cement industry is no longer an ideal vision, but an urgent task in real life. In mid-January
2024, the Ministry of Ecology and Environment and other five departments jointly issued the Opinions on Promoting the Implementation of Ultra-low Emission in the Cement Industry, with the main objectives: by the end of 2025, significant progress will be made in key areas, and 50% of the cement clinker production capacity will be transformed. Large state-owned enterprise groups in the region will basically complete the transformation of organized and unorganized ultra-low emission; by the end of 2028, cement clinker production enterprises in key regions will basically complete the transformation, and 80% of the cement clinker production capacity in the whole country will be transformed.
Under the condition that the reference oxygen content is 10%, The hourly average emission concentration of particulate matter, sulfur dioxide and nitrogen oxides in the waste gas from the cement kiln and the waste heat utilization system at the kiln tail shall not be higher than 10 mg/m3 , 35 mg/ m3, 50mg/m3。
Whether it is the requirement of ultra-low emission value or the time node, it is not a small challenge for the cement industry, especially in the current extremely severe situation, to find a path of ultra-low emission transformation with both effect and benefit is the top priority of cement enterprises.
Judging from the current situation, the ultra-low emission transformation of dust and sulfur dioxide is basically no problem, the difficulty lies in the ultra-low emission transformation of nitrogen oxides, cement enterprises need to carefully select their own denitrification technology route according to their own production line characteristics, geographical location, resource conditions and other factors, in order to ensure environmental protection standards at the same time. To maximize economic and social benefits.
China Cement Network has learned that Suzhou Shijing Technology Co., Ltd. (Hereinafter referred to as "Shijing Technology"), which is famous for its "LCR denitrification technology" in the cement industry, has actually made great achievements in the field of "SCR denitrification technology".
"At present, cement SCR denitrification technology is mainly divided into high temperature and high dust SCR denitrification, high temperature and medium dust SCR denitrification, high temperature and low dust SCR denitrification, and medium temperature and medium dust SCR denitrification." Relevant person in charge of Shijing Science and Technology said that the above methods have their own advantages and disadvantages, but SCR denitrification with high temperature and dust has the characteristics of less equipment, easy arrangement, less system resistance, less air leakage, low maintenance and operation costs, and less investment, so it is also favored by many cement enterprises.
The most important thing is that in the face of the difficulty of "catalyst blockage and poisoning risk in high temperature and high dust SCR denitrification", Shijing Technology also has a "killer's mace".
According to the above-mentioned person in charge, Shijing Science and Technology focuses on avoiding catalyst blockage and poisoning in the design of source and equipment selection. Each project will test the flue gas composition parameters at C1 outlet, and the dust at C1 outlet is required to be less than 120g/ m3 (more than 120g/m3 requires dust reduction transformation). In terms of
catalysts, domestic professional suppliers are used, and the composition of raw materials exported from C1 is tested. More Reasonable and suitable catalyst is selected according to the influence of factors such as different raw meal compositions, flue gas temperature, SO2 , dust concentration of flue gas, alkali metals (and alkaline earth metals) in fly ash, heavy metals in fly ash, etc., and the catalyst mainly adopts 11/13 holes. Olves the problems of easy blockage, poisoning and failure of the traditional catalyst, optimizes the flow rate in the holes of the catalyst, and reduces the risks of dust accumulation, blockage and abrasion.
Shijing Technology also adopts a unique ash removal technology. Through the coupling of rake soot blower and sonic soot blower, the height of the soot blower nozzle is accurately designed to ensure the uniform and stable distribution of the flow field on the surface of the catalyst, so as to solve the problem of cement dust removal stably and reliably.
Each project will also use CFD fluid simulation to simulate and analyze the flow field of the reaction tower to demonstrate the feasibility and rationality of the scheme. The diversion uniform distribution plate and rectifier grid of Shijing Technology will be used to ensure the uniform distribution of flue gas and the uniform and stable flow field. Through the above measures, catalyst blockage and poisoning can be avoided.
From the practical application of cement enterprises, we can also get a glimpse of the denitrification technology effect of Shijing Technology. The kiln tail flue gas SCR denitrification transformation project of Guangling Cement Co., Ltd. contracted by Shijing Science and Technology was put into operation in March 2022 and reached the production standard. The system runs steadily, and the NOx emission concentration at the outlet is less than 35mg/Nm3 . Ammonia escape at outlet < 3.5mg/Nm3 , pressure drop of SCR denitration system < 800Pa (actual operation 400-600Pa), temperature drop of SCR system < 8 ℃ (actual operation 4-6 ℃), Ammonia consumption of SNCR + SCR per ton of clinker ≤ 3.0 kg (actual operation ~ 2.68 kg/t. Cl), electricity consumption per ton of clinker ~ 1.15 kWh. The kiln tail flue gas SCR denitrification transformation project
of Guangling Cement Co., Ltd. was put into operation in September 2023 and reached the production standard, and the system operated steadily. Outlet NOx emission concentration < 35mg/Nm3 , outlet ammonia escape < 3.5mg/Nm3 , Pressure drop of SCR denitration system < 800Pa (actual operation 350-600Pa), temperature drop of SCR system < 8 ℃ (actual operation 3-5 ℃), ammonia water consumption of SNCR + SCR per ton of clinker ≤ 3.0 kg (actual operation ~ 2.03 kg/t. Cl), electricity consumption per ton of clinker ~ 1.09 kWh.
For the cement industry, only by grasping the historical change of ultra-low emission and actively embracing and leading the green revolution, can enterprises cross the current environmental storm and enter the fast lane of sustainable development. Shijing Science and Technology may add a lot of color to the green journey of the cement industry. How can
cement enterprises complete the transformation of ultra-low emission with quality and quantity under the extremely complex and severe market situation? On March 28-29, China Cement Network will hold the " 13th China Cement Industry Summit and TOP100 Award Ceremony " in Hangzhou, during which awards will be given to top 100 cement and supplier enterprises, and experts and scholars will be invited. China Railway and other construction units jointly discuss the new development trend of the cement industry in the future, and work together to create the future!
