1. Nitrogen bottle

The cylinder volume is 40L, the rated pressure is 15MPa, and the full gas storage is 6m3. According to different needs of users, the purity of bottled nitrogen is 99.5%, 99.999% and 99.999%. Due to the different supply and demand in different places, the price of bottled high-purity nitrogen varies greatly, ranging from 18 to 90 yuan/bottle, that is, the nitrogen price is 3 to 15 yuan/m3.

2. Liquid nitrogen

Liquid nitrogen is the product of cryogenic air separation nitrogen production. Under standard conditions, 1m3 of liquid nitrogen can be gasified into 643m3 of nitrogen, but the actual utilization rate during use is generally around 95%, that is, the nitrogen that 1m3 of liquid nitrogen can actually use. About 610m3 or so. At present, the average price of liquid nitrogen in the market is about 1,000 yuan/m3, and the unit price of nitrogen is 1.67 yuan/m3. When using liquid nitrogen, the user must be equipped with a liquid nitrogen storage tank, a vaporizer corresponding to the flow rate, and a pressure regulating valve corresponding to the pressure, which is a necessary initial investment.

3. Nitrogen production on site

On-site nitrogen production refers to nitrogen production with nitrogen production equipment purchased by nitrogen users. At present, there are three types of industrial-scale nitrogen production at home and abroad: cryogenic air separation nitrogen production, pressure swing adsorption nitrogen production and membrane separation nitrogen production.

3.1 Nitrogen production by cryogenic air separation

It is a traditional air separation technology with a history of more than 90 years. It is characterized by large gas production and high nitrogen purity. However, it has a complex process, a large area and high infrastructure costs, requiring special Maintenance force, many operators, slow gas production (18 ~ 24h), it is suitable for large-scale industrial nitrogen production, and the nitrogen cost is about 0.7 yuan/m3.

3.2 PSA nitrogen production

Pressure Swing Adsorption (PSA) gas separation technology is an important branch of non-cryogenic gas separation technology. It is the result of people's long-term efforts to find a simpler air separation method than the cryogenic method. A strong competitor to cryogenic air separation. It uses air as raw material, uses carbon molecular sieve as adsorbent, utilizes the characteristics of carbon molecular sieve to selectively adsorb oxygen and nitrogen in the air, and uses the principle of pressure swing adsorption (pressure adsorption, decompression desorption and molecular sieve regeneration) at room temperature. Separation of oxygen and nitrogen to produce nitrogen. Compared with cryogenic air separation nitrogen production, pressure swing adsorption nitrogen production has remarkable characteristics: adsorption and separation is carried out at room temperature, the process is simple, the equipment is compact, the area is small, the start and stop are convenient, the start-up is rapid, and the gas production is fast ( Generally about 20~30min), low energy consumption, low operating cost, high degree of automation, convenient operation and maintenance, convenient skid installation, no need for special foundation, product nitrogen purity can be adjusted within a certain range, nitrogen production ≤ 2000Nm3/h. The cost of nitrogen is about 0.4 yuan/m3.

3.3 Nitrogen production by membrane separation air separation

Membrane separation air separation nitrogen production is also a new branch of non-low temperature nitrogen production technology. It is a new nitrogen production method developed rapidly abroad in the 1980s. It uses air as raw material, and under certain pressure, utilizes 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 volume, no switching valve, easier operation and maintenance, faster gas production (within 3 minutes), and more convenient capacity expansion. The fiber membrane has stricter requirements on the cleanliness of the compressed air. The membrane is easy to age and fail, and it is difficult to repair. It needs to be replaced with a new membrane. The membrane separation nitrogen production is more suitable for small and medium-sized users whose nitrogen purity requirements are less than or equal to 98%. At this time, it has the best function. Price ratio: When the nitrogen purity is required to be higher than 98%, the price is about 30% higher than that of the pressure swing adsorption nitrogen generator of the same specification, so there is no competitive advantage.