Off-design Performance Of Solar Hybrid Heating Power Plant

Fossil fuels are becoming scarce, the energy shortage problem has attracted more and more attentions. The research of new energy has become a hot spot of the world. As the most potential of renewable energy in new energy, the solar energy has shown more and more important position. Small coal heating power plant in our country has been facing elimination because of the low efficiency and severe pollution. It will not only waste the resources, at the same time can also cause the local heating capacity is insufficient. This paper aimed at the small unit coal-fired power station. Research on the complementary system of middle and low temperature solar energy and small unit heating power plant. The thermal performance of solar and coal complementary system under variable radiation or variable conditions is discussed. The main research contents and results were as follows:Firstly, on the basis of a 12 MW heating power station build a thermal system model, the actual operation data is referenced in power stations. Verify the design model under different loads(were 80%,65%,50%). On the basis of this, solar energy and power plant thermal system coupling model is established. On the basis of integrated way which takes advantage of solar energy heat instead of the steam turbine extraction, a new way of complementary integration is proposed. That is, the solar collector field and the heating of a parallel network of complementary way. The two integration modes were compared under the variable condition in order to observe thermal performance of the system.Secondly, based on the first law of thermodynamics, analysis of the influence of solar radiation intensity on the two complementary systems. To evaluate the power generation and heating in the system using the total thermal efficiency and coal saving rate. Results show that the solar thermal field and heat supply network parallel complementary modalities in the total thermal efficiency and coal saving rate is better than that of the solar alternative high-pressure pumping steam complementary way. The total thermal efficiency gap can reach 12%. The effect of heat conduction oil temperature on the two systems in the solar heat collection system is analyzed. Unit load in 80% and 65%, respectively, in the heat conducting oil temperature reached 355℃ and 350℃, the complementary system in parallel with the solar and heating network total thermal efficiency is higher.Finally, based on the theory of energy analysis, the two complementary systems are evaluated using the exergy efficiency growth rate and growth rate of thermal efficiency. Variation on the complementary system in thermodynamic performance is intuitive show. Results show that the solar thermal field and heat supply network directly parallel the complementary system is better than the complementary way of solar thermal field instead of the high pressure heater extraction steam. Equipment exergy loss coefficient of two kinds system was analyzed. Major equipment exergy loss distribution in the system was compared. Reveal the energy distribution in the system. Two complementary systems of energy utilization are analyzed. The results show that the complementary system reduces the irreversible loss in the system, and effectively improves the energy efficiency of the system.