Liquid ammonia, also known as anhydrous ammonia, is a colorless liquid. As an important chemical raw material, ammonia is widely used. In order to facilitate transportation and storage, liquid ammonia is usually obtained by pressurizing or cooling gaseous ammonia. Liquid ammonia is widely used in industry, which is corrosive and volatile, so the incidence of chemical accidents is quite high. ?
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Introduction?
Physical and chemical properties?
Product use?
The source of liquid ammonia?
Synthetic ammonia?
1.3. 1? High pressure method?
1.3.2? Medium pressure method?
1.3.3? Low pressure method?
Other sources of packaging, storage and transportation?
Poisoning disposal?
Toxicity and poisoning mechanism?
Exposure route and poisoning symptoms?
First aid measures, waste gas recovery?
2065438+2002 China liquid ammonia market trend analysis and introduction?
Physical and chemical properties?
Product use?
The source of liquid ammonia?
Synthetic ammonia?
1.3. 1? High pressure method?
1.3.2? Medium pressure method?
1.3.3? Low pressure method?
Other sources of packaging, storage and transportation?
Poisoning disposal?
Toxicity and poisoning mechanism?
Exposure route and poisoning symptoms?
First aid measures, waste gas recovery?
20 12 China liquid ammonia market trend analysis editor introduces this paragraph? Liquid? Ammonia (anhydrous? Ammonia)?
Structure and molecular formula NH3?
How to make it? Synthetic ammonia is compressed to produce liquid ammonia products. ?
Product performance? Liquid ammonia is a colorless liquid with a strong pungent smell, which can be easily gasified into gaseous ammonia. The density is 0.617g/cm3; The boiling point is -33.5℃, which is lower than -77.7℃, and it can become colorless crystals with odor. ?
Edit the physical and chemical properties of this paragraph: NH3? Relative density of gaseous ammonia (air = 1): 0.59? Molecular weight: 17.04 Relative density of liquid ammonia (water = 1): 0.602824 (25℃)?
CASNo.: 7664-4 1-7 Autoignition point: 651.1℃?
Dangerous goods code:? 23003? Molecular weight:? 17.03?
Melting point (℃):-77.7? Explosion limit: 16% ~ 25%?
Boiling point (℃):-33.4? PH value of 1% aqueous solution: 1 1.7?
Specific heat kj (kg k)? Ammonia (liquid) 4.609? Ammonia (gas) 2. 179?
Steam pressure: 882 kPa (20℃)?
Self-coupling ionization: 2NH3? NH4+？ +NH2-？
So in liquid ammonia, NH4Cl is an acid and NaNH2 is an alkali?
Edit this product use "20 13-20 17 China Liquid Ammonia Industry Investigation and Investment Prospect Evaluation Report". Liquid ammonia is mainly used to produce fertilizers such as nitric acid and urea, and can also be used as raw materials for medicine and pesticides. ?
Liquid ammonia
In the national defense industry, it is used to make propellants for rockets and missiles. It can be used as ammoniation raw material for organic chemical products and also as refrigerant. Liquid ammonia can also be used for mercerizing finishing of textiles. Solitary electron pairs in NH3 molecules tend to form coordination bonds with other molecules or ions, thus forming various forms of ammonia compounds. For example, [Ag(NH3)2]+, [Cu(NH3)4]2+ and BF3 NH3 are all complexes with NH3 as the coordination. ? Liquid ammonia is a good solvent. Liquid ammonia is very similar to water in many physical properties because of the polarity of molecules and the existence of hydrogen bonds. Some active metals can replace hydrogen from water to generate hydroxide, but it is not so easy to replace hydrogen in liquid ammonia. But liquid ammonia can dissolve metals and form blue solutions. This metal liquid ammonia solution can conduct electricity and slowly decompose to release hydrogen, which is very reductive. For example, the liquid ammonia solution of sodium:? The reason why metal liquid ammonia solution is blue, conductive and strongly reducing is that "ammonia electrons" are produced in the solution. For example, when sodium metal is dissolved in liquid ammonia, it loses valence electrons and produces positive ions.
Liquid ammonia is heated to 800 ~ 850℃, and ammonia is decomposed under the action of nickel-based catalyst to obtain hydrogen-nitrogen mixed gas containing 75%H2 and 25%N2. The gas produced by this method is a good protective gas, which can be widely used in industries and scientific research that need protective atmosphere, such as semiconductor industry and metallurgical industry. ?
Synthetic ammonia is the source of liquid ammonia and the last process of synthetic ammonia production. Its task is to synthesize ammonia from refined hydrogen-nitrogen mixture quickly and economically under the action of catalyst. For the synthesis system, liquid ammonia is its product. ?
Various industrial synthetic ammonia processes are generally classified according to pressure. ?
1.3. 1? The operating pressure of high pressure method is 70 ~ 100 MPa, and the temperature is 550 ~ 650℃. The main advantages of this method are high ammonia synthesis efficiency and easy separation of ammonia in the mixed gas. So the process and equipment are relatively compact. However, the catalyst has high synthesis efficiency, large heat release, high temperature, easy overheating deactivation and short service life. Because it is operated at high temperature and high pressure, it requires high equipment manufacturing and materials, and the investment cost is high. At present, this method is rarely used in industry. ?
1.3.2? The working pressure of medium pressure method is 20 ~ 60 MPa and the temperature is 450 ~ 550℃, and its advantages and disadvantages are between high pressure method and low pressure method. At present, this method has mature technology and good economy. Because the determination of combined pressure is nothing more than considering the equipment investment and compression power consumption. In terms of power consumption, the power consumption of the synthesis system accounts for the largest proportion of the total power consumption of the whole plant. But power consumption never depends on pressure, but also depends on other process indicators and process layout. Generally speaking, in the range of 15 ~ 30pa, there is little difference in power consumption, so this method is widely used internationally. ?
1.3.3? The operating pressure of low pressure method is about 10MPa, and the temperature is 400 ~ 450℃. The advantages of this method are relatively low operating pressure and temperature, low requirements for equipment, easy management and high catalyst activity. However, the catalyst used in this method is very sensitive to poisons, easy to be poisoned and short in service life, so the refined purity of raw gas is strictly required. Due to the low operating pressure, the ammonia synthesis efficiency is low, the separation is difficult and the process is complex. This method is no longer used in actual industrial production. The process flow of synthetic ammonia can be roughly divided into: preparation of feed gas; Purification of feed gas; Gas compression and ammonia synthesis. ?
In the process of continuous production of diphenylamine with aniline from other sources under the action of catalyst, by-product ammonia will be produced, which will be compressed into high-pressure gas and then cooled into liquid ammonia. In this process, sewage is discharged and impurities are brought in. Therefore, compared with high-purity synthetic ammonia, the purity of liquid ammonia obtained by this method is relatively low, so its use is limited. ?
Edit this paragraph, the packaging, storage and transportation of liquid ammonia are classified as 2.3? Toxic gas?
Fill with steel cylinder or tank car. Filling steel cylinders or tank trucks should meet the requirements of the State Labor Bureau?
Liquid ammonia storage tank
Regulations on Safety Supervision of Gas Cylinders, Regulations on Safety Technology Supervision of Fixed Pressure Vessels and other relevant regulations. The allowable weight filling coefficient is 0.52kg/l. Gas cylinders and tank trucks carrying liquid ammonia must comply with the rules for the transport of dangerous goods formulated by the Ministry of Communications of People's Republic of China (PRC) and People's Republic of China (PRC). High temperature should be avoided during transportation, and fireworks are strictly prohibited. Gas cylinders must have safety helmets, and the bottle body should be wrapped with rubber bands or straw ropes to prevent violent impact and vibration. Liquid ammonia cylinders should be stored in a shed warehouse or platform. When stacked in the open air, tents should be built to prevent direct sunlight. It is mainly transported by rail and road. ?
Edit the toxicity and poisoning mechanism of poisoning disposal in this paragraph. Tdlo of liquid ammonia passing through human mouth: 0.15? ML/kg?
Liquid ammonia inhaled by human body LCLo:5000? ppm/5m？
After ammonia enters the human body, it will hinder the circulation of tricarboxylic acid and reduce the role of cytochrome oxidase. The increase of brain ammonia can produce neurotoxic effect. High concentration of ammonia can cause tissue dissolution and necrosis. ?
Exposure route and poisoning symptoms?
Liquid ammonia
1. Inhale?
Inhalation is the main route of contact. The irritation of ammonia is a reliable alarm signal of harmful concentration. However, due to olfactory fatigue, it is difficult to detect low concentration of ammonia after long-term contact. ?
(1) Mild inhalation ammonia poisoning is characterized by rhinitis, pharyngitis, tracheitis and bronchitis. The patient has burning throat, cough, expectoration or hemoptysis, chest tightness and retrosternal pain. ?
(2) Acute ammonia inhalation poisoning is mostly caused by accidents such as pipeline rupture and valve burst. Acute ammonia poisoning is mainly manifested as irritation and burns of respiratory mucosa. Its symptoms vary with ammonia concentration, inhalation time and personal sensitivity. ?
(3) Severe inhalation poisoning can cause laryngeal edema, glottic stenosis, respiratory mucosa shedding, and can cause tracheal obstruction and asphyxia. Inhalation of high concentration can directly affect pulmonary capillary permeability and cause pulmonary edema. ?
2. Skin and eye contact?
Low concentrations of ammonia can quickly irritate eyes and moist skin. Wet skin or eyes exposed to high concentrations of ammonia can cause serious chemical burns. ?
Skin contact can cause severe pain and burns, and coffee-like color can appear. The corroded part is gelatinous and soft, which can cause deep tissue damage. ?
High-concentration steam has strong irritation to eyes, which can cause pain and burns, lead to obvious inflammation, and may cause edema, epithelial tissue destruction, corneal opacity and iris inflammation. Mild cases will generally be relieved, and severe cases can last for a long time, and there will be complications such as persistent edema, scar, permanent turbidity, exophthalmos, cataract, eyelid and eyeball adhesion, blindness and so on. Repeated or continuous exposure to ammonia can lead to conjunctivitis. ?
Emergency measures 1. Clean up pollution?
If the patient is only exposed to ammonia and has no skin and eye irritation symptoms, there is no need to clean up the pollution. If you come into contact with liquid ammonia and your clothes are contaminated, you should take off your clothes and put them in a double plastic bag. ?
Liquid ammonia accident
In case of accidental eye contact or irritation, please rinse with plenty of water or normal saline for more than 20 minutes. If blepharospasm occurs during flushing, slowly drop 1 ~ 2 drops of 0.4% oxybupivacaine and continue to flush fully. If the patient wears contact lenses, which are easy to take off and will not damage the eyes, then the contact lenses should be taken off. ?
Contact with skin and hair should be washed with plenty of water 15 minutes or more. Pay attention to protect your eyes when washing your skin and hair. ?
2. Patient resuscitation?
The patient should be removed from the contaminated area immediately and resuscitated in three steps (airway, breathing and circulation):?
Airway: make sure the airway is not blocked by tongue or foreign body. ?
Breathing: check whether the patient is breathing. If not, provide ventilation with a pocket mask.
Circulation: check the pulse, and if there is no pulse, perform cardiopulmonary resuscitation. ?
3. Initial treatment?
There is no specific antidote for ammonia poisoning, so supportive treatment should be taken. ?
If the exposure concentration is ≥500ppm, and there are symptoms of eye irritation and pulmonary edema, it is suggested to take the following measures: spray dexamethasone five times (using metered-dose inhaler) first, and then spray it twice every five minutes until it reaches the emergency room of the hospital. ?
If the exposure concentration is ≥ 1500ppm, an intravenous route should be established, and intravenous injection of 1.0g methylprednisolone or equivalent steroids should be conducted. (Note: The effect of corticosteroids has not been confirmed in clinical controlled studies. )?
For ammonia inhalers, humidified air or oxygen should be given. If there are symptoms of hypoxia, humidified oxygen should be given. ? If respiratory distress occurs, tracheal intubation should be considered. When the patient's condition prevents tracheal intubation, cricothyroid chondrotomy should be performed if possible. For patients with bronchospasm, bronchodilators such as terbutaline can be sprayed. ? If the skin comes into contact with ammonia, it will cause chemical burns, which can be treated as thermal burns: properly replenish water, give painkillers, keep body temperature, and cover the injured surface with disinfection pads or clean sheets. If the skin comes into contact with high-pressure liquid ammonia, pay attention to frostbite. ?
In this section, waste gas is discharged in the process of liquid ammonia finishing. The waste gas consists of steam, air and ammonia, among which ammonia is a harmful gas, which affects health and pollutes the environment. Therefore, to reduce emissions and strengthen recycling can reduce costs on the one hand and protect the environment on the other. ?
Liquid ammonia alarm
There is an absorption method to recover ammonia. The gas discharged from the liquid ammonia finishing machine is transported to the washing tower (absorption tower) of the recovery device through pipelines, and ammonia mixed with air is absorbed into ammonia water in this tower. At this time, the air is washed out of the tower, and then ammonia is separated from water by a distillation tower, and the ammonia is distilled and absorbed into concentrated ammonia water, which is rectified into concentrated ammonia water, pressurized by a compressor, condensed and cooled into liquid ammonia, and finally input into a storage tank. ?
In the ammonia recovery device, there is an exhaust port at the top of the washing tower, so the ammonia content in the waste gas should be controlled to be lower than the environmental protection requirements. The ammonia recovery system jointly developed by Chengjiang Textile Machinery Factory and Nanjing University of Chemical Technology is a method combining absorption and compression. China Textile Machinery and Equipment Association organized an expert field trip on June 5438+ 10, 2000, and agreed that the ammonia recycling system was successful. The whole recycling system creatively adopted the "three lows and one pressure" technology of low-pressure absorption, low-pressure rectification, low-temperature dehydration and compression condensation, which not only simplified the equipment, but also saved energy. This method is operated at low temperature and low pressure, with high safety factor, which is conducive to reducing maintenance power. It mainly includes washing tower (absorption tower), rectifying tower, compressor, condenser and liquid ammonia storage tank. ?
Liquid ammonia monitoring and alarm?
When liquid ammonia leaks during use, an alarm must be given. The liquid ammonia leakage alarm device and automatic filling and cutting alarm device produced by Baoji Keightley Electronics Company meet the requirements of national technical supervision and security inspection departments. ?
The pressure of liquid ammonia?
Because the critical temperature of ammonia is 132.4℃, it can be liquefied below this temperature as long as appropriate pressure is given. ?
At room temperature, it takes about 7 ~ 8 atmospheres to liquefy ammonia into liquid ammonia for storage. ?
However, the actual use temperature may not be normal temperature, and the saturated vapor pressure is required not to be lower than 50℃ in the design of our country. The design pressure of liquid ammonia container should be 2. 16MPa?
Edit this paragraph 20 12 Analysis on the trend of liquid ammonia market in China. In recent years, the problem of overcapacity in the coal chemical industry has become more prominent. From 20 1 1 to 20 12, China's total synthetic ammonia capacity reached 6.26 million tons, and urea capacity reached12.78 million tons. From June 2065438 to June 2002, China's domestic synthetic ammonia output was about 4.578 million tons. From October to June, 2065438+0/KLOC-0, the domestic output of synthetic ammonia was about 4.395 million tons. It increased by 4% year-on-year. From June to June, the total output of synthetic ammonia in China was about 27 1 1.4 million tons. /kloc-from October to June, the total output of synthetic ammonia in China was about 25.322 million tons, up 6.6% year-on-year. The overproduction of synthetic ammonia in China has led manufacturers to cut prices and the transactions in various regions are basically smooth. ?
In the first half of 20 12, the domestic liquid ammonia market was unstable and the overall market fluctuated. In the first half of the year, the highest price of liquid ammonia was 3,250 yuan/ton in the mainstream price of liquid ammonia in northern Jiangsu and 3,500 yuan/ton in southern Jiangsu. The mainstream of liquid ammonia in Jiangnan, Anhui Province accepted 3,350 yuan/ton, and that in Jiangbei, Anhui Province accepted 3,250 yuan/ton. The ex-factory price of liquid ammonia in Hebei is about 2950-3000 yuan/ton. Shandong liquid ammonia mainstream 3 100-3 150 yuan/ton spot. Supported by the good demand of urea and compound fertilizer, the ex-factory price of liquid ammonia continues to be high. The lowest price of synthetic ammonia in the first half of the year is the mainstream ex-factory price of 2650-2700 yuan/ton in Hebei market. The ex-factory price in Shandong is 2700-2800 yuan/ton, and that in northern Jiangsu is 2900 yuan/ton. ?
Judging from the current market, the fluctuation of domestic liquid ammonia will not be too great, that is, when China is put into production in 20 12, more liquid ammonia plants will expand their production, but the basic supply and demand can be balanced. New liquid ammonia plant, urea and other downstream products are also under construction. From August to September, China's agriculture was in the harvest period, agricultural demand weakened, and the market was dominated by weakness. It is expected that the liquid ammonia market will fluctuate within a narrow range in the second half of the year, and the price of liquid ammonia in the north will remain at 2900-3000 yuan/ton. [ 1]?