As a pioneer within energy-enhancing technologies aimed at enhancing the energy efficiency of cement plant operations, FLSmidth first released the SF™ cooler in 1997.
With this cooler, which separated the conveying and cooling mechanisms, the objective was consistency in fuel consumption. And in the 14 years since its release, with almost 250 installations in operations ranging from 540 tpd to 13,000 tpd clinker production, the SF cooler has achieved impressive results.
Over this time, however, a number of important factors in cement production have changed, such as raw materials, fuels, market demand for different quality clinkers and alternative fuel usage. Despite these changes, the cooler plays a key role in producing high quality clinker.
Fuel consumption consistency
In 2010, the FLSmidth® Cross-Bar® cooler was launched, largely in response to common operational challenges, such as snowmen, red rivers and inconsistent clinker PSD (Particle Size Distribution). In less than five years, it has been installed in more than 70 operations ranging from 1,100 tpd to 12,500 tpd clinker production.
This cooler has helped achieve even greater consistency in specific fuel consumption for clinker production across the complete pyro system. By having separate conveying and cooling mechanism and by providing uniform cooing air by mechanical flow regulators (MFRs), the Cross-Bar cooler has showcased the consistency in fuel consumption for the more than 18 years since the SF cooler was launched in 1997.
A one percent loss in cooler efficiency will increase fuel consumption by 5 kcal/kg clinker. This, in turn, has a direct impact on the preheater fan power consumption, coal mill run hours, coal handling and conveying system. Savings from the constantly higher recuperation from Cross- Bar coolers outweighs the marginal savings in specific power consumption of the older generation beam technology coolers.
Upgrade at Awarpur Cement Works
Ultratech Cement Limited, Awarpur Cement Works is one of India’s oldest plants and is located in the Maharashtra State of India. It has two lines in operation with a combined operating capacity of 3.3 MTPA of clinker production. The Line 1 pyro system operated with a four-stage SLC tower and CFG grate cooler operating at 4000 tpd clinker production.
Ultratech chose FLSmidth as its one source partner to upgrade its Line 1 pyro system in two phases. FLSmidth was responsible for the complete civil engineering, mechanical engineering, E&I engineering and hooking up the newly installed equipment with the existing PLC for the complete upgrade project.
Table 1: FLSmidth® Cross-Bar® cooler parameters recorded during baseline & performance guarantee trails
The first phase involved replacing the existing grate cooler with the new FLSmidth Cross-Bar cooler. Supported by Ultratech Cement, FLSmidth completed the cooler replacement and fired up the plant in November 2014. The performance guarantee trials were run almost a year later in October 2015. This allowed sufficient time to demonstrate the consistency in cooler performance and cooler losses.
Ultratech Cement incorporated its existing waste heat recovery (WHR) system into the cooler and in the preheater system. Table 1 portrays the before and after conditions of the hot air taken for power generation in the prevailing WHR system.
Maximum heat efficiency
In the FLSmidth Cross-Bar cooler, the quality of heat is maintained in such a way that the recuperation and the WHR system receives the maximum heat available from the red-hot clinker. This is because less air is pumped than in the older generation beam technology coolers, and it is pumped from underneath the compartment efficiently by means of MFRs. This, in turn, maintains the required airflow to the upper clinker bed and ensures uniform cooling and better heat removal from the hot clinker. As the heat available in the hot clinker is not diluted by pumping more air, the above parameters are achieved without recirculation of hot air from cooler vent. This does not compromise the clinker temperature.
Table 2: Mid air to waste heat recovery, before & after installation of FLSmidth® Cross-Bar® cooler