Research On Cyclic Energy Storage Performance Of Calcium-based Sorbent

The energy consumption structure with fossil energy as the main body has the risk of energy shortage,and the development and utilization of solar energy can effectively reduce dependence on fossil energy,but reasonable energy storage technology must be adopted to ensure the continuous supply of energy.Thermochemical energy storage technology,which has almost no energy loss,high energy storage density and low raw material price,has attracted widespread attention.However,the energy storage activity of calcium-based sorbent will decrease with the increase of the number of cycles.Therefore,it is necessary to take effective measures to solve the problem of sorbent performance attenuation in order to maintain the efficiency of calcium cyclic energy storage.Y₂O₃ inert carrier was used to modify the sorbent by doping.As a physical barrier,Y₂O₃ prevents CaO particles from agglomeration and improves the sintering resistance of the sorbent.The sorbent shows good energy storage density and excellent cyclic stability.35 wt%is considered as the optimal addition amount of Y₂O₃,and the corresponding sample can achieve energy storage density of more than 2000 k J/kg,and can maintain around 1400 k J/kg under harsh calcination conditions.The modified sorbent was granulated into spherical shape by extrusion-spheronization method.The energy storage performance of the formed sorbent decreased slightly,but it had good wear resistance,and only 4.28%of the initial mass was lost after 7000 rotations of friability test.The sorbent is reactivated by absorbing water in the environment.CaO absorbs water to generate Ca（OH）₂ and[Ca（OH）₂·2H₂O],which will leave pores in the sorbent after calcination,thus restoring the energy storage activity of the deactivated sorbent.After reactivation,the cumulative energy storage capacity of sorbent in 10 cycles was also increased by 58%,and it is also effective for molded sorbents.It was found that the secondary activation of the sorbent could stimulate the energy storage activity of the sorbent again,and when the sorbent was activated every 5 cycles,a cumulative energy storage capacity of 28925 k J/kg could be achieved within 20 cycles,while the unactivated sorbent was only half that level.The presence of SO₂ in the carbonation stage will accelerate the decay of the sorbent’s energy storage performance because of the irreversible acidification reaction.