Diesel Flue Gas Treatment by Intense, Pulsed Relativistic Electron Beam, страница 2

Results and Discussion

Characteristics of current and kinetic energy of IREB injected into flue gas treatment chamber

Figure 3 shows the typical time evolution of acceleration voltage of IREB (V_a) and IREB current (I_b and I_c), where I_b and I_c are measured by a Faraday cup placed at the inlet of the drift and the gas chamber, respectively. It is found that the peak current of the IREB decreases form I_b ~2.6 kA to I_c ~0.12 kA due to the kinetic-energy loss and scattering of the electrons within the window, bulkhead and air in the drift chamber. It does not matter in practical application, because part of current loss is effective for the flue gas treatment if the drift chamber is also filled up with the flue gas. The injected IREB energy into the gas chamber is estimated to be e ~ 2 × 10^–6 kWh from the time integral of the product of V_a and I_c.

Figure 4 shows the kinetic energy distribution of the IREB injected into the drift and gas chamber. The kinetic energy is observed by measuring the IREB current passed though the various sets of thin metallic foil with energy loss. The foil is placed at the inlet of the drift and the gas chamber. It is found that the maximum kinetic energies of the IREB injected into the drift and the gas chamber are estimated to be ~0.87 and ~0.23 MeV, respectively. In the gas chamber, however, more than half number of the electron has kinetic energy below ~ 0.092 MeV.

Diesel flue gas treatment by IREB irradiation

Figure 5 shows the concentrations of NO, NO₂, SO₂, CO, and CO₂ as a function of number of the IREB irradiation in cases without and with the 2.5-kW load of the diesel generator. It is found that the concentrations of NO_x (sum of NO and NO₂) is successfully reduced by irradiating the IREB regardless of the load of the diesel generator. We found that ~93 and ~85 % of NO_x are treated by firing 10 shots of the IREB irradiation in cases with and without the load of the diesel generator, respectively. Although concentration of SO₂ decreases from 14 to 11 ppm by firing 10 shots of IREB irradiation in case without the load, the SO₂ is not treated by the IREB irradiation in case with the load. The energy efficiency of NO_x removal (q / e, where q is the amount of NO_x removal in each IREB irradiation) is estimated to be 256 g/kWh which is somewhat higher than that obtained by discharge treatments [10,  11].

Figure 3. a — time evolution of IREB acceleration voltage V_a; b — IREB current at window of drift chamber I_b; с — IREB current at bulkhead of gas chamber I_c

Figure 4. a — Kinetic energy of IREB in: drift chamber; b — gas chamber

Conclusion

The diesel flue gas in the chamber 1.6-m isolated from the IREB source has been successfully treated by the IREB irradiation. With the initial NO_x concentration of 75 ppm, ~93 % of NO_x is removed by firing 10 shots of the IREB. The energy efficiency of NO_x removal has been found to be ~ 256 g/kWh.

Acknowledgments

This work was supported in part by the Ministry of Education, Culture, Sports, Science, and Technology in Japan under a Grant-in-Aid for the Scientific Research.

Figure 5. Concentrations of NO, NO₂, SO₂, CO and CO₂ as a function of number of IREB shots in cases: a — without 2.5-kW load; b — with 2.5-kW load of diesel generator. ○: NO, ▲: NO₂, ×: SO₂, □: CO, and ●: CO₂

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