How to make nitrogen in industry, how to make nitrogen in life

Industrial nitrogen production is to use the liquid air separation method to separate oxygen and nitrogen by using the different boiling points of each air.

Although nitrogen is more abundant in the atmosphere than oxygen, because of its inactive nature, people only know nitrogen after understanding oxygen. However, it was discovered before oxygen. Shortly after the discovery of carbonic acid by the British chemist Braque in 1755, he discovered that the carbonic acid produced by burning charcoal in a glass cover still has a large amount of air left even after being absorbed by caustic potassium solution.

Later, his pupil D. Rutherford continued experiments with animals, placing rats in closed glass enclosures until their deaths, and found that the volume of air in the enclosures had decreased.1 10If the remaining gas is absorbed with a caustic potassium solution, the volume of 1 11 will continue to be reduced.

There are three types of industrial-scale nitrogen production: cryogenic air separation nitrogen production, pressure swing adsorption nitrogen production, and membrane separation nitrogen production.

1. Cryogenic air separation nitrogen production.

It is a traditional air separation technology, has a history of more than 90 years, it is characterized by large gas production, high nitrogen purity of the product, can be directly applied to magnetic materials without purification, but its process flow is complex, covers a large area, the infrastructure cost is high, the need for special maintenance force, more operators, slow gas production (18 24h), it is suitable for large-scale industrial nitrogen production, nitrogen cost is about 0 7 yuan m3.

2. Pressure swing adsorption nitrogen production.

Pressure swing adsorption gas separation technology is an important branch of non-cryogenic gas separation technology, which is the result of long-term efforts to find a simpler air separation method than cryogenic method. In the seventies, the West German mining company Essen successfully developed a carbon molecular sieve, which paved the way for the industrialization of PSA air separation nitrogen production. In the past 30 years, the technology has developed rapidly and matured, and has become a strong competitor in the field of small and medium-sized nitrogen production.

Pressure swing adsorption nitrogen production is based on air as raw material, using carbon molecular sieve as adsorbent, using carbon molecular sieve to select adsorption characteristics of oxygen and nitrogen in the air, using the principle of pressure swing adsorption (pressure adsorption, decompression desorption and molecular sieve regeneration) and separating oxygen and nitrogen at room temperature to produce nitrogen.

3. Membrane separation for nitrogen production.

Membrane separation nitrogen production is to use air as raw material, under a certain pressure, using the different permeation rates of oxygen and nitrogen in the hollow fiber membrane to separate oxygen and nitrogen to produce nitrogen. Compared with the above two nitrogen production methods, it has the characteristics of simpler equipment structure, smaller size, no switching valve, easier operation and maintenance, faster gas production (less than 3min), and more convenient capacity increase.

However, the hollow fiber membrane has stricter requirements for the cleanliness of compressed air, the membrane is easy to age and fail, difficult to repair, and needs to be replaced with a new membrane.

When the purity of nitrogen is required to be higher than 98%, it is about 30% higher than that of the pressure swing adsorption nitrogen production device of the same specification, so when the high-purity nitrogen is produced by the combination of membrane separation nitrogen production and nitrogen purification device, the purity of general nitrogen is generally 98%, which will increase the production cost and operating cost of the purification device.

Methods of industrial ammonia production:

1. Brown's Three Towers.

Three waste pot ammonia synthesis circles.

The Brown Three Towers and Three Waste Pots Ammonia Synthesis Circle consists of 3 synthesis towers and 3 waste pots. There is a catalyst basket in the tower, and the gas flows from the bottom to the top through the gap between the shell and the basket body, and then from the top to the bottom axial.

Flow through the catalyst bed.

The loading capacity of the catalyst in the third tower is more than that in the second tower, and the final export ammonia content can be increased to more than 21%, which reduces the amount of circulating gas and saves the circulating compression work. The control system of the synthesis tower is very simple, and each tower is equipped with a bypass to adjust the temperature of the gas entering the tower with a valve.

2. Wood's two towers, three beds, two waste pots, ammonia synthesis circles.

Wood's two-tower, three-bed, two-waste pot ammonia synthesis circle adopts two smaller synthesis towers, three catalyst beds, and a waste pot is connected to each of the two towers. This structure makes the reaction temperature distribution very close to the optimal reaction temperature, the circulation volume and pressure drop of the gas are small, the investment and energy consumption are saved, and the by-product high-pressure steam is more.

3. Topsoe's two towers, three beds, two waste pots, ammonia synthesis rings.

The Topsoe S-250 system consists of an S-200 synthesis tower and an S-50 synthesis tower without lower heat exchange. Also includes: waste heat from waste pots and boiler feedwater heat exchangers; Synthesis tower inlet and outlet air heat exchanger, water cooler, ammonia cooler and cold exchanger, ammonia separator and fresh gas ammonia cooler, etc.

The synthesis tower is a radial flow catalyst bed, using a small catalyst with a pressure drop of . The syngas from the S-200 tower is heated by the waste heat boiler and the appropriate temperature into the S-50 tower is ensured to improve the single-pass synthesis rate.

4. Ammonia production from industrial natural gas.

Natural gas is first desulphished, then converted twice, and then passed through carbon monoxide separately.

Shift, carbon dioxide.

removal and other processes, the obtained nitrogen-hydrogen mixture, which still contains carbon monoxide and carbon dioxide about volume).

Methane. After the chemical action is removed, pure gas with a molar ratio of hydrogen to nitrogen of 3 is prepared, which is compressed by the compressor and enters the ammonia synthesis circuit to obtain product ammonia. Take naphtha.

The process of producing ammonia as a feedstock is similar to this process.

5. Ammonia production from industrial heavy oil.

Heavy oil includes residue oil obtained from various deep processing, and synthetic ammonia raw gas can be prepared by partial oxidation method, and the production process is simpler than that of natural gas vapor reforming, but an air separation device is required. The oxygen produced by the air separation unit is used for heavy oil and gasification, and nitrogen is used as a raw material for ammonia synthesis, liquid nitrogen.

It is also used as a detergent to remove carbon monoxide, methane and argon.

Encyclopedia - Ammonia.

Encyclopedia - Ammonia Preparation Method.

Nitrogen is prepared by heating a mixture of a saturated solution of ammonium chloride and sodium nitrite crystals (or a saturated solution). A double-hole rubber stopper is placed on a round-bottom flask, with a separating funnel and a short-bent catheter. Put sodium nitrite crystals (or saturated solution) in the flask, and the saturated ammonium chloride solution is dropped into the separating funnel, and the flask is heated to about 85, and nitrogen is generated.

When the air is discharged, nitrogen can be collected by draining gas collection or directly with a rubber ball bladder. Because this reaction is exothermic, the heating should be stopped when the reaction starts. The chemical equation is:

nano2+nh4cl==nh4no2+nacl

nh4no2 n2↑+2h2o

Liquid air is then evaporated according to the different boiling points of oxygen and nitrogen. The nitrogen obtained in this way can basically be used in general production, and if higher purity is required, chemical reactions are needed to help.

Solids such as phosphorus are burned in a closed container, and the purer nitrogen is left.

Take it in the air, because more than 6 percent of the air is nitrogen, which undergoes a chemical reaction.

The common production methods of nitrogen are: air liquide fractionation, low-temperature separation, membrane separation, pressure swing adsorption, pressure swing absorption, etc.

Liquid air fractionated nitrogen: It is mainly produced by separating or breaking down nitrogen-containing compounds from the atmosphere. Air Liquide produces more than 33 million tonnes of nitrogen per year, which is then produced by fractionation and other gases in the atmosphere.

Low-temperature separation: The low-temperature separation process, also known as the low-temperature distillation process, utilizes the different boiling points of nitrogen and oxygen in the air to separate oxygen and nitrogen. Since the boiling point of nitrogen (-196) is lower than the boiling point of oxygen, liquid nitrogen becomes a gas more easily than liquid oxygen during the evaporation of liquid air, while oxygen becomes a liquid more easily than nitrogen during air liquefaction.

Since the boiling points of nitrogen and oxygen are not very different, liquid and gaseous air must undergo repeated processes of evaporation, condensation, and re-evaporation (this process is called cryogenic distillation).

Membrane separation process

Membrane separation technology is based on the selective permeation and diffusion characteristics of gas components in the membrane to achieve the purpose of gas separation and purification. The velocity of the different components of the gas flowing through the membrane is different, and the rate at which each component flows through the membrane is related to the type of gas, the characteristics of the membrane, and the partial pressure difference between the two sides of the membrane. The composition of the gas entering the membrane cannot be 100% pure.

Gas separation membranes can generally be divided into porous and non-porous materials, and Changdongtou is composed of inorganic substances (porous glass, ceramics, metals, conductive solids and palladium alloys, etc.) or organic polymers (microporous polyethylene, porous acetate, homogeneous acetate, polysiloxane rubber and polycarbonate). The purified compressed air enters through a buffer tank and a combination filter from one end of the membrane pack.

Under pressure, the gas molecules first come into contact with the high-pressure side of the membrane. The mixed gas dissolves in the membrane at different solubility levels on the surface of the high-pressure side of the membrane, and then the molecules of the mixed gas diffuse to the low-pressure side of the membrane at different speeds and create a pressure difference on both sides of the membrane. After the selection of the two solutions and the diffusion process, the gas mixture is finally separated into different components.

For example, air and oxygen are permeable faster than nitrogen. After membrane separation, the gas that remains on the high-pressure side is enriched with nitrogen, while the gas that passes through is enriched with oxygen.

Question 1: The method of preparing nitrogen in the industrial production of Tara separates the liquid air.

The air is pressurized and cooled, and then gradually heated, and N2 O2 is successively vaporized into gas to achieve the purpose of separation.

The boiling of N2 is -196 degrees, and O2 is -183 degrees, so when liquid air is vaporized, N2 is obtained first

Nitrogen gas can be generated by the reaction of azo clear yoyo slippery compounds and hydrogen peroxide.

Question 2: How to make nitrogen Direct air fractionation is an industrial extraction method. If you want to extract nitrogen in the laboratory, you need to mix the ammonium chloride saturated solution with sodium nitrite solid and heat it.

The nitrogen extracted in this way is mixed with water vapor, which can be removed in another container with desiccants such as concentrated sulfuric acid, soda lime, calcium oxide, anhydrous calcium chloride, anhydrous magnesium sulfate, etc.

For specific chemical reaction equations, please bring your own trimming:

Ammonium chloride + sodium nitrite = = sodium chloride + water + nitrogen.

Due to the influence of impurities in the reaction, the solution may turn yellow or even black; Nitrogen is not produced slowly and can be heated using a boiling water bath.

Question three: How is nitrogen made and separated from the air?

There are three main methods for making nitrogen:

1. Nitrogen production by air separation of molecular sieve: It is a method of separating nitrogen and oxygen by using air as raw material, carbon molecular sieve as adsorbent, using the principle of pressure swing adsorption, and using carbon molecular sieve to selectively adsorb oxygen and nitrogen;

2. Cryogenic air separation nitrogen production: It is a traditional nitrogen production method with a history of nearly 90 years. It uses air as raw material to lease luggage, compresses, purifies, and then uses heat exchange to liquefy air liquide.

Air Liquide is mainly a mixture of liquid oxygen and liquid nitrogen, using the different boiling points of liquid oxygen and liquid nitrogen, through the distillation of Air Liquide, so that they are separated to obtain nitrogen;

3. Membrane air separation nitrogen production: It is another new type of nitrogen production technology that developed rapidly abroad in the eighties, and it has been popularized and applied in China in the past three or four years. The basic principle of membrane air separation nitrogen production is to use air as raw material, and under certain pressure conditions, use gases with different properties such as oxygen and nitrogen to separate oxygen and nitrogen in the membrane.