REMOVING ASH FROM PULVERIZED COAL

• Main Author: TODD DAVID HELLEWELL
• Format: Patent
• Language: English
• Published: 22.11.1984
• Edition: 3
• Subjects: BLASTING; COMBUSTION APPARATUS; COMBUSTION PROCESSES; CRUSHING, PULVERISING, OR DISINTEGRATING; CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; FEEDING FUEL TO COMBUSTION APPARATUS; HEATING; LIGHTING; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLIDMATERIALS OR FLUIDS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROMSOLID MATERIALS OR FLUIDS; MECHANICAL ENGINEERING; MILLING GRAIN; OTHER SEPARATING BY DRY METHODS APPLICABLE TO BULK MATERIAL,e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL; PERFORMING OPERATIONS; PREPARATORY TREATMENT OF GRAIN FOR MILLING; SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATICTABLES OR JIGS; SEPARATING SOLIDS FROM SOLIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS; SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATICTABLES OR JIGS; SEPERATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, ORSIFTING OR BY USING GAS CURRENTS; SORTING; TRANSPORTING; WEAPONS

A system for pulverizing coal to be burned in a furnace (20), where nearly all of the coarse ash particles are removed from the coal prior to its introduction to the furnace. The system includes a pulverizing mill (10) having a first classifier (12) in its outlet for separating some of the large, heavy particles and returning them to the pulverizer. A second classifier (16) is connected to the first classifier, and includes a curved duct (16) wherein the solid particles being carried in an airstream are thrown outwardly against an outer wall. A skimmer blade (78) extending through the outer wall skims off a percentage of the large, heavy particles, the percentage depending on how much coarse ash the coal stream contains. The rest of the coal particles are conveyed to a furnace and burned therein. The separated large, heavy particles are passed through an ionizer (30) and then through an electrostatic separator (34), where the inorganic particles are separated from the coal particles. The coal particles can then be conveyed to the furnace or sent back to the pulverizer for further grinding.