What are the dangers of ethylene glycol explosion?

Recently, everyone must have seen the news of a fire in the ethylene glycol unit of Sinopec Shanghai Petrochemical Chemical Department. Witnesses said that the fireball shot straight into the sky and there were explosions in many places. The on-site video showed that after the fire broke out, the flames spread and the entire plant was covered with black smoke. The fire has so far caused one death and one injury, and the cause of the accident is still under investigation.

Today we are going to talk to you about what ethylene glycol is and what are the dangers of ethylene glycol explosion?

01. What is ethylene glycol?

What is Ethylene Glycol?

Ethylene glycol is also known as glycol, 1,2-ethylene glycol, or EG for short. Its chemical formula is (CH₂OH)₂, and it is the simplest diol. Ethylene glycol is a colorless, odorless, sweet-tasting liquid with low toxicity to animals. Ethylene glycol is miscible with water and acetone, but has a lower solubility in ethers. It is used as a solvent, antifreeze, and raw material for synthetic polyester.

02. What are the dangers of ethylene glycol explosion?

The danger of ethylene glycol explosion should be explained from four aspects, as follows:

1. Risks of ethylene glycol itself

Ethylene glycol itself is a low-toxic product. The oral median lethal dose in mice is LD50=1.31~13.8mL/kg, so it is not very toxic.

Generally, chronic poisoning is the main cause, while acute poisoning is mainly caused by accidental ingestion, which can cause central nervous system poisoning to further spread to the heart, lungs and other parts.

2. Risk of product from ethylene glycol explosion

Normal and complete combustion of ethylene glycol will produce carbon dioxide and water, which is non-toxic. However, during rapid deflagration, insufficient oxygen is likely to occur, resulting in incomplete combustion and the production of carbon monoxide, which is harmful to humans.

3. Risks of raw materials and other products in ethylene glycol production

The main ethylene glycol production unit of Shanghai Petrochemical includes multiple units such as ethylene oxidation reaction and ethylene oxide absorption, which can adjust the output of ethylene glycol and ethylene oxide according to demand.

The current news reports are about the explosion happening in the device area, so theoretically there won't be any of the above problems. However, if the explosion is too severe and involves the production equipment, it may not be a good thing.

4. Danger of explosion itself

This is a risk brought by all explosions. The shock wave and various splashes it brings can easily cause casualties.

Currently, news reports say that an employee of Shanghai Petrochemical suffered a minor arm abrasion and a driver of a third-party transport vehicle died. It is estimated that the explosion itself was most likely the cause.

Overall, based on the limited information currently available, the Shanghai Petrochemical explosion should have little impact on ordinary local residents.

03. Why does Shanghai Petrochemical produce ethylene glycol?

So why does Shanghai Petrochemical produce ethylene glycol? This is related to ethylene glycol, an important industrial raw material.

As mentioned above, ethylene glycol itself can be used as a solvent, antifreeze agent, and raw material for synthetic polyester, so it has a wide range of uses in industry. Basically, many chemical plants are producing ethylene glycol. Shanghai Petrochemical is also an important ethylene glycol production enterprise.

According to news reports, the 380,000 t/a ethylene glycol unit of Shanghai Petrochemical Company has introduced the technology of the American Scientific Design Company. The main unit includes multiple units such as ethylene oxidation reaction and ethylene oxide absorption, which can flexibly adjust the output of the two main products, ethylene glycol and ethylene oxide, according to market conditions. Most of the equipment is domestically produced, and the unit consumption, energy consumption and product quality of the unit are at the leading level.

In addition, Shanghai Petrochemical Research Institute is also developing new ethylene glycol synthesis technology. Traditional ethylene glycol is produced by the petroleum route. The entire process is an ethylene production process, which consumes a large amount of ethylene resources. Therefore, Shanghai Petrochemical Research Institute has developed a complete set of technology for producing ethylene glycol from synthesis gas.

Finally, although chemical explosions are common, there are often fatal cases as reported in the Shanghai Petrochemical Safety Report.

But I personally think that chemical companies should not assume that frequent deaths are inevitable. They still need to strengthen safety production.