A bidirectional temperature control method for controlling temperature of liquid in a feeding tank

Abstract

The application provides a kind of temperature control method of bidirectional temperature control feed tank liquid, comprising: the heating steam pipeline and heat dissipation steam pipeline are connected to the sealing interlayer of feed tank, the heating steam pipeline is equipped with steam film valve, first quick on-off valve and first mass flowmeter, the heat dissipation steam pipeline is equipped with second quick on-off valve and second mass flowmeter;Judge whether there is liquid in feed tank, if so, obtain the total weight of liquid in tank and actual liquid temperature;The total mass of steam entering interlayer is obtained by the first mass flowmeter and the second mass flowmeter, and the corresponding steam heat is calculated according to the total mass of steam;According to the actual liquid temperature and the steam heat, the opening of the steam film valve, the first quick on-off valve and / or the second quick on-off valve is adjusted, and the temperature control of feed tank liquid is carried out.The application can improve the stability and accuracy of liquid temperature control.

Description

Technical Field

[0001] This invention relates to the field of feed liquid temperature control technology in silk making, and in particular to a bidirectional temperature control method for feed liquid temperature control in a feed tank. Background Technology

[0002] The tobacco processing feeder is a device used in the tobacco processing industry to atomize tobacco sheets and add liquid feed. The feed tank's function is to store the liquid feed and maintain a constant temperature. The tank temperature is collected by a temperature sensor and controlled by the opening and closing of a steam on / off valve. Steam enters the sealed jacket around the tank, indirectly heating the liquid feed using the heat from the tank wall. When there is a large amount of liquid feed in the tank, the heating process is relatively slow. When there is a small amount of liquid feed, heating is rapid, which can easily lead to overheating. Current feeding tank temperature control uses a single steam on / off valve: the valve closes when the tank temperature is above 55°C and opens when the temperature is below 54°C. This temperature control model has a flaw: at the end of production, when the remaining liquid feed is small, the large amount of steam entering after opening the steam on / off valve will continuously heat the small amount of liquid feed, causing temperature fluctuations at the end of the batch, leading to overheating and affecting product quality. Meanwhile, the valve's opening and closing determines the amount of steam added, and all the heat from the steam is transferred to the tank and the feed liquid, while excess heat is stored on the steam pipe wall of the tank and cannot be dissipated. This means that the temperature control of the feed liquid in the tank can only be rapid heating, not rapid cooling. However, current process requirements for the chemical properties of the feed liquid stipulate that it cannot exceed the set temperature and must remain stable within a small range of the process temperature setting. Therefore, achieving a dual-function feed liquid temperature control that can both rapidly heat and rapidly dissipate heat, thus achieving stable temperature control, is of great significance. Summary of the Invention

[0003] This invention provides a bidirectional temperature control method for the feeding tank liquid temperature, which solves the problems existing in the temperature control of the feeding tank liquid in the current silk making process. It can realize rapid heating and rapid heat dissipation of the tank, and improve the stability and accuracy of the liquid temperature control.

[0004] To achieve the following objectives, the present invention provides the following technical solutions:

[0005] A method for controlling the temperature of liquid in a feeding tank with bidirectional temperature control, comprising:

[0006] The sealing jacket of the feeding tank is connected to a heating steam pipeline and a cooling steam pipeline. The heating steam pipeline is used to supply steam into the sealing jacket of the feeding tank to heat the liquid in the feeding tank. The cooling steam pipeline is used to discharge excess steam from the insulation layer of the pipe wall.

[0007] The heating steam pipeline is equipped with a steam diaphragm valve, a first quick-on / off valve and a first mass flow meter, and the heat dissipation steam pipeline is equipped with a second quick-on / off valve and a second mass flow meter.

[0008] Determine if there is liquid in the feeding tank. If so, obtain the total weight of the liquid in the tank and the actual temperature of the liquid.

[0009] The total mass of steam entering the interlayer is obtained through the first mass flow meter and the second mass flow meter, and the corresponding steam heat is calculated based on the total mass of steam.

[0010] The opening degree of the steam diaphragm valve, the first quick-on / off valve, and / or the second quick-on / off valve is adjusted according to the actual liquid temperature and the steam heat to control the temperature of the liquid in the feeding tank.

[0011] Preferably, the step of calculating the corresponding steam heat based on the total steam mass includes:

[0012] Based on the steam heat equation, the formula for the conservation of steam heat energy is obtained: The corresponding steam heat is calculated, where T1 is the temperature of the liquid before absorbing heat, T2 is the temperature of the liquid after absorbing heat, k, G, and c are constants obtained through experiments, Y is the total mass of the liquid in the tank, M is the total mass of steam, and t is time.

[0013] Preferred options also include:

[0014] The tank is divided into zones based on the total weight of the liquid, and a correspondence is established between the opening value of the steam diaphragm valve and the total weight of the liquid. The steam pressure is then controlled based on the temperature of the liquid in the tank to improve the accuracy of temperature control.

[0015] Preferably, the step of dividing the tank according to the total weight of the liquid in the tank includes:

[0016] A first weight threshold weight1, a second weight threshold weight2, and a third weight threshold weight3 are established. The total weight of the liquid in the tank is determined to be in the corresponding zone, and the opening value of the corresponding steam diaphragm valve is calculated, where weight3 < weight2 < weight1.

[0017] Preferably, the relationship between the opening value of the steam diaphragm valve and the total weight of the liquid is constructed by:

[0018] The opening value Va of the steam diaphragm valve is calculated using the following formula:

[0019] Where R is the set opening value;

[0020] Preferred options also include:

[0021] The opening time TON2 and closing time TOFF2 of the first quick-on / off valve are calculated based on the actual temperature Tt of the liquid. Then, the first quick-on / off valve is repeatedly opened and closed with varying times. The opening time TON2 and closing time TOFF2 are recalculated each time. Finally, the opening and closing of the first quick-on / off valve are controlled by a time-varying pulse wave to stabilize the temperature of the liquid in the tank to the process set value Ttemp.

[0022] Preferred options also include:

[0023] If the actual temperature of the feed liquid, Tt, is greater than the process setting value, the second quick-on / off valve is kept open, and the steam diaphragm valve and the first quick-on / off valve of the heating pipeline are closed to quickly dissipate heat.

[0024] Preferred options also include:

[0025] when When the actual temperature of the liquid in the tank is close to the process requirement, in order to prevent overheating, the steam diaphragm valve and the first quick-on / off valve of the heating pipeline are closed, and the first quick-on / off valve and the second quick-on / off valve are opened and closed in a timed manner. Then, the first quick-on / off valve and the second quick-on / off valve are repeatedly opened and closed in a timed manner, and finally the opening and closing of the second quick-on / off valve is controlled in the form of a fixed value pulse wave.

[0026] Preferred options also include:

[0027] when If the first quick-on / off valve controls the heating process too rapidly, and the ratio of temperature rise to time is greater than the set threshold YU2, then the steam diaphragm valve and the first quick-on / off valve in the heating pipeline are closed, and then according to... The opening time TON4 and closing time TOFF4 of the second quick-on / off valve are calculated based on the cumulative steam amount added by the first mass flow meter. Then, the second quick-on / off valve is repeatedly opened and closed with varying times. The opening time TON4 and closing time TOFF4 are recalculated each time. Finally, the opening and closing of the second quick-on / off valve are controlled in the form of time-varying pulse waves to slow down the rate at which the liquid temperature rises too quickly, thereby ensuring that the liquid temperature does not rise too quickly and cause overheating.

[0028] Preferred options also include:

[0029] After the second quick-acting valve in the cooling steam pipeline is opened, the opening time TON4 is accumulated until the total mass flow meter of the cooling steam pipeline reaches a value X. Then, the second quick-acting valve is quickly closed. The formula for calculating the value X is: ,in Defined as a proportional coefficient, determined by user debugging, P1 is the cumulative steam amount added by the first mass flow meter.

[0030] This invention provides a bidirectional temperature control method for the liquid temperature of a feeding tank. The method uses the total weight of steam entering the tank and the actual liquid temperature to adjust the opening of the steam diaphragm valve, the first quick-on / off valve, and the second quick-on / off valve on the heating steam pipeline and the heat dissipation heating pipeline connected to the feeding tank. This controls the liquid temperature in the feeding tank, solving the problems existing in the temperature control of liquid in existing silk-making feeding tanks. It enables rapid heating and rapid heat dissipation of the tank, improving the stability and accuracy of liquid temperature control. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0032] Figure 1 This is a schematic diagram of a method for controlling the temperature of liquid in a feeding tank using a dual-diaphragm valve linkage control system, provided by the present invention.

[0033] Figure 2 This is a schematic diagram of a feeding tank equipped with dual steam pipelines for heating and cooling, provided in an embodiment of the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the embodiments of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and implementation methods.

[0035] To address the problems existing in the temperature control of the feed liquid in existing silk-making feeding tanks, this invention provides a bidirectional temperature control method for the feed liquid in feeding tanks. This method solves the problems existing in the temperature control of the feed liquid in existing silk-making feeding tanks, and enables rapid heating and cooling of the tank, thereby improving the stability and accuracy of the feed liquid temperature control.

[0036] like Figure 1 As shown, a method for controlling the temperature of liquid in a feeding tank with bidirectional temperature control includes:

[0037] S1: The sealing jacket of the feeding tank is connected to a heating steam pipe and a cooling steam pipe. The heating steam pipe is used to supply steam to the sealing jacket of the feeding tank to heat the liquid in the feeding tank. The cooling steam pipe is used to discharge excess steam in the insulation layer of the pipe wall.

[0038] S2: The heating steam pipeline is equipped with a diaphragm valve, a first quick-on / off valve and a first mass flow meter, and the heat dissipation steam pipeline is equipped with a second quick-on / off valve and a second mass flow meter.

[0039] S3: Determine whether there is liquid in the feeding tank. If so, obtain the total weight of the liquid in the tank and the actual temperature of the liquid.

[0040] S4: The total mass of steam entering the interlayer is obtained through the first mass flow meter and the second mass flow meter, and the corresponding steam heat is calculated based on the total mass of steam.

[0041] S5: Adjust the opening degree of the steam diaphragm valve, the first quick-on / off valve and / or the second quick-on / off valve according to the actual liquid temperature and the steam heat to control the temperature of the liquid in the feeding tank.

[0042] Specifically, in one embodiment, such as Figure 2 As shown, the feeding tank is equipped with dual steam lines for heating and cooling. The heating steam line is used to add steam and requires a quick-on / off valve Y1 (on / off control), a steam diaphragm valve Y2 (percentage opening control), a steam mass flow meter P1, and other necessary components. The cooling steam line is used to discharge excess steam from the insulation layer of the pipe wall and is also equipped with a quick-on / off valve Y3 (on / off control), a steam mass flow meter P2, and other necessary components. This method provides a cooling steam line that can intelligently and selectively control the cooling process based on the tank temperature. Especially when the tank temperature rises too rapidly, it can perform formula-based constant total mass steam discharge control based on the total mass of added steam, ultimately achieving dual-function temperature control of the feed liquid that can both rapidly heat and rapidly cool.

[0043] Furthermore, the calculation of the corresponding steam heat based on the total steam mass includes:

[0044] Based on the steam heat equation, the formula for the conservation of steam heat energy is obtained: The corresponding steam heat is calculated, where T1 is the temperature of the liquid before absorbing heat, T2 is the temperature of the liquid after absorbing heat, k, G, and c are constants obtained through experiments, Y is the total mass of the liquid in the tank, M is the total mass of steam, and t is time.

[0045] A simplified heat equation is established using a steam mass flow meter, as follows:

[0046] Assuming the steam in the feeder remains at a constant mass, meaning the steam temperature and pressure remain stable, and assuming the feed liquid temperature is maintained at the same reference temperature during the test, the steam heat Q can be considered directly proportional to the steam flow rate mass F. Assuming a proportionality constant k, integrating F over time t yields the cumulative total mass M of the steam mass flow meter.

[0047] The steam heat consumption Q mainly considers three parts. The first part, Q1, is the heat absorption of mechanical parts. Due to the good sealing of the steam pipe wall in the tank, this part can be approximated as the product of a constant qa and time t. The second part, Q2, is the heat dissipation of mechanical parts and the heat loss of the pipeline. This part can also be approximated as the product of a constant qb and time t. The third part, Q3, is the heat absorption of the liquid material, which is the main factor in controlling the temperature of the liquid material. According to the formula for the temperature rise due to heat absorption by the liquid material: Q=cm(t2-t1), assuming that the specific heat value of each liquid material is equal, it can be concluded that the heat absorption of the liquid material is directly proportional to the product of the mass Y value of the liquid material and the temperature difference (t2-t1). Here, T1 and T2 represent the temperatures of the liquid material before and after heat absorption.

[0048] Therefore, the energy conservation formula for steam heat can be simplified to:

[0049] ;

[0050] After combining them, we get: ;make G is a constant. The equation then simplifies further to: The values ​​of k, G, and c in the above equations are constants and need to be determined through experimental connections.

[0051] In one embodiment, such as Figure 2 As shown, due to the limitation of the equation's applicability requiring the feed liquid temperature to be at the same reference temperature for testing, the feed liquid must be at the same temperature value before the test. The test method is as follows: With the heating steam pipeline's quick-start valve Y1 closed, slowly open the steam diaphragm valve Y2 to 100%. Then, switch the quick-start valve Y1 on and off in a timed manner, ensuring the opening time of the quick-start valve Y1 is a fixed value TON1 and the closing time is a fixed value TFF1. Repeatedly open and close the quick-start valve Y1 in a timed manner, finally controlling the opening and closing of the quick-start valve Y1 with a fixed-value pulse wave, so that the feed liquid temperature in the tank stabilizes to the process set value Ttemp minus the temperature threshold YU1, i.e., using a fixed-value pulse wave to control the feed liquid temperature to near the value of (Ttemp - YU1). Then, three tests are conducted, and the test data is obtained. The equations obtained are:

[0052] ;

[0053] The values ​​of k, G, and c are obtained by solving the system of equations.

[0054] The formula for obtaining the value of M is: ;

[0055] Based on thermodynamics and modeling characteristics, the formula is applicable within a small ±1 / ±1°C range of the feed liquid temperature process setpoint Ttemp. In this invention, ±5°C is used, meaning the formula's applicable range is... .

[0056] The method also includes:

[0057] The tank is divided into zones based on the total weight of the liquid, and a correspondence is established between the opening value of the steam diaphragm valve and the total weight of the liquid. The steam pressure is then controlled based on the temperature of the liquid in the tank to improve the accuracy of temperature control.

[0058] Furthermore, the step of dividing the tank into zones based on the total weight of the liquid contents includes:

[0059] A first weight threshold weight1, a second weight threshold weight2, and a third weight threshold weight3 are established to determine the zone in which the total weight of the liquid in the tank is located, and the opening value of the corresponding steam diaphragm valve is calculated, where weight3 < weight2 < weight1.

[0060] Furthermore, constructing the correspondence between the opening value of the steam diaphragm valve and the total weight of the feed liquid includes:

[0061] The opening value Va of the steam diaphragm valve is calculated using the following formula:

[0062] Where R is the set opening value.

[0063] In an embodiment, such as Figure 2 As shown, in the precise temperature control of the liquid in the new tobacco feeding tank, the percentage adjustment of the steam diaphragm valve opening effectively reduces steam pressure. If the liquid level is high, the Y value is large, resulting in a large steam diaphragm valve opening. This means less steam pressure reduction is needed, and more steam enters under the same conditions. Conversely, if the liquid level is low, the Y value is small, resulting in a small steam diaphragm valve opening. This requires steam pressure reduction, and less steam enters under the same conditions. When the steam diaphragm valve opening is less than R%, the steam pressure is too low to achieve a good heating effect. Therefore, the minimum effective opening value is used in the weight 3 to weight 2 range.

[0064] The method further includes: calculating the opening time TON2 and closing time TOFF2 of the first quick-on / off valve based on the actual value Tt of the liquid temperature, and then repeatedly opening and closing the first quick-on / off valve in a variable time manner, recalculating the values ​​of the opening time TON2 and closing time TOFF2 each time, and finally controlling the opening and closing of the first quick-on / off valve in the form of a time-varying pulse wave, so that the liquid temperature in the tank is stabilized to the process set value Ttemp.

[0065] Specifically, when When the actual temperature of the feed liquid, Tt, is close to the process setpoint, Ttemp, two time-varying pulse waves are used to reach the process setpoint, with each pulse increasing the temperature by [missing information]. The time period of each time-varying pulse wave is controlled by time1. Since the temperature difference is small, to prevent overheating due to rapid temperature rise, it is not necessary to approach the target value quickly; therefore, the time1 value is set relatively large. From the above formula, we can derive:

[0066] ;

[0067] The control method is as follows: First, zero out the total accumulated mass of the steam mass flow meter P1 in the heating steam pipeline. Then, adjust the opening value of the steam diaphragm valve Y2 in the heating steam pipeline according to the percentage obtained from the Va formula above. Keep the quick-on / off valve Y3 in the heat dissipation steam pipeline closed, and open the quick-on / off valve Y1 in the heating steam pipeline. Start accumulating the time TON2 until the total accumulated mass of the steam mass flow meter P1 in the heating steam pipeline reaches the M value. Then, quickly close the quick-on / off valve Y1. Calculate the time TON2 using a timer. The time TOFF2 for keeping the quick-on / off valve Y1 closed can be calculated using the formula: .

[0068] After the closing time TOFF2 of the quick-on / off valve Y1 is reached, the M value is recalculated, and the quick-on / off valve Y1 is opened again until the accumulated amount on the P1 meter reaches the new M value. Then Y1 is closed again, and the closing time is kept at the newly calculated TOFF2 value.

[0069] when If the actual temperature of the feed liquid, Tt, deviates from the process setpoint, Ttemp, then three time-varying pulse waves are used to reach the process setpoint, with each pulse increasing the temperature by a certain amount. The time period of each time-varying pulse wave is controlled by time2. Due to the large temperature difference, it needs to approach the target value quickly, so time2 is set to be less than time1. Therefore, the following can be derived from the above formula:

[0070] ;

[0071] The time TOFF2 for keeping the fast on / off valve Y1 closed can be calculated using the formula: .

[0072] After the closing time TOFF2 of the quick-on / off valve Y1 is reached, the M value is recalculated, and the quick-on / off valve Y1 is opened again until the accumulated amount on the P1 meter reaches the new M value. Then Y1 is closed again, and the closing time is kept at the newly calculated TOFF2 value.

[0073] when If the actual temperature of the feed liquid, Tt, deviates significantly from the process setpoint, Ttemp, then four time-varying pulse waves are used to reach the process setpoint, with each pulse increasing the temperature by [missing information]. The time period of each time-varying pulse wave is controlled to be time3. Due to the large temperature difference, it needs to approach the target value very quickly; therefore, time3 is set to be less than time2. From the above formula, we can derive:

[0074] ;

[0075] The time TOFF2 for keeping the fast on / off valve Y1 closed can be calculated using the formula: .

[0076] After the closing time TOFF2 of the quick-on / off valve Y1 is reached, the M value is recalculated, and the quick-on / off valve Y1 is opened again until the accumulated amount on the P1 meter reaches the new M value. Then Y1 is closed again, and the closing time is kept at the newly calculated TOFF2 value.

[0077] The method further includes: if the actual temperature of the feed liquid Tt is greater than the process setting value, then the second quick-on / off valve is kept open, and the steam film valve and the first quick-on / off valve of the heating pipeline are closed to quickly dissipate heat.

[0078] The method also includes: when When the actual temperature of the liquid in the tank is close to the process requirement, in order to prevent overheating, the steam diaphragm valve and the first quick-on / off valve of the heating pipeline are closed, and the first quick-on / off valve and the second quick-on / off valve are opened and closed in a timed manner. Then, the first quick-on / off valve and the second quick-on / off valve are repeatedly opened and closed in a timed manner, and finally the opening and closing of the second quick-on / off valve is controlled in the form of a fixed value pulse wave.

[0079] The method also includes: when If the first quick-on / off valve controls the heating process too rapidly, and the ratio of temperature rise to time is greater than the set threshold YU2, then the steam diaphragm valve and the first quick-on / off valve in the heating pipeline are closed, and then according to... The opening time TON4 and closing time TOFF4 of the second quick-on / off valve are calculated based on the cumulative steam amount added by the first mass flow meter. Then, the second quick-on / off valve is repeatedly opened and closed with varying times. The opening time TON4 and closing time TOFF4 are recalculated each time. Finally, the opening and closing of the second quick-on / off valve are controlled in the form of time-varying pulse waves to slow down the rate at which the liquid temperature rises too quickly, thereby ensuring that the liquid temperature does not rise too quickly and cause overheating.

[0080] The method further includes: after the second quick-on / off valve of the heat dissipation steam pipeline is opened, the opening time TON4 is accumulated until the total accumulated mass of the second mass flow meter of the heat dissipation steam pipeline reaches a value X, then the second quick-on / off valve is quickly closed, wherein the formula for calculating the value X is: ,in Defined as a proportional coefficient, determined by user debugging, P1 is the cumulative steam amount added by the first mass flow meter.

[0081] The time period control length of each time-varying pulse wave is time4, which is determined by the user through debugging. Therefore, the formula for the shutdown time TOFF4 can be derived as follows:

[0082] .

[0083] As can be seen, the present invention provides a bidirectional temperature control method for the liquid temperature of a feeding tank. The method uses the total weight of steam entering the tank and the actual liquid temperature to adjust the opening of the steam diaphragm valve, the first quick-on / off valve, and the second quick-on / off valve on the heating steam pipeline and the heat dissipation heating pipeline connected to the feeding tank, so as to control the liquid temperature in the feeding tank. This solves the problems existing in the temperature control of the liquid in the existing silk feeding tank, and can realize rapid heating and rapid heat dissipation of the tank, thereby improving the stability and accuracy of the liquid temperature control.

[0084] The structure, features, and effects of the present invention have been described in detail above with reference to the embodiments shown in the figures. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall be within the protection scope of the present invention as long as they do not exceed the spirit covered by the specification and figures.

Claims

1. A method for controlling the temperature of liquid in a feeding tank with bidirectional temperature control, characterized in that, include: The sealing jacket of the feeding tank is connected to a heating steam pipeline and a cooling steam pipeline. The heating steam pipeline is used to supply steam into the sealing jacket of the feeding tank to heat the liquid in the feeding tank. The cooling steam pipeline is used to discharge excess steam from the insulation layer of the pipe wall. The heating steam pipeline is equipped with a steam diaphragm valve, a first quick-on / off valve and a first mass flow meter, and the heat dissipation steam pipeline is equipped with a second quick-on / off valve and a second mass flow meter. Determine if there is liquid in the feeding tank. If so, obtain the total weight of the liquid in the tank and the actual temperature of the liquid. The total mass of steam entering the interlayer is obtained through the first mass flow meter and the second mass flow meter, and the corresponding steam heat is calculated based on the total mass of steam. The opening degree of the steam diaphragm valve, the first quick-on / off valve, and / or the second quick-on / off valve is adjusted according to the actual liquid temperature and the steam heat to control the temperature of the liquid in the feeding tank. The calculation of the corresponding steam heat based on the total steam mass includes: Based on the steam heat equation, the formula for the conservation of steam heat energy is obtained: The corresponding steam heat is calculated, where T1 is the temperature of the liquid before absorbing heat, T2 is the temperature of the liquid after absorbing heat, k, G, and c are constants obtained through experiments, Y is the total mass of the liquid in the tank, M is the total mass of steam, and t is time. The method also includes: The tank is divided into zones based on the total weight of the liquid material, and a correspondence is established between the opening value of the steam diaphragm valve and the total weight of the liquid material. In this way, the steam pressure is controlled based on the temperature of the liquid material in the tank to improve the temperature control accuracy. The step of dividing the tank into zones based on the total weight of the liquid in the tank includes: A first weight threshold weight1, a second weight threshold weight2, and a third weight threshold weight3 are established to determine the total weight of the liquid in the tank within the corresponding zone, so as to calculate the opening value of the corresponding steam diaphragm valve, where weight3 < weight2 < weight1; Constructing the relationship between the opening value of the steam diaphragm valve and the total weight of the liquid feed includes: The opening value Va of the steam diaphragm valve is calculated using the following formula: Where R is the set opening value; The method also includes: The opening time TON2 and closing time TOFF2 of the first quick-on / off valve are calculated based on the actual temperature Tt of the liquid. Then, the first quick-on / off valve is repeatedly opened and closed in a variable time manner. The opening time TON2 and closing time TOFF2 are recalculated each time. Finally, the opening and closing of the first quick-on / off valve are controlled in the form of time-varying pulse waves, so that the temperature of the liquid in the tank is stabilized to the process set value Ttemp. when If the first quick-on / off valve controls the heating process too rapidly, and the ratio of temperature rise to time is greater than the set threshold YU2, then the steam diaphragm valve and the first quick-on / off valve in the heating pipeline are closed, and then according to... The opening time TON4 and closing time TOFF4 of the second quick-on / off valve are calculated based on the cumulative steam amount added by the first mass flow meter. Then, the second quick-on / off valve is repeatedly opened and closed with varying times. The opening time TON4 and closing time TOFF4 are recalculated each time. Finally, the opening and closing of the second quick-on / off valve are controlled in the form of time-varying pulse waves to slow down the rate at which the liquid temperature rises too quickly, thereby ensuring that the liquid temperature does not rise too quickly and cause overheating.

2. The method for controlling the temperature of liquid in a feeding tank with bidirectional temperature control according to claim 1, characterized in that, Also includes: If the actual temperature of the feed liquid, Tt, is greater than the process setting value, the second quick-on / off valve is kept open, and the steam diaphragm valve and the first quick-on / off valve of the heating pipeline are closed to quickly dissipate heat.

3. The bidirectional temperature control method for the feed tank liquid temperature according to claim 2, characterized in that, Also includes: when When the actual temperature of the liquid in the tank is close to the process requirement, in order to prevent overheating, the steam diaphragm valve and the first quick-on / off valve of the heating pipeline are closed, and the first quick-on / off valve and the second quick-on / off valve are opened and closed in a timed manner. Then, the first quick-on / off valve and the second quick-on / off valve are repeatedly opened and closed in a timed manner, and finally the opening and closing of the second quick-on / off valve is controlled in the form of a fixed value pulse wave.

4. The bidirectional temperature control method for the feed tank liquid temperature according to claim 3, characterized in that, Also includes: After the second quick-acting valve in the cooling steam pipeline is opened, the opening time TON4 is accumulated until the total mass flow meter of the cooling steam pipeline reaches a value X. Then, the second quick-acting valve is quickly closed. The formula for calculating the value X is: ,in Defined as a proportional coefficient, determined by user debugging, P1 is the cumulative steam amount added by the first mass flow meter.

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