A METHOD TO CONSTRUCT A COUNTER FLOW PROCESS

Abstract: The invention describes a counter flow process, where an efficient contact is received between a solid, granular material (5) and a liquid or gas. The solid material is fed continually from above, forming a slide cone and is then moved downward through a set of concentric funnels (15) which create an even flow velocity of the granular material (5) over the cross section of the bed (1).

Description: TITLE: fi method to construct α counter flow process. BRIEF DESCRIPTION: The present invent ion concerns α method to get an efficient contact between a solid material in the form of grains and a l iquid or a gas. The process is performed in a closed vessel. The solid material is fed continuall from the top whereby a slide cone up- per surface is formed and the material continues to move downwards in a uniform motion. Simultaneously, a liquid or a gas passes up¬ wards in an equal ly even movement. So, an efficient counter flow process is achieved. BACKGROUND TECHNIQUE: In many industrial processes, a continuous chemical reaction between a solid material and a liquid or a gas is brought about, In the Swedish patent 8401478-6 it is described, among other things, how chemical reactions are brought about between a basic, solid material and harmful cont inuents in flue gases. The gases are led though a layer of granular limestone where the harmful sulfur dioxide, chlorhydric acid, fluorhydric acid, etc. reacts with sur¬ face of the stone, forming harmless products. In other processes, a reaction is desired between for instan- ce a substance that is dissolved or emulsified in a liquid and a solid material. Even in this case, the granular material is brought in contact with the liquid to reach the desired process on the sur¬ face of the solid material. Naturally the highest possible effici¬ ency of the process is preferred. The chemical process should run as completely and as fast as possible with a minimum consumption of solid material . The ideal counter flow process implies that the liquid or the gas is fed continually and evenly through a bed of the solid material of even thickness, that it is then led off the bed after the passage and that fresh solid material is fed at the surface, where the liquid or the gas is led off the bed and that this solid material is transported evenly downwards in the bed and is led off at the bottom surface of the bed. The liquid or the gas is thus introduced along the bottom surface of the bed where the solid material has been exposed for the longest time for the reac- ion and they leave the bed at the upper surface where fresh mate¬ rial is fed con inuously, Of course, the efficiency and the rapidi¬ ty of the process will be increased if the surface of the bed is made as large as possible. THE IMENTION: Surprisingly it has now appeared that an almost ideal counter flow process can be brought about in a simpler matter. In a closed vessel, the solid granular material is fed from a hopper above the vessel centrally through a hole or a slit. When the material mo*.'e=. continually down in the vessel, it simply flows out over the upper surface, the position and form of which is determined by the slide angle of the material . The liquid or the gas is fed evenly distri- buted under this surface at a distance from the surface, that cor¬ responds to the depth of the solid bed that is necessary to perform the chemical reactions. The liquid or the gas flows through the bed against the top surface and is evacuated from the space above the bed out from the closed vessel . Under the part of the bed that is participating in the reaction, the spent, solid material is moved downwards in such a way that the flow through the bed of granular material and fluid is as even as possible. The invention will be described more precisely in the enclos¬ ed claims, in a more detailed description below and by help of drawings enclosed on which: figure 1 shows a cross section of the vessel a figure 2 shows a method to let in the liquid or gas into the process and Figure 3 shows a situation with two funnels ,15, for illustrating the different terms in the formula. Closer description of the invention: Naturally, the closed vessel, fig. 1, can be designed in many, different ways, fi common and efficient design is described below. The vessel, fig.1, consists of a vertical, cylindrical part, 10, Upwards the cylindrical part ,10, is connected to an upper conical part ,11, ith the thin end upwards, and downwards to an¬ other lower conical part ,12, with the thin end downwards. The solid, granular material ,5, is filled centrally at the upper part of the upper conical part ,11, through a feed tube ,13, from a hop¬ per ,2, above the upper conical part ,11. The feed tube ,13, which is preferably mounted vertically is extending some distance down into the vessel ,fig 1. Naturally, the feed method can vary. For instance, the feed tube ,13, can be substituted to several feed tubes ,13, The reason the tubes ,13, should protrude down into the vessel ,fig. 1, is that the vessel is automatically filled as the solid granular material ,5, moves away from the mouth of the tube ,13. If the tube ,13, is designed as a telescope, the top level of the bed ,1, can easily be varied. In any case, there shall always be an open upper space ,9, that is free of solid material ,5, bet¬ ween the vessel wall on the top surface ,4, of the bed ,1. This open space ,9, allows the solid material ,5, to slide without ob¬ stacles over the top surface, 4, of the bed ,1. Now, depending of the slide angle of the solid granular mate¬ ial ,5, an upper surface ,4, sloping out and down from the feed tube ,13, is formed on the solid reaction bed , 1. The solid material ,5, is distributed over the bed ,1, in the same rate as the material ,5, in the bed ,1 , moves downward. How the l iquid or gaseous material shall be led to the bed ,1, evenly distributed over a surface in the bed giving a reaction zone of the preferred thickness. Normally, the thickness of the bed ,1, is equal over the whole area . Deviations can be necessary, for instance, if the grain sizes of the granulate ,5, varies as the larger grains easily con¬ centrate towards the periphery of the slide cone, However, the main factor governing the distance from the upper surface ,4, of the bed ,1, is then necessary extent of chemical reaction. The inflow of liquid or gas should be disturbed over as large area as possible without forming too much obstacle to the downward flow of solid, granular material ,5. This could for instance be ac¬ complished by mounting tubes with nozzles ,14, a3 spokeβ from a ring chamber ,7, around the cylindrical part ,10, of the vessel up- wards towards the center of the reac ion chamber. The slopes of the spokes should be chosen such that the thickness of the reaction zo¬ ne that is equal to the distance between the spokes and the upper surface ,4, is the chosen. Specially in case the fluid is gas, the tubes ,14, can be exchanged to long hoods ,16, which leave an open space free from granular material ,5, on their lower side and leave open channels for the gas. The cross section of the hoods ,16, can for instance have a U or a half circular form. The liquid or the gas that is led in flows through the reaction bed ,1, towards the upper space ,9, over the upper surface ,4, and is led away through the exhaust ,3, in the wall of the vessel. The granular material ,5, that moves down towards the area ,6, where liquid or gas enters the bed has now finished the chemi¬ cal reaction and shall be transported out of the bed. This trans- ort out of the bed must be done in such a way that the flow of the solid material ,5, through the bed ,1, is as even as possible over the total area in order to utilize the 301 id material ,15, as effi¬ cient ly as possible, Fig 1, shoves among others a number of concentric funnels ,15, that are mounted under the reaction bed. The granular material .5, is now conducted by the funnels ,15, towards the center of the reaction chamber and out of it at its bottom through an outlet ,8. The diameter of the bottom openings i the funnels ,15, and the length of the outlet tubes ,17, deter ines the distribution of the flow between the different funnels ,15, and, if the right di en- sions are chosen, the flow of solid material ,5, through the bed , 1 , will be quite even. On figure 3 a situat ion ith two funneIs ,15,15', is illust- rated. Here, Dt is the diameter of the lower, bigger funnel (15), dt is the diameter of the upper, smaller funnel (15'), d | is the inner diameter of the outlet tube (17') of the upper, s al ler funnel ( 15' ) , dy is the outer diameter of the outlet tube (17' .' ot the same tunnel (15') dn is the inner diameter of the outlet tube (17) of the lower bigger funnel (15), If is the distance from the bottom end of the outlet tube (17') from the. smaller funnel (15') to the outlet (17) of the bigger funnel (15), fill dimensions are given in meters. Now, the following formula gives the condition for an even flow in these two funnels ,15,: dt 2 x ((2 x If x constant + d n ) 2 - dy 2 ) = dj 2 x (Dt 2 - dt 2 ) The value of the constant is constant for every type of granular material ,5, but varies with different materials ,5, from 0,12 to 0,21. The right value for a certain granular material ,5, must be determined with an experiment. Once the value of the constant is determined, any type and dimension of funnel bed design can be calculated. In reaction beds with large upper surfaces ,4, it may be a problem that the natural slide angle and thus the depth of bed varies. For this reason a number of concentric rings can be mounted around the feed tube ,13, protuding a small measure down in the up¬ per surface ,4, of the bed ,1, thus controlling the upper level of the bed ,1. 0 C j- 0 5 0

Claims: CLfim 1. fl method to construct a counter flow process in α system with α solid, granular material (5) and a liquid or a gas c h a r a t e r i z e d b y a hopper (2), situated above a closed reaction vessel (fig.1) ith a vertical, cylindrical part (10) and a lower conical part (12) which tapers downwards from the central part (10) and the granular material (5) is moved by gra ity from the upper hopper (2) down to the center of the cylindrical part (10) and flows freely from the center out towards the cylindrical walls of the vessel over a surface (4) which is created by the slide angle of the gra¬ nular material (5), and that the material (5) is con inuously mowed downwards and out at the ou let (8), the liquid or the gas being introduced in the bed (1) evenly dist ibuted along a surface into the bed (1) of the granular mate¬ rial (5) which lies below the top surface (4) of the granular mate¬ rial bed (1) in such a way that the planned thickness of the reac¬ tion zone is formed and then led out of the bed (1) above the top surface (4) and the flow velocity of the granular material (5) downwards in the vessel being controlled to be even over the cross section of the bed (1). 2. fi method to construct a counter flow process according to claim l c h a a t e r i z e d b y the flow of granular material (5) in the bed (1) under the reaction zone being controlled by a number of concentric, circular funnels (15) with conical surfaces that are parallel to the lower conical part (12) of the reaction vessel and upper ends lie imme¬ diately below the reaction zone and end downwards with a tubular outlet (17) 3, fi method to construct a counter flow process according to claim 2 c h a r a t e r i z e d b y the distance from the bottom end of the outlet tube (17') from one funnel (15) to the outlet (17) of the next, lower funnel (15) being chosen from the formula: dt . 2 x ((2 x If x constant + d n ) 2 - dy 2 ) = dj 2 x (Dt. 2 - dt 2 ) where D is the diameter of the lower, bigger funnel (15), d is the diameter of the upper, smaller funnel (15'), dj is the inner diameter of the outlet tube (17') of the upper, 3mal ler funnel (15' ), dy is the outer diameter of the outlet tube (17') of the same funnel (15') d n is the inner diameter of the outlet tube (17) of the lower bigger funnel (15), If is the distance from the bottom end of the outlet tube (17') 5 from the smaller funnel (15') to the outlet (17) of the bigger funnel (15), all dimension in meters and the value of the constant varies with different materials from 0,12 to 0,21. 0 4. fl method to construct a counter flow process according to claim 1-3 c h a r a t e r i z e d b y the feed tube (13) ending downwards towards the upper surface (4) of the. bed (1). 5 5. fi method to construct a counter flow process according to claim 4 c h a r a t e r i z e d b y the tube (13) being telescopic. 6, fl method to construct a counter flow process according to any of 0 the preceding claim s c h a r a t e r i z e d b y the liquid or gas being fed under the reaction zone from a ring chamber (7) around its cylindrical part (10) through tubes with nozzles (14) and said tubes being arranged like spokes inwards and upwards from the rinq chamber (17) to the center of the vessel. 5 7. fl method to construct a counter flow process according to claim 6 c h a r a t e r i z e d b y the liquid or the gas being fed under the reaction zone (6) from the ring chamber (7) through U-shaped or semicircular hoods that 0 are open downward allowing gas or liquid to flow through without being filled with granular material (5). 5 40 45 A

Inventors: KARLSSON LEIF, TIBERG LARS, KARLSSON, LEIF, TIBERG, LARS
Applicants: KARLSSON LEIF, TIBERG LARS, KARLSSON, LEIF, TIBERG, LARS
Application year: 1996
Main classification: B01J8
IPC codes: B01D53, B01J8