Effect of carbon dioxide

Carbon dioxide is often ignored in steam systems. However, when absorbed in water, it forms carbonic acid, which can be corrosive to all parts of the steam and condensate system. Its potential presence is frequently overlooked in the design of heat exchangers, steam traps, condensate systems, deaerators, and water-treating systems. Most steam systems require continual addition of makeup water to replace losses. Makeup water must be adequately treated, by demineralization or distillation, to remove carbonates and bicarbonates. If these are not removed, they can be thermally decomposed to carbon dioxide gas and carbonate and hydroxide ions. The ions will normally remain in the boiler water, but the caron dioxide will pass off with the steam as a gas. When the steam is condensed, the carbon dioxide will accumulate since is is noncondensable) be passed as a gas by the steam trap or if the condensate and carbon dioxide are not freely passed by the steam trap, become dissolved in the condensate and form carbonic acid. If carbonic acid is formed it can have a pH approaching 4 and be very corrosive to copper and steel. Even if both the gas and condensate are passed freely by the steam trap, the gas will become soluble in the condensate when subcooling occurs. If oxygen is present, the corrosion rate Is accelerated. 

When carbon dioxide is present, only those traps that discharge condensate and noncondensable gases at or near saturation temperature (within 3°C) should be used. The introduction of new traps that claim to save energy by deliberately subcooling condensate has led to several problems. The new traps do not remove carbon dioxide and corrosion results. Steam leaks develop at threads, uhions, and welds. 

The corrosion products (copper and iron carbonates) are soluble in the low pH system. When pressure drops across the small orifice, the corrosion products are redeposited as a solid. Plugged trap discharges quickly occur as a result, or solids cause trap malfunction. 

Plants using makeup water that contains carbonates or bicarbonates can expect low-pH carbonic acid to cause difficulty in all portions of the steam systems if precautions are not taken. Possible precautions include  

Proper observance of these precautions can minimize carbon dioxide effects with resulting energy savings and reduced maintenance costs for steam systems. 

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Table 8.6 Effect of carbon dioxide exposure on breathing rates...

Fig. B.5. Effect of carbon dioxide lax on electricity price for a combined cycle gas turbine plant.

Figure 4-463. Effect of carbon dioxide concentration on corrosion rate. (From Ref. [211J.)...

Carbon dioxide and calcium carbonate The effect of carbon dioxide is closely linked with the bicarbonate content. Normal carbonates are rarely found in natural waters but sodium bicarbonate is found in some underground supplies. Calcium bicarbonate is the most important, but magnesium bicarbonate may be present in smaller quantities in general, it may be regarded as having properties similar to those of the calcium compound except that on decomposition by heat it deposits magnesium hydroxide whereas calcium bicarbonate precipitates the carbonate. 

It is necessary to draw attention to the variable pH of water which may be encountered in quantitative analysis. Water in equilibrium with the normal atmosphere which contains 0.03 per cent by volume of carbon dioxide has a pH of about 5.7 very carefully prepared conductivity water has a pH close to 7 water saturated with carbon dioxide under a pressure of one atmosphere has a pH of about 3.7 at 25 °C. The analyst may therefore be dealing, according to the conditions that prevail in the laboratory, with water having a pH between the two extremes pH 3.7 and pH 7. Hence for indicators which show their alkaline colours at pH values above 4.5, the effect of carbon dioxide introduced during a titration, either from the atmosphere or from the titrating solutions, must be seriously considered. This subject is discussed again later (Section 10.12). 

In steam-condensate systems, we are primarily concerned with the effect of carbon dioxide on pH levels. For example (and assuming all carbon dioxide is fully hydrated to carbonic acid) ... 

Carbon Balance in Northern Ecosystems and the Potential Effect of Carbon Dioxide Induced Climate Change Miller, P. C., Ed. CONF-8003118. National Technical Information Service Springfield, VA, 1981. 

Hotchkiss, J. H., Chen, J. H., and Lawless, H. T. (1999). Combined effects of carbon dioxide addition and barrier films on microbial and sensory changes in pasteurized milk. J. Dairy Sci. 82, 690-695. 

Burch, R. and Urbano, F.J. (1995) Methane combustion over palladium catalysts The effect of carbon dioxide and water on the activity, Appl. Catal. A 123, 173. 

Describe the effects of carbon dioxide, pH, temperature, 2,3-bispho-sphoglycerate, anemia, and carbon monoxide poisoning on the transport of oxygen... 

Also, by the very nature of chemical transformations, there are almost always unused chemicals remaining. These chemical leftovers include contaminants in the raw materials, incompletely converted raw materials, unavoidable coproducts, unselective reaction by-products, spent catalysts, and solvents. There have long been efforts to minimize the production of such waste products, and to recover and reuse those that cannot be eliminated. For those that cannot be reused, some different use has been sought, and as a last resort, efforts have been made to safely dispose of whatever remains. The same efforts apply to any leftovers from the production of the energy from the fuels produced or consumed by the processing industries. Of particular immediate and increasing concern are the potential detrimental effects of carbon dioxide emissions to the atmosphere from fossil fuel combustion, as discussed further in Chapters 9 and 10. 

In the absence of carbon dioxide, only 1,3,7-octatriene (16) was formed. The effect of carbon dioxide is not clear. One explanation is via the... 

There appeared several reports treating the activating effect of carbon dioxide on the dimerization or telomerization of butadiene, as described before. But in none of these reactions did carbon dioxide behave as a reactant. Sasaki, Inoue, and Hashimoto found that carbon dioxide was incorporated to a small extent into the dimer of butadiene (103). 

The chemistry of carbon, and radiocarbon, in the atmosphere represents one of the most important areas of environmental research today. The primary practical reason for this is the increasing attention which must be paid to the critical balance between energy and the environment, especially from the viewpoint of man s perturbations of natural processes and his need to maintain control. Probably more than other species, carbonaceous molecules play a central role in this balance. Some of the deleterious effects of carbonaceous gases and particles in the atmosphere are set down in Table 3. The potential effects of increased local or global concentrations of these species on health and climate have led to renewed interest in the carbon cycle and the "C02 Problem". It should be evident from the table, however, that carbon dioxide is not the only problem. In fact, the so-called "trace gases and particles" in the atmosphere present an important challenge to our interpretation of the climatic effects of carbon dioxide, itself [20]. 

The chemical effects of carbon dioxide breakthrough can be clearly seen on the right hand side of each of the figures. There is a strong directional trend reported in the reservoir, which is reflected in the geochemical signal. The producing wells which lie on trend with the C02 injectors show a rapid chemical response in contrast to the off trend wells for which the response is considerably delayed. 

Other early workers in this field include Briggs and Sinha 61), who measured the effect of carbon dioxide on coal and McBain et al. 6 ), who adsorbed water, heptane, and benzene on sugar charcoal. 

Cullen DJ, Eger El Cardiovascular effects of carbon dioxide in man. Anesthesiology 41 345-349, 1974... 

Woods SW, Charney DS, Goodman WK, Heninger GR (1988a) Carbon dioxide-induced anxiety behavioral, physiologic, and biochemical effects of carbon dioxide in patients with panic disorders and healthy subjects. Arch Gen Psychiatry 45 43-52 Woods SW, Kosten K, Krystal JH (1988b) Yohimbine alters regional cerebral blood flow in panic disorder [letter]. Lancet 2 678... 

Collins, W. B. (1976). Effect of carbon dioxide enrichment on growth of the potato plant. HortScL, 11, 467 69. 

Figure 6. Mechanistic pathway for the proposed enhancing effect of carbon dioxide in the alkylation of acetonitrile over the active basic sites...

Ignition Parameters B.N. Kondrikov et al, Ignition and Gasification of Ballistite Powder Under the Effect of Carbon Dioxide Laser Radiation , TrMoskKhimTekhnolInst 83, 67—78 (1974) (Russ) CA 85, 162865 (1976) [Reported is the effect of C02—laser radiation... 

Yermilov V, Rubio J, Ohshima H (1995) Formation of 8-nitroguanine in DNA treated with peroxyni-trite in vitro and its rapid removal from DNA by depurination. FEBS Lett 376 207-210 Yermilov V, Yoshie Y, Rubio J, Oshima H (1996) Effects of carbon dioxide/bicarbonate on induction of DNA single-strand breaks and formation of 8-nitroguanine, 8-oxoguanine and base-propenal mediated by peroxynitrite. FEBS Lett 399 67-70... 

Bacastrow R.B. and Keeling C.D. (1979) Models to predict future atmospheric CO2 concentrations. In Workshop on the Global Effects of Carbon Dioxide from Fossil Fuels U.S. Dept. Energy Conf. -770385, NTIS, Springfield, VA, 72-90. 

The possibilities of amino acid thioesters in peptide synthesis have been demonstrated very early as well as the effect of carbon dioxide supporting the involvement of N-carboxyanhydrides in the hydrolysis and polymerization pathways [127,176,177]. Aminothioacids can also be converted into NCAs [152,178,179] but they can, in addition, be activated by oxidation into disulfides which are much more reactive [151]. 

Denny, F.E., Thornton, N.C., and Schroeder, E.M., The effect of carbon dioxide upon the changes in the sugar content of certain vegetables in cold storage, Cont. Boyce Thompson Inst., 13, 295-311, 1944. 

Fig. 30.—Effect of carbon dioxide in reducing the quantum yield < N2°6 (corrected for screening by nitrogen tetroxide) A—4,050, O—3660, 0-3,130 A.

Klier K, et al. Catalytic synthesis of methanol from CO/H2 IV. The effect of carbon dioxide. J Catal. 1981 74 343-60. 

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