Inlet Box Research Articles

Failure analysis of ammonium chloride salt coagulation corrosion of U-tube heat exchanger in diesel hydrogenation unit

Diesel hydrogenation unit is an important equipment for processing inferior oil in petroleum refining enterprises. Among them, the U-tube heat exchanger has been in high temperature and corrosive environment containing chlorine for a long time. Serious problem of tube bundle corrosion failure caused by ammonium chloride salt deposit. Anatomy of the diesel hydrogenation heat exchanger showed that the leakage part mainly appeared in the outermost bundle of the heat exchanger tube near the exit section, and the local area showed a large area of gully damage. Metallographic and XRD results show that the failure tube bundle material does not have manufacturing defects, and the corrosion location scale contains NH4Cl and iron oxides. The process flow analysis based on PR-NRTL model showed that the heat exchanger was in the NH4Cl crystallization temperature range, and the crystallization temperature increased with the increase of N and Cl contents in raw materials. Fluid simulation analysis of inlet tube box and single U-tube is carried out by using component transport equation and condensation model. Computational fluid dynamics (CFD) results indicate that there is a low velocity zone with high volume fraction of gas phase in the tube box. The higher gas volume fraction results in the formation of more NH4Cl particles into the U-tube bundle during heat transfer cooling. With the decrease of temperature, liquid water content in U-tube increases gradually and mainly distributes at both sides and bottom of tube bundle. The gas phase gradually fills the top of the tube bundle, and the oil and gas stratification becomes more obvious. The mass transfer rate and corrosion rate were the highest at the bottom and both sides of the tube bundle. With the temperature decreases, the NH4Cl particles generated in the tube continue to increase. The particles were deposited at 2000–3000 mm near the outlet section of the U-tube tube. NH4Cl particles absorbed liquid water, resulting in under-deposit corrosion of the tube bundle, and eventually led to the thinning and leakage of the heat exchanger tube bundle.

Effect of inlet duct design on fan performance and static pressure measurements of indoor air handling units (ASHRAE RP-1743)

Increasing energy efficiency requirements lead to substantial increases in residential air handler unit’s length, in turn preventing usage of requiring inlet ductwork for rating tests due to testing facilities space constraints. Therefore, the main goal of ASHRAE Research Project 1743 was to investigate reduced-length alternative inlet duct configurations as compared to ASHRAE Standard inlet duct in terms of fan performance. Additionally, the project investigated other effects that might affect the repeatability of equipment testing. The investigated effects were hysteresis effect associating with adjusting external static pressure through unit under test, atmospheric pressure effect associating with daily fluctuations of atmospheric pressure in a location, side flow effect from a destratification fan in the testing facility, and floor distance effect on ASHRAE Standard 37 inlet duct. The reduced-length alternative inlet duct configurations considered were 4-inch inlet duct, inlet box with and without guide vanes, and nonconventional reduced alternative inlet duct. The alternative inlet duct configurations maintained fan performance within ±5% for fan power and ±2.5% for air volumetric flowrate except for the inlet box without guide vanes. The reduction in length relative to the standard inlet duct was between 38% and 44% for the inlet box configuration up to 71% and 73% for the reduced alternative inlet duct configuration. The hysteresis effect was significant for the push-through electronically-commutated-motor fan unit and was noticeable for the pull-through constant-torque-motor fan unit at a low air flowrate. Atmospheric pressure affected only the electronically-commutated-motor fan units significantly. Side flow from external ‘destratification’-fans had a significant effect on the push-through units in some of the configurations. Floor distance had an insignificant effect on fan performance during testing the standard inlet duct.

Study on Dust Turbulence-Chemical Agglomeration for Electrostatic Precipitation Technology

Due to the turbulent mixing between agglomeration agent and dust, the number of collisions per unit time between particles and droplets increases with the particle size in the process of chemical agglomeration, and the agglomeration efficiency increases accordingly. Turbulent agglomeration can promote the agglomeration effect of subsequent chemical agglomeration by strengthening the collision between particles and agglomerant droplets. The author used chemical agglomeration and turbulent mixing to cooperate in order to improve the efficiency of dust removal. Turbulent mixing can promote chemical agglomeration from agglomeration effect and dust removal efficiency, which can greatly improve electric dust removal technologyTurbulent mixing is the most intense at the inlet box position, and the agglomeration effect is the best. Turbulent mixing synergistic effect has an effect on dust removal efficiency. Compared with the three curves, it can be seen that the dust removal efficiency increases rapidly with the increase of agglomeration concentration, the curve trend changes obviously. The dust removal efficiency can reach 98.36 % and it is the highest in the middle section when the wind speed is greater than 11.2m/s. Through the experiment, the turbulent mixing and chemical coagulation method has a good application prospect in the electrostatic precipitators.

The Effects of Inlet Box Aerodynamics on the Mechanical Performance of a Variable Pitch in Motion Fan

This paper describes research involving an in-service failure of a “variable pitch in motion” fan’s blade bearing. Variable pitch in motion fans rotate at a constant speed, with the changing blade angle varying the load. A pitch-change mechanism facilitates the change in blade angle. A blade bearing supports each blade enabling it to rotate. The author observed that as the fan aerodynamic stage loading progressively increased, so did the rate of blade-bearing wear. The reported research addressed two separate, but linked, needs. First, the ongoing need to increase fan pressure development capability required an increase in fan loading. This increase was within the context of an erosive operating regime which systematically reduced fan pressure development capability. The second need was to identify the root cause of blade-bearing failures. The author addressed the linked needs using a computational analysis, improving the rotor inflow aerodynamic characteristics through an analysis of the inlet box and design of inlet guide vanes to control flow nonuniformities at the fan inlet. The results of the improvement facilitated both an increase in fan-pressure-developing capability and identification of the root cause of the blade-bearing failures.

Effect of inlet box on performance of axial flow fans

Numerical investigations on 3D flow fields in an axial flow fan with and without an inlet box have been extensively conducted, focusing on the variation of fan performance caused by the internal flow fields and the velocity evenness at the exit of the inlet box. It is interesting to find that although the inlet box is well designed in accordance with basic design principles, there is a flow separation region in it. Furthermore, this flow separation and the resulting uneven velocity distribution at the exit lead to some decrease in the efficiency and an increase in the total pressure rise of the fan. This research shows that the inlet box needs further improvement and such a check on the flow fields is of value for the design of inlet boxes.

Air inlet box for truck intercoolers made from polyphenylene sulphide

Behr GmbH & Co. has selected polyphenylene sulphide (PPS) as the material for a relatively large underbonnet component that measures 940 mm in length but weighs only 2.8 kg. In this application of a high-temperature-resistant polymer from Ticona GmbH, this polymer is used to produce the air inlet box for the intercooler fitted to the TG-A heavy-duty truck from MAN Nutzfahrzeuge AG. The development aim pursued by Behr, an original equipment manufacturer of automotive air-conditioning and engine-cooling systems, was to design a suitable alternative to the cast aluminium parts traditionally used in this area. The new part not only had to be just as efficient as the previous part but also had to save weight and above all reduce the number of finishing steps required in order to reduce overall component costs.

Experimental investigation of the internal flow field of rotating impeller passage with inlet box

Using PDA and its measurement system, the flow fields at the different peripheral locations of rotating impeller passage of a diagonal fan with inlet box are measured. The results are compared with the flow field of the rotating impeller passage of the same fan without inlet box. The differences of the flow characteristics of the rotating passage at the different peripheral locations are revealed. The effects of the complex flow in the inlet box on the internal flow of the rotating impell passage are investigated.

Supercritical flow near an abrupt wall deflection

The supercritical flow near an abrupt wall deflection is investigated experimentally and by computer simulations. An extensive series of tests were conducted on a 500 mm wide flume with Froude number up to 8 and wall deflection angle up to 11.3°. A special inlet box was installed to provide smooth flow conditions at the flume entrance. By analyzing the experimental data, explicit expressions are derived for the height of the shock and the velocity ratio. Experimental results are presented in the form of universal plots of the shock surface and the two-dimensional velocity field. These may be utilized for engineering applications or for the verification of mathematical models. The flow field near a wall deflection was computed by using a two-dimensional flow model based on the numerical solution of steady, shallow-water equations by the MacCormack explicit finite-difference scheme. The computed and measured flow depths and flow velocities are compared and are found to be in satisfactory agreement where the...

Numerical calculation of the dynamic behavior of solid particles through the inlet box with complex geometry of a fluid machine

A finite element method is used to calculate the three-dimensional gas flow field in the inlet box of a large-size fluid machinery. The dynamic behaviors of solid particles through the inlet box are obtained numerically by the “one way coupling” method. The trajectories of different-sized particles and the distribution of particle positions on the outlet plane of inlet box are investigated.

Fan Casing Noise Radiation

This paper presents a method for assessing the extent of casing noise radiation of a centrifugal fan relative to the aeroacoustic sources associated with the inlet box of the fan. Central to the method is a boundary element program which is used to compute the acoustic pressures on the surfaces of the fan casing in terms of its surface vibration which in this case was measured experimentally. Data from an earlier experiment was used as the starting point for this study. Available data included sound pressure measurements near and away from the inlet box of the fan and vibration measurements over the casing of the fan. Noise from the outlet duct of the fan was purposely highly attenuated. Computations of sound pressure, intensity, and power indicated that, at the blade passing frequency (300 Hz), the aerodynamic sources generated near the entrance plane of the inlet box of the fan dominate the noise spectrum in the field. On the other hand, at the first subharmonic frequency of the blade tone (150 Hz), the sound power generated from the inlet box and fan casing are within 3 dB of each other. Thus, for effective noise control at this frequency, it would be necessary to include both noise sources in the overall treatment.

Centrifugal Fan Performance With Distorted Inflows

Efforts to quantify degradation of the performance of a centrifugal fan subjected to distorted inflows are presented. The study centered on examination of pressure rise, efficiency, and onset of stall for a backwardly-inclined, airfoil-bladed fan. Nonuniform flow patterns were generated in an adjustable countervane damper assembly installed upstream of the inlet box, and systematic families of performance curves were generated. Results of these tests show that significant degradation in efficiency and pressure rise—as much as 10 to 15 percent—may result from moderately to severely distorted inflow patterns. Onset of stall was significantly influenced by severely distorted inflows.

A Study on the Effect iveness of the Elimination of Bacteria by an A-Type Air Purifier

In view of the intramural infection at the hospitals and clinics and the bactrial pollution of foods and pharmaceuticals in recent years, much attetion has come to be paid to the elimination of bacteria from the air inside the rooms.For this reason, there are commercially available many types of air purifiers, but not all the purifiers which can be placed inside the room are effective in eliminating air-borne bacteria.In the present study, the authors concerned themselves with bacterial elimination by means of an A-Type air purifier.For our experimental purposes, an inlet box (B) of 1.11m3 in content and another box (C) of 0.87m3 were respectively attached to the inlet and outlet sides of this A-Type air purifier. A nebulizer made of glass, which was capable of spraying the fine 0.3 p particles was installed in front of the box (B) and, by means of this nebulizer a bacterial strain, Serratia marcescens, per 182×106/ml, which was cultivated in a trypto-soy broth (in which 30g was dissolved in heated. water and sterilized to make 2, 000ml), was sprayed inside the box (B) and by activating the A-Type air purifier the bacteria were caught at two places, i. e., i) the suction inlet of the box (B) and ii) the outlet of the box (C) by use of an SY pinhole sampler.For measurement purposes, three different wind velocities of 8.7m3/min (main switch I), 9.1m3/min (main switch II) and 9.9m3/min (main switch III) were used. Moreove, the filter, special filter, activated carbon and sterilized bacterial container, which were the components of the furifier, were taken apart separately and each of them was subjected to careful examinations to measure the effect of bacterial elimination on these parts.As a result of the present study, the authors arrived at the following conclusions:1. In an experimental study with the use of Serratia marcescens, the amount of bacterial elimination by an A-Type air purifier was about 92%.2. Of various the components of the air purifier studied, the electrical dust collector had the highest effectiveness, 86.7%, followed in order by the filter with 45.7% and the sterilizing lamp with 18.7%.3. Since the effect of the sterilizing lamp was more or less similar to the 17.6% effectiveness when all the other inside components were removed, the effect of the sterilizing lamp alone was far from adequate.4. The filter installed in the present air purifier was 45% effective in eliminating bacteria.It is necessary after removing the bacteria from the air, to give due consideration to the disinfection of the bacteria still remaing inside the purifier.

A PORTABLE FORCED AIR PLANT DRYER

The need for a portable electric plant dryer for use by traveling botanists was brought up by Dr. Delzie Demaree during a discussion with my father, Everett Jenne, and me, two years ago. Dr. Demaree remarked that bulky conventional convection plant dryers tend to overload the light electrical circuits found in most American motels, and that dryers using gasoline or kerosene heat sources are hazardous. These comments led to the design of a small, efficient portable plant dryer by my father, who built several working models for Dr. Demaree, Dr. Robert Kral, and me. During a year's field trial in the United States and Mexico it was found that this 10 lb. dryer will, under normal conditions, dry two fully loaded 35 standard presses overnight. The Jenne Plant Dryer consists of a 660-watt heating element mounted at the inlet of a motor-driven blower unit. (Fig. l.a.). This blower forces the heated air into a flexible heavy gauge vinyl plastic hood which directs the air through the enclosed plant press or presses (Fig. l.b.). The sheet steel inlet box for the blower supports the motor-driven blower unit and encloses a 660 watt heating element. The open end of the inlet box is covered by a hard-ware cloth screen to prevent flammable material from being brought into contact with the hot heating element, which produces a rise of about 35? F above the ambient temperature. If it is desirable to reduce the drying rate or the amount of current required, a 300-watt or smaller light bulb can be substituted for the 660-watt heating element. The base also houses two 15-ampere DPST toggle switches under the blower unit and encloses the 16-gauge wiring (Fig. 2). The 100 cfm blower has a 2-l/s X 4-1/32 (outside dimensions) discharge flange and 3-1/8 diameter inlet opening. The 3 13/16 x 1 /8 wide fan wheel has forward curved blades and is attached to the motor shaft extension. The 115 volt, 60 cycle, 1/45 hp, shaded pole, single phase motor runs at 2870 rpm under full load (free air) conditions. The motor is rubber mounted on the side of the fan housing. A supply of 110-volt alternating current is required to operate this dryer. The current used with the 660-watt heating element is about 6.75 amperes. The heavy gauge vinyl plastic hood fastens to the discharge flange of the blower unit. It is made up of three short connecting and expanding sections and a straight section 3' long, 19 wide and 35 high. When two presses are to be dried, the zipper in the straight section is opened and the presses are set in place; the zipper is then closed and approximately one foot of the hood is tucked inside itself around the last press (Fig. l.d.). Air pressure inside the folded-in portion of the hood helps to seal the area around the sides of the last press. Webbing straps are fastened around the enclosed presses, limiting the amount of air by-passing them. (Fig. l.c, d.). If only one press is to be dried, half of the straight section of the hood is folded back inside and the press is inserted and strapped in place. It is hoped that this portable dryer, or modifications of it, will be of use to botanists throughout the world.

Influence of Bends in Inlet Ducts on the Performance of Induced-Draft Fans

Abstract This paper shows the great loss in capacity and efficiency of a fan that results from the location of elbows or bends close to the inlet boxes. The loss is shown to be a function of the type of bend, of its “aspect ratio” or ratio of depth to width, and of the direction in which the air is turned in the bend. By the use of guide vanes in the bend the loss can be almost entirely prevented. When scroll inlet boxes provided with guide vanes are used, this loss does not occur, but the capacity with such boxes is low, although the efficiency is maintained. The cause of the loss is not the friction in the bend, but is the poor distribution of the air leaving the bend and entering the inlet box. The use of a short length of straight duct between the bend and the inlet box will reduce the loss appreciably. Measurements by pitot tube of the distribution of velocity and static pressures at the entrance to the inlet boxes will indicate the existence of this loss and the desirability of inserting guide vanes in the bends.

Influence of Inlet Boxes on the Performance of Induced-Draft Fans

Abstract This paper presents experimental results of tests to ascertain the effect of inlet boxes on the performance of induced-draft fans. The tests showed the magnitude of the changes in performance that can be expected and emphasizes the need for testing fans with their inlet boxes attached. The conclusion drawn from the tests is that it is not sufficient for the fan user to know the characteristics of a selected fan with free inlet, but he also should know the characteristics when the inlet box is attached.