摘要:
A method and apparatus for reducing discharges into the atmosphere of mercury pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile mercury pollutants, such as elemental mercury and mercury oxides. Preferably, the feed meal is heated to a temperature of at least 175° C. The gases that are driven off flow are then cooled to condense the mercury pollutants causing them to be adsorbed on carbon particles injected into the gas flow. The carbon particles containing the condensed mercury pollutants are then filtered out of gas flow, for example, using a fabric filter. The gas flow may be burned to destroy other volatile pollutants such as hydrocarbons and/or ammonia.
摘要:
A method and apparatus for reducing air pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile compounds, such as organic materials and salts of ammonia. Preferably, the feed meal is heated to a temperature of at least 350° F. The gases that are driven off flow to the precalciner where they are combusted and rendered harmless. Heat is provided by diverting at least a portion of the exhaust gases from the cement pyroprocessing kiln to the special heater. The raw feed meal is indirectly heated using a heat exchange wall between the feed meal and the kiln exhaust gas flow. In addition, a base-containing material such as lime or precalcined feed meal, may be added to the raw feed before treatment meal to promote the breakdown of inorganic ammonium compounds, thereby releasing gaseous ammonia which is also destroyed upon subsequent combustion. Hot precalcined meal may also be used to provide some of the heat required to heat the raw feed meal in the special heating chamber.
摘要:
A method and apparatus for reducing air pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile compounds, such as organic materials and salts of ammonia. Preferably, the feed meal is heated to a temperature of at least 350° F. The gases that are driven off flow to the precalciner where they are combusted and rendered harmless. Heat is provided by diverting at least a portion of the exhaust gases from the cement pyroprocessing kiln to the special heater. The raw feed meal is indirectly heated using a heat exchange wall between the feed meal and the kiln exhaust gas flow. In addition, abase-containing material such as lime or precalcined feed meal, may be added to the raw feed before treatment meal to promote the breakdown of inorganic ammonium compounds, thereby releasing gaseous ammonia which is also destroyed upon subsequent combustion. Hot precalcined meal may also be used to provide some of the heat required to heat the raw feed meal in the special heating chamber.
摘要:
A method and apparatus for reducing discharges into the atmosphere of mercury pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile mercury pollutants, such as elemental mercury and mercury oxides. Preferably, the feed meal is heated to a temperature of at least 175° C. The gases that are driven off flow are then cooled to condense the mercury pollutants causing them to be adsorbed on carbon particles injected into the gas flow. The carbon particles containing the condensed mercury pollutants are then filtered out of gas flow, for example, using a fabric filter. The gas flow may be burned to destroy other volatile pollutants such as hydrocarbons and/or ammonia.
摘要:
The liquid cooling spray in a gas conditioning chamber is modified by the addition of an alkali to scrub sulfuir dioxide and other acid forming gases and a separation unit to remove particles that may contain either unreacted alkali or salts of the acid forming gases. A slurry of fine particles of hydrated lime is injected into the liquid coolant under conditions that result in kernels of controllable size that contain the alkali or salts from reactions with the acid forming gases. The modified cooling liquid provides for a high sulfur dioxide collection efficiency at a low molar ratio of alkali to sulfur, while the specified kernel size range allows fbr efficient removal of the kernels from the gas.
摘要:
A method is provided for abating acidic contaminants, such as sulfur dioxide and hydrogen chloride, in exhaust gases while minimizing the formation of visible plumes of ammonium salts proximate to the outlet of the exhaust stack by injecting a spray of an alkaline liquid, such as sodium hydroxide or potassium hydroxide, into the contaminated exhaust gases wherein the pH of the alkaline liquid is high enough, i.e. greater than a pH of about 11, so that the acidic contaminants preferentially react with the alkaline liquid rather than the ammonia in the gases, thereby minimizing formation of visible plumes of ammonium salts.
摘要:
An air pollution control system using a novel control system is disclosed. The control system is particularly useful with a gas conditioning tower ("GCT") which uses a spray from a two-fluid nozzle to cool hot process gases prior to flowing to an electrostatic precipitator. A first control loop, employing, for example, a temperature feedback control system, is used during normal operation of the system, and an override control loop is used to protect the electrostatic precipitator from overheated gases which may be diverted in the case of a plant upset. The override control loop adjusts the spray based on a calculation of the spray characteristics needed to meet the new GCT conditioning requirements. In another aspect the present invention relates to a method and apparatus for optmizing the spray from a two-fluid nozzle used in a GCT. In particular, the spray droplets are made larger when possible, thereby reducing the energy usage of the system. In yet another aspect of the present invention, the controller used in the air pollution control system directly regulates delivery pressure of the air compressor used as a source of compressed air for the two-fluid nozzle, for further energy savings.
摘要:
A venturi increases the velocity of contaminated gases and guides the gases past a high, extremely dense electrostatic field presented perpendicular to the gas flow and extending radially outward between a central, accurately sized disc electrode and the surface of the venturi throat. Downstream, charged particles are collected by a wet scrubbing process or electrostatic precipitator.
摘要:
A low-energy venturi pre-scrubber optimized for removing abrasive particles from a gaseous effluent is disclosed. While venturi scrubbers are efficiently used for at removing entrained particulates in air pollution control systems, they can be damaged due to the abrasive characteristics of entrained particles, such as silica particles greater than a micrometer in diameter. According to the present invention, high scrubbing efficiencies can be obtained in equipment that is not damaged by the abrasive particles by first removing the abrasive particles in a low-energy venturi, and then removing the remaining particles in a second scrubber. In addition to improving the lifetime and reducing the maintenance costs of the venturi, scrubbing fluids have fewer large particles, allowing their use in downstream components, such as evaporative coolers.