GB2170586A

GB2170586A - Regenerative heat-exchange element and heat storage mass formed therefrom

Info

Publication number: GB2170586A
Application number: GB08602449A
Authority: GB
Inventors: Siegfried Schluter
Original assignee: Apparatebau Rothemuehle Brandt and Kritzler GmbH
Current assignee: Apparatebau Rothemuehle Brandt and Kritzler GmbH
Priority date: 1985-02-02
Filing date: 1986-01-31
Publication date: 1986-08-06
Also published as: DK35886D0; JPS61180890A; NL8600103A; AU5278786A; GB8602449D0; DK35886A; DE3503607A1

Abstract

An element for the construction of heat storage masses or storage material in the regenerative chamber of regenerative heat exchangers is a block (10) with a plurality of parallel throughflow ducts (13) which are separated from one another by walls (15) and (16) and are situated in each case adjacent to one another in the direction of its cross-section width (11) and cross-section height (12). The block is formed as a one-piece extrusion moulded article from a synthetic plastic material. <IMAGE>

Description

SPECIFICATION Regenerative heat-exchange element and heat storage mass formed therefrom The invention relates to a moulded element made of synthetic plastic material for regenerative heat transmission in heat exchangers, with a plurality of throughflow ducts for the exchange media, which ducts are delimited relatively to one another by means of walls in a honeycomb formation. But it also relates to a heat storage mass formed from such moulded elements.

Moulded elements of the kind specified, then, are used for the construction of heat storage masses in the regenerative chamber of regenerative heat exchangers. One possibility is for these regenerative heat exchangers to be provided with a fixed, or stationary, regenerative chamber with which rotating supply and discharge hoods for the various exchange media are then associated; alternatively it is possible to use rotatable regenerative chambers with which stationary supply and discharge hoods for the various exchange media are then associated.

Especially in those fields of use for regenerative heat exchangers where it is a question of preheating boiler exhaust gases which have been previously purified in a wet cleaning stage, there is a considerable risk of fouling and corrosion to the regenerative heat exchanger. Deposits or securely adhering coatings may form in the heat storage mass, and this not only prejudices and transfer of heat but also lead to gradually reducing the crosssection width of the throughflow ducts for the exchange media.

To reduce the risks of fouling and corrosion to heat storage masses in regenerative heat exchangers of steam boiler installations, it is also already known for the heat storage masses in the regenerative chamber to be constructed from panels of synthetic plastic material stacked one above the other, in such a manner that between each two plane synthetic plastic material panels a synthetic plastic material panel with a corrugated or beaded profile is provided for forming the throughflow ducts for the exchange media (periodical "Energie" 32nd year, No. 12, December 1980, pages 463 to 465).But irrespectively of whether the heat storage masses for the regenerative chamber of regenerative heat exchangers comprise stacked metal or synthetic plastic material panels such that throughflow ducts delimited from one another are formed between the said panels for the exchange media, there is a considerable resulting production outlay, as can be seen merely from e.g. US-PS 23 13 081. This is because the individual panel elements, whether they are substantially flat or have longitudinal profiling for forming the throughflow ducts, come in many different width sizes for fitting into the sections of the regenerative chamber which are subdivided in the manner of ring segments, and also always have to be assembled into a very specific ring segment zone.

The last-mentioned disadvantage occurs in every case if heat storage masses of regenerative heat exchangers are built up from sheetform or panel-form individual elements i.e.

even if these panel elements are of substantially level form and have strips placed on them as spacer elements, as for example DE-PS 3207213 shows.

A further disadvantage of such heat storage masses consists in that a storage mass assembly of this kind assembled from component elements e.g. by means of ultrasonic welding, cannot take high mechanical loads and therefore is easily damaged during the course of cleaning operations using water, steam or air jets.

The invention has as its object to provide a possibility which not only ensures simple and economical production of basic elements for forming heat storage masses, but also at the same time substantially facilitates fitting-out the regenerative chamber of regenerative heat exchangers with heat storage masses, or with storage material of high inherent strength, and is also to a very considerable extent insusceptible to the kind of narrowing or clogging of their or its exchange media throughflow ducts which is so very undesirable.

According to the invention a regenerative heat exchange element is formed as a onepiece extrusion moulded article, with a honeycomb of parallel-arranged ducts which each extend in the direction of its cross-section width and its cross-section height adjacent to one another and are delimited from one another by the walls. The ducts are adjacent to each other in both cross-sectioned directions (width and depth) of the element and extend parallel in the direction of its length.

Thus there are provided moulded elements made of synthetic plastic material which are formed in a single manufacturing operation with a predetermined cross-section and length, and having a likewise predetermined number of and predetermined positions for throughflow ducts. Accordingly by associating a plurality of identical or similar moulded elements with one another in the manner of building elements it is possible to build up in the regenerative chamber of a regenerative heat exchanger an optimally effective heat storage mass which is not prone to fouling. For practical use it has been found particularly satisfactory if each element corresponds or is adapted, at least in its cross-sectional form, to the geometric form and/or dimensions of the compartments in the regenerative chamber.

For forming the moulded elements, synthetic plastic material is used which not only has advantageous heat transfer properties for the purpose intended according to the present invention, but also at the same time counteracts any caking-on of impurities carried along in the exchange media, for example salts and soot particles carried along in water droplets.

It has been found particularl satisfactory if the hydraulic diameter of the throughflow ducts is in a ratio of between 1:0.2 and 1:0.3 approximately in relation to the thickness of the walls demarcating the said ducts from one another.

The element may be of polygon form with its plan geometrically similar to the cross-sectional form of the individual throughflow ducts; for example the individual throughflow ducts in the block may have a square or rectangular cross-section and the block also has a square or rectangular plan. It has also been found useful to give the individual block a length which is to the hydraulic diameter of the ducts in a ratio of between 10:1 and 50:1 approximately.

For practical uses it has been found especially recommendable to use such block-form extrusion moulded articles of synthetic plastic material using a plan or cross-sectional area with side lengths of between 100 mm and 300 mm, and lengths in the direction at right angles to this plan or cross-sectional area of between 150 mm and 500 mm. The crosssection side lengths for the individual throughflow ducts within the block are advantageously between 7 and 10 mm, whilst the walls within the block which separate adjacent throughflow ducts from one another can be made with a thickness of between 1.5 and 3 mm.

The plane outer boundary of each block consists of plane walls all round, and the thickness of the plane boundary walls can correspond to about half the thickness of the walls which separate the ducts from one another within the element.

It is also possible as set to insert each block in its own sheet metal jacket. But this jacket may also consist of another material, preferably a corrosion-resistant laminated material which is suitable for receiving a block.

The block inserted in such a jacket can correspond in its cross-section form to the geometric form and/or size of the compartments in the regenerative chamber, being extruded already dimensionally true for fitting into the jacket. Alternatively, however, it may also be cut to size from a previously produced extrusion moulded article in conformity with the geometric form and/or dimensions of the compartments in the regenerative chamber before being inserted in the jacket.

In another aspect of the invention a heat storage mass or a storage materiak for a regenerative heat exchanger (which is more preferable with a stationery regenerative chamber, but may if appropriate be one with a rotating regenerative chamber) includes a plurality of one-piece extrusion moulded articles constructed as individual elements inserted in a chamber housing and/or framework in an arrangement wherein they are stacked side by side and one above the other (in the manner of building blocks), all the blocks with their throughflow ducts taking up a like-orientation in the chamber housing and/or framework, the element stacked one above the other in the longitudinal direction of the throughflow ducts being positioned with their throughflow ducts in register with one another.

A heat storage mass or storage material for regenerative chambers having an annular boundary, with a chamber framework subdivided in ring segment manner is arranged such that the boundary surfaces of the individual, ring segment shaped, portions of the chamber framework are provided with plane supporting or abutment regions the size of which is in each case adapted to the cross-section side lengths of an individual block or extrusion moulded article, and that these supporting or abutment regions are in each case situated at least in the joint region between two block stacks placed one above the other.In a final aspect, a heat storage mass suitable for insertion in the regenerative chamber of such regenerative heat exchangers whose chamber housing and/or framework is subdivided into a plurality of individual compartments, has the filling of at least some of the compartments formed of several blocks (elements) which complement one another to make up a crosssection corresponding to the compartment.

It will be apparent that by using the measures proposed by the present invention, and on the basis of individual standardised moulded elements made of synthetic plastic material, it is possible to produce heat storage masses or storage materials for regenerative heat exchangers which can, with a small assembly work outlay, be adapted to very many different fitting or assembly conditions in regenerative chambers and, whilst having good inherent strength, also allow local interchanging of individual moulded elements if necessary should these be damaged or have blocked or excessively narrowed throughflow ducts.

Further features and advantages of the invention will be described hereinafter with reference to constructional examples shown in the drawings. In the drawings: Figure 1 shows in perspective and approximately in its natural size a block or moulded element for the construction of a heat storage mass or storage material in the regenerative chamber of a regenerative heat exchanger, Figure 2 shows in simplified diagrammatic manner, in plan view, a regenerative chamber with an annular outline for a regenerative heat exchanger having a chamber housing or framework subdivided in ring segment manner, the heat storage mass or storage material being shown only in one ring segment thereof-for the sake of simplicity, Figure 3 shows on a larger scale the portion of a regenerative chamber for a regenerative heat exchanger which is indicated as Ill in Fig.

2, Figure 4 is a plan view corresponding to Fíg. 2 of a constructionally modified regenerative chamber for regenerative heat exchangers, Figure 5 shows on a larger scale the region of the regenerative chamber which is indicated as V in Fig. 4, Figure 6 is a perspective view of a block or moulded element for the construction of a heat storage mass or the heat storage material of the regenerative chamber of a regenerative heat exchanger, this block or the like having a trapezoidal plan and showing the throughflow ducts therein with different opening cross-sections-for the sake of simplicity.

Fig. 1 of the drawings shows in perspective a moulded element 1 suitable for the construction of heat storage masses 2 in the regenerative chamber 3 of regenerative heat exchangers, as indicated e.g. in Figs. 2 and 3.

Figs. 2 and 3 also show that the heat storage mass 2 consists of a large number of individual moulded elements 1, these moulded elements being arranged in the regenerative chamber 3 stacked side by side and one above the other. The regenerative chamber 3 can have annular boundaries through provision of an outer shell 4 and an inner shell 5, and may also be subdivided into ring segments by radial struts and/or walls 6.

The individual ring segment portions 7 of the housing or framework of the regenerative chamber 3 according to Figs. 2 and 3 can conveniently be provided at their shells 4 and 5 and also the radial struts and/or walls 6 with special mounting elements 8a, 8b, 8c, which each have flat supporting or abutment regions 9a; 9b', 9b", 9c', 9c", the dimensions of which are in each case adapted to the cross-section side lengths of at least an individual moulded element 1, as Fig. 3 shows.

The mounting parts 8a, 8b, 8c comprising the supporting or abutment surfaces 9a; 9b', 9b"; 9c', 9c" are in each case situated at least in the joint region between two stacks of moulded elements 1 arranged one above the other at the shells 4, 5 and the radial supporting struts and/or walls 6 of the regenerative chamber 3, as Fig. 3 shows particularly clearly.

Fig. 1 shows that each individual moulded element 1 forms a block 10 which is constructed as a one-piece extrusion moulded article and which is made from synthetic plastic material which not only has good heat transfer properties but also has very considerable resistance to the accretion of block-fouling particles such as soot, dust and/or salts.

It has been found particularly satisfactory in this respect if the individual blocks 10 are produced as extrusion moulded articles from a polyethersulfone synthetic plastic material such as is marketed for example under the Trade Name "Ultrason" by BASF.

The blocks 10 made from synthetic plastic material as integral extrusion moulded articles are shaped as hollow bodies which each have a plurality of throughflow ducts 13 which are situated adjacent to one another in the direction of their cross-section width 11 and their cross-section height 12, and which extend parallel to one another in the direction at right angles to the cross-section plane of the block 10 i.e. in the longitudinal direction 14 of the block 10, and are separated from one another in honeycomb manner by walls 15 and 16.

In the constructional example of a block 10 which is shown in Fig. 1, in each case eight throughflow ducts 13 are formed beside and behind one another in the direction of the cross-section width 11 and also in the direction of the cross-section height 12 respectively, so that the block 10 is provided with sixty-four throughflow ducts 13.

It has been found advantageous to have a polygonal shape for the blocks 10, the plan of the polygon being geometrically similar to the cross-section form of the individual throughflow ducts 13. Thus if the individual throughflow ducts 13 in the block have a square or rectangular cross-section, the block 10 itself should also have a square or rectangular plan.

But it is also possible to give some of or all of the blocks a trapezoidal or parallelogramshaped plan, in which case the throughflow ducts 13 are advantageously given a triangular cross-section.

In the constructional example which is shown in Fig. 1 of a block 10 produced as an integral extrusion moulded article it has been found satisfactory if the hydraulic diameter of the individual throughflow ducts 13 is in a ratio of between 1:0.2 and 1:0.3 approximately to the thickness of the walls 15 and 16 separating said ducts from one another in the block 10.

In actual practice the individual throughflow ducts 13 can be given for example a side length 17 or 18 of between 7 and 10 mm, whereas the walls 15 and 16 should be made with in each case a thickness 19 or 20 respectively of between 1.5 and 3 mm.

It has also been found satisfactory to use side lengths 11 and 12 for the blocks 10 at their cross-section plane of between 100 and 300 mm, and to select the length 14 of the blocks 10 in the direction at right angles to their basal planes as between 150 and 500 mm.

It is proposed to give the blocks 10 a length 14 which is in a ratio of between 10:1 and 50:1 to the hydraulic diameter of the ducts 13.

Another important construction criterion for the blocks 10 is that their cross-section boundary consists all round of plane walls 22 if each two walls situated opposite at the periphery are of the same length, which is the case when the plan is square, rectangular or parallelogram-shaped. But in the case of a traperoidal plan the mutually opposite walls which differ in side length can also be constructed with equidistant curvature, the wall with the greater side length being curved convexly and the wall with the relatively short length being curved concavely.

In many cases it may be found advantageous if the thickness of the boundary walls 22 of each block 10 always corresponds to approximately half the thickness of the walls 15 and 16 separating the throughflow ducts 13 from one another within the block 10. For then the same wall thicknesses are obtained in each case in the contact region between two neighbouring blocks 10 within the heat storage mass or the storage material 2 as within each individual block 10.

The arrangement of the moulded elements 1, or the block-form one-piece extrusion moulded articles 10 forming them, which is shown in Figs. 2 and 3 ensures in a simple way the accommodation of all the blocks 10 with their throughflow ducts 13 in a like-directed position in the housing and/or framework 4, 5, 6 of the regenerative chamber 3, and the blocks 10 stacked one behind the other in the longitudinal direction of the throughflow ducts 13 come into register with one another with their throughflow ducts 13.

Although the moulded elements 1 or blocks 10 which have been claimed and described above and illustrated in the drawings are suitable in a particularly advantageous way for forming the heat storage mass 2 or the storage material in annular-boundary stationary regenerative chambers 3 subdivided into ring segments, they may also readily be used for forming the heat storage mass 2 or the storage material in regenerative heat exchangers which operate with a rotating regenerative chamber. For in that case the relatively low construction weight of the blocks 10 manufactured as one-piece extrusion moulded articles from synthetic plastic material has particularly advantageous effects.

Figs. 4 and 5 show that-the individual ring segment portions 7 of the housing or framework of the regenerative chamber 3 can also be subdivided into a plurality of mutually adjacent compartments 7a and 7b which, then, each have substantially trapezoidal boundary walls. Blocks 10a and 10b having a suitable cross-sectional form can then be introduced into each of these compartments 7a and 7b, as Figs. 4 and 5 show clearly.

It is possible, on the one hand, to extrude the blocks 10a and 10b as dimensionally true moulded elements which each fit directly into the individual compartments 7a and 7b. But it is more advantageous if the blocks 1 0a and 10b are cut to size from a prefabricated extrusion moulded article in accordance with the various geometric forms and/or dimensions of the compartments 7a and 7b and they are then inserted into a sheet metal jacket 23a or 23b adapted to the outline of the respective compartment 7a or 7b. Instead of sheet metal jackets 23a and 23b it is also possible to use jackets made from another material, a laminate, preferably corrosion-resistant material.

As is indicated by thickly drawn lines in Fig.

5, it is also possible for the heat storage masses 2 in the individual compartments 7a, 7b of the regenerative chamber 3 of regenerative heat exchangers to be formed by having each filling of the compartments 7a and 7b composed of a plurality of blocks each of which, again, can be cut to size from a prefabricated extrusion moulded article. The filling in the left-hand compartment 7a shown in Fig.

5 consists for example of five blocks which differ in plan from one another and which are situated adjacent to one another. The filling of the right-hand compartment in Fig. 5 is formed e.g. of three blocks of different plan, whilst the filling of compartment 7b in Fig. 5 comprises two blocks which are alike but are in a mirror-image relationship to one another.

The individual blocks are held together by the sheet metal jacket 23a, 23b respectively, and with the help of the latter can be arranged interchangeably in the compartments 7a and 7b.

The moulded element 1 shown in Fig. 6 is produced as a block 10 with a trapezoidal plan as an extrusion moulded article from synthetic plastic material. It is indicated in this case that it can be moulded with throughflow ducts 13a, 13b, 13c which have differing opening or throughflow cross-sections. Thus the ducts 1 3a are made with a square opening or throughflow cross-section, whereas the throughflow ducts 13b have a substantially hexagonal throughflow cross-section, and the ducts 13c have an opening cross-section in the manner of a rectangular slot.

Since the block 10 has a trapezoidal plan it will be readily clear that either its walls bounding the inclined side surfaces are of a thickness varying from one of their ends to the other, or they are of a uniform thickness and the ducts 13a, 13b, 13c immediately adjacent to them are given a cross-section form differing to a greater or less degree from their usual form.

Claims

1. Regenerative heat-exchange element with a honeycomb of parallel throughflow ducts for the exchange media with walls defining the ducts, the element being formed as a one-piece extrustion moulded article.

2. Element according to claim 1, wherein each block is adapted, at least in its plan conformation, to the geometric shape and/or dimensions of compartments of the regenerative chamber of a rotary regenerative heat exchanger.

3. Element according to claim 1 or 2, wherein the hydraulic diameter of the throughflow ducts relative to the thickness of the' walls is in a ratio of approximately between 1:0.2 and 1:0.3.

4. Element according to claim 1, 2 or 3, wherein the element is of polygonal form the plan of which is geometrically similar to the cross-sectional form of individual throughflow ducts.

5. Element according to any one of the preceding claims, wherein individual throughflow ducts in the block have a square or rectangular cross-section, and the block has a square or rectangular plan.

6. Element according to any one of the preceding claims wherein the ducts have a length which is in a ratio of between about 10:1 and 50:1 relative to their hydraulic diameter.

7. Element according to any one of the preceding claims wherein the plan outer boundary of the element consists all round of plane walls.

8. Element according to any one of the preceding claims wherein the thickness of walls forming the outer boundary of the honeycombs are of about half the thickness of the walls which delimit the throughflow ducts from one another within the element.

9. Element according to any one of the preceding claims which is surrounded by a sheet metal jacket.

10. Element according to any one of the preceding claims which is cut to size from a prefabricated extrusion moulded article in accordance with the geometric form and/or dimensions of the compartments in the regenerative chamber in which it is to be used.

11. Element according to claim 1 substantially as herein described with reference to and as illustrated in the accompanying drawings.

12. Heat storage mass for fitting in the regenerative chamber of regenerative heat exchangers which inciudes a plurality of onepiece extrusion moulded articles made from synthetic plastic material and constructed as individual elements which are inserted, stacked side by side and one above the other, into a chamber housing and/or framework such that the elements all take up a same orientation in the chamber housing and/or framework and that those which are stacked above one another in the longitudinal direction of the throughflow ducts are aligned with their throughflow ducts in register with one another.

13. Heat storage mass according to claim 12 for annular-outline regenerative chambers having a chamber housing and/or framework subdivided in ring segment arrangement, the boundary surfaces of the individual, ring segment shaped, portions of the chamber housing and/or frame being provided with plane supporting or abutment regions the dimensions of which are in each case adapted to the crosssection side lengths of at least one individual element, and that these supporting or abutment regions are situated in each case at least in the region of the end portions of each element and/or in the joint region between two stacks of elements.

14. Heat storage mass for installation in the regenerative chamber of a regenerative heat exchanger, which is divided into a plurality of individual compartments, wherein the filling of at least some of the compartments is made up of a plurality of blocks which supplement one another to make up a cross-section corresponding to the compartment.

15. Heat storage mass substantially as herein described.

16. A rotary regenerative heat exchange including an element or heat storage mass according to any one of the preceding claims.