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Show The superheaters had quite a good distance between the panels, but no coal mills or coal facilities were installed. The guaranteed steam capacities were then 190 tons/hour (220 peak load) with oil, and the manufacturer also guaranteed 120 tons of steam/hour when firing coal. In 1979, when the price difference had grown big between oil and coal, and also for safety during lockout times (wartime), it was decided to ask the local authorities for permission to convert the two small units. After the positive reply in the spring of 1980, it was decided to convert as soon as possible. The demands from the local authorities were to fire coal with maximum 0.8% S by weight and the other demands were: 3 3 a) Maximum 35 mg/Nm particle emissions as measured (50 mg/Nm average over a month). b) NO emission as low as possible. x r c) To emit as low noise levels and dust as possible. During the spring of 1980 the necessary equipment to fire coal was bought. Picture No. 3 shows the principal arrangement before the conversion and Picture No. 4 shows it after. As you will see from Picture No. 4 the new equipment for the boiler consists of six new coal/oil burners, 4 coal feeders and 4 mills. Picture No. 8 shows the new millhouse and the new parts of the boiler in colour. The furnace got 18 new steam soot blowers and a de-asher. To raise the efficiency, a district heating economizer (appr. 2.5 MW) was installed in the stack gas between the new electrostatic precipitator and the induced draft fans. The firms that got the different contracts were: 1. Coal conveyors Vretstorp-Verken AB Sweden 2. Coal hoppers Granges Hedlund Sweden 3. Mills, feeders, de-ashers PHI Great Britain 4. Firing equipment Peabody Holmes Ltd. Great Britain 5. Sootblowers Clyde Blowers Ltd. Great Britain 6. Electrostatic precipit. Flakt Industries Sweden 7. Economizer Generator AB Sweden Subcontractors to Peabody Holmes Ltd. 5-5 |