【Haichuan’s Insight】Reduced the startup time of ammonia synthesis plants by a full 48 hours – a truly brilliant idea”

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Recently, at the event held by Jilin Petrochemical Company to announce awards for reasonable suggestions, Liu Weili, a worker from the synthetic ammonia production unit of the company’s fertilizer plant, received his award certificate. A year ago, a \"genius idea\" he proposed was successfully implemented, providing an \"acceleration\" for starting up the plant and reducing the time required to get the ammonia synthesis plant up and running by a full 48 hours. The ammonia synthesis workshop where Liu Weili works serves as the base for utility services and raw material supply at Jilin Petrochemical Company; it is crucial for ensuring a steady supply of hydrogen as well as for the operation and efficiency of various downstream processing units. How to enable the plant to restart quickly and steadily after the nearly 30-day annual maintenance has been a concern for process engineers over the years. If there is a knot, it must be untied, especially when it comes to matters that affect efficiency. As the deputy workshop director, Liu Weili was constantly busy like a top: working overtime, holding meetings, conducting research, gathering information, formulating plans – only to discard them all and start over again... Eventually, he led his colleagues to find a solution by repeatedly calculating the startup times for each process, thereby determining the optimal order in which to carry out those processes. In the past, for the airtightness tests before starting up the gasification furnace, it was necessary to wait until the air separation unit had produced qualified oxygen and nitrogen before proceeding with the tests. By connecting an external high-pressure nitrogen source, it is possible to proceed with both the air separation unit startup and the gasifier’s airtightness testing simultaneously, thereby **reducing the startup time**. “The new air separation unit has a nitrogen source! ”Liu Weili immediately thought of the new air separation unit. Although a gas source is available, the pressure level of 4.0 Mpa is far from sufficient to meet the device’s requirement of 7.0 Mpa; therefore, another nitrogen compressor is needed. Initially, it was planned to use the decommissioned compressor, but after conducting a thorough inspection, it was found that the problems involved were much more complex than expected. Compressors of such high pressure levels are not only rare in fertilizer plants, but also scarce throughout the entire company; let alone those that are already out of use. “What to do? With costs being so tight these days, any amount over 500,000 dollars requires approval from the corporate group; it’s definitely not possible to make such a purchase. ”During that time, Liu Weili dreamed about where to find a suitable compressor. “If I really can’t think of it, I’ll just look around. ”Upon examination, a solution was indeed found – after checking the equipment in use, the oxygen compressor in the nitric acid production unit came to Liu Weili’s attention: the outlet pressure was 7.0 Mpa, and the outlet flow rate was 1000 m3/h. “With the same pressure but a different medium, is it possible to introduce nitrogen into the oxygen compressor and solve the problem by changing the medium delivered by the compressor? ” A brilliant idea flashed through Liu Weili’s mind. To determine whether the idea was feasible, Liu Weili contacted compressor manufacturers, and the answer was yes. Full of enthusiasm, Liu Weili took immediate action and entrusted a design institute to handle the project coordination. They effectively isolated the oxygen pipeline leading to the high-pressure reactor in the nitric acid production unit by installing blind flanges; the oxygen inlet pipeline was also isolated using blind flanges. Additionally, blind flanges were installed on the pipeline that connects the gasifier in the ammonia synthesis unit to the nitrogen supply from the air separation unit. A buffer tank was added at the inlet of the oxygen compressor, and a 2-inch high-pressure pipeline 2100 meters long was installed at the outlet of the compressor to deliver oxygen to the gasifier in the ammonia synthesis unit. After passing inspection, it was put into use. In June 2018, during the preparation phase for restarting the ammonia synthesis plant after maintenance, this project was put into formal implementation, and the overall restart timeline was advanced by 48 hours compared to the original plan. Calculated at the prices of that time, this \"speed increase\" alone allowed savings of 1.048 million yuan through the use of high-pressure steam. More importantly, it enabled products to be delivered 48 hours earlier, thereby creating the conditions for the three downstream production units to start operating, resulting in indirect savings of tens of millions of yuan. (Reporter Peng Bing, Correspondent Gao Xiaowei)