Recently, Zhenghe Group made use of the overhaul break to finish renovation of its DCC top circulation and gas separation depropanizer. The renovation will bring down steam consumption for production, making full use of energy and saving costs by nearly 10 million yuan ($1.64 million).
Technical personnel found that there were big temperature differences when directly using DCC top circulating oil to heat mixed materials. Using 1.0MPa steam to heat the depropanizer was also inefficient.
To start renovation work, technicians added a reboiler at the bottom of the depropanizer and sent the circulating oil (152 C) from the top of the DCC fractionation tower to the reboiler as a heating source in place of steam. They then returned the oil (132 C) to the DCC unit. The oil then exchanged heat with raw materials and finally went back to the fractionation tower at 105 C. The renovation can save 5.4 tons of 1.0MPa superheated steam per hour and bring down energy consumption by 4.09kgEO/t. At the same time, it also optimized the DCC raw material feeding and heat exchanging network.
The smooth implementation of the project marks a step forward for Zhenghe in energy optimization. The company has effectively reduced comprehensive energy consumption and increased profits by more than 800 million yuan per year.