A control method for a hydrogen peroxide concentration system

Abstract

The present invention provides a control method for a hydrogen peroxide concentration system, including controlling the compressor's reflux valve to be in a fully open state and controlling the compressor's inlet pressure control valve to be in a closed state before the compressor is started; controlling the vacuum pump to start, and obtaining the operating pressure of the distillation device, the hydrogen peroxide temperature in the first channel, and the evaporation pressure of the first heat exchange medium in the second heat exchanger; determining the start time of the compressor according to the operating pressure, the hydrogen peroxide temperature, and the evaporation pressure of the first heat exchange medium; obtaining the suction and exhaust pressures of the compressor after the compressor is started; and controlling the working state of the compressor's reflux valve according to the suction and exhaust pressures. The control method of the present invention can effectively ensure the concentration efficiency of hydrogen peroxide and the product output and quality of concentrated hydrogen peroxide when the hydrogen peroxide concentration system is started smoothly.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen peroxide production, and in particular relates to a control method for a hydrogen peroxide concentration system. Background Art

[0002] Propylene oxide (PO) is a downstream derivative of propylene with a production capacity second only to that of polypropylene. It is widely used in the production of many high value-added chemicals such as propylene glycol, propylene carbonate, polyurethane, and unsaturated resins, and plays an irreplaceable role in the fields of transportation electronics, construction furniture, daily chemicals, and medicine. In recent years, with the continuous improvement of human production and living standards, the consumption of PO has shown an increasing trend year by year. The preparation methods of PO include the co-oxidation route with organic peroxide as the oxidant and the hydrogen peroxide method for preparing propylene oxide (HPPO). The HPPO process has the advantages of high atomic utilization, clean and efficient, and simple process, and occupies an important position in the production of propylene oxide.

[0003] Propylene oxide can be efficiently obtained by synthesizing propylene oxide from hydrogen peroxide and propylene in one step (HPPO method). At present, the demand for high-concentration hydrogen peroxide by the HPPO method continues to increase. In the existing hydrogen peroxide device, hydrogen peroxide concentration mainly uses fresh steam as the heat source of the distillation tower and the falling film evaporator, which consumes huge energy, has low thermal efficiency and high production cost; in addition, the temperature of hydrogen peroxide in the first channel of the falling film evaporator and the pressure at the top of the distillation tower are key parameters and affect each other. If the temperature of hydrogen peroxide in the first channel of the falling film evaporator increases, the pressure in the first channel of the falling film evaporator will also increase, and the pressure at the top of the distillation tower will also increase. When the temperature exceeds the value, the decomposition rate of hydrogen peroxide increases rapidly, and the falling film evaporator may have an overpressure explosion accident; if the temperature of hydrogen peroxide in the first channel of the falling film evaporator decreases, the pressure in the first channel of the falling film evaporator will also decrease, and the pressure at the top of the distillation tower will also decrease, and the evaporation amount of hydrogen peroxide in the first channel of the falling film evaporator will decrease, and the product output and quality of concentrated hydrogen peroxide will decrease. In addition, the hydrogen peroxide concentration system is usually unstable during startup and the startup efficiency cannot be guaranteed, which affects the quality of the concentrated hydrogen peroxide product. Developing a system control method that is efficient, stable and ensures the quality of concentrated hydrogen peroxide products has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of this, the present invention aims to provide a control method for a hydrogen peroxide concentration system, which can effectively ensure the concentration efficiency of hydrogen peroxide and the product output and quality of concentrated hydrogen peroxide when the hydrogen peroxide concentration system is started smoothly.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A control method for a hydrogen peroxide concentration system comprises a distillation device, a first heat exchanger and a heat supply heat pump device, wherein the first heat exchanger is used for hydrogen peroxide concentration;

[0007] The first heat exchanger comprises a first channel and a second channel, and hydrogen peroxide flows in the first channel;

[0008] The heat supply heat pump device comprises a first heat exchange circuit and a second heat exchange circuit, wherein a compressor, a third heat exchanger, a heat extracting medium storage component and a second heat exchanger are sequentially arranged on the first heat exchange circuit, and the third heat exchanger and the second channel are arranged on the second heat exchange circuit, wherein the first heat exchange medium in the first heat exchange circuit and the second heat exchange medium in the second heat exchange circuit can exchange heat in the third heat exchanger, so that the water in the hydrogen peroxide in the first channel is converted into steam, thereby realizing the concentration of the hydrogen peroxide, and the non-condensable gas in the steam discharged from the rectification device and the non-condensable gas in the second channel are discharged through a vacuum pump;

[0009] The control method comprises:

[0010] Before the compressor is started, the return valve of the compressor is controlled to be in a fully open state, and the inlet pressure control valve of the compressor is controlled to be in a closed state;

[0011] Controlling the vacuum pump to start, and obtaining the operating pressure of the rectification device, the temperature of the hydrogen peroxide in the first channel, and the evaporation pressure of the first heat exchange medium in the second heat exchanger;

[0012] Determining a start time of the compressor according to the operating pressure, the temperature of the hydrogen peroxide solution and the evaporation pressure of the first heat exchange medium;

[0013] After the compressor is turned on, obtaining the suction pressure and exhaust pressure of the compressor;

[0014] The working state of the return valve of the compressor is controlled according to the suction pressure and the exhaust pressure.

[0015] Further, the step of “determining the start time of the compressor according to the operating pressure, the temperature of the hydrogen peroxide solution and the evaporation pressure of the first heat exchange medium” includes:

[0016] The pressure control valve of the distillation device is adjusted so that the operating pressure reaches b1, the temperature of the hydrogen peroxide reaches c1, and the evaporation pressure of the first heat exchange medium is at d0, and then the compressor is controlled to start.

[0017] Further, the step of “controlling the working state of the return valve of the compressor according to the suction pressure and the exhaust pressure” includes:

[0018] When the suction pressure drops to d1, the opening of the return valve is reduced;

[0019] When the exhaust pressure rises to e1 and the suction pressure continues to decrease to d2, the opening of the return valve is controlled to be adjusted to f1, wherein d2 <d1。

[0020] Furthermore, after the step of adjusting the opening of the return valve to f1, the control method further comprises:

[0021] Reduce the opening of the return valve to f2, so that the exhaust pressure increases to e2 and the intake pressure decreases to d3, wherein d3<d2,e2> e1.

[0022] Furthermore, the control method further includes:

[0023] When the compressor is running, the operating pressure of the rectification device and the temperature of the hydrogen peroxide in the first channel are obtained again; the timing of obtaining is after the above steps;

[0024] The working state of the inlet pressure control valve of the compressor is controlled according to the reacquired operating pressure of the rectification device and the temperature of the hydrogen peroxide in the first channel.

[0025] Further, the step of “controlling the working state of the inlet pressure control valve of the compressor according to the re-acquired operating pressure of the distillation device and the temperature of the hydrogen peroxide in the first channel” includes:

[0026] The opening of the pressure control valve of the distillation device is reduced. If the operating pressure of the distillation device obtained again is maintained at b1 and the temperature of the hydrogen peroxide obtained again is increased to c2, the opening of the inlet pressure control valve of the compressor is controlled to increase from fully closed to h1.

[0027] Further, after the step of increasing the opening of the compressor inlet pressure control valve from fully closed to h1, the control method further includes:

[0028] Continue to reduce the opening of the return valve to fully closed, and obtain the exhaust pressure, suction pressure of the compressor and the temperature of the hydrogen peroxide in the first channel again;

[0029] The opening of the pressure control valve of the rectification device and the opening of the compressor inlet pressure control valve are controlled according to the re-acquired compressor exhaust pressure, suction pressure and the temperature of the hydrogen peroxide in the first channel.

[0030] Further, the step of “controlling the opening of the pressure control valve of the rectification device and the opening of the compressor inlet pressure control valve according to the re-acquired compressor exhaust pressure, suction pressure and the temperature of the hydrogen peroxide in the first channel” includes:

[0031] If the exhaust pressure of the compressor obtained again increases to e3, the suction pressure decreases to d4, and the temperature of the hydrogen peroxide in the first channel increases to c3, the opening of the pressure control valve of the distillation device is controlled to be reduced to value a3, and the inlet pressure control valve of the compressor is controlled to increase to h2.

[0032] Further, it is characterized in that: the second heat exchange circuit is also provided with a steam condensate tank located between the outlet end of the second channel and the inlet end of the third heat exchanger, the concentration system also includes a regulating branch, the regulating branch is connected to the second heat exchange circuit, one end of the regulating branch is connected to between the third heat exchanger and the second channel, and the other end is connected to the steam condensate tank, the regulating branch is provided with an air cooler, and the control method further includes:

[0033] When starting the compressor, starting the air cooler;

[0034] The working state of the air cooler is selectively controlled according to the exhaust pressure of the compressor and the evaporation pressure of the first heat exchange medium in the second heat exchanger.

[0035] Further, the step of “selectively controlling the working state of the air cooler according to the exhaust pressure of the compressor and the evaporation pressure of the first heat exchange medium in the second heat exchanger” includes:

[0036] If the exhaust pressure of the compressor is lower than e1, the fan frequency of the air cooler is reduced;

[0037] If the exhaust pressure of the compressor is higher than e1, the fan frequency of the air cooler is increased;

[0038] After the reflux valve is closed, when the compressor outlet pressure increases to the normal operating value e3, the compressor inlet pressure decreases to the normal operating value d4, and the hydrogen peroxide temperature in the first channel of the falling film evaporator increases to the normal operating value c3, the air cooler is controlled to be closed.

[0039] Compared with the prior art, the control method of the hydrogen peroxide concentration system of the present invention has the following advantages:

[0040] The control method of the hydrogen peroxide concentration system of the present invention can be adjusted according to the hydrogen peroxide temperature in the first channel of the falling film evaporator and the pressure at the top of the distillation tower, thereby avoiding overpressure explosion accidents. When the hydrogen peroxide concentration system is started smoothly, the concentration efficiency of hydrogen peroxide and the product output and quality of concentrated hydrogen peroxide are effectively guaranteed. By recycling and compressing the heat-extracting working medium, the steam condensate is gasified again to provide a heat source for hydrogen peroxide concentration. The purpose of the present invention is to use electric energy instead of fresh steam, greatly reduce energy consumption, and save production costs in the hydrogen peroxide concentration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 This is a schematic diagram of the hydrogen peroxide concentration system described in Example 1 of the present invention.

[0043] Description of reference numerals:

[0044] 1. Distillation tower; 2. Falling film evaporator; 3. Hydrogen peroxide circulation pump; 4. Steam condensate tank; 5. Condenser; 6. Steam condensate feed pump; 7. Heat extraction medium storage tank; 8. Evaporator; 9. Vacuum pump; 10. Compressor; 11. Gas-liquid separation component; 12. Air cooler; 13. Liquid level control valve; 14. Temperature control valve; 15. Pressure control valve; 16. Reflux valve. DETAILED DESCRIPTION

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "back", "top", "bottom", "inside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1 As shown, a hydrogen peroxide concentration system includes a distillation tower 1, a falling film evaporator 2, a heat supply heat pump device, a condenser 5, a vacuum pump 9, and an air cooler 12.

[0050] The falling film evaporator 2 is used for concentrating hydrogen peroxide, and comprises a first channel and a second channel. Hydrogen peroxide flows in the first channel, and a heat exchange medium capable of exchanging heat with hydrogen peroxide flows in the second channel.

[0051] The heat supply heat pump device includes a first heat exchange circuit, in which a first heat exchange medium flows, and the first heat exchange circuit is provided with a heat-extracting medium storage tank 7, a compressor 10 and an evaporator 8, the heat-extracting medium storage tank 7 can store the first heat exchange medium, the evaporator 8 is arranged between the heat-extracting medium storage tank 7 and the compressor 10, and the distillation tower 1 is connected to the evaporator 8. The pressure drop of water vapor in the evaporator 8 needs to be less than 3kPa, and the heat exchanger type of the evaporator 8 can be BXM, BKU, BKM, falling film evaporator, etc.

[0052] The first heat exchange circuit is also provided with a condenser 5, which is provided between the exhaust port of the compressor 10 and the heat extracting medium storage tank 7; the heat supply heat pump device also includes a second heat exchange circuit, in which a second heat exchange medium flows, and the second heat exchange circuit is provided with a condenser 5 and a steam condensate tank 4; the second channel is connected to the second heat exchange circuit, one end of the second channel is connected to the condenser 5, and the other end of the second channel is connected to the steam condensate tank 4; the condenser 5 is configured to enable the first heat exchange medium and the second heat exchange medium to exchange heat to provide heat for the falling film evaporator 2. The evaporator 8 is connected to the steam condensate tank 4, and the liquid after the steam discharged from the distillation tower 1 is heat-exchanged by the evaporator 8 enters the steam condensate tank 4. The first heat exchange medium can provide heat for the falling film evaporator 2, so that the water in the hydrogen peroxide in the first channel is converted into steam and passed into the distillation tower 1, so as to achieve the concentration of the hydrogen peroxide. Specifically, the heat of the first heat exchange medium is transferred to the second heat exchange circuit through the condenser 5, and the second heat exchange circuit transfers the heat to the second channel of the falling film evaporator 2, so that the water in the first channel is evaporated, so as to achieve the concentration of the hydrogen peroxide; the evaporator 8 is configured to enable the steam discharged from the distillation tower 1 to exchange heat with the first heat exchange medium, so that the first heat exchange medium is evaporated back into the compressor 10, and the pressure drop of the water vapor in the condenser 5 needs to be less than 5kPa. The heat exchanger type of the condenser 5 can be BXM, BKU, BKM, or a falling film evaporator.

[0053] The non-condensable gas of the distillation tower 1 after heat exchange in the evaporator 8 and the non-condensable gas of the falling film evaporator 2 are extracted through the vacuum pump 9; the two sides of the vacuum pump 9 are also connected to the two ends of the pressure regulating branch, and the pressure regulating branch is configured to control the pressure and temperature of the top part of the distillation device tower by controlling the vacuum pump 9; and / or the pressure range of the top part of the distillation tower 1 is 6~10kPaA, and the temperature is 36~46℃.

[0054] The first channel is also provided with a liquid level control branch connected thereto, and a liquid level control valve 13 is provided on the liquid level control branch. The liquid level control valve 13 is configured to control the amount of hydrogen peroxide in the first channel by adjusting the feed amount of rare hydrogen peroxide; the first channel is also provided with a temperature control branch connected thereto, and a temperature control valve 14 is provided on the temperature control branch. The temperature control valve 14 is configured to control the temperature of hydrogen peroxide in the first channel by adjusting the discharge amount of concentrated hydrogen peroxide.

[0055] The temperature of the hydrogen peroxide in the first channel is 55-65°C, and the pressure is 8-12 kPaA; the temperature of the steam generated in the second channel is 65-75°C, and the pressure is 25-35 kPaA.

[0056] The condensation temperature of the first heat exchange medium is 75-85°C, and the evaporation temperature is 25-35°C; preferably, the first heat exchange medium can be one or more of n-butane, isobutane, R134a, R245fa, ammonia, and propylene. In this specific embodiment, the second heat exchange medium is water. Of course, the specific type of the second heat exchange medium is not restrictive, and those skilled in the art can set it according to actual conditions.

[0057] A flow meter is provided at the outlet of the compressor 10 to detect the condensation amount of the heat-taking medium in the condenser 5. The compressor 10 is driven by a motor; a pressure control valve 15 is provided at the inlet of the compressor 1010, and the compressor 10 is provided with a return valve 16. The temperature, pressure and flow of the heat-taking medium at the outlet of the compressor 10 are adjusted by adjusting the pressure control valve 15 and the return valve 16 at the inlet of the compressor 10.

[0058] The compressor 10 is also connected to a gas-liquid separation member 11 .

[0059] The concentration system also includes a regulating branch, which is connected to the second heat exchange circuit. One end of the regulating branch is connected between the condenser 5 and the second channel, and the other end is connected to the steam condensate tank 4. An air cooler 12 is provided on the regulating branch.

[0060] Workflow:

[0061] The heat extracting medium evaporates in the evaporator 8, enters the gas-liquid separation component 11 for separation, and then enters the compressor 10 for compression. The compressed heat extracting medium enters the condenser 5 for condensation, and then enters the heat extracting medium storage tank 7, and then enters the evaporator 8 for evaporation. The steam condensate is sent to the condenser 5 by the steam condensate feed pump 6 for gasification, and then enters the second channel of the falling film evaporator 2 to provide a heat source (the steam will enter the air cooler 12 for condensation during the start-up phase), and enters the steam condensate tank 4 after condensation. The falling film evaporator 2 is provided with a hydrogen peroxide circulation pump 3, and a rare hydrogen peroxide feed and a concentrated hydrogen peroxide discharge are arranged on the circulation pipeline. The first channel of the falling film evaporator 2 generates steam and enters the distillation tower 1. There is pure water feed at the top of the distillation tower 1, concentrated hydrogen peroxide is produced at the bottom of the tower, and water vapor produced at the top of the tower enters the evaporator 8, and enters the steam condensate tank 4 after condensation. The non-condensable gas in the distillation tower 1 after condensation in the evaporator 8 and the non-condensable gas in the second channel of the falling film evaporator 2 are discharged through the vacuum pump 9 .

[0062] The control method of the system includes:

[0063] Before the compressor 10 is started, the return valve 16 of the compressor 10 is controlled to be in a fully open state, and the inlet pressure control valve 15 of the compressor 10 is controlled to be in a closed state. Further, the start timing of the compressor 10 is determined according to the operating pressure, the temperature of the hydrogen peroxide solution and the evaporation pressure of the first heat exchange medium; the pressure control valve of the distillation tower 1 is adjusted so that the operating pressure reaches b1, the temperature of the hydrogen peroxide solution reaches c1, and the evaporation pressure of the first heat exchange medium is at d0, and then the compressor 10 is controlled to start.

[0064] When the compressor 10 is started, the air cooler 12 is started; and according to the exhaust pressure of the compressor 10 and the evaporation pressure of the first heat exchange medium in the evaporator 8, the working state of the air cooler 12 is selectively controlled.

[0065] Specifically, if the exhaust pressure of the compressor 10 is lower than e1, the fan frequency of the air cooler 12 is reduced; if the exhaust pressure of the compressor 10 is higher than e1, the fan frequency of the air cooler 12 is increased; after the return valve 16 is closed, when the outlet pressure of the compressor 10 increases to the normal operating value e3, the inlet pressure of the compressor 10 decreases to the normal operating value d4, and the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases to the normal operating value c3, the air cooler 12 is controlled to be closed.

[0066] Furthermore, the vacuum pump 9 is controlled to start, and the operating pressure of the distillation tower 1 , the temperature of the hydrogen peroxide in the first channel, and the evaporation pressure of the first heat exchange medium in the evaporator 8 are obtained.

[0067] After the compressor 10 is turned on, the suction pressure and the exhaust pressure of the compressor 10 are obtained. According to the suction pressure and the exhaust pressure, the working state of the return valve 16 of the compressor 10 is controlled.

[0068] When the suction pressure drops to d1, the opening of the return valve 16 is reduced;

[0069] When the exhaust pressure rises to e1 and the intake pressure continues to decrease to d2, the opening of the return valve 16 is controlled to be adjusted to f1, wherein d2 <d1。

[0070] After the step of adjusting the opening of the return valve 16 to f1, the method further includes: reducing the opening of the return valve 16 to f2, so that the exhaust pressure is increased to e2 and the intake pressure is reduced to d3, wherein d3<d2,e2> e1.

[0071] Furthermore, when the compressor 10 is running, the operating pressure of the distillation tower 1 and the temperature of the hydrogen peroxide in the first channel are obtained again; and the working state of the inlet pressure control valve 15 of the compressor 10 is controlled according to the operating pressure of the distillation tower 1 and the temperature of the hydrogen peroxide in the first channel obtained again.

[0072] The opening of the pressure control valve of the distillation device is reduced. If the operating pressure of the distillation tower 1 obtained again is maintained at b1 and the temperature of the hydrogen peroxide obtained again is increased to c2, the opening of the inlet pressure control valve 15 of the compressor 10 is controlled to increase from fully closed to h1.

[0073] After the step of increasing the opening of the inlet pressure control valve 15 of the compressor 10 from fully closed to h1, the method further includes: continuing to reduce the opening of the reflux valve 16 to fully closed, and obtaining the exhaust pressure, suction pressure and temperature of the hydrogen peroxide in the first channel of the compressor 10 again; and controlling the opening of the pressure control valve of the distillation tower 1 and the opening of the inlet pressure control valve 15 of the compressor 10 according to the exhaust pressure, suction pressure and temperature of the hydrogen peroxide in the first channel obtained again.

[0074] If the exhaust pressure of the compressor 10 obtained again increases to e3, the suction pressure decreases to d4, and the temperature of the hydrogen peroxide in the first channel increases to c3, the opening of the pressure control valve of the distillation tower 1 is controlled to decrease to a3, and the inlet pressure control valve 15 of the compressor 10 is controlled to increase to h2, and the hydrogen peroxide concentration system starts efficiently and smoothly.

[0075] Specifically, the control method of the present invention operates as follows:

[0076] During the start-up phase, the compressor 10 will be started first, the distillation tower 1 and the falling film evaporator 2 will be in a no-flow state, and the air cooler 12 will be started; after the steam condenses and vaporizes in the condenser 5, it enters the air cooler 12 for cooling; the control of the start-up process is as follows:

[0077] a. Before starting the compressor 10, the return valve 16 of the compressor 10 is in a fully open state, the inlet pressure control valve 15 of the compressor 10 is in a fully closed state, and the inlet and outlet pressures of the compressor 10 are equal;

[0078] b. Start the vacuum pump 9, the opening of the pressure control valve of the distillation tower 1 is at value a1, the pressure of the distillation tower 1 is at the normal operating value b1, the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 is at value c1, and the pressure of the heat medium in the evaporator 8 is at the normal operating value d0;

[0079] c. Start the compressor 10, the compressor 10 inlet pressure will decrease, and the compressor 10 outlet pressure will increase; when the compressor 10 inlet pressure decreases to the value d1, the opening of the return valve 16 begins to decrease, the compressor 10 inlet pressure continues to decrease, and the compressor 10 outlet pressure continues to increase;

[0080] d. When the outlet pressure of the compressor 10 increases to the value e1, the gas phase of the heat extracting medium begins to condense in the condenser 5. At this time, the inlet pressure of the compressor 10 decreases to the value d2. At this time, the opening degree of the return valve 16 is at the value f1;

[0081] e. Start the air cooler 12 while starting the compressor 10. The air cooler 12 uses a variable frequency fan. When the outlet pressure of the compressor 10 is lower than the value e1, the vaporization amount of the steam condensate in the condenser 5 is small. At this time, the frequency value of the variable frequency fan of the air cooler 12 is g1. When the outlet pressure of the compressor 10 rises to the value e1, the vaporization amount of the steam condensate in the condenser 5 is large. The frequency value of the variable frequency fan is g2.

[0082] f. Then the opening of the reflux valve 16 continues to decrease. When the outlet pressure of the compressor 10 increases to the value e2, the inlet pressure of the compressor 10 decreases to the value d3, the opening of the reflux valve 16 is at the value f2, the condensation temperature and condensation amount of the heat medium in the condenser 5 increase, the vaporization amount of the steam condensate in the condenser 5 increases, and the steam condensate in the condenser 55 will enter the air cooler 12 and the second channel of the falling film evaporator 2 for condensation after vaporization. At this time, the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases to the value c2, and steam is generated to enter the distillation tower 1. The opening of the pressure control valve of the distillation tower 1 decreases to the value a2, and the pressure of the distillation tower 1 is maintained at the normal operating value b1. The steam from the top of the distillation tower 1 enters the evaporator 8, and the opening of the inlet pressure control valve 15 of the compressor 10 increases from fully closed to the value h1, and the pressure of the heat medium in the evaporator 88 is maintained at the normal operating value d0;

[0083] g. Then the opening of the reflux valve 16 continues to decrease to fully closed. At this time, when the outlet pressure of the compressor 10 increases to the normal operating value e3, the inlet pressure of the compressor 10 decreases to the normal operating value d4, the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases to the normal operating value c3, the opening of the distillation tower 1 pressure control valve 15 decreases to value a3, the pressure of the distillation tower 1 maintains the normal operating value b1, the inlet pressure of the compressor 10 control valve 15 increases to value h2, the heat extraction medium pressure in the evaporator 8 maintains the normal operating value d0, and the variable frequency fan of the air cooler 12 is turned off.

[0084] Specifically, a3<a2<a1, c1<c2<c3, d4<d3<d0<d2<d1, e1<e2<e3, f2<f1, g1<g2, h1<h2. Among them, a1, a2, etc. do not represent a numerical value, but can be a range, as long as it does not exceed the basic principle defined by the present invention, it falls within the protection scope.

[0085] During the operation of the hydrogen peroxide concentration system, the hydrogen peroxide temperature in the first channel of the falling film evaporator 2 and the pressure at the top of the distillation tower 1 are key parameters and affect each other. If the hydrogen peroxide temperature in the first channel of the falling film evaporator 2 increases, the pressure in the first channel of the falling film evaporator 2 will also increase, and the pressure at the top of the distillation tower 1 will also increase. When the temperature exceeds the value, the decomposition rate of hydrogen peroxide increases rapidly, and an overpressure explosion accident may occur in the falling film evaporator 2; if the hydrogen peroxide temperature in the first channel of the falling film evaporator 2 decreases, the pressure in the first channel of the falling film evaporator 2 will also decrease, and the pressure at the top of the distillation tower 1 will also decrease, and the evaporation amount of hydrogen peroxide in the first channel of the falling film evaporator 2 will decrease, and the product output and quality of concentrated hydrogen peroxide will decrease. If the hydrogen peroxide temperature in the first channel of the falling film evaporator 2 and the pressure at the top of the distillation tower 1 deviate from the normal operating values, the following adjustments will be made:

[0086] When the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases, the pressure at the top of the distillation tower 1 will also increase. The control method is as follows:

[0087] 1. If the temperature of hydrogen peroxide in the first channel of falling film evaporator 2 increases, the pressure at the top of distillation tower 1 will also increase. At this time, the system will automatically control as follows:

[0088] 1.1) The opening of the temperature control valve 14 of the falling film evaporator 2 increases, the discharge flow of concentrated hydrogen peroxide increases, the liquid level of the first channel of the falling film evaporator 2 decreases, the opening of the liquid level control valve 13 of the falling film evaporator 2 increases, and the feed flow of rare hydrogen peroxide increases. The concentrated hydrogen peroxide with a higher temperature is produced, and the rare hydrogen peroxide with a lower temperature enters, thereby reducing the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2;

[0089] 1.2) The opening of the pressure control valve of the distillation tower 1 becomes smaller, and the vacuum pump 9 provides a higher vacuum pumping capacity, thereby reducing the pressure of the distillation tower 1, thereby reducing the pressure of the first channel of the falling film evaporator 2, and thereby reducing the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2;

[0090] 1.3) When the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases, the temperature and flow rate of the steam at the top of the distillation tower 1 will increase, so that the evaporation amount and evaporation pressure of the heat extracting medium in the evaporator 8 will increase, so that the inlet pressure of the compressor 10 will increase, so that the opening of the inlet pressure control valve 15 of the compressor 10 will decrease, so that the inlet pressure and flow rate of the compressor 10 will decrease, so that the outlet pressure and flow rate of the compressor 10 will decrease, so that the vaporization temperature, pressure and vaporization amount of the steam condensate in the condenser 5 will decrease, so that the temperature and flow rate of the steam entering the second channel of the falling film evaporator 2 will decrease, so that the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 will decrease;

[0091] 1.4) In step 1.3, if the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 is too high, resulting in a small opening of the compressor 10 inlet pressure control valve 15, too small compressor 10 inlet pressure and flow, and compressor 10 surges, then the return valve 16 will be opened from a fully closed state to a certain opening, so that the compressor 10 inlet pressure and flow recover to ensure stable operation of the compressor 10;

[0092] 1.5) If the motor of the compressor 10 adopts a variable frequency motor, when the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 increases, the motor frequency decreases, the speed decreases, and the outlet pressure and flow rate of the compressor 10 decrease, so that the condensate vaporization temperature, pressure and vaporization amount in the condenser 5 decrease, so that the steam temperature and flow rate entering the second channel of the falling film evaporator 2 decrease, and the temperature of the hydrogen peroxide in the first channel of the falling film evaporator 2 decreases;

[0093] 2. When the temperature of hydrogen peroxide in the first channel of falling film evaporator 2 decreases, the pressure at the top of distillation tower 1 will also decrease. At this time, the adjustment method of the system is opposite to the above steps.

[0094] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for a hydrogen peroxide concentration system, characterized in that: It includes a distillation device, a falling film evaporator and a heat supply heat pump device, wherein the falling film evaporator is used for concentrating hydrogen peroxide; The falling film evaporator comprises a first channel and a second channel, wherein hydrogen peroxide flows in the first channel; The heat supply heat pump device comprises a first heat exchange circuit and a second heat exchange circuit, wherein the first heat exchange circuit is provided with a compressor, a condenser, a heat extracting medium storage component and an evaporator in sequence, and the second heat exchange circuit is provided with the condenser and the second channel, and the first heat exchange medium in the first heat exchange circuit and the second heat exchange medium in the second heat exchange circuit can exchange heat in the condenser, so that the water in the hydrogen peroxide in the first channel is converted into steam, so as to realize the concentration of the hydrogen peroxide, and the non-condensable gas in the steam discharged from the distillation device and the non-condensable gas in the second channel are discharged through a vacuum pump; The control method comprises: Before the compressor is started, the return valve of the compressor is controlled to be in a fully open state, and the inlet pressure control valve of the compressor is controlled to be in a closed state; Controlling the vacuum pump to start, and obtaining the operating pressure of the rectification device, the temperature of the hydrogen peroxide in the first channel, and the evaporation pressure of the first heat exchange medium in the evaporator; Determining a start time of the compressor according to the operating pressure, the temperature of the hydrogen peroxide solution and the evaporation pressure of the first heat exchange medium; After the compressor is turned on, obtaining the suction pressure and the exhaust pressure of the compressor; According to the suction pressure and the exhaust pressure, the working state of the reflux valve of the compressor is controlled; when the compressor is running, the operating pressure of the distillation device and the temperature of the hydrogen peroxide in the first channel are obtained again; The working state of the inlet pressure control valve of the compressor is controlled according to the reacquired operating pressure of the distillation device and the temperature of the hydrogen peroxide in the first channel.

2. The control method of the hydrogen peroxide concentration system according to claim 1, characterized in that: The step of "determining the start time of the compressor according to the operating pressure, the temperature of the hydrogen peroxide solution and the evaporation pressure of the first heat exchange medium" includes: The pressure control valve of the distillation device is adjusted so that the operating pressure reaches b1, the temperature of the hydrogen peroxide reaches c1, and the evaporation pressure of the first heat exchange medium is at d0, and then the compressor is controlled to start.

3. The control method of the hydrogen peroxide concentration system according to claim 1, characterized in that: The step of "controlling the working state of the return valve of the compressor according to the suction pressure and the exhaust pressure" includes: When the suction pressure drops to d1, the opening of the return valve is reduced; When the exhaust pressure rises to e1 and the intake pressure continues to decrease to d2, the opening of the return valve is controlled to be adjusted to f1, wherein d2 <d1。 4. The control method of the hydrogen peroxide concentration system according to claim 3, characterized in that: After the step of adjusting the opening of the return valve to f1, the control method further comprises: Reduce the opening of the return valve to f2, so that the exhaust pressure increases to e2 and the intake pressure decreases to d3, wherein d3<d2,e2> e1.

5. The control method of the hydrogen peroxide concentration system according to claim 1, characterized in that: The step of "controlling the working state of the inlet pressure control valve of the compressor according to the re-acquired operating pressure of the distillation device and the temperature of the hydrogen peroxide in the first channel" includes: The opening of the pressure control valve of the distillation device is reduced. If the operating pressure of the distillation device obtained again is maintained at b1 and the temperature of the hydrogen peroxide obtained again is increased to c2, the opening of the inlet pressure control valve of the compressor is controlled to increase from fully closed to h1.

6. The control method of the hydrogen peroxide concentration system according to claim 5, characterized in that: After the step of increasing the opening of the compressor inlet pressure control valve from fully closed to h1, the control method further includes: Continue to reduce the opening of the return valve to fully closed, and obtain the exhaust pressure, suction pressure of the compressor and the temperature of the hydrogen peroxide in the first channel again; The opening of the pressure control valve of the rectification device and the opening of the compressor inlet pressure control valve are controlled according to the re-acquired compressor exhaust pressure, suction pressure and the temperature of the hydrogen peroxide in the first channel.

7. The control method of the hydrogen peroxide concentration system according to claim 6, characterized in that: The step of "controlling the opening of the pressure control valve of the rectification device and the opening of the compressor inlet pressure control valve according to the re-acquired compressor exhaust pressure, suction pressure and the temperature of the hydrogen peroxide in the first channel" includes: If the exhaust pressure of the compressor obtained again increases to e3, the suction pressure decreases to d4, and the temperature of the hydrogen peroxide in the first channel increases to c3, the opening of the pressure control valve of the distillation device is controlled to be reduced to value a3, and the inlet pressure control valve of the compressor is controlled to increase to h2.

8. The control method of the hydrogen peroxide concentration system according to any one of claims 1 to 7, characterized in that: The second heat exchange circuit is also provided with a steam condensate tank located between the outlet end of the second channel and the inlet end of the condenser, the concentration system also includes a regulating branch, the regulating branch is connected to the second heat exchange circuit, one end of the regulating branch is connected to between the condenser and the second channel, and the other end is connected to the steam condensate tank, the regulating branch is provided with an air cooler, and the control method further includes: When starting the compressor, starting the air cooler; The working state of the air cooler is selectively controlled according to the exhaust pressure of the compressor and the evaporation pressure of the first heat exchange medium in the evaporator.

9. The control method of the hydrogen peroxide concentration system according to claim 8, characterized in that: The step of "selectively controlling the working state of the air cooler according to the exhaust pressure of the compressor and the evaporation pressure of the first heat exchange medium in the evaporator" includes: If the exhaust pressure of the compressor is lower than e1, the fan frequency of the air cooler is reduced; If the exhaust pressure of the compressor is higher than e1, the fan frequency of the air cooler is increased; After the reflux valve is closed, when the compressor outlet pressure increases to the normal operating value e3, the compressor inlet pressure decreases to the normal operating value d4, and the hydrogen peroxide temperature in the first channel of the falling film evaporator increases to the normal operating value c3, the air cooler is controlled to be closed.

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