Carbon monoxide concentration

The carbon monoxide concentration of gas streams is a function of many parameters. In general, increased carbon monoxide concentration is found with an increase in the carbon-to-hydrogen ratio in the feed hydrocarbon a decrease in the steam-to-feed-carbon ratio increase in the synthesis gas exit temperature and avoidance of reequiUbration of the gas stream at a temperature lower than the synthesis temperature. Specific improvement in carbon monoxide production by steam reformers is made by recycling by-product carbon dioxide to the process feed inlet of the reformer (83,84). This increases the relative carbon-to-hydrogen ratio of the feed and raises the equiUbrium carbon monoxide concentration of the effluent. 

Fig. 4-2. Typical central city diurnal variation in carbon monoxide concentration, in a city in the United States. Spring (------), summer (------), fall (..), winter (----).

Carbon monoxide is a colourless, odourless gas and - without chemical analysis - its presence is undetectable. It is produced by steam reforming or incomplete combustion of carbonaceous fuels typical carbon monoxide concentrations in common gases are given in Table 5.30. 

Table 5.30 Typical carbon monoxide concentrations in gases...

Applicability of Semiconductor Gas Sensors Research into the applications of this type of sensor has mainly been concerned with measuring carbon monoxide concentration in flue gases. Tests show that sensors follow the concentration of carbon monoxide in the flue gas. Improvement in sensor performance has resulted with the introduction of a catalytic additive (palladium or... 

CALINE3 (California Line Source Model) is a line source dispersion model tliat can be used to predict carbon monoxide concentrations near liighways and arterial streets given traffic emissions, site geometry, and meteorology. 

Many reformulated gasolines use oxygenated compounds as additives. Clean Air regulations specify the need for oxygenated fuel in 39 metropolitan areas with high carbon monoxide concentrations. The regulations for oxygenated fuel are seasonal ... 

The carbon monoxide concentration contours for 50 atm and 700 °K (Figure 9) indicate that the equilibrium CO leakage will not be high if equilibrium is reached when the initial composition is near the stoichiometric line. 

In all tests, the temperature in the first- and second-stage reactors was kept within the necessary temperature limits of 288°-482°C. Because the carbon monoxide concentration was low in many of the tests, the second stage was not used to full capacity as is indicated by the temperature rise in runs 23, 24, and 27. The temperature profile shows the characteristic rise to a steady value. With the space velocities used (<5000 ft3/ft3 hr), the temperature profile is fully developed in the first stage within 30.0 in. of the top of the catalyst bed. A characteristic dip in temperature was observed over the first 8-10 in. of the catalyst bed in all runs. This temperature profile may indicate the presence of deactivated catalyst in this region, but, until the catalyst can be removed for examination, the cause of the temperature drop cannot be determined. There is no evidence that this low temperature zone is becoming progressively deeper. It is possible that an unrecorded brief upset in the purification system may have poisoned some of the top catalyst layers. 

Thermal inversions make winter the most unfavorable season for clean air. Vast differences in air quality are found in the industrialized north, and the residential southwest regions. Particulate matter influences mainly the north, where industries, landfills, and the dried bed of Texcoco Lake are located. Sulfur oxides impinge primarily on the northeast and southwest. High carbon monoxide concentrations are found in heavy traffic areas such as the northwest. Ozone affects predominantly the southwest at any season. We have selected air quality records from data generated by stations registering the higher pollutant levels, as follows ... 

The Pd-Sn/C catalysts (1 to 7.5% Pd containing 0 to 1% Sn) were heated under vacuum at 150°C and then exposed to hydrogen. These preactivated samples were then titrated with carbon monoxide, a veiy specific ligand for Pd, up to 800 Torr at 30°C. A general linear trend of carbon monoxide concentration with % Pd in Figure 15.3 indicates that the carbon monoxide adsorption is directly correlated to Pd concentration, as expected. The trend is independent of Sn content. This linear Pd-CO trend indicates that the particle size distribution is similar for the different catalysts. However, Figure 15.3 also indicates no relationship between % H2S irreversibly adsorbed and % Pd. 

It has already been stated that the principal toxicant in a fire scenario is carbon monoxide, generated when all carbonaceous materials burn. Moreover, the carbon monoxide concentration in full scale fire scenarios depends heavily on fire load (i.e. how much material is burning, per unit volume) and on geometrical arrangements, including ventilation, while the dependence on materials is of a lower order. 

Multi-sensor fire detectors provide faster detection with fewer false alarms. These sensors are capable of monitoring the environment for multiple purposes, e.g. carbon monoxide concentration, concentration of flammable gases and indoor air quality, too. 

Sell, J. A. Herz, R. K. Monroe, D. R. "Dynamic Measurement of Carbon Monoxide Concentrations in Automotive Exhaust Using Infrared Diode Laser Spectroscopy" SAE Paper No. 800463, 1980. 

Ca2 is given by the equilibrium A2/A1, with the equilibrium constant K 2ai = Ca2/(Cai Cco). Substituting the carbon monoxide concentration by the partial pressure and applying Eq. 1 yields... 

Reaction 2-6 is sufficiently fast to be important in the atmosphere. For a carbon monoxide concentration of 5 ppm, the average lifetime of a hydroxyl radical is about 0.01 s (see Reaction 2-6 other reactions may decrease the lifetime even further). Reaction 2-7 is a three-body recombination and is known to be fast at atmospheric pressures. The rate constant for Reaction 2-8 is not well established, although several experimental studies support its occurrence. On the basis of the most recently reported value for the rate constant of Reaction 2-8, which is an indirect determination, the average lifetime of a hydroperoxy radical is about 2 s for a nitric oxide concentration of 0.05 ppm. Reaction 2-8 is the pivotal reaction for this cycle, and it deserves more direct experimental study. 

Sklarew et al. evaluated their particle-in-cell A -theory approach for atmospheric diffusion of carbon monoxide and for photochemical smog. All-day averages of carbon monoxide concentration were predicted to be within 20% of the measured averages at 12 monitoring stations, and the correlation coefficient of measured with observed concentrations was 0.73. 

TABLE 5-4 Statistical Comparison of Model Calculations and Observations of Carbon Monoxide Concentration"... 

Carboxyhemoglobin Concentration [HbCO] This can be estimated with the method of Jones and co workers. The subject holds a deep breath for 20 s to allow equilibration of carbon monoxide between alveolar air and blood and then expires a sample of that air into a container. The air carbon monoxide concentration may be directly related to carboxyhemoglobin concentration [HbCO]. The test can be performed before exposure in an environmental chamber to help to verify that the subject has not received inordinate ambient pollutant exposure. 

Jones, R. H., M. F. Ellicott, J. B. Cadigan, and E. A. Gaensler. The relationship between alveolar and blood carbon monoxide concentrations during breathholding. Simple estimation of COHb saturation. J. Lab. Qin. Med. 51 553-564, 1958. 

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