Flash blackwater heat recovery device

Abstract

The present disclosure relates to a flash blackwater waste heat recovery device, comprising a heat exchanger, a control valve and a heating water pipe, wherein the heat exchanger has a first pipe and a second pipe arranged in a mutual heat exchange manner; the control valve is arranged between a high-temperature blackwater pipe from a flash tank, a low-temperature blackwater drain pipe after heat exchange, a first port and a second port of the first pipe, and is configured to switch the forward flow or reverse flow of the blackwater in the first pipe; in the forward flow mode, the control valve controls the first port of the first pipe to be connected with the high-temperature blackwater pipe, and the second port of the first pipe to be connected with the low-temperature blackwater drain pipe; in the reverse flow mode, the control valve controls the second port of the first pipe to be connected with the high-temperature blackwater pipe, and the first port of the first pipe to be connected with the low-temperature blackwater drain pipe; and the heating water pipe is communicated with the second pipe to form a loop.

Description

Technical Field

[0001] This disclosure relates to the field of waste heat recovery technology, and in particular to a flash black water waste heat recovery device. Background Technology

[0002] In the coal chemical production sector, recovering industrial waste heat is a key direction for improving industrial energy efficiency and reducing carbon emissions. Currently, many companies have proposed using the high-temperature black water from flash evaporation as a heat source to provide heat for heating equipment. However, flash evaporation black water has a high solids content, making pipelines prone to blockage. When blockage occurs, not only is waste heat recovery impossible, but inspection and repair are also required, which is time-consuming and labor-intensive.

[0003] Therefore, how to prevent pipeline blockage during the recovery of waste heat from flash evaporation black water is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a flash black water waste heat recovery device.

[0005] The flash black water waste heat recovery device disclosed herein includes: A heat exchanger having a first conduit and a second conduit arranged for mutual heat exchange: A control valve is disposed between a high-temperature black water pipeline from a flash tank, a low-temperature black water drainage pipeline cooled after heat exchange, and a first port and a second port of the first pipeline. The control valve is configured to switch the black water to flow forward or backward in the first pipeline. In forward flow mode, the control valve controls the first port of the first pipeline to be connected to the high-temperature black water pipeline, and the second port of the first pipeline to be connected to the low-temperature black water drainage pipeline. In reverse flow mode, the control valve controls the second port of the first pipeline to be connected to the high-temperature black water pipeline, and the first port of the first pipeline to be connected to the low-temperature black water drainage pipeline. Heating water pipe, which is connected to the second pipeline to form a loop.

[0006] In one embodiment of this disclosure, a first pressure detection element is provided on the high-temperature black water pipeline, and a second pressure detection element is provided on the low-temperature black water drainage pipeline. The control valve is further configured to control the black water to switch from forward flow to reverse flow in the first pipeline when the pressure difference between the first pressure detection element and the second pressure detection element reaches a preset pressure value.

[0007] In one embodiment of this disclosure, the preset pressure value is 0.08-0.15 MPa.

[0008] In one embodiment of this disclosure, the control valve is further configured to control the black water in the first pipeline to switch from forward flow to reverse flow when the black water in the first pipeline flows forward for a first preset time, and to control the black water in the first pipeline to switch from reverse flow to forward flow when the black water in the first pipeline flows in reverse for a second preset time, wherein the second preset time is greater than the first preset time.

[0009] In one embodiment of this disclosure, the second preset time is twice the first preset time.

[0010] In one embodiment of this disclosure, the first pipeline and the second pipeline include spiral pipeline segments, and the spiral pipeline segments of the first pipeline and the second pipeline are wound together.

[0011] In one embodiment of this disclosure, the high-temperature black water pipeline is connected to the high-pressure flash tank, and the low-temperature black water drainage pipeline is connected to the low-pressure flash tank.

[0012] In one embodiment of this disclosure, a first channel and a second channel are connected in parallel to the first port of the first pipeline, and a third channel and a fourth channel are connected in parallel to the second port of the first pipeline. The first channel and the fourth channel are configured to communicate with the high-temperature black water pipeline, and the second channel and the third channel are configured to communicate with the low-temperature black water drainage pipeline. The control valve includes a first switching valve disposed in the first channel, a second switching valve disposed in the second channel, a third switching valve disposed in the third channel, and a fourth switching valve disposed in the fourth channel. When the first and third switching valves are open, and the second and fourth switching valves are closed, black water flows forward in the first pipeline. When the second and fourth switching valves are open and the first and third switching valves are closed, the black water flows in reverse within the first pipeline.

[0013] In one embodiment of this disclosure, the first switching valve, the second switching valve, the third switching valve, and the fourth switching valve are all hemispherical valves.

[0014] In one embodiment of this disclosure, the control valve is a two-position four-way valve, the first valve port of the two-position four-way valve is connected to the high-temperature black water pipeline, the second valve port of the two-position four-way valve is connected to the low-temperature black water drainage pipeline, the third valve port of the two-position four-way valve is connected to the first port of the first pipeline, and the fourth valve port of the two-position four-way valve is connected to the second port of the first pipeline. When the two-position four-way valve is in the first working position, the first and third valve ports of the two-position four-way valve are connected, the second and fourth valve ports of the two-position four-way valve are connected, and the black water flows in the first pipeline in the forward direction. When the two-position four-way valve is in the second working position, the second and third valve ports of the two-position four-way valve are connected, and the first and fourth valve ports of the two-position four-way valve are connected, and the black water flows in reverse in the first pipeline.

[0015] One beneficial effect of the flash evaporation black water waste heat recovery device disclosed herein is that the control valve switches the black water flow from forward to reverse in the first pipeline, changing the velocity distribution of the black water within the first pipeline. This allows the black water to flush through the low-velocity region of the forward flow, carrying away settled solid particles and preventing blockage in the first pipeline. The control valve also improves the heat exchange efficiency between the first and second pipelines. Therefore, the flash evaporation black water waste heat recovery device of this disclosure achieves efficient waste heat recovery while preventing black water blockage in the pipeline. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the present disclosure and, together with their description, serve to explain the principles of the present disclosure.

[0017] Figure 1 This is a schematic diagram of the structure of a flash black water waste heat recovery device provided in one embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of a flash black water waste heat recovery device provided in another embodiment of this disclosure.

[0018] Figure 1 and Figure 2 The one-to-one correspondence between the component names and the reference numerals in the figures is as follows: 1-First pipeline; 2-Second pipeline; 3-High-temperature black water pipeline; 4-Low-temperature black water drainage pipeline; 5-Heating water pipe; 6-First pressure detection element; 7-Second pressure detection element; 8-High-pressure flash tank; 9-Low-pressure flash tank; 10-First switching valve; 11-Second switching valve; 12-Third switching valve; 13-Fourth switching valve; 14-Two-position four-way valve; 141-First valve port; 142-Second valve port; 143-Third valve port; 144-Fourth valve port. Detailed Implementation

[0019] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0020] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use.

[0021] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0022] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0024] In this article, terms such as "up," "down," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, rather than to define the absolute position of these related parts.

[0025] In this article, "first," "second," etc., are used only to distinguish one another, and not to indicate degree of importance, order, or prerequisite for each other.

[0026] In this document, terms such as “equal” and “same” are not strict mathematical and / or geometric limitations, but also include errors that are understandable to those skilled in the art and permissible in manufacturing or use.

[0027] While existing flash water waste heat recovery devices can recover waste heat, the high solid content of the flash black water means that blockages not only prevent heat recovery but also necessitate time-consuming and labor-intensive inspection and repair. Therefore, this disclosure provides a flash water waste heat recovery device. For ease of understanding, please refer to the following... Figure 1 , Figure 2 The specific structure and working principle of the flash water waste heat recovery device disclosed herein will be described in detail with reference to the embodiments.

[0028] The flash black water waste heat recovery device disclosed herein includes a heat exchanger, a control valve, and a heating water pipe 5. The heat exchanger has a first pipe 1 and a second pipe 2 arranged in a mutual heat exchange manner. The control valve is located between the high-temperature black water pipe 3 from the flash tank, the low-temperature black water drainage pipe 4 cooled after heat exchange, and the first and second ports of the first pipe 1. The control valve is configured to switch the black water to flow forward or backward in the first pipe 1. In the forward flow mode, the control valve controls the first port of the first pipe 1 to be connected to the high-temperature black water pipe 3, and the second port of the first pipe 1 to be connected to the low-temperature black water drainage pipe 4. In the reverse flow mode, the control valve controls the second port of the first pipe 1 to be connected to the high-temperature black water pipe 3, and the first port of the first pipe 1 to be connected to the low-temperature black water drainage pipe 4. The heating water pipe 5 is connected to the second pipe 2 to form a loop.

[0029] Specifically, the second pipe 2 is connected to the heating water pipe 5, and the flow direction of the heating water in the second pipe 2 is the same as the reverse flow direction of the first pipe 1. When the first pipe 1 is in the forward flow mode, the cold and hot fluids flow into the heat exchanger from both ends in opposite directions. The temperature difference between the cold and hot fluids is large during the entire heat exchange process, which improves the heat exchange efficiency and allows the outlet temperature of the heating water to approach the inlet temperature of the high-temperature black water.

[0030] Black water contains a large number of solid particles. During forward flow, these particles settle towards the bottom of the pipe due to gravity, gradually accumulating to form a loose sediment layer. Over time, this layer thickens. Subsequent sedimentation builds up on top of the earlier layer, eventually causing it to occupy most of the pipe's cross-section and even completely block it. Furthermore, due to the pipe's structure, solid particles easily settle and accumulate in low-velocity areas during forward flow, ultimately clogging the pipe.

[0031] The first and second ports of the first pipeline 1 are connected to the high-temperature black water pipeline 3 and the low-temperature black water drainage pipeline 4 via control valves. When the control valve controls the first port of the first pipeline 1 to be connected to the high-temperature black water pipeline 3 and the second port of the first pipeline 1 to be connected to the low-temperature black water drainage pipeline 4, the high-temperature black water from the flash tank flows in the forward direction, that is, from the first port of the first pipeline 1 to the second port of the first pipeline 1. When the control valve controls the second port of the first pipeline 1 to be connected to the high-temperature black water pipeline 3 and the first port of the first pipeline 1 to be connected to the low-temperature black water drainage pipeline 4, the high-temperature black water from the flash tank flows in the reverse direction, that is, from the second port of the first pipeline 1 to the first port of the first pipeline 1.

[0032] This configuration allows the control valve to switch the black water flow from forward to reverse within the first pipe 1, altering the velocity distribution of the black water. The black water can then reach the low-velocity region of the forward flow, carrying away settled solid particles and preventing blockage in the first pipe 1. The control valve also improves the heat exchange efficiency of the first pipe 1 and the second pipe 2. This disclosed flash black water waste heat recovery device achieves efficient waste heat recovery while preventing black water blockage in the pipes.

[0033] Example 1: Reference Figure 1 A first pressure detection element 6 is installed on the high-temperature black water pipeline 3, and a second pressure detection element 7 is installed on the low-temperature black water drainage pipeline 4. The control valve is also configured to switch the black water flow from forward to reverse in the first pipeline 1 when the pressure difference between the first pressure detection element 6 and the second pressure detection element 7 reaches a preset pressure value. The preset pressure value is 0.08-0.15 MPa.

[0034] The first port of the first pipeline 1 is connected in parallel with a first channel and a second channel, and the second port of the first pipeline 1 is connected in parallel with a third channel and a fourth channel. The first channel and the fourth channel are configured to communicate with the high-temperature black water pipeline 3, and the second channel and the third channel are configured to communicate with the low-temperature black water drainage pipeline 4. The control valve includes a first switching valve 10 disposed in the first channel, a second switching valve 11 disposed in the second channel, a third switching valve 12 disposed in the third channel, and a fourth switching valve 13 disposed in the fourth channel. When the first switching valve 10 and the third switching valve 12 are open, and the second switching valve 11 and the fourth switching valve 13 are closed, the black water flows in the first pipeline 1 in the forward direction. When the second switching valve 11 and the fourth switching valve 13 are open, and the first switching valve 10 and the third switching valve 12 are closed, the black water flows in the reverse direction in the first pipeline 1.

[0035] Specifically, the first pressure sensing element 6 and the second pressure sensing element 7 are used to detect the pressure of black water before it enters the first pipe 1 and after it exits the first pipe 1. This pressure difference typically depends on the length and diameter of the first pipe 1, the fluid properties, and the flow velocity. The fluid properties usually do not change; the main change occurs when solid particles in the black water settle, altering the pipe diameter of the first pipe 1 and the flow velocity of the black water. When the pressure difference between the first pressure sensing element 6 and the second pressure sensing element 7 reaches a preset pressure value, it can be considered that a blockage has occurred in the first pipe 1. This embodiment uses 0.1 MPa as an example; it can be understood that the preset pressure value is specifically set according to the pipe parameters and the properties of the fluid.

[0036] The first port of the first pipeline 1 is connected to the high-temperature black water pipeline 3 through the first channel, and to the low-temperature black water drainage pipeline 4 through the second channel. The second port of the first pipeline 1 is connected to the high-temperature black water pipeline 3 through the fourth channel, and to the low-temperature black water drainage pipeline 4 through the third channel. Each channel is equipped with a first switch valve 10, a second switch valve 11, a third switch valve 12, and a fourth switch valve 13 to control the conduction status of each channel.

[0037] When the pressure difference between the first pressure sensing element 6 and the second pressure sensing element 7 reaches the preset pressure value, the second switch valve 11 and the fourth switch valve 13 open, and the first switch valve 10 and the third switch valve 12 close. Black water enters the second port of the first pipe 1 from the high-temperature black water pipe 3 through the fourth channel, and enters the low-temperature black water drainage pipe 4 from the first port of the first pipe 1 through the second channel. The black water flows in reverse in the first pipe 1 to flush the first pipe 1 and prevent the first pipe 1 from becoming blocked.

[0038] When the pressure difference between the first pressure sensing element 6 and the second pressure sensing element 7 is less than the preset pressure value, the first switching valve 10 and the third switching valve 12 open, and the second switching valve 11 and the fourth switching valve 13 close. Black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first channel, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the third channel. The black water flows in the first pipeline 1 in a forward direction, which improves the heat exchange efficiency of the heat exchanger and realizes the recovery and utilization of waste heat from the flash evaporation black water.

[0039] The first switching valve 10, the second switching valve 11, the third switching valve 12, and the fourth switching valve 13 are all hemispherical valves. When the hemispherical valve is closed, the edge of the valve core strongly scrapes the sealing surface like a knife edge to prevent impurities from getting stuck, which is particularly effective in controlling media containing solid particles.

[0040] The first pipeline 1 and the second pipeline 2 include spiral pipe sections, and the spiral pipe sections of the first pipeline 1 and the second pipeline 2 are wound together.

[0041] Specifically, the first pipeline 1 and the second pipeline 2 each include two spiral pipeline sections and one straight pipeline section, with the two spiral pipeline sections positioned on both sides of the straight pipeline section to form a U-shaped pipeline. The two spiral pipeline sections of the first pipeline 1 and the second pipeline 2 are wound together.

[0042] This design primarily extends the pipe length and increases heat exchange time, effectively improving heat exchange efficiency. Secondly, the spiral pipe structure is compact and space-saving; the spiral winding maximizes the heat exchange area per unit volume, making it suitable for space-constrained environments. The first pipe (1) is made of 254 or 316L stainless steel, with an internal corrosion-resistant coating applied via micro-electrolysis to prevent black water from causing wear and corrosion to the inner wall of the first pipe (1).

[0043] The high-temperature black water pipeline 3 is connected to the high-pressure flash tank 8, and the low-temperature black water drainage pipeline 4 is connected to the low-pressure flash tank 9. The flash black water waste heat recovery device disclosed herein is mainly used between the high-pressure flash tank 8 and the low-pressure flash tank 9. Since the high-pressure flash black water temperature can reach 161-164℃ and the flow rate can reach 179-230 t / h, it can serve as the core heat source for waste heat recovery. It is understood that the flash black water waste heat recovery device disclosed herein can also be applied between other flash evaporation processes, provided there is a high-heat source available.

[0044] Example 2: Reference Figure 1 The control valve is also configured to switch the flow of black water in the first pipeline 1 from forward to reverse when the black water flows forward for a first preset time, and to switch the flow of black water in the first pipeline 1 from reverse to forward when the black water flows backward for a second preset time. The second preset time is longer than the first preset time. The second preset time is twice the first preset time.

[0045] When the black water flows forward in the first pipeline 1 for a first preset time, the second switch valve 11 and the fourth switch valve 13 open, and the first switch valve 10 and the third switch valve 12 close. The black water enters the second port of the first pipeline 1 from the high-temperature black water pipeline 3 through the fourth channel, and enters the low-temperature black water drainage pipeline 4 from the first port of the first pipeline 1 through the second channel. The black water flows in reverse in the first pipeline 1 to flush the first pipeline 1 and prevent the first pipeline 1 from becoming blocked.

[0046] When the black water flows in reverse for a second preset time in the first pipeline 1, the first switch valve 10 and the third switch valve 12 open, and the second switch valve 11 and the fourth switch valve 13 close. The black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first channel, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the third channel. The black water flows in the first pipeline 1 in the forward direction, which improves the heat exchange efficiency of the heat exchanger and realizes the recovery and utilization of the waste heat of the flash evaporation black water.

[0047] To reduce the possibility of clogging and improve flushing efficiency, the duration of the black water's reverse flow is longer than the duration of its forward flow; that is, the second preset time is longer than the first preset time. The second preset time is typically twice the first preset time. In this embodiment, the first preset time is set to 4 hours, and the second preset time is set to 8 hours. It is understood that the specific settings for the first and second preset times are determined based on the pipe parameters and the properties of the fluid.

[0048] Example 3: Reference Figure 1When the black water flows forward in the first pipeline 1 for less than the first preset time, and the pressure difference between the first pressure detection element 6 and the second pressure detection element 7 reaches the preset pressure value, the second switch valve 11 and the fourth switch valve 13 open, and the first switch valve 10 and the third switch valve 12 close. The black water enters the second port of the first pipeline 1 from the high-temperature black water pipeline 3 through the fourth channel, and enters the low-temperature black water drainage pipeline 4 from the first port of the first pipeline 1 through the second channel. The black water flows in reverse in the first pipeline 1 to flush the first pipeline 1 and prevent the first pipeline 1 from becoming blocked.

[0049] When the black water flows in reverse for a second preset time in the first pipeline 1 and the pressure difference between the first pressure detection element 6 and the second pressure detection element 7 does not reach the preset pressure value, the first switch valve 10 and the third switch valve 12 open, and the second switch valve 11 and the fourth switch valve 13 close. The black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first channel, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the third channel. The black water flows in the first pipeline 1 in the forward direction, which improves the heat exchange efficiency of the heat exchanger and realizes the recovery and utilization of the waste heat of the flash evaporation black water.

[0050] Simultaneously, time and pressure detection control logic is employed to further prevent blockage of the first pipeline 1.

[0051] Example 4: Reference Figure 2 The control valve is a two-position four-way valve 14. The first valve port 141 of the two-position four-way valve 14 is connected to the high-temperature black water pipeline 3, the second valve port 142 of the two-position four-way valve 14 is connected to the low-temperature black water drainage pipeline 4, the third valve port 143 of the two-position four-way valve 14 is connected to the first port of the first pipeline 1, and the fourth valve port 144 of the two-position four-way valve 14 is connected to the second port of the first pipeline 1. When the two-position four-way valve 14 is in the first working position, the first valve port 141 and the third valve port 143 of the two-position four-way valve 14 are connected, the second valve port 142 and the fourth valve port 144 of the two-position four-way valve 14 are connected, and the black water flows in the first pipeline 1 in the forward direction. When the two-position four-way valve 14 is in the second working position, the second valve port 142 and the third valve port 143 of the two-position four-way valve 14 are connected, the first valve port 141 and the fourth valve port 144 of the two-position four-way valve 14 are connected, and the black water flows in the reverse direction in the first pipeline 1.

[0052] Two four-way valves 14 control the flow direction of the first pipeline 1, which reduces the number of switching valves and the number of channels, greatly saving the space of the device and facilitating the improvement of the flash black water waste heat recovery device in the flash evaporation system.

[0053] When the pressure difference between the first pressure sensing element 6 and the second pressure sensing element 7 reaches the preset pressure value, the two-position four-way valve 14 is in the second working position. The second valve port 142 and the third valve port 143 of the two-position four-way valve 14 are open, and the first valve port 141 and the fourth valve port 144 of the two-position four-way valve 14 are open. Black water enters the second port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the fourth valve port 144, and enters the low-temperature black water drainage pipeline 4 from the first port of the first pipeline 1 through the third valve port 143 and the second valve port 142. The black water flows in reverse in the first pipeline 1 to flush the first pipeline 1 and prevent the first pipeline 1 from becoming blocked.

[0054] When the pressure difference between the first pressure sensing element 6 and the second pressure sensing element 7 is less than the preset pressure value, the two-position four-way valve 14 is in the first working position. The first valve port 141 and the third valve port 143 of the two-position four-way valve 14 are open, and the second valve port 142 and the fourth valve port 144 of the two-position four-way valve 14 are open. Black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the third valve port 143, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the fourth valve port 144 and the second valve port 142. The black water flows in the first pipeline 1 in a positive direction, which improves the heat exchange efficiency of the heat exchanger and realizes the waste heat recovery and utilization of the flash evaporation black water.

[0055] Example 5: Reference Figure 2 When the black water flows forward in the first pipeline 1 for a first preset time, the two-position four-way valve 14 is in the second working position. The second valve port 142 and the third valve port 143 of the two-position four-way valve 14 are connected, and the first valve port 141 and the fourth valve port 144 of the two-position four-way valve 14 are connected. The black water enters the second port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the fourth valve port 144, and enters the low-temperature black water drainage pipeline 4 from the first port of the first pipeline 1 through the third valve port 143 and the second valve port 142. The black water flows in reverse in the first pipeline 1 to flush the first pipeline 1 and prevent the first pipeline 1 from being blocked.

[0056] When the black water flows in reverse for a second preset time in the first pipeline 1, the two-position four-way valve 14 is in the first working position. The first valve port 141 and the third valve port 143 of the two-position four-way valve 14 are connected, and the second valve port 142 and the fourth valve port 144 of the two-position four-way valve 14 are connected. The black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the third valve port 143, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the fourth valve port 144 and the second valve port 142. The black water flows in the forward direction in the first pipeline 1, which improves the heat exchange efficiency of the heat exchanger and realizes the waste heat recovery and utilization of the flash evaporation black water.

[0057] Example 6: Reference Figure 2 When the black water flows forward in the first pipeline 1 for less than the first preset time, and the pressure difference between the first pressure detection element 6 and the second pressure detection element 7 reaches the preset pressure value, the two-position four-way valve 14 is in the second working position. The second valve port 142 and the third valve port 143 of the two-position four-way valve 14 are open, and the first valve port 141 and the fourth valve port 144 of the two-position four-way valve 14 are open. The black water enters the second port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the fourth valve port 144, and enters the low-temperature black water drainage pipeline 4 from the first port of the first pipeline 1 through the third valve port 143 and the second valve port 142. The black water flows in reverse in the first pipeline 1 to flush the first pipeline 1 and prevent the first pipeline 1 from becoming blocked.

[0058] When the black water flows in reverse for a second preset time in the first pipeline 1 and the pressure difference between the first pressure detection element 6 and the second pressure detection element 7 does not reach the preset pressure value, the two-position four-way valve 14 is in the first working position. The first valve port 141 and the third valve port 143 of the two-position four-way valve 14 are open, and the second valve port 142 and the fourth valve port 144 of the two-position four-way valve 14 are open. The black water enters the first port of the first pipeline 1 from the high-temperature black water pipeline 3 through the first valve port 141 and the third valve port 143, and enters the low-temperature black water drainage pipeline 4 from the second port of the first pipeline 1 through the fourth valve port 144 and the second valve port 142. The black water flows in the first pipeline 1 in the forward direction, which improves the heat exchange efficiency of the heat exchanger and realizes the waste heat recovery and utilization of the flash evaporation black water.

[0059] The use of a two-position four-way valve 14 saves space in the device, while the use of time and pressure detection control logic further prevents blockage of the first pipeline 1.

[0060] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein. The scope of this disclosure is defined by the appended claims.

Claims

1. A flash black water waste heat recovery device, characterized in that, The flash black water waste heat recovery device includes: A heat exchanger having a first conduit (1) and a second conduit (2) arranged for mutual heat exchange: A control valve is provided between the high-temperature black water pipeline (3) from the flash tank, the low-temperature black water drainage pipeline (4) after heat exchange and cooling, and the first port and the second port of the first pipeline (1). The control valve is configured to switch the black water to flow in the first pipeline (1) in the forward or reverse direction. In the forward flow mode, the control valve controls the first port of the first pipeline (1) to be connected to the high temperature black water pipeline (3), and the second port of the first pipeline (1) to be connected to the low temperature black water drainage pipeline (4). In reverse flow mode, the control valve controls the second port of the first pipeline (1) to be connected to the high temperature black water pipeline (3), and the first port of the first pipeline (1) to be connected to the low temperature black water drainage pipeline (4). Heating water pipe (5) is connected to the second pipeline (2) to form a loop.

2. The flash black water waste heat recovery device according to claim 1, characterized in that, The high-temperature black water pipeline (3) is provided with a first pressure detection element (6), and the low-temperature black water drainage pipeline (4) is provided with a second pressure detection element (7). The control valve is also configured to control the black water in the first pipeline (1) to switch from forward flow to reverse flow when the pressure difference between the first pressure detection element (6) and the second pressure detection element (7) reaches a preset pressure value.

3. The flash black water waste heat recovery device according to claim 2, characterized in that, The preset pressure value is 0.08-0.15 MPa.

4. The flash black water waste heat recovery device according to claim 1 or 3, characterized in that, The control valve is also configured to control the black water in the first pipeline (1) to switch from forward flow to reverse flow when the black water in the first pipeline (1) runs forward for a first preset time, and to control the black water in the first pipeline (1) to switch from reverse flow to forward flow when the black water in the first pipeline (1) runs reverse for a second preset time, wherein the second preset time is greater than the first preset time.

5. The flash black water waste heat recovery device according to claim 4, characterized in that, The second preset time is twice the first preset time.

6. The flash black water waste heat recovery device according to claim 5, characterized in that, The first pipeline (1) and the second pipeline (2) include spiral pipeline sections, and the spiral pipeline sections of the first pipeline (1) and the second pipeline (2) are wound together.

7. The flash black water waste heat recovery device according to claim 6, characterized in that, The high-temperature black water pipeline (3) is connected to the high-pressure flash tank (8), and the low-temperature black water drainage pipeline (4) is connected to the low-pressure flash tank (9).

8. The flash black water waste heat recovery device according to claim 7, characterized in that, The first port of the first pipeline (1) is connected to a first channel and a second channel in parallel, and the second port of the first pipeline (1) is connected to a third channel and a fourth channel in parallel. The first channel and the fourth channel are configured to communicate with the high-temperature black water pipeline (3), and the second channel and the third channel are configured to communicate with the low-temperature black water drainage pipeline (4). The control valve includes a first switching valve (10) disposed in the first channel, a second switching valve (11) disposed in the second channel, a third switching valve (12) disposed in the third channel, and a fourth switching valve (13) disposed in the fourth channel. When the first switch valve (10) and the third switch valve (12) are open, and the second switch valve (11) and the fourth switch valve (13) are closed, the black water flows in the first pipeline (1) in the forward direction; When the second switch valve (11) and the fourth switch valve (13) are open, and the first switch valve (10) and the third switch valve (12) are closed, the black water flows in reverse in the first pipeline (1).

9. The flash black water waste heat recovery device according to claim 8, characterized in that, The first switching valve (10), the second switching valve (11), the third switching valve (12), and the fourth switching valve (13) are all hemispherical valves.

10. The flash black water waste heat recovery device according to claim 7, characterized in that, The control valve is a two-position four-way valve (14). The first valve port (141) of the two-position four-way valve (14) is connected to the high-temperature black water pipeline (3), the second valve port (142) of the two-position four-way valve (14) is connected to the low-temperature black water drainage pipeline (4), the third valve port (143) of the two-position four-way valve (14) is connected to the first port of the first pipeline (1), and the fourth valve port (144) of the two-position four-way valve (14) is connected to the second port of the first pipeline (1). When the two-position four-way valve (14) is in the first working position, the first valve port (141) and the third valve port (143) of the two-position four-way valve (14) are connected, the second valve port (142) and the fourth valve port (144) of the two-position four-way valve (14) are connected, and the black water flows in the first pipeline (1) in the forward direction. When the two-position four-way valve (14) is in the second working position, the second valve port (142) and the third valve port (143) of the two-position four-way valve (14) are connected, and the first valve port (141) and the fourth valve port (144) of the two-position four-way valve (14) are connected, and the black water flows in reverse in the first pipeline (1).

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