The necessity of electric heating tape in the coal water slurry pipeline

　　In the field of coal chemical industry and thermal power generation, coal-water slurry is an important fuel substitute for oil, and the stability of its pipeline delivery system directly affects the production efficiency and energy security. Coal water slurry is a non-Newtonian fluid mixed by 60%-70% of coal powder and 30%-40% of water and additives, and its rheological properties are extremely sensitive to temperature changes. The application of electric accompanied by the tropical belt system, through the accurate temperature control to maintain the best flow state of coal water slurry, become an indispensable technical means to ensure the safe operation of the pipeline.

　　The rheological characteristics of coal water slurry determines the necessity of temperature control. When the temperature is lower than the critical value, the viscosity of coal-water slurry rises sharply, the fluidity deteriorates significantly, and the pipeline resistance increases exponentially. Experimental data show that for every 5 ℃ reduction in coal water slurry temperature, the pumping pressure needs to be increased by 15-20%, which not only significantly increases energy consumption, but also may lead to pipeline clogging accidents. In the measured case of a coal chemical industry base in the north, the electric heating tape maintains the temperature of the pipeline in the optimal range (usually 45-55℃), so that the coal water slurry always maintains the uniform suspension state, and the viscosity stabilises in the ideal range of 800-1200mPa-s, ensuring the efficient and smooth operation of the conveying system.

　　Anti-freezing protection is a survival requirement for coal water slurry pipelines in cold regions. Water in coal water slurry freezes in low temperature environment, which will lead to agglomeration and settlement of coal particles, forming irreversible solid-phase separation. A northeastern power plant has been due to extreme cold wave attack, not accompanied by heat pipeline inside the coal water slurry freezing, resulting in 300 metres of pipeline scrapped, the direct economic loss of more than a million yuan. The electric accompanies the tropical belt system to be equipped with the temperature sensing and the automatic control function, can in the environment temperature suddenly drops when the start, prevents the medium temperature to fall below the safety threshold value. The unique advantage of self-limiting temperature electric accompanying heat belt is that its power increases automatically with the decrease of temperature, which matches the non-linear characteristic of anti-freezing demand, not only ensures the safety but also avoids the waste of energy. This self-adaptive ability makes the system still work reliably in the extreme cold environment of minus 30℃, which provides a key guarantee for coal water slurry application in high latitude area.

　　The maintenance of coal-water slurry quality is also critical with electric heat tracing systems. Temperature fluctuation will destroy the effect of additives and affect the surface wettability and dispersion stability of coal particles. Laboratory comparison shows that when the temperature fluctuation exceeds ±5℃, the static stability time of coal water slurry is shortened by more than 40%. The pipeline system with electric heat tracing can control the temperature fluctuation within ±2℃, effectively maintaining the chemical activity of additives. Data from a demonstration project confirms that stabilised heat tracing reduces the settling rate of coal-water slurry from 1.2%/h to 0.3%/h, extends the storage time by three times, and significantly reduces mixing energy consumption and quality deterioration losses. This kind of fine regulation of fluid characteristics is difficult to achieve with other heating methods.

　　From the system reliability point of view, electric accompanying heat has obvious advantages compared with steam accompanying heat. The steam accompanies the heat to exist the temperature control lag, the heat efficiency is low (usually only 35%-45%), the condensate treatment and so on the problem. And the electric accompanying heat system thermal efficiency can reach 90% above, response speed is 5-8 times faster, especially suitable for coal water slurry conveying this kind of need to quickly adjust the occasion. Electric accompanied by the modular design of the tropical also improves the reliability of the system, a single point of failure does not affect the overall operation, maintenance downtime reduced by more than 70%.

　　The fusion of intelligent control technology further amplifies the value of electric trace heat system. Modern coal water slurry pipeline electric accompanying heat system is equipped with distributed temperature sensing network, real-time monitoring of temperature distribution along the course, predicting changes in flow resistance through AI algorithms, and adjusting heating strategy in advance. An intelligent demonstration project has achieved in-depth integration with the DCS system, automatically optimising temperature control parameters according to coal quality changes and flow fluctuations, so as to reduce transport energy consumption by another 12%. The data traceability function also provides a valuable basis for process improvement.

　　With the advancement of the goal of ‘double carbon’, the clean application of coal water slurry technology will continue to expand, and the requirements for the conveying system will also continue to improve. Electricity accompanies the heat technology by virtue of its accurate temperature control, high efficiency and energy saving, intelligent and controllable advantages, will certainly play a greater role in the field of coal water slurry pipeline. From basic antifreeze to process optimisation, from energy consumption reduction to safety enhancement, electric accompanying heat system is through the precise control of temperature as the key parameter, to provide solid technical support for the large-scale industrial application of coal water slurry. In the background of energy transformation, this seemingly simple temperature maintenance technology, in fact, has become an important cornerstone to ensure the clean and efficient use of coal.