| The hydrogen manufacturing unit of Daqing Petrochemical Company uses hydrocarbon vapor method. In the original design, the virable gas of medium temperature is used to heat demineralized-water. This causes energy waste, leads to the much higher pressure of air cooling load and water cooling load, and even affects the stability of the pressure swing adsorption system(PSA) in summer. Based on the analysis of the original technology process, the technical reform project of waste heat recovery is established. A heat recovery device can be installed between the second liquid seperate pot of variable gas and air cooler. The exccess heat of viriable gas can be transfered with demineralized water and raise the temperature of the demineralized water. The cost of the steam in deaerator system can be reduced as the amount of dissolved oxygen in water varies inversely to the water temperature. The air cooling load can be reduced with the lower temperature of variable gas. Having adopted this technique, the demineralized water in deaerator system can be heated to at least 77 ℃, and the exhaust of 1.0 MPG steam in dearator and electricity in air cooling system of variable gas can be reduced. The energy-saving can be finally achieved. Meanwhile, the requirment of oxygen removal can be meeted under larger load operation, and the stability of the devices can be maintained.Based on the caculation and analysis of investment estimation, financing plan, Cost estimation and the project profitability, it can be concluded that this energy-saving technology design has good economic benefit. The financial internal rate of return can be 15.855, higher than the industry benchmark yield. The energy consumption reduction should be 976.12 MJ/t industrial hydrogen(23.31 kg oe/t industrial hydrogen) after the installation of this technique.To sum up, the energy consumption and the production cost can be reducd with this energy-saving technology design, and the utilization of heat is more reasonable. |
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