Showing papers on "Countercurrent exchange published in 1976"

Single mixed refrigerant, closed loop process for liquefying natural gas

Abstract: A fluid material is cooled through a temperature range exceeding 200° F. by heat exchange with a single mixed refrigerant composition in a heat exchange zone forming a part of a closed loop refrigeration cycle thus assuring high reliability and low investment by virtue of simplification of the equipment required and ease of control thereof. The process is especially useful for liquefaction of natural gas. Refrigerant in the refrigeration loop containing constituents having increasingly lower boiling points is successively directed from a compression zone to a condensation zone, thence to a heat exchange zone, next expanded in an expansion zone, returned to the heat exchange zone for countercurrent flow against the refrigerant flowing therethrough from the condensation zone to the expansion zone, and finally returned to the compression zone. The natural gas is directed to the heat exchange zone and liquefied therein by countercurrent flow against the cold refrigerant stream flowing from the expansion zone to the compression zone. The refrigerant is made up of C 1 to C 5 hydrocarbons plus nitrogen as an optional constituent with the relative proportions of the constituents being controlled so that the combined cooling curve of the hot refrigerant stream and the feed gas closely matches the heating curve of the cold refrigerant stream in a sense that the curves are in close proximity at the lowest temperature levels thereof and relatively uniformly and slowly diverge as the highest temperature points on the curves are approached.

Method for indirect evaporative cooling of upflowing fluid by contact with downflowing water from overlying evaporative cooling section

Abstract: A high efficiency, induced draft, combination counterflow-crossflow fluid cooling apparatus and method is provided which gives unexpectedly enhanced cooling of hot fluid by causing the fluid to pass upwardly through a series of serpentine heat exchange conduits in primarily countercurrent, indirect sensible heat exchange relationship with external cooling water gravitating from an overlying evaporative water cooling section. Crossflowing air currents are pulled through the apparatus to evaporatively cool the water not only in the upper cooling section but also in the sensible heat exchange area as well. Countercurrent flow of coolant water and fluid to be collected ensures that the coldest water and coldest fluid are in thermal interchange during the final stages of fluid cooling at the upper ends of the heat exchange conduits, so that the fluid temperature can approach that of the cold water as opposed to approaching the temperature of heated water found adjacent the lower ends of the conduits, which is conventional in cocurrent fluid units of this type. The fluid conduit system is preferably arranged for causing increased fluid residence time, and thereby greatest temperature difference and longer heat exchange between the fluid and coolant water adjacent the air inlet of the apparatus where air and coolant water temperatures are lowest relative to the fluid to be cooled, so that an ideal countercurrent flow relationship is obtained and maximum heat transfer is assured. An underlying water collection basin is also employed in the apparatus which is constructed to permit collection of cooling water to a level above that of the lowermost portions of the hot fluid conduits, in order to allow the hot fluid traveling through the conduits to heat the collected water to prevent freezing thereof during wintertime operations when the internal water pump is shut down causing the stoppage of all evaporative cooling and hence a raising of the lower water basin level.

Ion exchange method

Abstract: The invention is concerned with an ion exchange treating system wherein two or more exchanger or absorber vessels are connected in series, each vessel being filled with ion exchange resin leaving sufficient freeboard to allow for expansion of the medium. Each vessel is provided with an expansion chamber positioned above it and includes a conventional distribution system. The flow of liquids passing through the system is countercurrent with respect to the medium to be treated and the medium which regenerates the ion exchanger or absorber. Generally, the liquid to be treated enters the first vessel at the bottom, exiting from the top, entering the second vessel at the top and exiting therefrom at the bottom.

The steady and unsteady state analysis of a simple gas centrifuge

Abstract: The operating theory of the gas centrifuge is developed under both steady and unsteady state behavior. It is shown that countercurrent flow patterns in a gas centrifuge enhance the possible separation. The effect of self-diffusion of the gaseous mixtures is shown to be significant with low molecular weight gases but of less significance with heavy gases such as uranium isotopes. The time required to develop steady state pressure and concentration profiles is in the order of minutes, even with no net flow to and from the machine.

Dynamic Analysis of a Plate Heat Exchanger System

Abstract: This paper presents a systematic analysis of static and dynamic characteristics of plate heat exchangers having a number of heat transfer plates. There are various flow types in a plate heat exchanger system. The results are numerically compared under the condition that each flow rate of the hot- and cold-side fluids remains constant, respectively in any flow type. The significant results are : 1) In almost every flow type, the temperature effectiveness increases as the number of passages increases. 2) Dynamic responses may greatly depend on the relation between the inlet and outlet passages where each fluid flows in a counter- or a parallel current. 3) Series flow types where the inlet and outlet passage are adjacent and the flow is a countercurrent have the best statics and dynamics among all types when the number of passages is the same.

Solid-fluid contacting process

Abstract: In a fixed-bed solid-fluid contacting process, wherein adsorption and regeneration are performed in countercurrent flow, a portion of contaminated solid particles in the bed is extracted from the bed for washing, simultaneously when a fluid is treated by passing through the bed. The solid particles extracted are washed and recycled to the bed at the time of other operations, for example, regeneration step. The process is improved in the time cycle of treatment which is shortened and the pressure loss which is decreased. The process is also free from disturbance of bed and excellent in treatment efficiency. A simple and compact apparatus is available for the process. Typical example of application is ion exchange reaction.

One-Dimensional Convective and Conductive Geothermal Heat Flow

Abstract: A number of research workers have investigated two- and three-dimensional natural convective heat flow in porous media containing a single-phase fluid. Results indicate that convective heat flow in geothermal reservoirs can be high with low geothermal gradients within the convection cells. Single-phase convection can occur only in two or three dimensions; however, it is evident that steam and hot water sometimes exist simultaneously in geothermal areas. The large difference in density between steam and hot water provides a driving force that tends to segregate the two phases, making countercurrent vertical one-dimensional fluid flow theoretically possible. This paper presents the results of a study of one-dimensional, vertical, two phase, steady-state, geothermal fluid and heat flow. The object of the investigation was to understand the one-dimensional convective heat flow that may occur where conditions have been stable long enough for the flow to approach steady-state. Results presented herein apply to unfractured porous media. Similar results should apply to fractured reservoirs and permeable fault zones. 3 refs., 8 figs.

Frictional pressure drop for turbulent gas streams in wetted-wall columns with cocurrent and countercurrent gas-liquid flow

Abstract: The flow behavior of the laminar liquid film and the turbulent gas stream flowing cocurrently or countercurrently in a wetted-wall column was studied theoretically and experimentally. Analytical solutions were obtained for the velocity profiles of gas and liquid and the frictional pressure drop for the gas stream. Frictional pressure drops for the gas stream were measured for the air-water system and the air-glycerol solution system. Experimental results were in good agreement with the theoretical predictions.

Removal of trace copper ions from water

Abstract: Cations, such as copper, are recovered from very dilute aqueous solutions by means of a bubble fractionation process comprising countercurrent contacting of the feed solution with a stream of gas bubbles and a surfactant in an elongated vertical column.

Countercurrent flow reaction chamber for plural stages of HF alkylation

Abstract: An alkylatable reactant is alkylated with an olefin-acting reactant, utilizing a fluid HF catalyst in a countercurrent flow reaction chamber wherein reactants are flowing upward and the fluid catalyst is flowing downward. The fluid catalyst enters the reaction chamber at the top and is withdrawn at the bottom. Reaction chamber effluent passes into a settling chamber wherein it is separated into a catalyst phase and a hydrocarbon phase, the latter passing through a second reaction chamber in which it contacts a countercurrent flow of higher concentration fluid HF catalyst, and into a final settling chamber, wherein a hydrocarbon reaction product phase is separated from a catalyst phase and withdrawn. Also disclosed is a novel unitary alkylation vessel comprising, in combination, a countercurrent reaction chamber, a settling chamber, a second reaction chamber, and a final settling chamber.

Catalytic reactor employing moving belt of catalyst - with or without external heat exchange, for reaction of gaseous cpds.

Abstract: The reactor includes a continuous metal belt driven by motor. the belt comprises a series of boxes, each of which has its two largest sides made of metal mesh and is filled with catalyst pellets. Gases are directed through the boxes and then recovered. Heat exchange, to maintain the reaction temp. constant, takes place between the belt and a heat exchange fluid at a part of the belt distinct from that traversed by the gas. Pref. the heat exchange fluid consists of the gas which has been removed from the reactor and returned to the belt in countercurrent after passage through a heat exchanger. The boxes may contain metallic heat exchange bodies. Reactor heat exchange system is simplified. Catalyst can be regenerated without shutdown.

Bake-oven with closed ring steam heating tubes - having counter current flow of combustion gases and the water in the tubes

Abstract: In a bake oven having >=1 baking chambers with heating by closed ring-type tubes partly filled with water, the lowest part of each ring being inclined to the horizontal, the hot gases from a gas or oil burner flow in countercurrent to the water in the tubes and, after heating the tubes, pref. pass into a space in which >=1 steam generator is installed. The use of countercurrent flow is thermally more efficient and the useful heat prodn. is greater, while more uniform heat loading of the tubes is achieved. The use of masonry is superfluous and the heat capacity, and therefore heating up time of the oven, is reduced.

Evidence of a Westward-Flowing "subarctic Countercurrent" in the North

Abstract: An examination of surface current velocity data obtained from two independent ship sources suggests the presence of a narrow, weak, westward-flowing countercurrent at a latitude of approximately 50'N in the subarctic Pacific region. Oceanographic survey data collected in the region from the summers of 1958 and 1959 also indicate such a countercurrent extending zonally for more than 1000 km. The countercurrent can be explained bv consideration ofthe wind-stress vorticity field over the region.