Abstract:

Currently, the steam pipelines in cigarette factories are characterized by numerous points, extensive lengths, and broad coverage. The thermal conversion factor of these pipelines is high, and their steam energy consumption accounts for a large proportion of the total energy consumption. Therefore, investigating the performance of the insulation layer of steam pipes is of considerable importance for improving steam utilization efficiency and reducing heat loss in the steam pipe network. In this study, the thermal conductivities of insulation layers made of four insulation materials were measured using the steady-state method at different temperatures to elucidate the relationship between the thermal conductivity of an insulation material and the steam temperature, thereby identifying the efficient insulation materials suitable for application scenarios. The appropriate insulation layer thickness was determined using the maximum allowable heat loss method and economic thickness method. Moreover, the thermal conductivities of insulation layers with different service lives were measured. Results indicate that the thermal conductivity increased linearly with the increasing service life. Factors causing the deterioration of insulation layer performance were incorporated into the model to study the relationship between the operating cost of an insulation layer and its outer diameter and service life. For insulation layers with different designed service lives, their optimal outer diameters and operating costs were calculated using the economic thickness method. Results show that considering material aging factors in the design of insulation layer thickness can reduce cumulative costs by 10.7% within the designed service life. However, when the service life expires, the operating cost of a design that considered the aging issue is higher than that of a design that did not consider the aging issue owing to increased heat loss as a result of aging of the insulation layer. The insulation layer can be designed to reduce steam heat loss and improve steam utilization efficiency as well as provide theoretical guidance for the green, low-carbon, and high-quality development of cigarette factories.

Key words: thermal insulation, thermal conductivity, maximum allowable heat loss method, economic thickness method, performance deterioration