Investigations of organic inhibitors for silica scale control in geothermal brines

Geochemistry of geothermal fluids and well scales, and potential for mineral recovery

A process and apparatus for desalinating seawater or brine and purifying water which contains minerals, salts, and other dissolved solids while simultaneously generating power. The salinous water is heated in a boiler to form steam and a concentrated brine. The concentrated brine is removed from the boiler, the steam produced in the boiler is washed with fresh water to remove trace salts and inorganic materials, and water bearing trace salts and inorganic materials are returned to the boiler. The washed steam is expanded across a turbine to generate electrical or mechanical power which is utilized as a product. The steam exhausted from the turbine is collected and condensed, and one portion of the condensed water is utilized as a fresh water product and another portion of the condensed water is used as the wash water to wash the steam produced in the boiler. Energy efficiency is improved by heat exchanging the hot concentrated brine against the salinous feed water or by flashing the brine to produce steam. Boiler scaling and corrosion may be controlled by feed water pretreatment. By utilizing distillation combined with power generation, demand for fresh water and power can be satisfied simultaneously.

Process for desalinating water while producing power

The static mixing element in a flow channel (7) has at least two deflectors (30) disposed on mountings (20) at a distance from the channel wall. The deflectors form an angle W of from 10° to 45° to the main flow direction Z. They have different orientations and the projection FZ of the deflectors in the main flow direction amounts to from 5% to 50% of the channel cross-section F. Cross-flows providing very efficient transverse mixing are therefore produced in a simple manner. When dispensing tubes (20, 21) are used as mountings a very effective mixing device is provided.

Static mixing element having deflectors and a mixing device

A geothermal energy conversion system extracts heat from a heat source below the Earth's surface, which has a temperature above that of a fluid circulating through a closed system. A geothermal well and an enclosed well casing define a space that extends from ground level to the heat source. A heat exchanger is in thermal communication with the heat source, and a system of valves and at least one pump is in fluid communication, through the space within the well, with the heat exchanger. The system of pumps and valves regulates at least one of the flow rate or the pressure of the fluid so that the fluid vaporizes within the heat exchanger, the rate of vapor production in the heat exchanger is set at a predetermined value, and build-up of liquid within the heat exchanger is controlled.

Method and apparatus for steam generation from isothermal geothermal reservoirs

A method is provided for combining a high pH steam condensate with a flow of an acidic geothermal brine from which the steam is extracted so as to inhibit the formation of suspended particulate matter by the chemical combining of impurities in the condensate and brine. The method includes acidifying the steam condensate, preferably by hydrochloric acid, to reduce the pH to between about 7 and about 5.5 and then permitting the acidified condensate to outgas such volatiles as hydrogen sulfide and carbon dioxide before combining the condensate with the brine, formation of such insolubles as heavy metal sulfides and calcium carbonate being thereby inhibited. In a silica crystallizer stage in which flashed brine is contacted with a silica seed material to cause silica removal from the brine, the treated condensate is combined with the brine in a low pressure crystallizer upstream of brine clarification and reinjection stages. Part of the treated condensate is flowed to various pumps in the geothermal brine power production system to purge pump seals and prevent pump scaling and excessive wear.

Acidifiction of steam condensate for incompatibility control during mixing with geothermal brine

An injection nozzle especially useful for injecting corrosive acids into geothermal brines and the like comprises a bullet-shaped hydrofoil injection housing, a tubular manifold conduit connected thereto, preferably such that the axis of said manifold conduit and hydrofoil intersect at right angles, and a plurality of injection tubes emanating from said hydrofoil in a direction opposite that of the point of the bullet.

Hydrofoil injection nozzle

NORMs are inhibited or prevented from precipitating with scale produced by a hot aqueous solution by adding multiple portions of a crystal structure modifier to the aqueous solution as it cools before and during removal of silicon containing components by precipitation. Preferred crystal structure modifiers include polyacrylate crystal structure modifiers and phosphonomethylated amines.

Control of scale deposition in geothermal operations

Method for the production of useable steam and non-toxic solids from geothermal brine

A process for reducing the concentration of fine, residual solids still remaining suspended in clarified geothermal brine overflow from a primary brine clarification stage in which hot, flashed, silica-rich geothermal brine, containing suspended silicious material, is gravity separated, comprises flowing the brine overflow from the primary clarification stage into a closed secondary clarifier vessel having an internal reaction well. Capacity of the secondary clarifier vessel provides a brine residence time in the vessel of between about 45 and about 150 minutes, the brine residence time in the reaction well being between about 10 and about 20 minutes. Brine in the vessel is blanketed with steam flashed from the brine to exclude air from the vessel. In the reaction well, the brine is contacted with a flocculating agent, preferably a cationic polyacrylamide having a molecular weight of at least about 1 million, in an amount of between about 0.25 and about 2 parts per million. An underflow slurry of silicious material and brine is discharged from the bottom of the vessel, an amount of such underflow slurry is recirculated back into the reaction well causing the solids concentration in the well to be between about 0.5 and about 3 weight percent. A secondarily clarified brine overflow from the secondary clarifier vessel has a concentration of fine, silicious material remaining suspended therein that is substantially reduced over the concentration of such material suspended in the brine overflow from the primary clarification stage.

John L. Featherstone

Papers

Acidifiction of steam condensate for incompatibility control during mixing with geothermal brine

Hydrofoil injection nozzle

Control of scale deposition in geothermal operations

Method for the production of useable steam and non-toxic solids from geothermal brine

Process for reducing the concentration of suspended solids in clarified geothermal brine