KR20120090292A - Heat exchanger - Google Patents

Abstract

PURPOSE: A heat exchanger is provided to heat exchange waste water with fluids as an outer surface of the heat exchanger contacts with the waste water. CONSTITUTION: As to a heat exchanger, a convective flow in waste water moves the waste water along an outer surface of the heat exchanger(46). Fluids flow through the heat exchanger. The heat exchanger delivers heat to between the waste water and the fluids. The waste water flows through a container, and the convective flow is used for cleaning the waste water and the outer surface of the heat exchanger. The convective flow is made in the container by compressed aeration.

Description

Heat Exchanger

The present invention relates to a process for transferring heat between a wastewater in a vessel and a fluid by a heat exchanger in which a convection flow occurs in the wastewater and the wastewater moves along the outer surface and the outer surface is in contact with the wastewater; It relates to an apparatus for performing a process.

Wastewater can be domestic, municipal, commercial or industrial wastewater. For example, the fluid can be water, aqueous solution, alcohol or oil. Heat is transferred from the wastewater to the fluid to cool the wastewater or to heat the fluid. In particular, the heated fluid may be directed to the bypass by a heat pump to make the wastewater heat available for heating purposes. On the contrary, however, heat can also be transferred from the fluid to the wastewater to make it easier to handle by heating the wastewater.

The vessel may be a closed tank or an open basin. Waste water can flow continuously through the container or the waste water can be supplied and removed from the container in charge.

The heat exchanger is a hollow body in which fluid flows through its interior and its outer surface is in contact with the wastewater. When the temperature of the fluid and the waste water differs, heat is transferred through at least one heat exchanger wall, which is preferably made of a heat conducting sheath. The heat transfer capacity of the heat exchanger is proportional to the outer surface in contact with the waste water, the temperature difference between the two fluids, and the heat transfer coefficient (k value). k value is the inverse of the heat transfer resistance. This resistance is the sum of the resistances for heat transfer by fluid in the wall, for heat conduction through the wall, and for heat transfer from the wall to the surrounding wastewater. The resistance to heat conduction through the wall is controlled by the heat exchanger's geometry in proportion to the wall thickness and inversely proportional to the thermal conductivity of the wall material. On the other hand, the resistance to heat transfer from the fluid to the wall and vice versa is not only a function of the properties of the fluids (particularly their thermal conductivity, viscosity and heat capacity) but rather in particular of the flow mode. The inverse of the internal and external heat exchanger resistance is the coefficient of heat transfer (alpha value).

When the fluid is at rest, the alpha value is low, ie poor heat transfer. Heat transport relies on proper heat conduction as a result of dissipation and upon natural convection, ie, the flow generated by the altered density of the fluid when heated or cooled at the wall. Even better, ie high alpha values can be achieved by forced convection, ie artificially generated flow in the wall. The flows are characterized by their Reynolds number (Re), that is, proportional to the flow velocity and the characteristic geometric length (eg the diameter of the tube) and inversely proportional to the kinematic viscosity of the fluid.

For the low Reynolds number Re, the flow is laminar, and if it exceeds the critical Reynolds number, the flow becomes turbulent and the alpha value rises sharply. When a heat exchanger is used, it must therefore be attempted to have two fluids flowing in turbulent flow. It is simple to generate turbulence in the fluid pumped through the heat exchanger in that the flow rate is selected sufficiently high with or with it. If the outer alpha value is still low, the k value is not very useful for increasing the inner alpha value more and more. The required heat transfer capacity can only be achieved by a sufficiently large outer surface of the heat exchanger, which has the disadvantage that the heat exchanger becomes large and expensive. To avoid this, convection, preferably turbulent, must be generated in the wastewater along the outer surface of the heat exchanger.

Preferably, this flow should pass through the outer surface, ie have a direction that is nearly parallel to the outer surface. The high flow rate defined above the outer surface of the heat exchanger raises the alpha value, and the problematic solids or coatings are washed away from the outer surface, which makes the outer surface small and the price of the heat exchanger intact.

It is state-of-the-art to integrate heat exchangers into wastewater conduits or drains to transfer heat between the fluid flowing through the heat exchanger and the wastewater. Wastewater flows into conduits or drains passing through the outer surface of the heat exchanger. However, the flow rate is a function of not only the height in the conduit or drainage but also the amount of wastewater process through it. As a result, the height of the flow chart is not constant, thereby providing an unlimited flow. The flow is normally laminar flow. Turbulent conditions only take effect when the flow through them is very high, for example only after rain. As a result of normally low alpha values at the surface of the heat exchanger, it must have a large surface. In particular, if they are integrated into unpurified wastewater conduits, they are susceptible to contamination.

Published application DE 101 56 253 A1 teaches integrating a heat exchanger in an industrial water tank to further utilize the thermal energy given to industrial water at other locations. For this purpose, the industrial water must be stored in the tank in the middle, during which the air is blown and stirred. As a result of this agitation, industrial water flows past the outer surface of the heat exchanger, which improves heat exchange and at the same time washes off contaminants from the outer surface of the heat exchanger.

The published application DE 36 05 585 A1 also teaches a heat exchanger coupled to a wastewater vessel in which convective flow takes place on the outer surface of the heat exchanger. In this example, the flow occurs by moving the flexible wall of the wastewater container.

In addition, EP 0 174 554 B1 teaches a heat exchanger coupled to a vessel for contaminated water, which blows gas washing under the heat exchanger into the water to clean the outer surface of the housing and improve heat transfer.

According to these publications, convection flows are generated on the outer surface of the heat exchanger for the purpose of improving heat transfer and cleaning contaminants from the outer surface. Heat exchangers are always accommodated in vessels that are redundantly placed for this purpose where such water must be stored in the middle and guided through relatively expensive flow conduits formed by a plurality of heat exchangers. However, these devices add significantly to the investment and operating costs of the heat exchanger.

The present invention has the task of making a process that does not have the disadvantages cited and the apparatus for implementing the process possible, and allows the simple and economical utilization of the thermal energy given to the waste water. In particular, the present invention has the problem of further improving the energy balance by using devices which already exist for heat exchange.

This problem is solved by the process and the device according to the features of the independent claims.

Flowing vessels are a component of almost all wastewater purification plants and can additionally be used for heat transfer between wastewater and industrial water. Such vessels are already often provided with devices for producing convective flows which are used as assistants for cleaning the wastewater. These flows can be generated, for example, by agitation mechanisms or by blowing gas such as air into the wastewater. The use of this convection stream to clean the wastewater can, for example, prevent bottom sedimentation, thoroughly mix the wastewater, mix chemicals into the wastewater, accelerate the precipitation or flocculations, or air into the wastewater. May involve those that supply it. Thus, flow conditions are already provided at very different locations in the wastewater purification plant which can be further utilized for the actual task of improving heat transfer in the heat exchanger or cleaning the heat exchanger surface.

If these prerequisites are used, it is easy to achieve the utilization of the heat energy of the wastewater in the wastewater purification plant by coupling the heat exchanger to the appropriate location of the vessel through which the flow passes. The energy consumed is limited here only to the operation of the present heat pump, which is possible as well as to the operation of the current heat pump which results in the transfer of fluid through the heat exchanger. Convection streams not only recover heat but also serve to clean the wastewater, so the expenditure for this only occurs once. It is also proposed to integrate the heat exchanger inside the vessel through which the flow passes and cleans the waste water, since the waste water does not need to be stored intermediately in the tank in an expensive manner, resulting in lower investment and energy costs.

Wastewater cleaning can take place in industrial works or municipal sewage treatment plants. It may also be a wastewater cleaning, especially in hotels, apartment complexes, or office complexes, playgrounds or near areas. Dispersed wastewater treatment is particularly suitable for heating wastewater heat by means of heat pumps for heating, because the wastewater is relatively warm and there is a great demand for warmth for heating at close range.

According to a particularly advantageous embodiment of the process of the invention, the convection stream is produced in the waste water vessel by compressed aeration. In compressed aeration, air is blown into the wastewater to oxygenate the microorganisms and remove gaseous metabolic products such as carbon dioxide or nitrogen. When air is forced into the wastewater, air bubbles rise from the wastewater and attract the surrounding wastewater. In the region of the vessel into which the air is injected, a strong upward flow is made, and a corresponding downward flow is made at another location. According to a suitable arrangement of the aeration device, a distinct flow vortex with a flow rate of several meters per second can be produced by consuming less energy in the vessel. Preferably, air is supplied below or at an angle below the heat exchanger such that the upward flow overlaps the turbulence around the rising air bubbles. However, it is also possible to arrange the heat exchanger in a position where the flow is directed downward. In both examples, the outer surface of the heat exchanger should be approximately vertically aligned such that the wastewater flows with low flow resistance over the outer surface. Finally, it is also possible to arrange the heat exchanger in a position where the flow has a horizontal component, in which case the outer surface is preferably aligned parallel to the direction of the flow.

Convection flows are alternatively or additionally made in the vessel in favor of other means by surface aeration. Surface aeration devices are either rollers with horizontal axes or tops with a vertical axis for throwing a mixture of wastewater and activated sludge into the air or forcing air bubbles into the mixture for aeration. Surface aeration devices generate the strong convection flow required for aeration tanks.

According to another advantageous embodiment of the present invention, for example, using compressed air in a vessel such as a sand pit described in detail below to supply air to the wastewater and rising air bubbles create a swirling flow of wastewater. Suggest that. Vortex-like flows are produced in longitudinal vessels, in particular by blowing air around the side walls of the vessel. However, in a wide vessel, double flow vortices can also be made in that air is pushed around the central longitudinal axis of the vessel. Preferably, the heat exchanger is placed in an area where air bubbles blown in are raised upwards to create an upward flow of wastewater. However, the heat exchanger may be installed at the position where the wastewater flows back.

According to a particularly advantageous variant of the invention, an annular flow of waste water is produced in the vessel. Preferably, the annular flow is made in containers with a base area of circular or approximately square shape. Usually, wastewater flows up from the center and down from the periphery. However, the flow can have the opposite direction.

According to another embodiment of the process according to the invention, the flow is advantageously made with a stirrer in the vessel. This may be agitators that create an axial or radial flow. The type of agitator and its arrangement are in particular a function of the shape of the vessel. For long, rectangular vessels, horizontal propeller stirrers are used to generate flow along the longitudinal axis of the vessel. In the case of a circular or square vessel, the stirrer is preferably arranged on the vertical central axis. The latter may include stirring vanes to create a rotating flow or downward or upward propellers to create an annular or annular vortex flow in the vessel. In all these examples, the heat exchangers are preferably installed such that their outer surface is aligned parallel to the flow.

In addition, it is advantageous if the waste water is washed in sand pit. Sand pits are used to separate chunks of high rain density, ie sand, small gravel or stones. On the one hand, convection flows are created in a sand pit that is sized to keep organic matter suspended and, on the other hand, to prevent minerals from sinking. This convection flow can be further utilized to raise the alpha value on the outer surface of the heat exchanger placed in the sand pit. The convective flows produced in the sand pits for the separation of sand are very strong and clearly visible. Thus, it can be used particularly well for flow on heat exchangers. Sand pit containers are usually made of steel, complete with all parts and are delivered. Thus, it is particularly economical to integrate heat exchangers from factories into sand pit containers.

According to another advantageous variant, the wastewater is biologically purified. Biological purification usually takes place in the aeration basins of activated sludge plants. Part of all activated sludge installations is an aeration basin where air is supplied to the mixture of wastewater and activated sludge to oxygenate the microorganisms in the activated sludge and to release the metabolic products carbon dioxide and nitrogen as needed. Aeration basins are usually equipped with airtight aeration that blows air into the waste. It is particularly advantageous to mount heat exchangers in places where air is pushed in. When the heat exchanger is integrated into an existing aeration basin with airtight aeration, the existing convection flow is also utilized without any additional cost for heat exchange. However, the aeration basins of activated sludge plants may be equipped with surface aeration devices that generate convective flow.

In order to implement the above process, an apparatus for transferring heat between fluids is proposed as a means of a heat exchanger having wastewater and fluids flowing therethrough and having an outer surface in contact with the wastewater, wherein the diffusion pipe draws air. A batch and / or stirrer is arranged to create a convection stream for injection into the wastewater. According to the invention, the vessel here is a basin of wastewater purification facilities in which wastewater flows through it. These basins already include devices for the generation of convective flows which often support the action of mechanical, biological and / or chemical purification steps. In order to maintain the energy required for the lowest heat exchange possible, it is proposed to integrate into these vessels through which waste water flows since suitable flow conditions for heat transfer are already provided to them. Accordingly, the device according to the present invention is expected to have a particularly suitable energy balance by wastewater purification and heat recovery. Furthermore, none of the additional vessels or devices for making the flow are required for the recovery of the heat, saving significant investment costs.

The basins through which the wastewater flows are containers with inlets and outlets. These are actually part of every wastewater treatment plant. The basins may be open or closed at the top. A diffusion pipe is a horizontally arranged pipe having an opening through which compressed air is supplied, through which air is compressed into waste water in the form of coarse droplets. Alternatively, the diffusion pipe may be equipped with a porous or grooved aeration element in which air is forced into the waste water in the form of somewhat fine bubbles.

The basin through which the flow passes is advantageously the aeration basin of the activated sludge plant, which serves as a biological purification of the wastewater and is produced by the aeration apparatus. In activated sludge plants, the organic components of the wastewater are metabolized and converted into biomass by microorganisms. Biomass is separated from the final clarification basin, for example so-called activated sludge, and returned to the aeration basin. Biomass cultivation is removed from the final clarification as so-called excess sludge.

According to a particularly advantageous embodiment, the basin is a sand pit. Mechanical prepurification of the waste water takes place in the sand pit, in particular by the separation of the sinking material of heavy particulates. To this end, a convective flow is created which is so strong that particularly low density organic materials are suspended.

According to another embodiment, the sand pit is advantageously a circular sand pit in which a stirrer is formed which creates an annular flow at its center. Since the stirring devices are usually coupled to a circular sand pit to create a rotating annular flow, the waste water flows to the center in a spiral path above the bottom of the sand pit. The mineral masses are pushed in the direction of the center by this flow and settle down through the annular slot into a recovery chamber located below, for example under the floor. It is proposed to arrange the heat exchangers around a circular sand pit where the waste water flows down. Alternatively, they may be arranged annularly around the stirring device, in which case the waste water flows upwards in these areas.

Instead, it is advantageous if the sand pit is a long sand pit with side walls and at least one diffusion pipe disposed around the longitudinal wall and along the longitudinal wall for blowing air and creating a swirling flow. In long sand pits, the vortex flow is customarily created by blowing compressed air along one of the longitudinal walls. According to the invention, this vortex flow is further useful for improving the heat transfer of heat exchangers arranged in air-filled sand pits.

In another embodiment of the invention, the heat exchanger advantageously comprises an inlet and an outlet for the fluid, which are connected to each other by at least one flow conduit, wherein the outer face of the flow conduit forms the outer face of the heat exchanger. The fluid flows preferably in a swung manner through the flow tube from the inlet to the outlet. In order to lower the through flow and to maintain a high temperature difference between the inlet and outlet, the flow conduit must have a small hydraulic diameter and be long. The flow conduit is delimited by walls whose at least one outer surface forms the outer surface of the heat exchanger. Fluid flows along the inner surfaces of the walls, and wastewater flows along the outer surfaces of the walls.

And it is particularly advantageous if the flow conduit is formed by pipe sections having a circular, rectangular or square cross section. The flow conduit is thus produced from a series of commercial pipe profiles whose outer surface forms the outer surface of the heat exchanger.

According to a particularly advantageous embodiment, the pipe sections are aligned substantially horizontally. This alignment is particularly advantageous if the vessel in which the heat exchanger is placed is flat. In this example, the flow against the pipes is oblique.

However, in special cases, for example in deep containers, it may be advantageous if the pipe sections are aligned substantially vertically. In this case, the flow against the pipe is longitudinal, which has the advantage that the pipes create a low flow resistance and thus only weaken the convective flow in the basin.

The pipe sections are advantageously arranged in parallel and have ends connected to each other, so that the fluid of adjacent pipe sections on the fluid side flows in the opposite direction. Thus, the fluid flows back and forth in parallel pipe sections. This results in a simple way that the heat exchanger has a long flow conduit even with small dimensions. The connection between adjacent pipe sections is caused by vertical connecting pipes. If the rectangular or square pipe sections are arranged parallel to one another without a gap, their ends can be connected to one another by an opening, for example holes.

According to another advantageous variant of the invention, the flow conduit is formed by at least one hollow profile arranged in the form of a spiral with a vertical axis. For example, the hollow profile can be a round or rectangular pipe profile. Even in this variant, the pipes are arranged in parallel to form a long flow conduit. Since there is no steep warpage, the flow resistance is particularly low in terms of flow. This variant is particularly suitable for circular containers.

In another advantageous embodiment, the outer surface of the heat exchanger extends substantially parallel to the convective flow and is flat or corrugated. The heat exchanger should have the lowest flow resistance possible for convective flow. Thus, since its outer surface must extend parallel to the flow, the wastewater can flow without obstruction at its outer surface. If rectangular profiles are arranged in parallel with no gaps or little spacing, they form a flat outer surface for the flow. If the profile sheets are connected to one another as modern heaters, they have a corrugated outer surface. If the circular pipes are arranged in parallel, they form an approximately corrugated outer surface, even if there is a gap between them. This is the ideal outer surface wrapped.

This is also advantageous if the outer face of the heat exchanger is at the same time the inner face of the vessel wall. In this embodiment, the heat exchanger is an integral part of the wall of the vessel. This has the advantage that the heat exchanger generates only very low additional resistance for convective flow without generating additional resistance.

This is also an advantage if the flow conduit of the heat exchanger is formed by hollow spaces between the vessel wall and the profiles attached thereto. The profiles are partial profiles, such as half pipes, U-shaped profiles or L-shaped profiles. The profiles can be attached to the interior of the vessel wall. However, in the case of a metal vessel, the profiles can be attached to the outside of the vessel wall such that the vessel wall forms the heat transfer outer surface of the heat exchanger.

According to another advantageous embodiment, the device comprises a movable brush for cleaning the outer surface of the heat exchanger. The brushes are moved by the drive on the outer surface of the heat exchanger to remove the adhesive mass or coatings.

Another possibility for cleaning the outer surface of the tubes of the heat exchanger can be realized by cleaning rings. The rings are made of plastic or equivalent material and move on the tube surface and have an inner diameter corresponding to the outer diameter of the heat exchanger tube so that the attachment can be scraped from the tubes. It may be advantageous for maintenance if the rings comprise two or more separate parts (eg in the form of a semicircle) that are detachably connected (eg by tongue and groove connections). Some rings may be located between two opposing metal or plastic guide members, which in turn are moved by corresponding drive members.

Alternatively, it may be advantageous for the outer surface of the heat exchanger to be cleaned by movable spray nozzles. Preferably, the sprinkled water is removed from the outlet of the wastewater purification plant, so it is very free from the mass and the nozzles are not clogged.

Furthermore, the advantages of the invention are described in the following examples.

A process for transferring heat between the wastewater in the vessel and the fluid by a heat exchanger in which convective flow occurs in the wastewater and the wastewater moves along the outer surface and the outer surface is in contact with the wastewater and performs the process It provides a device to.

1 is a schematic longitudinal cross-sectional view of an air-filled long sand pit with a heat exchanger disposed therein;
FIG. 2 is a schematic cross sectional view of the long sand pit supplied with air of FIG. 1; FIG.
3 is a schematic longitudinal cross-sectional view of a spherical sand pit with an agitator and heat exchanger disposed therein;
4 is a schematic longitudinal sectional view of an aeration basin supplied with compressed air in which a heat exchanger is disposed;
5 is a schematic longitudinal cross-sectional view of another aeration basin with surface aeration in which a heat exchanger is disposed;
6 shows an apparatus for cleaning the outer surface of a heat exchanger.

1 and 2 show a sand pit 1 having a rectangular base area. The sand pit 1 consists of a basin 2 having an inlet 4 and an outlet 6 for wastewater flowing through the sand pit 1. The basin 2 may be made of concrete, metal or plastic. The basin 2 is filled with wastewater up to a certain water level 8. The basin 2 has vertical front walls 10, 12 and side walls as well as oblique bottom regions 18, 20 which are inclined towards the drain 22 so that the sand placed in the sand pit 1 slides toward the drain 22. Have 14, 16. A worm conveyor 24 is disposed in the drain 22 and driven by a motor 26 to push the separated sand into a sump 28. The sand is discharged by the pump 30 from the sump 28 and is usually transferred to a sand sorter or a sand washer (not shown). The pump 30 may be a rotary pump or an air-lift pump or compressed-air lift pump.

The sand pit 1 shown, the long sand pit in this embodiment, is supplied with air. Air is supplied from a blower (not shown) through a compression line 32 to a distribution pipe 34 arranged horizontally around the side wall 14, through which the pipe 36 has a hole 36. Is forced into the wastewater. The forced air rises up to the water surface 8 in the form of air bubbles 38 in the wastewater, creating a strong convection flow over the diffusion pipe 34 which is directed upwards parallel to the side wall 14. At the periphery of the opposing side wall 16, the wastewater flows down and back into the diffusion pipe 34. Accordingly, aeration creates a substantially swirling flow in the sand pit 1 indicated by the arrows in the figures. The flow over the bottom regions 18 and 20 is so strong that low density organic masses, such as sediment, are swept upwards while the high density inorganic materials remain in the bottom regions 18 and 20. The wastewater flows down from the slightly inclined bottom face 20 and pushes the sand deposited thereon towards the drain 22. This prevents organic bottoms from forming and the wastewater is completely mixed, so that chemicals can also mix better with the wastewater. In addition, precipitations or flocculations may be accelerated, resulting in improved wastewater purification.

The separating wall 40 separates the fat capture chamber 42 from the sand pit 1. Conventionally, the dividing wall 40 is a finishing portion in which rising substances, such as fat and oil, enter the fat capture chamber 42 where it is obscured from the flow and rise therein to form a layer 44 floating on the water surface 8. (perorations, not shown). The floating layer 44 is pushed along the fat capture chamber 42 by a removal shield (not shown) into a funnel that can be discharged by a pump.

According to one embodiment, the air bubbles 38 rise with the flow made in the wastewater along the outer surface 48 of the heat exchanger 46 to contribute to cleaning the outer surface 48 of the heat exchanger 46. The heat exchanger, having an outer surface 48 in contact with the waste water, is arranged above the diffusion pipe 34 below the water surface 8 and in the surrounding sand pit 1 of the side wall 14. However, the heat exchanger 46 may be disposed over the perimeter or separation wall 40 or bottom 20 of the opposing side wall 16 such that the wastewater flows down on the outer surface 48.

According to one embodiment, the heat exchanger 46 consists of a series of pipes 50 arranged in parallel with intermediate spaces 52 therebetween. However, the heat exchanger may consist of hollow profiles, for example square profiles. In addition, the hollow profiles can be arranged horizontally or vertically without the intermediate spaces 52.

The heat exchanger 46 includes an inlet pipe 54 and an outlet pipe 56 for fluid flowing therein through the pipes 50 forming the heat exchanger 46 and the long flow conduit 220. Pipes 50 are connected to each other at their ends by pipe corners 58 so that fluid flows in opposite directions in adjacent pipes 50. This first turns the flow conduit 220 to pipe 50 as long as possible to have a wide outer surface 48. Second, even with small through-flows, it is achieved that fluid flows rapidly through the heat exchanger 46 and continuously through the pipe 50, so that the alpha value on the flow side is high. Third, this allows the heat exchanger to be short and compact even with a wide outer surface 48.

3 shows a circular sand pit 100 having a vertical axis 102, a circular basin 2, a circumferential wall 104, a bottom 106, an inlet conduit 108, and an outlet conduit 110. The inlet conduit 108 and the outlet conduit 110 flow into the basin 2 substantially in a tangential direction, thereby creating a rotating flow therein and a low pressure loss while the wastewater passes through the circular sand pit 100. maintain. A recovery chamber 112 is disposed below the basin 2 for the separated sand. The recovery chamber 112 is separated from the basin 2 by the bottom plate 114, and includes a pool 28 through which the mandrel-shaped drain pipe 116 runs. This allows the separated sand to exit vertically from the pond 28 by means of a pump device or a compressed air pump (not shown) and is fed to the sand sorter or sand washer (not shown) via line 118.

A hollow rotating shaft 120 to which a pinwheel 122 such as a propeller is attached is disposed coaxially around the drain pipe 116. The hollow shaft 120 is driven by the motor 124 via the transmission 126. The axial upward flow of the wastewater is generated by the rotation of the pinwheels 122 in the basin 2. The formation of this upward flow is supported by a guide ring 128 disposed coaxially around the pinwheel 122. The wastewater flows outward rapidly below the water surface 8, and the wastewater flows down around the perimeter wall 104. On the bottom 106 and the bottom plate 114, the water quickly flows to the hollow shaft 120 and returns to the pinwheel 122. The direction of flow of the toroidal is shown by the arrow. This annular flow is connected to the rotational flow about the vertical axis 102 generated by the water tangentially flowing through the inlet conduit 108 and the outlet conduit 110 on the one hand and by the rotation of the pinwheel 122 on the other hand. Overpowered by

In particular, dense solids, such as sand, are pushed by an annular flow in the inner radial direction towards the center of the basin 2 on the other hand, on the other hand, by rotation as a result of the so-called teacup effect. They sink to the bottom 106 and the bottom plate 114 and are pushed in the direction of the axis 102. An annular slot 130 is disposed between the bottom plate 114 and the hollow shaft 120 through which the sand sinks into the recovery chamber 112. Less dense organic matter, on the other hand, is suspended by this flow and flows into the outlet conduit 110 primarily with wastewater. This gives the sand pit 1 good selectivity, which means on the one hand that less sand remains in the waste water and on the other hand only a small amount of organic matter is released with the sand.

The heat exchanger 46 is disposed below the water surface 8 and in the peripheral basin 2 of the circumferential wall 104. Fluid flows through the inlet pipe 54 and the annular pipe 50 to the outlet pipe 56. The annular pipe 50 forms the flow conduit 220 of the heat exchanger 46. The fluid flows from the outlet pipe 56 back to the inlet pipe 54 via a heating or cooling device such as a heat pump (not shown) in which the fluid is heated or cooled in a bypass. While the fluid flows through the pipe 50, it is given heat through the outer surface 48 of the pipe 50 to cool or to receive heat from the wastewater. In one embodiment, the heat exchanger 46 consists only of a single annular pipe 50. Of course, this may consist of a spirally formed pipeline.

According to one embodiment, the heat exchanger 46 is disposed around the circumferential wall 104 such that the wastewater flows down on the outer surface 48 of the heat exchanger 46. However, the heat exchanger 46 can also be placed elsewhere in the annular flow; For example, the guide ring 128 can be designed as a heat exchanger 46, in which case its outer surface 48 facing the axis 102 is exposed to a very strong axial and rotational flow.

4 shows an aeration basin 200 with surface aeration. A mixture of wastewater and activated sludge is provided in the basin 2. The basin 2 shown in this embodiment is circular and has a vertical axis 202, a base 204, and a circumferential wall 206 made in the embodiment of the metal sheet. A bridge 208 is placed on top of the basin 2 to accommodate the motor 210, the transmission 212 and the aeration top 214 rotating around the vertical axis 202. The aeration top 214 pulls the mixture of wastewater and activated sludge upwards in the region of the shaft 202 and throws it outward radially above the water surface 8. At this time, air bubbles 216 enter the mixture of wastewater and activated sludge to supply a mixture with oxygen. A distinct annular flow occurs in the basin 2 that faces up in the region of the axis 202 and down around the perimeter wall 206.

Half of the pipe profiles 218 form a circumferential wall such that a spiral flow conduit 220 is formed between the circumferential wall 206 and the half flow conduit 218 that flows fluid from the inlet 222 to the outlet 224. 206 is attached around. The circumferential wall 206 and the half pipe profiles 218 attached thereto form the heat exchanger 46. The interior of the circumferential wall 206 is simultaneously the outer surface 48 of the heat exchanger 46. The outer surface of the circumferential wall 206 is the inner surface 228 of the flow conduit 220 which simultaneously passes through the heat exchanger 46. Fluid flows through the flow conduit 220 of the heat exchanger 46 and a mixture of wastewater and activated sludge flows along the outer surface 48 of the heat exchanger 46. Thus, a portion of the circumferential wall 206 serves to transfer heat from the wastewater to the fluid or vice versa.

In the case of a swollen flow of fluid in the flow conduit 220 and in the case of waste water on the outer surface 48, it has a high alpha value for the transfer of heat. Perimeter wall 206 should be as thin as possible in the area of heat exchanger 46 to achieve good thermal conductivity through perimeter wall 206. Since the circumferential wall 206 is reinforced by half of the pipe profiles 218 to which it is attached, the circumferential wall 206 can be made thin in the region of the heat exchanger 46.

While half of the pipe profiles 218 are shown in this embodiment in contact with each other, they may be attached at intervals. Of course, it is also possible to use angular profiles.

5 shows an aeration basin 200 with pressure aeration. The rectangular basin 2 has a flat base 204 and vertical walls 250 and 252. Diffusion pipes 34 are disposed above the base 204 around the vertical wall 250 so that compressed air is blown into the pipes by a blower (not shown). Aeration elements 256 are disposed in the diffusion pipes 34 and are plate-shaped in this embodiment. However, other pipe-shaped or plate-shaped aeration elements 256 may also be used, for example. The aeration elements 256 include membranes with porous bodies or slots through which the supplied compressed air in the form of fine air bubbles 216 is filled in the wastewater. They rise to the water surface 8 and generate upward convective wastewater flow around the perimeter of the vertical wall 250. Wastewater flows back down the periphery of the facing vertical wall 252. A whirlpool-like flow occurs in the basin (2), the direction of which is indicated by an arrow.

A heat exchanger 46 having a flow conduit 220 through which fluid flows is disposed in place above the aeration element 256, in which wastewater flows up along the outer surface 48 of the heat exchanger 46.

The heat exchanger 46 of this embodiment is the corrugated sheets 258 connected to each other such that longitudinal hollow spaces 262 are created between the two corrugated sheets 258 and 260 forming the flow conduit 220. , 260). Adjacent hollow spaces 262 are connected to each other at their ends such that fluid flows continuously in alternating directions through some hollow spaces 262. The sheets 258, 260 are vertically aligned so that the rising wastewater can flow along them without significant resistance.

In this embodiment, the heat exchanger 46 may be oriented such that the hollow spaces 262 extend horizontally. However, the heat exchanger 46 may be arranged to rotate 90 degrees so that the hollow spaces 262 extend vertically.

6 shows a heat exchanger 46 arranged in the basin 2 and also shows a cleaning device 300 according to the invention. The heat exchanger 46 forms a flow conduit 220 for the fluid, and fluid flows from one square pipe 302 to the adjacent square pipe 302 such that the fluid flows in opposite directions from the adjacent square pipes 302. Flowing perforations, for example, are made of several square pipes 302 parallel and horizontally arranged at both ends with holes (not shown).

The heat exchanger 46 has two parallel and vertical outer surfaces 48 constituted by opposing faces of the square pipes 302. The wastewater flows upwardly by convection along the vertical outer surface 48 of the heat exchanger 46, which can be generated, for example, by blowing air under the heat exchanger 46.

The cleaning device 300 includes brushes 308 that can be moved horizontally to clean them from adhesive masses and coatings on the outer surface 48 of the heat exchanger 46. The soles 308 are attached to a fork-shaped holder 310 connected to the transmission 312. At least one wheel axle 314 with wheels 316 at both ends extends horizontally through the transmission 312. The wheels 316 move over the rail or bearing surfaces 318 of the basin wall 320. The cleaning device 300 is moved by the rotation of the threaded rod 322 extending through the transmission 312. On the contrary, it is also possible to move the cleaning device 300 by a cable or chain drive. Instead of the brush 308, spray nozzles may be provided in the cleaning device.

The present invention has been described in detail using the examples. However, it is not limited to the above examples shown and described. Modifications are possible at any time within the scope of the protection claims.

1: sand pit 2: basin 4: inlet 6: outlet
10, 12: vertical front bricks 14, 16: side walls
18, 20: floor areas 22: drainage
24: warm conveyor 26: motor 28: puddle 30: pump
32: compression line 34: distribution pipe 36: hole 38: air bubbles
40: partition wall 42: fat capture chamber 46: heat exchanger 48: outer surface
50: pipes 52: intermediate spaces 54: inlet pipe 56: outflow pipe
58: corners

Claims (24)

The convection flow created in the wastewater moves the wastewater along the outer surface 48, where the fluid flows through it and is located in the fluid and the vessel by a heat exchanger 46 having the outer surface 48 in contact with the wastewater. In the process for transferring heat between the wastewater, the wastewater flows through the vessel and the generated convection flow is used to clean the wastewater and at the same time clean the outer surface 48 of the heat exchanger 46. A process, characterized in that it is used to. The method of claim 1,
Said convection stream being produced in a vessel by compressed aeration. 3. The method according to any one of claims 1 to 3,
Said convection flow is produced in the vessel by surface aeration. 4. The method according to any one of claims 1 to 3,
The wastewater is supplied with compressed air from the vessel, in particular from a sand pit, and the rising air bubbles (38, 216) create a vortex-like flow of wastewater. 5. The method according to any one of claims 1 to 4,
A toroidal flow of said wastewater is produced in said vessel. The method according to any one of claims 1 to 5,
Wherein said convection flow in said vessel is made by an agitator. 7. The method according to any one of claims 1 to 6,
Said waste water is purified in a sand pit (1). 8. The method according to any one of claims 1 to 7,
Said wastewater is biologically purified. Position the diffusion pipe 34 to force air and / or agitator to create a convective flow that moves the wastewater along the outer surface 48 such that fluid flows through and contacts the wastewater. In an apparatus for transferring heat between the fluid and the wastewater located in the vessel by a heat exchanger 46 having a face 48, the vessel is the basin of the wastewater purification plant through which the wastewater flows. Device characterized in that. 10. The method of claim 9,
The basin (2) is characterized in that the aeration basin (200) of the activated-sludge equipment. The method according to any one of claims 9 to 10,
The basin (2) is characterized in that the sand pit (1). 12. The method according to any one of claims 9 to 11,
The sand pit (1) is a device characterized in that the spherical sand pit (100) is arranged in the center of the stirrer to create an annular flow. 13. The method according to any one of claims 9 to 12,
The sand pit 1 is longitudinally provided with side walls 14 and 16 for forcibly pushing air to create a vortex-like flow and at least one diffusion pipe 34 disposed along the side walls 14 and 16. Apparatus characterized in that the sand pit. The method according to any one of claims 9 to 13,
The heat exchanger 46 comprises inlets 4, 222 and outlets 6, 224 for the fluid connected to each other by at least one flow conduit 220, the outer surfaces of the flow conduit 220 being And an outer surface (48) of the heat exchanger (46). 15. The method according to any one of claims 9 to 14,
The flow conduit (220) is characterized in that it is formed by pipe zones having circular, rectangular or square cross-sectional areas. 16. The method according to any one of claims 9 to 15,
Said pipe sections being substantially horizontally aligned. The method according to any one of claims 9 to 16,
Said pipe sections being substantially vertically aligned. The method according to any one of claims 9 to 17,
Said pipe sections being arranged in parallel and having ends connected to each other in such a way that said fluid flows in opposite directions on said fluid side in adjacent pipe sections. The method according to any one of claims 9 to 18,
Wherein said flow conduit (220) is formed by at least one hollow profile disposed in the form of a spiral having a vertical axis (102). The method according to any one of claims 9 to 19,
Wherein the outer surface (48) of the heat exchanger (46) is substantially parallel and flat or corrugated to the convective flow. The method according to any one of claims 9 to 20,
Wherein the outer surface (48) of the heat exchanger (46) is also at the same time the inner surface of the vessel wall. The method according to any one of claims 9 to 21,
The flow conduit (220) of the heat exchanger (46) is characterized in that it is formed by hollow spaces (262) between the vessel wall and the profiles affixed to the vessel wall. The method according to any one of claims 9 to 22,
The outer surface (48) of the heat exchanger (46) is characterized in that it is cleanable by movable brushes (308). The method according to any one of claims 9 to 23,
Wherein the outer surface (48) of the heat exchanger (46) is cleanable by movable spray nozzles.

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