Prevent the advancement of the gate to reduce the flash explosion accident

The dangers of hydrogen peroxide production processes have been the focus of the industry. Experts stressed that advance prediction, scientific prevention, advance prevention of safety production, and establishment of an effective safety prevention and control system can fully guarantee the safe and stable operation of hydrogen peroxide production equipment. At the 2013 Peroxide Industry Symposium held recently, experts focused on the safety of hydrogen peroxide production.

It is understood that many sets of domestic hydrogen peroxide production equipment have experienced flash explosion accidents in equipments such as tanks, oxidation towers, and oxidizing liquid pipelines. Therefore, how to do a good job of prevention and reduce flash accidents is the focus of safety work in hydrogen peroxide production.

Manage raw materials: safety first step

Static electricity is the main culprit in the flashover process of hydrogen peroxide production. Therefore, it is necessary to pay attention to prevent static electricity, do a good job of electrostatic grounding of equipment and pipelines, and promptly remove static electricity that may be generated, so that the system does not reach the energy required for flash explosion.

Chen Jun, an engineer at Jining Weida Fine Chemical Co., Ltd., believes that effective preventive measures can prevent flash explosions. You can start by controlling the purchase of raw materials. Manufacturers should analyze the component content and flash point of heavy aromatics. Under the premise of ensuring the quality of heavy aromatics, the purchase of heavy aromatics with high flash point is used to control safety from the source.

The quality control of the resins used in the production of hydrogen peroxide is also very important. After the resin is purified for a period of time, the adsorption and exchange values ​​are close to saturation, and a small part of the resin is oxidized and pulverized by contact with the aqueous solution for a long time in the purification process, and the resin is regenerated.

Zhang Ge, technical director of Hegel (Dalian) Biochemical Technology Co., Ltd., reminded enterprises that the recycled cleaning resin must be cleaned, and the conductivity of the resin after treatment should be no more than 30us/cm. Otherwise, after the alkali molecules remaining in the resin group are in contact with the acidic aqueous solution of hydrogen peroxide, the liberation heat reaction occurs immediately, and there is a risk of an explosion accident. The cleaning and recycling of the resin is very important. It is not only related to whether it can produce qualified products during the purification process, but also related to safe production. This work must be carried out by professional staff to ensure the production process. safety.

Temperature control: the key to safety

Experts stressed that the temperature of hydrogen peroxide in the process of purification production is related to the safety of the operating staff and the safety of production equipment. In the event of an explosion in a hydrogen peroxide unit, 95% of the line's temperature is above 60 °C. In the open parking phase, the process parameters fluctuate greatly, and it is easy to have a flash explosion accident. Therefore, the control of the process parameters during on-off should be strengthened to control the temperature of the oxidation system at a lower temperature (<40 °C). Even if there is static electricity (ignition source), the temperature cannot reach the flash point of the flammable mixture. A flash explosion occurred.

According to Zhang, the temperature change of the resin in the ion exchange work on the production line and the aqueous hydrogen peroxide solution is generally 0.5 ° C to 2.5 ° C. The temperature data in this range indicates that the resin on the production line is qualified, so the temperature of H2O2 should not change more than 3 °C on the production line. If it is greater than 3 °C, it means that the H2O2 aqueous solution has been separated from the resin and it will occur. Explosion accident. At this time, production should be stopped immediately, and the H2O2 aqueous solution and resin in the equipment should be immediately removed, and the qualified resin must be replaced for production to ensure the safety of the production process.

Zhang average pointed out that temperature is an important factor in production safety, and can not make a slight mistake. The observation of equipment pressure data is also very important. Once the pressure data reaches the pressure of more than 30% of the equipment design pressure data, the parking program has not been started. Stop immediately to handle pressure failure until the pressure is relieved.

　　

Feed concentration: key control object

Experts said that the production of high concentrations of hydrogen peroxide also poses a hidden danger to system safety, and this security risk is often malignant once it breaks out. With the improvement and introduction of the hydrogen peroxide process route, the production capacity of palladium catalyst and working fluid is improved, and the concentration of rare hydrogen peroxide can directly reach 40% to 46%. This increases the feed concentration of the evaporation and rectification systems.

Zheng Guoyu, a senior engineer at China Tianchen Engineering Co., Ltd., said that at the same technical level product concentration, the higher the feed concentration, the greater the proportion of technical grade products in the feed amount. The technical grade product is the remaining liquid at the bottom of the falling film evaporator. All the impurities brought in by the rare product are accumulated here, although the concentration of these impurities is reduced by increasing the circulation amount, but the technical grade ratio is too large, and the evaporation amount In the case of low, the amount of circulation cannot be increased indefinitely. Therefore, when producing 60% to 70% of the product, the rare product entering the concentration system must be purified to remove metal and non-metal ions such as iron, tin, phosphate, sulfate and organic carbon in the liquid to ensure the system. Safety.

When the concentration of hydrogen peroxide entering the evaporation system is high, the safety impact on the concentration system is not directly reflected, but is caused by the insecurity caused by other parameters, so it is often omitted. In particular, the production of 50% hydrogen peroxide products, if the concentration of hydrogen peroxide in the feed liquid is 40% to 46%, the concentration system products are almost all technical grade products, the evaporation is very small, the chemistry generated in the distillation column Level products sometimes fail to meet product specifications. At this time, it is particularly important to note that the falling film evaporator easily exceeds the limit heat load and produces a dry pipe phenomenon, which causes decomposition of hydrogen peroxide and explosion.

Zheng Guoyu believes that when the concentration of dilute hydrogen peroxide is high, the technical grade product is transferred to the bottom of the rectification column. Because the pressure at the bottom of the rectification column is lower than the pressure at the bottom of the evaporator, the boiling point is also reduced accordingly. The grade products are far from the danger zone.