Internal water

S. A. Eisher and G. Otten, Proceedings of the 42nd International Water Conference, Engineering Society of Western Peimsylvania, Pittsburgh, 1981. 

Oil-Based Muds. Oil-based drilling fluids have diesel or mineral oil (11) as a continuous phase with both internal water and soHd phases. 

B. A. Demsey and L. WiUnow, Proc. 47th International Water Conference, Pittsburgh, Pa. (1986). 

J. M. Simonson and D. A. Palmer, "An Experimental Study of the VolatiUty of Ammonium Chloride from Aqueous Solutions to High Temperatures," Proceedings of the 13 th International Water Conference, Pittsburgh, Pa., Oct. 21—23, 1991, p. 253. 

L. D. Martin and W. P. Banks, "Electrochemical Investigation of Passivating Systems," Proceedings of the 35th International Water Conference,... 

Environment Internal Water contaminated with sulfur compounds, 70-90°F (21-32 C)... 

The reason for using feed heating to set the entry feed water temperature at a level T, above the condenser temperature is that Tb must exceed the dewpoint temperature Tjp of the exhaust gases. If is below Tjp then condensation may occur on the outside of the economiser tubes (the temperature of the metal on the outside of the tubes is virtually the same as the internal water temperature because of the high heat transfer on the water side). With Tb > Tjp possible corrosion will be avoided. 

The body cylinder is usually cast iron with integral internal water jackets for cylinder wall cooling. These water jackets are tested for tightness. 

Tarzwell, C. M., Proc. 29th International Water Conference, Engineers Society of Western Pennsylvania, 1 (1968)... 

They can only carry out these functions consistently and efficiently if the feedwater (FW) and boiler water (BW) chemistry and the overall boiler operation are properly controlled. Thus, over the years, in addition to improvements in engineering design and practice, many different forms of external water treatment processes and internal water treatment programs have been developed. 

Water treatment for utility power boilers must be first class and generally necessitates extremely sophisticated pre- and post-boiler treatment processes. Internal water chemistry usually rellies on the use of caustic-free, phosphate treatment or all-volatile treatment (AVT) programs. 

The process of heating water usually produces sludge and sediments (primarily noncrystalline precipitated salts) in the boiler s waterside dmms and tubes. (Sludge production may be deliberately encouraged in certain forms of internal water treatment programs.)... 

Inspecting all associated pretreatment equipment, pumps, tanks, and valves also, all internal water surfaces whenever a boiler, condenser, FW heater, or other item of equipment is opened... 

As a consequence, highly rated boilers require higher quality, preboiler water treatment and very careful attention to the internal chemical treatments used and the overall internal water chemistry. 

The more extensive use of pretreatment equipment generally is a commendable approach, although it is difficult to externally overtreaf boiler MU and FW, it also is pointless to spend limited capital resources installing sophisticated equipment to provide high-purity water and then to subsequently add dissolved solids back into the FW or BW with an inappropriate, internal chemical program. Both external and internal water treatment programs must be compatible and mutually beneficial ... 

When considering the need for capital pretreatment equipment, sufficient care should be taken not to propose any particularly sophisticated external or internal water treatment regimen that of itself creates restrictive operational BW control limitations—where boiler design, steam usage, and common sense dictate no necessity for such limitations to be imposed. The overall water treatment program should not be overdesigned but should properly match the needs of the project. 

A failure to install a necessary softener is ultimately reflected in higher bills for maintenance, repairs, and water treatment chemical products and services. Scaling can still occur with soft, lean waters, and the cost of additional fuel over a year probably would pay for several water softeners. In addition, the control of internal water chemistry becomes more difficult than it might otherwise be, which places an additional operational burden upon the facility. 

Thus, a failure to properly balance and control various external and internal water chemistry parameters may lead to one or more corrosion mechanisms occurring, including several forms involving oxygen. Many types of corrosion are of themselves unfortunately relatively common phenomena, and the mechanisms also are common to all sizes and designs of boiler. 

From the earliest days of steam production, it was recognized that a complementary combination of external and internal water treatment was a vital requirement of boiler operating practice. The justification for investment in external conditioning was (and continues to be) based... 

With lower heat-flux ratings and higher ratios of internal water volume to heating surface than is the norm today, complex external treatment was not always necessary where deemed necessary, it was often limited to basic sedimentaion or filtration techniques employing inorganic coagulants and flocculants, typically followed by the use of natural zeolites (see sections 9.2.3.1 and 9.2.5 for additional information). 

The limitations of modem boilers to accept the volumes of sludge produced because of the limited internal water space available. 

Where chelant or chelant/polymer programs are used, typically, instructions are given to maintain a specific chelant reserve. In practice, this is not always achievable because of test method limitations and internal water chemistry constraints. 

Where equipment has been in operational use for some length of time (say, several years), and despite the use of appropriate internal and external water treatment programs, it may become necessary to provide some form of basic offline cleaning to restore heat-transfer efficiency. For smaller HW and LP steam FT boilers, especially where external water treatment is minimal and internal water treatment is limited by cost considerations, the frequency of offline cleaning may be annual, perhaps at the end of the winter heating season. 

Cathodic protection equipment has been used very successfully in water tanks and HW and steam boilers as anticorrosion devices for 100 years or more. Such equipment comes in many shapes and sizes, and comprises a sacrificial anode of either zinc or magnesium alloy, either bolted directly to a suitable internal water-wetted (cathodic) metal surface, or self-contained by enclosing the anode with a suitable cathode (such as a silver plated base metal). Usually several devices are required for any boiler, more for larger units and less for smaller ones, and these require replacement every one to two years. 

Hann, W.M. Keller, L.H. Sanders, T.W. Weinstein, B. Towards Field-Friendly Traceable Polymeric Dispersants. 58th International Water Conference, USA, Nov 1-5, 1997. 

Kinghorn, Patrick H. Haas, William E. (Ecolochem, Inc.). Low Level Deoxygenation of Boiler Makeup Water Using Gas Transfer Membranes. Pittsburgh International Water Conference, USA, 1999. 

Robinson, Jim. Internal Water Treatment for Industrial Steam Plants. Industrial Water Treatment, Tall Oaks Publishing, Inc., USA, November/Decemberl992. 

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