Report on the flash explosion incident in the rotary lime kiln of Jiangsu Zhongshengyuan Toksun Energy Chemical Company

In accordance with the provisions of the Work Safety Law, the Regulations on the Reporting, Investigation and Handling of Work Safety Accidents (Decree No. 493 of the State Council), and the Implementing Measures for the Reporting, Investigation and Handling of Work Safety Accidents in the Autonomous Region (Decree No. 196 of the People’s Government of the Autonomous Region), the People’s Government of Turpan City established an investigation team for the “12·25” accident. Members of this team included officials from the city’s Work Safety Supervision Bureau, Public Security Bureau, Human Resources and Social Security Bureau, Commission for Discipline Inspection and Supervision, Trade Union, as well as the People’s Government of Toksun County and its relevant departments. Under the guidance of the Emergency Management Department of the Autonomous Region, they conducted an investigation into this accident, and two experts were hired to assist in determining the causes of the accident. In accordance with the principles of \"not letting go until the issues are resolved\" and \"being scientific and rigorous, acting in accordance with laws and regulations, seeking truth from facts, and focusing on practical results\", the accident investigation team determined the course of events, causes, and casualties resulting from the accident through on-site inspections, evidence collection, document review, and expert analysis. It identified the nature of the accident and the responsibilities involved, and put forward recommendations for dealing with the relevant responsible entities and individuals, as well as preventive and corrective measures.

In accordance with the provisions of the Work Safety Law, the Regulations on the Reporting, Investigation and Handling of Work Safety Accidents (Decree No. 493 of the State Council), and the Implementing Measures for the Reporting, Investigation and Handling of Work Safety Accidents in the Autonomous Region (Decree No. 196 of the People’s Government of the Autonomous Region), the People’s Government of Turpan City established an investigation team for the “12·25” accident. Members of this team included officials from the city’s Work Safety Supervision Bureau, Public Security Bureau, Human Resources and Social Security Bureau, Commission for Discipline Inspection and Supervision, Trade Union, as well as the People’s Government of Toksun County and its relevant departments. Under the guidance of the Emergency Management Department of the Autonomous Region, they conducted an investigation into this accident, and two experts were hired to assist in determining the causes of the accident. In accordance with the principles of \"not letting go until the issues are resolved\" and \"being scientific and rigorous, acting in accordance with laws and regulations, seeking truth from facts, and focusing on practical results\", the accident investigation team determined the course of events, causes, and casualties resulting from the accident through on-site inspections, evidence collection, document review, and expert analysis. It identified the nature of the accident and the responsibilities involved, and put forward recommendations for dealing with the relevant responsible entities and individuals, as well as preventive and corrective measures.

I. Basic Information (I) Basic information of the unit where the accident occurred 1. Jiangsu Zhongshengyuan Technology Co., Ltd. It was registered on June 28, 2002, with its registered address at No. 68, Shengtai Road, Jiangning District, Nanjing City, and its unified social credit code is XXX. The legal representative is Shen Hao, with a registered capital of XXX ten thousand yuan. Business scope: Research and development in calcination engineering technology, technical services ； Sales, installation, and after-sales service of mechanical equipment and electromechanical devices. Safety license number: (Su) JZ Safety License No. XXX; valid from May 27, 2018, to May 26, 2021; the scope of the license covers construction work. Construction enterprise qualifications: Grade 3 specialized contracting for building mechanical and electrical installation works, Grade 3 general contracting for metallurgical engineering construction; certificate number: XXX. The engineering design qualification is Class B for the building materials industry; certificate number: XXX, valid until August 7, 2020. 2. Tuoxun Energy Chemical Co., Ltd. It was registered on October 19, 2012; its registered address is on the south side of the third auxiliary road in the industrial park of Toksun County, Turpan City, Xinjiang, and its unified social credit code is XXX. The legal representative is Zhang Qunrong, with a registered capital of XX billion yuan. Business scope: Sale of chemical products (excluding hazardous chemicals) and building materials ； Calcium carbide production and sales ； Electricity production and sales ； Thermal power production and sales ； Cement production and sales ； House rental. Work Safety License Number: XXX; Validity period: from July 28, 2016, to July 27, 2019. 3. Dahua Group Beijing Zhongda Lian Consulting Co., Ltd. It was registered on October 17, 1996; its registered address is Room 924, Building 3, 9th Floor, No. 18 Jianguomennei Street, Dongcheng District, Beijing, with a unified social credit code of XXX. The legal representative is Du Yonglin, with a registered capital of XXX ten thousand yuan. Business scope: Supervision and consulting ； Technology development, technical consultation, technology transfer, technical services ； Talent training ； Information consultation ； Construction supervision for electrical industry building installation projects, chemical industry building installation projects, and general industrial and civil building installation projects. It holds Class A qualifications for power engineering supervision. Qualification certificate number: XXX ； Class B qualification for supervision of municipal public works, Class B qualification for supervision of building construction projects, and Class B qualification for supervision of smelting projects; certificate number: XXX.

(II) Information regarding the 600t/d rotary lime kiln installation project: On September 25, 2017, Tuoxun Energy Chemical Co., Ltd. entered into an EPC general contract for the construction of a 600t/d rotary lime kiln with Zhongshengyuan Technology Co., Ltd. [Contract number: 3140GC1710-097]. On December 5, 2017, Toksun Energy Chemical Co., Ltd. signed a Supervision Contract for the 600t/d Rotary Lime Kiln Project of Toksun Energy Chemical Co., Ltd. with Dahuagroup Beijing Zhongdalian Consulting Co., Ltd. On December 13, 2017, Tuoxun Energy Chemical Co., Ltd. established a project team for the rotary lime kiln improvement initiative. He Pengfei, the deputy general manager of the company, served as the team leader, while Zhang Zhiqiang, the head of the project management department, acted as the deputy leader. The team members included Huang Jianzhang, the head of the production technology department, Cai Yuanxun, the head of the mechanical and power department, Wang Chao, the head of the safety and environmental protection department, as well as professional technicians from various relevant departments and workshops. Subsequently, the technical improvement project team for rotary lime kilns created a WeChat group for the rotary kiln project to facilitate communication and coordination, and added the project-related personnel from Zhongshengyuan Company and Dahuawa Company to this WeChat group. In March 2018, Zhongshengyuan Technology Co., Ltd. established an EPC general contracting project team for the 600t/d rotary lime kiln facility at Toksun Energy Chemical Co., Ltd., with Yu Mingzhu as the project manager. On October 15, 2018, Zhongshengyuan Technology Co., Ltd., in order to accelerate the progress of the EPC turnkey project for the rotary lime kiln, assigned Kuang Fanghui, the deputy manager of the engineering department, to go to the project site to oversee things. On November 17, Zhongshengyuan Technology Co., Ltd. assigned Huang Xinjing, a process tuning engineer from the R&D department, to the project site to be responsible for the tuning and commissioning of the rotary lime kiln. On November 23, project manager Yu Mingzhu left the rotary lime kiln project site and returned to Nanjing, not returning to the project site until December 25. Up to the time of the accident, aside from some industrial monitors, auxiliary equipment and facilities, auxiliary instruments, and certain components that had not yet been installed, the main mechanical and electrical equipment such as rotary kilns, air fans, gas compressors, high-temperature fans, raw material preheaters, gas preheaters, dust collectors, etc., along with their connecting pipelines, had been installed. The main instruments were in place, the key process parameters could be displayed properly in the control room’s DCS system, and the supply of water, electricity, and gas was normal.

II. Course of the accident and emergency rescue efforts (1) Course of the accident. In November 2018, the equipment for the rotary lime kiln was basically installed, and Zhongshengyuan Technology Co., Ltd. began to carry out debugging of the equipment. On November 22, Zhongshengyuan Technology Co., Ltd. submitted individual commissioning plans for the rotary lime kiln equipment to Toksun Energy Chemical Co., Ltd. and Dahuagroup Beijing Zhongdalian Consulting Co., Ltd., and these plans were approved. On November 23, Zhongshengyuan Technology Co., Ltd. carried out single-unit testing. On December 8, Zhongshengyuan Technology Co., Ltd. submitted equipment coordination and commissioning plans to Dahuagroup Beijing Zhongdalian Consulting Co., Ltd. and Tuoxun Energy Chemical Co., Ltd., which were approved. From December 15 to 24, Zhongshengyuan Technology Co., Ltd. carried out joint debugging of various subsystems. At 12:30 on December 19, Toksun Energy Chemical Co., Ltd. and Zhongshengyuan Technology Co., Ltd. held a production preparation meeting for the rotary lime kiln project, deciding to use gas to start up the kiln. At 17:06 on December 23, Kuang Fanghui, deputy manager of the Engineering Department at Zhongshengyuan Technology Co., Ltd., posted a message in the WeChat group of the rotary lime kiln project team titled \"Conditions Required for Ignition\", asking those who would be involved in the ignition process to study it. At 12:30 on December 24, He Pengfei, the deputy general manager of Toksun Energy Chemical Co., Ltd. and the person in charge of the rotary lime kiln project, held a summary meeting for the project team regarding the \"three inspections and four determinations\" process. At 19:40 on December 24, Toksun Energy Chemical Co., Ltd. and Zhongshengyuan Technology Co., Ltd. held a production preparation meeting for the rotary lime kiln project team; progress on the rectification tasks outlined in the “three inspections and four determinations” approach was reported, and a meeting minutes was prepared regarding the production preparation work. The meeting was chaired by He Pengfei, and it was decided that the kiln would be started up on December 25. On the afternoon of December 24, Zhongshengyuan Technology Co., Ltd. and Turpan Energy & Chemical Co., Ltd. continued to carry out defect-removal work on relevant equipment. The adjustment of the burner positions was completed at 1 a.m. on the 25th. At 9:30 on December 25, the personnel involved in the ignition process from Zhongshengyuan Technology Co., Ltd., Tuoxun Energy Chemical Co., Ltd., and Dahuahua Group’s Beijing Zhongdalian Consulting Co., Ltd., along with related support staff and construction workers, entered the site one after another to begin their work. Tuoksun Energy Chemical Co., Ltd. arranged for personnel to set up warning tapes at the site intersection. At 11:00, Wang Dong, the safety specialist from the Safety and Environmental Protection Department of Tuoxun Energy Chemical Co., Ltd., instructed the staff working in the rotary lime kiln to evacuate the area. At 12:13, Li Hui and Ma Fangwen, the gas tank inspectors in the rotary lime kiln workshop, followed the instructions of Wu Jingxiang, the assistant to the workshop manager, and Xu Yingming, the team leader in charge of the gas tanks, to inject nitrogen into the rotary lime kiln system in order to begin the gas displacement process, which was completed at 13:20. At 13:20, Wang Peng, the safety officer in the lime kiln workshop of Toksun Energy Chemical Co., Ltd., instructed Dou Yabo, an analyst from the laboratory, to take samples from sampling port No. 2 of the main gas pipeline at the entrance of the rotary lime kiln. Analyst Li Quanhui completed the sample analysis at 13:50, with the analysis result showing an oxygen content of 3.07%. At 13:25, Dou Yabo completed sampling at sampling port No. 1 of the gas pipeline at the rear end of the rotary lime kiln. Analyst Li Quanhui finished the sampling and analysis at 13:55, with the analysis showing an oxygen content of 1.76%. At 14:00, Zhongshengyuan Technology Co., Ltd. completed the installation of the flexible metal hose connecting the pipeline behind the flow control valve at the end of the gas pipeline to the burner of the rotary kiln. At 14:23, laboratory analyst Cheng Erlong completed the second sampling at Sampling Point No. 2 on the gas pipeline at the furnace head of the rotary lime kiln. Analyst Mi Xing finished the analysis of the sample at 14:38; the results showed that the oxygen content was 1.66%. At 14:53, Huang Xinjing, a process engineer at Zhongshengyuan Technology Co., Ltd., instructed Dai Taozhong, the material feeding operator in the lime kiln workshop of Toksun Energy Chemical Co., Ltd., to open the blind valve on the coal gas pipeline at the kiln inlet. At 14:57, Huang Xinjing instructed Dai Taozhong to activate an auxiliary combustion fan (air fan) to supply air into the rotary lime kiln, and it remained in operation until the accident occurred: the outlet pressure (PtOO6) was 4 KPa at 15:00, and the flow rate of the auxiliary fan (Ft006) was 1400 m³/h at 15:00, and these values persisted until 16:29. At around 16:00, Wu Jingxiang went to the control room and told Huang Xinjing that the gas had been delivered to the kiln head, and Huang Xinjing would be responsible for the subsequent operations. At 16:28, Huang Xinjing instructed Dai Taozhong to open the butterfly valve and the two control valves in sequence, setting the opening degree of each control valve to 50%. The 2# gas compressor began to supply gas to the rotary lime kiln. The gas pressure (PT004) at the flow control valve in front of the burner increased from 0 to 7.5 KPa, and then fluctuated between 4.8 KPa and 7.5 KPa. At 16:29, the pressure at the outlet of one of the combustion air fans rose to 9.6 KPa. From 16:30:11 to 16:30:14, Wang Haidong, director of the lime kiln workshop at Turpan Nenghua Co., Ltd., Wang Yongsheng, an inspection worker in the lime kiln workshop, and Su Fulong, deputy director of the same workshop, inserted torches into the furnace; immediately thereafter, a flash explosion occurred.

(II) Emergency rescue and post-incident handling: Upon receiving the report of the accident, the Turpan Municipal Party Committee, **, the Toksun County Party Committee, ** promptly activated the emergency response plan for work safety accidents. The top leaders and those in charge of relevant affairs at the municipal and county party committees rushed to the accident scene immediately. They led the key officials from departments such as the municipal public security bureau, the safety supervision agency, and the health and family planning commission, as well as experts from Turpan City Hospital, to the scene in order to coordinate emergency rescue efforts, implement safety measures, and visit the injured. The city and county promptly established joint task forces for medical treatment, prevention of secondary accidents, post-accident handling, accident investigation, and public opinion management, to carry out various tasks related to the accident in an orderly manner. To prevent other unforeseen situations, the accident command team instructed the enterprise to have professionals carry out gas replacement in the main gas pipeline running from the gas tank, through the main gas valve of the rotary kiln, to the quick-cut inlet valve of the rotary kiln, in order to avoid secondary accidents.

III. Causes of the accident and nature of the incident (1) Direct cause: Before ignition of the rotary lime kiln, gas and air were introduced into it, resulting in the formation of a mixed explosive gas throughout the entire rotary kiln system from the kiln inlet to the dust collector. When a torch was brought near the burner inside the kiln, an explosion occurred rapidly. (II) Indirect causes: 1. Zhongshengyuan Technology Co., Ltd.’s prepared \"Firing Plan\" and \"Requirements for Preparations Before Ignition\" contained defects; they did not specify the exact roles of the personnel responsible for directing the ignition and operation of the rotary lime kiln, which led to chaos in on-site command and management ； The professional technicians sent to oversee the ignition process made a mistake: they allowed gas and air to enter the rotary lime kiln before inserting the ignition torch into it ； The project manager assigned to the site was often absent, and personnel lacking safety management capabilities were assigned to oversee the project, resulting in a loss of control over safety management for the rotary lime kiln project. 2. Tuoxun Energy Chemical Co., Ltd. has a safety management system that exists only on paper and is not effectively implemented ； The system for identifying and addressing safety hazards is not effectively implemented, and the “three inspections and four determinations” process for fixing issues is not carried out properly ； The \"Firing Plan\" and \"Conditions Required for Ignition\" have not been approved ； The personnel involved in starting the furnace do not receive adequate pre-job professional training ； Without verifying and confirming the critical steps, the torch was placed into the rotary lime kiln. 3. Dahua Group Beijing Zhongdalian Consulting Co., Ltd. failed to fulfill its duties regarding safety supervision in production; it failed to identify the defects in the \"Firing Plan\" and the \"Conditions Required for Ignition\" submitted by Zhongshengyuan Company ； No effective action was taken to stop actions such as initiating the firing of the furnace before the project was completed in accordance with the design, as well as the chaotic on-site management.

III. Causes of the accident and nature of the incident (1) Direct cause: Before ignition of the rotary lime kiln, gas and air were introduced into it, resulting in the formation of a mixed explosive gas throughout the entire rotary kiln system from the kiln inlet to the dust collector. When a torch was brought near the burner inside the kiln, an explosion occurred rapidly. (II) Indirect causes: 1. Zhongshengyuan Technology Co., Ltd.’s prepared \"Firing Plan\" and \"Requirements for Preparations Before Ignition\" contained defects; they did not specify the exact roles of the personnel responsible for directing the ignition and operation of the rotary lime kiln, which led to chaos in on-site command and management ； The professional technicians sent to oversee the ignition process made a mistake: they allowed gas and air to enter the rotary lime kiln before inserting the ignition torch into it ； The project manager assigned to the site was often absent, and personnel lacking safety management capabilities were assigned to oversee the project, resulting in a loss of control over safety management for the rotary lime kiln project. 2. Tuoxun Energy Chemical Co., Ltd. has a safety management system that exists only on paper and is not effectively implemented ； The system for identifying and addressing safety hazards is not effectively implemented, and the “three inspections and four determinations” process for fixing issues is not carried out properly ； The \"Firing Plan\" and \"Conditions Required for Ignition\" have not been approved ； The personnel involved in starting the furnace do not receive adequate pre-job professional training ； Without verifying and confirming the critical steps, the torch was placed into the rotary lime kiln. 3. Dahua Group Beijing Zhongdalian Consulting Co., Ltd. failed to fulfill its duties regarding safety supervision in production; it failed to identify the defects in the \"Firing Plan\" and the \"Conditions Required for Ignition\" submitted by Zhongshengyuan Company ； No effective action was taken to stop actions such as initiating the firing of the furnace before the project was completed in accordance with the design, as well as the chaotic on-site management.

(III) Nature of the accident: Upon investigation, it was determined that the “12·25” accident was a relatively serious accident resulting from negligence in production safety. IV. Handling of Persons and Units Responsible for the Incident (I) Exemption from liability for certain persons 1. Yu Mingzhu, manager of the EPC general contracting project team for the rotary lime kiln system at Zhongshengyuan Technology Co., Ltd., who is in charge of all aspects of the project team’s work. He bore direct responsibility for the accident; given that he died in the accident, he is exempt from any further accountability. 2. Liu Chuangye, Deputy General Manager and Head of Safety at Toksun Energy Chemical Co., Ltd. He was responsible for the accident, but since he died in the accident, he is exempt from any further liability. 3. Zhang Zhiqiang, Head of the Project Management Department at Toksun Energy Chemical Co., Ltd., and Deputy Leader of the rotary lime kiln project. He is responsible for the occurrence of the accident, but since he died in the accident, he shall be exempted from liability. 4. Qiu Shaozhang, Chief Supervising Engineer of the supervision department for the rotary lime kiln project at Tuoxun Energy and Chemical Co., Ltd., assigned by Dahua Group Co., Ltd. He is responsible for the occurrence of the accident, but since he died in the accident, he shall be exempted from liability.

(II) Persons transferred to judicial authorities for criminal prosecution: 1. Huang Xinjing, process engineer assigned by Jiangsu Zhongshengyuan Technology Co., Ltd. to the rotary lime kiln project at Tuoxun Energy Chemical Co., Ltd. Suspected of the crime of major liability accident, transferred to judicial authorities for criminal prosecution. 2. Kuang Fanghui, Deputy Manager of the Engineering Department at Jiangsu Zhongshengyuan Technology Co., Ltd.; a mechanical and electrical engineer. He was assigned by the company to oversee the construction progress of the rotary lime kiln project, served as the head of the special team responsible for the joint commissioning of the rotary lime kiln, and was ultimately in charge of project management during the later stages of the project. Suspected of the crime of major liability accident, transferred to judicial authorities for criminal prosecution. 3. He Pengfei, Deputy General Manager of Toksun Nenghua Co., Ltd., and Team Leader of the Rotary Lime Kiln Project. Suspected of the crime of major liability accident, transferred to judicial authorities for criminal prosecution.