Sterilization kettle direct-heating and indirect-cooling sterilization process and sterilization kettle

Abstract

The invention relates to the technical field of sterilization kettles, and provides a sterilization kettle direct-heating and indirect-cooling sterilization process and a sterilization kettle.The sterilization kettle direct-heating and indirect-cooling sterilization process comprises the following steps that S1, process water is injected into a sterilization kettle through a water injection pump; s2, the exhaust valve is kept open, and the water injection pump and the water injection valve are closed; s3, steam is injected into the process water through a steam preheating valve to preheat the process water, so that the temperature of the process water is close to that of the to-be-sterilized product; s4, the process water enters a circulating pump through a hot water circulating valve to be circularly sprayed, steam is supplied into the sterilization kettle through a steam valve to heat the process water, air is supplied through an air supply valve, air is exhausted through an exhaust valve, and therefore the pressure in the sterilization kettle is adjusted; s5, after the process water is heated to a preset temperature, carrying out heat preservation until sterilization is finished; steam is directly injected into the process water for heating through the steam preheating valve and the corresponding pipeline, so that direct heating of the process water can be realized, energy loss can be remarkably reduced, and the steam preheating device is flexible and convenient to apply.

Description

Technical Field

[0001] This invention relates to the field of sterilization equipment technology, and in particular to a direct heating and intermittent cooling sterilization process and a sterilization equipment. Background Technology

[0002] An autoclave is a widely used sterilization device, primarily used in the food industry. After food packaging is completed, the outer packaging is sterilized in an autoclave to ensure food safety. Autoclaves are mainly divided into horizontal and vertical types based on their structure. These differences in structure result in completely different sterilization processes.

[0003] An existing invention patent with authorization announcement number CN102742914B discloses a vertical sterilization autoclave, including an autoclave body, a feeding port at the top of the autoclave body with an upper cover device installed on the feeding port, a discharge port at the bottom of the autoclave body with a lower cover device installed on the discharge port, a cold water circulation system, a hot water circulation system and a steam inlet pipeline connected to the autoclave body, and a condensate recovery device also provided on the autoclave body; Another utility model patent with authorization announcement number CN216292900U discloses a sterilization kettle, including a kettle body, a heat exchanger, a steam generating device and a cooling water tower. A steam proportional valve is provided between the steam generating device and the heat exchanger, and a cooling valve group is provided between the cooling water tower and the heat exchanger. During the heating and / or sterilization stages, the steam proportional valve is opened and the amount of steam delivered to the other side of the heat exchanger is determined based on the temperature of the sterilization process water in the kettle body. As in the above technical solutions, one uses a hot water tank to store the sterilization hot water, and the other uses a heat exchanger to heat the process water. Both are indirect supply or heating of the process water, which has the following problems: ① In the process of sending hot water from the hot water tank into the sterilization vessel, or using a heat exchanger to heat the process water before transporting it, heat loss is inevitable, resulting in high power consumption and wasted resources; ② After the sterilized products are packaged, their temperatures vary and there is a temperature difference between the sterilized products and the process water inside the sterilization vessel. Therefore, the temperature of the process water inside the sterilization vessel needs to be gradually adjusted according to the sterilization stage. It is necessary to avoid excessive cooling that would cause the food to cool down, and to avoid excessive heating that would affect the nutrition and taste of the food products due to sudden temperature changes. If hot water tanks are used, multiple tanks need to be installed to achieve a stable supply of hot water at different temperatures. If heat exchangers are used, several supporting devices are required, which is not only costly but also inflexible in application. Therefore, there is an urgent need to improve the existing technology. Summary of the Invention

[0004] In view of this, the present invention proposes a direct heating and indirect cooling sterilization process and sterilizer that saves energy and provides flexible and convenient temperature control, thereby solving the problems of high energy consumption, insufficient temperature control and inconvenient application of existing sterilization processes.

[0005] The technical solution of this invention is implemented as follows: On one hand, the present invention provides a direct heating and indirect cooling sterilization process for a sterilizing autoclave, comprising the following steps: S1. Open the exhaust valve and the water injection valve, and use the water injection pump to inject process water into the sterilization vessel. S2. Keep the vent valve open and close the water pump and water valve; S3. Open the steam preheating valve, open the steam silencer, close the exhaust valve, and inject steam into the process water through the steam preheating valve to preheat the process water so that the temperature of the process water is close to that of the product to be sterilized. S4. Close the steam preheating valve and steam silencer, and open the circulating pump, hot water circulating valve, steam valve, air supply valve and exhaust valve. The process water enters the circulating pump through the hot water circulating valve for circulating spraying. Steam is supplied to the sterilizer through the steam valve to heat the process water. At the same time, air is supplied through the air supply valve and exhaust is discharged through the exhaust valve, thereby regulating the pressure inside the sterilizer. S5. After the process water is heated to the preset temperature, it is kept at that temperature until sterilization is complete. S6. Perform a slight cooling on the sterilizer so that the internal temperature of the sterilizer reaches the set slight cooling temperature. S7. Cool the sterilizer until the internal temperature of the sterilizer reaches the set cooling temperature.

[0006] Based on the above technical solutions, preferably, a water level is set in the sterilization tank, the water level is lower than the product to be sterilized and submerges the pipeline connected to the steam preheating valve, and the process water is injected to the water level and then stopped.

[0007] Based on the above technical solutions, preferably, in steps S4, S5, S6 and S7, gas is supplied to the sterilizer through the gas replenishment valve to pressurize it, and the pressure is regulated by the exhaust valve. PID control is implemented on the gas replenishment valve, exhaust valve and steam valve, and the valve opening is adjusted in real time with reference to the linear temperature value of the sterilizer, so that the temperature change curve of the sterilizer is a smooth curve.

[0008] Based on the above technical solutions, preferably, step S6 includes: S61. A heat exchanger is installed on the sterilization autoclave, and a cooling circulation valve and a return water pipe are installed on the heat exchanger. S62. Close the hot water circulation valve, and use the circulation pump to send the process water through the cooling circulation valve into the heat exchanger for heat dissipation and slight cooling. Then, return the slightly cooled process water to the sterilization tank through the return water pipe.

[0009] Based on the above technical solution, preferably, step S8 is also included, which includes: S81. Turn off the circulation pump; S82. Keep the air supply valve and the exhaust valve open, supply gas into the sterilizer through the air supply valve to pressurize it, and regulate the drainage pressure by venting through the exhaust valve. S83. Open the drain valve to drain the excess process water in the sterilization tank. After the process water level is lower than the initial level, close the drain valve.

[0010] Based on the above technical solution, preferably, step S9 is also included, which includes: S91. Keep the exhaust valve open and close the air supply valve; S92. Use the exhaust valve to release excess pressure, reducing the internal pressure of the sterilizer to the door opening pressure; S93. Open the drain valve to discharge excess cooling water, so that the process water level is lower than the initial level.

[0011] Based on the above technical solutions, preferably, step S4 is executed at least five times and step S7 is executed at least three times to regulate the internal temperature and pressure of the sterilizer in stages.

[0012] On the other hand, the present invention provides a sterilization autoclave, employing the above-mentioned direct heating and indirect cooling sterilization process, comprising: a sterilization autoclave, a steam preheating valve, a water injection valve, a water injection pump, a steam valve, a steam silencing mechanism, a circulating pump, a hot water circulating valve, an exhaust valve, and a gas replenishment valve, wherein... The sterilization autoclave is a horizontal sterilization autoclave; The steam preheating valve, water injection valve, steam valve, hot water circulation valve, exhaust valve, and air replenishment valve are all connected to the sterilization autoclave. The outlet of the water pump is connected to the water injection valve; The steam silencing mechanism is connected to the steam preheating valve; The inlet of the circulating pump is connected to the sterilization vessel, and the outlet of the circulating pump is connected to the hot water circulation valve.

[0013] Based on the above technical solutions, the preferred embodiment also includes a heat exchanger, a cooling circulation valve, a return water pipe, and a drain valve, wherein... The heat exchanger is located on the outside of the sterilization autoclave; One end of the cooling circulation valve is connected to the outlet of the circulation pump, and the other end is connected to one of the inlets of the heat exchanger. One end of the return water pipe is connected to one outlet of the heat exchanger, and the other end is connected to the sterilization tank; The drain valve is connected to the sterilization autoclave.

[0014] Based on the above technical solutions, preferably, the pipe opening connecting the steam preheating valve and the sterilization autoclave is provided with a first steam pipeline, and the first steam pipeline is located on the lower side of the product tray. The port connecting the steam valve to the sterilizer is equipped with a second steam line, which is located between the product tray and the first steam line.

[0015] The direct-heating and intermittent-cooling sterilization process and sterilizer of the present invention have the following advantages over the prior art: This sterilization process directly injects steam into the process water through a steam preheating valve and corresponding pipelines for heating. This allows for direct heating of the process water, which significantly reduces energy loss and facilitates temperature control based on the product to be sterilized. It is flexible, convenient, and low-cost in application. In the preheating stage of this sterilization process, when steam is introduced through the steam preheating valve, the overall temperature inside the sterilization vessel can be adjusted when steam emerges from the process water to ensure the consistency of the temperature inside the sterilization vessel. This helps to ensure stable and reliable operation and also makes the temperature of all products to be sterilized more uniform, so as to avoid excessive temperature differences affecting product quality. During this sterilization process, air is continuously supplied through the air supply valve and vented through the air exhaust valve, thus achieving precise control of the pressure inside the sterilizer. At the same time, the air supply valve, air exhaust valve, and steam valve are subject to PID control, and the valve openings are adjusted in real time with reference to the linear temperature value of the sterilizer, so that the temperature change curve inside the sterilizer is a smooth curve, which helps to ensure the stability of operation and ensure reliable use. During the drainage process, the exhaust pressure and drainage pressure are regulated by the air supply valve and the exhaust valve, and the process water level is kept below the initial level. This ensures the structural stability of the sterilization vessel, avoids the impact of pressure changes on the internal products after the temperature drops, and also helps to control the process water level during subsequent sterilization processes. In this sterilization vessel structure, the steam preheating valve directly injects steam into the process water through the first steam pipeline for heating, which can ensure the heating rate and facilitate rapid application; the steam valve supplies steam into the sterilization vessel through the second steam pipeline, which can rapidly raise the temperature of the sprayed process water, thereby ensuring that the process water reaches the required sterilization temperature, and also helps to maintain the humidity inside the sterilization vessel, thus ensuring the sterilization quality. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a process flow diagram of the direct heating and intermittent cooling sterilization process of the sterilization autoclave of the present invention; Figure 2 This is a perspective view of the sterilization vessel of the present invention; Figure 3 This is a second perspective perspective view of the sterilization vessel of the present invention; Figure 4 This is a cross-sectional view of the sterilization vessel of the present invention; In the diagram: 1. Sterilization autoclave; 2. Steam preheating valve; 3. Water injection valve; 4. Water injection pump; 5. Steam valve; 6. Steam silencing mechanism; 7. Circulation pump; 8. Hot water circulation valve; 9. Exhaust valve; 10. Air replenishment valve; 11. Heat exchanger; 12. Cooling circulation valve; 13. Return water pipe; 14. Drain valve; 201. First steam pipeline; 501. Second steam pipeline; 100. Product tray. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, the direct heating and indirect cooling sterilization process of the sterilizer of the present invention includes the following steps: S1, opening the exhaust valve 9 and the water injection valve 3, and injecting process water into the sterilizer 1 by the water injection pump 4; S2, keeping the exhaust valve 9 open, and closing the water injection pump 4 and the water injection valve 3; S3, opening the steam preheating valve 2 and the steam silencing mechanism 6, closing the exhaust valve 9, and injecting steam into the process water through the steam preheating valve 2 to preheat the process water so that the temperature of the process water is close to that of the product to be sterilized; S4, closing the steam preheating valve 2 and the steam silencing mechanism 6, and opening the circulation pump 7 to circulate hot water. The process water is circulated and sprayed through the hot water circulation valve 8 into the circulation pump 7. Steam is supplied into the sterilizer 1 through the steam valve 5 to heat the process water. At the same time, air is supplied through the air supply valve 10 and air is discharged through the exhaust valve 9, thereby regulating the pressure inside the sterilizer 1. S5: After the process water is heated to the preset temperature, it is kept at the temperature until sterilization is completed. S6: The sterilizer 1 is slightly cooled down so that the internal temperature of the sterilizer 1 reaches the slightly cooled set temperature. S7: The sterilizer 1 is cooled down so that the internal temperature of the sterilizer 1 reaches the cooled set temperature.

[0020] As described above, during the sterilization process, the water injection pump 4 delivers process water to the water injection valve 3. The process water enters the sterilization vessel through the water injection valve 3 and reaches the set liquid level. Specifically, a water level is set in sterilizer 1. The water level is lower than the product to be sterilized and does not exceed the pipeline connected to steam preheating valve 2. Process water is injected until the water level is reached and then stopped. Thus, when the steam preheating valve 2 introduces steam into the sterilizer 1, the steam is directly supplied into the interior of the process water, thereby achieving rapid preheating of the process water. At the same time, after the steam emerges from the process water, it can also regulate the temperature of the products, so that the temperature of several products to be sterilized tends to be consistent, which is conducive to ensuring the consistency of the products after sterilization. Specifically, the steam supply of steam preheating valve 2 can be controlled to heat only the process water without heating the product to be sterilized. This can be achieved by controlling the amount of steam supplied. Once the temperature of the process water and the product to be sterilized are consistent, subsequent operations can be performed. Among them, the steam preheating valve 2 is connected to a pipeline submerged in process water, and a steam silencing mechanism 6 is installed on the pipeline to achieve silencing when steam is supplied, which helps to eliminate noise and reduce the vibration of the sterilization vessel. After the process water in the sterilizer is heated, the steam preheating valve 2 is closed. At this time, steam is supplied to the sterilizer 1 through the steam valve 5, and the circulation pump 7 is turned on. The process water enters the circulation pump 7 through the hot water circulation valve 8. The circulation pump 7 will circulate and spray the process water in the sterilizer 1. During this process, the sprayed process water comes into contact with the steam and will be further heated to reach the predetermined sterilization temperature. At this time, the inside of the sterilizer 1 is kept warm. After the sterilization time is reached, the sterilizer 1 is slightly cooled down. This can avoid the problem of uncontrollable pressure caused by excessive temperature difference between the high temperature air and water vapor inside.

[0021] This sterilization process injects steam into the process water through a steam preheating valve and corresponding pipelines for heating, which can directly heat the process water. This can significantly reduce energy loss and facilitate the adjustment of heating temperature according to the product to be sterilized, making it flexible and convenient to use. In the preheating stage of this sterilization process, when steam is introduced through the steam preheating valve, the overall temperature inside the sterilization vessel can be adjusted when steam emerges from the process water. This ensures the stable and consistent temperature of the sterilization vessel, which is beneficial for ensuring stable and reliable operation. It also makes the temperature of all products to be sterilized more uniform, so as to avoid excessive temperature differences that may affect product quality. In steps S4, S5, S6 and S7, gas is supplied into the sterilizer 1 through the gas supply valve 10 to pressurize it, and the pressure is regulated by the exhaust valve 9. PID control is implemented on the gas supply valve 10, the exhaust valve 9 and the steam valve 5, and the valve opening of the gas supply valve 10, the exhaust valve 9 and the steam valve 5 are adjusted in real time with reference to the linear temperature value of the sterilizer 1, so that the temperature change curve of the sterilizer 1 is a smooth curve. As mentioned above, during this sterilization process, air is continuously supplied through the air supply valve 10 and vented in real time through the exhaust valve 9, which makes it easy to control the internal pressure of the sterilization vessel. Meanwhile, the air supply valve 10, exhaust valve 9, and steam valve 5 are subject to PID control, and the valve openings of the air supply valve 10, exhaust valve 9, and steam valve 5 are adjusted in real time with reference to the linear temperature value of the sterilizer, so that the temperature change curve inside the sterilizer 1 is a smooth curve, which helps to ensure the stability of operation and ensure reliable use.

[0022] Step S6 includes: S61, installing a heat exchanger 11 on the sterilizer 1, and installing a cooling circulation valve 12 and a return water pipe 13 on the heat exchanger 11; S62, closing the hot water circulation valve 8, and using the circulation pump 7 to send the process water through the cooling circulation valve 12 into the heat exchanger 11 for heat dissipation and slight cooling, and then returning the slightly cooled process water to the sterilizer 1 through the return water pipe 13; As described above, in this sterilization process, the temperature is reduced by heat exchanger 11 during the micro-cooling stage. After the heat preservation is completed, the circulation pump 7 is turned on, which sends the process water into the heat exchanger 11 through the cooling circulation valve 12. The process water is cooled by the heat exchanger 11, and then the process water is returned to the sterilization tank 1 through the outlet of the heat exchanger 11. Among them, heat exchanger 11 can be a gas-liquid heat exchanger or a liquid-liquid heat exchanger.

[0023] Step S8 includes: S81, turning off the circulating pump 7; S82, keeping the air supply valve 10 and the exhaust valve 9 open, supplying gas into the sterilizer 1 through the air supply valve 10 to pressurize it, and venting and regulating the pressure through the exhaust valve 9 to control the drainage pressure; S83, opening the drain valve 14 to drain the excess process water in the sterilizer 1, and closing the drain valve 14 after the process water level is lower than the initial level. As mentioned above, during the drainage stage of this sterilization process, the air supply valve 10 and the exhaust valve 9 remain open. The air supply valve 10 supplies air, while the exhaust valve 9 exhausts air, and the process water is discharged simultaneously through the drain valve 14. This effectively avoids rapid changes in internal pressure of the sterilizer, which helps ensure the reliability and safety of the sterilizer's operation. In particular, when draining water, the process water level is controlled to be lower than the initial liquid level, so that the sterilizer 1 has space to accommodate the process water left after cooling.

[0024] During the drainage process, the exhaust pressure and drainage pressure are regulated by the air supply valve 10 and the exhaust valve 9, and the process water level is kept below the initial level. This ensures the structural stability of the sterilization vessel, avoids the internal products from being affected by pressure changes after the temperature drops, and also helps to control the process water level during subsequent sterilization processes. Step S9 includes: S91, keeping the exhaust valve 9 open and closing the air supply valve 10; S92, using the exhaust valve 9 to release excess pressure, reducing the internal pressure of the sterilizer 1 to the opening pressure; S93, opening the drain valve 14 to discharge excess cooling water, reducing the process water level to below the initial level. As described above, this sterilization process involves secondary drainage. Before drainage, excess pressure is first released through exhaust valve 9 to reduce the internal pressure of sterilizer 1 to the door opening pressure. Then, excess cooling water is released to reduce the process water level to below the initial level, at which point the door can be opened and the sterilized product can be removed. This step prepares for the next sterilization process, leaving ample space to prevent water vapor from entering and affecting the process water volume and level.

[0025] Step S4 is executed at least five times, and step S7 is executed at least three times, to regulate the internal temperature and pressure of the sterilizer 1 in stages; in this way, the heating and temperature rise can be carried out in stages, thereby ensuring the stability of the sterilization process.

[0026] like Figures 2-4 As shown, the sterilization vessel of the present invention uses the above-mentioned direct heating and indirect cooling sterilization process and includes: sterilization vessel 1, steam preheating valve 2, water injection valve 3, water injection pump 4, steam valve 5, steam silencing mechanism 6, circulation pump 7, hot water circulation valve 8, exhaust valve 9, air replenishment valve 10, heat exchanger 11, cooling circulation valve 12, return water pipe 13, and drain valve 14.

[0027] like Figures 2-4 As shown, sterilization vessel 1 is a horizontal sterilization vessel; steam preheating valve 2, water injection valve 3, steam valve 5, hot water circulation valve 8, exhaust valve 9 and air replenishment valve 10 are all connected to sterilization vessel 1; the outlet of water injection pump 4 is connected to water injection valve 3; steam silencing mechanism 6 is connected to steam preheating valve 2; the inlet of circulation pump 7 is connected to sterilization vessel 1, and the outlet of circulation pump 7 is connected to hot water circulation valve 8. As described above, the sterilization tank 1 is a horizontal sterilization tank with a tank door at one end. After the tank door is opened, the product tray 100 and the products it carries can be sent into the sterilization tank by a trolley. Specifically, guide rails are provided on the inner wall of the sterilization tank for the trolley to move. After the product is placed on the product tray 100 and placed into the sterilizer 1, the water pump 4 injects a certain amount of process water into the sterilizer 1. Then, steam is injected into the process water through the steam preheating valve 2 to heat it up until the temperature of the process water is consistent with that of the product. Then, the circulation pump 7 circulates the heated process water. The process water is lifted from the bottom to the top of the sterilizer and sprayed down. At the same time, the steam valve 5 is opened to heat the sprayed process water, thereby maintaining the sterilization temperature. After sterilization, wait for it to cool down before removing the product.

[0028] like Figure 3As shown, the heat exchanger 11 is located outside the sterilization vessel 1; one end of the cooling circulation valve 12 is connected to the outlet of the circulation pump 7, and the other end is connected to one inlet of the heat exchanger 11; one end of the return water pipe 13 is connected to one outlet of the heat exchanger 11, and the other end is connected to the sterilization vessel 1; the drain valve 14 is connected to the sterilization vessel 1. As described above, the heat exchanger 11 is used for cooling the sterilization vessel. During cooling, the circulating pump 7 controls the opening and closing of the valve to connect the heat exchanger 11, send the process water into the heat exchanger 11 for cooling, and then return it to the sterilization vessel. Specifically, the heat exchanger 11 adopts a dual-pass structure with four ports. Two ports in one pass are used for refrigerant flow, and in the other pass, one port is connected to the circulating pump 7 via the cooling circulation valve 12, and the other port is connected to the sterilization tank 1 via the return water pipe 13. Specifically, the heat exchanger 11 adopts the structure of water-air heat exchanger, water-water heat exchanger, etc., so that the process water can achieve cooling and heat dissipation during the flow process. The drain valve 14 is used to discharge sediment in the sterilization vessel 1 or to discharge excess process water.

[0029] Specifically, such as Figure 4 As shown, the pipe opening connecting the steam preheating valve 2 and the sterilizer 1 is provided with a first steam pipe 201, which is located on the lower side of the product tray; the pipe opening connecting the steam valve 5 and the sterilizer 1 is provided with a second steam pipe 501, which is located between the product tray and the first steam pipe 201. As described above, when this sterilizer is in use, the first steam pipe 201 is located at the lowest point, and the process water will submerge the first steam pipe 201, which facilitates the heating of the process water by steam. The second steam pipe 501 is located above the first steam pipe 201 and does not contact the lower layer of process water. The product tray is located on the second steam pipe 501, so that the second steam pipe 501 can discharge steam upwards. When the circulating pump 7 circulates and sprays the heated process water, the steam can not only play a sterilization role, but also heat the sprayed process water, thereby maintaining the heating and sterilization temperature. Specifically, the second steam pipeline 501 can be provided with outlets on both sides to discharge steam to both sides.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A direct-heating and indirect-cooling sterilization process for a sterilizing autoclave, characterized in that, Includes the following steps: S1. Open the exhaust valve (9) and the water injection valve (3) to inject process water into the sterilization vessel (1) using the water injection pump (4); S2. Keep the exhaust valve (9) open and close the water pump (4) and the water valve (3). S3. Open the steam preheating valve (2), open the steam silencing mechanism (6), close the exhaust valve (9), and inject steam into the process water through the steam preheating valve (2) to preheat the process water so that the temperature of the process water is close to that of the product to be sterilized. S4. Close the steam preheating valve (2) and the steam silencing mechanism (6), and turn on the circulating pump (7), hot water circulating valve (8), steam valve (5), air replenishment valve (10) and exhaust valve (9). The process water enters the circulating pump (7) through the hot water circulating valve (8) for circulating spraying. Steam is supplied to the sterilizer (1) through the steam valve (5) to heat the process water. At the same time, air is replenished through the air replenishment valve (10) and exhausted through the exhaust valve (9), thereby adjusting the pressure inside the sterilizer (1). S5. After the process water is heated to the preset temperature, it is kept at that temperature until sterilization is complete. S6. Perform a slight cooling on the sterilization vessel (1) so that the internal temperature of the sterilization vessel (1) reaches the set temperature for slight cooling. S7. Cool the sterilizer (1) so that the internal temperature of the sterilizer (1) reaches the set cooling temperature.

2. The direct heating and indirect cooling sterilization process of the sterilizing autoclave as described in claim 1, characterized in that: The sterilization vessel (1) is equipped with a water injection level. The water injection level is lower than the product to be sterilized and does not exceed the pipeline connected to the steam preheating valve (2). The process water is injected to the water injection level and then stops.

3. The direct heating and intermittent cooling sterilization process of the sterilizing autoclave as described in claim 1, characterized in that: In steps S4, S5, S6 and S7, gas is supplied into the sterilizer (1) through the gas replenishment valve (10) to pressurize it, and the pressure is adjusted by the exhaust valve (9). PID control is implemented on the gas replenishment valve (10), the exhaust valve (9) and the steam valve (5), and the valve opening of the gas replenishment valve (10), the exhaust valve (9) and the steam valve (5) are adjusted in real time with reference to the linear temperature value of the sterilizer (1) so that the temperature change curve of the sterilizer (1) is a smooth curve.

4. The direct heating and intermittent cooling sterilization process of the sterilizing autoclave as described in claim 1, characterized in that, Step S6 includes: S61. A heat exchanger (11) is provided on the sterilization vessel (1), and a cooling circulation valve (12) and a return water pipe (13) are provided on the heat exchanger (11). S62. Close the hot water circulation valve (8), and use the circulation pump (7) to send the process water through the cooling circulation valve (12) into the heat exchanger (11) for heat dissipation and slight cooling. Then, send the slightly cooled process water back to the sterilization tank (1) through the return water pipe (13).

5. The direct heating and intermittent cooling sterilization process of the sterilizing autoclave as described in claim 1, characterized in that, It also includes step S8, which includes: S81. Turn off the circulation pump (7). S82. Keep the gas supply valve (10) and the exhaust valve (9) open, supply gas into the sterilizer (1) through the gas supply valve (10) to pressurize it, and regulate the exhaust pressure through the exhaust valve (9) to control the drainage pressure. S83. Open the drain valve (14) to drain the excess process water in the sterilization tank (1), and close the drain valve (14) after the process water level is lower than the initial liquid level.

6. The direct heating and intermittent cooling sterilization process of the sterilizing autoclave as described in claim 5, characterized in that, It also includes step S9, which includes: S91. Keep the exhaust valve (9) open and close the air supply valve (10). S92. Excess pressure is discharged through the exhaust valve (9) to reduce the internal pressure of the sterilizer (1) to the opening pressure. S93. Open the drain valve (14) to drain excess cooling water so that the process water level is lower than the initial level.

7. The direct heating and intermittent cooling sterilization process of the sterilizing autoclave as described in any one of claims 1 to 6, characterized in that: Step S4 is performed at least five times and step S7 is performed at least three times to segmentally regulate the internal temperature and pressure of the sterilizer (1).

8. A sterilizing autoclave, employing the direct heating and indirect cooling sterilization process as described in any one of claims 1 to 7, characterized in that, include: The sterilization vessel (1), steam preheating valve (2), water injection valve (3), water injection pump (4), steam valve (5), steam silencing mechanism (6), circulation pump (7), hot water circulation valve (8), exhaust valve (9), and air replenishment valve (10) are as follows: The sterilization vessel (1) is a horizontal sterilization vessel; The steam preheating valve (2), the water injection valve (3), the steam valve (5), the hot water circulation valve (8), the exhaust valve (9), and the air replenishment valve (10) are all connected to the sterilization kettle (1); The outlet of the water injection pump (4) is connected to the water injection valve (3); The steam silencing mechanism (6) is connected to the steam preheating valve (2); The inlet of the circulating pump (7) is connected to the sterilization vessel (1), and the outlet of the circulating pump (7) is connected to the hot water circulating valve (8).

9. The sterilization autoclave as described in claim 8, characterized in that: It also includes a heat exchanger (11), a cooling circulation valve (12), a return water pipe (13), and a drain valve (14), wherein, The heat exchanger (11) is located on the outside of the sterilization vessel (1); One end of the cooling circulation valve (12) is connected to the outlet of the circulation pump (7), and the other end is connected to one inlet of the heat exchanger (11). One end of the return water pipe (13) is connected to one outlet of the heat exchanger (11), and the other end is connected to the sterilization vessel (1); The drain valve (14) is connected to the sterilization vessel (1).

10. The sterilization autoclave as described in claim 8, characterized in that: The steam preheating valve (2) is connected to the sterilization vessel (1) by a first steam pipeline (201), which is located on the lower side of the product tray. The steam valve (5) is connected to the sterilizer (1) via a second steam pipe (501), which is located between the product tray (100) and the first steam pipe (201).

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