Study On Chemical-Power Polygeneration And Integration Mechanism

The polygeneration is promoted to meet requirements such as enhancing efficiency and environment friendliness of power generation system and chemical production. By integration, the polygeneration system realizes the effective and clean utilization of fossil energy. Polygeneration is more and more important in the sustainable development. Supported by the National Key Projects Fund and National Science Foundation key project, the aim of this research is to investigate the key problem of integration in polygeneration, to study system integration mechanism, to explore performance variation regularity with different material and different product, and to propose new polygeneration system.Based on chemical and physical energy cascade utilization theory, the energy utilization equations of polygeneration are concluded, and the mechanism of system integration is studied. The units of system are full analysed and studied, the mathematics models of units are established, and key parameters are withdrawed. The analysis of function island level is added to fill the gap between process level analysis and system level analysis. By following the step of process, function island and system, the influence of key parameters is revealed. A serial of system characteristic equations with well applicability is proposed for the first time. Those equations described the energy conversion and utilization. Taken coal based DME polygeneration for example, the polygeneration system is reviewed with equations. The regularity curves of units exergy loss, function island exergy loss and system performance, which are varied with key recycling ratio, are investigated. It is founded that the integration and optimisation are followed the cascade utilizaiton theory of chemical energy and physical energy.Two typical coal-based polygeneration systems have been studied, and the impact of chemical energy and physical energy cascade utilization to system integration is revealed. The Primary Energy Saving Ratio (PESR) of one through two step DME-power polygeneration is 7.2%, and the PESR of one through one step DME-power polygeneration is 17.6%. By analysis it is founded that both physical energy and chemical energy cascade utilization are enhanced, and the polygeneration performance is improved as result. The essential reason for the higher PESR in one step DME polygeneration is the more full utilization of chemical energy in fuel.Natural gas based DME-power polygeneration and methanol-power polygeneration are proposed. The integration mechanism of composition conversion and energy utilization in hydrogen riched polygeneration is invested. The integration method, which could effective improved system performance with low carbon to hydrogen ratio, is exploited. The PESR of once through methanol polygeneration is 3.3%, the PESR of partial recycling methanol polygeneration is 10.9%, the PESR of DME polygeneration is 10.2%, and the the PESR of partial recycling DME polygeneration is 13.4%. The comparison shown that the natural gas based chemical individual generation is partial realized cascade utilization of chemical energy and physical energy, and the potential of it is smaller than coal based chemical individual generation. There is obvious difference between polygeneration systems with different input material, but the system integration and optimazation are follows the cascade utilization theory of chemical energy andphysical energy.