Heat exchange device based on high-temperature diffusion waste gas and diffusion system
By designing a heat exchange device based on high-temperature diffusion exhaust gas, using the process gas pipeline to exchange heat with the high-temperature diffusion exhaust gas in the cavity, and heating the process gas through heating devices, the temperature uneven problem caused by low-temperature diffusion exhaust gas in the prior art is solved, and the heat of high-temperature diffusion exhaust gas is not recovered, achieving efficient heat exchange and energy utilization.
Patent Information
- Application Number
- CN202421188302.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-28
- Publication Date
- 2025-02-28
- Estimated Expiration
- 2034-05-28
AI Technical Summary
In the existing diffusion process, low-temperature process gas enters the diffusion furnace and causes uneven temperatures, and the heat in the high-temperature diffusion waste gas is not effectively recycled, resulting in waste of energy.
A heat exchange device based on high-temperature diffusion exhaust gas is designed, including a device body, a process gas pipeline and a heating device. The device exchanges heat with the high-temperature diffused exhaust gas in the cavity through the process gas pipeline, and heats the process gas using heating devices to achieve the reuse of the high-temperature diffused exhaust gas.
It effectively avoids the condensation of high-temperature diffusion waste gas, improves the heat exchange effect, realizes the appropriate heating of process gas, increases the effective heat exchange area of high-temperature diffusion waste gas and process gas, and reduces energy waste.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application belongs to the field of photovoltaic cell technology, and specifically relates to a heat exchange device and a diffusion system based on high-temperature diffused exhaust gas. Background Art
[0002] In the photovoltaic industry, the improvement of processes and equipment must be based on the goal of "reducing costs and increasing efficiency". One of the core steps in preparing crystalline silicon cells is the diffusion process, which will affect the quality of the PN junction and thus the performance of the crystalline silicon cell.
[0003] The existing diffusion process usually introduces low-temperature process gas directly into the diffusion furnace for diffusion work. When a large amount of low-temperature process gas enters the diffusion furnace, it is easy to cause the local temperature in the diffusion furnace to drop sharply, making the temperature in the furnace uneven and reducing the uniformity of the square resistance between the battery cells. In addition, when the diffusion furnace is exhausted, the high-temperature exhaust gas will be directly cooled and post-processed. A large amount of heat in the high-temperature exhaust gas is not recycled, resulting in a large amount of energy waste, which does not meet the purpose of reducing costs and increasing efficiency. Utility Model Content
[0004] The present application aims to solve one of the technical problems in the related art at least to some extent.
[0005] In the first aspect of the present application, the present application proposes a heat exchange device based on high-temperature diffusion exhaust gas, comprising: a device body, the device body having a high-temperature exhaust gas inlet and a high-temperature exhaust gas outlet, the device body forming a cavity for accommodating high-temperature exhaust gas; a process gas pipeline, the process gas pipeline is located in the cavity, the process gas pipeline has a process gas inlet, a process gas outlet and a bending section located between the process gas inlet and the process gas outlet, the bending section is bent to form a space for accommodating process gas; a heating device, the heating device is located in the cavity. Thus, firstly, the process gas can be heated so that the process gas meets the process gas temperature requirements of the diffusion furnace, and the high-temperature diffusion exhaust gas can be reused; secondly, the high-temperature diffusion exhaust gas can be effectively prevented from being too low and condensed into solids attached to the heat exchange device, and the heat exchange effect of the heat exchange device is better; thirdly, the effective heat exchange area of the high-temperature diffusion exhaust gas and the process gas can be increased, so that the heat exchange device has a compact structure.
[0006] According to some embodiments of the present application, the invention further comprises: at least one baffle plate, the baffle plate being connected to the inner wall of the device body, the baffle plate having a high-temperature exhaust gas flow hole, and the baffle plate dividing the cavity into a plurality of sub-cavities. This is conducive to increasing the flow path and flow time of the high-temperature diffusion exhaust gas in the cavity, and effectively improving the heat exchange effect between the high-temperature diffusion exhaust gas and the process gas.
[0007] According to some embodiments of the present application, the heating device is provided in each sub-cavity, thereby enabling differential heating of high-temperature diffused exhaust gases in different sub-cavities and avoiding overall heating of the heat exchange device, which greatly increases the heat exchange cost.
[0008] According to some embodiments of the present application, each sub-cavity is provided with a first temperature detection element, and the first temperature detection element is used to detect the temperature of the high-temperature exhaust gas in the sub-cavity. Thus, differential detection of the high-temperature exhaust gas temperature in the sub-cavity can be achieved, which is conducive to differential heating of the high-temperature diffusion exhaust gas in different sub-cavities.
[0009] According to some embodiments of the present application, the heating device is located near the high-temperature exhaust gas flow hole, thereby facilitating sufficient heating of the relatively low-temperature high-temperature diffusion exhaust gas in the sub-cavity and preventing the high-temperature exhaust gas from being too cold and condensing into solids to block the high-temperature exhaust gas flow hole.
[0010] According to some embodiments of the present application, the first temperature detection element is located near the high-temperature exhaust gas flow hole, thereby achieving differential detection of the high-temperature exhaust gas temperature in the sub-cavities, and further achieving differential heating of the high-temperature diffused exhaust gas in different sub-cavities.
[0011] According to some embodiments of the present application, a second temperature detection element is provided near the process gas outlet, so that the temperature of the process gas after the heat exchange is completed can be detected, and the temperature of the heating device can be adjusted according to the detection data, which is conducive to ensuring that the process gas after the heat exchange meets the process gas temperature requirement of the diffusion furnace.
[0012] According to some embodiments of the present application, the device further includes: a control device, the control device being electrically connected to the first temperature detection element, the heating device, and the second temperature detection element, respectively. This is beneficial to improving the heat exchange effect between the high-temperature diffusion exhaust gas and the process gas.
[0013] According to some embodiments of the present application, the high-temperature exhaust gas and the process gas flow in a convection direction, which is beneficial to improving the heat exchange effect between the high-temperature diffusion exhaust gas and the process gas.
[0014] According to some embodiments of the present application, the high temperature exhaust gas inlet is located near the process gas outlet, and the high temperature exhaust gas outlet is located near the process gas inlet, thereby facilitating the improvement of the heat exchange effect between the high temperature diffusion exhaust gas and the process gas.
[0015] According to some embodiments of the present application, the bending section includes a spiral section, and the spiral section forms the space for accommodating the process gas, thereby increasing the effective heat exchange area between the high-temperature diffused exhaust gas and the process gas and further reducing the volume of the heat exchange device.
[0016] According to some embodiments of the present application, the device further comprises: a heat-insulating member, wherein the heat-insulating member wraps the device body, thereby effectively preventing the heat in the heat exchange device from being lost ineffectively.
[0017] In the second aspect of the present application, the present application proposes a diffusion system, the diffusion system includes the aforementioned heat exchange device and a diffusion furnace, the diffusion furnace is connected to the process gas outlet of the heat exchange device. As a result, the temperature of the process gas output through the process gas outlet of the heat exchange device is moderate, so that the temperature uniformity in the diffusion furnace is good, the diffusion effect of the diffusion system is good, which is conducive to improving the uniformity of the square resistance between battery cells and improving the qualified rate of battery products. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0019] Figure 1 It is a schematic diagram of a heat exchange device based on high-temperature diffused exhaust gas in some embodiments of the present application.
[0020] Reference numerals:
[0021] 100-device body; 110-high-temperature exhaust gas inlet; 120-high-temperature exhaust gas outlet; 130-cavity; 210-process gas inlet; 220-bending section; 230-process gas outlet; 300-heating device; 400-baffle; 410-high-temperature exhaust gas flow hole; 510-first temperature detection element; 520-second temperature detection element. DETAILED DESCRIPTION
[0022] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.
[0023] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.
[0024] In this application, unless otherwise clearly specified and limited, the terms such as "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.
[0025] Generally, the methods for heating process gas mainly include the following two types: first, preheating the process gas through an external heating device. The disadvantage is that the external heating device requires a large amount of additional energy to preheat the process gas, which will greatly increase the cost of preparing the battery; second, preheating the process gas through a heat exchange device. The thermal fluid in the heat exchange device is high-temperature diffusion exhaust gas. The disadvantage is that as the heat exchange process continues, the temperature of the high-temperature diffusion exhaust gas continues to decrease. If the temperature of the high-temperature diffusion exhaust gas is too low, it may condense into a solid and adhere to the heat exchange device, resulting in a significant reduction in the heat exchange effect of the heat exchange device. At the same time, using a heat exchange device to heat the process gas requires a large heat exchange area, but the space of the diffusion process is limited, and it is difficult to meet this condition.
[0026] Based on this, the present application proposes the following solution.
[0027] In the first aspect of the present application, the present application proposes a heat exchange device based on high temperature diffused exhaust gas, referring to Figure 1 , including: a device body 100, the device body 100 has a high-temperature exhaust gas inlet 110 and a high-temperature exhaust gas outlet 120, and the device body 100 forms a cavity 130 for accommodating high-temperature exhaust gas; a process gas pipeline, the process gas pipeline is located in the cavity 130, the process gas pipeline has a process gas inlet 210, a process gas outlet 230 and a bending section 220 located between the process gas inlet 210 and the process gas outlet 230, and the bending section 220 is bent to form a space for accommodating process gas; a heating device 300, the heating device 300 is located in the cavity 130. Thus, firstly, the process gas can be heated so that the process gas meets the process gas temperature requirements of the diffusion furnace, and the high-temperature diffusion exhaust gas can be reused; secondly, the diffusion exhaust gas can be effectively prevented from being too low in temperature and condensed into solid and attached to the heat exchange device, and the heat exchange effect of the heat exchange device is better; thirdly, the effective heat exchange area of the high-temperature diffusion exhaust gas and the process gas can be maximized, so that the heat exchange device has a compact structure.
[0028] The following is a detailed explanation of how the heat exchange device based on high-temperature diffused exhaust gas can achieve the above-mentioned effects:
[0029] In the heat exchange device of the present application, the process gas enters the process gas pipeline along the process gas inlet 210 and is output from the process gas pipeline along the process gas outlet 230. The high-temperature diffusion exhaust gas enters the cavity 130 along the high-temperature exhaust gas inlet 110 and is output from the cavity 130 along the high-temperature exhaust gas outlet 120. Since the process gas pipeline is located in the cavity 130, the high-temperature diffusion exhaust gas in the cavity 130 will exchange heat with the low-temperature process gas in the process gas pipeline, and the temperature of the high-temperature diffusion exhaust gas will decrease while the temperature of the low-temperature process gas will increase. In this way, the process gas can be heated to meet the process gas temperature requirements of the diffusion furnace, and the high-temperature diffusion exhaust gas can be reused.
[0030] As the heat exchange process continues, the temperature of the high-temperature diffusion waste gas continues to decrease. The heating device 300 located in the cavity 130 heats the high-temperature diffusion waste gas in the cavity 130, which can effectively prevent the diffusion waste gas from being too low in temperature. The high-temperature diffusion waste gas (such as phosphorus pentachloride, phosphorus pentoxide, metaphosphoric acid and other gases) condenses into solids and adheres to the heat exchange device, thereby preventing the heat exchange effect of the heat exchange device from being greatly reduced. As the heat exchange process continues, the temperature of the diffusion waste gas in the cavity 130 continues to decrease, which is not conducive to achieving effective heat exchange between the diffusion waste gas and the process gas, and may cause the process gas at the end of the heat exchange to be low, which is difficult to meet the process gas temperature requirements of the diffusion furnace. Heating the high-temperature diffusion waste gas in the cavity 130 by the heating device 300 is conducive to ensuring that the process gas at the end of the heat exchange meets the process gas temperature requirements of the diffusion furnace. In addition, by setting the heating device 300, the heat exchange device can be quickly heated up in a low temperature state (such as shutdown or maintenance), thereby improving the production efficiency of the diffusion process.
[0031] The process gas pipeline includes a bent section 220, and the bent section 220 is bent to form a space for accommodating the process gas, which increases the flow path and flow time of the process gas in the process gas pipeline, is beneficial to sufficient heat exchange between the high-temperature diffusion exhaust gas in the cavity 130 and the low-temperature process gas in the process gas pipeline, and is also beneficial to promoting mixing inside the process gas. Therefore, the effective heat exchange area of the high-temperature diffusion exhaust gas and the process gas can be maximized, so that the heat exchange device has a compact structure.
[0032] In the present application, the heat exchange device based on the high temperature diffusion exhaust gas can realize the heat transfer of two fluids at different temperatures, that is, part of the heat of the high temperature diffusion exhaust gas can be transferred to the low temperature process gas. The present application does not need to specifically limit the specific temperature range of high temperature and low temperature, as long as the temperature of the high temperature diffusion exhaust gas is greater than the temperature of the low temperature process gas.
[0033] In one embodiment, the high-temperature diffusion exhaust gas is the high-temperature exhaust gas output from a diffusion furnace.
[0034] In some embodiments, the material of the process gas pipeline is not particularly limited, and technical personnel in this field can choose it according to actual conditions, as long as the high-temperature diffused exhaust gas and process gas can have a good heat exchange effect, and the process gas pipeline material has a certain flexibility and can form a bending section 220.
[0035] In some embodiments, the heat exchange device based on high temperature diffused exhaust gas further includes: at least one baffle plate 400, referring to Figure 1 The baffle plate 400 is connected to the inner wall of the device body 100 , and the baffle plate 400 has a high-temperature exhaust gas flow hole 410 . The baffle plate 400 divides the cavity 130 into a plurality of sub-cavities.
[0036] As a specific example, the number of baffles 400 is n, the number of sub-cavities is n+1, and n is a positive integer. For example, when the number of baffles 400 is 1, the cavity 130 can be divided into 2 sub-cavities, when the number of baffles 400 is 2, the cavity 130 can be divided into 3 sub-cavities, and when the number of baffles 400 is 3, the cavity 130 can be divided into 4 sub-cavities. Preferably, the number of baffles 400 is 3-5.
[0037] The cavity 130 is divided into several sub-cavities by setting a deflection baffle 400, and each deflection baffle 400 has a high-temperature exhaust gas flow hole 410. When the high-temperature diffusion exhaust gas enters the cavity 130 along the high-temperature exhaust gas inlet 110, the high-temperature diffusion exhaust gas will flow in multiple sub-cavities through the high-temperature exhaust gas flow hole 410, and finally output the cavity 130 through the high-temperature exhaust gas outlet 120. This is conducive to extending the flow path and flow time of the high-temperature diffusion exhaust gas in the cavity 130, and effectively improving the heat exchange effect between the high-temperature diffusion exhaust gas and the process gas.
[0038] In some embodiments, a heating device 300 is provided in each sub-cavity. Figure 1 As the heat exchange process continues, the temperature of the high-temperature diffusion exhaust gas will gradually decrease. By arranging a heating device 300 in each sub-cavity, the high-temperature diffusion exhaust gas of different sub-cavities can be heated differentially. Therefore, it is possible to achieve differential heating of the high-temperature diffusion exhaust gas of different sub-cavities and avoid heating the heat exchange device as a whole, which greatly increases the heat exchange cost.
[0039] Furthermore, the heating device 300 is located near the high temperature exhaust gas flow hole 410, referring to Figure 1Since the high-temperature exhaust gas flow hole 410 is usually located at the end of the heat exchange area of the corresponding sub-cavity, the temperature near the high-temperature exhaust gas flow hole 410 is usually the lowest value of the high-temperature exhaust gas temperature in the sub-cavity. Therefore, arranging the heating device 300 near the high-temperature exhaust gas flow hole 410 is conducive to fully heating the high-temperature diffusion exhaust gas with a lower temperature in the sub-cavity, and is conducive to preventing the high-temperature exhaust gas from being too low in temperature and condensing into solid to block the high-temperature exhaust gas flow hole 410.
[0040] Furthermore, the specific type of the heating device 300 is not particularly limited, and those skilled in the art can select it according to actual conditions, as long as it can heat the high-temperature diffusion exhaust gas.
[0041] In some embodiments, each sub-cavity is provided with a first temperature detection element 510, referring to Figure 1 The first temperature detection element 510 is used to detect the temperature of the high-temperature exhaust gas in the sub-cavity. As the heat exchange process continues, the temperature of the high-temperature diffused exhaust gas will gradually decrease. By providing the first temperature detection element 510 in each sub-cavity, the high-temperature diffused exhaust gas in different sub-cavities can be differentially detected in temperature, thereby achieving differential detection of the high-temperature exhaust gas temperature in the sub-cavity, and then achieving differential heating of the high-temperature diffused exhaust gas in different sub-cavities.
[0042] Furthermore, the first temperature detection element 510 is located near the high temperature exhaust gas flow hole 410. Figure 1 Since the high-temperature exhaust gas flow hole 410 is usually located at the end of the heat exchange area of the sub-cavity, the temperature of the high-temperature diffused exhaust gas at the high-temperature exhaust gas flow hole 410 is usually the lowest value of the temperature of the high-temperature diffused exhaust gas in the sub-cavity. Therefore, the first temperature detection element 510 is arranged near the high-temperature exhaust gas flow hole 410, which is conducive to the accurate detection of the high-temperature diffused exhaust gas in the sub-cavity, and is conducive to the differential heating of the high-temperature diffused exhaust gas in the sub-cavity, thereby effectively preventing the high-temperature diffused exhaust gas from being too low in temperature and condensing into solid to block the high-temperature exhaust gas flow hole 410.
[0043] Further, the first temperature detection element 510 includes a thermocouple.
[0044] In some embodiments, a second temperature detection element 520 is disposed near the process gas outlet 230. Figure 1 .
[0045] Specifically, the second temperature detection element 520 is arranged near the process gas outlet 230, so as to detect the temperature of the process gas after the heat exchange is completed, and then adjust the temperature of the heating device 300 according to the detection data, which is conducive to better ensuring that the process gas after the heat exchange is completed meets the process gas temperature requirement of the diffusion furnace. For example, when the second temperature detection element 520 detects that the temperature of the process gas after the heat exchange is higher than the process gas temperature requirement of the diffusion furnace, the heating power of the heating device 300 can be reduced to achieve that the temperature of the process gas after the heat exchange is completed meets the process gas temperature requirement of the diffusion furnace; when the second temperature detection element 520 detects that the temperature of the process gas after the heat exchange is completed is lower than the process gas temperature requirement of the diffusion furnace, the heating power of the heating device 300 can be increased to achieve that the temperature of the process gas after the heat exchange is completed meets the process gas temperature requirement of the diffusion furnace.
[0046] Further, the second temperature detection element 520 includes a thermocouple.
[0047] In some embodiments, the heat exchange device based on high-temperature diffusion exhaust gas further includes: a control device, which is electrically connected to the first temperature detection element 510, the second temperature detection element 520, and the heating device 300. Thus, the control device can receive the detection electrical signal of the first temperature detection element 510, and the control device can adjust the heating device 300 according to actual conditions so that the temperature of the high-temperature diffusion exhaust gas in the sub-chamber is within a suitable range; the control device can receive the detection electrical signal of the second temperature detection element 520, and the control device can adjust the heating device 300 according to actual conditions so that the temperature of the process gas after the heat exchange ends meets the process gas temperature requirement of the diffusion furnace.
[0048] Furthermore, the control device includes conventional control devices such as computers and mobile phones, wherein the manner in which the control device is electrically connected to the first temperature detection element 510, the second temperature detection element 520, and the heating device 300 are all conventional means and will not be repeated here.
[0049] In some embodiments, the flow direction of the high-temperature exhaust gas and the process gas is convection, thereby effectively improving the heat exchange effect of the high-temperature diffusion exhaust gas and the process gas.
[0050] In some embodiments, the high temperature exhaust gas inlet 110 is located near the process gas outlet 230, and the high temperature exhaust gas outlet 120 is located near the process gas inlet 210. Figure 1 This is beneficial to improving the heat exchange effect between the high-temperature diffused exhaust gas and the process gas.
[0051] In some embodiments, the bend section 220 includes a spiral section, referring to Figure 1The spiral section forms a space for accommodating the process gas, thereby increasing the effective heat exchange area between the high-temperature diffused exhaust gas and the process gas and further reducing the volume of the heat exchange device.
[0052] In some embodiments, the heat exchange device based on high-temperature diffused exhaust gas further includes: a heat-insulating member, which wraps the device body 100. Thus, the heat in the heat exchange device can be effectively prevented from being lost ineffectively.
[0053] In the second aspect of the present application, the present application proposes a diffusion system, which includes the aforementioned heat exchange device and a diffusion furnace, and the diffusion furnace is connected to the process gas outlet 230 of the heat exchange device. As a result, the temperature of the process gas output through the process gas outlet 230 of the heat exchange device is moderate, so that the temperature uniformity in the diffusion furnace is good, the diffusion effect of the diffusion system is good, which is conducive to improving the uniformity of the square resistance between battery cells and improving the qualified rate of battery products.
[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.
Claims
1. A heat exchange device based on high-temperature diffused exhaust gas, characterized in that: include: A device body, wherein the device body has a high-temperature exhaust gas inlet and a high-temperature exhaust gas outlet, and the device body forms a cavity for accommodating the high-temperature exhaust gas; a process gas pipeline, the process gas pipeline being located in the cavity, the process gas pipeline having a process gas inlet, a process gas outlet, and a bending section located between the process gas inlet and the process gas outlet, the bending section being bent to form a space for accommodating the process gas; A heating device is located in the cavity.
2. The heat exchange device according to claim 1, characterized in that: Also includes: At least one baffle is connected to the inner wall of the device body, the baffle has a high-temperature exhaust gas flow hole, and the baffle divides the cavity into a plurality of sub-cavities.
3. The heat exchange device according to claim 2, characterized in that: The heating device is arranged in each of the sub-cavities; And / or, each of the sub-cavities is provided with a first temperature detection element, and the first temperature detection element is used to detect the temperature of the high-temperature exhaust gas in the sub-cavity.
4. The heat exchange device according to claim 3, characterized in that: The heating device is located near the high-temperature exhaust gas flow hole; And / or, the first temperature detection element is located near the high-temperature exhaust gas flow hole.
5. The heat exchange device according to claim 3 or 4, characterized in that: A second temperature detection element is provided near the process gas outlet.
6. The heat exchange device according to claim 5, characterized in that: Also includes: A control device is electrically connected to the first temperature detection element, the heating device, and the second temperature detection element respectively.
7. The heat exchange device according to any one of claims 1 to 3, characterized in that: The high-temperature exhaust gas and the process gas flow in a convection direction.
8. The heat exchange device according to claim 6, characterized in that: The high-temperature exhaust gas inlet is located near the process gas outlet, and the high-temperature exhaust gas outlet is located near the process gas inlet.
9. The heat exchange device according to any one of claims 1 to 3, characterized in that: The bending section includes a spiral section, and the spiral section forms the space for accommodating the process gas; And / or, further comprising: a heat-insulating component, wherein the heat-insulating component wraps the device body.
10. A diffusion system, characterized in that: include: The heat exchange device and diffusion furnace according to any one of claims 1 to 9, wherein the diffusion furnace is connected to the process gas outlet of the heat exchange device.