Liquid ammonia is a colorless liquid with a strong pungent odor. Ammonia, as an important chemical raw material, is widely used. For convenient transportation and storage, gaseous ammonia is usually pressurized or cooled to obtain liquid ammonia. Ammonia is easily soluble in water and forms an alkaline solution of ammonium hydroxide when dissolved in water. The solubility of ammonia in water at 20 ℃ is 34%. Liquid ammonia is widely used in industry, and it is corrosive and easily volatile, so its chemical accident rate is quite high.

1、 Product Usage

Liquid ammonia is mainly used in the production of nitric acid, urea, and other chemical fertilizers, and can also be used as a raw material for pharmaceuticals and pesticides. In the defense industry, it is used to manufacture propellants for rockets and missiles. It can be used as an ammonification raw material for organic chemical products and also as a refrigerant.

2、 Packaging, storage and transportation

Fill with steel cylinders or tank trucks. Steel cylinders or tank trucks used for filling shall comply with relevant regulations such as the "Gas Cylinder Safety Supervision Regulations" and the "Pressure Vessel Safety Supervision Regulations" issued by the National Labor Bureau. The allowable weight filling coefficient is 0.52kg/L. Steel cylinders and tank trucks used for transporting liquid ammonia must comply with the "Dangerous Goods Transport Regulations" formulated by the Ministry of Transport of the People's Republic of China. During transportation, they should avoid heating and smoking is strictly prohibited. Steel cylinders must be equipped with safety helmets and wrapped with rubber bands or grass ropes to prevent severe impact and vibration. Liquid ammonia cylinders should be stored in warehouses or on covered platforms. When storing outdoors, tents should be used to cover and prevent direct sunlight. Mainly relying on railway and road transportation.

3、 Symptoms of poisoning

Inhalation is the main route of contact. The irritability of ammonia is a reliable warning signal for harmful concentration. However, due to olfactory fatigue, it is difficult to detect low concentrations of ammonia after long-term exposure.

(1) Mild inhalation ammonia poisoning manifests as rhinitis, pharyngitis, tracheitis, and bronchitis. The patient has sore throat, cough, sputum or hemoptysis, chest tightness, and pain behind the sternum.

(2) The occurrence of acute inhalation ammonia poisoning is often caused by accidents such as pipeline rupture, valve rupture, etc. Acute ammonia poisoning is mainly characterized by irritation of the respiratory mucosa and burns. The severity of its symptoms varies depending on the concentration of ammonia, inhalation time, and personal sensitivity.

(3) Severe inhalation poisoning can lead to laryngeal edema, glottal stenosis, and respiratory mucosal detachment, which can cause tracheal obstruction and suffocation. Inhaling high concentrations can directly affect pulmonary capillary permeability and cause pulmonary edema.

Low concentrations of ammonia can quickly cause irritation to the eyes and damp skin. Wet skin or eyes exposed to high concentrations of ammonia can cause severe chemical burns.

Skin contact can cause severe pain and burns, and can lead to coffee like discoloration. The corroded area appears gelatinous and soft, and can cause deep tissue damage.

High concentration vapor has strong irritant effects on the eyes, causing pain and burns, leading to significant inflammation and possible edema, epithelial tissue damage, corneal opacity, and iris inflammation. Mild cases generally experience relief, while severe cases may persist for a long time and develop complications such as persistent edema, scarring, permanent opacity, eye protrusion, cataracts, eyelid and eyeball adhesions, and blindness. Repeated or continuous exposure to ammonia can lead to conjunctivitis.

4、 Emergency measures

If the patient is only exposed to ammonia gas and has no skin or eye irritation symptoms, there is no need to remove the pollution. If the contact is with liquid ammonia and the clothes have been contaminated, the clothes should be taken off and placed in a double-layer plastic bag.

If there is eye contact or irritation, rinse with plenty of water or saline solution for more than 20 minutes. If eyelid spasms occur during flushing, 1-2 drops of 0.4% ibuprofen should be slowly added and thoroughly rinsed. If the patient wears contact lenses that are easy to remove and will not damage the eyes, the contact lenses should be removed.

Rinse the skin and hair in contact with plenty of water for at least 15 minutes. Be careful to protect your eyes when washing your skin and hair.

The patient should be immediately transferred out of the contaminated area and undergo a three-step resuscitation procedure (airway, respiration, circulation):

Airway: Ensure that the airway is not blocked by the tongue or foreign objects.

Breathing: Check if the patient is breathing, and if there is no breathing, provide ventilation with a pocket mask, etc,

Circulation: Check the pulse, and if there is no pulse, perform cardiopulmonary resuscitation.

There is no specific antidote for ammonia poisoning, and supportive treatment should be used.

If the exposure concentration is ≥ 500ppm and symptoms of eye irritation and pulmonary edema occur, the following measures are recommended: first spray dexamethasone 5 times (using a quantitative inhaler), then spray twice every 5 minutes until reaching the emergency room of the hospital.

If the exposure concentration is ≥ 1500ppm, intravenous access should be established and 1.0g methylprednisolone or an equivalent amount of steroids should be injected intravenously. (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 there is respiratory distress, tracheal intubation should be considered. When the patient's condition does not allow for tracheal intubation, if conditions permit, cricoid cartilage incision should be performed. For patients with bronchospasm, bronchodilator spray can be given, such as terbutamol. If the skin comes into contact with ammonia, it can cause chemical burns. It can be treated as a thermal burn: appropriate fluid replacement, administration of painkillers, maintenance of body temperature, and covering the injured surface with disinfectant pads or clean bed sheets. If the skin comes into contact with high-pressure liquid ammonia, pay attention to frostbite.

5、 Waste gas recovery

The process of liquid ammonia processing involves the discharge of waste gas, which consists of water vapor, air, and ammonia. Among them, ammonia is a harmful gas that affects health and pollutes the environment. Therefore, it is necessary to reduce emissions and strengthen recycling, which can reduce costs and protect the environment.

There is an absorption method for ammonia recovery. The gas discharged from the liquid ammonia sorting machine is transported through pipelines to the washing tower (absorption tower) of the recovery device. The ammonia mixed with air is absorbed into ammonia water in the tower, and the air is cleaned and discharged outside the tower. Then, the ammonia and water are separated through a distillation tower, and the ammonia is distilled and absorbed to produce concentrated ammonia water. The concentrated ammonia water is distilled to produce concentrated ammonia water, which is then compressed and condensed by a compressor to cool 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, and the ammonia content in the exhaust gas should be controlled to be lower than the environmental requirements. The ammonia recovery system created in collaboration between Chengjiang Textile Machinery Factory and Nanjing University of Chemical Technology is a combination of absorption and compression methods. In January 2000, experts organized by the China Textile Machinery Equipment Association conducted an on-site inspection and unanimously agreed that the ammonia recovery cycle system was successful. The entire recovery system creatively utilized the "three lows and one pressure" technology of low-pressure absorption, low-pressure distillation, low-temperature water removal, and compression condensation, which not only simplified the equipment but also saved energy. This method operates at low temperature and low pressure, with a high safety factor and reduced maintenance costs. There are mainly washing towers (absorption towers), distillation towers, compressors, condensers, and liquid ammonia storage tanks.