Patent Application
20190310023
The present disclosure relates to a removable plate heat exchanger, and more specifically relates to a multi-pass removable plate heat exchanger without a need of installing connections to a mobile pressure plate side, and a dedicated heat transfer plate therefor.
A plate and frame heat exchanger is generally referred to as a plate heat exchanger (PHE), which was originated from the European food industry over 60 years ago, when there was a demand for a heat exchanger that was efficient, energy-saving, structurally compact, easy to clean, and adaptable to change of design conditions. PHEs could satisfy such initial requirements. Currently, those basic requirements are still present, and the PHEs have been widely used in various industrial fields throughout the world, e.g., refrigerating, heating and ventilation, air-conditioning, and oil cooling. Due to its characteristics such as high heat transfer efficiency, low heat loss, light-weighted and compact structure, less space demand, ease of assembly and cleaning, wide range of operating parameters, and long service life, etc., the plate heat exchanger is an ideal device for liquid-to-liquid and liquid-to-gas heat exchange. Under a same pressure loss, the plate heat exchanger has a heat transfer coefficient 3 to 5 times higher than that of a tubular heat exchanger, but with only a fraction of space requirement; besides, the heat recovery rate of the plate heat exchanger may amount to 90% above. Common plate heat exchangers available in the market are formed by stacking a series of metal sheets with certain corrugated patterns.
Variations of plate heat exchangers mainly include removable (frame) types and brazed/welded types. Profiles of heat transfer plate mainly include herringbone corrugated patterns, horizontally corrugated patterns, and dimpled patterns. The removable plate heat exchanger is the most commonly used compact heat exchanger type for heating, cooling or heat recovery in various industrial fields. The popularity of this type of exchanger is attributed to its various unique and advantageous properties, including a high heat transfer efficiency, a modular structure, ease of assembly and disassembly, convenience for cleaning and maintenance, and a high degree of flexibility in its sizing and configuration to match a particular application duty. A plate pack of a typical removable plate heat exchanger comprises a series of sequentially assembled metal sheets, where an elastic sealing gasket is installed between every two metal sheets to thereby form a hot fluid flow channel and a cold fluid flow channel that are mutually alternating and isolated. Sealing gaskets are mounted to seal corner ports and the periphery of heat transfer plates to prevent mixing of the cold and hot fluids as well as leakage of any fluid through the periphery to the ambient. The plate pack is tightly compressed by a frame system to provide pressure bearing and sealing capabilities. The frame system comprises mainly: a front fixed pressure plate, a rear mobile pressure plate, a top carrying beam, and clamp bolts distributed around. During the assembly process, the clamp bolts are tightened to an appropriate pressure degree to secure all flow channels free from leakage, without crushing the heat transfer plates. Connections of different types and shapes are provided on the fixed pressure plate and/or the mobile pressure plate to allow the cold and hot fluid mediums to enter and exit the heat exchanger.
As shown in
As an important component of the plate heat exchanger, the plate pack significantly influences the overall performance and working condition of the plate heat exchanger. Therefore, the heat transfer and the circulation characteristic of the removable plate heat exchanger may be adjusted and optimized by changing the following parameters: 1) geometric profiles of the heat transfer plate; 2) dimension (width and length) of the heat transfer plate; 3) dimension of the corner ports; 4) number of plates; and 5) respective numbers of flow passes for the cold and hot flow channels. It needs to be particularly noted that the flow pass and the flow channel in the art are two technical terms associated with each other but having different meanings. The flow pass refers to a group of parallel channels where any given medium flows in the same direction, while the flow channel refers to a medium flow channel formed by two adjacent sheets inside the plate heat exchanger. Generally, a plurality of flow channels are connected in parallel or in series to form different combinations of cold and hot medium channels. Based on the definitions above, it is seen that
To satisfy a heat transfer duty that requires an extremely high heat recovery efficiency at a very small temperature difference, a heat transfer plate with a relatively high aspect ratio is needed. However, a maximum length of the heat transfer plate is limited to a feasible aspect ratio, because if the heat transfer plate has too high an aspect ratio, the heat exchanger becomes unstable in structure and spatially less optimized for installation; therefore, the height of the heat transfer plate is more frequently limited by the available height for installing the device. This limitation may be alleviated by designing a multi-pass heat exchanger, such that the cold and hot fluids are turned into opposite directions by a stopper plate in each flow channel. Theoretically, varying the number of flow passes may satisfy the need of any efficient heat transfer duty; multi-pass design is required particularly for industrial applications with a low flow rate or a close approach temperature.
In a conventional multi-pass heat exchanger, the plate pack is divided into a plurality of sections between the fixed pressure plate and the mobile pressure plate. A stopper plate 6 is mounted between two adjacent sections to force a fluid to change its flow direction between passes. The stopper plate 6 differs from a regular heat transfer plate 3 in that two corner ports of the stopper plate 6 are blocked. Despite of the many advantages, conventional multi-pass designs have a number of problems and inconveniences in practical applications. As shown in
Further, as shown in
To solve various problems existing in the prior art, and particularly to overcome the technical limitations in the prior art that connections need to be arranged at two opposite ends of a heat exchanger with a multi-pass design, the present disclosure provides a novel structure and design of a multi-pass heat transfer plate, which allows for more efficient and easier maintenance process, by allowing multi-pass removable plate heat exchanger without the need of arranging connections on a mobile pressure plate.
To address some performance drawbacks and operational inconvenience in use of a conventional multi-pass plate heat exchanger described above, the present disclosure further provides a novel heat transfer plate construction, which has an equivalent or better heat transfer performance compared with a traditional multi-pass plate, but without key drawbacks of the traditional multi-pass plate heat exchanger.
Specifically, the present disclosure provides a heat transfer plate for a multi-pass removable plate heat exchanger. The heat transfer plate has a plurality of lateral partitions, where a plurality of mutually communicative lateral-pass partitions or mutually isolated longitudinal pass partitions may be formed by specially shaped gaskets. With this novel type of heat transfer plates, a multi-pass removable plate heat exchanger without a need of arranging connections at the mobile pressure plate may be constructed. The present disclosure further provides a specially shaped and constructed gasket to implement a multi-pass removable plate heat exchanger without a need of arranging connections at the mobile pressure plate.
According to one of the technical solutions of the present disclosure, a multi-pass removable plate heat exchanger can be implemented, which comprises: a fixed pressure plate, a mobile pressure plate, and a plate pack sandwiched between the fixed pressure plate and the mobile pressure plate via clamp bolts. The plate pack further comprises a plurality of lateral-pass plates configured with specially shaped sealing gaskets to form two or more successively communicating lateral partitions. The lateral-pass plates are assembled to form the plate pack with mutually alternating cold and heat fluid flow channels, the number of passes on the multi-pass removable plate heat exchanger being equal to the number of lateral partitions on each lateral-pass plate.
Preferably, in the multi-pass removable plate heat exchanger according to the technical solution above, connections are only arranged on the fixed pressure plate, without a need of arranging connections on the mobile pressure plate.
Preferably, in the multi-pass removable plate heat exchanger according to the technical solution above, the lateral-pass plate may typically have two, three, or four lateral partitions.
According to another technical solution of the present disclosure, a multi-pass removable plate heat exchanger can be implemented, which comprises: a fixed pressure plate, a mobile pressure plate, and a plate pack sandwiched between the fixed pressure plate and the mobile pressure plate via clamp bolts. The plate pack further comprises one section of two-zone lateral-pass plates, and (N−1) sections of two-zone lateral-partition plates. Each two-zone lateral-pass plate is configured with specially shaped sealing gaskets to form two mutually communicating lateral partitions. Each two-zone lateral-partition plate is configured with specially shaped sealing gasket to form two mutually isolated lateral partitions. The section of two-zone lateral-pass plates is allocated immediately adjacent to the mobile pressure plate to force both hot fluid and cold fluids to make a U-turn, while (N−1) sections of two-zone lateral-partition plates are arranged adjacent to the fixed pressure plate. The thus assembled plate pack creates mutually alternating cold and heat fluid flow channels, where each fluid enters the heat exchanger via the fixed pressure plate, flows towards the mobile pressure plate along one side of the partition, makes a U-turn upon reaching the mobile pressure plate, and then flows back along the other side of the partition, and lastly exits the heat exchanger via the fixed pressure plate. The total number of passes achieved in this novel type of the multi-pass removable plate heat exchanger is equal to 2N, where N is a natural number greater than or equal to 2.
Preferably, in the multi-pass removable plate heat exchanger according to the technical solution above, connections are only arranged on the fixed pressure plate, without a need of arranging connections on the mobile pressure plate.
Preferably, in the multi-pass removable plate heat exchanger according to the technical solution above, the sections with lateral-pass plates are allocated immediately adjacent to the mobile pressure plate, and while the remaining sections of lateral-partition plates are allocated adjacent to fixed pressure plate to achieve the remaining flow passes.
According to a further technical solution of the present disclosure, a lateral-pass plate specific for the novel type of multi-pass removable plate heat exchanger is provided, wherein the heat transfer plate is a lateral-pass plate, wherein flat groove patterns are provided at the periphery and in the interior of the lateral-pass plate for configuring sealing gaskets to thereby form two or more successively communicative lateral partitions.
According to a further technical solution of the present disclosure, a lateral-partition plate specific for the novel type of multi-pass removable plate heat exchanger is provided, wherein the heat transfer plate is a lateral-partition plate, wherein flat groove patterns are provided at the periphery and in the interior of the lateral-partition plate for configuring sealing gaskets to thereby form two or more mutually isolated lateral partitions
Preferably, in the heat transfer plate specific for the novel type of multi-pass removable plate heat exchanger according to the technical solution above, the heat transfer plate may possess different thermal-hydraulic performance characteristics through variations in geometrical profiles, wherein heat transfer plates with different geometrical profiles may also be arranged in a hybrid fashion within the same plate pack to form a mixed plate pack.
Preferably, in the heat transfer plate specific for the novel type of multi-pass removable plate heat exchanger according to the technical solution above, the geometrical profile variations may include, but not limited to chevron corrugation angles, circular or irregular dimples, studs, or other structures with the effect of enhancing heat transfer efficiency.
Preferably, in the heat transfer plates specific for the novel type of multi-pass removable plate heat exchanger according to the technical solution above, sealing and/or partitioning functionalities of the sealing gaskets may be partially or completely replaced by other seal structures or mechanisms.
Preferably, in the heat transfer plate specific for the novel type of multi-pass removable plate heat exchanger according to the technical solution above, the other seal structures or mechanisms may include, but not limited to brazing, welding, diffusion bounding or mechanical contact sealing.
According to a further technical solution of the present disclosure, a sealing gasket specific for the lateral-pass plate is provided, wherein the sealing gasket is situated inside flat grooves provided at the periphery and in the interior of the lateral-pass plate, such that the lateral-pass plate is formed with two or more lateral partitions that are successively in communication.
According to a further technical solution of the present disclosure, a sealing gasket specific for the lateral-partition plate is provided, wherein the sealing gasket is situated within flat grooves provided at the periphery and in the interior of the lateral-partition plate, such that the lateral-partition plate is formed with two or more lateral partitions that are mutually isolated.
Compared with conventional single-pass designs and conventional multi-pass designs, the multi-pass removable plate heat exchanger (PHE) constructed according to the present disclosure has the following advantages:
Improved maintainability: because no connections are arranged at the mobile pressure plate side, the multi-pass heat exchanger according to the present disclosure may be easily disassembled for cleaning and repair like a conventional single-pass heat exchanger;
Increased effective heat transfer area: because i) with fewer corner ports in lateral-pass plate, the percentage of non-heat transfer area is reduced; ii) with decreased peripheral length of the heat transfer plates, heat loss through the external area in direct contact with the ambient is reduced; iii) internal gasket grooves can be made very narrow, which reduces loss in effective heat exchange areas;
Improved overall heat transfer efficiency: With lateral-pass plates, multiple pass heat exchanger can be formed without occurrence of local co-currency between each neighboring pass as present in conventional multi-pass designs, and the overall heat transfer efficiency of the heat exchanger is improved;
Reduced flow pressure drop: because the turn of flow direction on a lateral-pass plate is relatively gentle and the fluid velocities are substantially constant during each lateral turn, there is no apparent compression and expansion in distribution areas, and the additional pressure drop due to directional turn associated with multiple passes is smaller;
Reduced heat loss from the ambiance: because the interface area with the ambient for the same heat transfer area is reduced, the heat loss of the entire heat exchanger is reduced;
More compact structure: due to the small aspect ratio of each heat transfer plate, the overall shape of the heat exchanger tends to be cubic, such that the space requirement for the same amount of total heat transfer area can be substantially reduced;
Overall more efficient heat exchanger: due to various advantages above, a multi-pass heat exchanger that is thermally more efficient and easier-to-maintain may be constructed according to the present disclosure, thereby satisfying the demand of more efficient and more easy-to-service heat exchangers in a wide range of applications such as energy recovery, process isolation, and pressure breaker, etc.
The features, working principles, and other advantages of the present disclosure will become apparent through further illustration in conjunction with the accompanying drawings.
Hereinafter, the present disclosure will be described through examples with reference to the accompanying drawings, wherein:
Hereinafter, the technical contents, structural features, and achieved technical objects and effects of the preferred embodiments of the present disclosure will be illustrated in detail with reference to the accompanying drawings.
The present disclosure overcomes the following technical bias regarding a multi-pass plate heat exchanger: the multi-pass plate heat exchanger needs to arrange inlet and outlet interfaces for cold and hot fluids, as well as the connections therefor, at two opposite sides of the fixed pressure plate and mobile pressure plate of a heat exchanger. This technical bias is extensively seen in prior technical literatures describing multi-pass heat exchangers, but the Inventor of the present disclosure fundamentally overthrows this technical bias through innovative technical solutions. A heat transfer plate for a multi-pass removable plate heat exchanger according to the present disclosure has a plurality of lateral partitions, which, in combination with specially shaped gaskets, may form a plurality of communicative flow channels or mutually isolated flow channels. In contrast with the dedicated heat transfer plate of the present disclosure, the heat transfer plate in the prior art does not have a plurality of mutually communicative or isolated lateral partitions, which is an integral zone for circulating cold and hot fluids.
According to a preferred embodiment of the present disclosure, a key component for solving the technical problem of a conventional multi-pass plate heat exchanger is a heat transfer plate having a plurality of lateral partitions. These lateral partitions are further fitted with specially shaped sealing gaskets, such that a plurality of mutually communicative lateral-pass flow channels may be implemented between two adjacent plates, and such a special heat transfer plate may be referred to as a lateral-pass plate. Further, with the lateral-pass plate of the present disclosure, a multi-pass plate heat exchanger without a need of arranging connections on the mobile pressure plate may be built, the number of its passes corresponding to the number of lateral partitions on each lateral-pass plate. The working principle of the lateral-pass plate of the present disclosure is described below.
The pass for the cold side fluid as shown in
The lateral-pass plate having two lateral partitions according to the present disclosure may be easily extended to other multi-pass arrangements, e.g., theoretically, the number of lateral partitions of each lateral-pass plate may be increased to 3 or 4 or higher dependent on operating duties. In actual industrial applications, a lateral-pass plate having two to four lateral partitions is possibly the most practical and most economical.
As mentioned above, because the number of passes of the multi-pass heat exchanger that only uses lateral-pass plates corresponds to exactly the number of lateral partitions on each lateral-pass plate, it may be understood that the number of passes of the plate heat exchanger manufactured according to the above embodiments of the present disclosure increases in a lateral direction. Although the number of passes may arbitrarily increase to any number in the lateral direction theoretically, the lateral-pass plate with 2, 3, or 4 lateral-pass partitions is likely most practical and economical due to unfavorable dimension increase in horizontal direction at higher pass numbers; in other words, the number of passes of the plate heat exchanger employing lateral-pass plates is preferably 2 to 4. In view of the above, the Inventor of the present disclosure further provides an alternative embodiment based on a combined implementation of lateral-pass plates and lateral-partition plates, such that the number of passes of the multi-pass plate heat exchanger manufactured by the present disclosure may increase without limitation. Hereinafter, this alternative embodiment of the present disclosure will be specifically described.
By using the two-zone lateral-pass plate shown in
As shown in
Based on operating parameters and the required number of passes, the heat transfer plate described by the present disclosure has the following two typical application examples. The heat transfer plate required by the two application examples may be provided by a same plate pressing die, except for the number of corner ports needed to be cut, and the shapes and configurations of sealing gaskets.
In the first application example, there are only lateral passes without longitudinal passes. In other words, only lateral-pass heat transfer plates are used, while partition heat transfer plate is not used. Although the number of lateral passes is not limited theoretically according to the principle of the present disclosure, the present application example is more suitable for implementing a multi-pass removable plate heat exchanger with 2, 3, or 4 passes in actual applications due to consideration of unfavorable dimension increase in horizontal direction.
In the second application example, not only the lateral passes but also the longitudinal passes are employed; in other words, lateral-pass heat transfer plates and partition heat transfer plates are used in combination. A second application example of the present disclosure is suitable for circumstances requiring a higher number of passes, including 4, 6, 8, 10, . . . 2N (any even number) passes (the number of passes achievable for the entire heat exchanger can be viewed as any number, without being limited to even number only, if each heat transfer plate is used as the reference.). In this application example, there is no structural limitation on the maximum number of passes.
In the first application example and the second application example, the lateral-pass plate for a multi-pass removable plate heat exchanger is provided with flat grooves at the periphery and in the interior to allow sealing gaskets to form mutually communicative two or more lateral partitions; while the lateral-partition plate for the multi-pass removable plate heat exchanger is provided with flat grooves at the periphery and in the interior to allow the sealing gaskets to form two mutually isolated partitions.
Besides, in the actual applications, the heat transfer plate pattern or corrugation may be customized and optimized according to actual needs of the heat exchange circumstances; for a scenario of large flow rates with small allowable pressure drops, a plate profile with a small pressure resistance should be selected; otherwise, a plate model with a large pressure resistance is selected. Additionally, when selecting suitable plates, those with too small a single-plate area should not be selected; otherwise, too many plates will be needed, and consequently the inter-plate fluid velocity would be too small, and the heat transfer coefficient would be too low; this issue should be particularly addressed for large heat exchangers. Specifically, the heat transfer plate for the multi-pass removable plate heat exchanger may possess different thermal performances through variations in geometrical profiles, wherein the heat transfer plates with different geometrical profiles may be combined within the same plate pack in a hybrid fashion. Variations in plate geometrical profiles may include employing different chevron corrugation angles, circular or irregular dimple, studs, or other structures for enhancing heat transfer coefficient. Additionally, for the heat transfer plate in the multi-pass removable plate heat exchanger according to the present disclosure, sealing and partitioning functionalities of the sealing gaskets may be partially or completely replaced by other seal structures or mechanisms, which may include, but not limited to, brazing, welding, diffusion bounding or mechanical contact sealing.
In the application examples of the present disclosure, illustration will be made with a single-wall PHE as an example. In heat exchange scenarios, which require absolute prevention of mixing of two media (e.g., household water application), a double-wall PHE is mostly adopted so as to effectively prevent leakage and mixing of fluids. To those skilled in the art, the pass structures and designs of the lateral-pass plate and lateral-partition plate as disclosed in the present disclosure may also be directly applied to the double-wall PHE.
What have been disclosed above are only preferred embodiments of the present disclosure, which, of course, cannot serve as a basis for limiting the scope of the present disclosure. Therefore, similar, extended or equivalent embodiments using the same principles still fall within the scope covered by the present disclosure. It should be understood that the descriptions given above are intended for illustration only, not for limitation. For example, the embodiments (and/or aspects thereof) may be combined in use; an ideal number of passes of the lateral-pass plate might be greater than 4 in some industrial applications. In addition, various alterations may be made based on the teachings of the present disclosure so as to be adapted to specific circumstances or materials without departing from the scope of the present disclosure. Through reading the descriptions above, many other embodiments and alternations within the scope and spirit of the claims are obvious to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201610607994.2 | Jul 2016 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2017/093650 | 7/20/2017 | WO | 00 |
