Limestone-based sorbent agglomerates for removal of sulfur compounds in hot gases and method of making

• US 4,387,653 A
• Filed: 10/05/1981
• Issued: 06/14/1983
• Est. Priority Date: 08/04/1980
• Status: Expired due to Fees

• Current Assignee: Engelhard Corporation (BASF SE)
• Original Assignee: Engelhard Corporation (BASF SE)
• Inventors: Voss, Kenneth E.
• Primary Examiner(s): Favors, Edward G.
• Application Number:
  US06/308,868
• Time in Patent Office: 617 Days
• Field of Search: 110/342, 110/343, 110/344, 110/345, 252/189, 431/7, 431/170, 44/15 R
• US Class Current: 423/230
• CPC Class Codes: B01D 53/508 by treating the gases with solids
• CPC Class Codes: B01D 53/523 Mixtures of hydrogen sulfide and sulfur oxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/2803 Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
• CPC Class Codes: B01J 20/3021 Milling, crushing or grinding
• CPC Class Codes: B01J 20/3028 Granulating, agglomerating or aggregating
• CPC Class Codes: B01J 20/3042 Use of binding agents; addition of materials ameliorating the mechanical properties of the produced sorbent
• CPC Class Codes: B01J 20/3433 of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425
• CPC Class Codes: B01J 20/3458 in the gas phase
• CPC Class Codes: F23C 10/002 for pulverulent solid fuel F23C10/005 - F23C10/32 take precedence

Abstract

Sulfur-containing compounds such as hydrogen sulfide and sulfur oxides arising from gasification or combustion of organic fuels such as coal may be removed from the hot gases by attrition resistant, highly reactive limestone-based sorbent agglomerates. The agglomerates are formed by crushing and powdering naturally occurring limestone into grains of fine particle size and binding the powdered limestone grains with a binder that is stable at high temperature, for example a colloidal grade of attapulgite clay. Volatile liquid is added to the mix of binder and powdered limestone to form a paste-like mixture, which is then agglomerated in compression-type agglomerating equipment to form spheroidal agglomerates having good green strength. In fluidized bed combustion applications, these agglomerates have attrition resistance equivalent to conventional natural limestone granules and are far more reactive in terms of sulfur pickup.

Claims

1. In a process for fluidized bed combustion of sulfur containing fuel such as coal or heavy oil, wherein said fuel generates sulfur oxides in the flue gas stream upon combustion, and limestone is added to said bed to react with said sulfur oxides to remove them from the flue gas stream, the improvement which comprises enhancing the removal of sulfur oxides by utilizing said limestone in the form of agglomerates comprising fine grains of naturally occurring, uncalcined limestone and a cementitious clay selected from the group consisting of attapulgite, sepiolite, smectite and mixtures thereof in binder-effective amount.

6. The process of claims 1, 2, 4, or 5 wherein at least a portion of said agglomerates are recovered, regenerated and recycled to further charge of fuel after initial use for removal of sulfur compounds.

2. In a process for fixed bed combustion of sulfur containing solid fuel such as coal, wherein said fuel generates sulfur oxides in the flue gas stream upon combustion, and limestone mingled with the coal in said bed to react with said sulfur oxides to remove them from the flue gas stream, the improvement which comprises enhancing the removal of sulfur oxides by utilizing said limestone in the form of agglomerates comprising finely powdered, naturally occurring, uncalcined limestone and cementitious clay selected from the group consisting of attapulgite, sepiolite, smectite and mixtures thereof in binder-effective amount.

3. The process of claim 2 wherein said solid fuel is coal.

4. In a process for removing hydrogen sulfide from gases, the improvement which comprises utilizing agglomerates comprising fine grains of naturally occurring, uncalcined limestone and a cementitious clay, selected from the group consisting of attapulgite, sepiolite, smectite and mixtures thereof, in binder-effective amount.

5. In a process for removing sulfur oxides from gases, the improvement which comprises utilizing agglomerates comprising fine grains of naturally occurring, uncalcined limestone and a cementitious clay, selected from the group consisting of attapulgite, sepiolite, smectite and mixtures thereof, in binder-effective amount.