Ammonia Air Research Articles

Corrosion and Corrosion Crack Resistance of the PT3V Titanium Alloy in Aqueous Solutions of Ammonia

We describe some results of experimental investigations into the influence of the structure of the PT3V titanium pseudo-α-alloy, formed by plastic deformation and heat treatment, on its mechanical properties, corrosion, and cyclic crack resistance in aqueous ammonia media of various concentrations and temperatures. The kinetics of electrode processes on a smooth surface and at the tip of a fatigue crack is studied. By using the methods of the dropping mercury electrode and a disk rotating electrode, we identified the main partial electrochemical reactions and determined the limiting stage of the cathodic process (diffusion of molecular oxygen), the hydrodynamic conditions of the course of these reactions, and the diffusivity of oxygen in aqueous ammonia media at 298 K (D = 4.8·10−8m2/sec). The kinetics of fatigue and corrosion-fatigue fracture of the alloy under study (crack initiation and growth) was investigated as well. We have established that, at the stage till crack initiation in air, alloys with a globular structure have the maximum lifetime, which is 1.5–2 times as much as that of lamellar structures. In corrosive media, the time to crack initiation increases with the ammonia concentration and solution temperature. A corrosive medium strongly affects fatigue crack growth in the alloy for ΔK below 5–7 MPa m1/2, i.e., if V > (2·10−8–8·10−9) m/cycle, especially for the initial (thin-lamellar) and β-transformed structures. With the help of investigations of electrochemical processes in a corrosion-fatigue crack, we established the linear dependence of the stabilized value of the electrolytic potential Est on ΔK. Specific features of the fatigue fracture of alloys having different structures in air and aqueous ammonia media were discovered on the basis of metallographic analysis. Finally, we analyzed the kinetics and the mechanisms of corrosion and corrosion-fatigue crack growth.

Flammability limits, ignition energy, and flame speeds in H 2–CH 4–NH 3–N 2O–O 2–N 2 mixtures

Experiments on flammability limits, ignition energies, and flame speeds were carried out in a 11.25- and a 400-liter combustion vessel at initial pressures and temperatures of 100 kPa and 295 K, respectively. Flammability maps of hydrogen–nitrous oxide–nitrogen, methane–nitrous oxide–nitrogen, ammonia–nitrous oxide–nitrogen, and ammonia–nitrous oxide–air, as well as lean flammability limits of various hydrogen–methane–ammonia–nitrous oxide–oxygen–nitrogen mixtures were determined. Ignition energy bounds of methane–nitrous oxide, ammonia–nitrous oxide, and ammonia–nitrous oxide–nitrogen mixtures have been determined and the influence of small amounts of oxygen on the flammability of methane–nitrous oxide–nitrogen mixtures has been investigated. Flame speeds have been measured and laminar burning velocities have been determined for ammonia–air–nitrous oxide and various hydrogen–methane–ammonia–nitrous oxide–oxygen–nitrogen mixtures. Lower and upper flammability limits (mixing fan on, turbulent conditions) for ignition energies of 8 J are: H 2–N 2O: 4.5 ∼ 5.0% H 2(LFL), 76 ∼ 80% H 2(UFL); CH 4–N 2O: 2.5 ∼ 3.0% CH 4(LFL), 43 ∼ 50% CH 4(UFL); NH 3–N 2O: 5.0 ∼ 5.2% NH 3(LFL), 67.5 ∼ 68% NH 3(UFL). Inerting concentrations are: H 2–N 2O–N 2: 76% N 2; CH 4–N 2O–N 2: 70.5% N 2; NH 3–N 2O–N 2: 61% N 2; NH 3–N 2O–air: 85% air. Flammability limits of methane–nitrous oxide–nitrogen mixtures show no pronounced dependence on small amounts of oxygen (<5%). Generally speaking, flammable gases with large initial amounts of nitrous oxide or ammonia show a strong dependence of flammability limits on ignition energy.

Phase Transition of APP Form I to II and Synthesis of APP Form II from the System of Ammonium Orthophosphate-Urea

Phase transition of ammonium polyphosphate (APP) form I to II was examined and 100% transformation of form I to II was achieved by heating form I at 280 to 290 °C under alternate gas flow of wet ammonia and dry air. Direct preparation of APP form II was made by heating a mixture of ammonium hydrogenorthophosphate and urea under wet ammonia at 280 to 300°C for 3 to 4 h. By adding APP form II as a seed crystal, APP form II was prepared by heatng a mixture of ammonium hydrogenorthophosphate and urea under wet ammonia at 280 to 305 °C for 1 h.

Ammonia stripping from MSW landfill leachate in bubble reactors: process modeling and optimization

This work presents a study of the ammonia air stripping pro cess in a semi-flow batch bubble reactor as a pre-treatment for municipal solid waste (MSW) landfill leachate. In order to assess the optimum treatment conditions from a technical and an economic point of view, the research was carried out in the following steps: 1) experimentation in a pilot plant; 2) mathematical model development; and 3) economic analysis. The experimentation showed that it is possible to achieve high ammonia removal efficiencies even without basificant dosage, if temperature is maintained between approximately 60 and 70°C. The development and calibration of a mathe matical model permitted the study to determine the treat ment efficiency of the process under several operating condi tions. The economic analysis has shown that, with a removal efficiency of approximately 70%, it is convenient to work without basificant dosage and at a temperature of 70°C. These conditions can also be considered optimal from a tech mcal point of view.

Reliability analysis of protective systems for the ammonia—air mixing plant

Abstract The reliability of the protective system for an ammonia—air mixing unit of a nitric acid plant is analysed by evaluating the time profiles of the expected number of normal trips, spurious trips and destructive hazards. The method of Kumamoto et al . 1 is used for this purpose. Based on the contribution of important cut sets on the expected number of hazards, three different modifications of the flow sheet have been suggested to reduce the expected number of hazards.

The behavior of denser than air ammonia in the presence of obstacles—wind tunnel experiments

AbstractIn case of the release of pressurized liquid ammonia, a heavier than air gas cloud can be formed. It was found that the dispersion is very strongly influenced by the presence of obstacles.

Ambient concentrations of formaldehyde and ammonia in a screwworm fly rearing facility.

A facility for the mass rearing of sterilized screwworm flies used in fly eradication program efforts was described. Air concentrations of formaldehyde and ammonia were measured during industrial hygiene surveys conducted in the production plant which is currently the world's largest insect rearing facility. Formaldehyde, used as a bactericide and fungicide in the larvae media, was consistently found at levels below current and recommended TLVs. Ammonia, released as metabolic waste from the larvae, was occasionally found at elevated levels in some plant areas. Factors were identified which influenced the in-plant variations of ammonia air levels.

Ambient Concentrations of Formaldehyde and Ammonia in a Screwworm Fly Rearing Facility

A facility for the mass rearing of sterilized screwworm flies used in fly eradication program efforts was described. Air concentrations of formaldehyde and ammonia were measured during industrial hygiene surveys conducted in the production plant which is currently the world's largest insect rearing facility. Formaldehyde, used as a bactericide and fungicide in the larvae media, was consistently found at levels below current and recommended TLVs. Ammonia, released as metabolic waste from the larvae, was occasionally found at elevated levels in some plant areas. Factors were identified which influenced the in-plant variations of ammonia air levels.

Chemical and physical-parameters of liquid manure from swine confinement facilities: Health implications for workers, swine and the environment

Liquid manure from storage pits in twenty-three swine confinement operations was characterized by taking multiple measurements, over a 6-month period, of twelve different chemical and physical parameters. Low temperature, high ammonia content, excess hydrogen ion content (as measured by low bicarbonate alkalinity and excess Volatile Acids) and excess Volatile Solids were often inhibitory or toxic for anaerobic digestion in the pits. Relative to optimal anaerobic digestion, bacterial metabolic reaction rates are slow, production rates of methane and other gases are relatively low, odorous intermediate products (organic acids and sulfur-containing compounds) are relatively high and waste stabilization is relatively low. Conditions favoring the production of hydrogen sulfide, ammonia and other odorous and toxic compounds prevail over conditions favoring methane production. These characteristics were accentuated in grower and finishing buildings as compared with farrowing buildings. High sulfate concentrations in water sources are potentially hazardous because they increase the sulfide content of the manure and therefore increase the potential exposure of workers and swine to toxic levels of hydrogen sulfide. Only a portion of the NH 3 present in the air of confinement buildings comes from the manure pit. Therefore, eliminating the pit under the building would not eliminate the air ammonia problem. Manure in farrowing buildings could possibly be treated in the pit to enhance stabilization by controlling temperature, water content and loading rates. However, in-the-pit treatment to enhance anaerobic digestion in nursery, grower and finishing buildings may be more difficult because of the extremely adverse biological conditions in these pits.

Releases of anhydrous ammonia from pressurized containers — the importance of denser-than-air mixtures

The purpose of this paper is to examine the behaviour of ammonia vapour which has escaped to the atmosphere as a result of the accidental failure of a pressurized container. It is shown that the circumstances of the release are such that the formation of a cold ammonia air mixture, which is denser than the surrounding air, is likely. As a result, gravity driven phenomena must be taken into account; the cloud slumps and becomes very broad. It is shown that this slumping is insensitive to assumptions made about the rate of entrainment of the air and about the rate at which the mixture is heated by the ground. It is also demonstrated that, unless the windspeed is exceedingly low, the dispersing ammonia may not become buoyant; this is another phenomenon that is insensitive to parameter variations. A section of the paper is devoted to a critical examination of the uncertainties which must be overcome before a complete model of the escape of ammonia from a pressurized container can be written down. It is argued, however, that the characteristic features described above are not sensitive to these uncertainties. Finally, a simple model is used to describe the behaviour of a 20 Te “puff” of ammonia and the results are compared with accounts of accidental escapes of about that size. It is demonstrated that agreement with such facts as can be established is satisfactory.

The frequency response of a packed gas absorption column

A theoretical model is given for the unsteady-state behaviour of a packed gas absorption column and the theoretical frequency responses are derived. Experimental frequency responses obtained on a 4 in. i.d., 6ft. high laboratory absorption column operating with the system air—ammonia—water and on a 3ft. i.d., 15ft. high plant absorption column operating with the system inert gas—hydrogen chloride—water are presented.

Effect of Dust and Ammonia Air Contamination on Turkey Response

Turkeys were subjected to two levels of dust and ammonia air contamination in accordance with a 2 x 2 factorial design. Three trials, each of 12 weeks duration, were completed under controlled conditions similar to those found in commercial poultry housing. The incidence of airsacculitis at slaughter was found to be significantly affected by the dust air pollution. Increasing the dust contamination from the low level considered in this study to the high level caused more than double the rate of airsacculitis. No effect of ammonia on airsacculitis was detected. Also, interaction between dust and ammonia was not significant. Mortality rates and feed conversion of the turkeys were not affected by the dust and ammonia treatments. Birds exposed to the high dust and ammonia concentrations showed considerable loss of cilia from the epithelium lining the trachea.

Mass transfer in supported forths

AbstractOperating and mass transfer characteristics are reported for a supported froth apparatus consisting of a dual‐flow sieve plate column with eggcrate packing above the plate. The assembled packing produced a series of vertical tubes and served to support the froth generated at the plate, increasing its height and consequently the contact time. Addition of the packing improved the mass transfer efficiency. Systems studied were ammonia–air–water and carbon dioxide–air–water. Effects of liquid and gas rate as well as packing size and spacing are correlated. A model based on measurable physical parameters was developed to predict efficiency, and a generalized correlation of efficiency was developed.