Heat dissipation method of sludge drying system

Abstract

The present invention provides a heat dissipation method for a sludge drying system, wherein the sludge drying system includes a heat pump unit, and a DC heat dissipation fan and an AC heat dissipation fan corresponding to the heat pump unit; the method includes the following steps: obtaining the circulating air outlet temperature T of the sludge drying system; if the circulating air outlet temperature T> the first target temperature T1, starting the unactivated DC heat dissipation fan according to the set start-up sequence; if the circulating air outlet temperature T> the second target temperature T2, and the DC heat dissipation fans have all been turned on and have reached the first operating state, starting the unactivated AC heat dissipation fan according to the set start-up sequence; wherein the first target temperature T1<the second target temperature T2. Compared with the prior art, the present invention uses both a DC heat dissipation fan and an AC heat dissipation fan to dissipate the heat of the condenser of the heat pump unit, which can simultaneously meet the requirements of the sludge drying effect and the equipment cost.

Description

Technical Field

[0001] The invention relates to the field of sludge drying, and in particular to a heat dissipation method of a sludge drying system. Background Art

[0002] Sludge drying system is a kind of equipment used to remove water from sludge. Figure 1 As shown, the sludge drying system includes a conveyor belt A for conveying sludge and a heat pump unit for removing moisture from the sludge. The heat pump unit specifically includes a compressor 10, a condenser 20, an expansion valve 30, an evaporator 40 and a circulating fan.

[0003] When the heat pump unit is in operation, the compressor 10 compresses the refrigerant to increase the temperature of the refrigerant, and transports the refrigerant to the condenser 20, where the refrigerant releases heat; then, the refrigerant is transported to the expansion valve 30, which reduces the temperature and pressure of the refrigerant and transports the refrigerant to the evaporator 40, where the refrigerant absorbs heat; finally, the refrigerant is transported from the evaporator 40 to the compressor 10, where it is compressed again, thereby forming a cycle.

[0004] The condenser 20 heats the circulating gas, and the heated circulating gas is transported to the conveyor belt A by the circulating fan. The moisture in the sludge on the conveyor belt A is transferred to the circulating gas, and the humidity of the circulating gas increases and the temperature decreases. Subsequently, the circulating gas passing through the conveyor belt A is transported to the evaporator 40, and the evaporator 40 cools the circulating gas and liquefies the moisture in the circulating gas, thereby removing the moisture in the circulating gas. Finally, the circulating gas passing through the evaporator 40 is transported back to the condenser 20, and the condenser 20 heats the circulating gas again, thereby forming a cycle.

[0005] The temperature of the circulating gas flowing out of the condenser 20, i.e., the circulating air outlet temperature T, needs to be controlled within a certain range. If the circulating air outlet temperature T is too low, it will affect the efficiency of sludge drying. If the circulating air outlet temperature T is too high, it will affect the safe operation of the heat pump unit and cause the heat pump unit to malfunction. The air outlet temperature T can be adjusted by setting a heat dissipation fan on the condenser 20 to discharge excess heat to the external environment. Specifically, when the heat discharged by the heat dissipation fan increases, the heat transferred from the condenser 20 to the circulating gas decreases, and the air outlet temperature T decreases; when the heat discharged by the heat dissipation fan decreases, the heat transferred from the condenser 20 to the circulating gas increases, and the air temperature T increases.

[0006] Common cooling fans include DC cooling fans and AC cooling fans. The speed of the DC cooling fan can be adjusted to reduce the fluctuation of the circulating air outlet temperature T, thereby achieving a dynamic balance of heat and a better sludge drying effect, but the cost of the DC cooling fan is relatively high; the speed of the AC cooling fan cannot be adjusted, which will cause a large fluctuation of the circulating air outlet temperature T, making it difficult to achieve a dynamic balance of heat, and the sludge drying effect is relatively poor, but the cost of the AC cooling fan is lower; in the existing sludge dryer, a DC cooling fan or an AC cooling fan is used alone to dissipate heat for the condenser 20, which is difficult to simultaneously meet the requirements of sludge drying effect and equipment cost. Summary of the invention

[0007] Based on this, the object of the present invention is to provide a heat dissipation method for a sludge drying system to simultaneously meet the requirements of sludge drying effect and equipment cost.

[0008] The present invention provides a heat dissipation method for a sludge drying system, wherein the sludge drying system comprises a heat pump unit, and a DC heat dissipation fan and an AC heat dissipation fan corresponding to the heat pump unit; the method comprises the following steps:

[0009] Obtaining the circulating air outlet temperature T of the sludge drying system;

[0010] If the circulating air outlet temperature T> the first target temperature T1, the DC cooling fan that is not turned on is started according to the set start sequence;

[0011] If the circulating air outlet temperature T> the second target temperature T2, and all DC cooling fans have been turned on and reached the first operating state, the unturned AC cooling fans are started according to the set start sequence; wherein the first target temperature T1<the second target temperature T2.

[0012] Further, the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; starting the unstarted DC cooling fan according to a set start sequence specifically includes the following steps:

[0013] Starting the first DC cooling fan;

[0014] If the circulating air outlet temperature T> the third target temperature T3, and the first DC cooling fan reaches the second operating state, the second DC cooling fan is started; wherein the first target temperature T1<the third target temperature T3<the second target temperature T2.

[0015] Further, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; starting the unstarted AC cooling fan according to a set start sequence specifically includes the following steps:

[0016] Starting the first AC cooling fan;

[0017] If the circulating air outlet temperature T>the fourth target temperature T4, the second AC cooling fan is started; wherein the fourth target temperature T4>the second target temperature T2.

[0018] Furthermore, the method further comprises the following steps:

[0019] If the circulating air outlet temperature T is less than the fifth target temperature T5, and all DC cooling fans are turned on, and all or part of the AC cooling fans are turned on, and the third operating state is reached, the turned-on AC cooling fans are turned off according to the set shutdown order; wherein the fifth target temperature T5 is less than the first target temperature T1.

[0020] Furthermore, the method further comprises the following steps:

[0021] If the current air outlet temperature T is less than the sixth target temperature T6, and the AC cooling fan is not turned on, and reaches the fourth operating state, the turned-on DC cooling fan is turned off according to the set shutdown sequence; wherein the sixth target temperature T6 is less than the fifth target temperature T5.

[0022] Further, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; and closing the turned-on AC cooling fan according to a set closing sequence specifically includes the following steps:

[0023] Turn off the second AC cooling fan;

[0024] If the circulating air outlet temperature T is less than the seventh target temperature T7 and the fifth operating state is reached, the first AC cooling fan is turned off; wherein the sixth target temperature T6 is less than the seventh target temperature T7 and the fifth target temperature T is less than the fifth target temperature T.

[0025] Further, the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; closing the turned-on DC cooling fan according to a set closing sequence specifically includes the following steps:

[0026] Turn off the second DC cooling fan;

[0027] If the circulating air outlet temperature T is less than the eighth target temperature T8, the first DC cooling fan is turned off; wherein the eighth target temperature T8 is less than the sixth target temperature T6.

[0028] Furthermore, the method further comprises the following steps:

[0029] Calculate the difference △T between the current circulating air outlet temperature T and the preset temperature T0;

[0030] If △T is greater than the first preset temperature difference △T1, the speed of the DC fan is increased, and the larger △T is, the greater the absolute value of the increase in the speed of the DC fan is;

[0031] If ΔT is less than the first preset temperature difference ΔT2, the rotation speed of the DC fan is reduced, and the smaller ΔT is, the greater the absolute value of the reduction in the rotation speed of the DC fan is.

[0032] Furthermore, the method further comprises the following steps:

[0033] Calculate the difference △T between the current air outlet temperature T and the preset temperature T0;

[0034] If △T is greater than the first preset temperature difference △T1, the speed of the DC fan is adjusted by a first variation value X1;

[0035] If △T is less than the first preset temperature difference △T2, the speed of the DC fan is adjusted by a second variation value X2;

[0036] Among them, △T2<0<△T1, X2<0<X1.

[0037] Furthermore, the method further comprises the following steps:

[0038] If △T is greater than the third preset temperature difference △T3, the speed of the DC fan is adjusted by a third variation value X3;

[0039] If △T is less than the fourth preset temperature difference △T4, the speed of the DC fan is adjusted by a fourth variation value X4;

[0040] Among them, △T3>△T1, X3>X1, △T4<△T2, X4<X2.

[0041] Furthermore, the method further comprises the following steps:

[0042] Get the pressure of the heat pump unit;

[0043] If the obtained pressure reaches the set pressure threshold, all DC fans and AC fans are started.

[0044] Furthermore, the heat pump units include multiple sets, and at least one DC cooling fan or AC cooling fan is provided on the condenser of each heat pump unit.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. Both DC cooling fans and AC cooling fans are used to dissipate heat from the condenser of the heat pump unit, which can meet the requirements of sludge drying effect and equipment cost at the same time.

[0047] 2. Adjust the speed of the DC cooling fan according to the difference between the current air outlet temperature and the preset temperature to reduce the fluctuation of the circulating air outlet temperature and make it easier to achieve a dynamic balance of heat.

[0048] 3. Detect the pressure of the compressor unit. If the pressure of the compressor unit exceeds the set pressure threshold, start all the cooling fans to quickly reduce the pressure of the compressor unit, ensure the safe operation of the compressor unit, and prevent the compressor unit from malfunctioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of a sludge drying system in the prior art;

[0050] Figure 2 The present invention is a flowchart of a heat dissipation method for a sludge drying system in one embodiment of the present invention.

[0051] Figure 3 The present invention is a flowchart of a heat dissipation method for a sludge drying system in one embodiment of the present invention.

[0052] In the figure: A, conveyor belt; 10, compressor; 20, condenser; 30, expansion valve; 40, evaporator. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present application more clear, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0054] It should be clear that the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of the present application.

[0055] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0056] When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and do not have to be used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0057] In addition, in the description of this application, unless otherwise specified, "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0058] It should be understood that the embodiments of the present application are not limited to the precise structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the embodiments of the present application is limited only by the appended claims.

[0059] The present invention provides a heat dissipation method for a sludge drying system, wherein the sludge drying system comprises a heat pump unit and a DC heat dissipation fan and an AC heat dissipation fan corresponding to the heat pump unit; Figure 2 As shown, the method comprises the following steps:

[0060] S201: Obtaining the circulating air outlet temperature T of the sludge drying system;

[0061] S202: If the circulating air outlet temperature T> the first target temperature T1, start the DC cooling fan that is not turned on according to the set start sequence;

[0062] S203: If the circulating air outlet temperature T> the second target temperature T2, and all DC cooling fans have been turned on and reached the first operating state, then the AC cooling fans that have not been turned on are started according to the set start sequence; wherein the first target temperature T1<the second target temperature T2.

[0063] The speed of the DC heat dissipation fan can be adjusted to reduce the fluctuation of the circulating air outlet temperature T, thereby achieving a dynamic balance of heat and a better sludge drying effect, but the cost of the DC heat dissipation fan is relatively high; the speed of the AC heat dissipation fan cannot be adjusted, which will cause a large fluctuation of the circulating air outlet temperature T, so it is difficult to achieve a dynamic balance of heat, and the sludge drying effect is relatively poor, but the cost of the AC heat dissipation fan is low. In summary, the DC heat dissipation fan has better heat dissipation performance, but the cost is higher, and the AC heat dissipation fan has weaker heat dissipation performance, but the cost is lower. Therefore, in this embodiment, a DC heat dissipation fan and an AC heat dissipation fan are used simultaneously to dissipate heat from the condenser of the heat pump unit to achieve a balance between heat dissipation performance and cost, while meeting the requirements of sludge drying effect and equipment cost.

[0064] Based on the above technical solution of using both DC cooling fans and AC cooling fans to dissipate heat from the condenser, in order to reduce the fluctuation of the circulating air outlet temperature T, achieve a dynamic balance of heat, and improve the sludge drying effect, when the condenser needs to be cooled to adjust the circulating air outlet temperature T, the DC cooling fan is turned on first. If the cooling capacity of the DC cooling fan cannot meet the demand, the AC cooling fan is turned on.

[0065] Specifically, in this embodiment, if the circulating air outlet temperature T> the first target temperature T1, the unactivated DC cooling fan is started according to the set start-up sequence; if the circulating air outlet temperature T> the second target temperature T2, and the DC cooling fans are all turned on and reach the first operating state, the unactivated AC cooling fans are started according to the set start-up sequence; wherein the first target temperature T1<the second target temperature T2. In a preferred embodiment, the first target temperature T1 is equal to the preset temperature T0; in other embodiments, the first target temperature T1 may also be greater than the preset temperature T0. The preset temperature T0 is the most suitable temperature for sludge drying, which is related to factors such as the thickness of the sludge, the running speed of the conveyor belt, and the type of sludge, and can be obtained based on experimental tests. The above-mentioned second operating state may be that the activated DC fan reaches a specific speed, or the compressor reaches a specific frequency; in an optional embodiment, the first operating state is that the speed of the DC cooling fan reaches the maximum value.

[0066] In a preferred embodiment, the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; starting the unstarted DC cooling fan according to a set start sequence specifically includes the following steps:

[0067] Starting the first DC cooling fan;

[0068] If the circulating air outlet temperature T> the third target temperature T3, and the first DC cooling fan reaches the second operating state, the second DC cooling fan is started; wherein the first target temperature T1<the third target temperature T3<the second target temperature T2.

[0069] In order to achieve more accurate control of the circulating air outlet temperature T and improve the overall heat dissipation capacity of the DC cooling fan, multiple DC cooling fans can be set. When the conditions for turning on the DC cooling fan are met, each DC cooling fan is turned on in a set order. The set order can be to pre-set the numbers of each DC cooling fan and turn them on in the order of the numbers of each DC cooling fan, or to turn them on in a random order. Specifically, when the conditions for turning on the DC cooling fan are met, at least one DC cooling fan is turned on in the order of the numbers or randomly; if the heat dissipation capacity still cannot meet the heat dissipation requirements, at least one unturned DC cooling fan is turned on in the order of the numbers or randomly until all the DC cooling fans are turned on.

[0070] In this embodiment, the DC fan includes a first DC cooling fan and a second DC cooling fan; thus, the DC cooling fan that is not turned on is started according to the set start sequence, specifically including the following steps: starting the first DC cooling fan; if the circulating air outlet temperature T> the third target temperature T3, and the first DC cooling fan reaches the second operating state, it indicates that the heat dissipation capacity of the first DC cooling fan does not meet the demand, and the second DC cooling fan needs to be started; wherein the first target temperature T1<the third target temperature T3<the second target temperature T2. The above-mentioned second operating state can be that the turned-on DC fan reaches a specific speed, or the compressor reaches a specific frequency; in an optional embodiment, the second operating state is that the DC fan speed is greater than 600r / min, which is greater than the minimum speed value of the DC cooling fan and less than the maximum speed value of the DC cooling fan.

[0071] In an optional embodiment, in order to save costs, multiple DC cooling fans are electrically connected to the same speed control circuit, so the rotational speeds of the DC cooling fans that are turned on are the same; in other embodiments, multiple speed control circuits may also be set, each speed control circuit corresponds to each DC cooling fan one by one, and the rotational speed of each DC cooling fan can be adjusted individually.

[0072] In a preferred embodiment, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; starting the unstarted AC cooling fan according to a set start sequence specifically includes the following steps:

[0073] Starting the first AC cooling fan;

[0074] If the circulating air outlet temperature T>the fourth target temperature T4, the second AC cooling fan is started; wherein the fourth target temperature T4>the second target temperature T2.

[0075] In order to reduce the fluctuation of circulating air outlet temperature T caused by the start and shut down of AC fans, multiple AC cooling fans can be set. When the conditions for starting the AC cooling fans are met, each AC cooling fan is turned on in a set order. The set order can be to pre-set the numbers of each AC cooling fan and turn them on in the order of the numbers of each AC cooling fan, or to turn them on in a random order. Specifically, when the conditions for starting the AC cooling fan are met, at least one AC cooling fan is turned on in the order of the numbers or randomly; if the cooling capacity still cannot meet the cooling demand, at least one unturned AC cooling fan is turned on in the order of the numbers or randomly, until all the AC cooling fans are turned on.

[0076] In this embodiment, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; according to the set start-up order, the unstarted AC cooling fan is started, which specifically includes the following steps: starting the first AC cooling fan; if the circulating air outlet temperature T> the fourth target temperature T4, it indicates that the cooling capacity of the started AC cooling fan and the first AC cooling fan still cannot meet the demand, and the second AC cooling fan needs to be started; wherein, the fourth target temperature T4> the second target temperature T2.

[0077] In a preferred embodiment, the following steps are also included:

[0078] If the circulating air outlet temperature T is less than the fifth target temperature T5, and all DC cooling fans are turned on, and all or part of the AC cooling fans are turned on, and the third operating state is reached, the turned-on AC cooling fans are turned off according to the set shutdown order; wherein the fifth target temperature T5 is less than the first target temperature T1.

[0079] When the heat dissipation of the cooling fan is too large, the circulating air outlet temperature T will be too low, affecting the sludge drying effect. At this time, some of the cooling fans that have been turned on need to be turned off to reduce the heat dissipation and increase the air outlet temperature to a suitable range. In order to improve the energy efficiency of the fan, the AC cooling fan can be turned off first.

[0080] In this embodiment, if the circulating air outlet temperature T is less than the fifth target temperature T5, and all DC cooling fans are turned on, and all or part of the AC cooling fans are turned on, and the third operating state is reached, it indicates that the cooling capacity exceeds the demand, and the turned-on AC cooling fans need to be turned off according to the set shutdown order; wherein, the fifth target temperature T5 is less than the first target temperature T1. The third operating state can be that the DC fan reaches a specific speed, or that the compressor reaches a specific frequency, and the specific speed and frequency can be set according to the performance of the DC fan and the compressor; in an optional embodiment, the third operating state is that the speed of the DC cooling fan is less than 750r / min, which is greater than the minimum speed of the DC cooling fan and less than the maximum speed of the DC cooling fan.

[0081] In a preferred embodiment, the following steps are also included:

[0082] If the current air outlet temperature T is less than the sixth target temperature T6, and the AC cooling fan is not turned on, and reaches the fourth operating state, the turned-on DC cooling fan is turned off according to the set shutdown sequence; wherein the sixth target temperature T6 is less than the fifth target temperature T5.

[0083] When the AC cooling fan is not turned on and the heat dissipation of the cooling fan still exceeds the demand, the DC fan needs to be turned off to reduce the heat dissipation and increase the circulating air outlet temperature T.

[0084] In this embodiment, if the current air outlet temperature T is less than the sixth target temperature T6, and the AC cooling fan is not turned on, and reaches the fourth operating state, it indicates that the heat dissipation exceeds the demand, and the turned-on DC cooling fan needs to be turned off according to the set shutdown sequence; wherein the sixth target temperature T6 is less than the fifth target temperature T5. The fourth operating state can be that the DC fan reaches a specific speed, or that the compressor reaches a specific frequency, and the specific speed and frequency can be set according to the performance of the DC fan and the compressor; in an optional embodiment, the third operating state is that the DC cooling fan reaches the minimum speed.

[0085] In a preferred embodiment, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; and closing the turned-on AC cooling fan according to a set closing sequence specifically includes the following steps:

[0086] Turn off the second AC cooling fan;

[0087] If the circulating air outlet temperature T is less than the seventh target temperature T7 and the fifth operating state is reached, the first AC cooling fan is turned off; wherein the sixth target temperature T6 is less than the seventh target temperature T7 and the fifth target temperature T is less than the fifth target temperature T.

[0088] In order to achieve more accurate control of the circulating air outlet temperature T and reduce the fluctuation of the circulating air outlet temperature T, multiple AC cooling fans can be set. When the conditions for shutting down the AC fans are met, each AC cooling fan is shut down in a set order. The set order can be to pre-set the numbers of each AC cooling fan and shut down in the order of the numbers of each AC cooling fan, or to shut down each AC cooling fan in a random order. When the conditions for shutting down the AC cooling fan are met, at least one turned-on AC cooling fan is shut down in the order of the numbers or randomly; if the cooling capacity still cannot meet the cooling requirements, at least one turned-on AC cooling fan is shut down again in the order of the numbers or randomly, until all the AC cooling fans are shut down.

[0089] In this embodiment, the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; according to the set closing order, the turned-on AC cooling fan is closed, specifically including the following steps: closing the second AC cooling fan; if the circulating air outlet temperature T is less than the seventh target temperature T7, and the fifth operating state is reached, it indicates that the heat dissipation after closing the second AC cooling fan is still greater than the demand, and the first AC cooling fan needs to be closed; wherein the sixth target temperature T6 is less than the seventh target temperature T7 and the fifth target temperature T. The fifth operating state can be that the DC fan reaches a specific speed, or that the compressor reaches a specific frequency, and the specific speed and frequency can be set according to the performance of the DC fan and the compressor; in an optional embodiment, the fifth operating state is that the speed reached by the DC cooling fan is less than 500r / min.

[0090] In a preferred embodiment, the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; and closing the turned-on DC cooling fan according to a set closing sequence specifically includes the following steps:

[0091] Turn off the second DC cooling fan;

[0092] If the circulating air outlet temperature T is less than the eighth target temperature T8, the first DC cooling fan is turned off; wherein the eighth target temperature T8 is less than the sixth target temperature T6.

[0093] In order to achieve more precise control of the outlet air temperature, multiple DC cooling fans can be set. When the conditions for shutting down the DC fans are met, each DC cooling fan is shut down in a set order. The set order can be to pre-set the numbers of each DC cooling fan and shut down in the order of the numbers of each DC cooling fan, or to shut down each DC cooling fan in a random order. When the conditions for shutting down the DC cooling fan are met, at least one DC cooling fan is shut down by number or randomly; if the cooling capacity still exceeds the cooling demand, at least one DC cooling fan that is not shut down is shut down by number or randomly until all DC cooling fans are shut down.

[0094] In this embodiment, the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; the turned-on DC cooling fan is turned off according to the set shutdown order, specifically including the following steps: turning off the second DC cooling fan; if the circulating air outlet temperature T is less than the eighth target temperature T8, it indicates that the heat dissipation after turning off the second DC fan still exceeds the demand, and the first DC cooling fan needs to be turned off; wherein, the eighth target temperature T8 is less than the sixth target temperature T6.

[0095] In a preferred embodiment, the following steps are also included:

[0096] Calculate the difference △T between the current circulating air outlet temperature T and the preset temperature T0;

[0097] If △T is greater than the first preset temperature difference △T1, the speed of the DC fan is increased, and the larger △T is, the greater the absolute value of the increase in the speed of the DC fan is;

[0098] If ΔT is less than the first preset temperature difference ΔT2, the rotation speed of the DC fan is reduced, and the smaller ΔT is, the greater the absolute value of the reduction in the rotation speed of the DC fan is.

[0099] Compared with AC cooling fans, the advantage of DC cooling fans is that the speed can be adjusted. By adjusting the speed of the DC cooling fan, the circulating air outlet temperature T can also be adjusted. When the circulating air outlet temperature T is high, the speed of the DC cooling fan can be increased. When the circulating air outlet temperature T is low, the speed of the DC cooling fan can be reduced. Compared with adjusting the circulating air outlet temperature T by turning the cooling fan on and off, adjusting the circulating air outlet temperature T by adjusting the speed of the DC cooling fan will cause less fluctuation in the circulating air outlet temperature T and it is easier to achieve a dynamic balance of heat.

[0100] In this embodiment, if △T is greater than the first preset temperature difference △T1, it indicates that the current circulating air outlet temperature T is too high, and the speed of the DC fan is increased to increase the heat dissipation, and the larger the △T is, the greater the absolute value of the increase in the speed of the DC fan is, that is, the larger the △T is, the greater the adjusted speed of the DC fan is; if △T is less than the first preset temperature difference △T2, it indicates that the current circulating air outlet temperature T is too low, and the speed of the DC fan is reduced to reduce the heat dissipation, and the smaller the △T is, the greater the absolute value of the reduction in the speed of the DC fan is, that is, the smaller the △T is, the smaller the adjusted speed of the DC fan is. The speed regulation of the fan can be stepless regulation to improve the regulation accuracy, or it can be step-by-step regulation to reduce the calculation pressure of the controller.

[0101] In a preferred embodiment, the following steps are also included:

[0102] Calculate the difference △T between the current air outlet temperature T and the preset temperature T0;

[0103] If △T is greater than the first preset temperature difference △T1, the speed of the DC fan is adjusted by a first variation value X1;

[0104] If △T is less than the first preset temperature difference △T2, the speed of the DC fan is adjusted by a second variation value X2;

[0105] Among them, △T2<0<△T1, X2<0<X1.

[0106] In this embodiment, the difference △T between the circulating air outlet temperature T and the preset temperature T0 is first calculated, and then △T is compared with the preset temperature difference; if △T is greater than the first preset temperature difference △T1, it indicates that the current circulating air outlet temperature T is too high, and the speed of the DC fan needs to be adjusted by the first change value X1 to increase the speed of the DC cooling fan; if △T is less than the first preset temperature difference △T2, it indicates that the circulating air outlet temperature T is too low, and the speed of the DC fan needs to be adjusted by the second change value X2 to reduce the speed of the DC cooling fan; wherein, △T2<0<△T1, X2<0<X1.

[0107] In a preferred embodiment, the following steps are also included:

[0108] If △T is greater than the third preset temperature difference △T3, the speed of the DC fan is adjusted by a third variation value X3;

[0109] If △T is less than the fourth preset temperature difference △T4, the speed of the DC fan is adjusted by a fourth variation value X4;

[0110] Among them, △T3>△T1, X3>X1, △T4<△T2, X4<X2.

[0111] In order to adjust the outlet air temperature more quickly, multiple different preset temperature differences and corresponding speed change values ​​can be set, so that the greater the deviation between the outlet air temperature and the preset temperature T0, the greater the adjustment amount of the speed of the DC cooling fan, so that the outlet air temperature can be increased or decreased more quickly to close to the preset temperature T0.

[0112] In this embodiment, the following steps are also included: if △T is greater than the third preset temperature difference △T3, the speed of the DC fan is adjusted by a third change value X3; if △T is less than the fourth preset temperature difference △T4, the speed of the DC fan is adjusted by a fourth change value X4; wherein △T3>△T1, X3>X1, △T4<△T2, X4<X2.

[0113] In a preferred embodiment, the following steps are also included:

[0114] Get the pressure p of the heat pump unit;

[0115] If the acquired pressure p reaches the set pressure threshold p x, all DC fans and AC fans are started.

[0116] When the heat pump unit is just started, the load is too large, or the heat pump unit fails, the pressure p of the heat pump unit will be too large. Excessive pressure p of the heat pump unit will affect the safe operation of the heat pump unit and cause damage to the heat pump unit. Therefore, it is necessary to monitor the pressure p of the heat pump unit to prevent the pressure p of the heat pump unit from exceeding the set pressure threshold p. x , when the pressure p of the heat pump unit exceeds the set threshold p x When the pressure p of the heat pump unit is too low, appropriate measures should be taken to reduce the pressure p of the heat pump unit, such as increasing the speed of the cooling fan, reducing the frequency of the compressor, etc.

[0117] In this embodiment, the pressure p of the heat pump unit is first obtained, and then the obtained pressure p is compared with the set pressure threshold p x For comparison, if the pressure p reaches the set threshold p x , it indicates that the pressure p of the heat pump unit is too high, and all DC cooling fans and AC cooling fans need to be turned on to quickly discharge the heat on the condenser to reduce the pressure of the heat pump unit. Preferably, the pressure p of the heat pump unit obtained is the pressure at the compressor outlet.

[0118] In a preferred embodiment, the heat pump units include multiple sets, and at least one DC cooling fan or AC cooling fan is provided on the condenser of each heat pump unit.

[0119] Using multiple heat pump units can reduce equipment costs and improve the energy efficiency of the sludge drying system. In this embodiment, there are multiple heat pump units, and at least one DC cooling fan or AC cooling fan is provided on the condenser of each heat pump unit.

[0120] In an optional embodiment, the heat pump unit includes a first heat pump unit, a second heat pump unit, a third heat pump unit and a fourth heat pump unit, wherein the model of the first heat pump unit and the second heat pump unit is R410A, which is suitable for the working condition with relatively low condensation and evaporation temperature, and the model of the third heat pump unit and the fourth heat pump unit is R134A, which is suitable for the condition with relatively low condensation and evaporation temperature, and the overall energy efficiency ratio of the heat pump unit is improved by the cooperation of the two heat pump units; the DC heat dissipation fan includes a first DC heat dissipation fan and a second DC heat dissipation fan, and the AC heat dissipation fan includes a first AC heat dissipation fan and a second AC heat dissipation fan, the first DC heat dissipation fan is arranged on the first heat pump unit, the second DC heat dissipation fan is arranged on the third heat pump unit, the first AC heat dissipation fan is arranged on the second heat pump unit, and the second AC heat dissipation fan is arranged on the fourth heat pump unit. In other embodiments, each heat pump unit may also be of the same model.

[0121] In a preferred embodiment, the sludge drying system includes a first heat pump unit, a second heat pump unit, a third heat pump unit, a fourth heat pump unit, a first DC cooling fan, a second DC cooling fan, a first AC cooling fan, and a second AC cooling fan. The first DC cooling fan is arranged on the first heat pump unit, the second DC cooling fan is arranged on the third heat pump unit, the first AC cooling fan is arranged on the second heat pump unit, and the second AC cooling fan is arranged on the fourth heat pump unit; Figure 3 As shown, the heat dissipation method of the sludge drying system specifically includes the following steps:

[0122] S301: Obtaining the circulating air outlet temperature T of the sludge drying system and the pressure p of the heat pump unit;

[0123] S302: If the circulating air outlet temperature T> the first target temperature T1, start the DC cooling fan that is not turned on according to the set start sequence;

[0124] S303: If the circulating air outlet temperature T> the second target temperature T2, and the DC cooling fans are all turned on and reach the first operating state, the AC cooling fans that are not turned on are started according to the set start sequence; wherein the first target temperature T1<the second target temperature T2;

[0125] S304: If the circulating air outlet temperature T is less than the fifth target temperature T5, and all DC cooling fans are turned on, and all or part of the AC cooling fans are turned on, and the third operating state is reached, the turned-on AC cooling fans are turned off according to the set closing order; wherein the fifth target temperature T5 is less than the first target temperature T1;

[0126] S305: If the current air outlet temperature T is less than the sixth target temperature T6, and the AC cooling fan is not turned on, and the fourth operating state is reached, the turned-on DC cooling fan is turned off according to the set closing sequence; wherein the sixth target temperature T6 is less than the fifth target temperature T5;

[0127] S306: Calculate the difference ΔT between the current air outlet temperature T and the preset temperature T0;

[0128] S307: If ΔT is greater than the first preset temperature difference ΔT1, the speed of the DC fan is adjusted by a first variation value X1; wherein ΔT1>0, X1>0;

[0129] S308: If ΔT is less than the first preset temperature difference ΔT2, the speed of the DC fan is adjusted by a second variation value X2; wherein ΔT2<0, X2<0;

[0130] S309: If ΔT is greater than a third preset temperature difference ΔT3, the speed of the DC fan is adjusted by a third variation value X3; wherein ΔT3>ΔT1, X3>X1;

[0131] S310: If ΔT is less than a fourth preset temperature difference ΔT4, the speed of the DC fan is adjusted by a fourth variation value X4; wherein ΔT4<ΔT2, X4<X2;

[0132] S311: If the acquired pressure p reaches the set pressure threshold p x , all DC fans and AC fans are started.

[0133] In the above step S302, starting the DC cooling fan that is not turned on according to the set start sequence specifically includes the following steps:

[0134] Starting the first DC cooling fan;

[0135] If the circulating air outlet temperature T> the third target temperature T3, and the first DC cooling fan reaches the second operating state, the second DC cooling fan is started; wherein the first target temperature T1<the third target temperature T3<the second target temperature T2.

[0136] In the above step S303, the AC cooling fan that is not turned on is started according to the set start sequence, which specifically includes the following steps:

[0137] Starting the first AC cooling fan;

[0138] If the circulating air outlet temperature T>the fourth target temperature T4, the second AC cooling fan is started; wherein the fourth target temperature T4>the second target temperature T2.

[0139] In the above step S304, the turned-on AC cooling fan is turned off according to the set closing order, which specifically includes the following steps:

[0140] Turn off the second AC cooling fan;

[0141] If the circulating air outlet temperature T is less than the seventh target temperature T7 and the fifth operating state is reached, the first AC cooling fan is turned off; wherein the sixth target temperature T6 is less than the seventh target temperature T7 and the fifth target temperature T is less than the fifth target temperature T.

[0142] In the above step S305, the turned-on DC cooling fans are turned off according to the set closing order, which specifically includes the following steps:

[0143] Turn off the second DC cooling fan;

[0144] If the circulating air outlet temperature T is less than the eighth target temperature T8, the first DC cooling fan is turned off; wherein the eighth target temperature T8 is less than the sixth target temperature T6.

[0145] Compared with the prior art, the present invention has the following beneficial effects:

[0146] 1. Both DC cooling fans and AC cooling fans are used to dissipate heat from the condenser of the heat pump unit, which can meet the requirements of sludge drying effect and equipment cost at the same time.

[0147] 2. Adjust the speed of the DC cooling fan according to the difference between the current air outlet temperature and the preset temperature to reduce the fluctuation of the circulating air outlet temperature and make it easier to achieve a dynamic balance of heat.

[0148] 3. Detect the pressure of the compressor unit. If the pressure of the compressor unit exceeds the set pressure threshold, start all the cooling fans to quickly reduce the pressure of the compressor unit, ensure the safe operation of the compressor unit, and prevent the compressor unit from malfunctioning.

[0149] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A heat dissipation method for a sludge drying system, It is characterized in that The sludge drying system includes a heat pump unit, and a DC cooling fan and an AC cooling fan corresponding to the heat pump unit; wherein the DC cooling fan includes a first DC cooling fan and a second DC cooling fan; the AC cooling fan includes a first AC cooling fan and a second AC cooling fan; The method comprises the following steps: Obtaining the circulating air outlet temperature T of the sludge drying system; If the circulating air outlet temperature T> the first target temperature T 1 , then start the unstarted DC cooling fan according to the set start sequence, which specifically includes the following steps: Starting the first DC cooling fan; If the circulating air outlet temperature T> the third target temperature T 3 , and the first DC cooling fan reaches the second operating state, starting the second DC cooling fan; If the circulating air outlet temperature T> the second target temperature T 2 , and the DC cooling fans have all been turned on and have reached the first operating state, then the AC cooling fans that have not been turned on are started according to the set start sequence, which specifically includes the following steps: Starting the first AC cooling fan; If the circulating air outlet temperature T> the fourth target temperature T 4 , then start the second AC cooling fan; If the circulating air outlet temperature T is less than the fifth target temperature T 5 , and all DC cooling fans have been turned on, and all or part of the AC cooling fans have been turned on, and the third operating state is reached, then the turned-on AC cooling fans are turned off according to the set shutdown sequence; if the current air outlet temperature T< the sixth target temperature T 6 , and the AC cooling fan is not turned on, and reaches the fourth operating state, then turn off the turned-on DC cooling fan according to the set shutdown sequence; Among them, the sixth target temperature T 6 <Fifth target temperature T 5 <First target temperature T 1 <Third target temperature T 3 <Second target temperature T 2 <Fourth target temperature T 4 ; Among them, the first operating state is that the speed of the DC cooling fan reaches the maximum speed value; the second operating state is that the speed of the DC fan is greater than 600r / min, which is greater than the minimum speed value of the DC cooling fan and less than the maximum speed value of the DC cooling fan; the third operating state is that the speed of the DC cooling fan is less than 750r / min, which is greater than the minimum speed of the DC cooling fan and less than the maximum speed of the DC cooling fan; the fourth operating state is that the DC cooling fan reaches the minimum speed.

2. The heat dissipation method of the sludge drying system according to claim 1, It is characterized in that According to the set shutdown sequence, turn off the AC cooling fan that has been turned on. The following steps are involved: Turn off the second AC cooling fan; If the circulating air outlet temperature T is less than the seventh target temperature T 7 , and reaches the fifth operating state, the first AC cooling fan is turned off; wherein the sixth target temperature T 6 <Seventh target temperature T 7 <Fifth target temperature T 5 ; Wherein, the fifth operating state is that the rotation speed reached by the DC cooling fan is less than 500r / min.

3. The heat dissipation method of the sludge drying system according to claim 2, It is characterized in that According to the set shutdown sequence, turn off the turned-on DC cooling fan, which includes the following steps: Turn off the second DC cooling fan; If the circulating air outlet temperature T is less than the eighth target temperature T 8 , then turn off the first DC cooling fan; wherein the eighth target temperature T 8 <Sixth target temperature T 6 .

4. The heat dissipation method of the sludge drying system according to any one of claims 1 to 3, further comprising: The following steps are involved: Calculate the current circulating air outlet temperature T and the preset temperature T 0 The difference △T; If △T is greater than the first preset temperature difference △T 1 , then the speed of the DC fan is increased, and the larger △T is, the greater the absolute value of the increase in the speed of the DC fan is; If △T is less than the second preset temperature difference △T 2 , the speed of the DC fan is reduced, and the smaller △T is, the greater the absolute value of the speed reduction of the DC fan is.

5. The heat dissipation method of the sludge drying system according to any one of claims 1 to 3, further comprising: The following steps are involved: Calculate the current circulating air outlet temperature T and the preset temperature T 0 The difference △T; If △T is greater than the first preset temperature difference △T 1 , then adjust the speed of the DC fan to the first change value X 1 ; Among them, △T 1 >0,X 1 >0; If △T is less than the second preset temperature difference △T 2 , then adjust the speed of the DC fan to the second variable value X 2 ; Among them, △T 2 <0, X 2 <0.

6. The heat dissipation method of the sludge drying system according to claim 5, further comprising: The following steps are involved: If △T is greater than the third preset temperature difference △T 3 , then adjust the speed of the DC fan to the third variable value X 3 ; Among them, △T 3 >△T 1 , X 3 >X 1 ; If △T is less than the fourth preset temperature difference △T 4 , then the speed of the DC fan is adjusted to the fourth variable value X 4 ; Among them, △T 4 <△T 2 , X 4 <X 2 .

7. The heat dissipation method of the sludge drying system according to any one of claims 1 to 3, further comprising: The following steps are involved: Get the pressure p of the heat pump unit; If the acquired pressure reaches the set pressure threshold p x , all DC fans and AC fans are started.

8. The heat dissipation method of the sludge drying system according to any one of claims 1 to 3, Features: The heat pump unit includes multiple sets.

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