Preparation of a new high-performance calcium-based desulfurizer using a steam jet mill

Study on the desulfurization performance of calcium-based desulfurizer and NaHCO3 desulfurizer

The commonly used calcium desulfurizers have low desulfurization efficiency. NaHCO₃ desulfurizers can meet the requirements of desulfurization efficiency, but the high price and the difficulty in handling desulfurization products make dry flue desulfurization technology quite difficult to realize the large-scale application. Preliminary research found a new calcium desulfurizer, to understand its performance, comparing investigation into the desulfurization performance of different calcium desulfurizer and NaHCO₃ desulfurizer. The results showed that with the high-performance calcium desulfurizer, conventional NaHCO₃ desulfurizer, and ultrafine NaHCO₃ desulfurizer, the operating time with 100% desulfurization efficiency is 25,200, 21,600, and 6000 s, when the flue temperature of 373.15-573.15 K, the "break-through" temperature is 533.15, 473.15, and 373.15 K, expand the use range of desulfurizer flue gas temperature. Regarding the desulfurizer per unit mass, the production costs of ultrafine NaHCO₃ desulfurizer are 5.36 times higher than calcium desulfurizer. Compared with NaHCO₃ desulfurizer, high-performance calcium desulfurizer is characterized by several advantages, including high desulfurization efficiency, wider applicable temperatures, and low preparation cost, allowing for significant development potential in flue gas desulfurization.

An efficient calcium-based sorbent for flue gas dry-desulfurization: promotion roles of nitrogen oxide and oxygen

The development of sorbents for flue gas desulfurization in a dry mode is essential to control emission of sulfur dioxide. Based on the novel concept of "treating waste with waste", a low-cost and highly activated calcium-based sorbent (ACS) was prepared using coal fly ash, CaO and waste gypsum as the raw materials via the one-step incipient wetness impregnation method. Based on characterization using scanning electron microscopy and nitrogen adsorption-desorption, the ACS possessed a fibrous and netted structure with high porosity, which improved SO₂ adsorption greatly. The SO₂ adsorption capacity of ACS with coal fly ash/CaO/CaSO₄ = 1/2/1 was high, up to 44.26 mg g^-1, with 100% removal efficiency at 150 °C. In the absence of O₂, SO₂ was rapidly adsorbed on the sorbent to form CaSO₃ according to in situ DRIFTS analysis, while when O₂ was present in the flue gas, SO₂/SO₃ ^2- tended to be oxidized into SO₄ ^2- species. Moreover, the presence of NO can further enhance the SO₂ adsorption capacity of the ACS due to the formation of adsorbed NO₂ or nitrate species with strong oxidizing properties. Therefore, the ACS can be considered as a sustainable sorbent with the advantage of employing fly ash for the removal of sulfur dioxide.

The boosting of microwave roasting technology on the desulfurization of phosphate rock

A green and-easy to operate method, the microwave technology, was developed to promote the desulfurization process of phosphate rock, systematically investigates the strengthening effect of microwave, and uses XRD, BET, SEM, XRF, ICP, and EDS to characterize the reactants. The results show that the main reason for the desulfurization efficiency is improved by microwave heating under microwave conditions, different thermal stress phosphate rock materials lead to the destruction of each microstructure, and a specific surface area increased 40.25% phosphate rock. In addition, after microwave irradiation, the pore size of the phosphate rock at 2-5 nm is significantly increased, and the number of mesopores is significantly increased, thereby increasing the desulfurization efficiency of the phosphate rock. By investigating the effects of temperature, oxygen content, flow rate, and solid-liquid ratio on desulfurization efficiency, the paper concludes that the optimal conditions for desulfurization of phosphate rock after microwave irradiation are C(SO₂) is 2500 mg·m^-3, temperature is 40 °C, φ(O₂) is 5%, solid-liquid ratio is 3.5 g:200 ml, and flue gas flow is 500 ml·min^-1.