What chemical products require refrigeration in the production process?

The production of chemical products may require many steps of reaction (especially in the pharmaceutical industry), some processes reflect the need to control the temperature, the need to heat the hot water jacket, the need to cool down the use of cold water jacket, a reflection kettle outer layer has a jacket, the jacket has a number of pipe circuits, generally there are cold and hot water pipes.

Hot water is generally supplied by the thermal power center of the plant (boiler room, power plant, etc.)**;

Cold water is generally supplied by refrigeration stations**. CO2, ammonia, nitrogen, are all refrigerants, not refrigerant carriers. The general refrigerant is freon, or liquid ammonia (non-ammonia); The most commonly used refrigerant in the chemical plant is brine, and the temperature can be controlled to -10 10 degrees.

There is also a kind of refrigerant is silicone oil, silicone oil has a variety of different types, according to different models, the temperature of the cooling is also different, generally can reach minus 6, 70 degrees. You can check it out for details. However, silicone oil is expensive and consumes high energy, so it is generally used less in chemical plants as a refrigerant at very low temperatures.

In fact, the most commonly used is salt water, which is cheap and works very well. I remember when we used -8 degrees of brine in the production of chemical intermediates, it could cause a layer of frost on the outside of the brine pipes in the summer, hehe

It is inevitable that there will be heat in the production process, and some chemicals will decompose or denature when heated, such as anhydrous ethanol will reach the ignition point at 50-60 degrees.

You can use liquid CO2, ammonia, nitrogen (more wasteful) can be used. Or simply connect the tube from the cold storage to get some cold air in.

In the chemical production process, which links need to be refrigerated, and what is the refrigerant selected?

In the process of chemical production, what are the refrigerants used in those links that need to be made to make celery and chilled? Hello dear, as long as it involves the gas-liquid phase separation device rock burial, it should all need low-temperature refrigeration! At present, ammonia or propylene are the most common refrigerants, and isopentane seems to be rare.

I hope I can help you.

1) Cooling (condensation) The main difference between cooling and condensation is whether the phase of the cooled material changes, if the phase change occurs, it becomes condensation, otherwise, if there is no phase change but the temperature decreases, it is cooling. The cooling (coagulation) method can be divided into direct cooling method and indirect cooling method. In chemical production, when the material is cooled above the atmospheric temperature, air or circulating water can be used as the cooling medium; The cooling temperature is above 15, and groundwater can be used; When the cooling temperature is 0 5, you can use frozen brine.

According to the form and structure of the heat transfer surface of the cooling (condensation) equipment, it can be divided into tubular cooler (condenser), plate cooler (condenser) and mixed cooler (condenser). The key points of hazard control in the cooling process are as follows: The cooling equipment and coolant should be correctly selected according to the temperature, pressure, physical and chemical properties of the cooled material and the required cooling process conditions.

Water should not be used as a coolant for the cooling of water-resistant materials, and special measures should be taken when necessary. Strict attention should be paid to the tightness of the cooling equipment to prevent the material from entering the coolant or the coolant from entering the material. During the cooling operation, the cooling medium can not be interrupted, otherwise it will cause heat accumulation, make the reaction abnormal, increase the temperature and pressure of the system, and cause disasters.

Before starting, the fluid in the condenser should be removed first; When starting, the cooling medium should be introduced first, and then the high-temperature material should be introduced; When stopping, the material should be stopped first, and then the cooling system should be stopped. In order to ensure the safe emptying of non-condensable combustible gases, nitrogen can be filled for protection. Materials with high freezing point are easy to become viscous or solidified after cooling, so pay attention to controlling the temperature during cooling to prevent the material from collapsing and jamming the agitator or blocking the equipment and pipelines.

2) RefrigerationIn the process of industrial production, the liquefaction of steam and gas, the low-temperature separation of certain components, and the transportation and storage of certain items, etc., often need to reduce the material to a lower temperature than water or surrounding air, which is called freezing or refrigeration. Generally speaking, any frozen range within -100 is called freezing; Whereas, at -100 -200 or less, it is called deep freezing or simply cryogenic. Refrigerants commonly used in industry are ammonia and freon.

In petrochemical production, petroleum cracking products ethylene and propylene are commonly used as cryogenic separation refrigerants. The key points of hazard control in the freezing process are as follows: For the compressor, condenser, evaporator and pipeline system of the refrigeration system, attention should be paid to the pressure resistance level and air tightness to prevent cracks and leakage in the equipment and pipelines.

In addition, the inspection and maintenance of pressure gauges, safety valves, etc. should be strengthened. For the low-temperature part, attention should be paid to the selection of low-temperature materials to prevent low-temperature embrittlement. When an accident or emergency shutdown occurs in the refrigeration system, attention should be paid to the emptying and disposal of the frozen materials.

For ammonia compressors, non-sparking electrical equipment should be used; The compressor should be lubricated oil that does not freeze at low temperature and does not react chemically with the refrigerant, and the oil separator should be located outdoors. Pay attention to the corrosion protection of the cold carrier brine system.