Precautions for sulfuric acid production in winter

Those using PVC pipes in the system should be careful to avoid cracking due to cold； Pay attention to the maintenance of acid storage equipment such as acid tanks and circulation tanks, and repair any issues found promptly.

It is necessary for everyone to review the properties of sulfuric acid, especially its crystallization temperature. Carefully check for any ‘dead zones’ of sulfuric acid in the production process and take necessary insulation measures.

It’s around minus 10 degrees here in winter, and driving is no problem under normal conditions. I’m worried that an accident might occur if the car is parked for a long time during winter. When temperatures are low in winter, lower the concentration of the absorption cycle acid before parking to prevent sulfuric acid from crystallizing. We have encountered accidents where, during parking, the acid pump was operating normally, but the outlet of the absorption tower froze up, causing acid to flow from the gas pipeline into the heat exchanger! When installing long-distance acid transport pipelines, the slope should be carefully considered to prevent acid from accumulating in the pipes; of course, it’s best not to produce 98% acid during winter! But since there is customer demand, we have to produce it; in winter, we even produce 105% acid. The 98% acid tanks and the 105% acid tanks are all placed indoors and insulated with steam coils.

Sulfuric acid with a high concentration should be kept at a temperature of 60 degrees Celsius using warm water; too high a steam temperature will increase its corrosiveness

It’s not just acid pipelines; our company also has 105% sulfuric acid, which is insulated using steam. In addition, the liquid sulfur trioxide unit is located in a insulated room with a temperature controlled at 38 degrees, and the pipes for transporting liquid sulfur trioxide are insulated using hot water jackets. Additionally, insulation for the on-site level gauges and instrument pipes is also very important. During the Spring Festival in 2005, the instrument pipes of the on-site level gauge and transmitter in the deaerator froze up, resulting in no level readings available either at the deaerator site or in the DCS, which almost led to a shutdown of the plant.

It rarely drops below 0°C here, but in recent days the temperature has remained around -2°C. No problems have been detected so far in the sulfuric acid system; however, in the steam system, the pressure tubes of the instruments have frozen, resulting in inaccurate readings on those instruments. This is dangerous for the boiler. Temporary insulation measures have been put in place now, but it seems that our anti-freezing measures are not sufficient!

In winter, be sure to insulate acidic pipelines properly

During winter, proper measures for the \"four protections\" must be taken in sulfuric acid production.

1. In winter, due to the low ambient temperature, the temperature of the acid also decreases accordingly. Generally speaking, the ideal anodic protection potential for 98% sulfuric acid in winter is between 0 and 400 mV. As long as the control potential remains within the range of 200–400 mV, the monitoring potential stays within the range of 0–400 mV, and the voltage and current are within normal limits, a good level of protection can be achieved. 2. It should be noted that once it is found that the control values of 98% acid during winter fall within the aforementioned range, immediate contact should be established with the after-sales service staff of the manufacturer, so that the manufacturer’s technical personnel can make a judgment based on the parameter data. 3. 98% acid (freezing point: -4°C), 96% acid (freezing point: -13°C), 93% acid (freezing point: -33°C)

I learned a lot today; thank you all.

In winter, the temperature of the circulating water is lower; it is possible to reduce its flow rate slightly to save energy. Another thing to keep in mind is preventing the backup equipment from freezing; it’s advisable to keep the cooling water for the backup equipment running, at a somewhat reduced level if necessary. This post was last edited by in the blink of an eye on 2008-1-22 14:38]

Production of 1.98 acid must be halted; 93 and 105 acids are to be produced by mixing them on the spot. 2. For pipe-cooled systems, the water temperature is adjusted according to specific conditions in order to save energy consumption (such as the water flow rate for cooling towers and pumps). 3. Anti-freezing measures for the equipment (cranking the pump when it is in operation, removing acid from the pipelines, etc.). 4. Boiler water treatment and anti-freezing of the water supply system.

For sulfuric acid production using pyrite, with slurry feeding, it is necessary to stock up on raw materials in advance during winter, to prevent the moisture in these materials from freezing and causing difficulties in preparing the slurry as well as uneven composition of the mixture, which is detrimental to stable production

I’m sorry if I seem stupid; could you please explain what a slurry feeder is? :handshake

Pardon my ignorance! ! :handshake

At our company, the temperature is currently around minus 5 degrees Celsius. Due to power outages and power restrictions, sulfuric acid pipelines (98%), branch water pipes, steam pipelines, as well as ash slurry pipelines have all been frozen by condensation water, which has created many difficulties and problems for production.

The material is mixed with water to form a slurry and then fed into the furnace; this method has been widely used in the desulfurization of gold concentrate in recent years.

When producing sulfuric acid in winter, attention is mainly paid to its crystallization temperature to facilitate storage and transportation. Below are the crystallization temperatures for several common concentrations of sulfuric acid: 93% sulfuric acid –27.0 degrees; 100% free acid +10.371 degrees; 98.5% sulfuric acid +1.8 degrees; 110% free acid –1.5 degrees; 92% sulfuric acid –17.5 degrees; 105% free acid +5.4 degrees; 94% sulfuric acid –31.9 degrees; 95% sulfuric acid –22.6 degrees; 98% sulfuric acid –0.7 degrees; 99% sulfuric acid +4.5 degrees; 99.5% sulfuric acid +7.5 degrees. Therefore, in cold regions such as northern China, sulfuric acid should be produced primarily in the 93% concentration.

Winter is coming soon, so it’s quite meaningful to look at old posts. Here are a few points: 1. The climate is relatively dry in winter, and winds are strong as well; therefore, all work sites need to take proper fire prevention measures. Especially in the sulfur melting section, when sulfur melting is not taking place (when the sulfur melter or forklift operator is on break), appropriate measures must be taken to actively prevent fires. 2. Pay attention to preventing freezing of fire protection pipelines, water pipelines, steam pipelines, and equipment (including drainage pipelines such as vent pipes and safety valves); keep those pipelines flowing continuously, and ensure that water is completely drained from lower points in cases where it is not needed. 3. Ensure proper insulation of the instruments. Many pressure and temperature sensors in the field and at remote locations are prone to freezing in winter; please ensure proper insulation and the use of electric heating tapes. 4. For the production of 98 acid, pay attention to the acid discharge or insulation work in pipelines that are not used regularly, such as the acid discharge pipes, the pipes for adding acid to large tanks, and areas in front of the acid discharge valves on large tanks. Devices equipped with DWHS should have their heating systems tested earlier, to ensure that heating works properly in areas such as the sampling pipelines and level gauges. 5. Any leaks or spills at the site should be addressed in advance, as ice formation on the ground during winter poses a significant risk to operational safety.

I want to know the freezing point of sodium sulfite solutions with concentrations of 5% and 10%. Could anyone please help me out?