Based on the operation data of ?4.8m×74m rotary kiln, it briefly descrbes the measuring method of the clearance between the kiln tyre and the backing plate by measuring the thermal expansion and slippage, and the impact of clearance size on the operation of rotary kiln and its adjustment measures. Excessive clearance between the kiln tyre and the backing plate would easily cause the breakage and fall-off of the refractory bricks and shorten its service life, while too small clearance would easily cause uneven thermal expansion of the rotary kiln and result in the "necking" phenomenon, which would seriously affect the safe operation of the kiln. By strengthening the lubrication and maintenance, adjusting the thickness of the backing plate, replacing the backing plate, etc., the clearance between the kiln tyre and the backing plate could be ensured within a reasonable range, which reduce costs of kiln maintenance, and further improve the operation rate of the rotary kiln.

This paper systematically analyzes the research progress of typical CCUS technologies worldwide, including oxy-fuel combustion, chilled ammonia absorption, membrane separation, calcium looping technologies, etc. It focuses on the research outcomes of the Qingzhou Zhonglian oxy-fuel combustion coupled carbon capture demonstration project. The Qingzhou Zhonglian demonstration project achieved efficient carbon capture in cement production through full oxy-fuel combustion technology, overcoming key technical challenges such as high-oxygen concentration flame control, CO₂ enrichment concentration, and meal calcining rate under high CO₂ concentration conditions, through innovative methods such as graded oxygen supply and discrete dilution combustion, the energy consumption and cost of carbon capture have been significantly reduced. The research indicates that oxy-fuel combustion technology can increase the CO₂ concentration in flue gas to over 80%, laying a foundation for low-energy physical carbon capture. The successful operation of the Qingzhou Zhonglian demonstration project provides an important example for the industrial application of low-carbon technologies in the cement industry.

The heat transfer mechanism between cement clinker and air in a grate cooler was studied, and based on the actual operating parameters of a 5 000t/d cement clinker production line in China, the heat transfer process inside the grate cooler was numerically simulated using porous media theory. A physical and mathematical model of the grate cooler was established, and the temperature field, pressure distribution, and flow field distribution inside the grate cooler were numerically simulated using Fluent fluid calculation software. The relationship between the temperature of the middle air intake of the grate cooler and the thickness of the clinker layer was analyzed in detail. Based on the simulation analysis results, the positions of each air intake of the grate cooler and the distribution of air volume were reasonably arranged.

With the deepening of national carbon dioxide reduction work, the cement industry, as an important source of carbon dioxide emissions, has received widespread attention. This article introduces the classification of carbon emission sources and methods of carbon dioxide emission measurement in the cement production process. Carbon dioxide emission sources can be divided into direct emission sources and indirect emission sources, meanwhile methods of carbon dioxide emission measurement mainly include carbon dioxide emission calculation methods and carbon emission online monitoring measurement methods. This article provides an overview of the main technologies for carbon dioxide capture in the cement industry at home and abroad, with a focus on the current application status of oxygen enriched/full oxygen combustion technology in the cement industry. At present, the main technological paths for carbon dioxide utilization in the cement industry include concrete carbonation curing, waste slag mineralization utilization, and preparation of new carbon fixing materials. In the future, the cement industry needs to continue to make efforts in reducing carbon dioxide capture costs, optimizing carbon dioxide emission measurement methods, and efficiently utilizing carbon dioxide resources to further promote the achievement of carbon reduction goals in cement production.

This paper analyzes the sources and characteristics of carbon emissions and the main technical paths of carbon emission reduction in the cement industry. Therefore, breakthrough technologies such as novel and efficient carbon dioxide capture, utilization, and storage technologies, including oxy-fuel combustion, calcium cycling and post-combustion capture were introduced. The results indicate that the use of oxy-fuel combustion technology has lower overall costs and higher carbon reduction efficiency. Through tackling key core technologies and equipment for oxy-fuel combustion, developing the patented technology of “strong swirly pre-combustion furnace + CO₂-enriched combined calciner”. Based on CPFD simulation, combustion models in O₂/CO₂ and raw meal decomposition models under high CO₂ concentrations were established in depth to direct oxy-fuel coupled flameless combustion technology and thermal simulation pilot tests. The largest cement industrial-grade demonstration line with an annual capture capacity of 200 000 tons of CO₂ in the worldwide has been established. Practical applications show that using oxy-fuel combustion technology can enhance the CO₂ concentration in flue gas to over 80%. Finally, the concentration of CO₂ flue gas can be further increased to more than 99% by pressure swing adsorption and low temperature distillation.

Gradient combustion technology divides the furnace space of the calciner into functional partitions through multi-stage control of the air inlet, feeding, and coal injection, establishing a combustion atmosphere environment of "strong lean oxygen reduction zone - weak lean oxygen reduction zone - combustion zone", thereby achieving source emission reduction of NO_X. This article develops an online gradient combustion calciner and a supporting swirl dispersion burner, which can increase the residence time of the strong reduction zone to 2.5~3.0 seconds and improve the self denitrification effect. The application of this technology in the Tengzhou Dongguo production line shows that, the self denitrification efficiency can reach over 70%, the stable control of NOX at the outlet of the calciner is below 260mg/Nm³, and the NOX emission control of the chimney gas is 30~50mg/Nm³. the dosage of ammonia water used in the clinker production is less than 2.5kg/t, achieving low-cost and ultra-low emission of NO_X in cement kiln flue gas.

Hydrogen energy replacing fossil fuel to calcine cement clinker is an effective way to save energy and reduce carbon emission in cement industry. Based on the theoretical calculation of thermal engineering, the theoretical combustion temperature and gas volume of different fuels such as hydrogen were analyzed, and a small suspension calcining test platform was built to simulate the combustion state of the calciner, and the feasibility of hydrogen energy replacing fossil fuels in calcining cement clinker was analyzed and verified. Results show that hydrogen has no additional theoretical gas volume compared to conventional fuel. Hydrogen-enriched combustion of coal or alternative fuels has a positive effect on reducing CO and NO_X in suspension calcination, thus promoting the utilization of inferior fuel. As a low-carbon fuel, Hydrogen can further play a high activity to solve the technical bottleneck of incomplete combustion and high NO_X background emission of alternative fuel in the calciner. According to the experimental results, for reducing fossil fuel consumption and carbon emission, the industrialization technical route of 20% hydrogen energy coupled with 60% alternative fuel is proposed to calcine cement clinker. Before this route is applied to practical projects, more in-depth pilot study is needed.

The inlet duct and insulation design of AQC boiler in cement kiln waste heat power plant have a significant impact on boiler operation and heat utilization. To reduce heat loss and improve waste heat recovery efficiency, insulation measures need to be taken for the inlet duct. This article analyzes the heat transfer mechanism of the AQC boiler inlet duct, establishes a physical field model of the AQC boiler inlet duct, and conducts numerical simulation calculations using software of Fluent. The temperature field of the AQC boiler inlet duct with different inner insulation layer thickness and the linear relationship curve of the hot air temperature with the length of the duct are obtained. The numerical simulation results indicate that the most economical and reasonable design scheme for insulation layer thickness is when the thickness of the inner insulation layer of the inlet duct（?3 620mm×8mm）of the AQC boiler is 70mm, and the thickness of the wear-resistant casting material and outer insulation layer is 100mm.