【Haichuan Safety Discussion】Compilation of Reactor Accident Cases and Safety Protection Measures
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In a broad sense, a reaction vessel is a stainless steel container in which physical or chemical reactions take place. The structural design and parameter settings of such containers are determined based on the requirements of different processing conditions. Design criteria, processes, testing, as well as manufacturing and acceptance procedures must comply with relevant technical standards, in order to enable the vessel to perform functions such as heating, evaporation, cooling, and mixing at various speeds, as required by the processing process. Pressure vessels must comply with the GB150 {Steel Pressure Vessels} standard, while atmospheric pressure vessels must adhere to the NB/T47003.1-2009 {Steel Welded Atmospheric Pressure Vessels} standard. Consequently, the pressure requirements during the reaction process also result in varying design requirements for the containers. Production must be processed, tested, and trial-operated in strict accordance with the relevant standards. Stainless steel reaction vessels vary depending on different production processes and operating conditions; as a result, their design structure and parameters differ, meaning that their structural formats vary as well. They are therefore non-standard container devices. A reaction kettle is a comprehensive reaction vessel, and its structural design, functional features, and attached accessories are determined based on the reaction conditions. From the initial feeding to reaction and then discharging, the predefined reaction steps can be carried out with a high degree of automation, allowing for strict control over important parameters such as temperature, pressure, mechanical controls (stirring, ventilation, etc.), and the concentrations of reactants/products during the reaction process. Its structure generally consists of a tank body, a transmission device, a stirring device, a heating device, a cooling device, and a sealing device. Corresponding auxiliary equipment: fractionation columns, condensers, water separators, collection tanks, filters, etc. The materials used for reaction vessels generally include carbon-manganese steel, stainless steel, zirconium, nickel-based (Hastelloy, Monel) alloys, and other composite materials. The reaction kettle can be made of stainless steel materials such as SUS304 and SUS316L. Mixers come in anchor type, frame type, paddle type, turbine type, scraper type, and combined types. The rotating mechanism can be equipped with cycloidal pinwheel reducers, continuously variable speed reducers, or frequency-controlled speed regulators, allowing them to meet the specific reaction requirements of various materials. Sealing devices can adopt sealing structures such as mechanical seals and packing seals. Heating and cooling can be achieved using structures such as jackets, semi-tubes, coils, and Miller plates. The heating methods include steam, electric heating, and heat transfer oil, in order to meet the requirements of various working environments that demand resistance to acids, high temperatures, wear, and corrosion. It can also be designed and manufactured according to the user’s process requirements.
At around 11:15 a.m. on October 15, 2019, an explosion occurred in a reactor at Guangxi Lankē New Materials Co., Ltd., located at No. 3 in the eastern section of the centralized industrial park in the northern part of Luchuan County. According to reports from the relevant authorities, the number of casualties has increased; the accident has resulted in 4 deaths and 7 injuries, 2 of whom are in serious condition. A working group from the Yulin Emergency Management Bureau has arrived at the scene and is handling the situation urgently. It is understood that at around 8:30 a.m., the company began trial production. The main raw materials used were phenol and formaldehyde, and phenolic resin products were produced through chemical reactions. Around 11:15, an explosion occurred in the reactor, resulting in casualties and property damage. The amount of raw materials and semi-finished products stored in the reactor was approximately 5 tons. The cause of the explosion and the extent of property damage are under investigation.
According to the joint investigation and analysis by relevant departments, the occurrence of this accident was directly related to production operation errors, in addition to certain issues with the quality of the production equipment. When phenol is added, the rapid introduction of a large amount of the basic substance sodium hydroxide causes intense chemical reactions inside the reactor, generating a large amount of heat and pressure rapidly, which results in the reactants bursting out through the lid and spilling over.
According to the Tianjin Emergency Management Bureau, at around 9:11 on March 12, in the synthesis of hydrocortisone workshop of Tianjin Jinjin Pharmaceutical Co., Ltd. located in the industrial zone of Zhangjiawo Town, Xiqing District, Tianjin, a worker fainted while entering a stainless-steel hydrolysis reactor containing dichloromethane to retrieve a sampling container. The workshop supervisor also fainted while entering the reactor to try to rescue the worker. Both were rescued and taken to the hospital for treatment, but they died despite efforts to save them. Based on preliminary investigation and analysis, the direct cause of the accident was that workers entered a confined space to carry out work without obtaining approval for such operations, nor was an oxygen level check performed, which led to poisoning and asphyxiation. The detailed causes of the accident are still under further investigation. On March 17, the Office of the Tianjin Work Safety Committee issued a report titled \"Notice on the ‘3·12’ Poisoning and Asphyxiation Incident at Tianjin Jinjin Pharmaceutical Co., Ltd.\" It stated that the incident revealed issues such as the company’s weak safety awareness, its failure to learn from similar incidents, poor management of operations in confined spaces, as well as chaotic safety management within the company. Additionally, local regulatory authorities failed to carry out adequate special inspections regarding safety in confined space operations, and safety supervision was insufficient
Reporters learned from the Guang’an Economic Development Zone that at around 6 a.m. today (October 22, 2018), an explosion occurred in a wastewater reactor at Guang’an Lier Chemical Co., Ltd. in the Xinqiao Industrial Park. The roof of a workshop covering approximately 20 square meters collapsed; no fire broke out, but 4 people were injured. Following the accident, the Guang’an Municipal Party Committee and the municipal authorities attached great importance to it, immediately activating the emergency response plan. They ordered the Guang’an Economic Development Zone, as well as agencies responsible for safety supervision, environmental monitoring, public security, and firefighting, to rush to the scene right away to carry out rescue and handling efforts. At present, the injured have received proper treatment and are none in life-threatening condition. The cause of the accident is under further investigation.
Reporters learned from the Guang’an Economic Development Zone that at around 6 a.m. today (October 22, 2018), an explosion occurred in a wastewater reactor at Guang’an Lier Chemical Co., Ltd. in the Xinqiao Industrial Park. The roof of a workshop covering approximately 20 square meters collapsed; no fire broke out, but 4 people were injured. Following the accident, the Guang’an Municipal Party Committee and the municipal authorities attached great importance to it, immediately activating the emergency response plan. They ordered the Guang’an Economic Development Zone, as well as agencies responsible for safety supervision, environmental monitoring, public security, and firefighting, to rush to the scene right away to carry out rescue and handling efforts. At present, the injured have received proper treatment and are none in life-threatening condition. The cause of the accident is under further investigation.
An explosion occurred during the maintenance of a reactor at a chemical plant in Shenze, Hebei, injuring a worker’s leg. The Paper, February 11, 2017 · Official account of The Paper. On the morning of February 11, a responsible official from the Publicity Department of the Shenze County Party Committee told The Paper (www.thepaper.cn) that at around 10 p.m. on the 10th, a reactor at the first production workshop of Huayun Hongye Chemical Co., Ltd. in Shenze County (i.e., a container used for physical or chemical reactions) exploded during maintenance, resulting in injuries to a worker’s leg. The injured person is currently being treated in a hospital, and the cause of the accident is still under investigation. In the early hours of the 11th, a staff member from the Public Relations Department of the Shijiazhuang Public Security Bureau told The Paper that, according to available information, one person was lightly injured in the chemical plant explosion; the fire has now been brought under control. Further details will be released through official Weibo and WeChat accounts.
At around 3:20 a.m. today, an explosion occurred in a reactor in the dimethyl ether production workshop on the second floor of Jiu Tai Energy (Guangzhou) Co., Ltd., located in the Xiaohu Chemical Industry Zone in Huangge Town, Nansha District, Guangzhou, triggering a fire. Thanks to the prompt intervention by local authorities including the public security and fire departments, the fire was completely extinguished by 6:40 a.m. The incident resulted in two people suffering minor injuries; no one died. The chemical plant where the incident occurred was engulfed in flames, with large amounts of thick smoke rising into the air. A fire broke out on the second floor of the factory building belonging to Jiu Tai Energy (Guangzhou) Co., Ltd. in Nansha District, Guangzhou, around 3 a.m. on Tuesday, April 3. After more than three hours of effort by the local firefighters, the fire was brought under control at around 6:40 a.m., and no injuries were reported as a result of the incident. The relevant departments are investigating the cause of the fire, while environmental protection agencies in Nansha District are stepping up monitoring of the environment at the scene.
Lessons from a Reactor Leakage Incident: Course of the Incident Around 10:55 p.m. on April 27, 2005, a chlorine leak occurred in a reactor (drip tank) at a chemical plant, resulting in the death of 2 operators; the other operators were not injured as they managed to escape by jumping down from an operating platform over 2 meters high. This reactor lacks a factory nameplate or accompanying documentation, and its design parameters are unknown; the inner cylinder and jacket of the reactor are made of carbon steel. The medium used in the inner cylinder is hydrogen chloride and chlorine gas. Usage parameters: The pressure in the inner cylinder is at atmospheric pressure ； The jacket medium is steam; the operating pressure in the jacket is around 0.4 MPa. Within the operating temperature range, the temperature inside the inner cylinder is ≤200°C, while that in the jacket is ≤165°C. The inner cylinder and jacket head are of oval shape, the support type is suspension type, the volume is 1000 liters, and the inner cylinder is lined with enamel; inspections have shown that the enamel is in good condition. The reaction structure is shown in Figure 1. As a pressure vessel, this equipment has not been inspected by the special equipment inspection authorities since it was put into use.