needs to be discharged. It’s probably because of blockages on the water side more often.
There are no major issues when the electrostatic precipitator is used normally; the main problem is that at the beginning of operation, the temperature is not high enough, resulting in a large amount of soot being present. The main issue here is severe acid corrosion and blockage; when it was disassembled for cleaning, there was also a certain amount of dirt on the water side, which is due to the poor filtering efficiency of the circulating water!
The efficiency of electrostatic dust collectors is indeed very important. However, if the problems associated with electrostatic dust collectors cannot be resolved over time, it is possible to consider using dilute acid filters; these filters can recover dust, clarify the acid, and also extend the service life of the plate exchangers – achieving three benefits at once.
If there is a blockage on the water side, then install a water-side filter, which can remove sediment as well as other debris such as packing
There has never been any blockage on the water-change side of our plant’s heat exchangers. The acid side is usually cleaned once a year; this is mainly related to the type of minerals used in the furnace as well as the operation of the electrostatic precipitator. It is particularly necessary to carry out cleaning before summer arrives.
If it’s on the acid side: the efficiency of electrostatic dust collectors is indeed very important. However, if the problems associated with electrostatic dust collectors cannot be resolved over time, considering the use of dilute acid filters could be an option – these filters can recover dust, clarify the acid, and also extend the service life of the plate exchangers. If it is on the water side, the acid circuit and water circuit of the plate exchanger can be swapped depending on the situation.
We came up with a solution: every 2 months, during downtime, swap the acid side and the water side (this is planned in the pipeline layout, with some pipes being custom-made), and conduct a thorough cleaning during the annual overhaul