CN112229164B - Multi-stage heat pump drying parallel system and its working method - Google Patents

Abstract

The embodiment of the invention provides a multistage heat pump drying parallel system and a working method thereof. The system comprises: the system comprises a main machine room and a plurality of dryers, wherein the dryers are separated by a first partition board, the dryers comprise a drying room, a return air room and a buffer room which are sequentially arranged from bottom to top, a second partition board is arranged between the drying room and the return air room, return air channels communicated with the drying room and the return air room are formed at two ends of the second partition board, a circulating fan and a condenser of a heat pump unit are arranged in the return air room along the cross section of the return air room, the return air room and the buffer room are separated by a third partition board, a return air valve and an exhaust valve are arranged on the third partition board, and a fresh air valve is also arranged in the buffer room; the buffer chambers of the dryers are connected in parallel with the main machine chamber; a moisture discharge valve is provided in the main body chamber. According to the invention, the plurality of dryers are connected in parallel in the main machine room, so that a coupling drying operation mode of closed circulation and semi-open circulation is realized, materials in each drying room are uniformly dried, and the drying efficiency is improved.

Description

Multi-stage heat pump drying parallel system and its working method

Technical field

The invention relates to the technical field of heat pump drying, and in particular to a multi-stage heat pump drying parallel system and its working method.

Background technique

During the drying process, the traditional drying system emits a large amount of waste gas, which contains a large amount of waste heat, which results in low energy efficiency of the drying system and low energy utilization. The heat pump system can recover the latent heat and sensible heat in the exhaust gas during the drying process, and it has the advantages of low energy consumption, high temperature and humidity control accuracy, and high drying efficiency. Therefore, heat pump drying technology has significant advantages in the field of drying.

The prior art discloses a regenerative heat pump drying system (application number: 201610607496.8), which uses a similar parallel air supply dryer. The patent proposes a regenerative device to buffer the recycling of waste heat during the drying process. , but the drying uniformity of materials in the drying chamber is not considered, resulting in the material at the end of the drying chamber being relatively difficult to dry, which relatively prolongs the entire drying cycle.

Contents of the invention

Embodiments of the present invention provide a multi-stage heat pump drying parallel system and its working method to solve the problem in the prior art that the material at the end of the drying chamber is not easy to dry and the drying cycle is prolonged.

A multi-stage heat pump drying parallel system provided by the first aspect of the embodiment of the present invention includes: a host room and a plurality of dryers, and the plurality of dryers are separated by first partitions; wherein,

The dryer includes a drying chamber, a return air chamber and a buffer chamber arranged in sequence from bottom to top. A second partition is provided between the drying chamber and the return air chamber, and on both sides of the second partition The end forms a return air duct connected to the drying chamber and the return air chamber. A circulating fan and a condenser of the heat pump unit are arranged along the cross section of the return air chamber. The return air chamber and the buffer chamber pass through Separate by a third partition, and a return air valve and an exhaust valve are provided on the third partition, and a fresh air valve is also provided in the buffer chamber;

The buffer chamber of each dryer is connected in parallel to the host room;

A dehumidification valve is provided in the host room;

It also includes a fourth partition, and at least two sets of return air valves and exhaust valves are provided, wherein one set of return air valves and exhaust valves is disposed between the circulation fan and the condenser. On one side, another set of the return air valve and the exhaust valve are arranged on the other side of the circulation fan and the condenser, and the fourth partition is arranged in the buffer chamber and connects the The buffer chamber is divided into a return air side and an exhaust side, the return air valve is arranged on the return air side, and the exhaust valve is arranged on the exhaust side.

Wherein, the circulation fan is a forward and reverse rotating fan.

Wherein, a diverting structure is provided in the return air duct.

Wherein, the flow distribution structure includes multiple layers of arc-shaped air guide plates with different radii, one end of the arc-shaped air guide plate leads to the drying chamber, and the other end leads to the return air chamber.

It also includes an exhaust duct connected between the exhaust side and the main engine room.

Wherein, a plurality of guide plates are provided on the side of the third partition adjacent to the return air chamber, and the plurality of guide plates are evenly arranged along the length direction of the third partition.

Wherein, heat storage material is provided in the main engine room.

It also includes a feed door and an inspection door. The feed door is provided on the dryer and is located on the other side relative to the main machine room. The inspection door is provided on both ends of the main machine room.

According to another aspect of the embodiment of the present invention, a working method of a multi-stage heat pump drying parallel system includes:

During the drying process, the air flow in the drying chamber flows directionally through the circulating fan. After heat exchange between the high-temperature air and the material, it becomes low-temperature and high-humidity air, which enters the return air chamber. Part of the air enters through the exhaust valve and remains in the buffer chamber, and the other part of the air It enters the buffer chamber through the exhaust valve and is sent to the host room through the exhaust duct, where it is cooled and dehumidified by the heat pump unit;

When using closed-circuit circulation, open the return air valve, close the fresh air valve and the dehumidification valve, and the air entering the buffer chamber enters the return air chamber through the return air valve and mixes with the air discharged from the drying chamber;

When using a semi-open cycle, open the return air valve, fresh air valve and dehumidification valve. The air after being cooled and dehumidified by the heat pump unit passes through the dehumidification valve. The outside air enters the buffer chamber through the fresh air valve and then enters the return air valve through the return air valve. The air chamber is mixed with the air discharged from the drying chamber, and the mixed air is heated by the condenser to continue heat exchange with the material.

The embodiment of the present invention provides a multi-stage heat pump drying parallel system and its working method. The dryer is divided into a drying chamber, a return air chamber and a buffer chamber through partitions. Multiple dryers are connected in parallel to the host room. Through each air The opening and closing of the valve can realize the coupled drying operation mode of closed cycle and semi-open cycle, which avoids the problem of waste heat emission and recycling and the uneven distribution of energy consumption of the system, making the materials in each drying chamber dry evenly and improving the drying efficiency. efficiency.

Description of the drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a top view of a multi-stage heat pump drying parallel system provided by the present invention;

Figure 2 is a cross-sectional view of A-A in Figure 1 when the circulation fan is rotating forward;

Figure 3 is a cross-sectional view of A-A in Figure 1 when the circulation fan is reversed;

Figure 4 is a cross-sectional view along the line B-B in Figure 1 .

Reference signs:

1: Heat pump unit; 2: Condenser; 3: Circulation fan; 4: Second partition; 5: Fourth partition; 6: First exhaust valve; 7: Second exhaust valve; 8: Exhaust duct ; 9: First return air valve; 10: Second return air valve; 11: Fresh air valve; 12: Dehumidification valve; 13: Feed door; 14: Inspection door; 15: Drying room; 16: Return air room; 17: Host room; 18: Buffer room; 19: Diversion structure; 20: Guide plate; 21: First partition; 22: Third partition.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it can be a mechanical connection or a point connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

The following describes a multi-stage heat pump drying parallel system according to the embodiment of the present invention with reference to Figures 1-4, which includes: a host room 17 and multiple dryers. The multiple dryers are separated by first partitions 21 and connected to the host in parallel. Chamber 17, each drying chamber 15 operates independently without interfering with each other. The heat pump unit 1 is installed in the main engine room 17 .

The dryer includes a drying chamber 15, a return air chamber 16 and a buffer chamber 18 arranged in sequence from bottom to top. A second partition 4 is provided between the drying chamber 15 and the return air chamber 16, and between the second partition 4 Both ends form a return air duct connected to the drying chamber 15 and the return air chamber 16. The circulation fan 3 and the condenser 2 of the heat pump unit 1 are arranged along the cross section of the return air chamber 16. The return air chamber 16 and the buffer chamber 18 pass through The third partition 22 separates, and a return air valve and an exhaust valve are provided on the third partition 22 , and a fresh air valve 11 is also provided in the buffer chamber 18 . Specifically, the drying chamber 15 and the return air chamber 16 are connected through the return air ducts at both ends of the second partition 4. Driven by the circulating fan 3, the air flow can move in a direction to exchange heat with the materials. The condenser 2 in the return air chamber 16 is a part of the heat pump unit 1 (that is, the condenser 2 of the heat pump unit 1). The fresh air valve 11 provided in the buffer chamber 18 can be opened to allow outside air to enter the buffer chamber 18 and pass through the exhaust valve and The return air valve controls air to pass through the third partition 22 and then flow between the return air chamber 16 and the buffer chamber 18 .

The buffer chamber 18 of each dryer is connected to the main machine room 17 in parallel. It can be understood that multiple dryers are connected in parallel to the main machine room 17 , specifically the buffer chamber 18 is connected in parallel to the main machine room 17 , and the heat pump unit 1 in the main machine room 17 controls the temperature in the dryers.

A moisture dehumidification valve 12 is provided in the main machine room 17 , and the excess moisture in the main machine room 17 is discharged through the moisture dehumidification valve 12 .

Furthermore, a temperature and humidity sensor is provided in the return air chamber 16, and the opening angles of the heat pump unit 1 and each air valve are adjusted according to the monitored temperature and humidity. The heat pump unit 1 can adjust the temperature of the drying chamber 15 by adjusting the frequency of its compressor or starting and stopping.

The humidity of the drying room 15 is controlled through the exhaust valve, moisture exhaust valve 12, fresh air valve 11 and return air valve. Specifically, the exhaust valve and the return air valve are first used for regulation, and the evaporator of the heat pump unit 1 is used to remove moisture in the air. When it cannot meet the humidity requirements of the drying room 15, the exhaust valve, moisture dehumidification valve 12 and fresh air are then adjusted. Valve 11.

In the drying process, the drying intervals of each dryer are generally in different stages, so that the waste heat of each dryer can be shared. The excess waste heat of the dryer in the dehumidification stage will be recycled by the dryer in the preheating stage or with less waste heat. , to ensure that the waste heat of the dryer in the preheating stage can be utilized and that the waste heat of the dryer in the middle stage of drying can be fully utilized.

The embodiment of the present invention provides a multi-stage heat pump drying parallel system and its working method. The dryer is divided into a drying chamber 15, a return air chamber 16 and a buffer chamber 18 through partitions. Multiple dryers are connected in parallel in the host room 17 , through the opening and closing of each air valve, the coupled drying operation mode of closed cycle and semi-open cycle can be realized, which avoids the problem of waste heat emission recovery and uneven distribution of energy consumption of the system, so that the materials in each drying chamber 15 Dry evenly and improve drying efficiency.

In one embodiment, the circulation fan 3 is a forward and reverse rotating fan. As shown in Figures 2 and 3, the arrows respectively represent the flow directions of the air when the circulation fan 3 rotates forward and reversely. The use of forward and reverse switching of the circulation fan 3 not only improves the uniformity and drying efficiency of material drying, but also improves the efficiency of the heat pump.

In one embodiment, a diverting structure 19 is provided in the return air duct. Furthermore, the flow distribution structure 19 includes multiple layers of arc-shaped air guide plates with different radii. One end of the arc-shaped air guide plate leads to the drying chamber 15 and the other end leads to the return air chamber 16 . In this embodiment, the arc-shaped air guide plate is of multi-layer design, which not only functions to divert the flow, adjust the uniformity of the air flow, but also plays a diversion function. The splitting structure 19 may also include splitting fan blades to adjust the direction of the airflow.

In one embodiment, the multi-stage heat pump drying parallel system also includes a fourth partition 5, and at least two sets of return air valves and exhaust valves are provided, where the return air valve and exhaust valve of one set are provided between the circulating fan and the condensation fan. On one side of the device, another set of return air valves and exhaust valves are provided on the other side of the circulation fan and condenser. The fourth partition 5 is provided in the buffer chamber 18 and separates the buffer chamber 18 into the return air side and the return air side. On the exhaust side, the return air valve is set on the return air side, and the exhaust valve is set on the exhaust side. It can be understood that the airflow is controlled by the exhaust valve to be discharged from the return air chamber 16 to the exhaust side of the buffer chamber 18, and the airflow is controlled by the return air valve to flow back from the buffer chamber 18 to the return air side of the return air chamber 16, so that the air returns. Wind and exhaust air do not interfere with each other. Two groups of return air valves and exhaust valves are respectively used, namely the first return air valve 9, the second return air valve 10, the first exhaust valve 6 and the second exhaust valve 7, which can be adapted to the normal operation of the circulation fan 3. Reverse the two working states (as shown in Figures 2 and 3), and open (or close) the corresponding return air valve and exhaust valve according to the operating state of the circulation fan 3.

In one embodiment, the multi-stage heat pump drying parallel system also includes an exhaust duct 8 , which is connected between the exhaust side and the host room 17 . It can be understood that the main machine room 17 is connected with the dryer, and the air in the main machine room 17 will enter the return air side of the buffer room 18 , while the air on the exhaust side will be discharged to the main machine room 17 through the exhaust duct 8 .

In one embodiment, a plurality of guide plates 20 are provided on a side of the third partition 22 adjacent to the return air chamber 16 , and the plurality of guide plates 20 are evenly arranged along the length direction of the third partition 22 . The function of the guide plate 20 in this embodiment is to introduce the air from the return air chamber 16 into the buffer chamber 18. The guide plate 20 can also be replaced by a fan.

In one embodiment, it also includes a feed door 13 and an inspection door 14 . The feed door 13 is provided on the dryer and is located on the other side relative to the main machine room 17 . The inspection door 14 is provided on both ends of the main machine room 17 . The feed door 13 is opened, and materials can enter the dryer through the feed door 13. The inspection door 14 is used for daily inspection of the main machine room 17 by the staff.

In one embodiment, a heat storage material is provided in the main machine room 17 to regulate the temperature of the main machine room 17 during the drying process. When the temperature in the main machine room 17 is low, the heat storage material releases heat. When the main machine room 17 When the temperature is high, the thermal storage material absorbs heat. When there are strict requirements on the humidity of the drying chamber 15, especially the moisturizing stage, it is required that the exhaust gas in the drying chamber 15 cannot be discharged into the host room 17, which will cause the temperature of the host room 17 to drop sharply. The use of heat storage materials can reduce the size of the host room. The degree of temperature change within 17 days.

According to an embodiment of the present invention, a working method of a multi-stage heat pump drying parallel system according to the above embodiment is also provided, including:

During the drying process, the air flow in the drying chamber 15 flows directionally through the circulating fan 3. After heat exchange with the material, the high-temperature air becomes low-temperature and high-humidity air, which enters the return air chamber 16. A part of the air enters through the exhaust valve and remains in the buffer chamber. 18, another part of the air enters the buffer chamber 18 through the exhaust valve and is sent to the host room 17 through the exhaust duct, where it is cooled and dehumidified by the heat pump unit 1;

When using a closed-circuit cycle, open the return air valve, close the fresh air valve 11 and the dehumidification valve 12, and the air entering the buffer chamber 18 enters the return air chamber 16 through the return air valve and mixes with the air discharged from the drying chamber 15;

When a semi-open cycle is adopted, the return air valve, fresh air valve 11 and dehumidification valve 12 are opened. The air cooled and dehumidified by the heat pump unit 1 passes through the dehumidification valve 12, and the outside air enters the buffer chamber 18 through the fresh air valve 11 and then passes through. The return air valve enters the return air chamber 16 and mixes with the air discharged from the drying chamber 15. The mixed air is heated by the condenser 2 to continue heat exchange with the material.

Through the control of the heat pump unit 1 and each air valve, the closed cycle and semi-open cycle coupling drying modes can be realized to improve the drying efficiency. The drying chamber 15 is connected in parallel to the host room 17 to ensure that the materials in each drying chamber 15 are evenly dried. .

Furthermore, according to the forward and reverse rotation status of the circulation fan 3, the multi-stage heat pump drying parallel system also has different working methods, as follows:

As shown in Figure 2, the circulation fan 3 drives the air flow in the forward direction, and the air in the drying chamber 15 flows clockwise. During the drying process, the second exhaust valve 7 and the second return air valve 10 are in a closed state. The high-temperature air exchanges heat and mass with the materials and becomes low-temperature and high-humidity air and then enters the return air chamber 16 through the shunt structure 19. A part of the air enters the buffer chamber 18 through the first exhaust valve 6 and enters the main engine room 17 through the exhaust duct 8. It is cooled and dehumidified by the heat pump unit 1. When a closed-circuit circulation is used, the air in the buffer chamber 18 is discharged into the return air chamber 16 through the first return air valve 9, and is mixed with the air discharged from the drying chamber 15 in the return air chamber 16; when a semi-open circulation mode is used , the air cooled and dehumidified by the heat pump unit 1 is discharged to the outside environment through the dehumidification valve 12. Open the fresh air valve 11, and the outside air is discharged into the return air chamber 16 through the first return air valve 9 of the buffer chamber 18, and is discharged with the drying chamber 15 of air mixing. The mixed air is sent to the condenser 2 by the circulating fan 3, and is humidly heated by the condenser 2. The heated high-temperature air is discharged into the drying chamber 15 through the split structure 19, and continues to exchange heat and mass with the material.

As shown in Figure 3, the circulation fan 3 drives the air flow in reverse direction, and the air in the drying chamber 15 flows counterclockwise. During the drying process, the first exhaust valve 6 and the first return air valve 9 are in a closed state. The high-temperature air exchanges heat and mass with the materials and becomes low-temperature and high-humidity air and then enters the return air chamber 16 through the shunt structure 19. Part of the air enters the buffer chamber 18 through the second exhaust valve 7 and enters the main engine room 17 through the exhaust duct 8. It is cooled and dehumidified by the heat pump unit 1. When a closed-circuit circulation is used, the air in the buffer chamber 18 is discharged into the return air chamber 16 through the second return air valve 10, and is mixed with the air discharged from the drying chamber 15 in the return air chamber 16; when a semi-open circulation mode is used , the air cooled and dehumidified by the heat pump unit 1 is discharged to the outside environment through the dehumidification valve 12, the fresh air valve 11 is opened, and the outside air is discharged into the return air chamber 16 through the first return air valve 9 of the buffer chamber 18, and is discharged with the drying room 15 of air mixing. The mixed air is sent to the condenser 2 by the circulating fan 3, and is humidly heated by the condenser 2. The heated high-temperature air is discharged into the drying chamber 15 through the split structure 19, and continues to exchange heat and mass with the materials.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be used Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent substitutions are made to some of the technical features; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (8)

1. A multistage heat pump drying parallel system, comprising: a main machine chamber and a plurality of dryers, wherein the dryers are separated by a first partition board; wherein,

the dryer comprises a drying chamber, a return air chamber and a buffer chamber which are sequentially arranged from bottom to top, a second partition plate is arranged between the drying chamber and the return air chamber, return air channels communicated with the drying chamber and the return air chamber are formed at two ends of the second partition plate, a circulating fan and a condenser of a heat pump unit are arranged in the return air chamber along the cross section of the return air chamber, the return air chamber and the buffer chamber are separated by a third partition plate, a return air valve and an exhaust valve are arranged on the third partition plate, and a fresh air valve is also arranged in the buffer chamber;

the buffer chambers of the respective dryers are connected in parallel to the main machine chamber;

a dehumidifying valve is arranged in the main machine room;

the air return valve and the air exhaust valve are arranged on one side of the circulating fan and one side of the condenser, the air return valve and the air exhaust valve of the other group are arranged on the other side of the circulating fan and the other side of the condenser, the fourth partition plate is arranged in the buffer chamber and divides the buffer chamber into an air return side and an air exhaust side, the air return valve is arranged on the air return side, and the air exhaust valve is arranged on the air exhaust side; wherein,

the circulating fan is a positive and negative rotating fan.

2. The multi-stage heat pump drying parallel system according to claim 1, wherein a shunt structure is provided in the return air duct.

3. The multi-stage heat pump drying parallel system of claim 2, wherein the flow dividing structure comprises a plurality of layers of arc-shaped flow guiding plates with different radiuses, one end of the arc-shaped flow guiding plates is communicated with the drying chamber, and the other end is communicated with the return air chamber.

4. The multi-stage heat pump drying parallel system of claim 1, further comprising an exhaust duct connected between the exhaust side and the main machine room.

5. The parallel system of claim 1, wherein a plurality of baffles are disposed on a side of the third partition plate adjacent to the return air chamber, and the plurality of baffles are uniformly disposed along a length direction of the third partition plate.

6. The multi-stage heat pump drying parallel system according to claim 1, wherein a heat storage material is provided in the main machine chamber.

7. The multi-stage heat pump drying parallel system of claim 1, further comprising a feed gate disposed at the dryer on the other side relative to the main machine chamber and an inspection gate disposed at both ends of the main machine chamber.

8. A method of operating a multistage heat pump drying parallel system according to any one of claims 1 to 7, comprising:

in the drying process, air flow in the drying chamber directionally flows through a circulating fan, high-temperature air is changed into low-temperature high-humidity air after heat exchange with materials, the low-temperature high-humidity air enters a return air chamber, and part of air enters a buffer chamber through an exhaust valve and is sent to a host chamber through an exhaust duct, and the heat pump unit is used for cooling and dehumidifying;

when closed circulation is adopted, a return air valve is opened, a fresh air valve and a moisture discharging valve are closed, and air entering the buffer chamber enters the return air chamber through the return air valve and is mixed with air discharged from the drying chamber;

when the semi-open circulation is adopted, the return air valve, the fresh air valve and the dehumidifying valve are opened, air cooled and dehumidified by the heat pump unit passes through the dehumidifying valve, external air enters the buffer chamber through the fresh air valve and then enters the return air chamber through the return air valve, and is mixed with air exhausted from the drying chamber, and the mixed air is heated by the condenser to be continuously subjected to heat exchange with materials.