TH33520A - Process and gas treatment from smoke pipes - Google Patents

Abstract

DC60 (24/11/47) In the smoke gas treatment system, the adsorption tower (21), reheating unit (22), and fan (23) are arranged linearly on a vertical axis so that they act as at least part of the chimney for releasing the treated smoke gases into the atmosphere. In addition, in the smoke gas treatment process, the amount of ammonia injected into the nitrogen reduction step [nitrogen reducer (2)] and/or the amount of ammonium injected at the end point of the nitrogen reduction step is calculated so that there is an excess of ammonia or ammonia salts remaining in the smoke gases fed into the sulfur reduction step [adsorption tower (21)]. Thus, the size and cost of the equipment can be reduced. In the smoke gas treatment system, the adsorption tower (21), reheating unit (22), and fan (23) are arranged linearly on a vertical axis so that they act as at least part of the chimney. For the release of treated smoke gases from the smoke pipe into the atmosphere, in addition, in the smoke gas treatment process, the amount of ammonia injected into the nitrogen reduction step [nitrogen reducer (2)] and/or the amount of ammonium injected at the end point of the nitrogen reduction step is calculated so that there is an excess level in which ammonia or ammonia salts remain in the smoke gases fed into the sulfur reduction step [absorption tower (21)]. Thus, the size and cost of the equipment can be reduced.

Claims (5)

1. The flue gas treatment system consists of a nitrogen reduction step of injecting ammonia into the flue gas (A), which contains at least nitrogen oxides and sulfur oxides to decompose the nitrogen oxides present in the flue gas, and a sulfur reduction step of taking the flue gas out of the nitrogen reduction step into the adsorption tower (21), where it is brought into gas-liquid contact with the adsorption fluid (E) to remove at least sulfur oxides from the flue gas by adsorption into the adsorption fluid. Ammonia (B) is injected into the flue gas as needed at the end of the nitrogen reduction step, and the amount of ammonia injected in the nitrogen reduction step and/or the amount of ammonia injected at the end of the nitrogen reduction step is set so that there is an excess level so that ammonia or ammonium salts remain in the flue gas brought into the sulfur reduction step. In the region where the liquid (J) is more acidic than the adsorption fluid (E), it is atomized to prevent A conduit that allows ammonium to be easily released into the gaseous state is created at the terminal end of the adsorption column where the smoke gas is brought into gas-liquid contact with the adsorption fluid, where any remaining ammonia in the smoke gas that has been subjected to the sulfur reduction step is adsorbed in the adsorption column, preventing it from remaining in the smoke gas (D) that exits the adsorption column. 2. The fume gas treatment process as claimed in claim 1 shall be such that the amount of ammonia injected in the nitrogen reduction step shall be determined so that the concentration of ammonium remaining in the fume gas exiting the nitrogen reduction step shall not be less than 30 parts per million. 3. The fume gas treatment process as claimed in claims 1 or 2, which includes a heat recovery step of the fume gas exiting the nitrogen reduction step into the heat exchanger (24) on the upstream side of the said absorption tower and thus recover heat from the fume gas and where a leak-proof heat exchanger (85) of cell and tube structure is used as such heat exchanger. 4. The fume gas treatment process as claimed in claims 1 or 3, which also includes a heat recovery step for the intake of the fume gas from the nitrogen reduction step into the heat exchanger (24) on the upstream side of the absorption tower and thus recovers heat from the fume gas and where the amount of ammonia injected in the nitrogen reduction step and/or the amount of ammonia injected at the downstream end of the nitrogen reduction step is determined so that the concentration of ammonia remaining in the fume gas being injected into the heat exchanger exceeds the concentration of SO3 in the fume gas by 13 parts per million or more. 5. The process of treating the smoke gas as claimed in one of the claims 1-3, which includes the first dust removal step of bringing the smoke gas from the smoke to a dry electrostatic precipitator (5) on the upstream side of the said adsorption tower (21) and thus removing the dust present in the smoke gas, and the second dust removal step of bringing the smoke gas from the smoke to a wet electrostatic precipitator (32) on the downstream side of the said adsorption tower and thus removing the dust remaining in the smoke gas. (5 claims, 2 pages, 10 figures)