The "Comprimo Ammonia Destruction System" for Claus Sulfur Recovery Units (SRU's) has been provided for many years in the U.S.A. and Canada by Goar, Allison & Associates, Inc. (GAA) .  The Comprimo system for handling NH3 in SRU feed gas has only recently received general acceptance in North America, although it has enjoyed wide application and success in Europe and Japan for a number of years. This patented system for the effective combustion of NH3 in acid gas streams was developed by Comprimo b.v. Engineers and Contractors of Amsterdam, The Netherlands and is licensed by Jacobs Nederland, B.V.

The system long used in the U.S.A. and Canada for the destruction of ammonia (from a Sour Water Stripper overhead gas stream) in a Claus Sulfur Recovery Unit involves a controlled split of the "clean" acid gas (with no NH3 or hydrocarbons) between the front and side of the Reaction Furnace. This is commonly called the "Front/Side Split" system. Destruction of NH3 is dependent on maintaining near stoichiometric oxygen in the front section of the furnace where the Sour Water Stripper (SWS) off-gas is introduced. The main problem with this system is control of the proper split of the "clean" acid gas stream, especially with varying feed rates and com- positions of the SWS off-gas and the "clean" acid gas from an Amine Plant. In practice this split often deviates far from the theoretical process requirement, and ammonia destruction is incomplete. This results in solids deposition, corrosion, and eventual plugging of equipment and sulfur rundown legs with solids and debris. A plant shutdown may be required to correct the problems or clean debris out of the unit. If severe corrosion has occurred, some equipment repairs or replacement may be required.

The "Comprimo Ammonia Destruction System" solves the main problem with the old system, i.e., the split of "clean" acid gas to the side of the Reaction Furnace. In the "Comprimo Ammonia Destruction System", the Reaction Furnace is provided with an advanced design "Duiker" burner, which handles the SWS off-gas, all of the "clean" acid gas, and the SCOT unit recycle gas (if applicable) all in one burner. All acid gas streams and the combustion air are fed to the main burner located on the front of the Reaction Furnace. It is imperative that the clean acid gas stream be preheated to at least 170-180°F before mixing with the SWS off-gas and entering the burner. Using the Comprimo system with the special "Duiker" burner eliminates the need to split part of the "clean" acid gas stream to the side of the Furnace. The special burner achieves very efficient mixing of the air with the acid gas streams and very thorough destruction of the ammonia.  The burner is an efficient mixing, high pressure drop (about 0.5 psi greater than usual), custom designed burner. The burner is available only from LD Duiker in Holland, which is also the main manufacturer for inline burners for SCOT Units. LD Duiker b.v. is a highly sophisticated and very reputable burner manufacturer.

The patented Comprimo system has been installed on about 70 Sulfur Recovery units worldwide. Of these plants, over 40 are handling sig- nificant quantities of NH3 on a daily basis. The units range in size from about 20 MTPD to about 270 MTPD (MTPD = metric tons/day) .Most of these units are installed in Western Europe and Japan. The first unit designed with this special system was put on stream in 1969. In North America eight of these systems are in operation and six are in the design or construction stage.

Comprimo has tested their system using as high as 28 mol% NH3 in a combined feed (Amine acid gas plus SWS off-gas), and found essentially total NH3 destruction. One unit in the U.S.A. has operated with about 20 mol% NH3 in the combined acid gas feed, and successfully passed the perfor- mance test at 25 mol% NH3 in the combined acid gas feed. Many of these plants operate with more than 10 mol% NH3 in the combined acid gas feed. The Comprimo technology for destroying NH3 in Sulfur Plants is very well established and commercially proven.

The Comprimo technology is available in the U.S.A. and Canada under license from GAA Engineered Systems, Inc., a licensing company formed by Goar, Allison & Associates, Inc. The Comprimo system also employs certain special design parameters and features in the Reaction Furnace. The Reaction Furnace may be built by any reputable and experienced vendor in the U.S.A., but it must incorporate certain critical design features to assure complete destruction of the NH3. Of course, the same features that favor the destruction of NH3 (better burner mixing, longer Furnace residence time, etc.) also enhance the Claus "free-flame" or "thermal" conversion step in the Reaction Furnace, resulting in a somewhat better overall sulfur conversion than otherwise experienced in Claus Sulfur Plants.

For more information or a specific application, please contact GAA