| Products – Washer programme | ||||||||||||||||||||||||||||||
| NOx separation from waste air Method of recovery of raw materials from waste gas without any origin of waste |
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| 4. Example of the use: | ||||||||||||||||||||||||||||||
| For pickling bath with a volume of 24 m³a closed process control has been implemented. The flow-rate of air drawn off by a fan is reduced with a measuring orifice plate. The drawn off air flow-rate can by adjusted continuously to a value of about 500 m³/h without any occurrence of negative effects to the pickling process. A NOx - loading is of about 1 000 – 5 000 ppm, in peak conditions 10 000 ppm at a NO/NO2- ratio of 1:10 . In this way the following raw gas doses are given : | ||||||||||||||||||||||||||||||
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| 4.1 Conventional NOx separation | ||||||||||||||||||||||||||||||
The drawn off air with NOx content which has to be purified is fed in five washers installed in series, with a diameter of 950 mm, filled with small solid bodies with a height of the filling bed of 5 600 mm. The washing circuit is in operation with the use of 20% caustic soda lye. In accordance with the process described under paragraph 2.1 – Alkaline washers the following reductions in NOx content take place in single columns: |
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Alternatively, it is possible to use also a smaller number of columns; in that case, however, it is necessary to use columns of a larger diameter. As a waste product it results an amount of 218.3 kg/d of NaNO2and 187.7 kg/d of NaNO3 respectively, i.e. in total of 406 kg/d of salts which shall be liquidated. For the process control from the practical point of view the concentration in the washing circuit shall not be chosen as a too high because it could result in crystallization and clogging. If we start from a maximum salt amount of 10% the flow-rate of waste water which has to be liquidated is 4 mł/d. Necessary caustic soda lye consumption is about 860 l/d for 25% solution. A reaction heat which should be dissipated is of 7.5 kW.The following operating costs result from it : |
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| The specified legal values of the purified gas 500 mg/m³ have been maintained. | ||||||||||||||||||||||||||||||
| 4.2 DGE processes : | ||||||||||||||||||||||||||||||
4.2.1 L-NOx-Process 4.2.2 G-NOx-Process 4.2.3 DGE - instrumentation |
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