Cement Suspension Preheater Calcining Technology with High Solid-Gas Ratio

A High solid-gas ratio preheater system provides for two parallel twin series of air (laden with the solid materials) streams, making solid-gas ratio per unit doubled or more for each preheater, so that the heat consumption of clinker production tends to be close to the theoretical thermal consumption. The Preheater system is set as a combined multi-level series of five preheater cyclones in the framework of 2-2-2-2-1, in which gas from each of the five cyclones flows evenly through each stage of parallel dual series preheater, all the powder alternately step-wise fed into preheater cyclones from one series to another series, and solid-gas ratio of the preheater cyclone increased to about 2.0, so that it significantly improves the heat exchange efficiency of the total preheater system and reduces the exhaust gas temperature at the preheater exit.

An “External Circulation Calciner” system of high solid-gas ratio adopts a "bypass outside" approach, in which a certain amount of solid materials exit from the calciner and return to the calcining furnace, so that large particles of insufficient calcining rate continue to calcine repeatedly through the high furnace temperature and the more intense heat release area by the second, third or even fourth times, so that it can increase the calcination rate of material exiting from the Calciner, reduce the thermal load of the rotary kiln, greatly improve the kiln production of per unit volume, simultaneously strengthening the thermal stability of precalciner, and finally reducing harmful gas emissions (NDRC, 2011. p. 35).

Chinese Flag According to NDRC, the main technical indicators of this technology include the following: 

  • exhaust gas temperature from Kiln inlet is less than 260 ℃;
  • heat energy consumption for clinker making is below 2.85 GJ/t-clinker (680Mcal/t-clinker);
  • power consumption is less than 56kHh/t-clinker;
  • operating rate of kiln system is greater than 90%;
  • NOx and SO2 contents in exhaust gas are less than 200ppm and 50ppm, respectively (NDRC, 2011. p.36)

In China, this technology is expected to reach a market share of 5% by 2015. This will require an investment of 5.5 billion RMB for new developments and plant upgrades, and has the potential to save 26.38 PJ of energy annually (NDRC, 2011. p.37)

Development Status Products
Commercial
clinker

Cement Suspension Preheater Calcining Technology with High Solid-Gas Ratio Costs & Benefits

Parent Process: Clinker Making
Energy Savings Potential

Chinese Flag Heat energy consumption for clinker making can be reduced below 2.85 GJ/t-clinker. Savings of 14.3 kg of standard coal per ton of clinker can be realized (NDRC, 2011. p.37)

Chinese Flag In a Chinese plant with 2500 tpd capacity, the installation of this technology reduced annual energy consumption by 571.5 TJ (19 500 tce) (NDRC, 2011. p.37)

Chinese Flag In a Chinese plant with 3000 tpd capacity, the installation of this technology reduced annual energy consumption by 633 TJ (21 600 tce) (NDRC, 2011. p.37)

CO2 Emission Reduction Potential

N/A

Costs

Chinese Flag Installation of this technology in a Chinese plant with 2500 tpd capacity required an investment of 35 million RMB, and took one year to complete. The economic benefits of saved energy was about 34.5 million RMB, resulting in a payback time of around 1 year (NDRC, 2011. p.37)

Chinese Flag Installation of this technology in a Chinese plant with 3000 tpd capacity required an investment of 35 million RMB, and took one year to complete. The economic benefits of saved energy was about 37.2 million RMB, resulting in a payback time of 10 months (NDRC, 2011. p.37)

Cement Suspension Preheater Calcining Technology with High Solid-Gas Ratio Publications

National Key Energy-Saving Technologies Promotion Catalogue (Fourth batch)

Published by the National Development and Reform Commission of China, this directory provides information on 50 energy-efficient technologies applicable to 9 industries such as coal, electricity, iron and steel, nonferrous metals, petroleum and petrochemicals, chemicals, building materials, machinery, textile and others.

Page Number: 

35-37