{"id":781,"date":"2025-02-04T09:00:42","date_gmt":"2025-02-04T09:00:42","guid":{"rendered":"https:\/\/www.espindesa.es\/?page_id=781"},"modified":"2025-03-12T13:00:56","modified_gmt":"2025-03-12T13:00:56","slug":"nox-abatement","status":"publish","type":"page","link":"https:\/\/www.espindesa.es\/en\/technologies\/nox-abatement\/","title":{"rendered":"NOx ABATEMENT"},"content":{"rendered":"

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    \n NOx ABATEMENT CATALYSTS\n <\/h1>\n <\/div>\n <\/div>\t\n <\/div>\n <\/section>[\/vc_column][\/vc_row][vc_row css=”.vc_custom_1737025291657{margin-top: 50px !important;}”][vc_column][vc_row_inner][vc_column_inner width=”1\/2″]
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    \n Overview\n <\/h3>\n

    \n NOx ABATEMENT CATALYSTS\n <\/h2>\n

    The environmental regulations adopted in most countries, require that the nitrogen oxides content of the tail gas, exhausted to the atmosphere from nitric acid plants or caprolactame plants, is kept below 50 ppmv or even less. To meet those strict limits, many different techniques have been proposed, but catalytic reduction is the most widely adopted.<\/p>\n

    The ESPINDESA technology for NOx abatement is based on the use of its own, or partner, selective catalyst.<\/p>\n\n <\/section>[\/vc_column_inner][vc_column_inner width=”1\/2″][vc_single_image image=”783″ img_size=”full” css=””][\/vc_column_inner][\/vc_row_inner][\/vc_column][\/vc_row][vc_row full_width=”stretch_row_content_no_spaces”][vc_column][vc_empty_space]

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    \n \"Comillas\"\n

    \n The heat evolved in the reaction increases the tail gas temperature by5 to 25\u00ba C depending on the NOx content of the tail gas.\n <\/p>\n <\/div>\n <\/section>[\/vc_column][\/vc_row][vc_row][vc_column][vc_empty_space height=”48px”][vc_column_text css=””]Ammonia reacts selectively with nitrogen oxides in the presence of oxygen. The chemical reactions which occur in the presence of an adequate catalyst are:<\/p>\n

    6NO + 4NH3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0 5N2 + 6H2O<\/p>\n

    6NO2 + 8NH3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0 7N2 + 12H2O NO + NO2 + 2NH3 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2N2 + 3H2O 4NO + O2 + 4NH3 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 4N2 + 6H2O<\/p>\n

     <\/p>\n

    The heat evolved in the reaction increases the tail gas temperature by5 to 25\u00ba C depending on the NOx content of the tail gas.<\/p>\n

    Temperatures below 180\u00b0 C must be avoided due to the risk of formation of ammonium nitrate-nitrite. Anyway, if due toa miss operation those salts deposit over the catalyst, ESPINDESA has developed procedures for regeneration “in situ” which restore the activity of the catalyst in few hours.<\/p>\n

    The operating pressure can range from atmospheric to 10 bar and the location of the catalyst can be either upstream or downstream the tail gas expansion turbine.[\/vc_column_text]\n

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    \n Process Description\n <\/h4>\n <\/section>[vc_column_text css=””]Gaseous ammonia is mixed with the tail gas in a Static Mixer. If the temperature of gas is lower than the optimum for the operation of the catalyst, the gas is preheated in a gas exchanger with the hot gas leaving the Reactor.A start up heater uses to be provided in those cases.<\/p>\n

    The mixture of ammonia and tail gas passes through the Reactor where the NOx reduction to nitrogen takes place.<\/p>\n

    The purified tail gas returns to the Nitric Acid Unit. Critical parameters are recorded and backed with alarms. An interlock contact is provided to close the ammonia feed in the event of a shutdown of the nitric acid plant.<\/p>\n

     <\/p>\n

    OPERATING REQUIREMENTS<\/p>\n

    Ammonia consumption<\/strong><\/p>\n

    The ammonia consumption depends of the NOx content in the tail gas but never is higher than 2-3% over the stoichiometric requirements.<\/p>\n

     <\/p>\n

    Effluents<\/strong><\/p>\n

    NOx\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0less than 50 ppm
    \nNH3\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0less than 5 ppm
    \n<\/strong><\/p>\n

    \u00a0<\/strong>[\/vc_column_text]\n

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    \n Process Flow Diagram\n <\/h4>\n <\/section>[vc_single_image image=”785″ img_size=”full” css=””][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

    [vc_row full_width=”stretch_row_content_no_spaces”][vc_column][\/vc_column][\/vc_row][vc_row css=”.vc_custom_1737025291657{margin-top: 50px !important;}”][vc_column][vc_row_inner][vc_column_inner width=”1\/2″][\/vc_column_inner][vc_column_inner width=”1\/2″][vc_single_image image=”783″ img_size=”full” css=””][\/vc_column_inner][\/vc_row_inner][\/vc_column][\/vc_row][vc_row full_width=”stretch_row_content_no_spaces”][vc_column][vc_empty_space][\/vc_column][\/vc_row][vc_row][vc_column][vc_empty_space height=”48px”][vc_column_text css=””]Ammonia reacts selectively with nitrogen oxides in the presence of oxygen. The chemical reactions which occur in the presence of an adequate catalyst are: 6NO + 4NH3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0 5N2 + 6H2O 6NO2 + 8NH3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00b7\u00b7\u00b7\u00b7\u00b7\u00b7>\u00a0\u00a0\u00a0\u00a0\u00a0 7N2 + 12H2O NO + NO2 + 2NH3 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":76,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-781","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/pages\/781","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/comments?post=781"}],"version-history":[{"count":5,"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/pages\/781\/revisions"}],"predecessor-version":[{"id":974,"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/pages\/781\/revisions\/974"}],"up":[{"embeddable":true,"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/pages\/76"}],"wp:attachment":[{"href":"https:\/\/www.espindesa.es\/en\/wp-json\/wp\/v2\/media?parent=781"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}