N e w Paten ts v

molecular weight C3-C8 hydrocarbons are in- jected into the reservoir and the production well is cyclically throttled. The production well flow rate is restricted until the bottom-hole pressure of the well has increased to an amount of about 30% to about 90% of the fluid injection pressure at the injection well. Thereafter, the production well is opened and oil is recovered therefrom as the bottom-hole pressure declines. The throttled production cycle may be repeated at appropriate intervals during the process.

4430256

REVERSE THERMODYNAMIC CHEMICAL BARRIER FOR

NUCLEAR WASTE OVER-PACK OR BACKFILL

Ro Rustum

/ 4 ~ . X//, .,~ , " - ~ / / / / /_ /</ / / / ,~ \Y/ANt , ~ / . ~ ,'..\"

Radioactive waste is stored surrounded by an overpack or backfill containing non-radioactive ions of the same radioactive elements as in the waste form. In place of an overpack of the ac- tinides, there can be used an overpack of the chemically similar lanthanides. Thus, there can be used in the overpack cesium and strontium containing aluminosilicates and cesium, stron- tium and lanthanide aluminates and silicates.

4430316

SCRUBBING SYSTEM YIELDING HIGH CONCENTRATION OF

HYDROGEN SULFIDE

Gerhard Ranke, Horst Weiss, Pfederal Republic Of Germana assigned to Linde Aktiengesel- lschaft

In a system for the separation of sour gases espe- cially hydrogen sulfide and carbon dioxide from a raw gaseous mixture e.g., hydrogen-containing in order to form a purified gaseous mixture, comprising scrubbing the gaseous mixture in a first scrubbing stage with a physical scrubbing li- quid e.g., methanol having a higher absorb- ability for hydrogen sulfide than for carbon dioxide, withdrawing from the scrubbing stage a first stream of scrubbing liquid loaded with hydrogen sulfide and carbon dioxide, and regenerating the loaded scrubbing liquid to form (a) a gaseous phase containing hydrogen sulfide, and (b) regenerated scrubbing liquid, the im- provement of scrubbing said gaseous phase con- taining hydrogen sulfide in a second scrubbing stage with a stream of scrubbing liquid capable of absorbing additional H2S, e.g., a CO2- depleted stream from an H2S enrichment column; and subjecting resultant second stream of scrubbing liquid loaded with hydrogen sulfide to a separation stage, preferably rectification, to form a bottoms of regenerated scrubbing liquid and an overhead of a gaseous phase rich in hydrogen sulfide irrespective of whether the raw gaseous mixture has a very low H2S concentra- tion.

4430719

CALCINATION CONTROL SYSTEM

Robert M Pearson assigned to Kaiser Aluminum & Chemical Corporation

• ~-~ ~ ~

CON,M~_

Nuclear magnetic resonance (nmr) is employed for the control of heat-input or feed rate of cal- cination and/or drying facilities. The residual volatile material content of the heat-treated material is monitored by nmr and the results ob- tained from the monitoring are employed to adjust the heat-input or feed rate to avoid overdrying or calcining of the heat-treated material. A computer, such as a micro- processor, may be utilized in combination with the nmr apparatus to provide instantaneous pro- cess control.