International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry最新文献

The basic features of the mechanism of the solid state radiolysis of the title polyethers have been elucidated with an ESR study using the matrix isolation and spin-trapping techniques. The species identified at 77 K are α-alkoxy radicals arising from hydrogen abstractions probably involving the primary ether cation-radicals; chain scission radicals are formed on warming as a consequence of the thermal decomposition of the α-alkoxy radical precursors. The formation of acyl and α-keto radicals, which is observed on warming near room temperature, is identified with cage hydrogen abstraction reactions taking place between the products of the β-scission of the α-alkoxy radicals. Direct information on the stability and ESR properties of the polymeric ether cation-radicals, which are thought to be important intermediates in the radiolysis mechanism, have been obtained by irradiation in the CFCl₃ matrix.

Absolute calorimetric dosimetry and relative dose mapping methods are described for a 400 keV electron accelerator used for polymer curing and crosslinking experiments. These methods of dosimetry are also useful at accelerators used in gas cleaning processes.

Double stage gas irradiation (2 electron accelerators, $\text{50 kW}\text{700 keV}$ each) is the main technological principle employed in the Polish pilot plant (20,000 Nm³/h) constructed at EPS Kawȩczyn (low/medium sulphur coal). The pilot plant design is described in the paper.

Energy efficiency of the simultaneous removal of NO_x and SO₂ from flue gas by the EBDS process may be improved by applying multiple irradiation with intermediate product scrubbing. The product, which is a mixture of ammonium sulphate and nitrate, can be filtered using bag filters and gravel bed filters yielding a by-product which is suitable for agricultural purposes. Due to the recent development of high power accelerators the costs of the EBDS process are now competitive when compared to conventional flue gas treatment methods.

The computer monitoring system applied in the electric and thermal power plant in Kawȩczyn is described. Requirements for a computer monitoring and control system in an industrial flue gas cleaning plant is also presented.

The concise review of dosimetric methods suitable for gas phase is presented. The spatial dose distribution from low energy high power electron accelerators, the ELV-3A type, inside the process vessel of industrial flue gases was measured. Complementary measurements using small power and the same energy Van de Graaff were also performed. The agreement between measured and theoretically predicted results is satisfactory.

The methods and system used for determination of the gas composition at the inlet and outlet of the pilot installation are presented. The concentrations of SO₂, NO, NO_x(NO + NO₂) and O₂ are measured continuously by two independent emission monitoring systems (one at the inlet and another at the outlet) and occasionally by the grab sample system, i.e. by manual analytical methods. The remaining components of the gas are determined only by the grab sample system.

The electron-beam process is one of the most effective methods of removing SO₂ and NO_x from industrial flue gases. This flue gas treatment consists of adding a small amount of ammonia to the flue gas and irradiating the gas by means of an electron beam, thereby causing reactions which convert the SO₂ and NO_x to ammonium sulfate and ammonium sulfate-nitrate. These salts may the be collected from the flue gas by means of such conventional collectors as an electrostatic precipitator or baghouse. This process has numerous advantages over currently-used conventional processes as follows: (1) the process simultaneously removes SO₂ and NO_x from flue gas at high efficiency levels; (2) it is a dry process which is easily controlled and has excellent load-following capability; (3) stack-gas reheat is not required; (4) the pollutants are converted into a saleable agricultural fertilizer; (5) the process has low capital and operating cost requirements. The history of the process is shown with a summary of the work that is presently underway. All of the current work is for the purpose of fine tuning the process for commercial usage. It is believed that with current testing and improvements, the process will be very competitive with existing processes and it will find its place in an environmental conscious world.