EPC Project of 4500t/d Clinker Cement Production Line Project of South Cement Chongzuo Co., Ltd.

　　I. General profile

　　South Cement Chongzuo Co., Ltd. is a wholly-owned subsidiary of South Cement Group Co., Ltd. Its management, operation, technology, production and other personnel are mainly from other subordinate companies of South Cement Guangxi Co., Ltd.

　　On December 16, 2010, the Environmental Protection Department of Guangxi Zhuang Autonomous Region issued Reply To The Environmental Impact Report On The Site Change Project of 4500t/d Cement Production Line With Low Temperature Waste Heat Generation Energy Conservation and Environmental Protection Comprehensive Project of Guangxi Jianfeng Cement Co., Ltd. with the document GuiHuanGuanZi [2010] No.160, agreeing the construction of the project. On July 18, 2011, Guangxi Jianfeng Cement Co., Ltd. and South Cement Co., Ltd. signed an equity transfer agreement. On August 23, 2011, the owner of the project was replaced by South Cement Chongzuo Co., Ltd. On October 20, 2011, the Environmental Protection Department of Guangxi Zhuang Autonomous Region issued a document GuiHuanHan [2011] No. 1524, agreeing to change the owner of the project to South Cement Chongzuo Co., Ltd. on December 27, 2011, the Guangxi Zhuang Autonomous Region Industry and Information Technology Commission issued a document GuiGongXinYuanHan [2011] No.1862, agreeing to the change application of the owner and investment amount of the project.

　　The EPC contract for the project was signed on November 15, 2012, with the commencement date of April 11, 2013 (partial foundation treatment is completed, and some individual civil construction items can be carried out). The completion time of foundation treatment: June 8, 2014 (the last single workshop - limestone crushing workshop completes the land acquisition, which was delivered to the general contractor for construction). On March 6, 2015 ignition was done. On March 13, 2015, the feeding was successful in one time. In May 2015, the project was handed over to the owner. Under the effective management of South Cement Chongzuo Co., Ltd., not only the actual operation status exceeded the performance requirements, but also the main production benchmarking ranks at the front in the middle and long term of South Cement. Based on the actual production situation after being put into operation, the project won the first prize of the 20th Excellent Engineering Design Achievement Award of Building Materials Industry issued by China Building Materials Engineering Construction Association in 2016, and the first prize of the 10th Excellent Engineering General Contract Award of Building Materials Industry issued by China Building Materials Engineering Construction Association in 2017.

　　II. Main technical difficulties and remarkable features

　　1. The project involves foundation treatment (foundation grouting and dynamic compaction), which is highly required by the owner. In addition to the general contract, South Cement Chongzuo Co., Ltd. and Nanjing Kisen International Engineering Co., Ltd. have signed the construction contracts for foundation grouting and dynamic compaction projects respectively. The foundation treatment of the project is complex and there are many underground karst caves. According to the actual situation of the site, the supplementary drilling and grouting construction are carried out for many items, such as the preheater, limestone pre-homogenization yard etc. The construction procedure of foundation treatment of the project is complex, which affects the overall construction progress. For example, most of the civil engineering foundation of the sub-items will be delivered to the foundation grouting unit for construction after blasting and excavation, and will be returned to the civil engineering construction after the foundation grouting construction is completed; some sub-items will be delivered to the foundation drilling construction after the foundation dynamic compaction construction is completed. The company leader in charge and the chief engineer of civil engineering have visited the site for many times. According to the drilling situation of the site foundation treatment, they have carried out design communication and jointly determined the design scheme, and finally completed the foundation treatment work scientifically and reasonably, and achieved good results.

　　2. Burning system

　　①The project adopts high solid gas ratio cyclone preheater + online calciner as raw meal preheating and decomposing equipment. In the projects of the same scale, the high solid gas ratio of preheater and reactor is realized by using cross flow and non-reactive material external circulation, thus effectively improving the thermal efficiency and reaction efficiency of the system, and the XDL high solid gas ratio energy-saving calcination technology, which greatly reduces the heat consumption of clinker, is the first at home and abroad. Under the condition of high solid gas ratio, the emission of SO2, NOx and other pollutants is greatly reduced. At the same time, the volume of high solid gas ratio preheater and calciner is smaller than that of ordinary preheater and calciner, but it is more efficient. Under normal production, the temperature of exhaust gas at the outlet of C1 cyclone of preheater is ≤270℃, and the system resistance is ≤5900pa.

　　② The rotary kiln system of this project is the first two-support rotary kiln independently developed and used by our company, which is of great significance for the company to develop market and establish public praise.

　　③The main features of FLSmidth grate cooler with middle roller crusher: crushing large materials by the roller crusher in the middle of the cooler, and further cooling on the second stage grate bed, which greatly reduces the temperature of clinker out of the cooler; through the MFR air volume self-balancing valve in the air chamber, the air supply in each area of the grate bed can be realized on demand, and the cooling efficiency can be improved. The whole grate bed does not move, and materials are transported by cross bar, so that no leakage of materials can be realized and the maintenance workload is small.

　　3. Prestressed silo structure technology is adopted in the design of raw meal homogenization silo and clinker silo of the project. After the prestressed technology is adopted, the quantity of ordinary reinforcement in the silo wall is greatly reduced, and the amount of concrete is reduced, which not only saves the project cost, but also improves the safety and durability of the structure, and at the same time, it can eliminate the hidden danger of quality and safety accident of silo collapse caused by the decrease of bond force between concrete and reinforcement caused by the dense reinforcement.

　　III. Main production and operation condition

　　After the 4500t/d production line of South Cement Chongzuo Co., Ltd. was officially put into commercial operation, the average clinker output of the kiln system has been maintained at 5850~6050t/d, the maximum monthly average output is 6300t/d, the average standard coal consumption of clinker is 99~101kg/t-cl, the 28d compressive strength of clinker is ~62MPa, the qualified rate of f-CaO control ≤1.5% in clinker is not less than 90%, the average power consumption of clinker from limestone crushing to the top of clinker silo (including limestone long belt conveying) is ~52.6kWh/t-cl, the air temperature at the C1 outlet of preheater is ~ 270℃, and the negative pressure at the outlet is ~5900Pa. The average power consumption of cement from the bottom of clinker silo to cement packaging/bulk delivery is ~32.5kWh/t-ce, among which the power consumption of grinding process is ~28.8kWh/t-ce.