20171018 Atmospheric and Vacuum Distillation Questions

1) Reduce flue gas temperature； 2) Appropriately reduce the excess air coefficient of the heating furnace ； 3) Use high-efficiency burners ； 4) Reduce heat loss from the furnace wall ； 5) Set up and improve the control system ； 6) Strengthen the technical management of heating furnaces and improve operational skills.

I. Minimize the physical heat carried away by the flue gases and fully recover this heat. 1. Recover the heat from the flue gas, and use this heat to preheat the air and gas ； 2. Reduce the temperature of the flue gas exiting the furnace as much as possible, while ensuring consistent production levels and heating quality ； 3. The burned and poorly heat-storing regenerative balls should be replaced promptly to ensure their normal heat-storing capacity. II. Ensure sufficient air to allow the gas to burn fully. 1. The heater must adjust the air-to-coal ratio appropriately based on the calorific value of the gas, in order to reduce heat losses caused by incomplete chemical and mechanical combustion ； 2. Minimize the air excess coefficient to prevent excess air from absorbing large amounts of heat and generating additional flue gas that carries away heat. 3. Control the furnace pressure properly to prevent negative pressure from drawing in cold air into the furnace. III. Reduce various heat losses within the furnace. 1. Insulate the furnace rib tubes; repair any areas where the insulating material has fallen off as soon as possible ； 2. Where conditions permit, the use of air-cooled slides can completely eliminate heat losses associated with water cooling or vapor cooling ； 3. By using new types of high-efficiency, energy-saving furnace construction materials to improve the thermal insulation properties of the furnace lining, it is possible to reduce heat storage in the furnace walls and minimize heat losses caused by heat escaping through those walls. IV. Strengthen the heat transfer process to the billets as much as possible, shorten the heating time and the waiting time at a certain temperature, thereby increasing the furnace’s productivity. 1. In the heating section, a large amount of gas is used for heating in order to increase the combustion intensity of the gas and achieve rapid heating ； 2. Raising the temperature of the steel billets entering the furnace can reduce the fuel consumption rate; the hot charging and hot delivery process can completely eliminate heat losses resulting from waiting for the billets to reach the appropriate temperature. V. Ensure the tightness of the furnace as much as possible. 1. By using a side-loading and side-unloading method for loading and removing steel, the heat dissipation area of the furnace door can be minimized ； 2. During the production process, manholes and all slag removal furnace doors must be tightly sealed with refractory bricks to prevent fire leakage ； 3. During the heating process, it is strictly prohibited to burn steel with the furnace door open ； At the same time, the furnace door should be closed promptly during the rolling process; it should not be opened frequently unless necessary, in order to reduce unnecessary heat loss. VI. Reduce radiation heat loss from the furnace surface. 1. The surface of the furnace lining should be coated with a special refractory coating to prevent the loss of heat radiation ； 2. Heating furnaces that use external heat storage tanks must have an insulating layer applied to their surface in order to reduce thermal radiation from the tank. VII. Strengthen production organization and management, coordinate upstream and downstream processes to ensure orderly and balanced production, and minimize the time spent in holding materials for rolling or running the furnace idle. 1. Increase the rolling mill’s operational efficiency to achieve stable and high production levels ； 2. When production is not at full capacity, centralized production and centralized shutdown of the furnaces should be adopted to organize production ； 3. Agree on the product specifications, and arrange the rolling tasks of the same specification to be carried out during the same time period as much as possible, in order to reduce preparation time as well as the number of times rolls need to be replaced or molds need to be changed ； 4. Try to schedule the downtime of other rolling mill equipment during the same period as the time when the heating furnace is waiting for the appropriate temperature.

Answer: 1) Reduce the flue gas temperature； 2) Appropriately reduce the excess air coefficient of the heating furnace ； 3) Use high-efficiency burners ； 4) Reduce heat loss from the furnace wall ； 5) Set up and improve the control system ； 6) Strengthen the technical management of heating furnaces and improve operational skills.