A hot water circulation control system and method for heating a pilot-scale device for active pharmaceutical ingredients.

Abstract

This invention relates to a hot water circulation control system and method for heating a pilot-scale apparatus for pharmaceutical raw materials, comprising: a hot water expansion tank, a hot water expansion tank breather pipe connected to a first port pipe of the hot water expansion tank, and hot water inlet and outlet pipes for the hot water expansion tube connected to a second port pipe of the hot water expansion tank; the temperature of the main hot water supply pipe can be controlled by a hot water heating heat exchanger, and this temperature can be adjusted according to the overall needs of the water users; the hot water temperature of the water users is precisely controlled by a water cooler, ensuring that the different hot water temperature requirements of different operating stages of the water users are met, and also ensuring that different water users have different hot water temperature requirements, thus improving the convenience of temperature control of the hot water circulation system; this invention improves the practicality of temperature control of the hot water circulation system in a pilot-scale apparatus for pharmaceutical raw materials and achieves good technical results.

Description

Technical Field

[0001] This invention relates to the field of active pharmaceutical ingredient (API) production technology, and in particular to a hot water circulation control system and method for heating a pilot-scale API production facility. Background Technology

[0002] In the production of active pharmaceutical ingredients (APIs), heating using hot water circulation systems is a common heating method, such as for heating reaction vessels, distillation vessels, and vacuum dryers. In pilot-scale plants, because different processes have different requirements for hot water temperature, and different operating stages of the same process also have different requirements for hot water temperature, it is essential to establish a hot water temperature control scheme that can flexibly adjust the hot water temperature.

[0003] The factors that need to be considered in the hot water heating circulation system of the pilot plant for active pharmaceutical ingredients are: first, for the convenience of pilot research, different processes have different requirements for hot water temperature; second, different operating stages of the same process have different requirements for hot water temperature; and third, the product is heat-sensitive and the temperature of the hot water needs to be strictly controlled.

[0004] Therefore, the present invention provides a hot water circulation control system and method for heating a pilot-scale device for raw materials. This method allows for flexible adjustment of the hot water temperature during the heating process, ensuring that different users have different requirements for hot water temperature, improving the convenience of temperature control in the hot water circulation system, facilitating pilot-scale research, and being easy and simple to operate. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing a hot water circulation control system and method for heating a pilot-scale device for active pharmaceutical ingredients.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A first aspect of the present invention is to provide a hot water circulation control system for heating a pilot-scale apparatus for a pharmaceutical raw material, comprising: a hot water expansion tank; a hot water expansion tank breathing pipe connected to a first port of the hot water expansion tank; a hot water expansion tube hot water inlet / outlet pipe connected to a second port of the hot water expansion tank; a hot water return main pipe with its output end connected to the hot water expansion tube hot water inlet / outlet pipe; a first hot water return pipe with its output end connected to the input end of the hot water return main pipe; a first reflux mechanism with its output end connected to the input end of the first hot water return pipe; a second hot water return pipe with its output end connected to the hot water return main pipe; a second reflux mechanism with its output end connected to the input end of the second hot water return pipe; a third hot water return pipe with its output end connected to the hot water return main pipe; and a third reflux mechanism with its output end connected to the input end of the third hot water return pipe; wherein,

[0008] The hot water expansion pipe is connected to the first hot water return pipe, the second hot water return pipe, and the third hot water return pipe, and the first hot water return pipe, the second hot water return pipe, and the third hot water return pipe are connected in parallel.

[0009] Further, the first return mechanism includes: a first water heater whose output end is connected to the input end of the first hot water return pipeline; a first hot water cooler whose output end is connected to the first input end pipeline; a first low-temperature water return pipeline and a first low-temperature water supply pipeline connected to the first hot water cooler pipeline; and a first hot water supply pipeline whose output end is connected to the input end of the first hot water cooler pipeline; wherein,

[0010] The first low-temperature water return pipeline and the first low-temperature water supply pipeline are connected in parallel.

[0011] Furthermore, the external pipeline of the first water heater is connected to a first temperature transmitter, and a first hot water regulating valve is provided between the first hot water supply pipeline and the first hot water cooler.

[0012] Further, the second return mechanism includes: a second water heater whose output end is connected to the input end of the second hot water return pipeline; a second hot water cooler whose output end is connected to the input end of the second hot water cooler; a second low-temperature water return pipeline and a second low-temperature water supply pipeline connected to the pipeline of the second hot water cooler; and a second hot water supply pipeline whose output end is connected to the input end of the second hot water cooler; wherein,

[0013] The second low-temperature water return pipeline and the second low-temperature water supply pipeline are connected in parallel.

[0014] Furthermore, the external pipeline of the second water heater is connected to a second temperature transmitter, and a second hot water regulating valve is installed between the second hot water supply pipeline and the second hot water cooler.

[0015] Further, the third return mechanism includes: a third water heater whose output end is connected to the input end of the third hot water return pipeline; a third hot water cooler whose output end is connected to the third input end pipeline; a third low-temperature water return pipeline and a third low-temperature water supply pipeline connected to the pipeline of the third hot water cooler; and a third hot water supply pipeline whose output end is connected to the input end of the third hot water cooler; wherein,

[0016] The third low-temperature water return pipeline and the third low-temperature water supply pipeline are connected in parallel.

[0017] Furthermore, the external pipeline of the third water heater is connected to a third temperature transmitter, and a third hot water regulating valve is installed between the third hot water supply pipeline and the third hot water cooler.

[0018] Furthermore, the input ends of the first hot water supply pipeline, the second hot water supply pipeline, and the third hot water supply pipeline are all connected to the output end pipeline of the main hot water supply pipe. A hot water temperature transmitter is connected to the middle pipeline of the main hot water supply pipe, and a hot water heating heat exchanger is connected to the input end pipeline of the main hot water supply pipe. A condensate return pipeline and a steam supply pipeline are connected in parallel outside the hot water heating heat exchanger, and a steam regulating valve is connected to the middle pipeline of the steam supply pipeline.

[0019] Furthermore, the input pipe of the hot water heating heat exchanger is connected to the downstream pipe of the hot water circulation pump, the input pipe of the downstream pipe of the hot water circulation pump is connected to the hot water circulation pump, and the input end of the hot water circulation pump is connected to the output pipe of the hot water return main pipe; the output pipe of the downstream pipe of the hot water circulation pump is connected to a hot water flow regulating inlet bypass, a hot water self-regulating differential pressure regulating valve is installed in the middle of the hot water flow regulating inlet bypass, the output pipe of the hot water flow regulating inlet bypass is connected to a hot water flow regulating outlet bypass, and the output end of the hot water flow regulating outlet bypass is connected to the input pipe of the hot water return main pipe.

[0020] A second aspect of the present invention is to provide a hot water circulation control method for heating a pilot-scale device for a pharmaceutical raw material, employing the aforementioned hot water circulation control system, and the specific steps are as follows:

[0021] S1. Hot water expansion: The hot water expansion tank is used to absorb the volume change caused by the expansion of hot water in the hot water circulation system. When hot water enters the hot water expansion tank from the hot water inlet and outlet pipes of the hot water expansion pipe, the gas in the hot water expansion tank is discharged from the hot water expansion tank breather pipe. When hot water is discharged from the hot water expansion tank from the hot water inlet and outlet pipes of the hot water expansion pipe, the air outside the hot water expansion tank enters the hot water expansion tank from the hot water expansion tank breather pipe.

[0022] S2, Hot water circulation: The hot water circulation pump is used to pressurize the hot water in the hot water return main pipe to the pipeline after the hot water circulation pump, and maintain a certain circulation pressure of hot water.

[0023] S3. Hot water flow regulation: When the number of usage points or the flow rate at each usage point in the hot water circulation system decreases, bypass regulation is performed through the hot water self-regulating differential pressure regulating valve; when the pressure difference across the hot water self-regulating differential pressure regulating valve increases, the number of hot water usage points or the flow rate at each usage point decreases, so the opening of the hot water self-regulating differential pressure regulating valve is increased, allowing more hot water to bypass the user points and return to the hot water return main pipe via the hot water flow regulation inlet bypass and the hot water flow regulation outlet bypass; when the pressure difference across the hot water self-regulating differential pressure regulating valve decreases, the number of hot water usage points or the flow rate at each usage point increases, so the opening of the hot water self-regulating differential pressure regulating valve is decreased, allowing more hot water to flow through the user points and then return to the hot water return main pipe.

[0024] S4. Hot water supply main pipe temperature regulation: A hot water temperature transmitter is installed on the hot water supply main pipe, and a steam regulating valve is installed on the steam supply line of the hot water heating heat exchanger; when the temperature of the hot water temperature transmitter is lower than the preset temperature value, the opening of the steam regulating valve is increased to increase the hot water temperature of the hot water supply main pipe; when the temperature of the hot water temperature transmitter is higher than the preset temperature value, the opening of the steam regulating valve is decreased to decrease the hot water temperature of the hot water supply main pipe.

[0025] S5. User point temperature control: A first hot water regulating valve is installed on the first hot water supply pipeline, and a first temperature transmitter is installed on the first water appliance; when the temperature value of the first temperature transmitter is lower than the preset temperature value, the opening of the first hot water regulating valve is increased to increase the temperature at the user point; when the temperature value of the first temperature transmitter is higher than the preset temperature value, the opening of the first hot water regulating valve is decreased to decrease the temperature at the user point.

[0026] S6. Precise Temperature Control at User Points: A first hot water cooler is installed on the first hot water supply line, and a first low-temperature water regulating valve is installed on the first low-temperature water supply line of the first hot water cooler. When reducing the opening of the first hot water regulating valve still cannot meet the first temperature regulation requirement, the first low-temperature water regulating valve is used for regulation. When the temperature value of the first temperature transmitter is lower than the preset temperature value, the opening of the first low-temperature water regulating valve is reduced to increase the temperature at the user point. When the temperature value of the first temperature transmitter is higher than the preset temperature value, the opening of the first low-temperature water regulating valve is increased to decrease the temperature at the user point.

[0027] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0028] The hot water circulation control method of the present invention can control the temperature of the main hot water supply pipe by setting a hot water heating heat exchanger, and the temperature can be adjusted according to the overall needs of the user point; by finely controlling the hot water temperature at the user point through the hot water cooler, the different hot water temperature requirements of the user point at different operating stages are guaranteed, as well as the different hot water temperature requirements of different user points, thus improving the convenience of temperature control of the hot water circulation system; the present invention improves the practicality of temperature control of the hot water circulation system of the raw material pilot plant and achieves good technical results. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the hot water circulation control system of the present invention;

[0030] The reference numerals in the figures include:

[0031] 1. Hot water expansion tank; 2. Hot water expansion tank breather pipe; 3. Hot water expansion pipe inlet / outlet pipe; 4. Hot water return main pipe; 5. Hot water circulation pump; 6. Hot water circulation pump downstream pipe; 7. Hot water flow regulating inlet bypass; 8. Hot water heating heat exchanger; 9. Condensate return pipe; 10. Steam supply pipe; 11. Steam regulating valve; 12. Hot water supply main pipe; 13. Hot water temperature transmitter; 141. First hot water supply pipe; 142. First hot water regulating valve; 143. First low-temperature water return pipe; 144. First hot water cooler; 145. First low-temperature water supply pipe; 146. First low-temperature water regulating valve; 147. First water appliance; 148. First hot water return pipe; 149. Second hot water heater; Water supply pipeline 151; second hot water regulating valve 152; second low-temperature water return pipeline 153; second hot water cooler 154; second low-temperature water supply pipeline 155; second low-temperature water regulating valve 156; second temperature transmitter 157; second water appliance 158; second hot water return pipeline 159; third hot water supply pipeline 161; third hot water regulating valve 162; third low-temperature water return pipeline 163; third hot water cooler 164; third low-temperature water supply pipeline 165; third low-temperature water regulating valve 166; third temperature transmitter 167; third water appliance 168; third hot water return pipeline 169; hot water flow regulating outlet bypass 17; hot water self-regulating differential pressure regulating valve 18. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0035] Example 1

[0036] Please see Figure 1This embodiment provides a hot water circulation control system for heating a pilot-scale device for a raw material drug, comprising: a hot water expansion tank 1; a hot water expansion tank breathing pipe 2 connected to a first port pipe of the hot water expansion tank 1; a hot water expansion pipe hot water inlet / outlet pipe 3 connected to a second port pipe of the hot water expansion tank 1; a hot water return main pipe 4 with its output end connected to the hot water inlet / outlet pipe 3; a first hot water return pipe 149 with its output end connected to the input end pipe of the hot water return main pipe 4; a first reflux mechanism with its output end connected to the input end pipe of the first hot water return pipe 149; a second hot water return pipe 159 with its output end connected to the hot water return main pipe 4; a second reflux mechanism with its output end connected to the input end pipe of the second hot water return pipe 159; a third hot water return pipe 169 with its output end connected to the hot water return main pipe 4; and a third reflux mechanism with its output end connected to the input end pipe of the third hot water return pipe 169.

[0037] The hot water expansion pipe 3 is connected to the first hot water return pipe 149, the second hot water return pipe 159 and the third hot water return pipe 169, and the first hot water return pipe 149, the second hot water return pipe 159 and the third hot water return pipe 169 are connected in parallel.

[0038] The first return mechanism includes: a first water heater 148 whose output end is connected to the input end of the first hot water return pipe 149; a first hot water cooler 144 whose output end is connected to the input end of the first water heater 148; a first low-temperature water return pipe 143 and a first low-temperature water supply pipe 145 connected to the first hot water cooler 144; and a first hot water supply pipe 141 whose output end is connected to the input end of the first hot water cooler 144; wherein, the first low-temperature water return pipe 143 and the first low-temperature water supply pipe 145 are connected in parallel; the external pipe of the first water heater 148 is connected to a first temperature transmitter 147, and the first hot water supply pipe 141 is connected to the first hot water cooler 149. A first hot water regulating valve is provided between 44; the second return mechanism includes: a second water heater 158 whose output end is connected to the input end of the second hot water return pipe 159, a second hot water cooler 154 whose output end is connected to the input end of the second water heater 158, a second low-temperature water return pipe 153 and a second low-temperature water supply pipe 155 connected to the second hot water cooler 154, and a second hot water supply pipe 151 whose output end is connected to the input end of the second hot water cooler 154; wherein, the second low-temperature water return pipe 153 and the second low-temperature water supply pipe 155 are connected in parallel; the third return mechanism includes: a third water heater 158 whose output end is connected to the input end of the third hot water return pipe 169. The system comprises a water heater 168, a third hot water cooler 164 whose output end is connected to the input end of the third water heater 168 via a pipeline, a third low-temperature water return pipeline 163 and a third low-temperature water supply pipeline 165 connected to the pipeline of the third hot water cooler 164 via a pipeline, and a third hot water supply pipeline 161 whose output end is connected to the input end of the third hot water cooler 164 via a pipeline; wherein, the third low-temperature water return pipeline 163 and the third low-temperature water supply pipeline 165 are connected in parallel; a third temperature transmitter 167 is connected to the external pipeline of the third water heater 168, and a third hot water regulating valve is provided between the third hot water supply pipeline 161 and the third hot water cooler 164; the first hot water supply pipeline 141 and the second hot water supply pipeline 164 are also included. The input ends of 51 and the third hot water supply pipeline 161 are both connected to the output end of the hot water supply main pipeline 12. A hot water temperature transmitter 13 is connected to the middle section of the hot water supply main pipeline 12. A hot water heating heat exchanger 8 is connected to the input end of the hot water supply main pipeline 12. A condensate return pipeline 9 and a steam supply pipeline 10 are connected in parallel outside the hot water heating heat exchanger 8. A steam regulating valve 11 is connected to the middle section of the steam supply pipeline 10. A hot water circulation pump downstream pipeline 6 is connected to the input end of the hot water circulation pump downstream pipeline 6. A hot water circulation pump 5 is connected to the input end of the hot water circulation pump 5 and is connected to the output end of the hot water return main pipeline 4.The output end of the hot water circulation pump downstream pipe 6 is connected to a hot water flow regulating inlet bypass 7. A self-regulating differential pressure regulating valve 18 is installed in the middle of the hot water flow regulating inlet bypass 7. The output end of the hot water flow regulating inlet bypass 7 is connected to a hot water flow regulating outlet bypass 17. The output end of the hot water flow regulating outlet bypass 17 is connected to the input end of the hot water return main pipe 4.

[0039] Example 2

[0040] This embodiment provides a hot water circulation control method for heating a pilot-scale device for active pharmaceutical ingredients (APIs), using the hot water circulation control system of Embodiment 1. The specific steps are as follows:

[0041] S1. Hot water expansion: Hot water expansion tank 1 is used to absorb the volume change caused by the expansion of hot water in the hot water circulation system; when hot water enters hot water expansion tank 1 from hot water expansion pipe inlet / outlet pipe 3, the gas in hot water expansion tank 1 is discharged from hot water expansion tank breather pipe 2; when hot water is discharged from hot water expansion pipe inlet / outlet pipe 3, the air outside hot water expansion tank 1 enters hot water expansion tank 1 from hot water expansion tank breather pipe 2.

[0042] S2, Hot water circulation: Hot water circulation pump 5 is used to pressurize the hot water in the hot water return main pipe 4 to the hot water circulation pump downstream pipe 6, and maintain a certain circulation pressure of hot water;

[0043] S3. Hot water flow regulation: When the number of usage points or the flow rate at the usage points in the hot water circulation system decreases, bypass regulation is performed through the hot water self-regulating differential pressure regulating valve 18; when the pressure difference across the hot water self-regulating differential pressure regulating valve 18 increases, the number of hot water usage points or the flow rate at the usage points decreases, so the opening of the hot water self-regulating differential pressure regulating valve 18 is increased, allowing more hot water to bypass the user points and return to the hot water return main pipe 4 via the hot water flow regulation inlet bypass 7 and the hot water flow regulation outlet bypass 17; when the pressure difference across the hot water self-regulating differential pressure regulating valve 18 decreases, the number of hot water usage points or the flow rate at the usage points increases, so the opening of the hot water self-regulating differential pressure regulating valve 18 is decreased, allowing more hot water to flow through the user points and then return to the hot water return main pipe 4.

[0044] S4. Hot water supply main pipe temperature regulation: A hot water temperature transmitter 13 is installed on the hot water supply main pipe 12, and a steam regulating valve 11 is installed on the steam supply pipe 10 of the hot water heating heat exchanger 8; when the temperature of the hot water temperature transmitter 13 is lower than the preset temperature value, the opening of the steam regulating valve 11 is increased to increase the hot water temperature of the hot water supply main pipe 12; when the temperature of the hot water temperature transmitter 13 is higher than the preset temperature value, the opening of the steam regulating valve 11 is decreased to decrease the hot water temperature of the hot water supply main pipe 12.

[0045] S5. User Point Temperature Control: A first hot water regulating valve 142 is installed on the first hot water supply pipeline 141, and a first temperature transmitter 147 is installed on the first water heater 148; when the temperature value of the first temperature transmitter 147 is lower than the preset temperature value, the opening of the first hot water regulating valve 142 is increased to raise the temperature at the user point; when the temperature value of the first temperature transmitter 147 is higher than the preset temperature value, the opening of the first hot water regulating valve 142 is decreased to lower the temperature at the user point.

[0046] S6. Precise Temperature Control at User Points: A first hot water cooler 144 is installed on the first hot water supply pipeline 141, and a first low-temperature water regulating valve 146 is installed on the first low-temperature water supply pipeline 145 of the first hot water cooler 144. When reducing the opening of the first hot water regulating valve 142 still cannot meet the temperature regulation requirements of the first water heater 148, the first low-temperature water regulating valve 146 is used for regulation. When the temperature value of the first temperature transmitter 147 is lower than the preset temperature value, the opening of the first low-temperature water regulating valve 146 is reduced to increase the temperature at the user point. When the temperature value of the first temperature transmitter 147 is higher than the preset temperature value, the opening of the first low-temperature water regulating valve 146 is increased to decrease the temperature at the user point.

[0047] During the research of a pilot plant for a pharmaceutical raw material, different hot water heating temperatures needed to be set for the reaction vessel, distillation vessel, and drying oven. Using the aforementioned hot water circulation control method, the following data was obtained:

[0048] Operation time: intermittent

[0049] Workshop staffing: 1 operator.

[0050] During operation, temperature control is convenient, and the temperature of the reaction vessel, distillation vessel, and drying oven can be well maintained to complete product production research.

[0051] Example 3

[0052] Under the conditions described in Example 2, when a pilot plant of a pharmaceutical raw material factory was researching products, the reaction vessel and distillation vessel needed to be operated for a certain period of time. This required precise temperature control to reduce the hot water supply temperature and prevent overheating of the equipment, which could affect product quality. Using the hot water circulation control method of this invention, the following data were obtained:

[0053] Operation time: intermittent

[0054] Workshop staffing: 1 operator.

[0055] During operation, temperature control is convenient, and the temperature of the reaction vessel can be well adjusted; the temperature of the distillation vessel in the later stage ensures the quality of the product and completes the product production research.

[0056] Compare with Example 1

[0057] During product research at a pilot plant of a pharmaceutical raw material factory, different hot water heating temperatures needed to be set for the reaction vessel, distillation vessel, and drying oven. Using a traditional hot water circulation control method, the following data was obtained:

[0058] Operation time: intermittent

[0059] During operation, three hot water circulation systems need to be set up to meet the corresponding temperature control requirements.

[0060] Compare with Example 2

[0061] During product research at a pilot plant of a certain active pharmaceutical ingredient (API) facility, the hot water temperature in the reaction vessel and distillation vessel became too high after a certain period of operation. It was necessary to reduce the hot water temperature to varying degrees and implement precise temperature control to prevent overheating within the equipment and affecting product quality. Using a traditional hot water circulation control method, the following data was obtained:

[0062] Operation time: intermittent

[0063] During operation, because no hot water cooling measures were implemented, even reducing the hot water flow rate could not meet the temperature control requirements. The hot water had to be turned on and off intermittently, resulting in unstable temperatures and affecting the quality of the final product.

[0064] In summary, the hot water circulation control method of the present invention, by setting up a hot water heating heat exchanger 8, can control the temperature of the hot water supply main pipe, which can be adjusted according to the overall needs of the user point; by finely controlling the hot water temperature at the user point through the hot water cooler, it ensures that the different hot water temperature requirements of the user point at different operating stages are met, and also ensures that different user points have different hot water temperature requirements, thus improving the convenience of temperature control of the hot water circulation system; the present invention improves the practicality of temperature control of the hot water circulation system of the raw material pilot plant and achieves good technical results.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A hot water circulation control system for heating a pilot-scale device for raw pharmaceutical materials, characterized in that, include: A hot water expansion tank (1), a hot water expansion tank breathing pipe (2) connected to the first port pipe of the hot water expansion tank (1), a hot water expansion pipe hot water inlet / outlet pipe (3) connected to the second port pipe of the hot water expansion tank (1), a hot water return main pipe (4) with its output end connected to the hot water inlet / outlet pipe (3), a first hot water return pipe (149) with its output end connected to the input end pipe of the hot water return main pipe (4), a first reflux mechanism with its output end connected to the input end pipe of the first hot water return pipe (149), a second hot water return pipe (159) with its output end connected to the hot water return main pipe (4), a second reflux mechanism with its output end connected to the input end pipe of the second hot water return pipe (159), a third hot water return pipe (169) with its output end connected to the hot water return main pipe (4), and a third reflux mechanism with its output end connected to the input end pipe of the third hot water return pipe (169); wherein, The hot water expansion pipe hot water inlet and outlet pipe (3) is connected to the first hot water return pipe (149), the second hot water return pipe (159) and the third hot water return pipe (169), and the first hot water return pipe (149), the second hot water return pipe (159) and the third hot water return pipe (169) are connected in parallel; The first return mechanism includes: a first water heater (148) whose output end is connected to the input end of the first hot water return pipe (149); a first hot water cooler (144) whose output end is connected to the input end of the first water heater (148); a first low-temperature water return pipe (143) and a first low-temperature water supply pipe (145) connected to the pipe of the first hot water cooler (144); and a first hot water supply pipe (141) whose output end is connected to the input end of the first hot water cooler (144); wherein, The first low-temperature water return pipeline (143) and the first low-temperature water supply pipeline (145) are connected in parallel; The second return mechanism includes: a second water heater (158) whose output end is connected to the input end of the second hot water return pipeline (159); a second hot water cooler (154) whose output end is connected to the input end of the second water heater (158); a second low-temperature water return pipeline (153) and a second low-temperature water supply pipeline (155) connected to the pipeline of the second hot water cooler (154); and a second hot water supply pipeline (151) whose output end is connected to the input end of the second hot water cooler (154); wherein, The second low-temperature water return pipeline (153) and the second low-temperature water supply pipeline (155) are connected in parallel; The third return mechanism includes: a third water heater (168) whose output end is connected to the input end of the third hot water return pipeline (169); a third hot water cooler (164) whose output end is connected to the input end of the third water heater (168); a third low-temperature water return pipeline (163) and a third low-temperature water supply pipeline (165) connected to the pipeline of the third hot water cooler (164); and a third hot water supply pipeline (161) whose output end is connected to the input end of the third hot water cooler (164). The third low-temperature water return pipeline (163) and the third low-temperature water supply pipeline (165) are connected in parallel; The input ends of the first hot water supply pipeline (141), the second hot water supply pipeline (151) and the third hot water supply pipeline (161) are all connected to the output end pipeline of the hot water supply main pipe (12). A hot water temperature transmitter (13) is connected to the middle pipeline of the hot water supply main pipe (12). A hot water heating heat exchanger (8) is connected to the input end pipeline of the hot water supply main pipe (12). A condensate return pipeline (9) and a steam supply pipeline (10) are connected in parallel outside the hot water heating heat exchanger (8). A steam regulating valve (11) is connected to the middle pipeline of the steam supply pipeline (10).

2. The hot water circulation control system according to claim 1, characterized in that, The external pipeline of the first water heater (148) is connected to a first temperature transmitter (147), and a first hot water regulating valve is provided between the first hot water supply pipeline (141) and the first hot water cooler (144).

3. The hot water circulation control system of claim 1, wherein, The external pipeline of the second water heater (158) is connected to a second temperature transmitter (157), and a second hot water regulating valve is provided between the second hot water supply pipeline (151) and the second hot water cooler (154).

4. The hot water circulation control system of claim 1, wherein The external pipeline of the third water heater (168) is connected to a third temperature transmitter (167), and a third hot water regulating valve is provided between the third hot water supply pipeline (161) and the third hot water cooler (164).

5. The hot water circulation control system of claim 1, wherein, The input pipe of the hot water heating heat exchanger (8) is connected to the hot water circulation pump downstream pipe (6), the input pipe of the hot water circulation pump downstream pipe (6) is connected to the hot water circulation pump (5), the input end of the hot water circulation pump (5) is connected to the output end pipe of the hot water return main pipe (4); the output end pipe of the hot water circulation pump downstream pipe (6) is connected to the hot water flow regulating inlet bypass (7), the hot water flow regulating inlet bypass (7) is provided with a hot water self-regulating differential pressure regulating valve (18) in the middle, the output end pipe of the hot water flow regulating inlet bypass (7) is connected to the hot water flow regulating outlet bypass (17), and the output end of the hot water flow regulating outlet bypass (17) is connected to the input end pipe of the hot water return main pipe (4).

6. A method for controlling hot water circulation in a pilot-scale device for heating a pharmaceutical raw material, employing the hot water circulation control system as described in any one of claims 1-5, comprising the following steps: S1. Hot water expansion: The hot water expansion tank (1) is used to absorb the volume change caused by the expansion of hot water in the hot water circulation system; when hot water enters the hot water expansion tank (1) from the hot water inlet / outlet pipe (3), the gas in the hot water expansion tank (1) is discharged from the hot water expansion tank breather pipe (2); when hot water is discharged from the hot water expansion tank (1) from the hot water inlet / outlet pipe (3), the air outside the hot water expansion tank (1) enters the hot water expansion tank (1) from the hot water expansion tank breather pipe (2). S2, Hot water circulation: The hot water circulation pump (5) is used to pressurize the hot water in the hot water return main pipe (4) to the hot water circulation pump downstream pipe (6) to maintain a certain circulation pressure of hot water; S3. Hot water flow regulation: When the number of usage points or the flow rate at the usage points in the hot water circulation system decreases, bypass regulation is performed through the hot water self-regulating differential pressure regulating valve (18); when the pressure difference across the hot water self-regulating differential pressure regulating valve (18) increases, the number of hot water usage points or the flow rate at the usage points decreases, so the opening of the hot water self-regulating differential pressure regulating valve (18) is increased, so that more hot water does not pass through the water heater, but returns to the hot water return main pipe (4) through the hot water flow regulation inlet bypass (7) and the hot water flow regulation outlet bypass (17); when the pressure difference across the hot water self-regulating differential pressure regulating valve (18) decreases, the number of hot water usage points or the flow rate at the usage points increases, so the opening of the hot water self-regulating differential pressure regulating valve (18) is decreased, so that more hot water flows through the water heater and then returns to the hot water return main pipe (4). S4. Hot water supply main pipe temperature regulation: A hot water temperature transmitter (13) is installed on the hot water supply main pipe (12), and a steam regulating valve (11) is installed on the steam supply pipeline (10) of the hot water heating heat exchanger (8); when the temperature of the hot water temperature transmitter (13) is lower than the preset temperature value, the opening of the steam regulating valve (11) is increased to raise the hot water temperature of the hot water supply main pipe (12); when the temperature of the hot water temperature transmitter (13) is higher than the preset temperature value, the opening of the steam regulating valve (11) is decreased to lower the hot water temperature of the hot water supply main pipe (12). S5. Water appliance temperature control: A first hot water regulating valve (142) is provided on the first hot water supply pipeline (141), and a first temperature transmitter (147) is provided on the first water appliance (148); when the temperature value of the first temperature transmitter (147) is lower than the preset temperature value, the opening of the first hot water regulating valve (142) is increased to increase the temperature of the water appliance; when the temperature value of the first temperature transmitter (147) is higher than the preset temperature value, the opening of the first hot water regulating valve (142) is decreased to decrease the temperature of the water appliance. S6. Precise control of water heater temperature: A first hot water cooler (144) is provided on the first hot water supply pipeline (141), and a first low temperature water regulating valve (146) is provided on the first low temperature water supply pipeline (145) of the first hot water cooler (144). When the temperature regulation requirement of the first water heater (148) cannot be met by reducing the opening of the first hot water regulating valve (142), the first low temperature water regulating valve (146) is used for regulation. When the temperature value of the first temperature transmitter (147) is lower than the preset temperature value, the opening of the first low temperature water regulating valve (146) is reduced to increase the temperature of the water heater. When the temperature value of the first temperature transmitter (147) is higher than the preset temperature value, the opening of the first low temperature water regulating valve (146) is increased to decrease the temperature of the water heater.

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