US 5,686,053 A · Wet-type flue gas desulfurization plant and method making use of a solid desulfurizing agent

Abstract

A wet-type flue gas desulfurization method and plant making use of a solid desulfurizing agent in which exhaust gas exhausted from a combustion apparatus such as a boiler is brought into contact with absorbing liquid to absorb sulfur oxide from the exhaust gas into the absorbing liquid followed by neutralization of the absorbing liquid containing the sulfur oxide thus absorbed. The solid desulfurizing agent is selectively retained in an absorbing liquid neutralizing zone and the absorbing liquid, containing water as a main constituent and solid products formed from the absorbed sulfur oxide, is selectively removed from the neutralizing zone. In the neutralizing zone the upward flow of the absorbing liquid, optionally augmented by an upward flow of air or water, forms a fluidized bed of limestone particles, thereby preventing coating of the limestone by gypsum and thereby retaining reactivity of limestone. According to the present invention, coexistence of Al and F in the absorbing liquid seldom deteriorates the desulfurizing performance. Further, it is possible to reduce power and cost required to grind limestone and to achieve a higher desulfurizing performance.

Claims28

Dependent claims

A wet-type flue gas desulfurization method for removing sulfur oxides from an exhaust gas, said method comprising:

contacting the exhaust gas with a water-containing absorbent in an absorbing zone to absorb the sulfur oxides thereby forming an acidic water-containing liquid;
collecting the acidic water-containing liquid in a pool below the absorbing zone;
passing the collected acidic water-containing liquid through a bed of fluidized particles of a solid desulfurizing agent contained within a neutralization zone, for neutralization of the acidic water-containing liquid by reaction with the desulfurizing agent particles to form solid reaction product particles in an admixture with the water-containing absorbent, while agitating the neutralization zone to prevent the desulfurizing agent particles from being coated with reaction product;
physically separating by size the admixture of water-containing absorbent and the solid reaction product particles from the desulfurizing agent particles, said desulfurizing agent particles having a particle size sufficiently larger than the reaction product particles to allow physical separation of the two types of particles;
and
recirculating at least one portion of the separated admixture to the absorbing zone for use in said contacting step while leaving the desulfurizing agent particles within said neutralization zone.

3 more elements

A wet-type flue gas desulfurization plant for removing sulfur oxides from an exhaust gas, said apparatus comprising:

contact means for contacting the exhaust gas with water-containing absorbent in an absorbing zone to absorb the sulfur oxides and thereby form an acidic water-containing liquid;
a tank below the absorbing zone for collecting the acidic water-containing liquid in a pool;
neutralization means, including a bed of a particulate desulfurizing agent within a neutralization zone, for circulating the acidic water-containing liquid through said bed to neutralize the acidic water-containing liquid by contact with the desulfurizing agent to form a reaction product as particles in an admixture with the water-containing absorbent, the particles of said desulfurizing agent having a particle size sufficiently larger than the reaction product particles to allow physical separation of the two types of particles;
fluidizing means for fluidizing said bed and for agitating the neutralization zone to prevent the desulfurizing agent particles from being coated with reaction product;
separation means for physically separating by size the admixture of reaction product particles and water-containing absorbent from the desulfurizing agent particles;
and
recirculating means for recirculating at least one portion of the separated admixture to the absorbing zone.

4 more elements

Dependencies are inferred from the claim text.

Wet-type flue gas desulfurization plant and method making use of a solid desulfurizing agent

Life of this patent

Wet-type flue gas desulfurization plant and method making use of a solid desulfurizing agent

Life of this patent

Abstract

Claims28