Low-temperature drying system capable of dehumidifying up and down simultaneously

Abstract

According to the low-temperature drying system capable of dehumidifying up and down at the same time, the dehumidifying efficiency and the drying efficiency can be effectively improved through the mode that the upper circulating air path and the lower circulating air path are used for dehumidifying at the same time. The low-temperature drying system comprises a drying chamber and a heat exchange unit, dynamic drying of sludge is achieved in the drying chamber in an up-down layering mode, the drying chamber is communicated with the heat exchange unit through an air return opening, and a pre-cooler is arranged on an air return loop of the heat exchange unit and used for pre-cooling return air so that the return air can reach the dew point temperature; the return air is divided into two paths after passing through the pre-cooler, namely an upper circulating air path and a lower circulating air path; an upper cooler and an upper heater are sequentially arranged in the upper circulating air path, and air heated by the upper heater returns to the drying chamber through an upper air outlet; a lower cooler and a lower heater are sequentially arranged in the lower circulating air path, and air heated by the lower heater returns to the drying chamber through the lower air outlet.

Description

Technical Field

[0001] The utility model relates to a low-temperature drying system, in particular to a low-temperature drying system with upper and lower dehumidification capabilities simultaneously, belonging to the technical field of sludge low-temperature drying. Background Art

[0002] The air circulation system of the traditional heat source type low temperature drying equipment includes an upper circulation air path and a lower circulation air path. The lower circulation air path is dehumidified and heated, while the upper circulation air path is directly heated without dehumidification. Its operating principle is as follows: Figure 1 As shown: the air with high humidity coming out of the sludge in the drying chamber returns to the heat exchange unit, and then is divided into two paths, namely the upper circulation air path and the lower circulation air path; the air in the lower circulation air path passes through the cooler to condense the moisture in the air and becomes air with a lower moisture content (i.e. dehumidification), and then after being heated by the heater, the air becomes dry and hot air, and then returns to the drying chamber to heat and dry the sludge; the air in the upper circulation air path does not pass through the cooler for cooling and dehydration, but directly passes through the heater to heat the air and then returns to the drying chamber to heat the sludge.

[0003] In the existing low-temperature drying technology, the lower circulation air duct is used for dehumidification and heating, and the upper circulation air duct is directly heated without dehumidification. The reason is that in the drying chamber, the sludge is arranged in layers. It is generally believed in the field that the upper layer of sludge has a higher humidity, so there is a certain humidity difference with the return air, and the essence of evaporation is humidity difference, so there is no need to dehumidify the wind in the upper circulation air duct; in addition, the existing cognition is that the evaporation rate of the sludge is low before the temperature is increased, and the evaporation rate is high after the temperature is increased. Therefore, it is believed that temperature is the key to affecting dehumidification, and the sludge temperature in the upper layer of the drying chamber is relatively low. Based on this, the wind in the upper circulation air duct first needs to heat the sludge to increase the sludge temperature as soon as possible. In the upper circulation air duct, it is easier to increase the temperature without dehumidification. Therefore, the upper circulation air duct is directly heated without dehumidification.

[0004] However, in the actual drying process, it is found that evaporation occurs while the sludge is heating up; and before the sludge temperature rises, the evaporation rate is also very high, and the evaporation rate is mainly related to the humidity of the sludge. Therefore, for the sludge with lower temperature in the upper layer, the humidity difference will also affect the drying efficiency. The higher the humidity difference, the faster the drying rate. However, in the existing low-temperature drying equipment, the upper circulation does not dehumidify, resulting in a high humidity in the upper circulation wind, which is not conducive to sludge drying. Utility Model Content

[0005] In view of this, the utility model provides a low-temperature drying system with upper and lower dehumidification at the same time, which can effectively improve the dehumidification efficiency and drying efficiency by simultaneously dehumidifying the upper circulation air duct and the lower circulation air duct.

[0006] The technical solution of the utility model is: a low-temperature drying system with upper and lower dehumidification, comprising: a drying chamber and a heat exchange unit; the drying chamber adopts an upper and lower layered method to realize dynamic drying of sludge, and the drying chamber and the heat exchange unit are connected through a return air port; the characteristics are:

[0007] The return air circuit of the heat exchange unit is provided with a precooler for precooling the return air so that the return air reaches the dew point temperature;

[0008] The return air is divided into two paths after passing through the pre-cooler, namely an upper circulation air path and a lower circulation air path;

[0009] The upper circulating air path is provided with an upper cooler and an upper heater in sequence, and the air heated by the upper heater returns to the drying chamber through the upper air outlet;

[0010] The lower circulating air path is provided with a lower cooler and a lower heater in sequence, and the air heated by the lower heater returns to the drying chamber through the lower air outlet.

[0011] As a preferred embodiment of the present invention: a bypass passage is provided between the passage before the return air enters the precooler and the upper heater, and part of the return air directly enters the upper heater through the bypass passage.

[0012] As a preferred embodiment of the present invention, the return air directly entering the upper heater through the bypass passage does not exceed 25% of the total return air entering the heat exchange unit from the return air port.

[0013] As a preferred embodiment of the present invention: in the heat exchange unit, there is a chamber A between the return air outlet and the precooler, and above the chamber A is a chamber B located between the upper cooler and the upper heater; the top plate of the chamber A is the bottom plate of the chamber B, and a plurality of bypass holes that can be controlled to open and close are processed on the top plate of the chamber A as bypass passages.

[0014] As a preferred embodiment of the present invention, the air volume entering the upper circulation air passage is greater than the air volume entering the lower circulation air passage.

[0015] As a preferred embodiment of the utility model: the precooler, upper cooler, upper heater, lower cooler and lower heater constitute a heat exchange module, two heat exchange modules are symmetrically arranged inside the heat exchange unit, and the return air outlet is arranged between the two heat exchange modules.

[0016] As a preferred embodiment of the utility model: the precooler, upper cooler, upper heater, lower cooler and lower heater constitute a heat exchange module, two heat exchange modules are symmetrically arranged inside the heat exchange unit, and each heat exchange module is provided with a return air outlet connected to the drying chamber.

[0017] Beneficial effects:

[0018] (1) In the present invention, in the heat exchange unit of the low-temperature drying system, a solution of simultaneous upper and lower dehumidification is adopted, that is, in the upper circulation air path, the upper circulation air is first cooled by the upper cooler and then heated, thereby realizing condensation and dehumidification of the upper circulation air; the upper circulation air after cooling has lower humidity, which is more conducive to sludge drying.

[0019] (2) In the present invention, a precooler is provided on the return air circuit of the heat exchange unit for precooling the return air so that the return air reaches the dew point temperature, which is convenient for subsequent dehumidification. The upper circulation air path and the lower circulation air path share the precooler, which can effectively save the internal space of the heat exchange unit.

[0020] (3) In the present invention, a bypass passage is provided between the passage before the return air enters the precooler and the upper heater, so that a portion of the return air directly enters the upper heater without passing through the precooler and the upper cooler, thereby facilitating the increase of the temperature of the air heated by the upper heater.

[0021] (4) In the present invention, a plurality of bypass holes capable of being controlled to open and close are used as bypass passages, whereby the number of bypass holes opened can be adjusted according to usage requirements to adjust the proportion of return air directly entering the upper heater, thereby optimizing the working conditions of the heat exchange unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the working principle of the upper circulating air path and the lower circulating air path of the traditional heat source type low temperature drying equipment;

[0023] Figure 2 The figure is a schematic diagram of the working principle of the upper circulation air circuit and the lower circulation air circuit of the low-temperature drying system with upper and lower dehumidification simultaneously of the utility model.

[0024] Figure 3 It is a structural schematic diagram of a low-temperature drying system with simultaneous dehumidification from top to bottom;

[0025] Figure 4 This is a schematic diagram of the structure of the heat exchange unit in a low-temperature drying system with simultaneous upper and lower dehumidification.

[0026] Among them: 1-drying chamber, 2-heat exchange unit, 3-precooler, 4-upper cooler, 5-upper heater, 6-lower cooler, 7-lower heater. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] Embodiment 1:

[0029] The present embodiment provides a low-temperature drying device that dehumidifies both the upper and lower parts simultaneously, and improves the dehumidification efficiency and the drying efficiency by dehumidifying both the upper circulation air duct and the lower circulation air duct simultaneously.

[0030] like Figure 2 and Figure 3 As shown, the low-temperature drying system with upper and lower dehumidification includes: a drying chamber 1 and a heat exchange unit 2; the drying chamber 1 adopts an upper and lower layered method to realize dynamic drying of sludge; the drying chamber 1 and the heat exchange unit 2 are connected through a return air port; as an example, a return air port connected to the heat exchange unit 2 is arranged between the upper sludge conveyor belt and the lower sludge conveyor belt in the drying chamber 1; the hot air entering the drying chamber 1 passes through the sludge, and evaporates the water in the sludge; then the sludge coming out of the drying chamber 1 contains The wind with higher humidity enters the heat exchange unit 2 from the return air port as the return air; a precooler 3 is provided on the return air circuit of the heat exchange unit 2 for precooling the return air. The function of the precooler 3 is to remove the sensible heat in the return air (i.e., the precooler 3 cools but does not dehumidify) so that the return air reaches the dew point temperature; the return air entering the heat exchange unit 2 is first cooled by the precooler 3 to increase the relative humidity of the air (preferably, the relative humidity of the return air reaches 100% through the precooler 3) to facilitate subsequent dehumidification. The use of a shared precooler for the upper circulation air path and the lower circulation air path can effectively save the internal space of the heat exchange unit 2.

[0031] After passing through the precooler 3, the return air is divided into two paths, namely an upper circulation air path and a lower circulation air path; the upper circulation air path is provided with an upper cooler 4 and an upper heater 5 in sequence, whereby the wind in the upper circulation air path first passes through the upper cooler 4 to condense the moisture in the wind and turns it into air with a lower moisture content, and then after being heated by the upper heater 5, the air becomes dry and hot air, and finally returns to the drying chamber 1 through the upper air outlet to heat and dry the sludge; the lower circulation air path is provided with a lower cooler 6 and a lower heater 7 in sequence, whereby the wind in the lower circulation air path first passes through the lower cooler 6 to condense the moisture in the wind and turns it into air with a lower moisture content, and then after being heated by the lower heater 7, the air becomes dry and hot air, and finally returns to the drying chamber 1 through the lower air outlet to heat and dry the sludge.

[0032] Therefore, in the heat exchange unit, in the upper circulation air path, the upper circulation air is first cooled by the upper cooler 4 and then heated, thereby achieving condensation and dehumidification of the upper circulation air; the upper circulation air after cooling has lower humidity, which is more conducive to sludge drying.

[0033] At the same time, considering that the moisture content of the upper sludge in the drying chamber 1 is higher than that of the lower sludge, the air volume of the return air entering the upper circulation air path is controlled to be greater than the air volume entering the lower circulation air path, and the ratio of the air volume of the return air entering the upper circulation air path to the air volume entering the lower circulation air path is 2:1 to 3:1.

[0034] Embodiment 2:

[0035] On the basis of the above-mentioned embodiment 1, a bypass passage is further provided between the passage before the return air enters the precooler 3 and the upper heater 5, so that a part of the return air does not pass through the precooler 3 and the upper cooler 5 but directly enters the upper heater 5 through the bypass passage, thereby helping to increase the temperature of the air after being heated by the upper heater (that is, it can increase the average temperature of the air before the upper heater, which is beneficial to increase the air temperature after the upper heater under the same heating power of the upper heater).

[0036] As an embodiment, in the heat exchange unit 2, there is a chamber A between the return air port and the precooler 3, and above the chamber A is a chamber B located between the upper cooler 4 and the upper heater 5; the top plate of the chamber A is the bottom plate of the chamber B, and a number of bypass holes that can be controlled to open and close (such as by inserting and removing a plunger in the bypass hole to achieve the control of the opening and closing of the bypass hole) are processed on the top plate of the chamber A as a bypass passage; thereby, part of the return air directly enters the upper heater 5. According to the test, the number of bypass holes opened is adjusted to adjust the proportion of the return air directly entering the upper heater 5, and the return air directly entering the upper heater 5 through the bypass passage does not exceed 25% of the total return air entering the heat exchange unit 2 from the return air port; preferably 5% to 10%.

[0037] Embodiment 3:

[0038] Based on the above-mentioned Embodiments 1 and 2, this embodiment provides a layout of a low-temperature drying device that dehumidifies both top and bottom.

[0039] like Figure 4 As shown, the precooler 3, the upper cooler 4, the upper heater 5, the lower cooler 6 and the lower heater 7 constitute a heat exchange module. Two heat exchange modules are symmetrically arranged inside the heat exchange unit, and the return air outlet is arranged between the two heat exchange modules. That is, for the heat exchange unit 2, a layout of upper and lower air outlet and middle air return is adopted.

[0040] Embodiment 4:

[0041] Based on the above-mentioned Embodiments 1 and 2, this embodiment provides another layout of low-temperature drying equipment with simultaneous upper and lower dehumidification.

[0042] The precooler 3, the upper cooler 4, the upper heater 5, the lower cooler 6 and the lower heater 7 constitute a heat exchange module. In this embodiment, two heat exchange modules are symmetrically arranged inside the heat exchange unit 2. Each heat exchange module is provided with a return air port connected to the drying chamber, that is, for the heat exchange unit 2, a layout of upper and lower air outlet and left and right air return is adopted.

[0043] Although the utility model has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the utility model. Therefore, these modifications or improvements made without departing from the spirit of the utility model are within the scope of protection claimed by the utility model.

Claims

1. A low-temperature drying system for simultaneous upper and lower dehumidification, comprising: Drying chamber and heat exchange unit; the drying chamber adopts an upper and lower layered method to realize dynamic drying of sludge, and the drying chamber and the heat exchange unit are connected through a return air port; characterized in that: The return air circuit of the heat exchange unit is provided with a precooler for precooling the return air so that the return air reaches the dew point temperature; The return air is divided into two paths after passing through the pre-cooler, namely an upper circulation air path and a lower circulation air path; The upper circulating air path is provided with an upper cooler and an upper heater in sequence, and the air heated by the upper heater returns to the drying chamber through the upper air outlet; The lower circulating air path is provided with a lower cooler and a lower heater in sequence, and the air heated by the lower heater returns to the drying chamber through the lower air outlet.

2. The low-temperature drying system for simultaneous upper and lower dehumidification as claimed in claim 1, characterized in that: A bypass passage is provided between the passage before the return air enters the precooler and the upper heater, and part of the return air directly enters the upper heater through the bypass passage.

3. The low-temperature drying system for simultaneous upper and lower dehumidification as claimed in claim 2, characterized in that: The return air directly entering the upper heater through the bypass passage does not exceed 25% of the total return air entering the heat exchange unit from the return air port.

4. The low-temperature drying system for simultaneous upper and lower dehumidification as claimed in claim 2 or 3, characterized in that: In the heat exchange unit, there is a chamber A between the return air port and the precooler, and above the chamber A is a chamber B located between the upper cooler and the upper heater; the top plate of the chamber A is the bottom plate of the chamber B, and a plurality of bypass holes that can be controlled to open and close are processed on the top plate of the chamber A as bypass passages.

5. The low-temperature drying system for simultaneous upper and lower dehumidification according to any one of claims 1 to 3, characterized in that: The amount of air entering the upper circulation air passage is greater than the amount of air entering the lower circulation air passage.

6. The low-temperature drying system for simultaneous upper and lower dehumidification according to any one of claims 1 to 3, characterized in that: The precooler, upper cooler, upper heater, lower cooler and lower heater constitute a heat exchange module. Two heat exchange modules are symmetrically arranged inside the heat exchange unit, and the return air outlet is arranged at a position between the two heat exchange modules.

7. The low-temperature drying system for simultaneous upper and lower dehumidification according to any one of claims 1 to 3, characterized in that: The precooler, upper cooler, upper heater, lower cooler and lower heater constitute a heat exchange module. Two heat exchange modules are symmetrically arranged inside the heat exchange unit, and each heat exchange module is provided with a return air port connected to the drying chamber.

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