Page 48 - Demo

PRODUCTION TECHNOLOGY48 PRODUCTION TECHNOLOGY AAC WORLDWIDE %u2022 2.2025accurately control the flow curve, resulting in cracking during steam curing, as well as incorrect pipeline design, the selection of the wrong valves, and unreasonable steam metering, ii) insulation defects related to unreasonable insulation design, which is associated with improper insulation thickness, improper selection of materials and inefficient construction layouts, iii) poor steam quality due to unstable pressure and temperature, excessive non-condensable gas content and steam impurities, and iv) wrong perceptions about steam application and energy conservation, which relates to a lack of emphasis on energy use, uninformed implementation of waste heat recovery systems, unreasonable energy management and dispatching systems, as well as a lack of systematic control of the front-to-end processes. Distribution of steam energy consumption in AAC plantsThe steam consumed by the moisture content in AAC accounts for 47%, while the steam consumed by the solids in AAC accounts for 25%. Several factors related to autoclaves also influence steam consumption, accounting for a total of 11%. In addition, steam consumed by the bottom plates of the autoclave curing cars accounts for 10% and steam consumed by the void fraction inside the autoclave accounts for 7%.Based on the steam consumption in the production process, one can understand the heat energy requirements of different areas of the production line and the proportion of steam consumption in each link of the autoclave curing process. This enables a more purposeful utilization of heat energy as well as an improvement of the production processes, the equipment, and the facilities overall. As a result, steam energy consumption can be reduced and losses in production quantity and quality caused by the irrational utilization of steam can be minimized.Approaches and practices of steam utilization and energy conservationAutomatic autoclaved curing systemOnly through an automatic autoclave system can the optimal autoclaved curing curve be achieved, which is demonstrated using the Ubinox Changxing factory as an example. This factory operates 9 autoclaves with dimensions of 2.72 %u00d7 38 meters in its first production line, where the exhaust gas has a pressure of around 2 bar and the unit consumption is approximately 110 kg/m%u00b3. For the second production line, there are 12 autoclaves with dimensions of 2.68 %u00d7 38 meters, with a gas exhaust pressure of around 1 bar and a unit consumption of approximately 100 kg/m%u00b3. In this factory, the fully automatic autoclaved curing system adopts flow control, precisely controlling the flow curve according to the set autoclaved curing formula. Compared with other domestic automatic autoclaves that use pressure control, the advantage of flow control is that it is an active control method, while the pressure control is passive. When the pressure signal is fed back to the regulating valve, the steam flow has already exceeded the amount required at this stage, thus leading to risks in the autoclaved curing process. The fully automatic autoclaved curing system can achieve fully automatic control of heating, which results in constant temperature and consistent steam transfer and cooling, Mesh drying >50%u25e6CCondensate heat exchangeCondensationSecondary steamboilercastingPulpingpower PlantAutoclave Static room >45%u25e6CEnergy consumption requirements in different areas of the production line.Autoclaving temperature regimes over time.ExothermtimePressure increase phasePressure decrease phaseConstant pressure phase Temperature of the AAC cake190 %u25e6C %u034c