Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Patent
1995-01-04
1997-05-20
McMahon, Timothy
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
422 14, 252395, 252396, C23F 1112
Patent
active
056309856
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a (1) chemical formulation useful for treating water to inhibit corrosion and/or deposit formation, particularly useful to inhibit, prevent or control corrosion and/or deposit formation in water distribution piping and equipment and associated heat exchangers and also particularly useful for the prevention, control or inhibition of corrosion and of deposits in heat transfer equipment wherein water or steam is employed as a heat transfer medium and (2) process for using such chemical formulation. In a specific embodiment, the invention relates to the application of the formulation and process in cases where geothermal hot water and steam are used as the heat transfer medium.
A number of examples can be cited of industrial and other applications in which ground water (i.e., well water is employed as a heat transfer medium. For example, in some areas of the world, geothermal hot water and steam are available at underground depths such that they can be economically captured. In such areas, present day prices and pollution concerns associated with the use of fossil fuels make it practical to use geothermal heat to drive equipment such as electrical generation equipment.
Geothermal heat is increasingly being used for this purpose. Geothermal heat can also be used to provide hot utility water for other applications such as heating buildings or for driving chemical processes.
A typical "geothermic circuit" consists of a production well drilled into a suitable porous rock formation or aquifer no a depth sufficient to provide the required volume of water. The depth can vary considerably depending on the geological configuration of the surrounding strata. The well is usually provided with a submersible production pump, although in some cases, the water or steam pressure within the well is sufficient to force the water to the surface. At the surface, the geothermal hot water and/or steam is passed through one or a series of heat exchangers to produce hot utility water or steam for, by way of example, turbine powered electricity generation. After passing through the heat exchanger(s), the water is returned to the ground via a waste well drilled to a predetermined appropriate depth, thus completing the circuit.
Well water is also increasingly being employed as a heat transfer medium for air conditioning/heat pump systems. The same basic geothermal circuit is employed as that described in the preceding paragraph except that hot water is not employed.
A serious problem involved with the use of ground water as a heat exchange medium is that ground water is almost always high in mineral content which frequently leads to corrosion of the water distribution piping and heat exchangers. Such corrosion reduces the useful life of the system. Another serious problem is the formation of scale deposits in the system which also reduce the useful life and the efficiency of the systems by clogging the distribution pipes and the heat exchangers.
In general, particularly when geothermal hot water and/or steam is used, there are three principal problems, to wit: due to the direct attack by H.sub.2 S dissolved in the geothermal water or by naturally high sulfurous iron levels in the water; attack; and chemistry of the particular geothermal water being used.
The problems associated with the use of ground water are also encountered to a lesser or, sometimes, greater extent, depending upon the geographic area, with surface water, e.g., river water.
Prior art methods of controlling, preventing or inhibiting corrosion and scale deposition in water distribution equipment and associated heat exchangers, while reasonably effective in some cases, also have been less than optimal in some cases.
One known method has been to add a mixture of certain acrylates and phosphonates to the geothermal water. It has also been suggested to protect the metal surfaces by use of a film-forming amine-type product. While these techniques have proven fairly successful in some highly corrosive systems, it is still desirable to find other tech
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patent: 5248438 (1993-09-01), Perez
Rycroft Christopher P.
Williams Dennis C.
Buckman Laboratories International Inc.
McMahon Timothy
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