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Our company’s original design capacity was 60 kt of synthetic ammonia per year, with the final product being **. After nearly 10 years of technological upgrades, the synthetic ammonia production capacity has been increased to 100 kt/year. Most of the production equipment, including gas generation, compression, and synthesis units, is capable of producing 120 kt of synthetic ammonia per year; the main bottleneck lies in the purification process. In the purification system, after being modified with medium-temperature shift and sulfur-resistant low-temperature shift units, and when combined with existing low-temperature shift and methanation (diumethanation) units, it meets the conditions for increasing production. The production bottlenecks lie in desulfurization and decarbonization. After conducting research, the company decided to carry out technical upgrades for desulfurization and decarbonization. The goal is to fully utilize the capacity of existing equipment, so that the ammonia synthesis system can achieve an annual production volume of 120 kt. This will enable both the ammonia processing system (130 kt/a** and 40 kt/a of urea) to operate at full capacity, thereby reducing costs, increasing profits, and ensuring a competitive advantage in the market. After thorough investigation and comparison, it was decided to collaborate with the Nanhua Research Institute by utilizing its patented technology—the low-heat-source variable-pressure regeneration process. This process is a pressure-regulated regeneration process developed to adjust the temperature, pressure, and composition of synthetic ammonia feed gas with relatively low shift pressure, using a low-heat supply source. The existing thermal potassium alkali CO2 removal process is modified by adopting a variable-pressure two-tower regeneration process in the solution regeneration system, which consists of a pressurized flash section and a pressurized stripping section in a pressurized regeneration tower, an atmospheric-pressure stripping tower, a subsonic injector, and a lean liquid flash tank. This approach makes use of the heat carried in by the shift gas to reduce the heat required for solution regeneration, thereby decreasing the amount of steam that needs to be supplied from outside – or even eliminating the need for external steam supply. Achieve the goals of energy conservation, reduced consumption, and increased production. After determining the process direction, the existing equipment is modified. The currently in-use CO2 regeneration tower was modified into a pressurized regeneration tower; an atmospheric-pressure regeneration tower and a lean liquid flash tank were built using existing equipment, and injectors and steam boilers were added. The specific process is as follows. 1 Raw gas stream: The shift gas with a pressure of approximately 2.04 MPa and a temperature of 160°C, produced in the sulfur-resistant low-temperature shift reactor, enters the medium-temperature boiling unit at the bottom of the pressure regeneration tower. After boiling the lean liquid, it proceeds to the shift gas heat exchanger, where it heats the gas obtained from the shift dehydration process. Subsequently, cooling, separation, and moisture removal are carried out for desulfurization. The temperature of the gas after degassing is around 45°C; after heat exchange in the shift gas heat exchanger, this temperature rises to about 90°C. The gas then enters the primary alkali scrubbing tower, where it comes into counter-current contact with the potassium alkali solution that enters the tower at its top and middle sections. As a result, the CO2 content in the outlet gas drops below 2.0%, and the gas is sent to the low-pressure shift system via an alkali separator. After passing through the low-temperature gas heat exchanger, the low-temperature gas is sent to the low-temperature gas boiler at the bottom of the pressure regeneration tower (with a CO2 content of about 4%). The temperature of the gas after boiling the lean liquid is around 120°C; this gas then enters the secondary alkaline scrubbing absorption tower, where it comes into countercurrent contact with the cold and hot lean liquids entering the tower from its top and middle sections to absorb CO2. The CO2 content in the outlet gas is reduced to below 0.2%. After cooling and separation, the gas exits the decarburization section. 2 Alkali wash process: The absorbed rich liquid coming out of the bottom of the primary alkali wash absorption tower enters the flash section at the top of the pressurized regeneration tower. After flashing, the solution is divided into two parts; most of it is sent via pipelines to the stripping section and the boiler at the bottom of the atmospheric pressure regeneration tower, where it is further desorbed to form a semi-poor liquid, while a smaller portion flows through the downcomer in the liquid collection tray of the rich liquid flash section into the stripping section and the boiler at the bottom of the pressurized regeneration tower, thereby being fully regenerated into a poor liquid. The lean liquid, at a pressure of 0.24 MPa and a temperature of 120°C, exits the tower and enters the lean liquid flash tank through pipelines. The steam generated by flashing is fed to the bottom of the atmospheric pressure regeneration tower for the stripping and regeneration of the semi-lean liquid. After flashing, the temperature of the lean liquid drops to 105°C; it then enters the lean liquid pump. After being pressurized, it is divided into two streams: one stream goes directly to the middle section of the secondary alkali washing absorption tower ； The other solutions enter the upper part of the secondary alkali washing absorption tower after being cooled by the potassium-alkali liquid cooler. The absorption rich liquid coming from the bottom of the secondary alkali scrubbing tower is pressurized by a transfer pump and then sent to the middle section of the primary alkali scrubbing tower ； The semi-depleted liquid with a temperature of about 100°C, coming from the bottom of the atmospheric pressure regeneration tower, is pressurized by a semi-depleted liquid pump and then fed into the top of the primary alkali scrubbing absorption tower. In the 3 CO2 gas process, the regenerated gas with a pressure of 0.18 MPa at the top of the pressurized regeneration tower is used as driving gas to enter a subsonic ejector, which in turn draws in the regenerated gas coming from the top of the atmospheric-pressure regeneration tower. This helps to maintain a slight positive pressure of 0.102–0.104 MPa at the top of the atmospheric-pressure regeneration tower. All the regenerated gas exiting the ejector passes through a CO2 waste heat recovery unit and a separator before being vented (with part of it being used as feed gas for urea production). In this process, although the temperature of the shift gas, which serves as the main heat source for the solution, is only 160°C with a water vapor content of 28% alone – a condition that differs significantly from those in typical foreign processes – the use of two regeneration towers to create pressure and temperature differences enables full utilization of the heat contained in the process gas. Additionally, the lean liquid flash tank can produce approximately 6 tons of steam per hour for the regeneration of the semi-lean liquid. The suction effect of the ejector also increases the desorption drive force in the atmospheric-pressure regeneration tower, thereby reducing the amount of steam required for stripping and significantly lowering the heat consumption associated with solution regeneration. 4 Process Characteristics By summarizing the production performance of our company over the past 8 months since the adoption of this technology, several characteristics can be identified. First, production capacity has increased significantly. Before use, the four units (with a capacity of 8,000 m3/h each) operated stably, while the five-unit setup was also functional; however, production volume often decreased due to poor alkali washing performance, resulting in very unstable operation ； After use, production remains stable; there has never been any reduction in output due to alkali washing requirements, and it can be used in six-machine production setups. Second, it achieves significant energy savings and reduced consumption. The steam consumption per ton of ammonia was 4.2 t before use, and it dropped to 3.0–3.2 t per ton of ammonia after use. As can be seen from the characteristics of this process, the heat consumption for solution regeneration is significantly reduced; with an increase in production capacity, the amount of steam required from external sources is greatly decreased. Moreover, since the circulation volume remains constant, the electricity consumption does not increase, and the amount of circulating water used also stays roughly the same. Third, production stability improves, and operational difficulty decreases. Judging from the current production situation, the production of five and a half machines is running very smoothly at present. Furthermore, although the addition of the low-heat-source voltage-regulated regeneration process has complicated the purification process and increased the operational difficulty of this section, overall, the overall operational difficulty has decreased as production has become more stable. It is worth mentioning that this technology was implemented, put into use, and showed results in the same year, with a successful first operation. Since it was started, this system has not experienced any failures. In summary, our company has adopted the low-heat-source variable-pressure regeneration process technology to upgrade the decarburization system. By making full use of the existing decarburization equipment and tapping into the potential of the current facilities and utility systems, it has been possible to increase production capacity, achieve energy savings and reduced consumption, ensure stable operation, and improve the efficiency of decarburization, all with minimal investment. · Summary of the operation of high-pressure alcohol alkylation process · Comparison of conversion processes and the application of medium-low-low processes in our company · Summary of 200 cases of full low-temperature conversion process application (III) – Sulfation reaction of Co-Mo-K series sulfur-resistant conversion catalysts · Analysis of the commissioning and operation of the cold box and expander in the second phase of Zhonghai Chemical · Analysis of the causes of failure and countermeasures for T102 desulfurization agent · No records available for now