May-2025

Solutions for heat tracing in the decarbonisation of cement

Heat tracing solutions are instrumental in addressing several challenges in the cement industry, playing a pivotal role in reducing its carbon footprint.

Koen Verleyen
Chemelex

Article Summary

The cement industry is at a critical juncture in its journey towards net-zero emissions. As one of the most energy-intensive and carbon-emitting industries (~8% of global CO₂ emissions (Facts on climate, 2019), cement manufacturing faces numerous technical challenges in reducing its carbon footprint (Lehne & Preston, 2020). These challenges are primarily related to the inherent nature of cement production, which involves high-temperature processes and significant CO₂ emissions.

Heat tracing solutions are emerging as a key technology to enhance process efficiency, reduce energy consumption, and facilitate the integration of low-carbon technologies.

Technical challenges in cement industries:
υ High-temperature process requirements
Cement production involves several high-temperature steps, particularly in the kiln, where raw materials are heated to 1,450°C (2,642°F) to produce clinker. This process is not only energy-intensive but also results in significant CO₂ emissions due to the decomposition of limestone (calcination) and the combustion of fossil fuels. The challenge lies in finding ways to reduce energy consumption and emissions without compromising the high temperatures required for clinker production.

ϖ Energy efficiency and heat loss
The high-temperature processes generate significant heat, much of which is lost to the environment due to poor insulation and process inefficiencies. Improving energy efficiency is essential to reducing the carbon footprint of cement production, but this requires innovative solutions to capture and utilise the excess heat generated during the process.

ω Integration of alternative fuels
The cement industry is exploring the use of alternative fuels, such as biomass, waste-derived fuels, and hydrogen, to replace traditional fossil fuels. However, these alternative fuels often have different combustion characteristics, affecting the stability and efficiency of the kiln operation. Biomass and waste-derived fuels have lower calorific values and higher moisture content, which can lead to incomplete combustion and higher energy consumption. Ensuring consistent and efficient combustion of alternative fuels is a significant technical challenge.

ξ Carbon capture utilisation and storage
Carbon capture and storage (CCS) or carbon capture, utilisation and storage (CCUS) technologies are critical to reducing the industry’s carbon footprint. However, capturing CO₂ from the high-temperature flue gases of cement kilns presents technical challenges.

The flue gases should be cooled before CO₂ can be captured, which involves further energy input.

Additionally, for CCS to be effective, precise thermal management is required. The process of capturing CO₂, whether through post-combustion, oxy-fuel combustion, or pre-combustion technologies, involves several temperature-sensitive steps. Maintaining optimal temperatures is crucial for the efficiency of solvents, membranes, or other capture mediums. Any deviation from the required temperature range reduces the CCS efficiency and increases its energy consumption.
 
Role of heat tracing
Heat tracing involves the application of electrical heating cables to pipes, vessels, and other equipment to maintain or elevate temperatures to a desired level. In the context of the cement industry, heat tracing solutions are instrumental in addressing several challenges outlined above.

υEnhancing energy efficiency
Heat tracing systems can significantly improve the energy efficiency of cement plants by minimising heat loss in critical areas. For instance, in the clinker production process, heat tracing can be applied to maintain the temperature of raw materials and prevent heat loss during transportation through preheaters, kilns, and coolers. This ensures that less energy is required to maintain the high temperatures necessary for calcination, thereby reducing overall energy consumption and CO₂ emissions.

Heat tracing can also be used to optimise the operation of heat exchangers and waste heat recovery systems, which are integral to improving energy efficiency in cement plants. By maintaining optimal temperatures in these systems, heat tracing helps maximise the recovery of waste heat, which can then be reused in the production process, further reducing the need for external energy inputs.

ϖ Supporting the use of alternative fuels
The integration of alternative fuels into cement production processes requires careful thermal management to ensure consistent and efficient combustion. Heat tracing solutions can be employed to preheat alternative fuels with high moisture content, such as biomass, before they enter the kiln. This preheating reduces the moisture content of the fuel, improving its combustion characteristics and ensuring a stable and efficient burning process. As a result, the use of alternative fuels becomes more viable, helping to reduce the industry’s reliance on fossil fuels and lower its carbon footprint.

ω Optimising CCUS processes
Heat tracing plays a crucial role in the optimisation of carbon capture systems. In post-combustion carbon capture, for example, flue gases must be cooled to a specific temperature range before CO₂ can be efficiently captured. Heat tracing systems can be used to precisely control the cooling process, ensuring that flue gases reach the required temperature for optimal CO₂ absorption by solvents or membranes.

Furthermore, heat tracing is essential in maintaining the temperature and pressure conditions required for the transportation and storage of captured CO₂. By preventing temperature fluctuations in pipelines and storage vessels, heat tracing helps maintain the integrity of the carbon capture process, ensuring that CO₂ is safely and efficiently transported to storage sites or utilisation facilities.

ξ Enhancing process control and stability
In cement production, process stability is critical to maintaining product quality and reducing energy consumption. Heat tracing solutions provide precise temperature control, which enhances the stability of key processes, such as kiln operation and fuel combustion. By maintaining consistent temperatures, heat tracing minimises the risk of process disruptions, which can lead to energy inefficiencies and increased emissions.